Abstract:
A control device capable of moving a vehicle in a direction with an angle larger than at least the maximum steering angle of wheels. When the wheels ( 2 ) are brought into a parallel movement arrangement as shown in FIG.  3 ( a ) and rotatingly driven according to the depressed amount of an accelerator pedal ( 53 ), the wheels ( 2 ) are slippingly moved on a road surface. Thus, while the vehicle forward component of a drive force generated by the right and left front wheels ( 2 FR) and ( 2 FL) and the vehicle rearward component of a drive force generated by the right and left rear wheels ( 2 RR) and ( 2 RL) balance each other out, the vehicle rightward component of a drive force generated by the right and left front wheels ( 2 FR) and ( 2 FL) and the vehicle rightward component of a drive force generated by the right and left rear wheels ( 2 RR) and ( 2 RL) act as a drive force for moving the vehicle ( 1 ) rightward. As a result, the vehicle ( 1 ) can be moved, in parallel, in the right side direction of the vehicle.

Description:
INCORPORATION BY REFERENCE 
       [0001]    The disclosure of Japanese Patent Application No. 2006-308561 filed on Apr. 24, 2006 including the specification, drawings and abstract is incorporated herein by reference in its entirety. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a controlling apparatus that controls a vehicle having a plurality of steerable wheels, an actuator unit that drives to steer each of the steerable wheels independently, and a wheel driving unit that drives to rotate each of the steerable wheels independently, to move the vehicle in a given direction by operating the actuator unit and the wheel driving unit to control steering and rotation of the steerable wheels, and also relates to a vehicle having the controlling apparatus. The present invention also relates to a controlling apparatus that controls a vehicle having steerable wheels and an actuator unit that steers the steerable wheels, to control steering of the steerable wheels by driving the actuator unit, and more particularly to drive the vehicle to make a turn appropriately depending on the environment surrounding the vehicle, and also relates to a vehicle having such a controlling apparatus. 
         [0004]    2. Description of the Related Art 
         [0005]    Parallel parking is generally achieved by a sequence of operations including a driver backing up a vehicle in parallel to the road, turning the steering wheel when the rear end of the vehicle becomes roughly parallel with the edge of the parking space, then as the rear end of the vehicle enters the parking space, turning the steering wheel in the reverse direction to position and park the vehicle in the targeted parking space. 
         [0006]    Parallel parking requires some driving skill, and is difficult for an inexperienced driver to judge when to start turning the steering wheel and how much to turn, or at what point to start turning the steering wheel in the reverse direction. 
         [0007]    Various technologies have been developed to aid parallel parking. For example, Japanese Patent Application Publication No. JP-A-2001-180407 discloses a driver-aid apparatus including a camera, a display monitor arranged in a position that is visually recognizable by the driver, and a display controlling unit. According to the disclosure, the camera captures an image of the rear end of the vehicle on which the apparatus is mounted, the captured image is displayed on the monitor, and guiding information is superimposed over the image on the monitor by the display controlling unit so to aid the driver. 
         [0008]    According to this technology, because the guiding information is displayed on the monitor, such as marks indicating how much the steering wheel is actually turned and how much it should be turned, and a mark indicating where to turn the steering wheel in the reverse direction, the driver can just follow the guiding information on the monitor, easily understanding when and how much to turn the steering wheel. 
         [0009]    However, it is a driver-aid technology and is not intended to improve a steering capability of the vehicle itself. Therefore, as shown in  FIG. 15A , when a road width, or a spacing in the front or back of the vehicle in the parking space is extremely limited, the vehicle could bump into a parked car or other obstacles upon entering the parking space, or get stuck in the parking space. Furthermore, the driver may be unable to fit the entire vehicle body into the parking space with a part of the vehicle sticking out, thus being an obstacle for other incoming vehicles. 
         [0010]    The inventors of the present inventions have made extensive investigations to solve these problems, and developed a technology using a mechanism that allows horizontal movement of wheels (that is, with a steered angle of 90 degrees), as shown in  FIG. 15B . According to this technology, a vehicle can be parallel-moved in the lateral (right and left) directions. Therefore, the driver can parallel park the vehicle easily, even when a road width or a spacing in the front or back of the vehicle in the parking space is extremely limited. 
         [0011]    Currently, upon making a turn with a generally available passenger vehicle, only a turn within a limited radius can be made, because the steering mechanism thereof determines the maximum steerable angle of two front wheels or four front and rear wheels. Therefore, if there is not enough space, the steering wheel will need to be turned back and forth many times to change the orientation of the vehicle, or sometimes it will become impossible to turn the vehicle. 
         [0012]    With reference to  FIGS. 25A ,  26 A,  27 A, and  28 A, various scenarios for moving a vehicle out of a parking lot are explained by way of example. A driver is attempting to move a vehicle  100  of a standard size (length 4,795 millimeters×width 1,790 millimeters×height 1,770 millimeters) out from a parking space  110  (width 2.3 meters×length 5.0 meters) into a driveway  120  (width 5.5 meters) that is perpendicular to the parking space  110 , by operating the steering wheel and the gas pedal. 
         [0013]      FIG. 25A  is a diagram for showing the vehicle  100  turning left in the forward direction around a turning axis A 1  with a minimum radius of 5.8 meters. In this example, the vehicle  100  scrapes against a wall  120   a  standing along the side of the driveway  120  across the parking space  110 . Therefore, the steering wheel must be turned back and forth multiple times to avoid scraping the wall  120   a.    
         [0014]      FIG. 26A  is a diagram for showing the vehicle  100  turning left in the forward direction around a turning axis B 1  with a minimum radius of 5.8 meters to avoid bumping into a vehicle  140  parked in front thereof. In this example, the vehicle  100  runs across a parking space adjacent to the parking space  110 , and will scrape against a vehicle  130  parked in the adjacent parking space. 
         [0015]      FIG. 27A  is a diagram for showing the vehicle  100  turning left in the forward direction around a turning axis C 1  with a minimum radius of 5.8 meters to avoid scraping against the vehicle  130  parked in the parking space adjacent to the parking space  110 . However, if a vehicle  140  is parked in front thereof, the vehicle  100  will scrape against the vehicle  140  as shown in  FIG. 27A . 
         [0016]      FIG. 28A  is a diagram for showing another example where a driver is attempting to turn the vehicle  100  to the left in the forward direction to avoid clipping the edge of the opening  170   a  on a curb  170  and enter a roadway  160  having one lane in each direction by operating the steering wheel and the gas pedal. 
         [0017]    In  FIG. 28A , the vehicle  100  is turned into the leftward lane of the roadway  160  with a turning axis D 1  with a minimum radius of 5.8 meters to avoid scraping the opening  170   a . If the lane width (the width of the one-way lane with a boundary at a center line  180 ) is limited, the vehicle  100  overruns the center line  180  at some moment upon turning. It is very dangerous for the vehicle  100  to overrun the center line  180  upon turning, because the vehicle  100  can collide with a vehicle  150  coming from the opposite direction. 
         [0018]    As explained above, depending on the surrounding environment, there are many situations where a driver experiences difficulty in making a turn with the conventional vehicle  100  with a limited radius. In order to overcome the difficulty, Japanese Patent Application Publication No. JP-A-2003-146234, for example, discloses a controlling apparatus for an electric vehicle having four wheels at the right front, the left front, the right rear, and the left rear steered and driven by independent steering motors and driving motors upon making a turn, in accordance with limiting conditions (road conditions that greatly influence steering and driving of a vehicle) that are unique to facilities along roadways. 
         [0019]    In the controlling apparatus disclosed in the Japanese Patent Application Publication No. JP-A-2003-146234, a driver selects a steering mode from a plurality of steering modes having different overall patterns including various swept paths of each wheel, and sets a driving speed and a direction. Then, the steering angle and the rotation speed of each wheel are controlled by a conditional equation that is suited for steering and driving (rotation) according to the steering mode selected by the driver. 
         [0020]    However, the above technology (the mechanism that allows wheels to be steered by 90 degrees) is found difficult to achieve in reality due to the following limitations. 
         [0021]    To make the wheels steerable by 90 degrees, a more complex linking mechanism is required to steer the wheels. This results in an increase in weight or a decrease in durability. Another problem is that, to make the wheels steerable by 90 degrees, electrical cabling and hydraulic piping become complicated, and interferences and repeated stresses during steering become unavoidable. This, in turn, results in lower reliability. 
         [0022]    In addition, to give a steering angle of 90 degrees to the wheels, it is necessary to increase the operation amount of the known actuator. Therefore, the size of the actuator increases, further increasing weight and parts cost thereof. Furthermore, to make the wheels steerable by 90 degrees, a large space is required for moving the steered wheels; therefore, ensuring such a required space within the vehicle becomes another issue. 
         [0023]    Considering these problems, a steering angle which can be given to each wheel is limited to approximately 45 degrees. With such a limited steering angle, only a movement such as one shown in  FIG. 15C  is possible. This cannot be considered as an effective solution to the difficulty in parallel parking. In other words, the related-art technologies do not allow the vehicle  100  to be turned at an angle that is larger than the maximum angle at which the wheels can be steered. 
         [0024]    Furthermore, in a controlling apparatus, such as in one disclosed in Japanese Patent Application Publication No. JP-A-2001-180407, each wheel is steered and driven under a control triggered by the driver selecting the steering mode or setting the driving speed or direction. However, because extremely complex and delicate operations are required to turn a vehicle by steering and rotating the wheels independently, a human error could result in an accident (scraping or collision). 
         [0025]    For example, because the driver selects one steering mode from a plurality of steering modes, there is a chance that the driver chooses an inappropriate steering mode. In addition, if the driver is not sufficiently aware of the surroundings, the driver would choose a wrong steering mode, or an incorrect driving speed or direction. As a result, the controlling apparatus of the Japanese Patent Application Publication No. JP-A-2001-180407 ends up controlling the electric vehicle inappropriately, possibly causing an accident of the vehicle. 
         [0026]    Furthermore, the controlling apparatus disclosed in the Japanese Patent Application Publication No. JP-A-2001-180407 requires a driver operation. Therefore, the driver is required to follow cumbersome procedures, such as selecting a steering mode out of a plurality of steering modes, and must be careful to avoid misoperations, which imposes a psychological burden. 
       SUMMARY OF THE INVENTION 
       [0027]    In view of the foregoing, an advantage of some aspects of the present invention is to provide a controlling apparatus that enables a vehicle to be turned in an angle that is at least larger than the maximum angle at which the wheels can be steered, and also to provide a vehicle having the controlling apparatus. Taking the problems described above into account, another advantage of some aspects of the present invention is to provide a controlling apparatus that drives a vehicle to make an appropriate turn depending on the surrounding environment without requiring a driver to follow cumbersome procedures, and also to provide a vehicle having such a controlling apparatus. 
         [0028]    In view of the foregoing, a controlling apparatus according to a first aspect of the present invention controls a vehicle having a plurality of steerable wheels, an actuator unit that drives to steer each of the steerable wheels independently, and a wheel driving unit that drives to rotate each of the steerable wheels independently, the vehicle being moved in a given direction by operating the actuator unit and the wheel driving unit controlling steering and rotation of the steerable wheels, and the controlling apparatus includes: a first operating section that operates the actuator unit so as to give at least one of the steerable wheels a steering angle; and a second operating section that operates the wheel driving unit so as to drive to rotate at least two of the steerable wheels including the wheel to which the steering angle is given, and rotate at least one of the steerable wheels in a forward direction, and at least another of the steerable wheels in a reverse direction. The vehicle is controlled to move in a direction toward an angle that is at least larger than the maximum steerable angle of the wheels by combining a longitudinal vector component and a lateral vector component of a driving force generated by driving to rotate the wheels. 
         [0029]    According to a second aspect of the present invention, in the controlling apparatus according to the first aspect, the second operating section operates the wheel driving unit so that a sum of the lateral vector component of the driving force generated by at least two of the wheels that are driven to rotate by the wheel driving unit exceeds 0, and a sum of the longitudinal vector component thereof becomes 0. 
         [0030]    According to a third aspect of the present invention, in the controlling apparatus according to the first or second aspect, the steerable wheels include a front-right wheel, a front-left wheel, a rear-right wheel, and a rear-left wheel; the first operating section operates the actuator unit so as to give at least one of the front-right and front-left wheels and at least one of the rear-right and rear-left wheels an steering angle; and the second operating section operates the wheel driving unit so that the lateral vector component of a driving force generated by the front-right and front-left wheels becomes the same in magnitude and direction as the lateral vector component of a driving force generated by the rear-right and rear-left wheels, and that the longitudinal vector component of a driving force generated by the front-right and front-left wheels becomes the same in magnitude but different in direction as the longitudinal vector component of a driving force generated by the rear-right and rear-left wheels. 
         [0031]    According to a fourth aspect of the present invention, in the controlling apparatus according to the first or second aspect, 
         [0032]    the steerable wheels include a front-right wheel, a front-left wheel, a rear-right wheel, and a rear-left wheel; the wheel driving unit is driven so that a lateral vector component of a driving force generated by one of either the front-right and front-left wheels or the rear-right and rear-left wheels becomes greater in magnitude in the same or a different direction than a lateral vector component of a driving force generated by the other of either the front-right and front-left wheels or the rear-right and rear-left wheels; a longitudinal vector component of the driving force generated by one of either the front-right and front-left wheels or the rear-right and rear-left wheels becomes greater in magnitude in a different direction than a longitudinal vector component of a driving force generated by the other of either the front-right and front-left wheels or the rear-right and rear-left wheels; and the lateral vector component of the driving force generated by the front-right wheel, the front-left wheel, the rear-right wheel, and the rear-left wheel to spin the vehicle in rotation is cancelled out by the longitudinal vector component of the driving force generated by the front-right wheel, the front-left wheel, the rear-right wheel, and the rear-left the wheel. 
         [0033]    According to a fifth aspect of the present invention, the controlling apparatus according to any one of the first to fourth aspects further includes: a detecting section that detects usage frequency of the steerable wheels; a determining section that determines if the usage frequency detected by the detecting section exceeds a reference value; and a prohibiting section that prohibits any wheel whose usage frequency is determined to exceed the reference value by the determining section from being driven in rotation via an operation of the wheel driving unit by the second operation section. 
         [0034]    A vehicle according to a sixth aspect of the present invention includes: a plurality of steerable wheels. an actuator unit that steers each of the steerable wheels independently. a wheel driving unit that drives to rotate each of the steerable wheels independently. and the controlling apparatus according to any one of the first to fifth aspects of the present invention. 
         [0035]    A controlling apparatus according to a seventh aspect of the present invention that controls an actuator unit that drives to steer a plurality of steerable wheels of a vehicle independently, includes: an environment information obtaining section that obtains information about the environment surrounding the vehicle, a turning pattern searching section that searches a turning axis and a turning pattern for turning the vehicle based on the environment information obtained by the environment information obtaining section, and a turn controlling section that controls the actuator unit so that the vehicle is turned around the turning axis following the turning pattern, both of which are searched by the turning pattern searching section. 
         [0036]    According to an eighth aspect of the present invention, the controlling apparatus according to the seventh aspect further includes: a turning pattern storage section that stores a plurality of turning patterns, and a comparing section that compares the turning patterns stored in the turning pattern storage section with the environment information obtained by the environment information obtaining section. The turning pattern searching section searches a turning pattern from the turning pattern storage section based on a comparison result obtained by the comparing section. 
         [0037]    According to a ninth aspect of the present invention, the controlling apparatus according to the seventh or eighth aspect further includes: a driver-operated turnability determining section that determines if the vehicle is turnable under the environment information obtained by the environment information obtaining section by steering at least some of the wheels by an angle determined by a driver steering a steering wheel, and by applying a driving force determined by the driver operating a gas pedal to at least some of the wheels, and a search prohibiting section that prohibits the turning pattern searching section from searching the turning axis and the turning pattern when the driver-operated turnablilty determining section determines that the vehicle is turnable by the driver operating the steering wheel and the gas pedal. 
         [0038]    According to a tenth aspect of the present invention, the controlling apparatus according to any one of the seventh to ninth aspects further includes: a vehicle position obtaining section that obtains information about the position of the vehicle; a map data storage section that stores therein a map data; a premise-shape recognizing section that recognizes the shape of an area surrounding the vehicle whose position information is obtained by the vehicle position obtaining section, based on the map data stored in the map data storage section; and 
         [0039]    a movable area detecting section that detects an area available for the vehicle to track based on the shape of the area recognized by the premise-shape recognizing section. The environment information obtaining section obtains the area detected by the movable area detecting section as the environment information. 
         [0040]    According to an eleventh aspect of the present invention, the controlling apparatus according to any one of the seventh to tenth aspects further includes an obstacle information obtaining section that obtains information about obstacles existing in proximity to the vehicle. The environment information obtaining section obtains the obstacle information detected by the obstacle information obtaining section as the environment information. 
         [0041]    According to a twelfth aspect of the present invention, the controlling apparatus according to any one of the seventh to eleventh aspects further includes a road width storage section that stores therein road width information. The environment information obtaining section uses the road width information stored in the road width storage section as the environment information. 
         [0042]    A vehicle according to a thirteenth aspect of the present invention includes: a plurality of steerable wheels, an actuator unit that drives to steer each of the steerable wheels independently, a wheel driving unit that drives to rotate each of the steerable wheels independently, and the controlling apparatus according to any one of the seventh to twelfth aspects of the present invention. 
         [0043]    The controlling apparatus according to the first aspect of the present invention includes: a first operating section that operates the actuator unit so as to give at least one of the steerable wheels a steering angle; and a second operating section that operates the wheel driving unit so as to drive to rotate at least of the steerable wheels including the wheel to which the steering angle is given, and rotate at least one of the steerable wheels in a forward direction, and at least another of the steerable wheels in a reverse direction. Therefore, the vehicle can be advantageously moved by an angle that is at least larger than the maximum steerable angle of the wheels, by spinning each wheel driven to rotate against the road surface and combining the longitudinal vector component and the lateral vector component of a driving force generated by the wheels. Therefore, parallel parking can be achieved more easily, compared with a conventional vehicle whose movement is limited by the maximum steerable angle of the wheels. 
         [0044]    In the controlling apparatus according to the second aspect of the present invention, the second operating section operates the wheel driving unit so that a sum of the lateral vector component of the driving force generated by at least two of the wheels that are driven to rotate by the wheel driving unit exceeds 0, and a sum of the longitudinal vector component thereof becomes 0. Therefore, in addition to the advantage of the first aspect of the present invention, a vehicle can be parallel-moved laterally by spinning each wheel against the road surface even if the steerable angle of its wheels is limited to an angle less than 90 degrees. Therefore, the driver can parallel park the vehicle easily even when a road width or a spacing in the front or back of the vehicle in the parking space is extremely limited. 
         [0045]    If a vehicle can be parallel moved laterally as described above, even with the wheels with a steerable angle of less than 90 degrees (for example, 45 degrees), there are other advantages as described below, compared with a known vehicle having wheels that are steerable by 90 degrees. 
         [0046]    The linking mechanism for steering wheels may be simplified. Therefore, weight can be reduced, and durability can be improved. In addition, because the electrical cabling or hydraulic piping can be simplified, interferences or repeated stresses can be avoided to improve reliability. 
         [0047]    Moreover, it is not necessary to increase the operation amount of the known actuator. Therefore, the actuator can be prevented from increasing in size, as well as weight and parts cost thereof. Furthermore, a large space is not required for wheels to move upon being steered. Therefore, the vehicle can be prevented from increasing in size, and a space within the vehicle can be saved. 
         [0048]    In the controlling apparatus according to the third aspect of the present invention, the steerable wheels include a front-right wheel, a front-left wheel, a rear-right wheel, and a rear-left wheel. The first operating section operates the actuator unit so as to give at least one of the front-right and front-left wheels and at least one of the rear-right and rear-left wheels a steering angle. The second operating section operates the wheel driving unit so that the lateral vector component of a driving force generated by the front-right and front-left wheels becomes the same in magnitude and direction as the lateral vector component of a driving force generated by the rear-right and rear-left wheels, and that the longitudinal vector component of a driving force generated by the front-right and front-left wheels becomes the same in magnitude but different in direction as the longitudinal vector component of a driving force generated by the rear-right and rear-left wheels. Consequently, the controlling apparatus allows the lateral vector component of the driving force to be applied equally to the front side (that is, the front wheels) and the rear side (that is, the rear wheels) of the vehicle. Therefore, in addition to the advantages according to the first or the second aspect of the present invention, it is possible to prevent the generation of a force that spins the vehicle in rotation, thereby achieving a stable parallel motion. 
         [0049]    In the controlling apparatus according to the fourth aspect of the present invention, the steerable wheels include a front-right wheel, a front-left wheel, a rear-right wheel, and a rear-left wheel. The wheel driving unit is driven so that a lateral vector component of a driving force generated by one of either the front-right and front-left wheels or the rear-right and rear-left wheels becomes greater in magnitude in the same or a different direction than a lateral vector component of a driving force generated by the other of either the front-right and front-left wheels or the rear-right and rear-left wheels; 
         [0050]    a longitudinal vector component of the driving force generated by one of either the front-right and front-left wheels or the rear-right and rear-left wheels becomes greater in magnitude in a different direction than a longitudinal vector component of a driving force generated by the other of either the front-right and front-left wheels or the rear-right and rear-left wheels; and 
         [0051]    the lateral vector component of the driving force generated by the front-right wheel, the front-left wheel, the rear-right wheel, and the rear-left wheel to spin the vehicle in rotation is cancelled out by the longitudinal vector component of the driving force generated by the front-right wheel, the front-left wheel, the rear-right wheel, and the rear-left wheel. Therefore, in addition to the advantages according to the first or second aspect of the present invention, even if the lateral vector component of the driving force cannot be applied equally to the front side (that is, the front wheels) and the rear side (that is, the rear wheels) of the vehicle, it is still possible to advantageously cancel out the force to spin the vehicle in rotation, while maintaining the lateral vector component. Thus, a stable parallel motion is achieved. 
         [0052]    In the controlling apparatus according to the fifth aspect of the present invention, the detecting section detects usage frequency of the steerable wheels, the determining section determines if the usage frequency detected by the detecting section exceeds a reference value, and the prohibiting section prohibits any wheel whose usage frequency is determined to exceed the reference value by the determining section from being driven in rotation. Therefore, the wheels are prevented from being used more frequently than the others, further preventing some wheels from wearing out sooner than the others. In other words, in addition to the advantages according to any one of the first to fourth aspects of the present invention, it is possible to control the wheels to be worn out equally, and to improve the life of the vehicle as a whole. 
         [0053]    The vehicle according to the sixth aspect of the present invention includes the controlling apparatus according to any one of the first to fifth aspects of the present invention. Therefore, the vehicle has the same advantage as in any one of the first to fifth aspects of the present invention. 
         [0054]    In the controlling apparatus according to the seventh aspect of the present invention, the turning pattern searching section searches a turning axis and a turning pattern for turning the vehicle based on the environment information obtained by the environment information obtaining section. The turn controlling section controls driving of the actuator unit to steer the wheels so that the vehicle is turned around the searched turning axis following the searched turning pattern. 
         [0055]    In this manner, the turning axis and the turning pattern are searched appropriately depending on the surrounding environment of the vehicle, and each wheel is controlled so as to be steered independently to turn the vehicle based on the searched turning pattern around the searched axis. Therefore, even if the driver finds it difficult to make a turn by operating the steering wheel and the gas pedal because of the environment surrounding the vehicle, or even if there is only limited space for making a turn, the vehicle can be turned properly. Because the driver does not have to turn the steering wheel back and forth, the vehicle can advantageously make a turn safely and easily. 
         [0056]    Because each wheel is controlled so as to be steered independently to turn the vehicle based on the turning pattern around the axis that are suitable for the surrounding environment, the wheels can be steered appropriately without requiring any burden to the driver. Therefore, the vehicle can advantageously be turned appropriately. 
         [0057]    For example,  FIGS. 25B ,  26 B,  27 B and  28 B show examples corresponding to  FIGS. 25A ,  26 A,  27 A and  28 A where the driver cannot drive the vehicle  100  out of the parking lot by making a left turn in a forward direction around the turning axis A 1 , B 1 , or C 1  with a minimum turning radius (5.8 meters) using the steering wheel and the gas pedal. 
         [0058]    As shown in  FIG. 25B , the vehicle  1  can be turned without scraping the wall  120   a  because the turn controlling section controls the steering and the rotation of each wheel by way of the actuators and the wheel driving unit so that the vehicle  1  is turned around the turning axis A 2 , which is detected by the turning pattern searching section based on the information about the environment around the vehicle  1 . 
         [0059]    In a similar manner, as shown in  FIGS. 26B and 27B , the vehicle  1  can be turned without scraping the vehicle  130  parked in an adjacent parking space or the vehicle  140  parked in front of the vehicle  1 , because the turn controlling section controls the steering and the rotation of each wheel by way of the actuator unit and the wheel driving unit so that the vehicle  1  is turned around the turning axes B 2  and C 2 , respectively, which are detected by the turning pattern searching section based on the environment surrounding the vehicle  1 . 
         [0060]      FIG. 28B  shows an example corresponding to  FIG. 28A . In  FIG. 28A , the driver is driving the vehicle  100  out from the parking lot to the roadway  160  by making a left turn in a forward direction around the turning axis D 1  with a minimum turning radius (5.8 meters) using the steering wheel and the gas pedal, causing a dangerous situation because the vehicle  100  overruns the center line  180 . 
         [0061]    Because the turn controlling section controls the steering and the rotation of each wheel by way of the actuator unit and the wheel driving unit so that the vehicle  1  is turned around the turning axis D 2 , which is searched by the turning pattern searching section based on the environment surrounding the vehicle  1 , the vehicle  1  can make a turn without overrunning the center line  180 , as shown in  FIG. 28B . 
         [0062]    The environment information obtained by the environment information obtaining section includes vehicle position information obtained, for example, by the global positioning system (GPS); information about environment around the vehicle, such as the shape of the premise or the road width where the vehicle can be moved, obtained from the map data or parking lot information; and information about obstacles in proximity to the vehicle, captured by cameras or detected by sensors. 
         [0063]    The turning pattern searching section for searching the turning axes or the turning patterns may employ, for example: a method that selects an available vehicle turning pattern from a memory that stores a plurality of turning patterns (data including the swept path of each wheel, widths in the lateral and longitudinal directions required to turn the vehicle) corresponding to a turning axis; or a method that searches an appropriate vehicle turning pattern from an infinite number of turning axes around the vehicle by simulation by computation. 
         [0064]    In the controlling apparatus according to the eighth aspect of the present invention, the comparing section compares the turning patterns stored in the turning pattern storage section with the environment information obtained by the environment information obtaining section, and the turning pattern searching section searches a turning pattern from the turning pattern storage section based on the comparison result. Because an optimum turning pattern is selected from a predetermined number of the turning patterns, the vehicle can be advantageously turned with the optimum turning axis with a minimal control burden, in addition to the advantage of the controlling apparatus according to the seventh aspect of the present invention. 
         [0065]    In the controlling apparatus according to the ninth aspect of the present invention, the driver-operated turnability determining section determines if the vehicle turnable under the environment information obtained by the environment information obtaining section by steering at least some of the wheels by an angle determined by a driver steering a steering wheel, and by applying a driving force determined by the driver operating a gas pedal to at least some of the wheels; and the search prohibiting section prohibits the turning pattern searching section from searching the turning axis and the turning pattern when the driver-operated turnability determining section determines that the vehicle is turnable by the driver operating the steering wheel and the gas pedal. Therefore, in addition to the advantages according to the seventh or eight aspect of the present invention, if the surrounding environment allows the driver to make a turn using the steering wheel and the gas pedal, the turning pattern searching section is advantageously prohibited from searching a turning axis or a turning pattern. As a result, the driver makes a turn by manually operating the steering wheel and the gas pedal. 
         [0066]    Upon steering and rotating each wheel independently, the wheels often slip. Therefore, the wheels wear out more if each wheel is steered and rotated independently, compared with when the vehicle is turned by the driver operating the steering wheel and the gas pedal. Therefore, if the surrounding environment allows the driver to make a turn using the steering wheel and the gas pedal, the turn is made by the driver operating the steering wheel and the gas pedal. In this manner, the wheels can be advantageously suppressed from wearing out. 
         [0067]    In the controlling apparatus according to the tenth aspect of the present invention, the premise-shape recognizing section recognizes the shape of an area surrounding the vehicle whose position information obtained by the vehicle position obtaining section, based on the map data stored in the map data storage section, and the movable area detecting section detects an area available for the vehicle to track based on the shape of the thus-recognized area, and the environment information obtaining section obtains the area detected by the movable area detecting section as the environment information. As a result, in addition to the advantages according to any one of the seventh to ninth aspects of the present invention, the turning pattern searching section can advantageously search a turning axis and a turning pattern using the area information detected by the movable area detecting section as the environment information. 
         [0068]    Because it is possible to precisely recognize the shape of the premise surrounding the vehicle based on the map data using the obtained vehicle position information, the area available for the vehicle to track (movable area) can be also detected precisely. As a result, it is possible to advantageously search a tuning pattern that does not make the vehicle overrun the detected movable area. 
         [0069]    The movable area (the area vehicle can be moved) detected by the movable area detecting section, may be equal to or smaller than the premise shape that is recognized by the premise-shape recognizing section. 
         [0070]    For example, if the map data includes information such as shapes and positions of a building or a wall, the information about potential obstacles, such as the building or the wall, may be excluded from the premise shape, which is determined by premise-shape recognizing section, to obtain a movable area. If the map data includes information about a parking lot, the information about parking spaces in the lot, except for a space reserved for this vehicle, may be excluded from the movable area. If the premise-shape information, recognized by the premise-shape recognizing section, includes road information, the lanes legally prohibited from driving (in Japan, right lanes in the driving direction with respect to the center line) may be excluded from the movable area. 
         [0071]    In the controlling apparatus according to the eleventh aspect of the present invention, the obstacle information obtaining section obtains information about obstacles in proximity to the vehicle, and the environment information obtaining section obtains the obstacle information detected by the obstacle information obtaining section as the environment information. As a result, in addition to the advantages according to any one of the seventh to tenth aspects of the present invention, the turning pattern searching section can search a turning axis and a turning pattern using the obstacle information detected by the obstacle information obtaining section as the environment information. 
         [0072]    By obtaining the obstacle information, the turning pattern searching section can advantageously search the turning pattern in a precise manner to avoid the obstacles indicated by the obstacle information. As a result, the vehicle can be protected against a scrape or a collision. 
         [0073]    The obstacle information obtaining section may employ: a method that obtains obstacle information based on images captured by cameras; a method that detects obstacles by a sensor or radar; and a method that obtains information about architectural structures, such as a building or a wall, from the map data and so on. If the obstacle information is obtained by images captured by the cameras, it is possible to obtain information not detectable by the sensor or radar (such as a boundary line of a parking space or a center line). If the obstacle information is obtained by the sensor or radar, it is possible to obtain information that is difficult to obtain from a static image (for example, information about other approaching vehicles on the road). 
         [0074]    In the controlling apparatus according to the twelfth aspect of the present invention, the environment information obtaining section uses the road width information stored in a road width storage section as the environment information. As a result, in addition to the advantages according to any one of the seventh to eleventh aspects of the present invention, the turning pattern searching section can advantageously search a turning axis and a turning pattern using the road width information stored in the road width storage section as the environment information. 
         [0075]    Because the turning pattern is selected based on the road width, it is advantageously possible to ensure selection of a turning pattern that prevents the vehicle from running off the road. Especially, if the road is a public roadway (road), the vehicle can be turned so that it does not run off the road width (width of the road itself or that of a one-way lane). Therefore, the vehicle can be reliably protected against scraping or colliding into other vehicles approaching from the opposite direction, ensuring safety. 
         [0076]    The vehicle according to the thirteenth aspect of the present invention includes the controlling apparatus according to any one of the seventh to twelfth aspects of the present invention. Therefore, the vehicle has the same advantages as those of the controlling apparatus according to one of the seventh to twelfth aspects of the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0077]      FIG. 1  is a schematic drawing for showing a vehicle having a controlling apparatus according to a first embodiment of the present invention; 
           [0078]      FIG. 2  is a block diagram for showing an electrical configuration of the controlling apparatus according to the first embodiment of the present invention; 
           [0079]      FIGS. 3A to 3C  are schematic drawings for showing information stored in the parallel-motion controlling table shown in  FIG. 2 ; 
           [0080]      FIG. 4  is a flowchart for showing a main process; 
           [0081]      FIG. 5  is a flowchart for showing an updating process of a movement-direction memory; 
           [0082]      FIG. 6  is a flowchart for showing a process of a parallel-motion control; 
           [0083]      FIG. 7  is a flowchart for showing a process for storing a wheel-spin count; 
           [0084]      FIGS. 8A to 8C  are schematic drawings for showing information stored in a parallel-motion controlling table according to a second embodiment of the present invention; 
           [0085]      FIGS. 8D to 8F  are schematic drawings for showing information stored in a parallel-motion controlling table according to a third embodiment of the present invention; 
           [0086]      FIGS. 9A to 9C  are schematic drawings for showing information stored in a parallel-motion controlling table according to a fourth embodiment of the present invention; 
           [0087]      FIGS. 9D to 9F  are schematic drawings for showing information stored in a parallel-motion controlling table according to a fifth embodiment of the present invention; 
           [0088]      FIGS. 9G to 9I  are schematic drawings for showing information stored in a parallel-motion controlling table according to a sixth embodiment of the present invention; 
           [0089]      FIGS. 10A and 10B  are schematic drawings for showing information stored in a parallel-motion controlling table according to seventh and eighth embodiments, respectively, of the present invention; 
           [0090]      FIGS. 11A and 11B  are schematic diagram for explaining a ninth embodiment of the present invention; 
           [0091]      FIGS. 11C and 11D  are schematic drawings for showing information stored in a parallel-motion controlling table according to the ninth embodiment of the present invention; 
           [0092]      FIGS. 12A to 12I  are schematic drawings for showing variations of the information stored in the parallel-motion controlling table according to the ninth embodiment of the present invention; 
           [0093]      FIGS. 13A to 13I  are schematic drawings for showing alternative variations of the information stored in the parallel-motion controlling table according to the ninth embodiment of the present invention; 
           [0094]      FIGS. 14A to 14C  are schematic drawings for showing information stored in the parallel-motion controlling table according to a tenth embodiment of the present invention; 
           [0095]      FIGS. 15A to 15  C are schematic top views showing a related-art technology of parallel parking a vehicle; 
           [0096]      FIG. 16  is a schematic drawing for showing a vehicle provided with a controlling apparatus according to an eleventh embodiment of the present invention; 
           [0097]      FIG. 17  is a block diagram for showing an electrical configuration of the controlling apparatus according to the eleventh embodiment of the present invention; 
           [0098]      FIG. 18  is a schematic diagram for showing a structure of turn controlling tables; 
           [0099]      FIG. 19  is a schematic drawing for explaining twenty representative turning axes selected for a front-left turn according to the eleventh embodiment of the present invention; 
           [0100]      FIG. 20  is a schematic diagram for explaining a protruding length Ex in the x-direction and a protruding length Ey in the y-direction; 
           [0101]      FIG. 21  is a bar graph for showing vehicle turning patterns corresponding to the twenty turning axes recorded in the front-left turn controlling table shown in  FIG. 18 ; 
           [0102]      FIG. 22  is a flowchart for showing a turning control process; 
           [0103]      FIG. 23  is a flowchart for showing a surrounding environment recognizing process; 
           [0104]      FIG. 24  is a flowchart for showing a turning control process according to a twelfth embodiment of the present invention; 
           [0105]      FIG. 25A  is a diagram for explaining an example of a problem upon making a turn with a conventional vehicle; 
           [0106]      FIG. 25B  is a diagram for explaining the effect of a vehicle and a controlling apparatus of the present invention; 
           [0107]      FIG. 26A  is a diagram for explaining an example of another problem upon making a turn with a conventional vehicle; 
           [0108]      FIG. 26B  is a diagram for explaining an advantageous effect of a vehicle and a controlling apparatus of the present invention; 
           [0109]      FIG. 27A  is a diagram for explaining an example of another problem upon making a turn with a conventional vehicle; 
           [0110]      FIG. 27B  is a diagram for explaining an advantageous effect of a vehicle and a controlling apparatus of the present invention; 
           [0111]      FIG. 28A  is a diagram for explaining an example of another problem upon making a turn with a conventional vehicle; and 
           [0112]      FIG. 28B  is a diagram for explaining an advantageous effect of a vehicle and a controlling apparatus of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0113]    Exemplary embodiments of the present invention are explained herein with reference to the attached drawings.  FIG. 1  is a schematic drawing for showing a vehicle  1  having a controlling apparatus  10  according to a first embodiment of the present invention. An arrow FWD in  FIG. 1  indicates a forward direction of the vehicle  1 . In  FIG. 1 , each wheel  2  is shown steered by a given angle. 
         [0114]    To begin with, a general structure of the vehicle  1  is explained herein. As shown in  FIG. 1 , the vehicle  1  includes a body frame BF, the plurality of wheels  2  (four wheels in the first embodiment of the present invention) supported by the body frame BF, a wheel driving unit  3  that operates each wheel  2  in rotation independently, and an actuator unit  4  that operates to steer each wheel  2  independently. 
         [0115]    Normally, the vehicle  1  can be moved in straight in a forward or backward direction (upward or downward directions in  FIG. 1 ) by rotating all of the wheels  2  in the same direction, or the vehicle  1  can be turned by changing the steering angle of each wheel  2 . 
         [0116]    According to the present invention, the vehicle  1  can be also moved in parallel in the lateral directions (toward the right and left directions in  FIG. 1 ) in a sliding manner with respect to the road surface. This movement is called “a parallel-motion”, which is to be described in details hereinafter. This movement is achieved by arranging each wheel  2  in a given position (hereinafter, “parallel-motion position”) and driving all or some of the wheels  2  in a rotating motion (see  FIGS. 3A to 3C ). 
         [0117]    Each components included in the vehicle  1  is described in details herein. As shown in  FIG. 1 , the wheels  2  include four wheels: a front-left wheel  2 FLW and a front-right wheel  2 FRW located at the front side of the vehicle  1  with respect to the driving direction, and a rear-left wheel  2 RLW and a rear-right wheel  2 RRW located at the rear side of the vehicle  1  with respect to the driving direction. These wheels  2 FLW to  2 RRW can be steered by steering units  20 ,  30 . 
         [0118]    The steering units  20 ,  30  are provided to steer each of the wheels  2 , and mainly include kingpins  21 , tie rods  22 , and articulating mechanisms  23 , respectively, as shown in  FIG. 1 . Each of the kingpins  21  supports each wheel  2  so as to allow a pivoting movement thereof, and each of the tie rods  22  is linked to a knuckle arm (not shown) provided for each wheel  2 . The articulating mechanism  23  is provided to articulate a driving force of the actuator  4  to the tie rod  22 . 
         [0119]    As described above, the actuator unit  4  is a driving/steering mechanism that operates to steer each wheel  2  independently. As shown in  FIG. 1 , the actuator unit  4  includes four actuators,  4 FLA to  4 RRA, respectively located at the front-right, front-left, rear-right, and rear left of the vehicle. When a driver turns a steering wheel  51 , all or some (for example, only those for the front wheels  2 FLW,  2 FRW) of the actuators  4 FRA to  4 RLA are driven to steer the wheels  2  by an angle determined by a degree that a driver steers the steering wheel  51 . 
         [0120]    The operation of the actuator unit  4  is also triggered when the driver operates a parallel-motion switch  54 . To prepare for the parallel-motion control, the actuator unit  4  positions each wheel  2  in its parallel-motion position by steering each wheel  2  by a given angle determined by operations of the parallel-motion switch  54  (see  FIGS. 3A to 3C , for example). Details of the parallel-motion control are to be described hereinafter. 
         [0121]    According to the first embodiment of the present invention, the front-left to rear-right actuators  4 FLA to  4 RRA are implemented as electrical motors, and the articulating mechanisms  23  are implemented as screws. When the electrical motor is rotated, the rotating movement thereof is converted into a liner movement by the articulating mechanism  23 , and articulated to the tie rod  22 . As a result, the wheel  2  is driven to pivot around the kingpin  21 , and is steered by a given angle. 
         [0122]    The wheel driving unit  3  is provided to rotate each wheel  2  independently. As shown in  FIG. 1 , the wheel driving unit  3  includes four electrical motors (front-left to rear-right motors,  3 FLM to  3 RRM, respectively), one for each wheel  2  (as an in-wheel motor). When the driver operates a gas pedal  53 , each wheel driving unit  3  applies a driving force to each wheel  2 , and the wheel  2  is rotated at a speed determined by how far the gas pedal  53  was stepped on by the driver. 
         [0123]    The wheel driving unit  3  is also operated when a driver operates the parallel-motion switch  54 . The parallel-motion control is performed by driving each wheel  2  in a rotating motion independently at a speed determined by operations of the parallel-motion switch  54  and the gas pedal  53  (see  FIGS. 3A to 3C  for example). Details of the parallel-motion control are to be described hereinafter. 
         [0124]    The controlling apparatus  10  is responsible for overall control of each structural element of the vehicle  1  described above. For example, the controlling apparatus  10  performs the parallel-motion control by controlling a steering angle and a rotation speed of each wheel  2  by way of the corresponding actuator  4  and wheel driving unit  3 . Details about a structure of the controlling apparatus  10  are described herein with reference to  FIG. 2 . 
         [0125]      FIG. 2  is a block diagram for showing an electrical configuration of the controlling apparatus  10 . As shown in  FIG. 2 , the controlling apparatus  10  includes a CPU  71 , a ROM  72 , a RAM  73 , and an EEPROM  74 , each of which is connected to an input-output port  76  via a bus line  75 . The units, such as the wheel driving unit  3 , are connected to the input-output port  76 . 
         [0126]    The CPU  71  is a processor that controls each unit connected via the bus line  75 . The ROM  72  is a non-writable, nonvolatile memory, and controlling programs executed by the CPU  71  or fixed value data, for example, are stored therein. The RAM  73  is a memory that stores various data in a writable fashion while the controlling programs are being executed. The EEPROM  74  is a writable, nonvolatile memory, and can store data persistently without a backup power supply, even after the controlling apparatus  10  is turned off. 
         [0127]    As shown in  FIG. 2 , the ROM  72  includes a parallel-motion controlling table  72   a . In the parallel-motion controlling table  72   a , information used in the parallel-motion control is recorded, such as the parallel-motion position (steering position), a direction and a rate of rotation of each wheel  2 . The parallel-motion controlling table  72   a  is explained in more details with reference to  FIGS. 3A to 3C . 
         [0128]      FIGS. 3A to 3C  are schematic drawings for showing the information stored in the parallel-motion controlling table  72   a . It should be noted that  FIGS. 3A to 3C  show only a part of the information stored in the parallel-motion controlling table  72   a ; that is, only the pattern information for moving the vehicle  1  to the right. In other words, the pattern information for moving the vehicle  1  to the left is omitted herein. The pattern shown in  FIG. 3A  corresponds to a normal mode (see step S 33  in  FIG. 6 ), and that shown in  FIGS. 3B and 3C  correspond to a saving mode (see step S 34  in  FIG. 6 ), respectively to be explained hereinafter. 
         [0129]    Thickness of the arrows in  FIGS. 3A to 3C  indicates a relative rate at which each wheel  2  is rotated upon the parallel-motion control. In other words, a wheel with a thick arrow is rotated at a higher rate in relation to a rotation rate of a wheel with a thin arrow. An absolute value of the rotation rate is in proportion to a degree the gas pedal  53  is operated by the driver. In the patterns shown in  FIGS. 3A to 3C , each arrow has the same thickness. This means that each wheel  2  is controlled to be rotated at the same speed. 
         [0130]    A color of the arrows in  FIGS. 3A to 3C  indicates a direction in which each wheel  2  is rotated in the parallel-motion control. A white arrow indicates a rotation in the forward direction, and a black arrow indicates a rotation in the reverse direction. A wheel  2  without any arrow is not driven (prohibited from being driven) in rotation during the parallel-motion control. 
         [0131]    Upon performing the parallel-motion control, the CPU  71  reads information corresponding to each wheel  2  from the parallel-motion controlling table  72   a , such as the parallel-motion position, rotation direction, and rotation speed thereof. Based on the read information, the CPU  71  controls the actuator unit  4  and the wheel driving unit  3 . By the actuator unit  4  and the wheel driving unit  3  being controlled, the wheels  2  are moved to their parallel-motion positions and rotated at a predetermined speed, and the vehicle  1  is parallel-moved in a lateral direction. 
         [0132]    For example,  FIG. 3A  suggests that following information is recorded in the parallel-motion controlling table  72   a  as control data: steer the front wheels  2 FLW,  2 FRW toward right; steer the rear wheels  2 RLW,  2 RRW toward left; steer each wheel  2  by an angle of the same absolute value (steered by 45 degrees in the first embodiment of the present invention); rotate the front wheels  2 FLW,  2 FRW to forward; rotate the rear wheels  2 RLW,  2 RRW to reverse; and rotate each wheel  2  at the same rotation rate (speed). 
         [0133]    When it is determined that the pattern of  FIG. 3A  is to be used for the parallel-motion control (see step S 32  in  FIG. 6 ), the CPU  71  reads the pattern (control data, such as a direction to steer the wheels  2 , an absolute value for the steered angle, or a direction and a speed to rotate each wheel  2 ) from the parallel-motion controlling table  72   a , and controls the actuator unit  4  and the wheel driving unit  3  based on the pattern (see steps S 37  and S 38  in  FIG. 6 ). 
         [0134]    By this control, the wheels  2  of the vehicle  1  are steered to the positions shown in  FIG. 3A  (their respective parallel-motion position). When a driver steps on the gas pedal  53 , each wheel  2  is driven to rotate in the specified direction at a speed determined by a degree the gas pedal  53  is stepped on (see step S 36  in  FIG. 6 ). 
         [0135]    In this manner, the wheels  2  spin on the road surface, because the vector component in the forward direction (upward direction in  FIG. 3A ) generated by the front wheels  2 FLW,  2 FRW is cancelled out by the vector component in the backward direction (downward direction in  FIG. 3A ) generated by the rear-right and rear-left wheels  2 RLW,  2 RRW. At the same time, the vector components toward right (the right direction in  FIG. 3A ) generated by the front wheels  2 FLW,  2 FRW and by the rear wheels  2 RLW,  2 RRW together function as a driving force to move the vehicle  1  to the right. As a result, the vehicle  1  is parallel-moved to the right (right direction in  FIG. 3A ). 
         [0136]      FIG. 3B  suggests that following information is stored in the parallel-motion controlling table  72   a  as control data: steer the front wheels  2 FLW,  2 FRW toward right; steer the rear wheels  2 RLW,  2 RRW toward left; steer each wheel  2  by an angle of the same absolute value (steered by 45 degrees in the first embodiment of the present invention); rotate the front-right wheel  2 FRW to forward; rotate the rear-right wheel  2 RRW backward; rotate the right wheels  2 FRW,  2 RRW at the same rotation rates (speed); and prohibit the left wheels  2 FLW,  2 RLW from being rotated. 
         [0137]    For example, if the parallel-motion control takes place using this pattern shown in  FIG. 3B , the vector component in the forward direction (upward direction in  FIG. 3B ) generated by the front-right wheel  2 FRW is cancelled out by the vector component in the backward direction (downward direction in  FIG. 3B ) generated by the rear-right wheel  2 RRW. At the same time, the vector components toward the right (right direction in  FIG. 3B ) generated by the right wheels  2 FRW,  2 RRW together function as a driving force to drive the vehicle  1  to the right. As a result, the vehicle  1  is parallel-moved to the right (right direction in  FIG. 3B ). 
         [0138]      FIG. 3C  suggests that following information is stored in the parallel-motion controlling table  72   a  as control data: steer the front wheels  2 FLW,  2 FRW toward right; steer the rear wheels  2 RLW,  2 RRW toward left; steer each wheel  2  by an angle of the same absolute value (steered by 45 degrees in the first embodiment of the present invention); rotate the front-left wheel  2 FLW to forward; rotate the rear-left wheel  2 RLW to reverse; rotate the left wheels  2 FLW,  2 RLW at the same rotation rates (speed); and prohibit the right wheels  2 FRW,  2 RRW from being rotated. 
         [0139]    For example, if the parallel-motion control takes place using this pattern shown in  FIG. 3C , the vector component in the forward direction (upward direction in  FIG. 3C ) generated by the front-left wheel  2 FLW is cancelled out by the vector component in the backward direction (downward direction in  FIG. 3C ) generated by the rear-left wheel  2 RLW. At the same time, the vector components toward the right (right direction in  FIG. 3C ) generated by the front-left wheel  2 FLW and by the rear-left wheel  2 RLW together function as a driving force to drive the vehicle  1  to the right. As a result, the vehicle  1  is parallel-moved to the right (right direction in  FIG. 3C ). 
         [0140]    Explanation is continued referring back to  FIG. 2 . The RAM  73  has a movement-direction memory  73   a  as shown in  FIG. 2 . The movement-direction memory  73   a  maintains a value corresponding to a direction that the vehicle  1  is to be moved during the parallel-motion control. The movement-direction memory  73   a  is set to one of “0”, “1”, or “2” depending on operation of the parallel-motion switch  54  and a running condition (ground speed) of the vehicle  1  (see  FIG. 7 ). The CPU  71  determines the direction to parallel-move the vehicle  1  based on the value stored in the movement-direction memory  73   a.    
         [0141]    As shown in  FIG. 2 , the EEPROM  74  has a plurality of wheel-spin count memories  74 FLMe to  74 RRMe, each corresponding to each of the front-left, front-right, rear-left, and rear-right wheels  2 FLW to  2 RRW. The wheel-spin count memories  74 FLMe to  74 RRMe respectively records the number of times each wheel  2  ( 2 FLW to  2 RRW) is used. According to the first embodiment of the present invention, the wheel-spin count memories  74 FRMe to  74 RLMe accumulatively record the number of times each wheel  2  is spun against the road surface (see  FIG. 4 ) as their usage frequency. Based on the counts stored, the CPU  71  decides whether to use the normal mode or the saving mode for the parallel-motion control (see step S 3  in  FIG. 6 ). 
         [0142]    As described above, the wheel driving unit  3  is provided to drive each wheel  2  (see  FIG. 1 ) in a rotating motion, and includes four motors  3 FLM to  3 RRM at the front-left, front-right, rear-left, and rear-right of the vehicle  1 , and a driving circuit (not shown) that controls driving of each motor  3 FLM to  3 RRM based on an instruction from the CPU  71 . 
         [0143]    As also described above, the actuator unit  4  is provided to drive each wheel  2  to be steered, and includes four actuators  4 FLA to  4 RRA at the front-right, front-left, rear-right, and rear-left of the vehicle  1 , and a driving circuit (not shown) that controls driving of each actuator  4 FLA to  4 RRA based on an instruction from the CPU  71 . 
         [0144]    A steered-angle sensor unit  31  is provided to detect a respective steered angle of each wheel  2 , and to output the detected result to the CPU  71 . The steered-angle sensor unit  31  includes four steered-angle sensors  31 FLS to  31 RRS for each wheel  2 , and a processing circuit (not shown) for processing detection results of the steered-angle sensors  31 FLS to  31 RRS and outputting processed results to the CPU  71 . 
         [0145]    According to the first embodiment of the present invention, the respective steered-angle sensor  31 FLS to  31 RRS is provided in each articulating mechanism  23 . The steered-angle sensor units  31  are implemented as non-contacting type rotation-angle sensors, which detects the number of rotations while a rotation is converted into a linear movement in the articulating mechanism  23 . Because the rotation count is proportional to the displacement of the corresponding tie rod  22 , the CPU  71  can obtain the steered angle of each wheel  2  based on the detected results (rotation counts) received from the steered-angle sensor units  31 . 
         [0146]    The steered-angle, detected by the steered-angle sensor unit  31 , is an angle enclosed by a center line laid across the diameter of the wheel  2  and a reference line laid on a side of the vehicle  1  (the body frame BF), and determined regardless of the movement direction of the vehicle  1 . 
         [0147]    A vehicle speed sensor unit  32  is provided to detect the ground speed (an absolute value and a moving direction) of the vehicle  1  with respect to a road surface and to output the detected results to the CPU  71 . The vehicle speed sensor unit  32  includes a longitudinal acceleration sensor  32   a , a lateral acceleration sensor  32   b , and a processing circuit (not shown) that processes the results detected by each acceleration sensor  32   a ,  32   b  and outputs the processed results to the CPU  71 . 
         [0148]    The longitudinal acceleration sensor  32   a  detects accelerated velocity of the vehicle  1  (the body frame BF) in the forward or backward direction (upward or downward direction in  FIG. 1 ). The lateral acceleration sensor  32   b  detects accelerated velocity of the vehicle  1  (the body frame BF) in the right or left direction (right or left directions in  FIG. 1 ). According to the first embodiment of the present invention, these acceleration sensors  32   a ,  32   b  are implemented as piezoelectric sensors using a piezoelectric element. 
         [0149]    The CPU  71  can calculate a ground speed (an absolute value and a moving direction) of the vehicle  1  by respectively obtaining a time integration (an acceleration value) of each detection result of the acceleration sensors  32   a ,  32   b  received from the vehicle speed sensor unit  32 , obtaining the velocity in each direction (longitudinal and lateral directions), and combining these two vector components. 
         [0150]    A wheel-rotation speed sensor unit  33  is provided to detect a rotation speed of each wheel  2 , and to output the detected results to the CPU  71 . The wheel-rotation speed sensor unit  33  includes four rotation speed sensors  33 FLS to  33 RRS for each wheel  2 , and a processing circuit (not shown) that processes the results detected by each of the rotation speed sensors  33 FLS to  33 RRS and outputs the processed results to the CPU  71 . 
         [0151]    According to the first embodiment of the present invention, the rotation speed sensor  33 FLS to  33 RRS is provided in the wheel  2 , respectively, and detect an angular speed of each wheel  2  as a rotation speed. In other words, the rotation speed sensors  33 FLS to  33 RRS are implemented as an electromagnetic pickup sensor with a rotating body that rotates in cooperation with the wheel  2  and a pickup that electromagnetically detects the presence of a plurality of teeth provided on the circumference of the rotating body. 
         [0152]    The CPU  71  can calculate a wheel-spin count (usage count) of each wheel  2  with respect to the road surface from following values: the rotation speed detected by the rotation speed sensors  33 FLS to  33 RRS received from the wheel-rotation speed sensor unit  33 ; an external diameter of each wheel  2 ; the steered-angle of each wheel  2  detected by the corresponding steered-angle detecting sensor unit  31 ; and the ground speed of the vehicle  1  calculated by the vehicle speed sensor unit  32 . 
         [0153]    A grounding load sensor unit  34  is provided to detect a grounding load generated between each wheel  2  and the road surface in contact therewith, and to output the detected results to the CPU  71 . The grounding-load sensor unit  34  includes four load sensors  34 FLS to  34 RRS for each wheel  2 , and a processing circuit (not shown) that processes the results detected by each of the load sensors  34 FLS to  34 RRS and outputting the processed results to the CPU  71 . 
         [0154]    According to the first embodiment of the present invention, the load sensors  34 FLS to  34 RRS are implemented as piezoresistive tri-axis load sensors. The load sensors  34 FLS to  34 RRS are provided on the suspension axis (not shown) of each wheel  2  to detect the grounding load in the longitudinal direction, the lateral direction, and the vertical direction. 
         [0155]    The CPU  71  can detect a friction factor μ of the road surface at a point in contact with each wheel  2  from the detection result (grounding load) detected by each load sensor  34 FLS to  34 RRS and received from the grounding load sensor unit  34 . 
         [0156]    The front left wheel  2 FLW is herein examined more closely as an example. If Fx is the load in the longitudinal direction, Fy is that in the lateral direction, and the Fz is that in the vertical direction respectively detected by the front-left sensor  34 FLS, the friction factor μx in the traveling direction of the vehicle  1  can be calculated by Fx/Fz; and the friction factor μy in the lateral direction of the vehicle  1  can be calculated by Fy/Fz. 
         [0157]    The parallel-motion switch  54  is provided so that the driver can instruct the controlling apparatus  10  to start or release the parallel-motion control, and to specify a direction to move the vehicle  1  using the parallel-motion control (all of which are not shown). The parallel-motion switch  54  includes an operating knob, a sensor, and a processing circuit. The operating knob allows the driver to select one out of three positions, “right”, “release”, and “left”, and is held at the selected position. The sensor detects the selected position of the operating knob. The processing circuit processes the result detected by the sensor and outputs the processed result to the CPU  71 . 
         [0158]    As described above, the CPU  71  sets one of the values “0”, “1”, and “2” to the movement-direction memory  73   a  according to the position of the parallel-motion switch  54  and the running condition (ground speed) of the vehicle  1  (see  FIG. 7 ). Upon performing the parallel-motion control, the CPU  71  also determines the direction to parallel-move the vehicle  1  based on the value stored in the movement-direction memory  73   a.    
         [0159]    An example of other input-output unit  35  shown in  FIG. 2  includes an operation condition detecting sensor unit (not shown) that detects the operation conditions of the steering wheel  51 , a brake pedal  52 , and the gas pedal  53  (for example, the rotated angle or stepped amount, or operation speed thereof) (see  FIG. 1 ). 
         [0160]    For example, when the gas pedal  53  is operated, the operation condition detecting sensor unit detects how far the gas pedal was operated, and outputs the detected degree to the CPU  71 . The CPU  71 , in turn, controls the wheel driving unit  3  according to the operated degree input from the operation condition detecting sensor unit to drive the wheels  2  in rotation. 
         [0161]    A process executed by the controlling apparatus  10  is described herein with reference to  FIGS. 4 to 7 .  FIG. 4  is a flowchart for showing a main process. The main process is repeatedly executed by the CPU  71  while the controlling apparatus  10  is powered on. 
         [0162]    In the main process, initialization takes place after the power is turned on, such as to clear the RAM  73  to “0”, and to set the initial values thereto (step S 1 ). However, in the initialization, the usage frequency data (a wheel-spin count) maintained in each wheel-spin-count memory  74 FLMe to  74 RRMe is exempted from being cleared. 
         [0163]    After initialization takes place at step S 1 , the movement-direction memory  73   a  is updated (step S 2 ). It is explained herein how the movement-direction memory  73   a  is updated with reference to  FIG. 5 .  FIG. 5  is a flowchart for showing an updating process of the movement-direction memory  73   a.    
         [0164]    Upon updating the moving direction (step S 2 ), it is determined whether the vehicle  1  is parked (step S 21 ) to determine if the vehicle  1  is in a condition that the parallel-motion control can be started, or to the direction of the parallel-motion can be changed. 
         [0165]    If it is determined at step S 21  that the vehicle  1  is parked (Yes at step S 21 ), it means that the vehicle  1  is in the condition that the parallel-motion control can be started, or the direction of the parallel-motion can be changed. Therefore, if yes (Yes at step S 21 ), the position of the parallel-motion switch  54  is detected (step S 22 ), the movement-direction memory  73   a  is updated to one of “0”, “1”, or “2” (steps S 23 , S 24 , S 25 ) according to the detected position of the parallel-motion switch  54 , and the updating process of the movement-direction memory  73   a  (step S 2 ) ends. 
         [0166]    More specifically, if the parallel-motion switch  54  is at the “left” position (Left at step S 22 ), the value maintained in the movement-direction memory  73   a  is updated to “0” (step S 23 ). If the parallel-motion switch  54  is at the “release” position (Release at step S 22 ), the value in the movement-direction memory  73   a  is updated to “1” (step S 24 ). If the parallel-motion switch  54  is at the “right” position (Right at step S 22 ), the value in the movement-direction memory  73   a  is updated to “2” (step S 25 ). 
         [0167]    In this manner, the CPU  71  can determine if the driver instructed to start the parallel-motion control to move the vehicle  1  either to the right or to the left, or to release (end) the parallel-motion control and drive normally (see  FIG. 6 ). 
         [0168]    If it is determined at step S 21  that the vehicle  1  is not parked (No at step S 21 ), it means that the vehicle  1  is now running, and it is not in the condition to start the parallel-motion control, or to change the direction of the parallel-motion. Therefore, if no (No at step S 21 ), steps S 22  to S 25  are skipped even if the position of the parallel-motion switch  54  is changed by the driver. Thus, the movement-direction updating process (step S 2 ) ends without updating the value in the movement-direction memory  73   a.    
         [0169]    In this manner, the movement-direction memory  73   a  is protected against being updated while the vehicle  1  is running, even if the driver operates the parallel-motion switch  54  carelessly. For example, the vehicle  1  is protected against being switched carelessly from a normal driving mode to the parallel-motion mode, or the direction of the parallel-motion being switched from one direction to the other while the vehicle  1  is parallel-moved. 
         [0170]    Referring back to  FIG. 4 , the process executed by the controlling apparatus  10  is further explained. After updating the movement-direction memory  73   a  at step S 2 , the parallel-motion control is executed (step S 3 ). A process of the parallel-motion control is explained herein with reference to  FIG. 6 .  FIG. 6  is a flowchart for showing the process of the parallel-motion control. 
         [0171]    Upon starting the parallel-motion control (step S 3 ), it is determined if the movement-direction memory  73   a  is set to “1” (step S 31 ). If it is determined that it is “1” (Yes at step S 31 ), it means that parallel-motion switch  54  is set to its release position (see  FIG. 5 ). Then, it is assumed that the driver has not operated the parallel-motion switch  54  yet, or a desired parallel-motion has been completed and the driver instructed to release (end) the parallel-motion control. 
         [0172]    Therefore, if it is set to “1” (Yes at step S 31 ), the parallel-motion control (step S 3 ) ends without executing process of step S 32  and thereafter, in other words, skipping the processes to parallel-move the vehicle  1  to a desired direction. 
         [0173]    If, for example, the driver mistakenly operates the parallel-motion switch  54  carelessly to move the position thereof from the right to the release while the vehicle  1  is being parallel-moved toward the right, the movement-direction memory  73   a  is not updated from “2” to “1” until the vehicle  1  is parked (see  FIG. 5 ). Therefore, the vehicle  1  can be prevented from stopping abruptly, even if the parallel-motion control (step S 3 ) ends in the above condition (Yes at S 31 ). 
         [0174]    If it is determined that the movement-direction memory  73   a  is not set to “1” (No at step S 31 ), it means that the parallel-motion switch  54  is set either to its left (“0”) or right (“1”) position (see  FIG. 5 ). It is assumed that the operator has just given an instruction to parallel-move the vehicle  1  either to the left or right, or the parallel-motion control has been started and the vehicle  1  is being parallel-moved toward the left or the right. Therefore, when if the movement-direction memory  73   a  is not determined to be set to “1” (No at step S 31 ), the subsequent process of step S 32  and thereafter are executed to start or to continue the parallel-motion control. 
         [0175]    Step S 32  determines if the control in the saving mode is required (step S 32 ). The CPU  71  reads the wheel-spin count of the wheels  2  from the front-left to rear-right wheel-spin count memories  74 FLMe to  74 RRMe, respectively, and compares each of the wheel-spin count to a reference value stored in advance in the ROM  72  to determine if there is any wheel  2  with spin count exceeding the reference value. 
         [0176]    If there is no wheel  2  whose spin count exceeds the reference value, the CPU  71  determines that each of the wheels  2  are used (worn out) uniformly and it is not necessary to perform the parallel-motion control in the saving mode. Therefore, the CPU  71  selects the control in the normal mode (for example, using the pattern shown in  FIG. 3A ). 
         [0177]    If there is at least one wheel  2  with spin count exceeding the reference value, the CPU  71  determines that each wheel  2  is used in different frequency (spun for different times). The CPU  71  then selects a saving mode (for example, using the pattern shown in  FIG. 3B  or  3 C) to prohibit using the wheels  2  that are used at a high frequency so as to avoid further being worn out. 
         [0178]    According to the first embodiment of the present invention, if there is more than one wheel  2  whose spin count exceeds the reference value, the wheel  2  with the highest spin count is prohibited from rotation. For example, if the spin count of the front-right wheel  2 FRW is the highest, the parallel-motion of the vehicle  1  is controlled using the pattern shown in  FIG. 3C  so as to prohibit the rotation of the front-right wheel  2 FRW upon parallel-moving the vehicle  1  in toward the right. If the front-left wheel  2 FLW has the highest spin count, then the parallel-motion of the vehicle  1  is controlled using the pattern shown in  FIG. 3B  so as to prohibit the rotation of the front-left wheel  2 FLW. 
         [0179]    If it is determined that the control in the saving mode is required at step S 32  (Yes at step S 32 ), the CPU  71  reads the control data (the steering condition, the rotation direction and the rotated rate of each wheel  2 ) corresponding to the saving mode (the pattern shown in  FIG. 3B  or  3 C, for example) from the parallel-motion controlling table  72   a  (step S 33 ). If it is determined that the control in the saving mode is not required (No at step S 32 ), the CPU  71  reads the control data corresponding to the normal mode (the pattern shown in  FIG. 3A , for example) from the parallel-motion controlling table  72   a.    
         [0180]    At step S 33  or S 34 , upon reading the control data from the parallel-motion controlling table  72   a , the CPU  71  not only reads the control data corresponding to the mode selected at step S 32 , but also that corresponding to the value maintained in the movement-direction memory  73   a  and is read at step S 31  (that is, the control data corresponding to the direction to parallel-move the vehicle  1 , as specified by the driver). 
         [0181]    After the necessary control data is read from the parallel-motion controlling table  72   a  at step S 33  or S 34 , it is further determined if the wheels  2  have been moved to their parallel-motion positions (in other words, to parallel-move the vehicle  1  toward the right, the wheels  2  are to be moved to one of the positions shown in  FIGS. 3A to 3C ) (step S 35 ). 
         [0182]    If it is determined at step S 35  that the wheels  2  have not been moved to their parallel-motion positions (No at step S 35 ), it could be the first time to perform the parallel-control after the driver has instructed to start thereof. Therefore, the steering information of each wheel  2  (a steered direction, and an absolute value of the steered angle to which the wheel  2  is to be steered to reach its parallel-motion position) is output to the actuator unit  4  (step S 37 ) based on the control data read at step S 33  or S 34 . Subsequently, driving information of the wheels  2  (a rotation direction and a rotation rate) are output to each of the wheel driving units  3 , respectively (step S 38 ). 
         [0183]    The actuator unit  4  steers the wheels  2 , to their parallel-motion positions, respectively, based on the received steering information (for example, see  FIGS. 3A to 3C ). The wheel driving units  3  set the rotation direction and the rotation rate of the wheels  2 , respectively, based on the received driving information to prepare for the gas pedal  53  to be stepped on (see step S 36 ). 
         [0184]    If it is determined at step S 35  that the wheels  2  have already been moved to their parallel-motion position (Yes at step S 35 ), it is considered that the parallel-motion of the vehicle  1  can be started or the vehicle  1  is currently being parallel-moved. Therefore, the operating condition of the gas pedal  53  is detected, and the detected result (operating condition) is output to the wheel driving units  3  (step S 36 ). Subsequently, the parallel-motion control process (step S 3 ) ends. 
         [0185]    As described above, the rotation direction and the rotation rate have been set to the wheel driving unit  3  at step S 38  based on the input control data. When the wheel driving unit  3  receives the operating condition of the gas pedal  53  is at step S 36 , the wheel driving units  3  drive the corresponding wheels  2  in rotation, based on the operating condition of the gas pedal  53  and the rotation direction and the rotation rate set at step S 38 . The vehicle  1  is parallel-moved thereby. 
         [0186]    The CPU  71  detects the rotation speed of the wheels  2  via the wheel-rotation speed sensor units  33 , and controls the wheel driving units  3  with a feed-forward control based on the detected results, so that the wheel driving units  3  drive each wheel  2  at the rotation rate set at step S 38 . 
         [0187]    Referring back to  FIG. 4 , the process executed by the controlling apparatus  10  is further explained. After completion of the parallel-motion control process at step S 3 , a process for storing a wheel-spin count is executed (step S 4 ). The process for storing the wheel-spin count is explained with reference to  FIG. 7 .  FIG. 7  is a flowchart for showing the process for storing the wheel-spin count. 
         [0188]    To store the wheel-spin count (step S 4 ), it is at first determined if the value in the movement-direction memory  73   a  is “1” (step S 41 ). If it is determined the value thereof is not “1” (No at step S 41 ), it is assumed that the parallel-motion switch  54  is at its “left” position (“0”) or “right” position (“2”), that is, the vehicle  1  is in the process of parallel-motion. Therefore, processes at step S 42  and thereafter are executed to detect the spin count of each wheel  2 . 
         [0189]    In other words, if it is determined the value thereof is not “1” (No at S 41 ), a ground speed of the vehicle  1  is detected by the vehicle speed sensor units  32  (step S 42 ), the rotation speed of each wheel  2  is detected by the wheel-rotation speed sensor unit  33  (step S 43 ), and the steered angle of each wheel  2  is detected by the steered-angle sensor unit  31  (step S 44 ). The spin count of each wheel  2  is calculated from the detected ground speed of the vehicle  1 , the rotation speed and the steered angle of each wheel  2  (step S 45 ). Values in the wheel-spin count memories  74 FLMe to  74 RRMe are updated based on the calculated spin count of each wheel  2  (step S 46 ), and the wheel-spin count storing process (step S 4 ) ends. 
         [0190]    If it is determined the value in the movement-direction memory  73   a  is “1” at step S 41  (Yes at step S 41 ), it is assumed that the parallel-motion switch  54  is at the “release” position, the parallel-motion control of the vehicle  1  is not being performed. In other words, it is considered that the vehicle  1  is running normally, or parked. Therefore, if the value in the movement-direction memory  73   a  is “1” (Yes at step S 41 ), it is not necessary to detect the spin count of each wheel  2 . Therefore, step S 42  and thereafter are skipped and the wheel-spin count storing process (step S 4 ) ends. 
         [0191]    According to the first embodiment of the present invention, the spin count of each wheel  2  is detected only when the parallel-motion control of the vehicle  1  is being performed; however, the detection of the wheel-spin count is without limitation, and it is also possible, obviously, to detect the spin count of each wheel  2  when the vehicle  1  is running normally. In other words, step S 41  may also be omitted. 
         [0192]    Referring back to  FIG. 4 , the process executed by the controlling apparatus  10  is further explained. After completing the wheel-spin count storing process at step S 4 , the system control executes other processes (step S 5 ) and returns to step S 2 . The process of step S 2  through step S 5  is repeated while the controlling apparatus  10  is powered on. 
         [0193]    Second through sixth embodiments of the present invention are explained herein with reference to  FIGS. 8A to 8C  and  FIGS. 9A to 9I . Those elements that are the same as in the first embodiment of the present invention are given the same reference numbers, and explanations thereof are omitted herein. 
         [0194]      FIGS. 8A to 8C  are schematic drawings for showing information stored in the parallel-motion controlling table  72   a  according to the second embodiment of the present invention.  FIGS. 8D to 8F  are schematic drawings for showing information stored in the parallel-motion controlling table  72   a  according to the third embodiment of the present invention.  FIGS. 9A to 9C  are schematic drawings for showing information stored in the parallel-motion controlling table  72   a  according to the fourth embodiment of the present invention.  FIGS. 9D to 9F  are schematic drawings for showing information stored in the parallel-motion controlling table  72   a  according to the fifth embodiment of the present invention.  FIGS. 9G to 9I  are schematic drawings for showing information stored in the parallel-motion controlling table  72   a  according to the sixth embodiment of the present invention. 
         [0195]      FIGS. 8A to 8C  and  FIGS. 9A to 9I  show only a part of the information stored in the parallel-motion controlling table  72   a , that is, only patterns for moving the vehicle  1  to the right. In other words, data patterns for moving the vehicle  1  to the left are omitted herein. 
         [0196]    Also, the arrows in  FIGS. 8A to 8C  and  FIGS. 9A to 9I  follow the same conventions defined for the first embodiment of the present invention. Therefore, the explanations thereof are omitted herein. 
         [0197]    According to the second embodiment of the present invention, the right wheels  2 FRW,  2 RRW and the left wheels  2 FLW,  2 RLW are given steering angles of a different absolute value, in contrast to the first embodiment of the present invention, where all of the wheels  2  are steered by the angle of the same absolute value to be arranged at their parallel-motion positions (see  FIGS. 3A to 3C ). 
         [0198]    For example,  FIGS. 8A and 8B  suggest that following information is stored as control data in the parallel-motion controlling table  72   a  according to the second embodiment of the present invention: to steer each of the right wheels  2 FRW,  2 RRW toward the opposing direction; steer the right wheels  2 FRW,  2 RRW by an angle of the same absolute value (steered by 45 degrees in the second embodiment of the present invention); steer the left wheels  2 FLW,  2 RLW by 0 degrees; rotate each of the right wheels  2 FRW,  2 RRW in the opposing direction; rotate the left wheels  2 FLW,  2 RLW in the opposing direction; and rotate each wheels  2  at the same rotation rate (speed). 
         [0199]    When the parallel-motion control is executed, the actuator unit  4  steers the wheels  2  to their respective parallel-motion positions, and the wheel driving unit  3  drives the wheels  2  in rotation to spin each wheel  2  against the road surface based on the pattern described above. 
         [0200]    As a result, the vector component in the forward direction (upward direction in  FIGS. 8A and 8B ) generated by the front wheels  2 FLW,  2 FRW is cancelled out by the vector component in the backward direction (downward direction in  FIGS. 8A and 8B ) generated by the rear wheels  2 RLW,  2 RRW. At the same time, the vector component to the right (right direction in  FIGS. 8A and 8B ) generated by the right wheels  2 FRW,  2 RRW functions as a driving force to drive the vehicle  1  to the right. As a result, the vehicle  1  is parallel-moved to the right (right direction in  FIGS. 8A and 8B ). 
         [0201]      FIG. 8C  suggests that following information is stored as control data in the parallel-motion controlling table  72   a  according to the second embodiment of the present invention: to steer each of the right wheels  2 FRW,  2 RRW toward the opposing directions; steer the right wheels  2 FRW,  2 RRW by an angle of the same absolute value (steered by 45 degrees in the second embodiment of the present invention); steer the left wheels  2 FLW,  2 RLW by 0 degrees; rotate each of the right wheels  2 FRW,  2 RRW in the opposing direction and at the same rotation rate (speed); and prohibit the left wheels  2 FLW,  2 RLW from being rotated. 
         [0202]    When the parallel-motion control takes place using this pattern shown in  FIG. 8C , the vector component in the forward direction (upward direction in  FIG. 8C ) generated by the front-right wheel  2 FRW is cancelled out by the vector component in the backward direction (downward direction in  FIG. 8C ) generated by the rear-right wheel  2 RRW. At the same time, the vector component toward the right (right direction in  FIG. 8C ) generated by the front-right wheel  2 FRW and the vector component toward the right (right direction in  FIG. 8C ) generated by the rear-right wheel  2 RRW together function as a driving force to drive the vehicle  1  to the right. As a result, the vehicle  1  is parallel-moved to the right (right direction in  FIG. 8C ). 
         [0203]    According to the second embodiment of the present invention, the patterns shown in  FIGS. 8A and 8B  correspond to the normal mode, and the pattern shown in  FIG. 8C  corresponds to the saving mode. 
         [0204]    As shown in  FIGS. 8D to 8F , the patterns (information stored in the parallel-motion controlling table  72   a ) according to the third embodiment of the present invention are same as those according to the second embodiment except that the left wheels  2 FLW,  2 RLW are operated instead of the right wheels  2 FRW,  2 RRW. 
         [0205]    When the parallel-motion control takes place using each pattern according to the third embodiment of the present invention, although detailed explanation thereof is omitted herein, the same effects as in those in the first and the second embodiments are achieved; therefore, the vehicle  1  can be moved in parallel. According to the third embodiment of the present invention, the patterns shown in  FIGS. 8D and 8E  correspond to the normal mode, and that shown in  FIG. 8F  corresponds to the saving mode. 
         [0206]    As shown in  FIGS. 9A to 9C , the patterns (information stored in the parallel-motion controlling table  72   a ) according to the fourth embodiment of the present invention are same as those according to the first embodiment (see  FIG. 3A to 3C ) except the each wheel  2  is steered to the opposite direction, and is rotated in the opposite direction. 
         [0207]    When the parallel-motion control takes place using each pattern according to the fourth embodiment of the present invention, although detailed explanation thereof is omitted herein, the same effects as in those in the first to third embodiments are achieved; therefore, the vehicle  1  can be parallel-moved. According to the fourth embodiment of the present invention, the patterns shown in  FIGS. 9A and 9B  correspond to the normal mode, and that shown in  FIG. 9C  corresponds to the saving mode. 
         [0208]    As shown in  FIGS. 9D to 9F , the patterns (information stored in the parallel-motion controlling table  72   a ) according to the fifth embodiment of the present invention are same as those according to the second embodiment (see  FIGS. 8A to 8B ), except the right wheels  2 FRW,  2 RRW are steered to the opposite directions, and all of the wheels  2  are rotated in the opposite directions. 
         [0209]    As shown in  FIGS. 9G to 9I , the patterns (information stored in the parallel-motion controlling table  72   a ) according to the sixth embodiment of the present invention is same as that according to the third embodiment (see  FIGS. 8D to 8F ), except the left wheels  2 FLW,  2 RLW are steered to the opposite directions, and all of the wheels  2  are rotated in the opposite directions. 
         [0210]    When the parallel-motion control takes place using each pattern according to the fifth and sixth embodiments of the present invention, although detailed explanation thereof is omitted herein, the same effects as in those in the first to fourth embodiments are achieved; therefore, the vehicle  1  can be parallel-moved. 
         [0211]    According to the fifth embodiment of the present invention, the patterns shown in  FIGS. 9D and 9E  correspond to the normal mode, and that show in  FIG. 9F  corresponds to the saving mode. According to the sixth embodiment of the present invention, the patterns shown in  FIGS. 9G and 9H  correspond to the normal mode, and that show in  FIG. 9I  corresponds to the saving mode. 
         [0212]    Seventh and eighth embodiments of the present invention are explained herein with reference to  FIGS. 10A and 10B . These elements that are the same as the above embodiments of the present invention are given the same reference numbers, and explanations thereof are omitted herein.  FIGS. 10A and 10B  are schematic drawings for showing information stored in the parallel-motion controlling table  72   a  according to the seventh and eighth embodiments, respectively, of the present invention. 
         [0213]      FIGS. 10A to 10B  show only part of the information stored in the parallel-motion controlling table  72   a , that is, the patterns for moving the vehicle  1  to the right, and illustration of the patterns for moving the vehicle  1  to the left is omitted herein. Also, the arrows in  FIGS. 10A and 10B  follow the same conventions defined for the first embodiment of the present invention. Therefore, the explanations thereof are omitted herein. 
         [0214]    According to each embodiment explained above utilizes the patterns (information stored in the parallel-motion controlling table) having at least right wheels  2 FRW,  2 RRW steered by an angle of the same absolute value, and left wheels  2 FLW,  2 RLW steered by an angle of the same absolute value (see  FIGS. 3A to 3C ,  FIGS. 8A to 8C , and  FIGS. 9A to 9I ). In the patterns according to the seventh and eight embodiment of the present invention, different absolute values are stored for the right wheels  2 FRW,  2 RRW, and also for the left wheels  2 FLW,  2 RLW. 
         [0215]    For example,  FIG. 10A  suggests that following information is stored as control data in the parallel-motion controlling table  72   a  according to the seventh embodiment of the present invention: to steer the front-right wheel  2 FRW and rear-left wheel  2 RLW toward the opposing direction; steer the front-right wheel  2 FRW and rear-left wheel  2 RLW by an angle of the same absolute value (steered by 45 degrees in the seventh embodiment of the present invention); steer the front-left wheel  2 FLW and rear-right wheel  2 RRW by 0 degrees; rotate the front wheels  2 FLW,  2 FRW to forward; rotate the rear wheels  2 RLW,  2 RRW to reverse; rotate the front-right wheel  2 FRW and rear-left wheel  2 RLW at the same rotation rate (speed); rotate the front-left wheel  2 FLW and rear-right wheel  2 RRW at the same rotation rate (speed); and rotate the front-right wheel  2 FRW and rear-left wheel  2 RLW at the speed lower (or higher) than the front-left wheel  2 FLW and rear-right wheel  2 RRW. 
         [0216]    When the parallel-motion control is executed, the actuator unit  4  steers the wheels  2  to their respective parallel-motion positions, and the wheel driving unit  3  drives the wheels  2  in rotation to spin each wheel  2  against the road surface based on the pattern described above. 
         [0217]    As a result, the vector component in the forward direction (upward direction in  FIG. 10A ) generated by the front-left wheel  2 FLW is cancelled out by the vector component in the backward direction (downward direction in  FIG. 10A ) generated by the rear-right wheel  2 RRW. At the same time, the vector component in the forward direction (upward direction in  FIG. 10A ) generated by the front-right wheel  2 FRW is cancelled out by the vector component in the backward direction (downward direction in  FIG. 10A ) generated by the rear-left wheel  2 RLW. The vector component toward the right (right direction in  FIG. 10A ) generated by the front-right and rear-left wheels  2 FRW,  2 RLW function as a driving force to drive the vehicle  1  to the right. As a result, the vehicle  1  is parallel-moved to the right (right direction in  FIG. 10A ). 
         [0218]      FIG. 10B  suggests that following information is stored in the parallel-motion controlling table  72   a  according to the eighth embodiment of the present invention as control data: steer the front-left wheel  2 FLW and rear-right wheel  2 RRW toward the opposing direction; steer the front-left wheel  2 FLW and rear-right wheel  2 RRW by an angle of the same absolute value (steered by 45 degrees in the seventh embodiment of the present invention); steer the front-right wheel  2 FRW and the rear-left wheel  2 RLW by 0 degrees; rotate the right wheels  2 FRW,  2 RRW to forward; rotate the left wheels  2 FLW,  2 RLW to reverse; rotate the front-right wheel  2 FRW and rear-left wheel  2 RLW at the same rotation rate (speed); rotate the front-left wheel  2 FLW and the rear-right wheel  2 RRW at the same rotation rate (speed); and rotate the front-right wheel  2 FRW and the rear-left wheel  2 RLW at a speed higher (or lower) than the front-left wheel  2 FLW and the rear-right wheel  2 RRW. 
         [0219]    When the parallel-motion control takes place using the pattern according to the eighth embodiment of the present invention, although detailed explanation thereof is omitted herein, the same effects as in that in the seventh embodiment are achieved; therefore, the vehicle  1  can be parallel-moved. 
         [0220]    A ninth embodiment of the present invention is explained herein with reference to  FIGS. 11A to 11D . These elements that are the same as the above embodiments of the present invention are given the same reference numbers, and explanations thereof are omitted herein.  FIGS. 11A and 11B  are schematic diagram for explaining the ninth embodiment of the present invention.  FIGS. 11C and 11D  are schematic drawings for showing information stored in the parallel-motion controlling table  72   a  according to the ninth embodiment of the present invention. 
         [0221]      FIGS. 11C and 11D  show only part of the information stored in the parallel-motion controlling table  72   a , that is, the patterns for moving the vehicle  1  to the right, and illustration of the patterns for moving the vehicle  1  to the left is omitted herein. Also, the arrows in  FIGS. 11C and 11D  follow the same conventions defined for the first embodiment of the present invention. Therefore, the explanations thereof are omitted herein. 
         [0222]    When the parallel-motion control takes place using the pattern shown in  FIG. 11A , the front wheels  2 FLW,  2 FRW generate the force to move the vehicle  1  to the right. Therefore, the entire vehicle  1  is pushed to the right, with the front side thereof (that is, the vehicle side having the front wheels  2 FLW,  2 FRW) tilted. As a result, the entire vehicle  1  is moved to the right with clockwise rotation as shown in  FIG. 11B . 
         [0223]    In response to the above, according to the ninth embodiment of the present invention, the wheel driving units  3  are driven so as to cancel the rotating force caused by the lateral component of the driving force generated by the front wheels  2 FLW to  2 RRW, which attempts to rotate the entire vehicle  1 , by the longitudinal component generated by the same wheels. 
         [0224]    More specifically, according to the ninth embodiment of the present invention, the vehicle  1  is prevented from rotation by adopting the pattern shown in  FIGS. 11C and 11D . In other words,  FIG. 11C  suggests that following information is stored as control data in the parallel-motion controlling table  72   a  according to the ninth embodiment of the present invention: to steer each of the front wheels  2 FLW,  2 FRW to the opposing direction (with a tendency of toe-in in the ninth embodiment of the present invention); steer the front wheels  2 FLW,  2 FRW by an angle of the same absolute value (steered by 45 degrees in the ninth embodiment of the present invention); steer the rear wheels  2 RLW,  2 RRW by 0 degrees; rotate the front-left and rear-right wheels  2 FLW,  2 RRW to forward; rotate the front-right and rear-left wheels  2 FRW,  2 RLW to reverse; rotate the front wheels  2 FLW,  2 FRW at the same rotation rate (speed); and rotate the rear-right wheel  2 RRW at a speed higher than the rear-left wheel  2 RLW. 
         [0225]    When the parallel-motion control is executed, the actuator unit  4  steers the wheels  2  to their respective parallel-motion positions, and the wheel driving unit  3  drives the wheels  2  in rotation to spin each wheel  2  against the road surface based on the pattern described above. 
         [0226]    As a result, the component to the right (right direction in  FIG. 11A ), which is generated by the front wheels  2 FLW,  2 FRW, acts on the vehicle  1  to be rotated to the right. Upon canceling the driving force of the front and rear wheels  2 FLW to  2 RRW in the longitudinal direction (upward/downward direction in  FIG. 11A ), there remains a driving force only in the rear-right wheel  2 RRW to the forward direction of the vehicle  1  (upward direction in  FIG. 11A ). This remaining force at the rear-right wheel  2 RRW functions to cancel the force to rotate the vehicle  1  to the right. In this manner, the vehicle  1  is parallel-moved to the right side of the vehicle  1  (right direction in  FIG. 11D ). 
         [0227]    Variations of the ninth embodiment of the present invention are explained herein with reference to  FIGS. 12A to 12I  and  FIGS. 13A to 13I .  FIGS. 12A to 12I  and  FIGS. 13A to 13I  are schematic drawings for showing information stored in the parallel-motion controlling table  72   a , and show variations of the information stored in the parallel-motion controlling table  72   a  according to the ninth embodiment of the present invention. 
         [0228]      FIG. 12A  shows the information stored in the parallel-motion controlling table  72   a  according to the ninth embodiment of the present invention (same as  FIG. 11C ).  FIGS. 12B to 12I  and  FIGS. 13A to 13I  are variation thereof, having different parallel-motion positions (steered angles, rotation direction or rotation rate) of each wheel  2 . 
         [0229]    The elements that are the same as in the above embodiments are given the same reference numbers, and explanations thereof are omitted herein. In  FIGS. 12A to 12I  and  FIGS. 13A to 13I , the reference numbers “ 2 FLW to  2 RRW”, showing the front and rear wheels, are omitted for easier understanding. The arrows in  FIGS. 12A to 12I  and  FIGS. 13A to 13I  follow the same conventions defined for the first embodiment of the present invention. Therefore, the explanations thereof are omitted herein. 
         [0230]    By performing the parallel-motion control according to each pattern shown in  FIGS. 12A to 12I  and  FIGS. 13A to 13I , the same effect as the ninth embodiment are achieved. In other words, when the vector component toward the lateral direction of the vehicle  1 , generated by the wheels  2 FLW to  2 RRW attempts to rotate the entire vehicle  1 , the rotating force thereof is cancelled by the vector components in the longitudinal direction generated by the wheels  2 FLW to  2 RRW. As a result, the vehicle  1  can be parallel-moved. 
         [0231]    A tenth embodiment of the present invention is explained herein with reference to  FIGS. 14A to 14C .  FIGS. 14A to 14C  are schematic drawings for showing information stored in the parallel-motion controlling table  72   a  according to the tenth embodiments of the present invention. The arrows in  FIGS. 14A to 14C  follow the same conventions defined for the first embodiment of the present invention. Therefore, the explanations thereof are omitted herein. 
         [0232]    In the first embodiment of the present invention, the vehicle  1  includes four of the wheels  2  in total, including the front to rear wheels  2 FLW to  2 RRW. On the contrary, a vehicle  1  according to the tenth embodiment includes six wheels in total. The elements that are the same as in the above embodiments of the present invention are given the same reference numbers, and explanations thereof are omitted herein. 
         [0233]    As shown in  FIGS. 14A to 14C , the vehicle  1  according to the tenth embodiment includes six wheels in total. The front-left wheel  2 FLW and the front-right wheel  2 FRW located at the front side of the vehicle  1  with respect to the driving direction; the rear-left wheel  2 RLW and the rear-right wheel  2 RRW located at the rear side of the vehicle  1  with respect to the driving direction; and intermediate wheels  200 CLW and  200 CRW located between the front wheels  2 FLW,  2 FRW and the rear wheels  2 RLW,  2 RRW, respectively. 
         [0234]    The intermediate wheels  200 CLW,  200 CRW are driven in rotation by the wheel driving unit (not shown) in the same manner as for the wheels  2 FLW to  2 RRW, and are supported on the vehicle  1  via lifting/supporting mechanisms, which lift the intermediate wheels  200 CLW,  200 CRW upward and downward with respect to the vehicle  1  (in the vertical direction with respect to the paper surface on which  FIGS. 14A to 14C  are placed). 
         [0235]    In other words, during a normal operation, the intermediate wheels  200 CLW,  200 CRW are lifted down by the lifting/supporting mechanisms so as to contact the road surface, and driven in rotation by the wheel driving unit  3 . In this manner, the driving force of the vehicle  1  can be enhanced. For the operation under the parallel-motion control, the intermediate wheels  200 CLW,  200 CRW are lifted from the road surface by the lifting/supporting mechanisms. In this manner, a driving force required for the parallel-motion control and the size of the wheel driving unit  3  (see  FIG. 1 ) can be reduced. The intermediate wheels  200 CLW,  200 CRW is also prevented from wearing out so as to extend the lifetime thereof. 
         [0236]    The parallel-motion control according to the tenth embodiment is the same as that according to the first embodiment (see  FIG. 3 ), except the intermediate wheels  200 CLW,  200 CRW are lifted up and down by the lifting/supporting mechanisms. Therefore, the explanation thereof is omitted herein. 
         [0237]    In the flowchart (the parallel-motion control) shown in  FIG. 6 , the first operating section according to claim  1  corresponds to step S 37 ; the second operating section according to claim  1  corresponds to steps S 36  and S 38 ; the detecting section according to claim  5  correspond to step S 32 ; the determining section according to claim  5  corresponds to step S 32 ; a prohibiting section according to claim  5  corresponds to step S 33 . In the flowchart (the wheel-spin count storing process) shown in  FIG. 7 , the detecting section according to claim  5  corresponds to steps S 42 , S 43 , S 44 , and S 45 . 
         [0238]    The present invention is explained herein with reference to the embodiment thereof; however, these embodiments are not intended to limit a scope of the present invention. It should be obvious for those skilled in the art that various improvements thereof are possible without deviating from the purpose of the present invention. 
         [0239]    For example, the values indicated in the above embodiments are just examples; therefore, other values can also be used, naturally. 
         [0240]    In the first to the ninth embodiment of the present invention, the vehicle  1  has four wheels  2  in total and, in the tenth embodiment, six wheels  2  in total. However, the numbers of wheels  2  are without limitation; therefore, the number of the wheels  2  may be three, five, or more than seven. 
         [0241]    There is a phrase “the steerable wheels comprise a front-right wheel, a front-left wheel, a rear-right wheel, and a rear-left wheel” in claims  3  and  4 . This phrase means that the wheels includes at least four of the wheels  2  (the front to rear wheels  2 FLW to  2 FRW), and is not intended to exclude those having five or more wheels  2 . Therefore, the vehicle  1  having six wheels  2  (the front and rear wheels  2 FLW to  2 FRW, and intermediate wheels  200 CLW,  200 CRW), as described in the tenth embodiment of the present invention, is within the scope of claim  3  or claim  4 . 
         [0242]    According to the above embodiments of the present invention, the vehicle  1  is explained to be parallel-moved to the right; however, obviously, it is possible to move the vehicle  1  to the left based on the same technical concept described with reference to the above embodiments. 
         [0243]    A unit for resetting the spin count memories  74 FLMe to  74 RRMe may be provided to reset (clear to 0) counts in the wheel-spin count memories  74 FLMe to  74 RRMe individually when a wheel  2  is replaced with a new one, although explanation thereof is omitted in the above embodiments. Also, it is also possible to provide a unit to correct (increment or decrement) counts in the wheel-spin count memories  74 FLMe to  74 RRMe. Also in the above embodiments of the present invention, the actuators  4  are implemented as electrical motors, and the articulating mechanisms  23  are implemented as threads; however, implementations thereof are without limitation. For example, the actuators  4  may be implemented as hydraulic or pneumatic cylinder. These implementations would allow the articulating mechanisms  23  to be removed, simplifying the structure, therefore, to reduce the weight and parts cost thereof. 
         [0244]    Also, in the above embodiments of the present invention, explanation about a brake is omitted. However, it is obviously possible to provide a brake (such as a drum brake or a disk brake utilizing a frictional force) to some or all of the wheels  2 . Furthermore, the wheel driving unit  3  may also function as a regenerative brake in replacement of, or in addition to such a brake. 
         [0245]    Furthermore, in the explanation of the above embodiments, the vehicle  1  is moved in the lateral direction (for example, the right and left directions in  FIG. 1 ). However, the parallel-motion control of the present invention is not limited to the lateral movement, and it is also obviously possible to parallel-move the vehicle  1  to other directions (such as the diagonal direction toward the front-right of the vehicle  1 ). 
         [0246]    In other words, the parallel-motion control of the present invention is not limited to the movement of the vehicle  1  in the lateral directions, but also can be moved in any other directions. For example, a phrase “the vehicle is controlled to move in a direction toward an angle that is at least larger than the maximum steerable angle of the wheels” in claim  1  has the same intention. Therefore, the moving directions by such a control obviously include all other directions. 
         [0247]    An eleventh embodiment of the present invention is explained herein with reference to  FIGS. 16 to 22 . According to the first to the tenth embodiments of the present invention, the controlling apparatus  10  of the vehicle  1  controls the steering and the rotation of the wheels  2 , upon performing the parallel-motion control, by operating the wheel driving unit  3  and the actuator unit  4 . Instead, a controlling apparatus  10  of the vehicle  1  according to the eleventh embodiment of the present invention, rotation of the vehicle  1  is controlled by the actuator unit  4  and the wheel driving unit  3  operating on the basis of a surrounding environment to control the steering and the rotation of the wheels  2 . 
         [0248]      FIG. 16  is a schematic drawing for showing a vehicle  1  provided with a controlling apparatus  100  according to the eleventh embodiment of the present invention. The arrow FWD in  FIG. 16  indicates a forward direction of the vehicle  1 . In  FIG. 16 , each wheel  2  is shown steered by a given angle. 
         [0249]    To begin with, a general structure of the vehicle  1  is explained herein. As shown in  FIG. 16 , the vehicle  1  includes a body frame BF, a plurality of wheels  2  (four wheels in the eleventh embodiment of the present invention) supported by the body frame BF, a wheel driving unit  3  that drives each wheel  2  in rotation independently, and an actuator unit  4  that operates to steer each wheel  2  independently. 
         [0250]    Each components included in the vehicle  1  is described in details. As shown in  FIG. 16 , the wheels  2  include four wheels: the front-left wheel  2 FLW and the front-right wheel  2 FRW located at the front side of the vehicle  1  with respect to the driving direction, and the rear-left wheel  2 RLW and the rear-right wheel  2 RRW located at the rear side of the vehicle  1  with respect to the driving direction. These wheels  2 FlW to  2 RRW can be steered by steering units  20 ,  30 . 
         [0251]    The steering units  20 ,  30  are provided to steer each of the wheels  2 , and mainly include kingpins  21 , tie rods  22 , and articulating mechanisms  23 , respectively, as shown in  FIG. 16 . Each of the kingpins  21  supports each wheel  2  allowing a pivoting movement thereof, and each of the tie rod  22  is linked to a knuckle arm (not shown) of each wheel  2 . Each of the articulating mechanisms  23  is provided to articulate a driving force of the actuator  4  to the tie rod  22 , respectively. 
         [0252]    As described above, the actuator unit  4  is a driving/steering mechanism to steer and drive each wheel  2  independently. As shown in  FIG. 16 , the actuator unit  4  includes four actuators,  4 FLA to  4 RRA, at the front-left, front-right, rear-left, and rear-right of the vehicle, respectively. When a driver turns a steering wheel  51 , all or some (for example, only those for front wheels  2 FLW,  2 FRW) of the actuators  4 FLA to  4 RRA are driven to steer the wheels  2  by an angle determined by amount the steering wheel  51  is steered. 
         [0253]    Even when the driver does not turn the steering wheel  51 , the actuators  4 FRA to  4 RLA are driven to steer the wheels  2  to a lateral direction depending on the environment surrounding the vehicle  1 , when a turning control process is triggered. The turning control process, which is to be described in details hereinafter, is triggered when the driver pushes down (turns on) a small-turn switch  46 . The turning control process allows the vehicle  1  to make a small-turn in the environment surrounding thereof. The corresponding actuators  4  (the front-left to the rear-right actuators  4 FLA to  4 RRA) are also driven as required to improve the braking force or the driving force. 
         [0254]    In other words, the actuator unit  4  operates to steer the wheels  2  for two purposes: to turn the vehicle  1 , and to improve the braking force or the driving force. In the eleventh embodiment of the present invention, the former is referred to as a turning control, and the latter is referred to as a steering control. As mentioned above, the turning control process takes place when the driver turns the steering wheel  51 , or pushes down the small-turn switch  46 . Details about the turning control, especially that is triggered by pressing of the small-turn switch  46 , are to be explained hereinafter with reference to  FIGS. 22 and 23 . 
         [0255]    According to the eleventh embodiment of the present invention, the front-left to rear-right actuators  4 FLA to  4 RRA are implemented as electrical motors, and the articulating mechanisms  23  are implemented as screws. When the electrical motor is rotated, the rotating movement thereof is converted into a liner movement by the articulating mechanism  23 , and articulated to the tie rod  22 . As a result, the wheel  2  is driven to pivot around the kingpin  21 , and the wheel  2  is steered by a given angle. 
         [0256]    The wheel driving unit  3  is provided to rotate each wheel  2  independently. As shown in  FIG. 16 , the wheel driving unit  3  includes four electrical motors (front-left to rear-right motors,  3 FLM to  3 RRM, respectively), one for each wheel  2  (that is, as in-wheel motors). When the driver operates a gas pedal  53 , each wheel driving unit  3  applies a driving force to each wheel  2 , and the wheel  2  is rotated at a speed determined by how far the gas pedal  53  was stepped on by the driver. When the driver steps on the gas pedal  53 , the electrical motors (front-left to rear-right motors,  3 FLM to  3 RRM, respectively) are rotated in a forward or a reverse direction, which is selected by a forward-motion switch  42  or a backward-motion switch  44  (selected by the driver pushing the switches). If the forward-motion switch  42  is pressed, the vehicle  1  is moved forward; if the backward-motion switch  44  is pressed, the vehicle  1  is moved backward. 
         [0257]    The controlling apparatus  100  controls each unit in the vehicle  1  having the structure described above. The controlling apparatus  100  controls to operate the wheel driving unit  3  when the gas pedal  53  is operated, and controls actuator unit  4  (performs turning control and steering control thereof) when the steering wheel  51 , the brake pedal  52 , or the gas pedal  53  is operated. The controlling apparatus  100  also performs the turning control and steering control, which is to be explained hereinafter, upon detection thereby of the small-turning switch  46  being pressed (see  FIGS. 22 and 23 ). Details about a structure of the controlling apparatus  100  are described below with reference to  FIG. 17 . 
         [0258]      FIG. 17  is a block diagram for showing an electrical configuration of the controlling apparatus  100 . As shown in  FIG. 17 , the controlling apparatus  100  includes the CPU  71 , the ROM  72 , the RAM  73 , and a hard disk  75  (hereinafter, “HDD  75 ”), each of which is connected to an input-output port  76  via a bus line  75 . A plurality of units, such as the wheel driving unit  3 , is connected to the input-output port  76 . 
         [0259]    The CPU  71  is a processor that controls each unit connected via the bus line  75 . The ROM  72  is a non-writable, nonvolatile memory that stores therein, for example, controlling programs executed by the CPU  71  or fixed value data. The programs for executing the process shown in flowchart of  FIGS. 22 and 23  are stored in the ROM  72 . 
         [0260]    The ROM  72  also stores therein a plurality of turn controlling tables  72   b . The turn controlling tables  72   b  stores vehicle turning patterns, including an x-direction protruding length Ex and a y-direction protruding length Ey corresponding to each axis to turn the vehicle  1 . The turn controlling tables  72   b  include a front-turn controlling table  72   b   1  that stores the vehicle turning patterns used to make a front turn with the vehicle, and a rear-turn controlling table  72   b   2  that stores the vehicle turning patterns used to make a rear turn with the vehicle. Structures of the turn controlling tables  72   b  (the front-turn controlling table  72   b   1  and the rear-turn controlling table  72   b   2 ) are to be explained hereinafter with reference to  FIG. 18 . 
         [0261]    The RAM  73  is a memory that stores various data in a writable fashion while the controlling programs are being executed, and includes a candidate memory  73   b . When it is determined that one of the vehicle turning patterns, stored in the turn controlling tables  72   b , to enable the vehicle  1  to make a turn as a result of a turning control process (see  FIG. 22 ) to be explained hereinafter on the basis of the surrounding environment, the vehicle turning pattern is temporarily stored in the candidate memory  73  as a candidate. The candidate memory  73   b  is initialized (cleared) when the turning control process starts (see  FIG. 22 ). 
         [0262]    The HDD  75  is a writable, nonvolatile memory having a large storage capacity, and stores a map database  75   a  (hereinafter, “map DB  75   a ”) and a parking lot database  75   b  (hereinafter, “parking lot DB  75   b ”). 
         [0263]    The map DB  75   a  is provided to accumulate map data. For example, the map data are read from a medium recorded with map data (such as a DVD) using a data reading apparatus (for example, a DVD apparatus) not shown, or received from an external information center via a communicating apparatus not shown as well. 
         [0264]    The parking lot DB  75   b  is provided to accumulate parking lot data. The parking lot DB  75   b  stores data such as a shape of an entire parking lot, positions of the boundaries of parking space, a size thereof, or a width of an attached driveway. 
         [0265]    As described above, the wheel controlling units  3  drives each wheel  2  (see  FIG. 16 ) in a rotating motion, respectively, and includes four motors  3 FLM to  3 RRM at front-right, front-left, rear-right, and rear-left, and a driving circuit (not shown) that controls to drive each of the motors  3 FLM to  3 RRM based on an instruction from the CPU  71 . 
         [0266]    As also described above, the actuator unit  4  steers each wheel  2 , and include four actuators  4 FLA to  4 RRA for each wheel, and a driving circuit (not shown) that controls to drive each of the actuators  4 FLA to  4 RRA based on instructions from CPU  71 . 
         [0267]    A steered-angle sensor unit  31  is provided to detect a steered angle of each wheel  2 , and to output the detected result to the CPU  71 . The steered-angle sensor unit  31  includes four steered-angle sensors  31 FLS to  31 RRS for each wheel  2 , and a processing circuit (not shown) for processing detection results of the steered-angle sensors  31 FLS to  31 RRS and outputting processed results to the CPU  71 . 
         [0268]    The steered-angle, detected by the steered-angle sensor unit  31 , is an angle enclosed by a center line laid across the diameter of the wheel  2  and a reference line laid on a side of the vehicle  1  (the body frame BF) (both lines not shown), and determined regardless of the direction in which the vehicle  1  moves to. 
         [0269]    The vehicle speed sensor unit  32  is provided to detect the ground speed (absolute value and moving direction) of the vehicle  1  with respect to a road surface and to output the detected results to the CPU  71 . The vehicle speed sensor unit  32  includes a longitudinal acceleration sensor  32   a , a lateral acceleration sensor  32   b , and a processing circuit (not shown) that process the results detected by each acceleration sensor  32   a ,  32   b  and outputs the processed results to the CPU  71 . 
         [0270]    The longitudinal acceleration sensor  32   a  detects accelerated velocity of the vehicle  1  (the body frame BF) in the forward and backward directions (upward and downward directions in  FIG. 16 ). The lateral acceleration sensor  32   a  detects accelerated velocity of the vehicle  1  (the body frame BF) in the right and left directions (right and left directions in  FIG. 16 ). The CPU  71  can calculate a ground speed (an absolute value and a moving direction) of the vehicle  1  by obtaining time integration (acceleration value) of each result detected by acceleration sensors  32   a ,  32   b , respectively, to obtain the velocity in each direction (longitudinal and lateral directions), and combining these two vector components. 
         [0271]    The wheel-rotation speed sensor unit  33  is provided to detect a rotation speed of the wheels  2 , respectively, and to output the detected results to the CPU  71 . The wheel-rotation speed sensor unit  33  includes four rotation speed sensors  33 FLS to  33 RRS for each wheel  2 , and a processing circuit (not shown) that process the results detected by each rotation speed sensor  33 FLS to  33 RRS and outputs the processed results to the CPU  71 . The CPU  71  can calculate actual circumferential velocity of each wheel  2  from the rotation speed of each wheel  2  received from the wheel-rotation speed sensor units  33 , and external diameters of each wheel  2  stored in the ROM  72  in advance. 
         [0272]    A steering-wheel steered-angle detecting sensor  36  detects a steered angle of the steering wheel  51 . The steered angle of the steering wheel  51  can be obtained by inputting the detection result of the steering-wheel steered-angle detecting sensor  36  to the CPU  71 . 
         [0273]    The forward-motion switch  42  is pressed by the driver when he/she desires to move the vehicle  1  to forward. When the forward-motion switch  42  is pressed (turned on), the wheel driving units  3 FLM to  3 RRM, respectively located at the front-right, front-left, rear-right, and rear-left of the vehicle  1 , are driven to forward. As a result, the vehicle  1  moves forward. 
         [0274]    The backward-motion switch  44  is pressed by the driver when he/she desires to move the vehicle  1  to reverse. When the forward-motion switch  44  is pressed (turned on), the wheel driving units  3 FRM to  3 RLM, respectively located at the front-right, front-left, rear-right, and rear-left of the vehicle  1 , are driven to reverse. As a result, the vehicle  1  moves backward. While the forward switch  42  is pressed (turned on), the backward switch  44  is always off. While the backward switch  44  is pressed (turned on), the forward switch  42  is always off. Both switches cannot be turned on simultaneously. 
         [0275]    The small-turn switch  46  is pressed by the driver when he/she desires to activate the turning control (see  FIG. 22 ), which is to be described hereinafter, to give the controlling apparatus  100  with an instruction to execute the turning control (see  FIG. 22 ). The small-turn switch  46  turns off automatically when the turning control process (see  FIG. 22 ) ends. 
         [0276]    An in-vehicle camera  48  is a small CCD camera that can capture the image of an environment surrounding the vehicle  1 . According to the eleventh embodiment of the present invention, the vehicle  1  is provided with four of the in-vehicle cameras  48 , each located at the front, rear, right and left thereof to capture the image of the environment surrounding the vehicle  1  for 360 degrees. An LCD  50  is a liquid crystal display that displays various information or maps based on the map data. 
         [0277]    A GPS receiver  52  receives position information (for example, latitude and longitude) of the vehicle  1  from a GPS satellite  400 , not shown, via an antenna  52   a . When position information is received from the GPS receiver  52 , the CPU  71  calculates the current position of the vehicle  1  from the received position information, the ground speed detected by the vehicle speed sensor unit  32 , and angular velocity of the vehicle  1  detected by a gyroscope, not shown. 
         [0278]    The above-mentioned turn controlling tables  72   b  are explained herein with reference to  FIG. 18 .  FIG. 18  is a schematic diagram for showing a structure of the turn controlling tables  72   b . As shown in  FIG. 18 , the turn controlling tables  72   b  include the forward-turn controlling table  72   b   1  and the backward-turn controlling table  72   b   2 . 
         [0279]    The front-turn controlling table  72   b   1  stores data patterns to make a front turn with the vehicle  1 , and further includes a front-left turn controlling table  72   b   11  and a front-right turn controlling table  72   b   12 . The front-left turn controlling table  72   b   11  is used to make a front-left turn with the vehicle  1 . The front-right turn controlling table  72   b   12  is used to make a front-right turn with the vehicle  1 . 
         [0280]    The rear-turn controlling table  72   b   2  stores patterns to make a rear turn with the vehicle  1 , and further includes a rear-left turn controlling table  72   b   21  and a rear-right turn controlling table  72   b   22 . The rear-left turn controlling table  72   b   21  is used to make a rear-left turn with the vehicle  1 . The rear-right turn controlling table  72   b   22  is used to make a rear-right turn with the vehicle  1 . 
         [0281]    The front-left turn controlling table  72   b   11 , the front-right turn controlling table  72   b   12 , the rear-left turn controlling table  72   b   21 , the rear-right turn controlling table  72   b   22  respectively store a x-direction protruding length Ex and a y-direction protruding length Ey of typical twenty axes to turn the vehicle  1 , out of an infinite number of turning axes, as patterns to turn the vehicle  1 . The x-direction protruding length Ex and the y-direction protruding length Ey are to be defined hereinafter with reference to  FIG. 20 . 
         [0282]    The front-left turn controlling table  72   b   11 , the front-right turn controlling table  72   b   12 , the rear-left turn controlling table  72   b   21 , the rear-right turn controlling table  72   b   22  are selected depending on values of the initial address specified upon reading the turn controlling tables  72   b . Specifically, parameters M 1  and M 2  are set with values depending on the direction to turn (front-right turn, front-left turn, rear-right turn, rear-left turn) the vehicle  1  in the turning control process (see  FIG. 22 ), which is to be explained hereinafter. As a result, the initial address for reading the turn controlling tables  72   b  is determined. For example, it is determined that the parameter M 1  is set to “R” and the parameter M 2  is set to “F” in the turning control process (see  FIG. 22 ), the front-right turn controlling table  72   b   12  is selected. 
         [0283]    The turning axes recorded in the turn controlling table  72   b  is explained herein with reference to  FIG. 19 .  FIG. 19  is a schematic drawing for explaining twenty representative turning axes selected for a front-left turn according to the eleventh embodiment of the present invention. 
         [0284]    As shown in  FIG. 19 , three turning axes (No.  2 FL to  4 FL) are positioned on a line A connecting a center of a rectangle inscribing the vehicle  1  and a rear-left corner of the vehicle  1 . Another three turning axes (No.  5 FL to  7 FL) are positioned on a line B connecting the center of the vehicle  1  and the front end of the rear-left wheel  2 RL in the vehicle  1 . Still another three turning axes (No.  8 FL to  10 FL) are positioned on a line C connecting the midpoints of two longer sides constituting the rectangle inscribing the vehicle  1 . Still another three turning axes (No.  12 FL to  14 FL) are positioned on a line D connecting the center of the rectangle inscribing the vehicle  1  and a front-left corner of the vehicle  1 . Still another seven turning axes (No.  1 FL,  15 FL to  20 FL) are positioned on a line E connecting the midpoints of the two short sides of the rectangle inscribing the vehicle  1 . A turning axis No.  1 FL is positioned at the center of the rectangle inscribing the vehicle  1  (at the center of the vehicle  1 ). Another turning axis No.  11 FL is positioned at a given point on a rotation axis F connecting the two rear wheels  2 RR,  2 RL of the vehicle  1 , when these wheels are positioned in parallel, and have the same height. 
         [0285]    The turning axes with No.  2 FL,  5 FL,  8 FL,  12 FL,  15 FL, and  18 FL are positioned at intersections between left-side circumference of a circle Ra and the lines A to E, respectively, where the radius of the circle Ra equals to the distance from the center of the vehicle  1  to a width of the vehicle  1 . The turning axes with No.  3 FL,  6 FL,  9 FL,  13 FL,  16 FL, and  19 FL are positioned at intersections between left-side circumference of a circle Rb and the lines A to E, respectively, where the radius of the circle Rb is the diagonal distance from the center of the vehicle  1  to a corner of the rectangle inscribing the vehicle  1 . The turning axes with No.  4 FL,  7 FL,  10 FL,  14 FL,  17 FL, and  20 FL are concentric to the circles Ra and Rb, and are positioned at intersections between left-side circumference of a circle Rc and the lines A to E, respectively, where the diameter of the circle Rc is greater than that of the circle Rb (for example, 1.5 times the diameter of the circle Ra). 
         [0286]    By positioning the twenty turning axes around the vehicle  1  in the manner described above, vehicle turning patterns having twenty types of characteristics can be obtained. According to the eleventh embodiment of the present invention, the vehicle turning patterns are characterized by the x-direction protruding length Ex and the y-direction protruding length Ey. 
         [0287]    The x-direction protruding length Ex and the y-direction protruding length Ey are herein explained with reference to  FIG. 20 .  FIG. 20  is a schematic diagram for explaining the protruding length Ex and the protruding length Ey. 
         [0288]    In  FIG. 20 , the vehicle  1  (4,795 millimeters in length×1,790 millimeters in width×1,770 millimeters in height) makes a turn from a parking space  110  (2.3 meters in width×5.0 meters in length) to a driveway  120  (5.5 meters in width) that is perpendicular to the parking space  110  around the turning axis No.  1 FL. 
         [0289]    The x-direction protruding length Ex is defined as a maximum distance that the vehicle  1  protrudes from a reference line  112  of x-direction upon making a turn. The x-direction reference line  112  is laid in parallel to the side of vehicle  1 , parked at the initial position, being positioned opposite side to the turning direction. (According to the eleventh embodiment of the present invention, the x-direction reference line  112  is laid on a line extending over a longer side of the parking space  110 .) 
         [0290]    The y-direction protruding length Ey is defined as a maximum distance that the vehicle  1  protrudes from a reference line  114  in y-direction laid perpendicularly to the x-direction reference line  112 . The turning axes are searched, in the turning control process (see  FIG. 22 ) described later, by moving the y-direction reference line  114  toward the direction where the vehicle  1  is to move (forward or backward), from the front end of the vehicle  1  at the initial parked position. 
         [0291]    Upon making a front-left turn, for example, the maximum x-direction protruding length Ex corresponds to the path swept by the rear-right corner of the vehicle  1 , and the maximum y-direction protruding length Ey correspond to the path swept by the front-right corner of the vehicle  1 . Assuming that turning axis is at a coordinates (X, Y); the length overall of the vehicle  1  is Lv; and the width overall of the vehicle  1  is Wv, then the distance DISTrr between the turning axis (X, Y) and the rear-right corner of the vehicle  1  can be obtained from an equation: 
         [0000]      DISTrr=SQRT[({Wv/2 }−X ) 2 +({Lv/2 }+Y ) 2 ] 
         [0000]    The distance DISTrf between the turning axis (X, Y) and the front-right corner of the vehicle  1  can be obtained from an equation: 
         [0000]      DISTrf=SQRT[({Wv/2 }+X ) 2 +({Lv/2 }+Y ) 2 ] 
         [0292]    The x-coordinate XrrN of the rear-right corner of the vehicle  1 , upon making a left turn with an angle of N°, can be obtained from the equation: 
         [0000]      XrrN=DISTrr×cos (θ+ N °)− X =DISTrr(cos θ cos  N °−sin θ sin  N °)− X    
         [0000]    where, cos θ=({Wv/2}−X)/DISTrr, and sin θ=({Lv/2}−Y)/DISTrr. 
         [0293]    In the similar manner, the y-coordinate YrfN of the front-right corner of the vehicle  1 , upon making a left turn by an angle of N°, can be obtained from the equation: 
         [0000]      YrfN=DISTrf×sin (θ+ N °)− Y =DISTrf(sin θ cos  N °−cos θ sin  N °)− Y    
         [0000]    where, cos θ=({Wv/2}−X)/DISTrf, and sin θ=({Lv/2}-Y)/DISTrf. 
         [0294]    The x-direction protruding length Ex upon making a left turn by an angle between 0° to N° will be the maximum value between XrrN(0°) and XrrN(N°). The y-direction protruding length Ey will be the maximum value between YrfN(0) and YrfN(N°). 
         [0295]    Therefore, if the width of the area (e.g. a parking lot) to make a turn is Wp, then: 
         [0000]        Ex =(Max {XrrN}−{Wp/2}) [ Ex &gt;0 ], Ex= 0 [Ex&lt; 0]; and 
         [0000]        Ey =(Max {YrfN}+ Y ) [ Ey &gt;0 ], Ey= 0 [Ey&lt; 0]. 
         [0000]    By comparing an acceptable area (movable area), which varies depending on the space to make a turn, with the x-direction protruding length Ex and the y-direction protruding length Ey, the turning axis (X, Y) can be selected. 
         [0296]    It is explained herein with reference to  FIG. 21  the characteristics (that is, the x-direction protruding length Ex and the y-direction protruding length Ey) of each vehicle-turning pattern having one of the twenty axes with No.  1 FL to  20 FL selected for the vehicle  1  for making a front-right turn.  FIG. 21  is a bar graph for showing the values (the x-direction protruding length Ex and the y-direction protruding length Ey) in the vehicle turning patterns, each corresponding each of the twenty turning axes with No.  1 FL to  20 FL, stored in the front-left turn controlling table  72   b   11 . In the bar graph of  FIG. 21 , the turning axes with No.  1 FL to  20 FL are plotted in the horizontal axis, and values of the rotation patterns (the x-direction protruding length Ex and the y-direction protruding length Ey) are plotted in the vertical axis. According to the eleventh embodiment of the present invention, the front and rear overhangs of the vehicle  1  are to be equal. If the front and rear overhangs of the vehicle  1  are different, the turning axis can be changed so as to make these overhangs to be the same by giving a different steering angle, respectively. 
         [0297]    As shown in  FIG. 21 , each turning axis has a characterizing vehicle-turning pattern (that is, the corresponding x-direction protruding length Ex and the y-direction protruding length Ey). For example, there is almost no x-direction protruding length Ex for the turning axes No.  3 FL,  4 FL,  7 FL,  19 FL,  20 FL, meaning that the vehicle  1  can make a turn even if the right side thereof is in contact with a wall. The y-direction protruding length Ey for the turning axis No.  7 FL is smaller than that for the turning axis No.  20 FL. This means that, if space is limited in the moving direction (y-direction) of the vehicle  1 , the turning axis No.  7 FL should be used instead of the turning axis No.  20 FL. The x-direction protruding length Ex for the turning axis No.  17 FL is larger than the y-direction protruding length Ey thereof. This means that the turning axis No.  17 FL is effective for making a turn when there is more space available in the direction (x-direction) perpendicular to the moving direction (y-direction) of the vehicle  1 . 
         [0298]    The turning control of the vehicle  1  according to the eleventh embodiment of the present invention is explained herein with reference to the flowcharts of  FIG. 22  and  FIG. 23 .  FIG. 22  is a flowchart for showing a turning control process executed by the CPU  71  in the vehicle  1 . 
         [0299]    The turning control is triggered by the operator pressing (turning on) the small-turn switch  46  and steering the steering wheel  51  to a desired turning direction (right turn or left turn) (by the steering-wheel steered-angle detecting sensor  36  detecting the rotation of the steering wheel  51 ). To begin with, it is determined if the vehicle  1  is parked (step S 701 ). 
         [0300]    If it is determined that the vehicle  1  is parked at step S 701  (Yes at step S 701 ), an environment recognizing process is executed (step S 702 ). In the environment recognizing process, a movable area map is created. The movable area map shows an area where the vehicle  1  can be moved to, based on recognitions of the surrounding environment of the vehicle  1 . 
         [0301]    A process for recognizing the surrounding environment (step S 702 ) is explained herein with reference to  FIG. 23 . As shown in  FIG. 23 , at the beginning of the environment recognizing process (step S 702 ), current position information of the vehicle  1  is obtained from the position information (latitude and longitude) received from the GPS satellite  400  (not shown) using the GPS receiver  52  (step S 801 ). 
         [0302]    After completion of step S 801 , information about the shape of the area (shape of the premise) around the current position of the vehicle  1  is obtained from the map data stored in the map DB  75   a  and the parking lot data stored in the parking lot DB  75   b  (step S 802 ). 
         [0303]    At step S 802 , because the exact current position of the vehicle  1  is known from step S 801 , it is possible to obtain the information about the exact shape of the area surrounding the current position of the vehicle  1  from the data stored in the map DB  75   a  or the parking lot DB  75   b . The movable area map is created based on the shape of the premise around the current position of the vehicle  1  in the manner to be explained hereinafter. Therefore, by obtaining exact information about the shape of the premise around the current position of the vehicle  1 , the movable area map can be created accurately. As a result, a turning axis of the vehicle  1  can be accurately searched and selected to prevent the vehicle  1  from protruding from the movable area map. In this manner, the vehicle  1  is turned safely without causing a scrape or a collision. 
         [0304]    Subsequently, information about the obstacles around the current position of vehicle  1  is obtained (step S 802 ). The obstacle information can be obtained from the images captured by the in-vehicle cameras  48 , the building or wall information included in the map data stored in the map DB  75   a , and information about the parking space boundaries stored in the parking lot DB  75   b.    
         [0305]    If the obstacle information is obtained via the image captured by the in-vehicle cameras  48 , it is possible to include information not detected by an object-detecting apparatus, such as a sensor or radar (such as a boundary line of the parking space or a center line). 
         [0306]    Therefore, when the vehicle  1  is parked in the parking space  110  (see  FIG. 26B ), the adjacent parking space can be recognized as an obstacle. If the vehicle  1  is to make a turn to drive onto the roadway  160  (see  FIG. 28B ), the center line  180  can be recognized as an obstacle. As to be explained hereinafter, in the turning control process ( FIG. 22 ), a turning axis is selected to avoid the obstacles. Therefore, by recognizing the adjacent parking space or the center line  180  as an obstacle, the vehicle  1  can make a turn safely without causing a scrape or a collision. 
         [0307]    After step S 803 , it is determined if there is a road in the area surrounding the current position of the vehicle  1  (step S 804 ). If there is a road (Yes at step S 804 ), information about the road width (the entire width of the road, and the width of a one-way lane) is obtained by referring to the map data stored in the map DB  75   a  (step S 805 ), and the system control proceeds to step S 806 . If there is no road (No at step S 804 ), step  805  is skipped, and the system control proceeds to step S 806 . 
         [0308]    At step S 806 , the movable area map is created. Upon completion of step S 806 , the environment recognizing process (step S 702 ) ends. 
         [0309]    At step S 806 , the movable area map is created from the premise shape information obtained at step S 802 , the obstacle information obtained at step S 803 , and the road width information obtained at step S 805 , when applicable. The map (movable area map) is basically created by excluding the obstacles indicated by the obstacle information from the area of the premise surrounding the current position of the vehicle  1 . When there is a road around the current position of the vehicle  1 , the lanes legally prohibited to drive (in Japan, right lanes in the driving direction with respect to the center line) are excluded from the area allowed to drive (movable area). 
         [0310]    Explanation continues referring back to  FIG. 22 . After completion of step S 702 , it is determined if the driver has turned the steering wheel  51  to the left (step S 703 ). If it is left (Yes at step S 703 ), the parameter M 1  is set with the value “L” and the system control proceeds to step S 705 . 
         [0311]    At step S 703 , it is determined that the driver has turned the steering wheel  51  to the right (No (right) at step S 703 ), the parameter M 1  is set with “R” (step S 718 ), and the system control proceeds to step S 705 . 
         [0312]    At step S 705 , it is determined if the turn can be made with a normal two-wheel drive, that is, by the driver operating the steering wheel  51  and the gas pedal  53 , on the movable area map obtained at the environment recognizing process (step S 702 ). In other words, at step S 705 , it is determined if the vehicle  1  can make a turn by turning the steering wheel  51  on the movable area map. 
         [0313]    If it is determined at step S 705  that a turn by the normal two-wheel drive is not possible (No at step S 705 ), it is further determined if the driving direction is to the front (forward), in other words, the forward switch  42  is pressed (turned on) (step S 706 ). 
         [0314]    If it is determined that the driving direction is forward (Yes at S 706  (forward)), the parameter M 2  is set with the value “F” (step S 707 ), and the parameter Y is set with “0” (step S 708 ). 
         [0315]    If it is determined that the driving direction is backward (No at S 706  (backward)), in other words, the backward switch  44  is pressed (turned on), the parameter M 2  is set with the value “B” (step S 720 ), and the system control proceeds to step S 708 . 
         [0316]    After completing step S 708 , 4 bytes of data, indicating the x-direction protruding length Ex and the y-direction protruding length Ey, are read from an address obtained by adding a value Y×4 to the initial address pointed by the values of the parameters M 1  and M 2  (step S 709 ). In other words, the x-direction protruding length Ex and the y-direction protruding length Ey corresponding to the driving direction and turning direction are read from the turn controlling tables  72   b  ( 72   b   11 ,  72   b   12 ,  72   b   21 ,  72   b   22 ). For example, it is assumed herein that the value in the parameter M 1  is “L”, the value in the parameter M 2  is “F” and that the parameter Y is “0”. These values points to the initial address of the front-left turn controlling table  72   b   11 . Because the turning axis No.  1 FL is recorded at this address, the x-direction protruding length Ex and the y-direction protruding length Ey corresponding to the turning axis No.  1 FL are read. If it is assumed the value in the parameter M 1  is “L”, the value in the parameter M 2  is “F”, and the parameter Y is “1”, then these values points to the turning axis No.  2 FL in the front-left turn controlling table  72   b   11 . Therefore, the x-direction protruding length Ex and the y-direction protruding length Ey corresponding to the turning axis No.  2 FL are read. 
         [0317]    After completing step S 709 , the read x-direction protruding length Ex and the y-direction protruding length Ey are checked against the movable area map obtained at the environment recognizing process (step S 702 ) to inspect if the vehicle  1  can make a turn (step S 710 ) with the selected turning axis. At step S 710 , the inspection thereof is made by virtually moving the vehicle  1  in the driving direction from the current position to the position to start making a turn. The position to start making a turn may be defined by latitude and longitude calculated from the latitude and longitude of the current position the vehicle  1  obtained by the GPS, or may also be a position obtained relatively by calculation using the images captured by the in-vehicle cameras  48 . 
         [0318]    After completing step S 710 , it is determined if the vehicle  1  can make a turn with the inspected turning axis at step S 711  (step S 711 ). If yes, (Yes at step S 711 ), the turning axis number thereof and the information about the position to start making the turn, which is obtained in the inspection, is stored in the candidate memory  73   b  (step S 712 ), and it is determined if the value of the parameter Y is “19” (step S 713 ). 
         [0319]    If it is determined at step S 711  that the vehicle  1  cannot make a turn with the inspected turning axis (No at step S 711 ), step S 712  is skipped, and the system control proceeds to step S 713 . 
         [0320]    If it is determined at step S 713  that the value in the parameter Y is not “19” (No at step S 713 ), value “1” is added to the parameter Y (S 721 ), and the system control proceeds to step S 709 . If it is determined that the value in the parameter Y is “19” at step S 713  (Yes at step S 713 ), it means that inspections have been done for all of the twenty turning axes recorded in the turn controlling tables  72   b  ( 72   b   11 ,  72   b   12 ,  72   b   21 ,  72   b   22 ), which correspond to the driving direction and turning direction, as to whether it is possible to turn the vehicle  1  therearound. Therefore, it is checked if there is any candidate turning axes stored in the candidate memory  73   b  (step S 714 ). 
         [0321]    If it is determined at step S 714  that there are candidates in the candidate memory  73   b  (Yes at step S 714 ), a turning axis that allows the safest turn is selected from the candidates in the candidate memory  73   b  (step S 715 ). For example, “a turning axis to allow the safest turn” is determined as one that allows a vehicle  1  to turn with a sufficient space, when checked against the movable area map. Or, it could also be a turning axis that enables the vehicle  1  to turn with a most gradual swept path. As a result of step S 715 , the vehicle  1  is turned with a turning axis that is safest to make a turn. In this manner, the vehicle  1  can make a turn safely without causing collision or scraping. 
         [0322]    After completion of step S 715 , the driving control process is executed (step S 716 ), and the turning control process ends. In the driving control process at step S 716 , the vehicle  1  is moved forward or backward to the position to start making a turn with the turning axis selected at step S 715 . Subsequently, the controlling apparatus  100  controls the wheel driving unit  3  and the actuator unit  4  so as to turn the vehicle  1  around the selected turning axis. In the driving control process at step S 716 , it is determined if the vehicle  1  is moved to the starting position by measuring the position using GPS when the starting position is specified by latitude and longitude. Or, it may also be determined based on the images captured by the in-vehicle cameras  48 . 
         [0323]    If it is determined at step S 714  that there is no candidate in the candidate memory  73   b  (No at step S 714 ), a notice is displayed on the LCD  50  to inform the driver that there is no candidate (step S 722 ), and the turning control process ends. The driver can recognize that it is difficult to make a turn from the notice on the display, and make a turn by turning the steering wheel  51  back and forth, or take some other measures. 
         [0324]    If it is determined at step S 701  that the vehicle  1  is not parked (No at step S 701 ), a notice is displayed on the LCD  50  so as to prompt the driver to stop the vehicle  1  (step S 717 ), and the turning control process ends. The driver can stop the vehicle  1  by recognizing the notice on the display, and execute the turning control process again. 
         [0325]    If it is determined at step S 705  that the turn can be made with a normal two-wheel drive (Yes at step S 705 ), a notice is displayed on the LCD  50  to inform the driver that the turn can be made with the two-wheel drive, and the turning control process ends. The driver then can make a turn with the normal two-wheel drive. 
         [0326]    In other words, if it is determined at step S 705  that the turn can be made with a normal two-wheel drive, the normal two-wheel drive (with two-wheel steering) is prioritized. When each wheel  2  is independently steered and rotated, each wheel  2  often slips in rotation. Therefore, the wheels  2  wear out more, when compared with a turn made by a normal two-wheel drive. Therefore, if the environment surrounding the vehicle  1  allows the driver to make a turn by operating the steering wheel  51  and the gas pedal  53 , wear of the wheels  2  can be suppressed by prioritizing the turn by the two-wheel drive. 
         [0327]    As described above, according to the eleventh embodiment of the present invention, an appropriate turning axis (a vehicle turning pattern) is searched so as to allow the vehicle  1  to make a turn in the environment surrounding thereof. Therefore, even when it is difficult for the driver to make a turn by operating the steering wheel  51  and the gas pedal  53  because of the environment surrounding the vehicle  1 , or the area is limited, the controlling apparatus  100  controls the vehicle  1  to steer and rotate each wheel  2  independently so as to make a turn around the searched turning axis. As a result, the vehicle  1  can make an appropriate turn depending on the environment surrounding thereof. Because it does not require the driver to turn the steering wheel  51  back and forth, the vehicle  1  can be turned safely and easily. 
         [0328]    Furthermore, the controlling apparatus  100  controls each wheel  2  to be steered and rotated independently so as to make a turn around an appropriate turning axis. Therefore, each wheel  2  can be steered and rotated without a burden to the driver. As a result, the vehicle  1  can be turned appropriately. 
         [0329]    Furthermore, according to the eleventh embodiment of the present invention, it is determined that there is any turning axis that enables the vehicle  1  to be turned out of the twenty representative turning axes recorded in the turn controlling tables  72   b  in advance. Therefore, an appropriate or most appropriate turning axis can be selected with a small control overhead, allowing a vehicle  1  to be turned using the appropriate or most appropriate vehicle turning pattern. 
         [0330]    It is also possible to allow a driver to select a preferable turning method between a normal two-wheel drive (normal turn with two-wheel steering) and an “ad hoc” turn (a turn made by the driving control process of step S 716 ). 
         [0331]    A twelfth embodiment of the present invention is explained herein with reference to  FIG. 24 . According to the eleventh embodiment described above, all of the twenty turning axes, recorded in the turn controlling tables  72   b  ( 72   b   11 ,  72   b   12 ,  72   b   21 ,  72   b   22 ), are inspected if the vehicle  1  can be turned therearound, and the most appropriate turning axis is selected from the ones that are determined applicable. 
         [0332]    Instead, according to the twelfth embodiment of the present invention, the vehicle  1  is turned around the first turning axis, out of twenty recorded in the turn controlling tables  72   b  ( 72   b   11 ,  72   b   12 ,  72   b   21 ,  72   b   22 ), that is found applicable. The elements that are the same as in the first embodiment of the present invention are given the same reference numbers, and explanations thereof are omitted herein. 
         [0333]      FIG. 24  is a flowchart for showing a turning control process according to the twelfth embodiment of the present invention. As shown in  FIG. 24 , steps S 701  to S 711  are executed in the same manner as in the eleventh embodiment. If it is determined that the vehicle  1  can make a turn with the inspected turning axis at step S 711  (Yes at step S 711 ), the driving control process is executed to move the vehicle  1  to the position to start the vehicle, the position information obtained in the inspection, and to turn the vehicle  1  around the turning axis (step S 716 ). Then, the turning control ends. 
         [0334]    After completion of step S 711 , step S 713  is executed to check if the value in the parameter Y is “19”. If it is “19” (Yes at step S 713 ), a notice is displayed on the LCD  50  so as to inform the driver that there is no turning axis that allows the vehicle  1  to be turned (step S 901 ), and the turning control process ends. 
         [0335]    As explained above, according to the twelfth embodiment of the present invention, when a turning axis is found to allow turning of a vehicle  1  with respect to the surrounding environment, other turning axes are not searched any further, and the controlling apparatus  100  controls the actuator unit  4  and the wheel driving unit  3  so as to turn the vehicle  1  around the selected turning axis. In this manner, not only the control overhead is reduced, but also the turning axis (or the vehicle turning patterns) can be searched faster. As result, the time lag before starting to turn the vehicle  1  is reduced, allowing the vehicle  1  to be turned quickly. 
         [0336]    To execute the turning control process according to the twelfth embodiment of the present invention, the twenty turning axes should be recorded in the turn controlling tables  72   b  ( 72   b   11 ,  72   b   12 ,  72   b   21 ,  72   b   22 ) in advance in the order of favorability, from one with most advantageous conditions to the least advantageous one. In this manner, the first appropriate turning axis found applicable will be the most favorable. For example, the turning axes may be recorded in the turn controlling tables  72   b  ( 72   b   11 ,  72   b   12 ,  72   b   21 ,  72   b   22 ) from one with least worn wheels  2  down to the one with most worn wheel  2 . In this manner, a turn is made using least worn wheels  2 . In this manner, further wear of the wheels  2  can be suppressed. 
         [0337]    The environment information obtaining section mentioned in claim  7  corresponds to the environment recognizing process (step S 702 ), the vehicle turning pattern searching section mentioned therein corresponds to steps S 703  to S 713 , S 718 , S 720 , and S 721 , and the turn controlling section mentioned therein corresponds to the driving control process (step S 716 ). 
         [0338]    The comparing section mentioned in claim  8  corresponds to step S 710 . A driver-operated turnability determining section mentioned in claim  9  corresponds to step S 705 , and the search prohibiting section mentioned therein corresponds to the branched process of Yes at step S 705 . 
         [0339]    The vehicle position obtaining section mentioned in claim  10  corresponds to step S 801 , the premise-shape recognizing section mentioned therein corresponds to step S 802 , the movable area detecting section mentioned therein corresponds to step S 806 . The obstacle information obtaining section mentioned in claim  11  corresponds to step S 803 . 
         [0340]    The present invention is explained herein based on the embodiments thereof. However, the embodiments herein are not intended to limit the scope of the present invention, and it should be obvious for those skilled in art that many variations thereof are possible without deviating from the purpose of the present invention. 
         [0341]    For example, the values mentioned herein are just examples, and it should be obvious that other values may also be used. 
         [0342]    According to the embodiments described above, images captured by the in-vehicle cameras  48 , arranged at the front, rear, right, and left of the vehicle  1 , are used to obtain information about the obstacle in proximity to the vehicle  1 . It is also possible to provide a fisheye lens on top of the vehicle roof, so as to allow capturing of the image around the vehicle  1  for 360 degrees. Alternatively, more than four in-vehicle cameras  48  may be used to obtain comprehensive obstacle information. 
         [0343]    Instead of the in-vehicle cameras  48 , an object-detecting apparatus, such as a sensor or radar, may also be used to obtain the obstacle information. It is advantageous to obtain the obstacle information using an object-detecting apparatus, such as a sensor or radar, because it is possible to obtain information that is difficult to obtain from a static image (for example, information about other approaching vehicles on the road). It is also possible to obtain the obstacle information using both the in-vehicle cameras  48  and an object-detecting apparatus. 
         [0344]    If a turning axis, which allows a vehicle to make a turn, cannot be found using the obstacle information obtained from the in-vehicle camera  48 , it is also possible to search a turning axis by creating a movable area map from the obstacle information obtained from the object-detecting apparatus. As described above, the obstacle information obtained from the image captured by the in-vehicle cameras  48  includes information that cannot be detected by an object-detecting apparatus, such as a sensor or a radar (for example, a boundary line of the parking space or a center line). Therefore, if the obstacle information is obtained from the in-vehicle cameras  48 , a stricter requirement will be used upon finding an applicable turning axis, compared with a scenario using the obstacle information obtained by the object-detecting apparatus. Thus, if a usable turning axis cannot be found using the in-vehicle cameras  48 , the requirement can be loosened by using the obstacle information obtained from the object-detecting apparatus, increasing the possibility to find a usable turning axis. 
         [0345]    According to the embodiments described above, the turning control process ( FIG. 21 ) may be triggered by the steering wheel  51  being turned. Alternatively, a turn-signal by a turn-signal lever (not shown) may also be used as a trigger. Another alternative is to provide a left-turn and a right-turn switch. A turning direction specified by a traffic rule, such as one-way street included in the map DB, may also be recognized as a turnable direction. 
         [0346]    According to the embodiments described above, the vehicle turning pattern includes the x-direction protruding length Ex and the y-direction protruding length Ey. Alternatively, it is possible to use more detailed data about a vehicle turning swept path to check against the movable area map. Another alternative is to calculate a swept path corresponding to each of an infinite number of turning axes, and check against the movable area map.