Abstract:
An automatic lane following system for a vehicle is adapted to control the direction of a moving vehicle along a predetermined path. An associated controller estimates the vehicle&#39;s lateral position in relation to the lane markings (usually the white painted lines). An optical sub-system or a video camera or equivalent sensor is mounted on a vehicle and used to detect the lane markings. An actuator coupled to the steering mechanism is used to control the steering position of the front road wheels in response to a steering signal from a controller. An interruption switch is closed to enable the steering system actuator. An interruption switch actuator is displaceable between a rest or stored position in which the interruption switch is open and an operable position in which the interruption switch is closed.

Description:
FIELD OF THE INVENTION 
     The present invention relates to an automatic lane following system for a vehicle. The automatic lane following system is adapted to control the direction of a moving vehicle along a predetermined path. 
     BACKGROUND OF THE INVENTION 
     Automatic lane following systems have been demonstrated operating at motor way speeds. Such systems certainly prevent lane departure while lane markings (usually the white painted lines) are present. A controller of the systems estimates the vehicle&#39;s lateral position in relation to the lane markings. An optical sub-system or a video camera or equivalent sensor is mounted on a vehicle and used to detect the lane markings. An actuator coupled to the steering mechanism is used to control the steering position of the front road wheels. The lane following system is enabled when a system main switch is closed. When a direction indicator of the vehicle is actuated, the lane following system is disabled. 
     SUMMARY OF THE INVENTION 
     Preferably, the lane following system includes an interruption switch as mounted on the steering instrumentality within the reach of the driver&#39;s finger(s) so that the driver can keep on activating the interruption switch to enable the lane following system. The driver may deactivate the interruption switch by keeping the finger(s) off to take over control of the steering mechanism. The provision of the interruption switch on the steering instrumentality makes it possible for the driver to activate or deactivate the main system switch with the hands gripping the rim of the steering instrumentality, ensuring a smooth shift from the automatic lane following steering operation to the manual steering operation. 
     In order to avoid unintended activation of the interruption switch, the location of an actuator for the interruption switch must be determined. If the interruption switch actuator is disposed within a site sufficiently remote from the rim of the steering instrumentality, a driver work load increases when the driver keeps on activating the interruption switch. 
     Accordingly, a need remains to avoid human unintended activation of the interruption switch and to reduce a driver work load when the driver keeps on activating the interruption switch. 
     According to one aspect of the present invention, there is provided a lane following system for a vehicle, comprising: 
     a steering instrumentality; 
     a steering system including a steering mechanism for controlling the steering position of front road wheels of the vehicle in response to manual operation of said steering instrumentality, 
     said steering system including an actuator for controlling the steering position of the front road wheels in response to a steering signal; 
     a controller operative to generate the steering signal; 
     an interruption switch operatively coupled to said controller to deactivate said actuator when said interruption switch has a first position thereof and to activate said actuator when said interruption switch has a second position; and 
     an interruption switch actuator mounted on said steering instrumentality and operatively associated with said interruption switch, said interruption switch actuator having a rest position in which said interruption switch actuator deactivates said interruption switch to keep said interruption switch at said first position, said interruption switch actuator having an operational position in which said interruption switch actuator activates said interruption switch to keep said interruption switch at said second position, said interruption actuator being displaceable between said rest position and said operational position. 
     According to another aspect of the present invention, there is provided a lane following system for a vehicle, comprising: 
     a steering instrumentality; 
     a steering system including a steering mechanism for controlling the steering position of front road wheels of the vehicle in response to manual operation of said steering instrumentality, 
     said steering system including an actuator for controlling the steering position of the front road wheels in response to a steering signal; 
     a controller to generate the steering signal; and 
     a human interface operatively coupled to said controller, said human interface including a handle mounted on said steering instrumentality and means for deactivating said actuator when said handle is in a rest position and activating said actuator when said handle is held in an operable position by manual operation. 
     According to still another aspect of the present invention, there is provided a method of facilitating steering of a vehicle having front road wheels by tracking a contrived center line of a road, the vehicle having a steering system including an actuator and a steering instrumentality, and the contrived center line being a center line between lane markings defining a lane boundary on the road, comprising: 
     encouraging the driver to keep on manually holding an interruption switch actuator in an operational position to close an interruption switch while gripping the steering instrumentality, thereby to cause the actuator of the steering system to control the steering position of the front road wheels in response to a steering signal from a controller; and 
     manually initiating displacement of the interruption switch actuator from the operable position to a rest position to open the interruption switch, thereby to cause the steering system to control the steering position of the front road wheels in response manual operation of the steering instrumentality. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a block diagram of a first preferred implementation of the present invention. 
     FIG. 2 is a system block diagram of a lane following system. 
     FIG. 3 is a perspective view of an actuator for an interruption switch. 
     FIG. 4 illustrates the actuator as mounted on a steering instrumentality. 
     FIG. 5A illustrates the actuator in its stored position to deactivate the interruption switch. 
     FIG. 5B illustrates the actuator in its operational position to activate the interruption switch. 
     FIG. 6 is a block diagram of a second preferred implementation according to the present invention. 
     FIG. 7 is a block diagram of a third preferred implementation according to the present invention. 
     FIG. 8 is a block diagram of a fourth preferred implementation according to the present invention. 
     FIG. 9 is a plan view of an actuator for an interruption switch according to the fourth preferred implementation. 
     FIG. 10 is a perspective view of another example of an actuator for an interruption switch. 
     FIG. 11 is a plan view of a steering instrumentality with a mounting site for an actuator for an interruption switch, illustrating a fifth preferred implementation according to the present invention. 
     FIG. 12A is a section of a still another example of an actuator for an interruption switch. 
     FIG. 12B is a plan view of the actuator shown in FIG.  12 A. 
     FIG. 13 is a plan view of a steering instrumentality equipped with an actuator for an interruption switch that is located on each of two laterally spaced sites. 
     FIG. 14A illustrates the actuator of FIG. 13 in its stored position. 
     FIG. 14B illustrates the actuator of FIG. 13 in its operational position. 
     FIG. 15A illustrates the actuator of FIG. 13 in its stored position. 
     FIG. 15B illustrates the actuator of FIG. 13 in its operational position. 
     FIG. 16 is a plan view of a steering instrumentality equipped with an actuator for an interruption switch that is located on each of two laterally spaced sites, illustrating a modification of the fifth preferred implementation according to the present invention. 
     FIG. 17A illustrates the actuator of FIG. 16 in its stored position. 
     FIG. 17B illustrates the actuator of FIG. 16 in its operational position. 
     FIG. 18 is a plan view of a steering instrumentality equipped with an actuator for an interruption switch that is located on each of two laterally spaced sites, illustrating a sixth preferred implementation according to the present invention. 
     FIG. 19A illustrates the actuator of FIG. 18 in its stored position. 
     FIG. 19B illustrates the actuator of FIG. 18 in its operational position. 
     FIG. 20 is a perspective view of the actuator of FIG.  18 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the accompanying drawings, for brevity of description, the same or like reference numerals and characters are used to denote similar or like parts or portions throughout all Figures. 
     (First Preferred Implementation) 
     Referring to FIG. 1, the reference numeral  1  denotes a steering instrumentality, in the form of a steering wheel manipulated by a driver. The steering instrumentality  1  is coupled to a steering system  3 . The steering system  3  comprises a steering mechanism, not shown, for controlling the steering position of the front road wheels of a vehicle in response to manual operation of the steering instrumentality  1 . The steering system  3  includes an actuator. The actuator controls the steering position of the front road wheels in response to a steering signal generated by a controller  5 . The actuator may comprise a sub-system to control supply of oil to and discharge thereof from a power cylinder of a power assisted steering system. 
     The controller  5  is a microprocessor based control system that includes as usual a central processor unit (CPU), a read only memory (ROM), a random access memory (RAM), and an input/output unit (I/O). The ROM stores programs of a lane following control routine. Generally denoted by the reference numeral  7 A is a group of sensors, which include a vehicle positioning sensor  9  to detect the position of a vehicle and a lane positioning sensor  11  to detect the presence of lane markings on a road. Generally denoted by the reference numeral  7 B is a list of vehicle information that includes a vehicle speed signal, a direction indicator signal, a transmission shift signal, and a brake signal. Information detected by the group of sensors  7 A and the vehicle information processor  7 B is fed to the controller  5 . 
     The steering instrumentality  1  is provided with an interruption switch  13 . When the switch  13  is activated to a closed position, the lane following system is enabled so that the controller  5  activates the actuator of the steering system  3 . When the switch  13  is deactivated to an open position, the lane following system is disabled so that the controller  5  deactivates the actuator of the steering system. An actuator  15  for the switch  13  is provided. Referring to FIGS. 3,  4 ,  5 A, and  5 B, the interruption switch actuator  15  has a rest position as illustrated in FIG. 5A, i.e., a stored position into the steering instrumentality  1 , and an operational position as illustrated in FIG.  5 B. The switch actuator  15  is displaceable between the stored position and the operational position. In the stored position, the actuator  15  deactivates the interruption switch  13  to keep it open. In the operational position, the actuator  15  activates the interruption switch  13  to keep it open in response to manual operation of the actuator  15 . A switch signal indicative of the open or closed position of the switch  13  is fed to the controller  5 . 
     FIG. 2 illustrates a lane following system having a system main switch  17 . A controller  5  may be divided into a decision logic  5   a  for determining whether or not the current condition allows the lane following operation, and a control routine  5   b  for controlling the lane following operation. A switch signal from the system main switch  17  is fed to the decision logic  5   a . An interruption switch  13  is operatively disposed between the decision logic  5   a  and the control routine  5   b.    
     In operation, the actuator of the steering system  3  is disabled when the system main switch  17  is deactivated or turned OFF or the interruption switch  13  is deactivated or turned OFF. Under this condition, the steering system  3  can control the steering position of the front road wheels in response to manual operation of a steering instrumentality  1 . When the system main switch  17  is activated or turned ON, the decision logic  5   a  keeps on checking information carried by the sensor signals from the positioning sensor  9  and lane positioning sensor  11 , vehicle speed signal, direction indicator signal, shift signal, and brake signal to determine whether or not the current condition allows the lane following operation. 
     In the case where it is determined that the current condition allows the lane following operation, when the interruption switch  13  is activated or turned ON by manual operation of the vehicle driver, the control routine  5   b  runs to generate the control signal applied to the actuator of the steering system  3 . Accordingly, the vehicle is steered by the actuator of the steering system  3  to follow the recognized lane markings. 
     It is the understanding of the inventors that a driver should keep on gripping a steering instrumentality  1  while the actuator of the steering system  3  controls steering position of the front road wheels when the lane following system is enabled. This is because the driver can smoothly cope with the manual steering operation immediately after interruption of the lane following operation. It is also preferred, according to the understanding of the inventors, that the interruption switch  13  should not be activated unintentionally while the driver conducts manual operation of the steering instrumentality  1  to control steering position of the front road wheels. 
     According to the first preferred implementation, an actuator  15  for an interruption switch  13  is provided. The interruption switch actuator  15  has a stored position recessed in relation to a steering instrumentality  1  and an operational position. Referring to FIGS. 3 to  5 B, description on the first preferred implementation is made. 
     The interruption switch actuator  15  is mounted on the steering instrumentality  1 . FIG. 5A illustrates the stored position of the actuator  15 . FIG. 5B illustrates the operational position of the actuator  15 . The actuator  15  includes a handle  19  that is displaceable between its stored position as illustrated in FIG.  5 A and its operational position as illustrated in FIG.  5 B. 
     As will be readily seen from FIG. 4, the actuator  15  is mounted on the steering instrumentality  1  on the rear side thereof within a site adjacent a rim  1   d.    
     At both ends, the handle  19  has protrusions  19   a  of elastomer or rubber. As the discussion proceeds, it will be understood that the protrusions  19   a  are compressed to hold the handle  19  in its stored position as illustrated in FIG.  5 A. 
     At one ends, a pair of arms  21  support the handle  19 . At portions near the opposite ends, the pair of arms  21  is connected to a hinge  23  attached to a mounting plate  25 . Accordingly, the handle  19  can rotate about the hinge  23  as shown in FIG.  3 . The mounting plate  25  is formed with mounting holes  27 . A push rod  29  is fixedly attached to one of the arms  21  and extends from the portion near the hinge  23  for cooperative association with the interruption switch  13 . The interruption switch  13  is fixedly mounted on the steering instrumentality  1 . 
     In FIG. 4, the mounting plate  25  is fixedly attached to a core  1   b  of a spoke  1   a  of the steering instrumentality  1  by means of a plurality of fasteners  31 . Examples of such fasteners are pins and bolts. A steering body cover  1   c  has a recessed portion  33  for receiving the handle  19   a  and the arms  21  (FIGS.  4  and  5 A), so that, when the actuator  15  is in its stored position, the handle  19  and arms  21  will not project beyond the general surface of the steering body cover  1   c .    
     The preceding description clearly shows that the interruption switch actuator  15  is attached to a rear side of the steering instrumentality  1 , which rear side is concealed from the driver&#39;s eyes sitting in the normal seating position. 
     As best seen in FIG. 5A, in the stored position, the handle  19  defines within the recessed portion  33  a clearance or space  33   a  through which the driver can insert the fingers to lift the handle  19  from the stored position. Wall means defining the recessed portion  33  include two sidewalls  33   b , which are spaced apart in a direction along an axis of the hinge  13  to be in opposed relation to the both ends of the handle  19 , respectively, in the stored position of the actuator  15 . In the stored position of FIG. 5A, the protrusions  19   a  are compressed between the ends of the handle  19  and the adjacent sidewalls  33   b  to hold the handle  19  it is stored position. Accordingly, the protrusions  19   a  serve as a releasable elastic latch of the handle  19 . It will also be noted that the arms  21  and hinge  23  cooperate with each other to serve as a guide of the handle  19  to enable displacement of the handle  19  between the stored and operable positions. 
     As will be readily seen from FIGS. 5A and 5B, the axis of the hinge  23  lies between a steering shaft, not shown, and the rim  1   d  so that the handle  19  is disposed on the steering shaft side of the hinge  23  in the stored position of FIG.  5 A and it is disposed on the rim  1   d  side of the hinge  23 . In the stored position of FIG. 5A, the push rod  29  presses the interruption switch  13 , thus deactivating or turning OFF the interruption switch  13 . Under this condition, the driver can conducts manual operation of the steering instrumentality  1  to control steering position of the front road wheels. The handle  19  of the actuator  15  is fit into the recessed portion  33  of the steering body cover  1   c  in the stored position of FIG. 5A, thereby to avoid unintended manual operation of the handle  19 . 
     In order for automatic lane following operation, manual operation to hold the handle  19  at the operational position of FIG. 5B is needed. For a shift from the stored position of FIG. 5A to the operational position of FIG. 5B, the driver insert its finger or fingers into the space  33   a  to lift the handle  19  from the recessed portion  33  for subsequent rotation around the hinge  23  toward the operational position of FIG.  5 B. In the process, the push rod  29  disengages from the interruption switch  13  to activate or turning ON the interruption switch  13 . Accordingly, the actuator of the steering system  3  controls steering position of the front wheels in response to the steering signal from the controller  5 , thereby to cause the vehicle to automatically follow the lane markings on a road. 
     In the operational position, the handle  19  is disposed in the proximity of the rim  1   d  within an area where the driver normally grips the rim  1   d . Thus, the driver can keep on holding the handle  19  at the operational position while making a natural grip on the rim  1   d  without any considerable work load. 
     For a return shift from the operational position of FIG. 5B to the stored position of FIG. 5A, the hinge  23  facilitates displacement of the handle  19 , thus providing a quick and smooth shift. 
     (Second Preferred Implementation) 
     Referring to FIG. 6, description on the second preferred implementation is made. This second preferred implementation is substantially the same as the first preferred implementation except the provision of a modified interruption switch actuator  15  instead of the actuator  15  according to the first preferred implementation. 
     The modified interruption switch actuator  15  according to the second preferred implementation is substantially the same the actuator  15  according to the first preferred implementation except the provision of an arrangement  35  to bias a handle from one of stored and operational positions to the other when released by an activator  37 . The activator  37  may include a lock mechanism that is released when a switch is pressed by a manual operation to release the biasing arrangement  35 . The biasing arrangement  35  may include one or any appropriate combination of rubber, spring, magnet, and a fluid spring. If desired, a motor may be used to cause the biasing arrangement  35  to bias the interruption switch actuator  15  in any desired direction between the stored and operational positions. 
     (Third Preferred Implementation) 
     Referring to FIG. 7, description on the third preferred implementation is made. This third preferred implementation is substantially the same as the first preferred implementation except the provision of a modified interruption switch actuator  15  instead of the actuator  15  according to the first preferred implementation. 
     The modified interruption switch actuator  15  according to the third preferred implementation is substantially the same the actuator  15  according to the first preferred implementation except the provision of an arrangement  35  to always and resiliently bias a handle  19  toward the stored position from the operational position. 
     Since the handle  19  is resiliently biased toward its stored position, only keeping fingers off the handle  19  will cause its quick displacement to the stored position. 
     (Fourth Preferred Implementation) 
     Referring to FIGS. 8 and 9, description on the fourth preferred implementation is made. According to this fourth preferred implementation, an interruption switch actuator  15  includes an arrangement  35  to always and resiliently bias a handle  19  toward its stored position from its operational position in addition to a guide  39  for smooth displacement of the handle. 
     As best seen in FIG. 9, arms  21  and a hinge  23  constitute the guide  39 . A torque spring  35 A constitutes the biasing arrangement  35 . The torque spring  35 A encircles the hinge  23  and has one arm  36   a  lying against a mounting plate  25  and an opposite arm  36   b  bearing against the arm  21  to apply torque to the handle  19  in a direction toward the stored position. It is to be noted that the interruption switch actuator  15  shown in FIG. 9 is substantially the same as that shown in FIGS. 3 to  5 B except the provision of the torque spring  35 A. 
     Since the handle  19  is resiliently biased toward its stored position at all times, only keeping fingers off the handle  19  will cause its quick displacement to the stored position. 
     FIG. 10 illustrates a modification of a biasing arangement  35 . The modified biasing arangement incorporates a motor mechanism. A motor  41  is fixedly attached to a motor mounting bracket  43 . The bracket  43  is fixedly secured to a spoke core  1   b  by appropriate mechanical fasteners, such as pins, bolts and nuts. The motor output shaft  45  is coupled to a hinge  23 . 
     Activation of the motor  41  causes the hinge  23  to rotate to move a handle  19  between its stored position and its operational position. A motor controller  47  serves as an activator to control activation of the motor  41 . Direction of movement of the handle  19  controlled by a switch that may be positioned on the steering shaft side of the hinge  23 . 
     Further, a vibrator b is mounted on the spoke core  1   b . A warning device a controls vibration of the vibrator b. A vibrator may be disposed within the handle  19 . 
     (Fifth Preferred Implementation) 
     Referring to FIGS. 11 to  15 B, description on the fifth preferred implementation is made. According to this fifth preferred implementation, an interruption switch actuator  15  of the slide type is proposed. 
     As best seen in FIG. 12B, the actuator  15  includes a base  51  formed with a longitudinal groove  49 . The base  51  supports an arm  53  for sliding movement. At one end, the arm  53  has a handle  19 . A guide rod  55 , which extends from the arm  53  downwardly viewing in FIG. 12A, is guided by the groove  49 . The groove  49 , which serves as a guide, is formed inwardly into a spoke portion  1   a  as seen in FIG. 13. A spring  57  serves as a biasing arangement. Via the spring  57 , the arm  53  has a push rod  59 . The spring  57  is operatively disposed between the guide rod  55  and the push rod  59 . The push rod  59  is opposed to an interruption switch  13 . The actuator  15  of this slide type is fixedly attached to a core  1   b  of the spoke  1   a  of the steering instrumentality  1  by means of appropriate fasteners, such as pins or bolts and nuts. 
     Referring to FIGS. 14A and 14B, the vehicle driver manually pulls the handle  19  toward a rim  1   d  of the steering instrumentality  1 . In this process, the guide rod  55  is guided by the groove  49  to push via the spring  57  the push rod  59 , thus activating or turning ON the interruption switch  13 . In this manner, activation of the interruption switch  13  enables a lane following system. The driver keeps on gripping the handle  19  against the bias of the spring  57  in the operable position of FIG.  14 B. Upon keeping the fingers off the handle  19 , the spring  57  moves the handle  19  to the stored position of FIG. 14A immediately. 
     As best seen in FIG. 13, the actuators  15  are attached to the front side of the steering instrumentality  1 , which front side is exposed to the driver&#39;s eyes. This provision of the actuators is advantageous in facilitating driver&#39;s recognition of operation of the interruption switch  13 . 
     FIGS. 16,  17 A, and  17 B illustrate a modification of the fifth preferred implementation. In this modification, actuators  15  of the slide type are mounted on the rear of the steering instrumentality  1 . The actuators of this modification are substantially the same as those shown in FIGS. 12A to  15 B. The provision of the actuators on the rear side of the steering instrumentality  1  will not restrict the degree of freedom in designing the exposed front side of the steering instrumentality  1 . 
     (Sixth Preferred Implementation) 
     Referring to FIGS. 18 to  20 , description on the sixth preferred implementation is made. The sixth preferred implementation employs an interruption switch actuator  15  that is substantially the same as the actuator shown in FIG.  9 . The actuators  15  are mounted on a steering instrumentality  1  in the same manner as described in relation to the first preferred implementation. According to the sixth preferred implementation, a handle  19  is in the form of a lever-like member having a surface with a curvature that is generally the same as the curvature of the rim  1   d  of the steering instrumentality  1 . FIG. 19A illustrates the stored position, while FIG. 19B illustrates the operational position. 
     The surface curvature of the handle  19  according to this sixth preferred implementation provides a fit feeling to hands of the vehicle driver. Thus, if a vibrator is disposed within the handle  19 , warning information is transmitted to the driver in good manner. 
     From the preceding description, it is now understand that an interruption switch  13  and an interruption switch actuator  15  with a handle  19  constitute a human interface operatively coupled to a controller  5 . When the handle  19  is in a rest or stored position, the interruption switch actuator  15  deactivates the interruption switch  13 , thereby to deactivate an actuator of a steering system  3  for controlling the steering position of the front road wheels. When the handle  19  is held in an operable position by manual operation of a driver, the interruption switch actuator  15  activates the interruption switch  13 , thereby to activate the steering system actuator. Under this condition, the steering system actuator controls the steering position of the front road wheels to follow the lane marking on a road. 
     While the present invention has been particularly described in conjunction with the preferred implementations, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art in light of the foregoing description. It is therefore contemplated that the appended claims will embrace any such alternatives, modifications and variations as falling within the true scope and spirit of the present invention. 
     The content of disclosure of Japanese Patent Application No. 11-131615, filed May 12, 1999 is hereby incorporated by reference in its entirety.