Patent Publication Number: US-2021179397-A1

Title: Crane vehicle

Description:
TECHNICAL FIELD 
     The present invention relates to a self-traveling crane vehicle. 
     BACKGROUND 
     A self-traveling crane vehicle includes a traveling body and a crane device mounted on the traveling body. The crane device is supported by the traveling body through a swivel base, and the swivel base may be provided with a driver seat. 
     Japanese Patent No. 2003-238077 discloses a crane vehicle in which an ultrasonic sensor is arranged at a front end of a boom of a crane device. The ultrasonic sensor irradiates ultrasonic waves forward in the traveling direction of a traveling body, receives a reflected wave reflected by an object to be detected, and detects the distance to the object to be detected. Accordingly, it is determined whether the object to be detected is an obstacle during traveling or crane work of the crane vehicle. 
     Meanwhile, the crane device is mounted at the centre of the traveling body, and the driver seat is arranged on one side (for example, the right side of the traveling body) in the width direction of the traveling body. Thus, during traveling or during crane work, the other side in the width direction (for example, the left side of the traveling body) becomes a blind spot for the operator. 
     In the crane vehicle described in Japanese Patent No. 2003-238077, obstacles cannot be sufficiently detected in the region which is a blind spot from the driver seat. 
     SUMMARY OF INVENTION 
     The present invention has been made based on the above background and an objective thereof is to provide a crane vehicle that achieves safe movement by reliably detecting an obstacle in a region which is a blind spot from a driver seat, namely, a region on the opposite side of the driver seat across a crane device. 
     (1) The crane vehicle according to the present invention includes a traveling body on which a crane device is mounted, a driver seat arranged on one side in a width direction of the traveling body, a first sensor that outputs a signal corresponding to a distance to an obstacle located on the other side in the width direction, a controller, and a display. The controller displays an obstacle display image including a first object that represents a picture of the crane vehicle stored in a memory and a second object that represents a picture of the obstacle detected by the first sensor on the display. The distance between the first object and the second object corresponds to the distance detected by the first sensor. 
     Because the obstacle display image including the first object and the second object is displayed on the display, the operator of the crane vehicle can easily recognize the position of the obstacle with respect to the crane vehicle. In addition, because the distance between the first object that represents the crane vehicle and the second object that represents the obstacle corresponds to the distance detected by the first sensor, the operator can easily recognize the distance from the crane vehicle to the obstacle. 
     (2) The controller sets the color of the second object to a first predetermined color when the distance to the obstacle is equal to or greater than a threshold distance stored in the memory, and sets the color of the second object to a second predetermined color different from the first predetermined color when the distance to the obstacle is less than the threshold distance stored in the memory. 
     When an obstacle approaches, the color of the obstacle is changed from the first predetermined color to the second predetermined color, thus enabling the operator to instantly recognize that the obstacle is approaching. 
     (3) The crane vehicle according to the present invention may further include an input device. The controller receives, through the input device, a selection of one image from a bird&#39;s-eye view image viewed from above, a front image of a viewpoint directed forward, and a side image directed toward the other side, and displays the received image on the display as the obstacle display image. 
     According to the above configuration, an image that the operator feels easy to see can be displayed on the display. 
     (4) The controller may receive an enlargement instruction instructing the enlargement of a partial region of the obstacle display image through the input device, and displays, in response to reception of the enlargement instruction, an enlarged image obtained by enlarging the region on the other side in the width direction of the traveling body on the display. 
     When an operator inputs an enlargement instruction through the input device, a region which is a blind spot from the driver seat is enlarged and displayed on the display. That is, the region which is a blind spot from the driver seat is enlarged without prompting the operator to designate the region to be enlarged. Thus, operation of the driver is facilitated. 
     (5) The crane device according to the present invention may further have a speaker. The controller causes the speaker to generate a warning sound when the distance to the obstacle is less than the threshold distance stored in the memory. 
     The sound also notifies that the obstacle is approaching. Thus, the operator can recognize the approaching of the obstacle more reliably. 
     (6) The driver seat has a steering wheel for determining the steering angle of the wheels of the traveling body. The crane device may further include a second sensor for outputting a signal that corresponds to the steering angle of the steering wheel and a third sensor for outputting a signal that corresponds to the speed of the traveling body. The controller determines whether the obstacle detected by the first sensor is a moving object or a fixed object from the signals input from the first sensor, the second sensor, and the third sensor, and sets the second predetermined color to a third predetermined color different from the second predetermined color in response to a determination that the object is a moving object. 
     If the distance from the crane vehicle to the obstacle is short and the obstacle is a moving object, the color of the first object is changed from the second predetermined color to the third predetermined color different from the second predetermined color. Therefore, the operator can easily recognize that the obstacle requires more attention. 
     (7) The crane device has a boom that can be raised, lowered and stretched. The first sensor is arranged at the front end of the boom. In response to reception of a signal output from the first sensor and corresponding to the distance from the front end of the boom to a load suspended by the boom, the controller may display the distance on the display. 
     The distance from the front end of the boom to the load suspended by the boom can be detected by the first sensor configured to detect an obstacle during movement of the crane vehicle, and the distance can be displayed on the display. 
     (8) The crane vehicle according to the present invention may further include a fourth sensor for receiving infrared rays incident from the other side in the width direction. The controller determines whether the obstacle detected by the first sensor is a person or not in accordance with a signal input from the fourth sensor, and sets the second predetermined color to a fourth predetermined color different from the second predetermined color in response to a determination that the obstacle is a person. 
     When the distance from the crane vehicle to the obstacle is short and the obstacle is a person, the color of the first object is changed from the second predetermined color to the fourth predetermined color different from the second predetermined color. Therefore, the operator can easily recognize that the obstacle requires more attention. 
     (9) The crane vehicle according to the present invention may further include a plurality of cameras for capturing images of the periphery of the traveling body. The obstacle display image includes the images captured by the cameras. 
     This enables the driver (manipulator) to recognize the situation around the crane vehicle as well. 
     Advantageous Effects of Invention 
     According to the present invention, safe movement can be achieved by reliably detecting an obstacle in a region which is a blind spot from a driver seat, namely, a region on the opposite side from the driver seat across a crane device. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a right side view of a crane vehicle  10  according to an embodiment. 
         FIG. 2  is a schematic view of the inside of a cabin  13 . 
         FIG. 3  is a schematic plan view of the crane  10  according to the embodiment. 
         FIG. 4  is a functional block diagram of the crane  10  according to the embodiment. 
         FIG. 5  is a flowchart of display processing. 
         FIG. 6  is a flowchart of obstacle detection processing. 
         FIG. 7(A)  is a diagram showing a bird&#39;s-eye view image displayed on a display  48 , and 
         FIG. 7(B)  is a diagram showing an enlarged bird&#39;s-eye view image. 
         FIG. 8  is a flowchart of display processing of Modification example 1. 
         FIG. 9  is a perspective view of a crane vehicle  70  of Modification example 2. 
         FIG. 10  is a flowchart of display processing of Modification example 2. 
         FIG. 11  is a flowchart of display processing of Modification example 3. 
         FIG. 12  is a schematic plan view of the crane vehicle  10  according to Modification example 4. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Hereinafter, a preferred embodiment of the present invention is described with reference to the drawings as appropriate. Moreover, the present embodiment is only one aspect of the present invention, and it is evident that the embodiment may be changed without changing the gist of the present invention. 
     A crane vehicle  10  of the present embodiment is shown in  FIG. 1 . The crane vehicle  10  mainly includes a traveling body  11 , a crane device  12  mounted on the traveling body  11 , and a cabin  13  for an operator who drives the traveling body  11  and manipulates the crane device  12  to sit in. That is, the crane vehicle  10  is a rough terrain crane in which the driving of the traveling body  11  and the manipulation of the crane device  12  are performed in the cabin  13 . 
     In a rough terrain crane, a crane device is equipped on a moving body, a vehicle body is long, and only one cabin is arranged, thus making the range of the blind spot from the operator wider than in general vehicles. In the present embodiment, the crane vehicle  10  that can be safely driven and manipulated is described. 
     Traveling Body  11   
     The traveling body  11  mainly includes a vehicle body  20 , an engine (not shown) mounted on the vehicle body  20 , a pair of left and right rear wheels  22  that are rotationally driven by the engine, and four steerable front wheels  21 . The front wheels  21  and the rear wheels  22  are rotatably held by the vehicle body  20 . The front wheels  21  and the rear wheels  22  correspond to the “wheels” of the present invention. 
     During normal travelling of travelling on a road or the like, the direction of the traveling body  11  is changed by steering the front wheels  21 . 
     In addition, the traveling body  11  includes a hydraulic pump (not shown) mounted on the vehicle body  20 , and a swivel base motor  23  ( FIG. 4 ) being a hydraulic motor driven by hydraulic oil supplied from the hydraulic pump. The swivel base motor  23  swings a swivel base  31  of the crane device  12 . The hydraulic pump supplies hydraulic oil to various hydraulic cylinders and hydraulic motors included in the crane device  12  in addition to the swivel base motor  23 . 
     Hereinafter, the width direction of the crane vehicle  10  is described as the left-right direction, and the direction in which the crane vehicle  10  advances during normal traveling is described as the front. 
     The traveling body  11  includes a pair of front and rear outriggers  24  for stabilizing the posture of the crane vehicle  10  during operation. The outrigger  24  includes an outer cylinder (not shown) fixed to the vehicle body  20  and extending in the left-right direction, a pair of left and right inner cylinders (not shown) held by the outer cylinder so as to be slidable in the left-right direction, and a pair of left and right jacks  25  arranged at the front ends of the inner cylinders. The jack  25  is a jack cylinder capable of stretching and contracting in the up-down direction. A ground plate  26  is arranged at the lower end of the jack  25 . The jack  25  is pulled out from the vehicle body  20  by the hydraulic cylinder (not shown) and then extended to ground the ground plate  26  to an iron plate or the like placed on the ground. 
     When the crane vehicle  10  is moved, the jacks  25  are brought into a housed state in which the jacks  25  are close to the vehicle body  20 , and the crane vehicle  10  is supported by the front wheels  21  and the rear wheels  22 . On the other hand, during working, the crane vehicle  10  is supported by the four jacks  25  that are pulled out and extended. 
     In addition, the traveling body  11  includes a battery  27  ( FIG. 4 ) that is charged by driving the engine. The battery  27  supplies a direct-current voltage to a power supply circuit  65  described later. 
     Crane Device  12   
     The crane device  12  includes a swivel base  31  swivably supported by the vehicle body  20 , and a boom  32  supported by the swivel base  31  so as to be capable of rising up and falling down. 
     The swivel base  31  is located on the upper surface of substantially the central portion of the vehicle body  20  in the front-rear direction. The swivel base  31  is swivably supported by, for example, a swing bearing (not shown) arranged in the vehicle body  20 . The swivel base  31  is rotated by the swivel base motor  23  arranged in the vehicle body  20 . 
     A swivel (not shown) is arranged between the vehicle body  20  and the swivel base  31  so as to circulate hydraulic oil, cooling water, or electricity (power and signals) between the vehicle body  20  and the swivel base  31 . Because the structure of the swivel is publicly known, detailed description thereof is omitted. 
     The boom  32  is located on the left side of the swivel base  31  and is supported by the swivel base  31  so as to be capable of rising up and falling down. The boom  32  is made to rise up and fall down by a derricking cylinder  33  ( FIG. 4 ) arranged between the swivel base  31  and the boom  32 . The derricking cylinder  33  is a hydraulic cylinder, and stretches and contracts when the hydraulic oil is supplied through the swivel from the hydraulic pump arranged in the vehicle body  20 . 
     The boom  32  has a plurality of frames arranged in a nested manner and is capable of stretching and contracting. The boom  32  is provided with a telescopic cylinder  34  that moves the frame. The telescopic cylinder  34  is a hydraulic cylinder and stretches and contracts when the hydraulic oil is supplied through the swivel from the hydraulic pump arranged in the vehicle body  20 . 
     A hook  35  ( FIG. 4 ) connected to one end of a wire is arranged at the front end of the boom  32 . The other end of the wire is connected to a winch  36  ( FIG. 4 ). The winch  36  is driven by supplying the hydraulic oil from the hydraulic pump through the swivel. The hook  35  is lifted and lowered by driving the winch  36 . 
       FIG. 1  shows a state of the crane vehicle  10  during normal traveling or during moving at a work site (hereinafter, referred to as a moving state). In the moving state, the boom  32  is contracted and laid down. The front end of the boom  32  in the moving state projects forward from the front surface of the vehicle body  20 . Hereinafter, the boom  32  is assumed to be in the posture in the moving state unless otherwise specified. 
     The cabin  13  is located on the upper surface of the right part of the swivel base  31 . That is, the cabin  13  is aligned with the boom  32  in the left-right direction. Therefore, in the moving state, the left side of the crane vehicle  10  becomes a blind spot from the operator sitting in the cabin  13 . 
     The cabin  13  has a substantially rectangular box shape. As shown in  FIG. 2 , a driver seat  41  on which an operator sits, a driving device  42 , a manipulation device  43 , a display  48 , an input device  49  ( FIG. 4 ) used for switching the display of the display  48  and the like, and a control box (not shown) are housed in the inner space of the cabin  13 . 
     The driving device  42  is used for driving the traveling body  11 . The driving device  42  mainly includes a plurality of pedals  44  and a steering wheel  45 . The pedal  44  is an input unit for receiving an instruction to accelerate or decelerate the traveling body  11 , and is an accelerator pedal, a brake pedal, a clutch pedal, or the like. The steering wheel  45  is an input unit for receiving an instruction to change the steering angle of the front wheels  21  of the traveling body  11 . Because the configuration of the driving device  42  is publicly known, detailed description thereof is omitted. 
     The manipulation device  43  is used to manipulate the crane device  12 . Specifically, the operator&#39;s instructions of stretching/contracting the jacks  25  of the outrigger  24 , swinging the swivel base  31 , stretching or contracting the boom  32 , raising or lowering the boom  32 , and driving the winch  36  are received. The manipulation device  43  is configured of, for example, a lever  46 , a pedal  47 , a switch (not shown), or the like. Because the configuration of the manipulation device  43  is publicly known, detailed description thereof is omitted. 
     The display  48  is arranged in the cabin  13  at a position deviated to the left from the centre in the left-right direction. More specifically, the display  48  is arranged on the left side of the steering wheel  45 . Power is supplied to the display  48  from a power supply circuit  65  described later and an image signal is input to the display  48  from a controller  60  described later. The display  48  displays an image corresponding to the input image signal. Specifically, the display  48  displays a stretching state of the jacks  25 , a swiveling angle of the swivel base  31 , a stretching state (length) of the boom  32 , a derricking angle of the boom  32 , and an obstacle detected by an obstacle sensor  50  described later. 
     The input device  49  has one or a plurality of operation units such as push buttons operated by the operator. Alternatively, the input device  49  has a touch sensor superimposed on the display  48 . The input device  49  receives at least an instruction to select an obstacle display mode for displaying an obstacle image in a moving state, an instruction to select an image between a bird&#39;s-eye view image and a front image, an instruction to select an enlarged display of an image, or the like. 
     A control substrate is housed in the control box (not shown). A resistor, an integrated circuit, a diode, a capacitor, or a microcomputer that realizes the controller  60 , the power supply circuit  65  and a transmission/reception circuit  66  shown in  FIG. 4  are mounted in the control substrate. 
     The power supply circuit  65  is electrically connected to the battery  27  through a cable and a swivel, and is supplied with a direct-current voltage from the battery  27 . The power supply circuit  65  has a DC/DC converter such as a switching regulator to convert the supplied direct-current voltage into a direct-current voltage having a stable predetermined voltage value (12 V, 5 V, 3.3 V, and the like) and outputs the direct-current voltage. The power supply circuit  65  supplies the predetermined direct-current voltage as a drive voltage to the controller  60 , the display  48 , and the transmission/reception circuit  66 . 
     As shown in  FIG. 4 , the controller  60  includes a CPU  61 , a ROM  62  in which a program is stored, a RAM  63 , a memory  64 , and a communication bus (not shown). The CPU  61  executes the program by sequentially executing the instructions described in the address of the program stored in the ROM  62 . The RAM  63  temporarily stores data and the like when the program is executed. The CPU  61 , the ROM  62 , the RAM  63 , and the memory  64  are connected by the communication bus. Moreover, a vehicle speed sensor  53  and a steering sensor  54 , which are indicated by broken lines in  FIG. 4 , are included in the configuration of Modification example 1 and are described in Modification example 1. In addition, an infrared sensor  52  shown by the broken line in  FIG. 4  is included in the configuration of Modification example 3 and is described in Modification example 3. Furthermore, a camera  55  shown by the broken line in  FIG. 4  is included in the configuration of Modification example 4 and is described in Modification example 4. 
     The controller  60  is connected to the driving device  42 , the manipulation device  43 , the input device  49 , the display  48 , the speaker  68 , and the transmission/reception circuit  66 . The controller  60  inputs an operation signal corresponding to the operator&#39;s instruction from the driving device  42 , the manipulation device  43 , and the input device  49 . In addition, the controller  60  outputs an image signal to the display  48  and displays an image on the display  48 . Furthermore, the controller  60  outputs a control signal to the transmission/reception circuit. 
     In addition, the controller  60  outputs an audio signal to the speaker  68 . The speaker  68  is mounted on, for example, the control substrate. The speaker  68  outputs a sound corresponding to the input audio signal. 
     Besides, the controller  60  is connected to the swivel base motor  23 , the derricking cylinder  33 , the telescopic cylinder  34 , the winch  36 , and a member such as a solenoid valve for controlling the operation of the jacks  25 , and controls the operation of the swivel base motor  23 , the derricking cylinder  33 , the telescopic cylinder  34 , the winch  36 , and the jacks  25 . 
     The transmission/reception circuit  66  is electrically connected to obstacle sensors  50 A,  50 B and  50 C (described later) through a cable and the swivel. The transmission/reception circuit  66  includes, for example, a transmission circuit for generating a detection wave, an amplifier circuit for amplifying the detection wave generated by the transmission circuit and supplying the amplified detection wave to the obstacle sensor  50  being an antenna, and a detection circuit for generating and amplifying a detection signal corresponding to the radio waves received by the obstacle sensor  50  and outputting the amplified detection signal to the controller  60 . The transmission/reception circuit  66  is driven by receiving supply of power (direct-current voltage) from the power supply circuit  65 . The transmission/reception circuit supplies the detection wave to the obstacle sensor  50  based on the control signal input from the controller  60 , generates and outputs a detection signal. 
     The memory  64  is a non-volatile memory such as an EEPROM. The memory  64  stores a vehicle object being a schematic picture of the crane vehicle  10 . The vehicle object is used to generate an obstacle image described later. In addition, the memory  64  also stores threshold distance and color data. The threshold distance and the color data are used for determining the color of the obstacle in the obstacle image. 
     Obstacle Sensor  50   
     As shown in  FIG. 3 , the crane vehicle  10  includes three obstacle sensors  50 A,  50 B and  50 C. As shown in  FIG. 1 , the obstacle sensor  50 A is attached to the lower surface of the front end portion of the boom  32 . As shown in  FIG. 3 , the obstacle sensor  50 B is attached to the upper surface of the central portion of the vehicle body  20  in the front-rear direction on the left side of the vehicle body  20 . The obstacle sensor  50 C is attached to the upper surface of the central portion of the vehicle body  20  in the left-right direction on the rear side of the vehicle body  20 . The obstacle sensor  50  corresponds to the “first sensor” of the present invention. 
     The obstacle sensor  50 A arranged on the boom  32  is electrically connected through a cable to the transmission/reception circuit  66  of the control substrate arranged in the cabin  13 . The obstacle sensor  50 B and the obstacle sensor  50 C arranged on the vehicle body  20  are electrically connected through a cable (not shown) and the swivel to the transmission/reception circuit  66  of the control substrate arranged in the cabin  13 . 
     Hereinafter, when the obstacle sensors  50 A,  50 B and  50 C are not distinguished, they are described as the obstacle sensor  50 . 
     The obstacle sensor  50  is a transmission/reception antenna for transmitting and receiving radio waves. The obstacle sensor  50  transmits radio waves (detection wave) through the transmission/reception circuit  66  and receives radio waves (detection wave) reflected by the obstacle. 
     The obstacle sensor  50  being an antenna has directivity. In  FIG. 3 , the directivity of the obstacle sensor  50  is shown by hatching. The obstacle sensor  50 A mainly transmits radio waves toward the front and the left side of the crane vehicle  10 , and receives radio waves incident from the front and the left side of the crane vehicle  10  with high sensitivity. That is, the obstacle sensor  50 A detects obstacles on the left side of the vehicle body  20  and in front of the vehicle body  20 , which are blind spots from the cabin  13 . 
     The obstacle sensor  50 B mainly transmits radio waves toward the left side of the crane vehicle  10  and receives radio waves incident from the left side of the crane vehicle  10  with high sensitivity. That is, the obstacle sensor  50 B detects obstacles on the left side of the vehicle body  20 , which is a blind spot from the cabin  13 . 
     The obstacle sensor  50 C mainly transmits radio waves toward the left side and the rear side of the crane vehicle  10  and receives radio waves incident from the left side and the rear side of the crane vehicle  10  with high sensitivity. That is, the obstacle sensor  50 C detects obstacles on the left side of the vehicle body  20  and on the rear side of the vehicle body  20 , which are blind spots from the cabin  13 . 
     Display Processing 
     Hereinafter, display processing in which the controller  60  displays an image on the display  48  when the crane vehicle is in the moving state is described with reference to  FIG. 5 . Moreover, the execution order of each processing (each step) described below can be appropriately changed without changing the gist of the invention. 
     The controller  60  uses the input device  49  to determine whether the operator has selected the obstacle display mode (S 11 ). Specifically, the controller  60  determines whether a start signal has been input from the input device  49 . That is, the display processing is started when the operator has selected the obstacle display mode. 
     The controller  60  waits until the start signal is input (S 11 : No). When the controller  60  determines that the start signal has been input (S 11 : Yes), the controller  60  executes the obstacle detection processing (S 12 ). Details of the obstacle detection processing are described with reference to  FIG. 6 . 
     Obstacle Detection Processing 
     First, the controller  60  outputs a control signal to the transmission/reception circuit  66  (S 31 ), and causes the transmission/reception circuit  66  to transmit a detection wave from the obstacle sensor  50 . The transmitted detection wave is reflected by the obstacle. The detection wave (reflected wave) reflected by the obstacle is received by the obstacle sensor  50 . The reflected wave received by the obstacle sensor  50  is processed by the transmission/reception circuit  66  and output to the controller  60  as a detection signal. Because the processing performed by the transmission/reception circuit  66  is publicly known, detailed description thereof is omitted. 
     The controller  60  waits until a detection signal is input from the transmission/reception circuit  66  (S 32 : No). When the detection signal is input (S 32 : Yes), the controller  60  detects the direction in which the obstacle is located (S 33 ), the distance to the obstacle (S 34 ), and the size of the obstacle (S 35 ), and ends the obstacle detection processing. 
     For example, the controller  60  calculates the distance to the obstacle, the direction in which the obstacle is located (that is, the position of the obstacle), and the size of the obstacle from a time starting from the transmission of the detection wave by the obstacle sensor  50 A until the reception of the reflected wave, a time starting from the transmission of the detection wave by the obstacle sensor  50 B until the reception of the reflected wave, the intensity distribution of the received reflected wave with respect to the reception angle (reception direction), and the like. In addition, the controller  60  calculates the distance to the obstacle, the direction in which the obstacle is located (that is, the position of the obstacle), and the size of the obstacle from a time starting from the transmission of the detection wave by the obstacle sensor  50 B until the reception of the reflected wave, a time starting from the transmission of the detection wave by the obstacle sensor  50 C until the reception of the reflected wave, the intensity distribution of the received reflected wave with respect to the reception angle (reception direction), and the like. Moreover, the detection of the position of the obstacle and the detection of the size of the obstacle are examples only, and other detection methods may also be used. 
     The controller  60  executes the processing of steps S 33 , S 34  and S 35  for all the detected obstacles. 
     As shown in  FIG. 5 , when the obstacle detection processing is ended (S 12 ), the controller  60  determines whether the detected separation distance is equal to or greater than the threshold distance stored in the memory  64  (S 13 ). That is, the controller  60  determines whether the obstacle is close to the crane vehicle  10 . When the controller  60  determines that the separation distance is equal to or greater than the threshold distance (S 13 : Yes), the controller  60  sets the color of the obstacle to a first predetermined color indicated by color data stored in the memory  64  (S 14 ). On the other hand, when the controller  60  determines that the separation distance is not equal to or greater than the threshold distance (S 13 : No), the controller  60  sets the color of the obstacle to be a second predetermined color indicated by the color data stored in the memory  64  (S 15 ). The second predetermined color is, for example, red or yellow, and the first predetermined color is, for example, green or blue. After the execution of step S 15 , the controller  60  outputs an audio signal to the speaker  68  and causes the speaker  68  to output a warning sound (S 24 ). That is, when the distance to the obstacle is short, the speaker  68  outputs the warning sound. The controller  60  executes the processing of steps S 13  to S 15  and S 24  for all the detected obstacles. 
     Subsequently, the controller  60  determines the type of the image selected by the operator using the input device  49  based on the operation signal input from the input device  49  (S 16 ). Specifically, the controller  60  determines whether the type of the image selected by the operator is a “bird&#39;s-eye view image”, a “front image”, or a “left image”. The bird&#39;s-eye view image is an image captured when the crane vehicle  10  and its surroundings are viewed from above the crane vehicle  10 . The front image is an image captured when the front of the crane vehicle  10  is viewed from the crane vehicle  10 . The left image is an image captured when the left side of the crane vehicle  10  is viewed from the crane vehicle  10 . 
     When the controller  60  determines that the type of the image selected by the operator is the “bird&#39;s-eye view image” (S 16 : bird&#39;s-eye view image), the controller  60  uses the vehicle object stored in the memory  64  to generate an obstacle display image ( FIG. 7(A) ) being a bird&#39;s-eye view image. More specifically, the controller  60  generates an obstacle display image including the vehicle object stored in the memory  64  and the obstacle object that represents the obstacle detected by the obstacle detection processing. At that time, the controller  60  arranges an obstacle object having a size corresponding to the size of the obstacle detected in the obstacle detection processing at the position (direction and distance) of the obstacle detected in the obstacle detection processing. In addition, the controller  60  generates an obstacle object with the color set in step S 14  or S 15 . The vehicle object corresponds to the “first object” of the present invention. The obstacle object corresponds to the “second object” of the present invention. The image shown in  FIG. 7(A)  corresponds to the “obstacle display image” of the present invention. 
     Similarly, when the controller  60  determines that the type of the image selected by the operator is the “front image” (S 16 : front image), the controller  60  generates an obstacle display image being a front image (S 18 ), and generates an obstacle display image being a left image (S 19 ) when the controller  60  determines that the type of the image selected by is the “left image” (S 16 : left image). The left image corresponds to the “side image” of the present invention. 
     After the obstacle display image (S 17 , S 18 , S 19 ) is generated, the controller  60  determines whether the operator has instructed to enlarge the image by using the input device  49  (S 20 ). Specifically, the controller  60  determines whether an operation signal indicating the enlargement of the image is input from the input device  49 . 
     When the controller  60  determines that the operation signal indicating the enlargement of the image has been input from the input device  49  (S 20 : Yes), the controller  60  generates an enlarged image ( FIG. 7(B) ) obtained by enlarging the generated obstacle display image (S 21 ). The controller  60  enlarges a predetermined region of the obstacle display image to generate the enlarged image. Specifically, the controller  60  generates the enlarged image obtained by enlarging the left region of the crane vehicle  10 . 
     When the controller  60  determines that the operation signal indicating the enlargement of the image has not been input from the input device  49  (S 20 : No), the processing of step S 21  of generating the enlarged image is skipped. 
     The controller  60  displays the bird&#39;s-eye view image generated in step S 17 , the front image generated in step S 18 , the left image generated in step S 19 , or the enlarged image generated in step S 21  on the display  48  as an obstacle display image (S 22 ). 
     Subsequently, the controller  60  determines whether the operator has input an instruction to end the obstacle display mode by using the input device  49  (S 23 ). Specifically, the controller  60  determines whether an end signal has been input from the input device  49 . When the controller  60  determines that the end signal has not been input (S 23 : No), the controller  60  returns to the processing of step S 12  and continues the display processing. On the other hand, when the controller  60  determines that the end signal has been input (S 23 : Yes), the controller  60  ends the display processing. 
     Operation and Effect of the First Embodiment 
     In the present embodiment, an image ( FIG. 7 ) including the vehicle object and the obstacle object is displayed on the display  48 , so that the operator of the crane vehicle  10  can easily recognize the position of the obstacle with respect to the crane vehicle  10 . In addition, the distance between the vehicle object that represents the crane vehicle  10  and the obstacle object that represents the obstacle corresponds to the separation distance detected by the obstacle sensor  50 , so that the operator can easily recognize the distance from the crane vehicle  10  to the obstacle. 
     In addition, in the present embodiment, when the obstacle is far from the crane vehicle  10 , the color of the obstacle object is the first predetermined color (for example, blue), and when the obstacle is close to the crane vehicle  10 , the color of the obstacle object is the second predetermined color (for example, red), thus enabling the operator to instantly recognize whether the obstacle is close to the crane vehicle  10 . 
     Besides, in the present embodiment, when the obstacle approaches, the color of the obstacle object is changed from the first predetermined color (for example, blue) to the second predetermined color (for example, red), thus enabling the operator to instantly recognize that the obstacle is approaching. 
     In addition, in the present embodiment, the image selected by the operator from the “bird&#39;s-eye view image”, the “front image”, and the “left image” is displayed on the display  48 . Thus, an image that the operator feels easy to see can be displayed on the display. 
     Besides, in the present embodiment, when the operator inputs an enlargement instruction, the region on the left side of the crane vehicle  10 , which is a blind spot from the driver seat  41 , is enlarged and displayed on the display  48 . That is, the region which is a blind spot from the driver seat  41  is enlarged without prompting the operator to designate the region to be enlarged. Thus, the operation of the operator is facilitated. 
     Besides, in the present embodiment, the sound output from the speaker  68  also notifies that the obstacle is close to the crane vehicle  10 . Thus, the operator can more reliably recognize that the obstacle is close to the crane vehicle  10  or recognize that the obstacle is within the threshold distance. 
     In addition, in the present embodiment, because the obstacle is detected by radio waves, the obstacle can be reliably detected even when the surroundings are dark such as at night. That is, the obstacle is reliably displayed on the display  48  even when the surroundings are dark such as at night. 
     MODIFICATION EXAMPLE 1 
     In this modification example, an example is described in which the controller  60  determines whether the detected obstacle is a moving object that moves or a fixed object that does not move. 
     The crane vehicle  10  described in this modification example further includes the vehicle speed sensor  53  and the steering sensor  54  shown by broken lines in  FIG. 4 . The vehicle speed sensor  53  outputs, as a detection signal, pulses of the number (per unit time) in accordance with the vehicle speed of the crane vehicle  10 . The steering sensor  54  is, for example, a resolver or an encoder. The steering sensor  54  outputs a signal as a detection signal in accordance with the rotational position (steering angle) of the steering wheel  45 . The detection signals output by the vehicle speed sensor  53  and the steering sensor  54  are input to the controller  60 . The steering sensor  54  corresponds to the “second sensor” of the present invention. The vehicle speed sensor  53  corresponds to the “third sensor” of the present invention. 
     Display Processing 
     In this modification example, the controller  60  executes the display processing shown in  FIG. 8  instead of the display processing shown in  FIG. 5 . Moreover, in the display processing shown in  FIG. 8 , the same processing as the display processing shown in  FIG. 5  is denoted by the same reference characters and the description thereof is omitted. 
     The controller  60  executes the processing of steps S 11  to S 15  and S 24  as in the above embodiment (the display processing shown in  FIG. 5 ). Subsequently, the controller  60  executes an obstacle determination processing for determining whether the obstacle detected by the obstacle sensor  50  is a moving object or a fixed object (S 51 ). 
     Specifically, the controller  60  calculates the traveling direction and the vehicle speed (moving speed) of the crane vehicle  10  based on the detection signals input from the vehicle speed sensor  53  and the steering sensor  54 . The traveling direction of the crane vehicle  10  is, for example, straight travel, reverse travel, left turn, right turn, or the like. Next, the controller  60  calculates the moving direction and the moving speed of the detected obstacle based on the temporal change in the position of the obstacle detected in the obstacle detection processing (S 12 ). The controller  60  determines that the detected obstacle is a fixed object when the calculated traveling direction and vehicle speed (moving speed) of the crane vehicle  10  coincide with the calculated moving direction and moving speed of the obstacle. On the other hand, the controller  60  determines that the obstacle is a moving object when the calculated traveling direction and vehicle speed (moving speed) of the crane vehicle  10  do not coincide with the calculated moving direction and moving speed of the obstacle. Moreover, the “determination of whether the obstacle is a moving body or a fixed object” described above is an example only and may be performed by other methods. 
     In response to the determination that the detected obstacle is a moving object (S 51 : Yes), the controller  60  changes the second predetermined color (for example, yellow) set in step S 15  to a third predetermined color (for example, red) different from the second predetermined color and the first predetermined color (for example, blue) (S 52 ). In addition, in response to the determination that the detected obstacle is a moving object (S 51 : Yes), the controller  60  changes the first predetermined color (for example, blue) set in step S 14  to a fifth predetermined color (for example, orange) different from the first predetermined color, the second predetermined color, and the third predetermined color (S 52 ). The third predetermined color and the fifth predetermined color are colors previously stored in the memory  64 . On the other hand, the controller  60  skips the processing of step S 52  when the detected obstacle is not a moving object (that is, the detected obstacle is a fixed object) (S 51 : No). 
     After executing step S 52 , the controller  60  executes the processing of steps S 16  to S 23  as in the embodiment described above, and ends the display processing. 
     Operation and Effect of Modification Example 1 
     In this modification example, a fixed object such as a wall of a building and a moving object such as a pedestrian, a motorcycle, or a bicycle are displayed with colors changed, thus enabling the user to instantly recognize whether the object is a fixed object or a moving object. 
     In addition, when the distance from the crane vehicle  10  to the obstacle is short and the obstacle is a moving object, the color of the obstacle object is changed from the second predetermined color (for example, yellow) to the third predetermined color (for example, yellow), thus enabling the user to easily recognize that more attention is required. 
     MODIFICATION EXAMPLE 2 
     In this modification example, an example is described in which the obstacle sensor  50 A is used to detect obstacles around a load suspended by the hook  35  or a distance to the suspended load during the operation of the crane device  12 . 
     The configuration of a crane vehicle  70  shown in  FIG. 9  is the same as the configuration of the crane vehicle  10  described in the first embodiment, except that the crane vehicle  70  has a rotating body that changes the orientation of the antenna of the obstacle sensor  50 A. 
     The input device  49  receives an instruction to select an obstacle detection mode for detecting obstacles around the load  71  during the operation of the crane device  12 . 
     Hereinafter, the display processing executed by the controller  60  during the operation of the crane device  12  is described with reference to  FIG. 10 . The display processing is processing in which the presence/absence of obstacles around the load  71 , the distance from the front end of the boom  32  to the load  71 , or the like is displayed on a state display image showing the swiveling angle of the swivel base  31 , the derricking angle of the boom  32 , the length of the boom  32 , and the like. 
     First, the controller  60  determines whether the operator has selected the obstacle detection mode by using the input device  49  (S 41 ). Specifically, the controller  60  determines whether a start signal has been input from the input device  49 . That is, the display processing is started when the operator has selected the obstacle display mode. 
     The controller  60  waits until a start signal is input (S 41 : No). When the controller  60  determines that the start signal has been input (S 41 : Yes), the controller  60  changes the orientation of the obstacle sensor  50 A (S 42 ). Specifically, the orientation of the obstacle sensor  50 A is changed to the orientation in which the detection wave is irradiated toward the underneath of the front end of the boom  32 . 
     Subsequently, the controller  60  executes obstacle detection processing (S 43 ). Specifically, the controller  60  outputs a control signal to the transmission/reception circuit  66  and receives a detection signal as in the processing of step S 31  ( FIG. 6 ). The controller  60  determines whether an obstacle exists around the load  71  based on the received detection signal (S 44 ). 
     When the controller  60  determines that an obstacle exists around the load  71  (S 44 : Yes), the controller  60  causes the display  48  to display an image indicating that an obstacle exists around the load  71 , or causes the speaker  68  to output a warning sound (S 45 ). Moreover, whether the object is the load  71  or the obstacle is determined by, for example, the position of the detected object. For example, the controller  60  determines that the object located directly under the hook  35  is a “load” and the object existing around the “load” is an “obstacle”. 
     Subsequently, the controller  60  determines whether the operator has input an instruction to end the obstacle detection mode by using the input device  49  (S 48 ). Specifically, the controller  60  determines whether an end signal has been input from the input device  49 . When the controller  60  determines that the end signal has not been input (S 48 : No), the controller  60  returns to the processing of step S 42  and continues the display processing. On the other hand, when the controller  60  determines that the end signal has been input (S 48 : Yes), the controller  60  ends the display processing. 
     When the controller  60  determines that no obstacle exists in the processing of step S 44  (S 44 : No), the controller  60  calculates a suspension distance being the distance to the load  71  (S 46 ). The suspension distance is calculated from, for example, the time starting from the irradiation of the detection wave to the reception of the reflected wave reflected by the load  71 . 
     The controller  60  displays the calculated suspension distance on the state display image showing the swiveling angle of the swivel base  31 , the derricking angle of the boom  32 , the length of the boom  32 , and the like (S 47 ). Subsequently, the controller  60  determines whether the end signal has been input from the input device  49  (S 48 ). When the controller  60  determines that the end signal has not been input (S 48 : No), the controller  60  returns to the processing of step S 42  and continues the display processing. On the other hand, when the controller  60  determines that the end signal has been input (S 48 : Yes), the controller  60  ends the display processing. 
     Operation and Effect of Modification Example 2 
     In this modification example, the obstacle sensor  50 A arranged at the front end of the boom  32  can be used to detect the distance to the load  71  suspended by the crane device. In addition, an obstacle around the load  71  can be detected. 
     MODIFICATION EXAMPLE 3 
     In this modification example, an example is described in which infrared sensors  52  for detecting infrared rays is arranged in addition to the obstacle sensor  50 . 
     The infrared sensors  52  are arranged adjacent to the obstacle sensors  50 A,  50 B and  50 C, respectively. That is, three infrared sensors  52  are arranged on the crane vehicle  10 . The infrared sensor  52  corresponds to the “fourth sensor” of the present invention. 
     The infrared sensor  52  includes a lens for collecting incident infrared rays, a light receiving unit for receiving the infrared rays collected by the lens, and an amplifier circuit for amplifying and outputting a signal corresponding to the infrared rays received by the light receiving unit. The amplifier circuit is driven by the direct-current voltage supplied from the power supply circuit  65 . That is, the infrared sensor  52  is arranged adjacent to the obstacle sensor  50 , and thereby the power is supplied through the cable or the swivel connecting the obstacle sensor  50  and the control substrate. 
     A receiving unit may output a signal corresponding to the intensity of the received infrared ray, or may have a plurality of light receiving units. The infrared sensor  52  having a plurality of light receiving units outputs a signal corresponding to the difference in the intensity of the infrared rays received by each light receiving unit. That is, when an object to be detected such as a person who emits infrared rays moves, the infrared sensor  52  outputs a detection signal indicating that the object to be detected has been detected. 
     The region where the lens of the infrared sensor  52  performs light collection corresponds to the directional region of the obstacle sensor  50  being an antenna. That is, the lens of the infrared sensor  52  collects the infrared rays that are incident from the region where the obstacle sensor  50  mainly irradiates the detection wave. Therefore, the infrared sensor  52  detects the same region as the detection region of the obstacle sensor  50 . 
     Display Processing 
     In this modification example, the controller  60  executes the display processing shown in  FIG. 11  instead of the display processing shown in  FIG. 5 . Moreover, in the display processing shown in  FIG. 11 , the same processing as the display processing shown in  FIG. 5  is denoted by the same reference characters and the description thereof is omitted. 
     The controller  60  executes the processing of steps S 11  to S 15  and S 24  as in the first embodiment (display processing shown in  FIG. 5 ). Subsequently, the controller  60  determines whether the obstacle detected by the obstacle sensor  50  is a “person” (S 61 ). Specifically, the controller  60  calculates the position of the object to be detected that emits infrared rays in the same manner as in the first embodiment, based on the detection signals input from the plurality of infrared sensors  52 . The controller  60  determines whether the calculated position of the object to be detected matches the position of the obstacle. Subsequently, the controller  60  determines whether the size of the obstacle detected by the obstacle sensor  50  is equal to or larger than the threshold value. The threshold value is previously stored in the memory  64 . The controller  60  determines that the obstacle is a “person” when the position of the object to be detected matches the position of the obstacle and the size of the obstacle is equal to or larger than the threshold value. Moreover, the above-mentioned “determination of whether the obstacle is a person or not” is an example only and may be performed by other methods. 
     When the controller  60  determines that the detected obstacle is a person (S 61 : Yes), the controller  60  changes the second predetermined color (for example, yellow) set in step S 15  to the fourth predetermined color (for example, red) different from the second predetermined color, and changes the first predetermined color (for example, blue) set in step S 14  to a sixth predetermined color (for example, orange) different from the second predetermined color, the first predetermined color (for example, blue), and the fourth predetermined color (S 62 ). 
     On the other hand, when the controller  60  determines that the detected obstacle is not a person (S 61 : No), the controller  60  skips the processing of step S 62 . Then, the controller  60  executes the processing of steps S 16  to S 23  as in the first embodiment. 
     Operation and Effect of Modification Example 3 
     In this modification example, the color of the obstacle object is varied depending on whether the obstacle is a person or not, thus enabling the user to easily recognize whether the obstacle is a person or not. 
     In addition, when the distance from the crane vehicle  10  to the obstacle is short and the obstacle is a person, the color of the obstacle object is changed from the second predetermined color (for example, yellow) to the fourth predetermined color (for example, red), thus enabling the operator to easily recognize that more attention is required. 
     Moreover, the configuration of this modification example may be added to Modification example 1. In that case, the fourth predetermined color is different from the second predetermined color and the third predetermined color, and the sixth predetermined color is different from the fifth predetermined color. 
     MODIFICATION EXAMPLE 4 
     As shown in  FIG. 12 , the crane vehicle  10  of this modification example includes a plurality of (four in the illustrated example) cameras  55 . The first camera  55  is arranged in the front part of the crane vehicle  10  to capture images in front of the crane vehicle  10 . The second camera  55  is arranged at the rear side of the crane vehicle  10  to capture images back of the crane vehicle  10 . The third camera  55  is arranged on the left side of the crane vehicle  10  to capture images on the left side of the crane vehicle  10 . The fourth camera  55  is arranged on the right side of the crane vehicle  10  to capture images on the right side of the crane vehicle  10 . 
     The camera  55  is electrically connected to the control substrate through a cable or a swivel. The camera  55  outputs the captured image as an image signal. The image signal output by the camera  55  is input to the controller  60 . The controller  60  synthesizes a plurality of images represented by the input image signals to generate a bird&#39;s-eye view image of the periphery of the crane vehicle  10 . Because the method by which the controller  60  generates a bird&#39;s-eye view image from a plurality of images is publicly known, detailed description thereof is omitted. 
     The controller  60  synthesizes the generated bird&#39;s-eye view images of the periphery of the crane vehicle  10  into the bird&#39;s-eye view image described in the embodiment, and displays the synthesized image on the display  48  as an obstacle display image. Alternatively, the controller  60  synthesizes the images captured by the camera  55  for capturing images in front of the crane vehicle  10  into the front image described in the embodiment, and displays the front image on the display  48  as an obstacle display image. Alternatively, the controller  60  synthesizes the images captured by the camera  55  for capturing images on the left side of the crane vehicle  10  into the left image described in the embodiment, and displays the left image on the display  48  as an obstacle display image. 
     Operation and Effect of Modification Example 4 
     In this modification example, in addition to the vehicle object and the obstacle object, the image of the periphery of the crane vehicle  10  is also added to the obstacle display image, thus enabling the operator to recognize the situation around the crane vehicle  10  more easily. 
     Other Modification Examples 
     In the above embodiment, an example is described in which no obstacle sensor  50  is arranged on the right side of the swivel base  31  on which the cabin  13  is arranged. However, the obstacle sensor  50  may also be arranged on the right side of the swivel base  31 . 
     In addition, in the above-described embodiment, an example is described in which the boom  32  is located on the left side of the swivel base  31  and the cabin  13  is located on the right side of the swivel base  31 . However, the boom  32  may also be located on the right side of the swivel base  31  and the cabin  13  may also be located on the left side of the swivel base  31 . 
     Besides, in the above-described embodiment and modification examples, an example is described in which the user selects whether to execute the obstacle detection mode. However, the obstacle detection mode may always be executed. 
     In addition, in the above-described embodiment, an example is described in which the transmission/reception circuit  66  is mounted on the control substrate, the obstacle sensor  50  being an antenna is arranged on the boom  32  or the vehicle body  20 , and the transmission/reception circuit  66  is electrically connected to the obstacle sensor  50  through a cable or a swivel. However, a transmission/reception module in which an antenna and the transmission/reception circuit  66  are integrated may also be used instead of the obstacle sensor  50  and the transmission/reception circuit  66 . 
     Furthermore, in the above-described embodiment, an example is described in which the obstacle sensor  50  transmits the detection wave by the power supplied from the power supply circuit  65  arranged in the cabin  13 . However, an antenna power supply circuit for supplying power to the obstacle sensor  50  may also be arranged in the vehicle body  20  separately from the power supply circuit  65 . The antenna power supply circuit transforms the direct-current voltage supplied from the battery  27  into a predetermined direct-current voltage and outputs the direct-current voltage. 
     In addition, in the above-described embodiment, an example is described in which a signal corresponding to the reflected wave received by the obstacle sensor  50  is input to the controller  60  through a cable or a swivel. However, the obstacle sensor  50  and the controller  60  may be configured to be capable of wirelessly communicating with each other, and a signal corresponding to the reflected wave received by the obstacle sensor  50  may be input to the controller  60  by wireless communication. Specifically, the obstacle sensor  50  has a transmission antenna for wireless communication. A reception antenna (pattern antenna) for wireless communication is arranged in the control substrate. The signal output from the obstacle sensor  50  is input to the controller  60  by wireless communication, and thus noise can be prevented from being superimposed on the signal at the swivel. 
     Besides, in Modification example 4 described above, an example is described in which the image signal output by the camera  55  is input to the controller  60  through a cable or a swivel. However, the camera  55  and the controller  60  may be configured to be capable of wirelessly communicating with each other, and the image signal output by the camera  55  may be input to the controller  60  by wireless communication. Specifically, the camera  55  is electrically connected to the transmission antenna for wireless communication through a cable. A reception antenna (a pattern antenna or the like) for wireless communication is arranged in the control substrate. The image signal output by the camera  55  is input to the controller  60  by wireless communication. Thus, noise can be prevented from being superimposed on the image signal at the swivel. 
     Furthermore, in the above-described embodiment, the obstacle sensor  50  that transmits radio waves has been described. However, the obstacle sensor  50  may also irradiate light such as laser light. In that case, the obstacle sensor  50  includes a light emitting unit such as a light emitting diode for irradiating light, a light receiving unit such as a photodiode for receiving the light and outputting a voltage corresponding to the intensity of the received light, and an amplification unit for amplifying the voltage output by the light receiving unit and outputting the amplified voltage as a detection signal. 
     In addition, in the above-described embodiment, the obstacle sensor  50  that transmits radio waves has been described. However, the obstacle sensor  50  may also irradiate sound waves (including ultrasonic waves). In that case, an (ultra) ultrasonic wave sensor, a Doppler sensor, or the like is used as the obstacle sensor  50 . Moreover, when an obstacle is detected by sound waves, a temperature sensor for temperature compensation such as a thermistor for detecting the outside air temperature is arranged on the crane vehicle  10 .