Carrier

Abstract

To provide a technique which improves safety property when a dolly operates in an automatic mode.SOLUTION: A dolly may comprise: drive wheels; motors which rotate the drive wheels, respectively; motor drive circuits which are configured to drive the motors, respectively; control units which are configured to control the motors through the motor drive circuits, respectively so that advance speed of the dolly is an upper limit advance speed or less; and an operation member which is arranged in the dolly and receives operation performed by a user. The dolly may be operable in either of a manual mode, in which when the operation member is ON, the motor of the dolly drives, and when the operation member is OFF, the motor does not drive; and an automatic mode, in which the motor drives regardless of ON / OFF of the operation member. The upper limit advance speed in the automatic mode may be set to be lower than the upper limit advance speed in a manual mode.SELECTED DRAWING: Figure 37

Description

Technical Field

[0001] The technology disclosed in this specification relates to a transport vehicle.

Background Art

[0002] Patent Document 1 discloses a transport vehicle. The transport vehicle includes a drive wheel, a motor that rotates the drive wheel, a motor drive circuit configured to drive the motor, a control unit that controls the motor via the motor drive circuit so that the traveling speed of the transport vehicle is equal to or lower than an upper limit traveling speed, and an operation member provided on the transport vehicle that receives an operation by a user. The transport vehicle can operate in a manual mode in which the motor is driven when the operation member is on and the motor stops when the operation member is off, and an automatic mode in which the motor is driven regardless of whether the operation member is on or off.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When the transport vehicle operates in the automatic mode, a higher level of safety is required compared to when the transport vehicle operates in the manual mode. This specification provides a technology capable of further enhancing the safety when the transport vehicle operates in the automatic mode.

Means for Solving the Problems

[0005] The carrier vehicle disclosed in this specification includes a drive wheel, a motor that rotates the drive wheel, a motor drive circuit configured to drive the motor, a control unit configured to control the motor via the motor drive circuit such that the traveling speed of the carrier vehicle is equal to or lower than the upper limit traveling speed, and an operation member provided on the carrier vehicle and configured to receive an operation by a user. The carrier vehicle may operate in a manual mode in which the motor is driven when the operation member is on and the motor stops when the operation member is off, and an automatic mode in which the motor is driven regardless of whether the operation member is on or off. The upper limit traveling speed in the automatic mode may be set lower than the upper limit traveling speed in the manual mode.

[0006] According to the above configuration, since the upper limit traveling speed when the carrier vehicle operates in the automatic mode is set lower than the upper limit traveling speed when the carrier vehicle operates in the manual mode, the safety when the carrier vehicle operates in the automatic mode can be further enhanced.

Brief Description of the Drawings

[0007]

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Mode for Carrying Out the Invention

[0008] Hereinafter, representative and non-limiting specific examples of the present invention will be described in detail with reference to the drawings. This detailed description is simply intended to show those skilled in the art the details for implementing the preferred examples of the present invention and is not intended to limit the scope of the present invention. Also, the additional features and inventions disclosed below can be used separately or together with other features and inventions in order to provide a further improved carrier vehicle, its manufacturing method, and its usage method.

[0009] Also, the combinations of features and steps disclosed in the following detailed description are not essential for carrying out the present invention in the broadest sense, and are described only for the purpose of explaining typical specific examples of the present invention in particular. Further, the various features of the above and below typical specific examples, as well as the various features described in the independent and dependent claims, do not have to be combined as described in the specific examples here or in the order listed, in providing additional and useful embodiments of the present invention.

[0010] All features described in this specification and / or the claims are intended to be disclosed separately and independently of each other, as limitations to the initial disclosure and the claimed specific matters, apart from the configurations of the features described in the examples and / or claims. Further, all descriptions regarding numerical ranges and groups or populations are made with the intention of disclosing intermediate configurations as limitations to the initial disclosure and the claimed specific matters.

[0011] In one or more embodiments, the carrier vehicle may include drive wheels, a motor that rotates the drive wheels, a motor drive circuit configured to drive the motor, a control unit configured to control the motor via the motor drive circuit such that the traveling speed of the carrier vehicle is equal to or lower than an upper limit traveling speed, and an operation member provided on the carrier vehicle and configured to receive an operation by a user. The carrier vehicle may operate in a manual mode in which the motor is driven when the operation member is on and the motor stops when the operation member is off, and an automatic mode in which the motor is driven regardless of the on / off state of the operation member. The upper limit traveling speed in the automatic mode may be set lower than the upper limit traveling speed in the manual mode.

[0012] According to the above configuration, since the upper limit traveling speed when the carrier operates in the automatic mode is set lower than the upper limit traveling speed when the carrier operates in the manual mode, the safety when the carrier operates in the automatic mode can be further enhanced.

[0013] In one or more embodiments, the carrier may further include an overload detection sensor for detecting overloading of the load. In the automatic mode, when overloading is detected by the overload detection sensor, the running of the carrier may be prohibited. In the manual mode, even if overloading is detected by the overload detection sensor, the running of the carrier may be permitted.

[0014] According to the above configuration, in the manual mode, the running of the carrier is permitted even if overloading is detected, and in the automatic mode, the running of the carrier is prohibited when overloading is detected. Therefore, the safety when the carrier operates in the automatic mode can be further enhanced.

[0015] In one or more embodiments, the carrier may further include a collision detection sensor for detecting a collision from the front to the carrier. In the automatic mode, when the carrier is moving backward and a collision is detected by the collision detection sensor, the running of the carrier may be prohibited. In the manual mode, when the carrier is moving backward and a collision is detected by the collision detection sensor, the running of the carrier may be permitted.

[0016] According to the above configuration, in the manual mode, the running of the carrier is permitted even if a collision from the front of the carrier is detected when the carrier is moving backward, and in the automatic mode, the running of the carrier is prohibited when a collision from the front of the carrier is detected when the carrier is moving backward. Therefore, the safety when the carrier operates in the automatic mode can be further enhanced.

[0017] In one or more embodiments, the carrier vehicle may further include a collision detection sensor that detects a rear collision to the carrier vehicle. In the automatic mode, when the carrier vehicle is moving forward and a collision is detected by the collision detection sensor, the running of the carrier vehicle may be prohibited. In the manual mode, when the carrier vehicle is moving forward and a collision is detected by the collision detection sensor, the running of the carrier vehicle may be permitted.

[0018] According to the above configuration, in the manual mode, the running of the carrier vehicle is permitted even when a rear collision to the carrier vehicle is detected while the carrier vehicle is moving forward, and in the automatic mode, the running of the carrier vehicle is prohibited when a rear collision to the carrier vehicle is detected while the carrier vehicle is moving forward. Therefore, the safety when the carrier vehicle operates in the automatic mode can be further enhanced.

[0019] In one or more embodiments, the carrier vehicle may be capable of performing a follow-up operation of moving by tracking a beacon carried by a user and a remote control operation of moving according to an instruction from a remote control operated by the user in the automatic mode.

[0020] According to the above configuration, the safety when the carrier vehicle performs a follow-up operation or a remote control operation in the automatic mode can be further enhanced.

[0021] (Example) The carrier 2 shown in FIG. 1 includes a chassis unit 4, a loading platform unit 6, a handle unit 8, a steering unit 10, a front wheel unit 12, a rear wheel unit 14, and a bumper unit 16. The carrier 2 transports the goods loaded on the loading platform unit 6. The carrier 2 includes a receiver (not shown) mounted on the chassis unit 4. The carrier 2 can operate in any of a manual mode, an automatic mode, or a parking mode. In the manual mode, the carrier 2 moves forward or backward according to the operation of the user while the user standing behind the handle unit 8 holds the handle unit 8. In the automatic mode, the carrier 2 performs a follow-up operation of tracking a beacon (not shown) carried by the user standing in front of the chassis unit 4 and a remote control operation of moving according to an instruction from a remote control (not shown) operated by the user. In this case, the carrier 2 receives radio waves from the beacon or the remote control by the receiver. In the parking mode, the carrier 2 locks the rear wheel unit 14 and continues to stop on the spot.

[0022] (Chassis unit 4) As shown in FIGS. 2 and 3, the chassis unit 4 includes a base plate 20, a front support member 22, a rear support member 24, a lower right frame 26, a lower left frame 28, an upper right frame 30, an upper left frame 32, a battery box 34, an overloading detection mechanism 302, an emergency stop switch case 304, an upper controller case 306, and a lower controller case 36. The overloading detection mechanism 302 includes a right front overloading detection mechanism 302a, a left front overloading detection mechanism 302b, a right rear overloading detection mechanism 302c, and a left rear overloading detection mechanism 302d.

[0023] As shown in FIG. 2, the base plate 20 is a member made of aluminum, and has a substantially rectangular flat plate shape with its longitudinal direction along the front-rear direction and its short-side direction along the left-right direction. The emergency stop switch case 304 is a member made of resin, and is fixed to the lower surface of the base plate 20 at the front end of the base plate 20. An emergency stop switch 308 that can be pressed by the user is provided on the front surface of the emergency stop switch case 304. The emergency stop switch 308 is normally off and turns on when pressed by the user. The emergency stop switch 308 is electrically connected to a main control circuit board 44 described later. Note that the emergency stop switch case 304 may be provided at the rear end, right end, or left end of the base plate 20, and accordingly, the emergency stop switch 308 may be provided on the rear surface, right surface, or left surface of the emergency stop switch case 304.

[0024] The front support member 22 is a member made of steel, and is attached to the lower surface of the base plate 20 at the front portion of the base plate 20 via a right front overload detection mechanism 302a and a left front overload detection mechanism 302b. As shown in FIG. 3, the rear support member 24 is a member made of steel, and is attached to the lower surface of the base plate 20 at the rear portion of the base plate 20 via a right rear overload detection mechanism 302c and a left rear overload detection mechanism 302d. The lower right frame 26 and the lower left frame 28 are both members made of steel, extend in the front-rear direction below the base plate 20. The front portion of the lower right frame 26 and the front portion of the lower left frame 28 are respectively fixed to the front support member 22. The rear portion of the lower right frame 26 and the rear portion of the lower left frame 28 are respectively fixed to the rear support member 24.

[0025] The right front overloading detection mechanism 302a, the left front overloading detection mechanism 302b, the right rear overloading detection mechanism 302c, and the left rear overloading detection mechanism 302d all have the same configuration. As shown in FIG. 4, the right front overloading detection mechanism 302a, the left front overloading detection mechanism 302b, the right rear overloading detection mechanism 302c, and the left rear overloading detection mechanism 302d all include pillar members 312a, 312b, 312c, 312d, coil springs 314a, 314b, 314c, 314d, detection plates 316a, 316b, 316c, 316d, base members 318a, 318b, 318c, 318d, and overloading detection sensors 320a, 320b, 320c, 320d. As shown in FIG. 5, the pillar members 312a, 312b, 312c, 312d include cylindrical portions 322a, 322b, 322c, 322d, flange portions 324a, 324b, 324c, 324d, upper small-diameter portions 326a, 326b, 326c, 326d, and lower small-diameter portions 328a, 328b, 328c, 328d. The cylindrical portions 322a, 322b, 322c, 322d have a substantially cylindrical shape with the axial direction along the vertical direction. The flange portions 324a, 324b, 324c, 324d are arranged above the cylindrical portions 322a, 322b, 322c, 322d and have a shape protruding radially outward from the cylindrical portions 322a, 322b, 322c, 322d. The upper small-diameter portions 326a, 326b, 326c, 326d are arranged above the flange portions 324a, 324b, 324c, 324d and have a substantially cylindrical shape with a smaller diameter than the cylindrical portions 322a, 322b, 322c, 322d. The lower small-diameter portions 328a, 328b, 328c, 328d are arranged below the cylindrical portions 322a, 322b, 322c, 322d and have a substantially cylindrical shape with a smaller diameter than the cylindrical portions 322a, 322b, 322c, 322d.

[0026] The upper small-diameter portions 326a, 326b, 326c, and 326d are inserted downward into through-holes 330a, 330b, 330c, and 330d formed in the base plate 20. Threaded holes 332a, 332b, 332c, and 332d are formed at the upper ends of the pillar members 312a, 312b, 312c, and 312d. Bolts 336a, 336b, 336c, and 336d are screwed into the threaded holes 332a, 332b, 332c, and 332d via washers 334a, 334b, 334c, and 334d. When the bolts 336a, 336b, 336c, and 336d are screwed into the threaded holes 332a, 332b, 332c, and 332d, the base plate 20 is clamped by the washers 334a, 334b, 334c, and 334d and the flange portions 324a, 324b, 324c, and 324d. Since the inner diameters of the through-holes 20a, 20b, 20c, and 20d are slightly larger than the outer diameters of the upper small-diameter portions 326a, 326b, 326c, and 326d, the pillar members 312a, 312b, 312c, and 312d can tilt slightly with respect to the base plate 20.

[0027] The lower small-diameter portions 328a, 328b, 328c, 328d are inserted from above into through-holes 338a, 338b, 338c, 338d formed in the front support member 22 (or the rear support member 24). Since the inner diameters of the through-holes 338a, 338b, 338c, 338d are slightly larger than the outer diameters of the lower small-diameter portions 328a, 328b, 328c, 328d, the pillar members 312a, 312b, 312c, 312d can tilt slightly with respect to the front support member 22 (or the rear support member 24). Coil springs 314a, 314b, 314c, 314d are attached to the pillar members 312a, 312b, 312c, 312d. The upper ends of the coil springs 314a, 314b, 314c, 314d are in contact with the lower surfaces of washers 340a, 340b, 340c, 340d. The upper surfaces of the washers 340a, 340b, 340c, 340d are in contact with the lower surfaces of flange portions 324a, 324b, 324c, 324d. The lower ends of the coil springs 314a, 314b, 314c, 314d are in contact with the upper surfaces of the front support member 22 (or the rear support member 24). The coil springs 314a, 314b, 314c, 314d bias the pillar members 312a, 312b, 312c, 312d upward with respect to the front support member 22 (or the rear support member 24).

[0028] Threaded holes 342a, 342b, 342c, 342d are formed at the lower ends of the pillar members 312a, 312b, 312c, 312d. Bolts 344a, 344b, 344c, 344d are screwed into the threaded holes 342a, 342b, 342c, 342d via detection plates 316a, 316b, 316c, 316d. The detection plates 316a, 316b, 316c, 316d include support portions 346a, 346b, 346c, 346d having a substantially flat plate shape along the front-rear direction and the left-right direction, and detection portions 348a, 348b, 348c, 348d that are bent downward from the ends of the support portions 346a, 346b, 346c, 346d and have a substantially flat plate shape along the front-rear direction and the up-down direction.

[0029] The base members 318a, 318b, 318c, 318d include engaging portions 350a, 350b, 350c, 350d, nut portions 352a, 352b, 352c, 352d, guide portions 354a, 354b, 354c, 354d, and sensor holding portions 356a, 356b, 356c, 356d. The engaging portions 350a, 350b, 350c, 350d can be engaged with the front support member 22 (or the rear support member 24). Bolts 358a, 358b, 358c, 358d are screwed into the nut portions 352a, 352b, 352c, 352d. The lower ends of the bolts 358a, 358b, 358c, 358d penetrate the nut portions 352a, 352b, 352c, 352d and abut against the upper surface of the front support member 22 (or the rear support member 24). The base members 318a, 318b, 318c, 318d are fixed to the front support member 22 (or the rear support member 24) by tightening the bolts 358a, 358b, 358c, 358d against the nut portions 352a, 352b, 352c, 352d with the engaging portions 350a, 350b, 350c, 350d engaged with the front support member 22 (or the rear support member 24). The guide portions 354a, 354b, 354c, 354d have a shape that guides the vertical movement of the detection plates 316a, 316b, 316c, 316d. Overload detection sensors 320a, 320b, 320c, 320d are attached to the sensor holding portions 356a, 356b, 356c, 356d. The vertical mounting positions of the overload detection sensors 320a, 320b, 320c, 320d with respect to the sensor holding portions 356a, 356b, 356c, 356d are adjustable.

[0030] The overload detection sensors 320a, 320b, 320c, 320d of this embodiment are so-called photo-interrupters. The overload detection sensors 320a, 320b, 320c, 320d include light-emitting elements 360a, 360b, 360c, 360d and light-receiving elements 362a, 362b, 362c, 362d arranged to face each other. The overload detection sensors 320a, 320b, 320c, 320d turn off when there is no obstruction between the light-emitting elements 360a, 360b, 360c, 360d and the light-receiving elements 362a, 362b, 362c, 362d, and turn on when there is an obstruction therebetween. The overload detection sensors 320a, 320b, 320c, 320d are electrically connected to a main control circuit board 44 (see FIG. 9) described later.

[0031] As shown in FIG. 5, when no load is placed on the loading platform unit 6 and no load from the loading platform unit 6 acts on the base plate 20, the upper surfaces of the support portions 346a, 346b, 346c, 346d of the detection plates 316a, 316b, 316c, 316d abut against the lower surface of the front support member 22 (or the rear support member 24) due to the biasing force of the coil springs 314a, 314b, 314c, 314d. In this state, since the detection portions 348a, 348b, 348c, 348d of the detection plates 316a, 316b, 316c, 316d do not obstruct the space between the light-emitting elements 360a, 360b, 360c, 360d and the light-receiving elements 362a, 362b, 362c, 362d, the overload detection sensors 320a, 320b, 320c, 320d are turned off.

[0032] From the state shown in FIG. 5, when a load is placed on the loading platform unit 6 and a load from the loading platform unit 6 acts on the base plate 20, against the biasing forces of the coil springs 314a, 314b, 314c, 314d, the pillar members 312a, 312b, 312c, 312d and the detection plates 316a, 316b, 316c, 316d move downward with respect to the front support member 22 (or the rear support member 24). At this time, when a load of a predetermined upper limit load (for example, 25 kgf) or more acts on the pillar members 312a, 312b, 312c, 312d, as shown in FIG. 6, the detection plates 316a, 316b, 316c, 316d block the light between the light emitting elements 360a, 360b, 360c, 360d and the light receiving elements 362a, 362b, 362c, 362d, and the overload detection sensors 320a, 320b, 320c, 320d switch from off to on. Note that the pillar members 312a, 312b, 312c, 312d and the detection plates 316a, 316b, 316c, 316d are movable downward with respect to the base plate 20 until the lower surfaces of the cylindrical portions 322a, 322b, 322c, 322d contact the upper surface of the base plate 20. By adopting such a configuration, the overload detection mechanism 302 can detect an overload on the loading platform unit 6. For example, when the upper limit load of each of the right front overload detection mechanism 302a, the left front overload detection mechanism 302b, the right rear overload detection mechanism 302c, and the left rear overload detection mechanism 302d is 25 kgf, the overload detection mechanism 302 detects an overload on the loading platform unit 6 when a load exceeding 100 kg is placed on the loading platform unit 6.

[0033] As described above, all of the overload detection sensors 320a, 320b, 320c, 320d are non-contact detection sensors. Therefore, it is possible to suppress the vibration and impact from the loading platform unit 6 from being transmitted to the overload detection sensors 320a, 320b, 320c, 320d and causing the overload detection sensors 320a, 320b, 320c, 320d to malfunction.

[0034] Note that the overloading detection mechanism 364 shown in FIG. 7 may be used as the right front overloading detection mechanism 302a, the left front overloading detection mechanism 302b, the right rear overloading detection mechanism 302c, and the left rear overloading detection mechanism 302d. The overloading detection mechanism 364 includes a support member 366, a pillar member 368, a coil spring 370, a detection plate 372, an upper housing 374, a sensor holding member 376, a lower housing 378, an overloading detection sensor 380, and a cap 382.

[0035] The support member 366 is fixed to the lower surface of the base plate 20. The pillar member 368 includes a cylindrical portion 384, an upper small-diameter portion 386, and a lower small-diameter portion 388. The cylindrical portion 384 has a substantially cylindrical shape with its axial direction along the vertical direction. The upper small-diameter portion 386 is disposed above the cylindrical portion 384 and has a substantially cylindrical shape with a smaller diameter than the cylindrical portion 384. The lower small-diameter portion 388 is disposed below the cylindrical portion 384 and has a substantially cylindrical shape with a smaller diameter than the cylindrical portion 384. The upper small-diameter portion 386 is inserted downward into a through hole 390 formed in the support member 366. A screw hole 392 is formed at the upper end of the pillar member 368. A bolt 398 is screwed into the screw hole 392 via washers 394 and 396. In a state where the bolt 398 is screwed into the screw hole 392, the support member 366 is clamped by the washer 396 and the cylindrical portion 384. Since the inner diameter of the through hole 390 is slightly larger than the outer diameter of the upper small-diameter portion 386, the pillar member 368 can be slightly tilted with respect to the support member 366.

[0036] The lower small-diameter portion 388 and the cylindrical portion 384 are inserted into the accommodation chamber 400 formed in the upper housing 374 from above. The lower small-diameter portion 388 is inserted into the through-hole 404 formed in the bottom wall 402 of the accommodation chamber 400 from above. Since the inner diameter of the through-hole 404 is slightly larger than the outer diameter of the lower small-diameter portion 388, the pillar member 368 can tilt slightly with respect to the upper housing 374. A coil spring 370 is attached to the pillar member 368. The upper end of the coil spring 370 abuts against the lower surface of the cylindrical portion 384. The lower end of the coil spring 370 abuts against the upper surface of the bottom wall 402. The coil spring 370 biases the pillar member 368 upward with respect to the upper housing 374. The inner diameter of the accommodation chamber 400 is slightly larger than the outer diameter of the cylindrical portion 384. Near the upper end of the accommodation chamber 400, a seal member 406 that slidably abuts against the side surface of the cylindrical portion 384 is provided. The seal member 406 is, for example, a resin O-ring. The seal member 406 suppresses the intrusion of foreign matter into the interior of the accommodation chamber 400. Further, an annular cushion 408 is provided at the upper end of the upper housing 374.

[0037] A screw hole 410 is formed at the lower end of the pillar member 368. A bolt 412 is screwed into the screw hole 410 via a detection plate 372. The detection plate 372 includes a support portion 414 having a substantially flat plate shape along the front-rear direction and the left-right direction, and a detection portion 416 that bends downward from an end of the support portion 414 and has a substantially flat plate shape along the front-rear direction and the up-down direction. A guide portion 418 for guiding the vertical movement of the detection plate 372 is formed at the lower part of the upper housing 374.

[0038] At the lower end of the upper housing 374, a sensor holding member 376 is fixed. An overload detection sensor 380 is attached to the sensor holding member 376. The overload detection sensor 380 of this embodiment is a so-called photointerrupter. The overload detection sensor 380 includes a light emitting element 420 and a light receiving element 422 arranged to face each other. The overload detection sensor 380 is turned off when the space between the light emitting element 420 and the light receiving element 422 is not blocked, and is turned on when the space between the light emitting element 420 and the light receiving element 422 is blocked. The overload detection sensor 380 is electrically connected to a main control circuit board 44 (see FIG. 9) described later.

[0039] In the lower housing 378, a housing space 424 penetrating the lower housing 378 from above to below is formed. The lower part of the upper housing 374 is inserted into the housing space 424 of the lower housing 378 from above. The detection plate 372, the sensor holding member 376, and the overload detection sensor 380 are housed in the housing space 424. The lower housing 378 is fixed to the front support member 22 (or the rear support member 24) together with the upper housing 374. A cap 382 is detachably attached to the lower end of the lower housing 378.

[0040] As shown in FIG. 7, when no load is placed on the loading platform unit 6 and no load from the loading platform unit 6 acts on the base plate 20, due to the biasing force of the coil spring 370, the upper surface of the support portion 414 of the detection plate 372 abuts against the lower surface of the bottom wall 402 of the upper housing 374. In this state, since the detection portion 416 of the detection plate 372 does not block the space between the light emitting element 420 and the light receiving element 422, the overload detection sensor 380 is turned off.

[0041] From the state shown in FIG. 7, when a load is placed on the loading platform unit 6 and a load from the loading platform unit 6 acts on the base plate 20, the pillar member 368 and the detection plate 372 move downward with respect to the upper housing 374 against the biasing force of the coil spring 370. At this time, when a load of a predetermined upper limit load (for example, 25 kgf) or more acts on the pillar member 368, as shown in FIG. 8, the detection plate 372 blocks the light between the light emitting element 420 and the light receiving element 422, and the overloading detection sensor 380 switches from off to on. Note that the pillar member 368 and the detection plate 372 can move downward with respect to the base plate 20 until the lower surface of the support member 366 abuts against the upper surface of the cushion 408. By adopting such a configuration, the overloading detection mechanism 302 can detect overloading on the loading platform unit 6.

[0042] As described above, the overloading detection sensor 380 is a non-contact detection sensor. Therefore, it is possible to suppress vibrations and impacts from the loading platform unit 6 from being transmitted to the overloading detection sensor 380 and causing the overloading detection sensor 380 to malfunction.

[0043] In the overloading detection mechanism 302, the upper housing 374, the lower housing 378, and the cap 382 cover the periphery of the coil spring 370, the detection plate 372, and the overloading detection sensor 380. By adopting such a configuration, it is possible to suppress foreign matter from adhering to the coil spring 370, the detection plate 372, the overloading detection sensor 380, etc. and affecting the operation of the overloading detection mechanism 302.

[0044] As shown in FIG. 3, both the upper right frame 30 and the upper left frame 32 are members made of aluminum, extend in the front-rear direction above the base plate 20, and are fixed to the upper surface of the base plate 20 respectively. The upper controller case 312 is a member made of resin and is fixed to the upper surface of the base plate 20 between the upper right frame 30 and the upper left frame 32. As shown in FIG. 9, an automatic driving control circuit board 426 is housed inside the upper controller case 312. The automatic driving control circuit board 426 is equipped with a wireless interface (hereinafter also referred to as I / F) 428 (see FIG. 30) electrically connected to a receiver mounted on the vehicle body unit 4, an automatic driving microcontroller unit (hereinafter also referred to as MCU) 430 (see FIG. 30) electrically connected to the wireless I / F 428, etc. The automatic driving control circuit board 426 is electrically connected to the main control circuit board 44 described later.

[0045] As shown in FIG. 3, the battery box 34 is a member made of resin, is disposed below the base plate 20 near the rear part of the base plate 20, and is fixed to the rear support member 24. As shown in FIG. 9, a battery mounting portion 40 for detachably mounting the battery pack 38 is provided inside the battery box 34. The battery pack 38 includes a secondary battery cell such as a lithium-ion battery cell, for example. The transport vehicle 2 operates with electric power supplied from the battery pack 38 attached to the battery mounting portion 40. A battery cover 42 that can be opened and closed is provided at the rear part of the battery box 34. By opening the battery cover 42 and sliding the battery pack 38 in the front-rear direction with respect to the battery mounting portion 40, the battery pack 38 can be attached to and detached from the battery mounting portion 40.

[0046] As shown in FIG. 2, the lower controller case 36 is a resin member and is disposed below the base plate 20 near the center of the base plate 20. The lower controller case 36 is fixed to the lower right frame 26 and the lower left frame 28 in a state of being placed on the upper surfaces of the lower right frame 26 and the lower left frame 28. As shown in FIGS. 9 and 10, the lower controller case 36 holds one main control circuit board 44, two drive control circuit boards 46 and 48, and four electric brake circuit boards 50, 52, 54, and 56.

[0047] As shown in FIG. 9, the main control circuit board 44 is housed inside the circuit board case 44a. The circuit board case 44a is housed in the rear inside the lower controller case 36. The circuit board case 44a is arranged such that the main control circuit board 44 extends along the vertical and horizontal directions. Mounted on the main control circuit board 44 are a control power circuit 432, a main MCU 434, a switching circuit 436, cutoff circuits 438, 440, 442 (see FIG. 30), etc., which will be described later.

[0048] As shown in FIG. 10, the drive control circuit boards 46 and 48 are respectively housed inside the circuit board cases 46a and 48a. As shown in FIG. 9, the circuit board cases 46a and 48a are housed in the front lower part inside the lower controller case 36. The circuit board cases 46a and 48a are arranged such that the drive control circuit boards 46 and 48 extend along the front-rear and left-right directions. The drive control circuit boards 46 and 48 are respectively electrically connected to the main control circuit board 44. Mounted on the drive control circuit board 46 are motor MCUs 444, 448, 452, motor drivers 454, 458, 462, an electromagnetic brake driver 464 (see FIG. 30), etc., which will be described later. Mounted on the drive control circuit board 48 are motor MCUs 446, 450, motor drivers 456, 460, an electromagnetic brake driver 466 (see FIG. 30), etc., which will be described later.

[0049] As shown in FIG. 10, the electric brake circuit boards 50, 52, 54, 56 are respectively attached to the heat dissipation cases 50a, 52a, 54a, 56a. The heat dissipation cases 50a, 52a, 54a, 56a respectively include circuit board accommodation portions 50b, 52b, 54b, 56b for accommodating the electric brake circuit boards 50, 52, 54, 56, heat dissipation fins 50c, 52c, 54c, 56c, and cooling fans 50d, 52d, 54d, 56d. The heat dissipation cases 50a, 52a are accommodated in the upper front part inside the lower controller case 36. The heat dissipation cases 50a, 52a are arranged such that the electric brake circuit boards 50, 52 are along the front-rear direction and the left-right direction, and the cooling fans 50d, 52d face upward. The heat dissipation cases 54a, 56a are fixed to a heat dissipation plate 58 fixed to the lower controller case 36 at the lower front part outside the lower controller case 36. The heat dissipation cases 54a, 56a are arranged such that the electric brake circuit boards 54, 56 are along the front-rear direction and the left-right direction, and the cooling fans 54d, 56d face downward. The electric brake circuit boards 50, 54 and the cooling fans 50d, 54d are electrically connected to the drive control circuit board 46. The electric brake circuit boards 52, 56 and the cooling fans 52d, 56d are electrically connected to the drive control circuit board 48. The electric brake circuit boards 50, 52, 54, 56 are respectively mounted with brake circuits 468, 470, 472, 474 (see FIG. 30) and the like described later.

[0050] (Cargo unit 6) As shown in Fig. 1, the loading platform unit 6 includes a main frame 60, a right guard 62, a left guard 64, and a front guard 66. The main frame 60, the right guard 62, the left guard 64, and the front guard 66 are all composed of steel round pipes. The main frame 60 is arranged above the base plate 20 of the chassis unit 4 along the front-rear direction and the left-right direction. The main frame 60 is fixed to the upper right frame 30 and the upper left frame 32 of the chassis unit 4 in a state of being placed on the upper surfaces of the upper right frame 30 and the upper left frame 32. On the upper surface of the main frame 60, the goods carried by the transport vehicle 2 are placed. The right guard 62 is attached to the right end of the main frame 60 so as to protrude above the upper surface of the main frame 60. The right guard 62 is arranged along the front-rear direction and the up-down direction. The left guard 64 is attached to the left end of the main frame 60 so as to protrude above the upper surface of the main frame 60. The left guard 64 is arranged along the front-rear direction and the up-down direction. The front guard 66 is attached to the front end of the main frame 60 so as to protrude above the upper surface of the main frame 60. The front guard 66 is arranged along the left-right direction and the up-down direction.

[0051] (Handle unit 8) As shown in Fig. 11, the handle unit 8 includes a switch box 70, a right handle 72, a left handle 74, a handle arm 76, a support pipe 78, a clamp member 80, a fixing member 82, a handle shaft 84, a base member 86, a rotation angle sensor 88, a movable cam member 90, a fixed cam member 92, and a coil spring 94. Hereinafter, the right handle 72, the left handle 74, the handle arm 76, and the support pipe 78 are also collectively referred to as the steering handle 73.

[0052] The switch box 70 is provided with a main power switch 96, a mode changeover switch 98, a trigger switch 100, a travel direction changeover switch 102, a speed changeover switch 104, a siren switch 106, and an LED 476. The main power switch 96 can switch the on / off of the main power supply of the carrier vehicle 2. The mode changeover switch 98 can switch the operation mode of the carrier vehicle 2 among a manual mode, an automatic mode, and a parking mode. The trigger switch 100 can switch the on / off of the forward and backward movement of the carrier vehicle 2 and adjust the traveling speed of the carrier vehicle 2 in the manual mode. The travel direction changeover switch 102 can switch the travel direction of the carrier vehicle 2 in the manual mode. The speed changeover switch 104 can switch the upper limit traveling speed of the carrier vehicle 2 in the manual mode. The siren switch 106 can sound a siren by means of a buzzer 478 (see FIG. 30) built in the switch box 70. The LED 476 can display the on / off of the main power supply of the carrier vehicle 2, the set travel direction, and the upper limit traveling speed. The main power switch 96, the mode changeover switch 98, the trigger switch 100, the travel direction changeover switch 102, the speed changeover switch 104, the siren switch 106, the LED 476, and the buzzer 478 are each electrically connected to the main control circuit board 44 (see FIG. 9).

[0053] The right handle 72 includes a support portion 72a extending in the vertical direction and a handle portion 72b bent rightward from the upper end of the support portion 72a. The lower end of the support portion 72a is fixed to the handle arm 76. A right grip 72c is provided at the right end of the handle portion 72b. The switch box 70 is fixed to the handle portion 72b to the left of the right grip 72c. The left handle 74 includes a support portion 74a extending in the vertical direction and a handle portion 74b bent leftward from the upper end of the support portion 74a. The lower end of the support portion 74a is fixed to the handle arm 76. A left grip 74c is provided at the left end of the handle portion 74b. The upper end of the support pipe 78 is fixed to the handle arm 76. The support pipe 78 extends in the vertical direction. The clamp member 80 includes clamp pieces 80a and 80b that sandwich the support pipe 78 from both the left and right sides. At the rear ends of the clamp pieces 80a and 80b, fastening portions 80c to be fastened by a fastener (not shown) are formed. When the fastener of the fastening portion 80c is tightened, the clamp pieces 80a and 80b are strongly pressed against the outer surface of the support pipe 78, and the support pipe 78 is fixed to the clamp member 80. When the fastener of the fastening portion 80c is loosened, the clamp pieces 80a and 80b are not pressed against the outer surface of the support pipe 78, and the support pipe 78 can move vertically with respect to the clamp member 80 and can rotate around the vertical direction. After adjusting the support pipe 78 to a desired position and angle with respect to the clamp member 80 in a state where the fastener of the fastening portion 80c is loosened, the position and angle of the support pipe 78 with respect to the clamp member 80 can be fixed by tightening the fastener of the fastening portion 80c.

[0054] As shown in FIG. 12, the front portion of the clamp member 80 is fixed to the fixed member 82. The upper end of the handle shaft 84 is fixed to the fixed member 82. The lower end of the handle shaft 84 is rotatably supported by the base member 86. The base member 86 is fixed to the upper surface of the base plate 20 of the vehicle body unit 4. A rotation angle sensor 88 is fixed to the lower portion of the base member 86. The rotation angle sensor 88 is connected to the lower end of the handle shaft 84. The rotation angle sensor 88 detects the rotation angle of the handle shaft 84 with respect to the base member 86. The rotation angle sensor 88 may be, for example, a potentiometer that detects a change in the electrical resistance value according to a change in the rotation angle. Alternatively, the rotation angle sensor 88 may be a magnetic rotary sensor including a Hall element whose position is fixed with respect to the base member 86 and a permanent magnet whose position is fixed with respect to the handle shaft 84. The rotation angle sensor 88 is electrically connected to the main control circuit board 44 (see FIG. 9).

[0055] As shown in FIG. 13, the handle shaft 84 is provided with a guide projection 84a. The guide projection 84a projects radially outward from the outer peripheral surface of the handle shaft 84 and extends along the axial direction of the handle shaft 84.

[0056] As shown in FIG. 14, the movable cam member 90 has a substantially cylindrical shape. Cam projections 90a and 90b extending downward are formed at the lower portion of the movable cam member 90. The cam projections 90a and 90b are respectively provided with first cam surfaces 90c and 90d and second cam surfaces 90e and 90f. When the movable cam member 90 is viewed from above, the first cam surfaces 90c and 90d are inclined so as to go upward from downward as it goes clockwise. When the movable cam member 90 is viewed from above, the second cam surfaces 90e and 90f are inclined so as to go upward from downward as it goes counterclockwise. A guide groove 90g is formed on the inner peripheral surface of the movable cam member 90. The guide groove 90g has a width corresponding to the guide projection 84a (see FIG. 13) and extends in a direction along the central axis of the movable cam member 90. When the movable cam member 90 is attached to the handle shaft 84, the guide projection 84a engages with the guide groove 90g so as to be slidable in the vertical direction. For this reason, the movable cam member 90 is held by the handle shaft 84 so as to be movable in the vertical direction. A spring receiving portion 90h for supporting the coil spring 94 is formed at the upper portion of the movable cam member 90. As shown in FIG. 12, the coil spring 94 biases the movable cam member 90 downward with respect to the fixed member 82.

[0057] As shown in FIG. 15, the fixed cam member 92 includes a cylindrical portion 92a having a substantially cylindrical shape and a flange portion 92b extending radially outward from the lower end of the cylindrical portion 92a. The fixed cam member 92 is fixed to the base member 86 by fastening the flange portion 92b to the upper surface of the base member 86 (see FIG. 12) with a fastener (not shown). Cam recesses 92c and 92d corresponding to the cam protrusions 90a and 90b of the movable cam member 90 are formed in the upper portion of the cylindrical portion 92a. First cam surfaces 92e and 92f and second cam surfaces 92g and 92h are provided in the cam recesses 92c and 92d, respectively. The first cam surfaces 92e and 92f correspond to the first cam surfaces 90c and 90d of the movable cam member 90, respectively. The second cam surfaces 92g and 92h correspond to the second cam surfaces 90e and 90f of the movable cam member 90, respectively. Further, stopper portions 92i and 92j are provided on the inner peripheral surface of the cylindrical portion 92a. As shown in FIG. 16, the stopper portions 92i and 92j regulate the rotation range of the handle shaft 84 by contacting the guide protrusion 84a of the handle shaft 84 when the handle shaft 84 rotates with respect to the fixed cam member 92.

[0058] In the handle unit 8 shown in FIG. 11, when the user rotates the steering handle 73 clockwise (or counterclockwise) when viewed from above, the handle shaft 84 rotates clockwise (or counterclockwise). At this time, as shown in FIG. 17, the movable cam member 90 rotates integrally with the handle shaft 84, so that the first cam surfaces 90c and 90d (or the second cam surfaces 90e and 90f) of the movable cam member 90 slide with respect to the first cam surfaces 92e and 92f (or the second cam surfaces 92g and 92h) of the fixed cam member 92, and the movable cam member 90 moves upward against the biasing force of the coil spring 94 while rotating relative to the fixed cam member 92. At this time, the torque due to the reaction force received by the movable cam member 90 from the fixed cam member 92 acts on the user who rotates the steering handle 73.

[0059] (Steering unit 10) As shown in FIG. 18, the steering unit 10 is attached to the front lower part of the base plate 20 (see FIG. 2) of the chassis unit 4 by means of the front support member 22. The steering unit 10 is connected to the front wheel unit 12 and steers the front wheel unit 12.

[0060] As shown in FIG. 19, the steering unit 10 includes a motor housing 160, a motor support member 162, a gear housing 164, a steering angle sensor 166, a steering shaft 168, a steering plate 170, a right tie rod 172, and a left tie rod 174. The motor housing 160 is fixed to the motor support member 162. The motor support member 162 is fixed to the gear housing 164. The gear housing 164 is fixed to the front support member 22 (see FIG. 18) of the chassis unit 4.

[0061] As shown in FIG. 20, a steering motor 176 is housed inside the motor housing 160. The steering motor 176 is, for example, an inner rotor type brushless DC motor. The steering motor 176 is electrically connected to the drive control circuit board 46 (see FIG. 10). The steering motor 176 includes a motor shaft 176a extending in the front-rear direction and a hall sensor 480 (see FIG. 34) for detecting the rotation of the motor shaft 176a. The motor shaft 176a is rotatably held by the motor housing 160 near the rear end and rotatably held by the motor support member 162 at the front. The front part of the motor shaft 176a penetrates the motor support member 162 and enters the inside of the gear housing 164. A gear portion 176b is formed near the front end of the motor shaft 176a.

[0062] Inside the gear housing 164, a spindle 178, a cam wheel 180, a movable gear 182, a coil spring 184, a cylindrical worm 186, a worm wheel 188, and an intermediate shaft 190 are accommodated. The spindle 178 is arranged along the front-rear direction. The spindle 178 is rotatably held by the gear housing 164 near the front end and at the rear part. Also, the spindle 178 is rotatably held by the motor support member 162 near the rear end.

[0063] The cam wheel 180 is fixed near the rear end of the spindle 178. As shown in FIG. 21, a cam groove 180a is formed on the front surface of the cam wheel 180. The movable gear 182 is attached to the spindle 178 in front of the cam wheel 180. The movable gear 182 is movable in the front-rear direction with respect to the spindle 178 and is held by the spindle 178 so as to be rotatable around the front-rear direction. A gear portion 182a that meshes with the gear portion 176b (see FIG. 20) of the motor shaft 176a is formed on the outer peripheral surface of the movable gear 182. A recess 182b into which the cam wheel 180 enters is formed at the rear part of the movable gear 182. A cam protrusion 182c corresponding to the cam groove 180a of the cam wheel 180 is formed in the recess 182b. The coil spring 184 is attached to the spindle 178 in front of the movable gear 182. The coil spring 184 is held by a spring receiving portion 178a provided on the spindle 178. The coil spring 184 biases the movable gear 182 toward the rear with respect to the spindle 178.

[0064] When the motor shaft 176a (see FIG. 20) rotates, the movable gear 182 also rotates. When the cam projection 182c of the movable gear 182 engages with the cam groove 180a of the cam wheel 180, the cam wheel 180 rotates as the movable gear 182 rotates, and thereby the spindle 178 also rotates. When the torque acting between the movable gear 182 and the cam wheel 180 is small, the engagement between the cam projection 182c and the cam groove 180a is maintained by the biasing force of the coil spring 184, and the transmission of rotation from the motor shaft 176a to the spindle 178 is maintained. On the other hand, when the torque acting between the movable gear 182 and the cam wheel 180 is large, the movable gear 182 moves forward against the biasing force of the coil spring 184, the engagement between the cam projection 182c and the cam groove 180a is released, and the transmission of rotation from the motor shaft 176a to the spindle 178 is interrupted. That is, the torque limiter 181 is constituted by the cam wheel 180, the movable gear 182, and the coil spring 184.

[0065] As shown in FIG. 20, the cylindrical worm 186 is fixed to the front portion of the spindle 178. The worm wheel 188 is arranged to mesh with the cylindrical worm 186. As shown in FIG. 22, the worm wheel 188 is fixed to the upper portion of the relay shaft 190. The relay shaft 190 is arranged along the vertical direction. The relay shaft 190 is rotatably held by the gear housing 164 near the upper end and at the central portion. A gear portion 190a is formed near the lower end of the relay shaft 190.

[0066] At the upper part of the gear housing 164, a steering angle sensor 166 is fixed. The steering angle sensor 166 is connected to the upper end of the relay shaft 190. The steering angle sensor 166 detects the rotation angle of the relay shaft 190 with respect to the gear housing 164. The steering angle sensor 166 may be, for example, a potentiometer that detects a change in electrical resistance value according to a change in the rotation angle. Alternatively, the steering angle sensor 166 may be a magnetic rotary sensor including a Hall element whose position is fixed with respect to the gear housing 164 and a permanent magnet whose position is fixed with respect to the relay shaft 190. The steering angle sensor 166 is electrically connected to the main control circuit board 44 (see FIG. 9).

[0067] The steering shaft 168 is rotatably held by the gear housing 164 near the upper end and at the upper part. The steering shaft 168 is arranged along the vertical direction. At the upper part of the steering shaft 168, a gear part 168a that meshes with the gear part 190a of the relay shaft 190 is formed. The lower end of the steering shaft 168 is fixed near the front end of the steering plate 170. As shown in FIG. 19, the steering plate 170 has an elongated flat plate shape having a longitudinal direction in the front-rear direction and a short direction in the left-right direction. Near the rear end of the steering plate 170, the rear end of the right tie rod 172 and the rear end of the left tie rod 174 are respectively connected. The rear end of the right tie rod 172 is rotatably connected to the steering plate 170 around two axes orthogonal to the longitudinal direction of the right tie rod 172. The rear end of the left tie rod 174 is rotatably connected to the steering plate 170 around two axes orthogonal to the longitudinal direction of the left tie rod 174.

[0068] As shown in FIG. 20, when the spindle 178 rotates due to the rotation of the motor shaft 176a, the rotation of the spindle 178 is transmitted to the relay shaft 190 via the cylindrical worm 186 and the worm wheel 188. As shown in FIG. 22, when the relay shaft 190 rotates, the steering shaft 168 rotates accordingly, and the rear end of the steering plate 170 rotates in the left - right direction. Due to the rotation of this steering plate 170, the right tie rod 172 and the left tie rod 174 shown in FIG. 19 move, and the front wheel unit 12 is steered. In the following description, the steering shaft 168, the steering plate 170, the right tie rod 172, the left tie rod 174, the spindle 178, the torque limiter 181, the cylindrical worm 186, the worm wheel 188, and the relay shaft 190 are collectively referred to as the transmission mechanism 169.

[0069] The main control circuit board 44 (see FIG. 9) calculates the steering angle to be realized in the steering unit 10 based on the detection signal from the rotation angle sensor 88 of the handle unit 8 (see FIG. 11) in the manual mode. Then, the main control circuit board 44 calculates the rotation angle to be realized by the steering motor 176 based on the steering angle to be realized in the steering unit 10, and instructs the drive control circuit board 46 to drive the steering motor 176. As a result, in the steering unit 10, a steering angle corresponding to the user's operation of the handle unit 8 is realized.

[0070] (Front wheel unit 12) As shown in FIG. 18, the front wheel unit 12 is attached to the front side support member 22 below the front part of the base plate 20 (see FIG. 2) of the vehicle body unit 4. The front wheel unit 12 includes a right front wheel unit 12a and a left front wheel unit 12b. The right front wheel unit 12a includes a right front wheel 192, a right side gear housing 194, a right side motor housing 196, a right side kingpin 198, a right side sleeve 200, an upper right side arm 202, a lower right side arm 204, a right side buffer member 206, and a right side steering plate 208. The left front wheel unit 12b includes a left front wheel 212, a left side gear housing 214, a left side motor housing 216, a left side kingpin 218, a left side sleeve 220, an upper left side arm 222, a lower left side arm 224, a left side buffer member 226, and a left side steering plate 228. In the following description, the right side gear housing 194, the right side kingpin 198, the right side sleeve 200, and the right side steering plate 208 are collectively referred to as the right side holding member 195, and the left side gear housing 214, the left side kingpin 218, the left side sleeve 220, and the left side steering plate 228 are collectively referred to as the left side holding member 215. Further, the right side holding member 195, the upper right side arm 202, the lower right side arm 204, the right side buffer member 206, the left side holding member 215, the upper left side arm 222, the lower left side arm 224, the left side buffer member 226, and the steering unit 10 are collectively referred to as the suspension mechanism 11.

[0071] As shown in FIG. 23, the right gear housing 194 is disposed on the left side of the right front wheel 192. The right motor housing 196 is fixed to the left part of the right gear housing 194. As shown in FIG. 24, a right front wheel motor 232 is accommodated inside the right motor housing 196. The right front wheel motor 232 is, for example, an inner rotor type brushless DC motor. The right front wheel motor 232 is electrically connected to a drive control circuit board 46 (see FIG. 10). The right front wheel motor 232 includes a right front wheel motor shaft 232a extending in the left-right direction and a hall sensor 482 (see FIG. 32) for detecting the rotation of the right front wheel motor shaft 232a. The right front wheel motor shaft 232a is rotatably held by the right motor housing 196 near the left end and rotatably held by the right gear housing 194 near the right end. The right front wheel 192 includes a right front wheel axle 192a extending leftward. The right front wheel axle 192a is rotatably held by the right gear housing 194 near the left end. A planetary gear mechanism 234 is accommodated inside the right gear housing 194. The planetary gear mechanism 234 decelerates the rotation of the right front wheel motor shaft 232a and transmits it to the right front wheel axle 192a. When the right front wheel motor 232 is driven, the rotation of the right front wheel motor shaft 232a is transmitted to the right front wheel axle 192a via the planetary gear mechanism 234, and the right front wheel 192 rotates.

[0072] The right kingpin 198 is fixed to the upper part of the right gear housing 194. The right kingpin 198 extends along the vertical direction. The upper part of the right kingpin 198 enters into the inside of the right sleeve 200. The right kingpin 198 is rotatably held by the right sleeve 200 near the upper end and the lower end of the right sleeve 200. As shown in FIG. 23, the right end of the upper right arm 202 is rotatably connected to the upper part of the right sleeve 200 around a rotation axis along the front-rear direction. The right end of the lower right arm 204 is rotatably connected to the lower part of the right sleeve 200 around a rotation axis along the front-rear direction. As shown in FIG. 18, the left end of the upper right arm 202 is rotatably connected to the upper right connecting portion 22a of the front support member 22 around a rotation axis along the front-rear direction. The left end of the lower right arm 204 is rotatably connected to the lower right connecting portion 22b of the front support member 22 around a rotation axis along the front-rear direction. Therefore, the right sleeve 200 is movably supported by the front support member 22 within the movable ranges of the upper right arm 202 and the lower right arm 204.

[0073] The right buffer member 206 includes a damper 206a and a coil spring 206b. The upper end of the right buffer member 206 is rotatably connected to the front surface of the front support member 22 around a rotation axis along the front-rear direction. The lower end of the right buffer member 206 is rotatably connected to the front surface of the lower right arm 204 around a rotation axis along the front-rear direction. Therefore, when the right front wheel 192 moves vertically with respect to the front support member 22, the impact and vibration from the right front wheel 192 being transmitted to the chassis unit 4 are suppressed by the damping force of the damper 206a and the elastic restoring force of the coil spring 206b.

[0074] As shown in FIG. 23, the right steering plate 208 is fixed near the lower end of the right kingpin 198. At the left front end of the right steering plate 208, the front end of the right tie rod 172 is rotatably connected about a biaxial direction orthogonal to the longitudinal direction of the right tie rod 172. When the right front wheel unit 12a is viewed from above, the right tie rod 172 intersects the upper right arm 202 and the lower right arm 204. When the front wheel unit 12 is steered to the right (or left) direction, the rear end of the steering plate 170 (see FIG. 19) moves to the right (or left) direction, whereby the right steering plate 208, the right kingpin 198, the right gear housing 194, the right motor housing 196, and the right front wheel 192 rotate clockwise (or counterclockwise) with respect to the right sleeve 200 when the right sleeve 200 is viewed from above with the axial direction of the right kingpin 198 as the steering axis.

[0075] As shown in FIG. 18, the left front wheel unit 12b has a structure symmetric to the right front wheel unit 12a with respect to left and right. Hereinafter, the left front wheel unit 12b will be described with reference to FIGS. 23 and 24 showing the right front wheel unit 12a.

[0076] As shown in FIG. 23, the left gear housing 214 is disposed on the right side of the left front wheel 212. The left motor housing 216 is fixed to the right portion of the left gear housing 214. As shown in FIG. 24, a left front wheel motor 242 is housed inside the left motor housing 216. The left front wheel motor 242 is, for example, an inner rotor type brushless DC motor. The left front wheel motor 242 is electrically connected to a drive control circuit board 48 (see FIG. 10). The left front wheel motor 242 includes a left front wheel motor shaft 242a extending in the left-right direction and a hall sensor 484 (see FIG. 32) for detecting the rotation of the left front wheel motor shaft 242a. The left front wheel motor shaft 242a is rotatably held by the left motor housing 216 near the right end and is rotatably held by the left gear housing 214 near the left end. The left front wheel 212 includes a left axle 212a extending rightward. The left axle 212a is rotatably held by the left gear housing 214 near the right end. A planetary gear mechanism 244 is housed inside the left gear housing 214. The planetary gear mechanism 244 decelerates the rotation of the left front wheel motor shaft 242a and transmits it to the left axle 212a. When the left front wheel motor 242 is driven, the rotation of the left front wheel motor shaft 242a is transmitted to the left axle 212a via the planetary gear mechanism 244, and the left front wheel 212 rotates.

[0077] The left kingpin 218 is fixed to the upper part of the left gear housing 214. The left kingpin 218 extends along the vertical direction. The upper part of the left kingpin 218 enters into the inside of the left sleeve 220. The left kingpin 218 is rotatably held by the left sleeve 220 near the upper end and the lower end of the left sleeve 220. As shown in FIG. 23, the left end of the upper left arm 222 is rotatably connected to the upper part of the left sleeve 220 around a rotation axis along the front-rear direction. The left end of the lower left arm 224 is rotatably connected to the lower part of the left sleeve 220 around a rotation axis along the front-rear direction. As shown in FIG. 18, the right end of the upper left arm 222 is rotatably connected to the upper left connecting portion 22c of the front support member 22 around a rotation axis along the front-rear direction. The right end of the lower left arm 224 is rotatably connected to the lower left connecting portion 22d of the front support member 22 around a rotation axis along the front-rear direction. Therefore, the left sleeve 220 is movably supported by the front support member 22 within the movable ranges of the upper left arm 222 and the lower left arm 224.

[0078] The left buffer member 226 includes a damper 226a and a coil spring 226b. The upper end of the left buffer member 226 is rotatably connected to the front surface of the front support member 22 around a rotation axis along the front-rear direction. The lower end of the left buffer member 226 is rotatably connected to the front surface of the lower left arm 224 around a rotation axis along the front-rear direction. Therefore, when the left front wheel 212 moves vertically with respect to the front support member 22, the impact and vibration from the left front wheel 212 are suppressed from being transmitted to the vehicle body unit 4 by the damping force of the damper 226a and the elastic restoring force of the coil spring 226b.

[0079] As shown in FIG. 23, the left steering plate 228 is fixed near the lower end of the left kingpin 218. The front end of the left tie rod 174 is rotatably connected to the right front end of the left steering plate 228 about two axes orthogonal to the longitudinal direction of the left tie rod 174. When the left front wheel unit 12b is viewed from above, the left tie rod 174 intersects the upper left arm 222 and the lower left arm 224. When the front wheel unit 12 is steered to the right (or left) direction, the rear end of the steering plate 170 (see FIG. 19) moves to the right (or left) direction, whereby the left steering plate 228, the left kingpin 218, the left gear housing 214, the left motor housing 216, and the left front wheel 212 rotate clockwise (or counterclockwise) with respect to the left sleeve 220 when the left sleeve 220 is viewed from above, with the axial direction of the left kingpin 218 as the steering axis.

[0080] (Rear wheel unit 14) As shown in FIG. 25, the rear wheel unit 14 is attached to the rear support member 24 below the rear part of the base plate 20 (see FIG. 2) of the vehicle body unit 4. The rear wheel unit 14 includes a right rear wheel unit 14a and a left rear wheel unit 14b. The right rear wheel unit 14a includes a right rear wheel 252, a right gear housing 254, a right motor housing 256, a right brake housing 258, a right clutch lever 260, and a right buffer member 264. The left rear wheel unit 14b includes a left rear wheel 272, a left gear housing 274, a left motor housing 276, a left brake housing 278, a left clutch lever 280, and a left buffer member 284.

[0081] As shown in FIG. 26, the right gear housing 254 is disposed on the left side of the right rear wheel 252 and rotatably holds the right rear wheel axle (not shown) of the right rear wheel 252. The right gear housing 254 extends forward and upward from the right rear wheel axle. The right motor housing 256 is fixed to the left part above the front of the right gear housing 254. The right brake housing 258 is fixed to the left part of the right motor housing 256. Inside the right motor housing 256, a right rear wheel motor 486 (see FIG. 30) is accommodated. The right rear wheel motor 486 is, for example, an inner rotor type brushless DC motor. The right rear wheel motor 486 is electrically connected to a drive control circuit board 46 (see FIG. 10). The right rear wheel motor 486 includes a right rear wheel motor shaft (not shown) extending in the left-right direction and a hall sensor 488 (see FIG. 32) for detecting the rotation of the right rear wheel motor shaft. The right rear wheel electromagnetic brake 490 (see FIG. 30) is accommodated in the right brake housing 258. The right rear wheel electromagnetic brake 490 is connected to the right rear wheel motor shaft. The right rear wheel electromagnetic brake 490 switches between a state allowing the rotation of the right rear wheel motor shaft and a state prohibiting the rotation. The right rear wheel electromagnetic brake 490 is electrically connected to the drive control circuit board 46 (see FIG. 10). In the parking mode, the right rear wheel electromagnetic brake 490 is maintained in a state of prohibiting the rotation of the right rear wheel motor shaft.

[0082] Inside the right gear housing 254, a spur gear mechanism (not shown) and a clutch mechanism (not shown) are accommodated. The spur gear mechanism decelerates the rotation of the right rear wheel motor shaft and transmits it to the right rear axle. When the right rear wheel motor 486 is driven, the rotation of the right rear wheel motor shaft is transmitted to the right rear axle via the spur gear mechanism, and the right rear wheel 252 rotates. The clutch mechanism switches between a state that allows the transmission of rotation from the right rear wheel motor shaft to the right rear axle and a state that blocks it in response to an operation on the right clutch lever 260. Therefore, when the right rear wheel electromagnetic brake 490 prohibits the rotation of the right rear wheel motor shaft, by switching the clutch mechanism to a state that blocks the transmission of rotation from the right rear wheel motor shaft to the right rear axle, it is possible to prevent the right rear wheel 252 from locking up.

[0083] Near the front upper end of the right gear housing 254, a connecting portion 254a is provided. The connecting portion 254a is connected to the rear support member 24 so as to be rotatable about a rotation axis along the left - right direction. The right buffer member 264 includes a damper 264a and a coil spring 264b. The upper end of the right buffer member 264 is connected to the rear support member 24 so as to be rotatable about a rotation axis along the left - right direction, behind and above the connecting portion 254a. The lower end of the right buffer member 264 is connected to the rear upper surface of the right gear housing 254 so as to be rotatable about a rotation axis along the left - right direction. Therefore, when the right rear wheel 252 moves vertically with respect to the rear support member 24, the impact and vibration from the right rear wheel 252 being transmitted to the vehicle body unit 4 are suppressed by the damping force of the damper 264a and the elastic restoring force of the coil spring 264b.

[0084] As shown in FIG. 25, the left rear wheel unit 14b has a structure symmetric to the right rear wheel unit 14a. Hereinafter, the left rear wheel unit 14b will be described with reference to FIG. 26 which shows the right rear wheel unit 14a.

[0085] As shown in FIG. 26, the left gear housing 274 is disposed on the right side of the left rear wheel 272 and rotatably holds the left rear wheel axle (not shown) of the left rear wheel 272. The left gear housing 274 extends forward and upward from the left rear wheel axle. The left motor housing 276 is fixed to the upper right part in front of the left gear housing 274. The left brake housing 278 is fixed to the right part of the left motor housing 276. Inside the left motor housing 276, a left rear wheel motor 492 (see FIG. 30) is accommodated. The left rear wheel motor 492 is, for example, an inner rotor type brushless DC motor. The left rear wheel motor 492 is electrically connected to a drive control circuit board 48 (see FIG. 10). The left rear wheel motor 492 includes a left rear wheel motor shaft (not shown) extending in the left-right direction and a hall sensor 494 (see FIG. 32) for detecting the rotation of the left rear wheel motor shaft. In the left brake housing 278, a left rear wheel electromagnetic brake 496 (see FIG. 30) is accommodated. The left rear wheel electromagnetic brake 496 is connected to the left rear wheel motor shaft. The left rear wheel electromagnetic brake 496 switches between a state allowing the rotation of the left rear wheel motor shaft and a state prohibiting the rotation. The left rear wheel electromagnetic brake 496 is electrically connected to the drive control circuit board 48 (see FIG. 10). The drive control circuit board 48 controls the operation of the left rear wheel electromagnetic brake 496. In the parking mode, the left rear wheel electromagnetic brake 496 is maintained in a state of prohibiting the rotation of the left rear wheel motor shaft.

[0086] Inside the left gear housing 274, a spur gear mechanism (not shown) and a clutch mechanism (not shown) are accommodated. The spur gear mechanism decelerates the rotation of the left rear wheel motor shaft and transmits it to the left rear axle. When the left rear wheel motor 492 is driven, the rotation of the left rear wheel motor shaft is transmitted to the left rear axle via the spur gear mechanism, and the left rear wheel 272 rotates. The clutch mechanism switches between a state that allows the transmission of rotation from the left rear wheel motor shaft to the left rear axle and a state that blocks it in response to an operation on the left clutch lever 280. Therefore, when the left rear wheel electromagnetic brake 496 prohibits the rotation of the left rear wheel motor shaft, by switching the clutch mechanism to a state that blocks the transmission of rotation from the left rear wheel motor shaft to the left rear axle, it is possible to prevent the left rear wheel 272 from locking up.

[0087] Near the front upper end of the left gear housing 274, a connecting portion 274a is provided. The connecting portion 274a is connected to the rear support member 24 so as to be rotatable around a rotation axis along the left - right direction. The left shock absorber member 284 includes a damper 284a and a coil spring 284b. The upper end of the left shock absorber member 284 is connected to the rear support member 24 above and behind the connecting portion 274a so as to be rotatable around a rotation axis along the left - right direction. The lower end of the left shock absorber member 284 is connected to the rear upper surface of the left gear housing 274 so as to be rotatable around a rotation axis along the left - right direction. Therefore, when the left rear wheel 272 moves vertically with respect to the rear support member 24, the impact and vibration from the left rear wheel 272 being transmitted to the vehicle body unit 4 are suppressed by the damping force of the damper 284a and the elastic restoring force of the coil spring 284b.

[0088] (Bumper unit 16) As shown in FIG. 1, the bumper unit 16 is attached to the front lower part of the base plate 20 of the chassis unit 4 and is attached to the front support member 22. As shown in FIG. 27, the bumper unit 16 includes a base member 500, a housing 502, a right headlight 504, a left headlight 506, a bumper frame 508, bumper support members 510 and 512, linear motion pipes 514 and 516, coil springs 518 and 520, linear motion bearings 522 and 524 (see FIG. 28), contact plates 526 and 528 (see FIG. 29), and collision detection switches 530 and 532 (see FIG. 29).

[0089] The base member 500 is fixed to the front support member 22 (see FIG. 2) of the chassis unit 4. As shown in FIG. 27, the housing 502 is fixed to the base member 500. The housing 502 includes a housing portion 502a having a substantially rectangular parallelepiped box shape with a longitudinal direction in the left - right direction, a right support portion 502b formed at the right end of the housing portion 502a, and a left support portion 502c formed at the left end of the housing portion 502a. The right headlight 504 is fixed to the right support portion 502b. The left headlight 506 is fixed to the left support portion 502c. The right headlight 504 and the left headlight 506 each illuminate the front of the transport vehicle 2. The right headlight 504 and the left headlight 506 are each electrically connected to the main control circuit board 44 (see FIG. 9).

[0090] The bumper frame 508 is composed of a steel round pipe. The bumper support members 510 and 512 are each disposed behind the bumper frame 508 and are fixed to the bumper frame 508. The bumper support member 510 is attached to the linear motion pipe 514 via bolts 534a, 534b and nuts 536a, 536b (see FIG. 28). The bumper support member 512 is attached to the linear motion pipe 516 via bolts 538a, 538b and nuts 540a, 540b.

[0091] As shown in FIG. 28, the linear motion pipe 514 is arranged such that its longitudinal direction is along the front-rear direction. Near the front end of the linear motion pipe 514, elongated holes 514a and 514b are formed which are arranged side by side in the front-rear direction and each has a longitudinal direction in the front-rear direction. Bolt 534a passes through the elongated hole 514a, and bolt 534b passes through the elongated hole 514b. Therefore, the bumper support member 510 is supported by the linear motion pipe 514 so as to be movable in the front-rear direction between a position where bolts 534a and 534b abut against the front edges of the elongated holes 514a and 514b and a position where bolts 534a and 534b abut against the rear edges of the elongated holes 514a and 514b. Similarly, the linear motion pipe 516 is arranged such that its longitudinal direction is along the front-rear direction. Near the front end of the linear motion pipe 516, elongated holes 516a and 516b are formed which are arranged side by side in the front-rear direction and each has a longitudinal direction in the front-rear direction. Bolt 538a passes through the elongated hole 516a, and bolt 538b passes through the elongated hole 516b. Therefore, the bumper support member 512 is supported by the linear motion pipe 516 so as to be movable in the front-rear direction between a position where bolts 538a and 538b abut against the front edges of the elongated holes 516a and 516b and a position where bolts 538a and 538b abut against the rear edges of the elongated holes 516a and 516b.

[0092] The rear ends of the linear motion pipes 514 and 516 penetrate the front wall of the base member 500 and the housing 502 and enter the interior of the housing 502. The linear motion pipes 514 and 516 are supported by linear bearings 522 and 524 so as to be movable in the front-rear direction near their rear ends. The linear bearings 522 and 524 are fixed to the front wall of the housing 502. Coil springs 518 and 520 are attached to the linear motion pipes 514 and 516. The front ends of the coil springs 518 and 520 abut against the rear surfaces of the bumper support members 510 and 512, and the rear ends of the coil springs 518 and 520 abut against the front surface of the base member 500. The coil springs 518 and 520 bias the bumper support members 510 and 512 forward with respect to the base member 500.

[0093] As shown in FIG. 29, contact plates 526 and 528 are fixed to the rear ends of the linear motion pipes 514 and 516. The contact plates 526 and 528 are provided with contact portions 526a and 528a that extend radially outward. Collision detection switches 530 and 532 are disposed in front of the contact portions 526a and 528a. In a state where no external force is acting on the bumper frame 508, the linear motion pipes 514 and 516 move forward with respect to the housing 502 due to the biasing force of the coil springs 518 and 520. In this case, the contact portions 526a and 528a are in contact with the collision detection switches 530 and 532, and the collision detection switches 530 and 532 are off. When a rearward external force acts on the bumper frame 508, the linear motion pipes 514 and 516 move rearward with respect to the housing 502 against the biasing force of the coil springs 518 and 520. In this case, the contact portions 526a and 528a separate from the collision detection switches 530 and 532, and the collision detection switches 530 and 532 turn on. The collision detection switches 530 and 532 are each electrically connected to the main control circuit board 44 (see FIG. 9).

[0094] (Circuit Configuration of the Carrier 2) As shown in FIG. 30, the control power supply circuit 432 is electrically connected to the main power switch 96. When the main power switch 96 is turned on, the control power supply circuit 432 allows the supply of power from the battery pack 38, and when the main power switch 96 is turned off, the control power supply circuit 432 prohibits the supply of power from the battery pack 38. When the main power of the carrier vehicle 2 is on, the control power supply circuit 432 supplies the power supplied from the battery pack 38 to the cutoff circuits 438, 440, 442 without stepping down the voltage (Vbat) of the battery pack 38. Also, when the main power of the carrier vehicle 2 is on, the control power supply circuit 432 steps down the power supplied from the battery pack 38 from the voltage (Vbat) of the battery pack 38 to a predetermined voltage (Vcc) and supplies it to each electronic component such as the main MCU 434, the switching circuit 436, the automatic driving MCU 430, and the motor MCUs 444, 446, 448, 450, 452. Hereinafter, the potential of the voltage (Vbat) of the battery pack 38 is also referred to as the battery potential, and the potential of the voltage (Vcc) stepped down by the control power supply circuit 432 is also referred to as the power supply potential.

[0095] The main MCU 434 controls the overall operation of the carrier vehicle 2. The main MCU 434 is electrically connected to the main power switch 96, the speed changeover switch 104, the siren switch 106, the LED 476, the buzzer 478, the steering angle sensor 166, the overload detection sensors 320a, 320b, 320c, 320d, the right headlight 504, and the left headlight 506. Also, the main MCU 434 is electrically connected to the mode changeover switch 98, the trigger switch 100, the traveling direction changeover switch 102, the emergency stop switch 308, the collision detection switches 530, 532, and the rotation angle sensor 88 via the switching circuit 436. Further, the main MCU 434 is electrically connected to the wireless I / F 428 via the automatic driving MCU 430. Based on the signal from the wireless I / F 428, the automatic driving MCU 430 generates a traveling trajectory that the carrier vehicle 2 should achieve during following driving or remote control driving in the automatic mode and outputs it as a command value to the main MCU 434.

[0096] The motor MCUs 444, 446, 448, 450, 452 are electrically connected to the main MCU 434. The motor MCU 444 controls the operation of the right front wheel motor 232 via the motor driver 454, and also controls the operations of the brake circuit 468 and the cooling fan 50d. The motor MCU 446 controls the operation of the left front wheel motor 242 via the motor driver 456, and also controls the operations of the brake circuit 470 and the cooling fan 52d. The motor MCU 448 controls the operation of the right rear wheel motor 486 via the motor driver 458, and also controls the operations of the brake circuit 472 and the cooling fan 54d. Also, the motor MCU 448 controls the operation of the right rear wheel electromagnetic brake 490 via the electromagnetic brake driver 464. The motor MCU 450 controls the operation of the left rear wheel motor 492 via the motor driver 460, and also controls the operations of the brake circuit 474 and the cooling fan 56d. Also, the motor MCU 450 controls the operation of the left rear wheel electromagnetic brake 496 via the electromagnetic brake driver 466. The motor MCU 452 controls the operation of the steering motor 176 via the motor driver 462.

[0097] The cutoff circuit 438 is provided on the power supply path from the control power supply circuit 432 to the motor drivers 454, 456, 458, 460. The cutoff circuit 438 switches between a state that permits the power supply from the control power supply circuit 432 to the motor drivers 454, 456, 458, 460 and a state that prohibits it. The cutoff circuit 440 is provided on the power supply path from the control power supply circuit 432 to the electromagnetic brake drivers 464, 466. The cutoff circuit 440 switches between a state that permits the power supply from the control power supply circuit 432 to the electromagnetic brake drivers 464, 466 and a state that prohibits it. The cutoff circuit 442 is provided on the power supply path from the control power supply circuit 432 to the motor driver 462. The cutoff circuit 442 switches between a state that permits the power supply from the control power supply circuit 432 to the motor driver 462 and a state that prohibits it. The cutoff circuits 438, 440, 442 are all electrically connected to the main MCU 434 and the switching circuit 436.

[0098] (Configuration of the switching circuit 436) As shown in FIG. 31, the switching circuit 436 includes cancellation circuits 542, 544, 546, a delay circuit 548, AND gates 550, 552, OR gates 554, 556, NOT gates 558, 560, 562, 564, 566, and resistors 568, 570, 572, 574, 576, 578.

[0099] The mode switch 98 includes a ground terminal 98a, a manual mode terminal 98b, and an automatic mode terminal 98c. The ground terminal 98a is connected to the ground potential. The manual mode terminal 98b is connected to the power supply potential via the resistor 568 and is also connected to the main MCU 434. The automatic mode terminal 98c is connected to the power supply potential via the resistor 570 and is also connected to the main MCU 434.

[0100] When the user selects the manual mode on the mode switch 98, the ground terminal 98a and the manual mode terminal 98b become conductive, and the ground terminal 98a and the automatic mode terminal 98c become non-conductive. In this case, the manual mode terminal 98b becomes the L potential, and the automatic mode terminal 98c becomes the H potential. When the input from the manual mode terminal 98b becomes the L potential, the main MCU 434 recognizes that the manual mode has been selected by the user. When the user selects the automatic mode on the mode switch 98, the ground terminal 98a and the manual mode terminal 98b become non-conductive, and the ground terminal 98a and the automatic mode terminal 98c become conductive. In this case, the manual mode terminal 98b becomes the H potential, and the automatic mode terminal 98c becomes the L potential. When the input from the automatic mode terminal 98c becomes the L potential, the main MCU 434 recognizes that the automatic mode has been selected by the user. When the user selects the parking mode on the mode switch 98, the ground terminal 98a and the manual mode terminal 98b become non-conductive, and the ground terminal 98a and the automatic mode terminal 98c also become non-conductive. In this case, the manual mode terminal 98b becomes the H potential, and the automatic mode terminal 98c also becomes the H potential. When both the input from the manual mode terminal 98b and the input from the automatic mode terminal 98c become the H potential, the main MCU 434 recognizes that the parking mode has been selected by the user.

[0101] The cancellation circuit 542 includes a transistor 542a and resistors 542b, 542c, and 542d. The transistor 542a is a PNP-type transistor. One end of the resistor 542b is connected to the emitter of the transistor 542a, and the other end is connected to the base of the transistor 542a. One end of the resistor 542c is connected to the base of the transistor 542a, and the other end is connected to the automatic mode terminal 98c of the mode switch 98. One end of the resistor 542d is connected to the rotation angle sensor 88, and the other end is connected to the collector of the transistor 542a. Also, the emitter of the transistor 542a is connected to the power supply potential, and the collector of the transistor 542a is connected to the main MCU 434.

[0102] The rotation angle sensor 88 outputs a potential corresponding to the rotation angle to the cancellation circuit 542. When the automatic mode terminal 98c is at the H potential, the transistor 542a is off, and the potential output from the rotation angle sensor 88 is input to the main MCU 434. When the automatic mode terminal 98c is at the L potential, the transistor 542a turns on, and an H potential is input to the main MCU 434 regardless of the potential output from the rotation angle sensor 88. That is, the cancellation circuit 542 cancels the input signal from the rotation angle sensor 88 when the automatic mode is selected in the mode switch 98.

[0103] The trigger switch 100 includes a ground terminal 100a, a trigger terminal 100b, and a variable resistor 100c. The ground terminal 100a is connected to the ground potential. The trigger terminal 100b is connected to the power supply potential via a resistor 572. When the user does not turn on the trigger switch 100, the ground terminal 100a and the trigger terminal 100b are non-conductive, and the trigger terminal 100b is at the H potential. When the user turns on the trigger switch 100, the ground terminal 100a and the trigger terminal 100b are conductive, and the trigger terminal 100b is at the L potential. One end of the variable resistor 100c of the trigger switch 100 is connected to the ground potential, and the other end is connected to the power supply potential, and outputs a potential corresponding to the pushing amount when the user turns on the trigger switch 100 to the cancel circuit 544.

[0104] The cancel circuit 544 includes a transistor 544a and resistors 544b, 544c, and 544d. The transistor 544a is a PNP-type transistor. One end of the resistor 544b is connected to the emitter of the transistor 544a, and the other end is connected to the base of the transistor 544a. One end of the resistor 544c is connected to the base of the transistor 544a, and the other end is connected to the automatic mode terminal 98c of the mode changeover switch 98. One end of the resistor 544d is connected to the variable resistor 100c of the trigger switch 100, and the other end is connected to the collector of the transistor 544a. Also, the emitter of the transistor 544a is connected to the power supply potential, and the collector of the transistor 544a is connected to the main MCU 434.

[0105] When the automatic mode terminal 98c is at the H potential, the transistor 544a is off, and the potential output from the variable resistor 100c is input to the main MCU 434. In this case, the main MCU 434 recognizes the user's operation on the trigger switch 100 based on the potential output from the variable resistor 100c. When the automatic mode terminal 98c is at the L potential, the transistor 544a is turned on, and an H potential is input to the main MCU 434 regardless of the potential output from the variable resistor 100c. That is, the cancellation circuit 544 cancels the input signal from the variable resistor 100c of the trigger switch 100 when the automatic mode is selected in the mode changeover switch 98.

[0106] The trigger terminal 100b of the trigger switch 100 is connected to the first input terminal of the OR gate 554 via the NOT gate 558. The automatic mode terminal 98c of the mode changeover switch 98 is connected to the second input terminal of the OR gate 554 via the NOT gate 560. The output terminal of the OR gate 554 is connected to the first input terminal of the AND gate 550. The output terminal of the AND gate 550 is connected to the cutoff circuit 438. As will be described later, the cutoff circuit 438 permits the power supply to the motor drivers 454, 456, 458, 460 when the output terminal of the AND gate 550 is at the H potential, and cuts off the power supply to the motor drivers 454, 456, 458, 460 when the output terminal of the AND gate 550 is at the L potential.

[0107] As will be described later, an H potential is normally input to the second input terminal of the AND gate 550. In this case, if the automatic mode terminal 98c is at the H potential, when the trigger terminal 100b is at the H potential, the output terminals of the OR gate 554 and the AND gate 550 become the L potential, and when the trigger terminal 100b is at the L potential, the output terminals of the OR gate 554 and the AND gate 550 become the H potential. Therefore, when the automatic mode is not selected by the mode changeover switch 98, if the trigger switch 100 is turned on, an H potential is input to the cutoff circuit 438, and if the trigger switch 100 is not turned on, an L potential is input to the cutoff circuit 438. On the other hand, if the automatic mode terminal 98c is at the L potential, regardless of the potential of the trigger terminal 100b, the output terminals of the OR gate 554 and the AND gate 550 become the H potential. Therefore, when the automatic mode is selected by the mode changeover switch 98, an H potential is input from the switching circuit 436 to the cutoff circuit 438 regardless of whether the trigger switch 100 is turned on or not.

[0108] The output terminal of the AND gate 550 is also connected to the input terminal of the delay circuit 548. The output terminal of the delay circuit 548 is connected to the cutoff circuit 440. As will be described later, the cutoff circuit 440 permits the power supply to the electromagnetic brake drivers 464 and 466 when the output terminal of the delay circuit 548 is at the H potential, and cuts off the power supply to the electromagnetic brake drivers 464 and 466 when the output terminal of the delay circuit 548 is at the L potential. The delay circuit 548 includes a diode 548a, a resistor 548b, a capacitor 548c, and a buffer gate 548d. The anode of the diode 548a is connected to the input terminal of the delay circuit 548. The cathode of the diode 548a is connected to the input terminal of the buffer gate 548d. One end of the resistor 548b is connected to the cathode of the diode 548a, and the other end is connected to the ground potential. One end of the capacitor 548c is connected to the cathode of the diode 548a, and the other end is connected to the ground potential. The output terminal of the buffer gate 548d is connected to the output terminal of the delay circuit 548. When the output terminal of the AND gate 550 switches from the L potential to the H potential, after a predetermined delay time determined by the time constant of the resistor 548b and the capacitor 548c has elapsed, the output terminal of the delay circuit 548 also switches from the L potential to the H potential. Also, when the output terminal of the AND gate 550 switches from the H potential to the L potential, after a predetermined delay time determined by the time constant of the resistor 548b and the capacitor 548c has elapsed, the output terminal of the delay circuit 548 also switches from the H potential to the L potential.

[0109] The emergency stop switch 308 includes a ground terminal 308a and an emergency stop terminal 308b. The ground terminal 308a is connected to the ground potential. The emergency stop terminal 308b is connected to the power supply potential via a resistor 574 and is also connected to the main MCU 434. When the emergency stop switch 308 is off, the ground terminal 308a and the emergency stop terminal 308b are conductive, and the emergency stop terminal 308b becomes the L potential. When the emergency stop switch 308 is on, the ground terminal 308a and the emergency stop terminal 308b are non-conductive, and the emergency stop terminal 308b becomes the H potential. When the input from the emergency stop terminal 308b is at the H potential, the main MCU 434 recognizes that the emergency stop switch 308 has been turned on by the user.

[0110] The collision detection switch 530 includes a ground terminal 530a and a collision detection terminal 530b. The collision detection switch 532 includes a ground terminal 532a and a collision detection terminal 532b. The ground terminal 530a is connected to the ground potential. The collision detection terminal 530b is connected to the ground terminal 532a. The collision detection terminal 532b is connected to the power supply potential via a resistor 576 and is also connected to the main MCU 434. When the collision detection switch 530 is off, the ground terminal 530a and the collision detection terminal 530b are conductive. When the collision detection switch 530 is on, the ground terminal 530a and the collision detection terminal 530b are non-conductive. When the collision detection switch 532 is off, the ground terminal 532a and the collision detection terminal 532b are conductive. When the collision detection switch 532 is on, the ground terminal 532a and the collision detection terminal 532b are non-conductive. Therefore, when both of the collision detection switches 530 and 532 are off, the collision detection terminal 532b becomes the L potential. When one or both of the collision detection switches 530 and 532 are on, the collision detection terminal 532b becomes the H potential. When the input from the collision detection terminal 532b is at the H potential, the main MCU 434 recognizes that a collision has been detected by the collision detection switches 530 and 532.

[0111] The forward / reverse switch 102 includes a ground terminal 102a and a forward / reverse terminal 102b. The ground terminal 102a is connected to the ground potential. The forward / reverse terminal 102b is connected to the cancel circuit 546. In the forward / reverse switch 102, when forward is selected by the user, the ground terminal 102a and the forward / reverse terminal 102b are non-conductive, and when reverse is selected by the user, the ground terminal 102a and the forward / reverse terminal 102b are conductive.

[0112] The cancel circuit 546 includes a transistor 546a and resistors 546b, 546c, 546d. The transistor 546a is a PNP-type transistor. One end of the resistor 546b is connected to the emitter of the transistor 546a, and the other end is connected to the base of the transistor 546a. One end of the resistor 546c is connected to the base of the transistor 546a, and the other end is connected to the automatic mode terminal 98c of the mode switch 98. One end of the resistor 546d is connected to the forward / reverse terminal 102b of the forward / reverse switch 102, and the other end is connected to the collector of the transistor 546a. Also, the emitter of the transistor 546a is connected to the power supply potential, and the collector of the transistor 546a is connected to the power supply potential via the resistor 578 and is also connected to the main MCU 434.

[0113] When the automatic mode terminal 98c is at the H potential, the transistor 546a is off, and the collector of the transistor 546a becomes H potential if forward is selected by the forward / reverse switching switch 102, and becomes L potential if reverse is selected by the forward / reverse switching switch 102. In this case, the main MCU 434 recognizes which of forward and reverse is selected based on the input potential. When the automatic mode terminal 98c is at the L potential, the transistor 546a is on, and the collector of the transistor 546a becomes H potential regardless of whether forward or reverse is selected by the forward / reverse switching switch 102. That is, the cancel circuit 546 cancels the input signal from the forward / reverse switching switch 102 when the automatic mode is selected in the mode switching switch 98.

[0114] The emergency stop terminal 308b of the emergency stop switch 308 is connected to the first input terminal of the AND gate 552 via the NOT gate 562. The collision detection terminal 532b of the collision detection switch 532 is connected to the first input terminal of the OR gate 556 via the NOT gate 562. The collector of the transistor 546a of the cancel circuit 546 is connected to the second input terminal of the OR gate 556 via the NOT gate 564. The output terminal of the OR gate 556 is connected to the second input terminal of the AND gate 552. The output terminal of the AND gate 552 is connected to the second input terminal of the AND gate 550 and is also connected to the cutoff circuit 442. As will be described later, the cutoff circuit 442 permits the power supply to the motor driver 462 when the output terminal of the AND gate 552 is at the H potential, and cuts off the power supply to the motor driver 462 when the output terminal of the AND gate 552 is at the L potential.

[0115] When the emergency stop terminal 308b is at the H potential, regardless of the potential of the output terminal of the OR gate 556, the output terminal of the AND gate 552 becomes the L potential. For this reason, when the emergency stop switch 308 is turned on, regardless of the states of the mode changeover switch 98, the collision detection switches 530 and 532, and the traveling direction changeover switch 102, an L potential is input to the second input terminal of the AND gate 550, and an L potential is input from the switching circuit 436 to the cutoff circuit 442.

[0116] When the emergency stop terminal 308b is at the L potential and an L potential is input to the second input terminal of the OR gate 556, if the collision detection terminal 532b is at the L potential, the output terminals of the OR gate 556 and the AND gate 552 become the H potential, and if the collision detection terminal 532b is at the H potential, the output terminals of the OR gate 556 and the AND gate 552 become the L potential. For this reason, if no collision is detected by the collision detection switches 530 and 532, the second input terminal of the AND gate 550 becomes the H potential, and an H potential is input from the switching circuit 436 to the cutoff circuit 442. When a collision is detected by the collision detection switches 530 and 532, an L potential is input to the second input terminal of the AND gate 550, and an L potential is input from the switching circuit 436 to the cutoff circuit 442. That is, the collision detection by the collision detection switches 530 and 532 is enabled.

[0117] When the emergency stop terminal 308b is at the L potential and an H potential is input to the second input terminal of the OR gate 556, regardless of the potential of the collision detection terminal 532b, the output terminals of the OR gate 556 and the AND gate 552 become the H potential. For this reason, regardless of the states of the collision detection switches 530 and 532, an H potential is input to the second input terminal of the AND gate 550, and an H potential is input from the switching circuit 436 to the cutoff circuit 442. That is, the collision detection by the collision detection switches 530 and 532 is disabled.

[0118] When the automatic mode terminal 98c is at the H potential, since the transistor 546a of the cancel circuit 546 is off, if the forward direction terminal 102b is at the H potential, an L potential is input to the second input terminal of the OR gate 556, and if the forward direction terminal 102b is at the L potential, an H potential is input to the second input terminal of the OR gate 556. That is, when the automatic mode is not selected by the mode changeover switch 98, if forward is selected by the forward direction changeover switch 102, collision detection by the collision detection switches 530 and 532 is enabled, and if reverse is selected by the forward direction changeover switch 102, collision detection by the collision detection switches 530 and 532 is disabled.

[0119] When the automatic mode terminal 98c is at the L potential, since the transistor 546a of the cancel circuit 546 is on, an L potential is input to the second input terminal of the OR gate 556 regardless of the potential of the forward direction terminal 102b. That is, when the automatic mode is selected by the mode changeover switch 98, collision detection by the collision detection switches 530 and 532 is enabled regardless of the state of the forward direction changeover switch 102.

[0120] (Configuration of the cutoff circuit 438) As shown in FIG. 32, the cutoff circuit 438 includes a switching element 438a, a driver IC 438b, and an AND gate 438c. The switching element 438a is, for example, a field effect transistor, and more specifically, an n-channel MOSFET having an insulated gate. The drain of the switching element 438a is connected to the battery potential (Vbat) output of the control power supply circuit 432, the source of the switching element 438a is connected to the motor drivers 454, 456, 458, 460, and the gate of the switching element 438a is connected to the driver IC 438b. The first input terminal of the AND gate 438c is connected to the switching circuit 436, the second input terminal of the AND gate 438c is connected to the main MCU 434, and the output terminal of the AND gate 438c is connected to the driver IC 438b. The driver IC 438b turns on the switching element 438a when the output terminal of the AND gate 438c is at the H potential, that is, when both the first input terminal and the second input terminal of the AND gate 438c are at the H potential. The driver IC 438b turns off the switching element 438a when the output terminal of the AND gate 438c is at the L potential, that is, when one or both of the first input terminal and the second input terminal of the AND gate 438c are at the L potential.

[0121] (Configuration of Motor Drivers 454, 456, 458, 460) The motor drivers 454, 456, 458, 460 are connected to the right front wheel motor 232, the left front wheel motor 242, the right rear wheel motor 486, and the left rear wheel motor 492 via the U-phase output terminal, the V-phase output terminal, and the W-phase output terminal. Further, the motor drivers 454, 456, 458, 460 are connected to the brake circuits 468, 470, 472, 474 via the brake circuit output terminal.

[0122] The motor drivers 454, 456, 458, 460 include a first switching element 454a, 456a, 458a, 460a, a second switching element 454b, 456b, 458b, 460b, a third switching element 454c, 456c, 458c, 460c, a fourth switching element 454d, 456d, 458d, 460d, a fifth switching element 454e, 456e, 458e, 460e, a sixth switching element 454f, 456f, 458f, 460f, a first diode 454g, 456g, 458g, 460g, a second diode 454h, 456h, 458h, 460h, and a third diode 454i, 456i, 458i, 460i. The first switching element 454a, 456a, 458a, 460a, the second switching element 454b, 456b, 458b, 460b, the third switching element 454c, 456c, 458c, 460c, the fourth switching element 454d, 456d, 458d, 460d, the fifth switching element 454e, 456e, 458e, 460e, and the sixth switching element 454f, 456f, 458f, 460f are, for example, field effect transistors, and specifically, n-channel MOSFETs having an insulated gate.

[0123] The drain of the first switching element 454a, 456a, 458a, 460a is connected to the source of the switching element 438a of the cutoff circuit 438, the source of the first switching element 454a, 456a, 458a, 460a is connected to the U-phase output terminal, and the gate of the first switching element 454a, 456a, 458a, 460a is connected to the motor MCUs 444, 446, 448, 450. The drain of the second switching element 454b, 456b, 458b, 460b is connected to the U-phase output terminal, the source of the second switching element 454b, 456b, 458b, 460b is connected to the ground potential, and the gate of the second switching element 454b, 456b, 458b, 460b is connected to the motor MCUs 444, 446, 448, 450.

[0124] The drains of the third switching elements 454c, 456c, 458c, 460c are connected to the source of the switching element 438a of the cutoff circuit 438. The sources of the third switching elements 454c, 456c, 458c, 460c are connected to the V-phase output terminal. The gates of the third switching elements 454c, 456c, 458c, 460c are connected to the motor MCUs 444, 446, 448, 450. The drains of the fourth switching elements 454d, 456d, 458d, 460d are connected to the V-phase output terminal. The sources of the fourth switching elements 454d, 456d, 458d, 460d are connected to the ground potential. The gates of the fourth switching elements 454d, 456d, 458d, 460d are connected to the motor MCUs 444, 446, 448, 450.

[0125] The drains of the fifth switching elements 454e, 456e, 458e, 460e are connected to the source of the switching element 438a of the cutoff circuit 438. The sources of the fifth switching elements 454e, 456e, 458e, 460e are connected to the W-phase output terminal. The gates of the fifth switching elements 454e, 456e, 458e, 460e are connected to the motor MCUs 444, 446, 448, 450. The drains of the sixth switching elements 454f, 456f, 458f, 460f are connected to the W-phase output terminal. The sources of the sixth switching elements 454f, 456f, 458f, 460f are connected to the ground potential. The gates of the sixth switching elements 454f, 456f, 458f, 460f are connected to the motor MCUs 444, 446, 448, 450.

[0126] The detection signals of the hall sensors 482, 484, 488, 494 of the right front wheel motor 232, the left front wheel motor 242, the right rear wheel motor 486, and the left rear wheel motor 492 are input to the motor MCUs 444, 446, 448, 450. According to the detection signals from the hall sensors 482, 484, 488, 494, the motor MCUs 444, 446, 448, 450 can switch the on / off states of the first switching elements 454a, 456a, 458a, 460a, the second switching elements 454b, 456b, 458b, 460b, the third switching elements 454c, 456c, 458c, 460c, the fourth switching elements 454d, 456d, 458d, 460d, the fifth switching elements 454e, 456e, 458e, 460e, and the sixth switching elements 454f, 456f, 458f, 460f, so as to operate the right front wheel motor 232, the left front wheel motor 242, the right rear wheel motor 486, and the left rear wheel motor 492 at a desired rotational speed. Further, the motor MCUs 444, 446, 448, 450 can brake the rotation of the right front wheel motor 232, the left front wheel motor 242, the right rear wheel motor 486, and the left rear wheel motor 492 by means of a so-called short-circuit brake by switching the second switching elements 454b, 456b, 458b, 460b, the fourth switching elements 454d, 456d, 458d, 460d, and the sixth switching elements 454f, 456f, 458f, 460f to the on state.

[0127] The anodes of the first diodes 454g, 456g, 458g, 460g are connected to the U-phase output terminals, and the cathodes of the first diodes 454g, 456g, 458g, 460g are connected to the brake circuit output terminals. The anodes of the second diodes 454h, 456h, 458h, 460h are connected to the V-phase output terminals, and the cathodes of the second diodes 454h, 456h, 458h, 460h are connected to the brake circuit output terminals. The anodes of the third diodes 454i, 456i, 458i, 460i are connected to the W-phase output terminals, and the cathodes of the third diodes 454i, 456i, 458i, 460i are connected to the brake circuit output terminals.

[0128] (Configuration of Brake Circuits 468, 470, 472, 474) Brake circuits 468, 470, 472, 474 include switching elements 468a, 470a, 472a, 472a, resistors 468b, 470b, 472b, 474b, amplifiers 468c, 470c, 472c, 474c, operational amplifiers 468d, 470d, 472d, 474d, and thermistors 468e, 470e, 472e, 474e.

[0129] Switching elements 468a, 470a, 472a, 472a are, for example, field effect transistors, specifically, n-channel MOSFETs having insulated gates. The drains of switching elements 468a, 470a, 472a, 472a are connected to the brake circuit output terminals of motor drivers 454, 456, 458, 460. The sources of switching elements 468a, 470a, 472a, 472a are connected to the ground potential via resistors 468b, 470b, 472b, 474b. The gates of switching elements 468a, 470a, 472a, 472a are connected to the output terminals of operational amplifiers 468d, 470d, 472d, 474d. Switching elements 468a, 470a, 472a, 472a can operate in a linear mode where the drain current varies substantially linearly as the gate voltage varies, and a switching mode where the drain current does not vary much even when the gate voltage varies, depending on the magnitude of the gate voltage.

[0130] Amplifiers 468c, 470c, 472c, and 474c detect the voltage between one end and the other end of resistors 468b, 470b, 472b, and 474b, amplify the detected voltage, and output it to the inverting input terminals of operational amplifiers 468d, 470d, 472d, and 474d. The non-inverting input terminals of operational amplifiers 468d, 470d, 472d, and 474d are connected to motor MCUs 444, 446, 448, and 450. Operational amplifiers 468d, 470d, 472d, and 474d apply a voltage corresponding to the difference between the current command value input from motor MCUs 444, 446, 448, and 450 to the non-inverting input terminals and the current detection value input from amplifiers 468c, 470c, 472c, and 474c to the inverting input terminals to the gates of switching elements 468a, 470a, 472a, and 472a. As a result, switching elements 468a, 470a, 472a, and 472a operate in a linear mode, and the operation of switching elements 468a, 470a, 472a, and 472a is controlled so that a current corresponding to the current command value from motor MCUs 444, 446, 448, and 450 flows through resistors 468b, 470b, 472b, and 474b. That is, the brake circuits 468, 470, 472, and 474 can be said to be linear regulators.

[0131] When the right front wheel motor 232, the left front wheel motor 242, the right rear wheel motor 486, and the left rear wheel motor 492 are rotating, if a large current flows from motor drivers 454, 456, 458, and 460 to brake circuits 468, 470, 472, and 474, a strong braking force acts on the right front wheel motor 232, the left front wheel motor 242, the right rear wheel motor 486, and the left rear wheel motor 492. For this reason, motor MCUs 444, 446, 448, and 450 can apply a large braking force to the right front wheel motor 232, the left front wheel motor 242, the right rear wheel motor 486, and the left rear wheel motor 492 by the brake circuits 468, 470, 472, and 474 during the rotation of the right front wheel motor 232, the left front wheel motor 242, the right rear wheel motor 486, and the left rear wheel motor 492.

[0132] When braking forces are applied to the right front wheel motor 232, the left front wheel motor 242, the right rear wheel motor 486, and the left rear wheel motor 492 by the brake circuits 468, 470, 472, 474, large currents flow through the switching elements 468a, 470a, 472a, 472a and the resistors 468b, 470b, 472b, 474b, so the temperature of the brake circuits 468, 470, 472, 474 rises due to heat generation. Therefore, when operating the brake circuits 468, 470, 472, 474, the motor MCUs 444, 446, 448, 450 drive the cooling fans 50d, 52d, 54d, 56d to cool the brake circuits 468, 470, 472, 474. Also, thermistors 468e, 470e, 472e, 474e are connected to the motor MCUs 444, 446, 448, 450. The thermistors 468e, 470e, 472e, 474e detect the temperature of the brake circuits 468, 470, 472, 474 and output it to the motor MCUs 444, 446, 448, 450.

[0133] Note that the brake circuits 468, 470, 472, 474 may be configured by preparing a plurality (for example, six) of sets of the switching elements 468a, 470a, 472a, 472a, the resistors 468b, 470b, 472b, 474b, the amplifiers 468c, 470c, 472c, 474c, the operational amplifiers 468d, 470d, 472d, 474d, and the thermistors 468e, 470e, 472e, 474e and connecting them in parallel with each other. By adopting such a configuration, a larger current can flow from the motor drivers 454, 456, 458, 460 through the brake circuits 468, 470, 472, 474, and larger braking forces can be applied to the right front wheel motor 232, the left front wheel motor 242, the right rear wheel motor 486, and the left rear wheel motor 492.

[0134] (Configuration of the cutoff circuit 440) As shown in FIG. 33, the cutoff circuit 440 includes a switching element 440a, a driver IC 440b, and an AND gate 440c. The switching element 440a is, for example, a field effect transistor, and specifically, an n-channel MOSFET having an insulated gate. The drain of the switching element 440a is connected to the battery potential (Vbat) output of the control power supply circuit 432, the source of the switching element 440a is connected to the electromagnetic brake drivers 464 and 466, and the gate of the switching element 440a is connected to the driver IC 440b. The first input terminal of the AND gate 440c is connected to the switching circuit 436, the second input terminal of the AND gate 440c is connected to the main MCU 434, and the output terminal of the AND gate 440c is connected to the driver IC 440b. The driver IC 440b turns on the switching element 440a when the output terminal of the AND gate 440c is at the H potential, that is, when both the first input terminal and the second input terminal of the AND gate 440c are at the H potential. The driver IC 440b turns off the switching element 440a when the output terminal of the AND gate 440c is at the L potential, that is, when one or both of the first input terminal and the second input terminal of the AND gate 440c are at the L potential.

[0135] (Configuration of Electromagnetic Brake Drivers 464 and 466) The electromagnetic brake drivers 464 and 466 are connected to the right rear wheel electromagnetic brake 490 and the left rear wheel electromagnetic brake 496 via the positive output terminal and the negative output terminal. The electromagnetic brake drivers 464 and 466 include switching elements 464a and 466a, and diodes 464b and 466b.

[0136] The switching elements 464a and 466a are, for example, field effect transistors, specifically, n-channel MOSFETs having insulated gates. The drains of the switching elements 464a and 466a are connected to the negative output terminal, the sources of the switching elements 464a and 466a are connected to the ground potential, and the gates of the switching elements 464a and 466a are connected to the motor MCUs 448 and 450. The anodes of the diodes 464b and 466b are connected to the negative output terminal, and the cathodes of the diodes 464b and 466b are connected to the positive output terminal.

[0137] When no voltage is applied between the positive output terminal and the negative output terminal, the right rear wheel electromagnetic brake 490 and the left rear wheel electromagnetic brake 496 apply a braking force to the right rear wheel motor 486 and the left rear wheel motor 492. When a voltage is applied between the positive output terminal and the negative output terminal, the braking force applied to the right rear wheel motor 486 and the left rear wheel motor 492 is released. When the switching element 440a of the cutoff circuit 440 is in the on state and the motor MCUs 448 and 450 turn on the switching elements 464a and 466a of the electromagnetic brake drivers 464 and 466, the battery voltage (Vbat) is applied between the positive output terminal and the negative output terminal, and the braking forces of the right rear wheel electromagnetic brake 490 and the left rear wheel electromagnetic brake 496 are released. The diodes 464b and 466b absorb the back surge from the right rear wheel electromagnetic brake 490 and the left rear wheel electromagnetic brake 496.

[0138] (Configuration of the cutoff circuit 442) As shown in FIG. 34, the cutoff circuit 442 includes a switching element 442a, a driver IC 442b, and an AND gate 442c. The switching element 442a is, for example, a field effect transistor, specifically, an n-channel MOSFET having an insulated gate. The drain of the switching element 442a is connected to the battery potential (Vbat) output of the control power supply circuit 432, the source of the switching element 442a is connected to the motor driver 462, and the gate of the switching element 442a is connected to the driver IC 442b. The first input terminal of the AND gate 442c is connected to the switching circuit 436, the second input terminal of the AND gate 442c is connected to the main MCU 434, and the output terminal of the AND gate 442c is connected to the driver IC 442b. The driver IC 442b turns on the switching element 442a when the output terminal of the AND gate 442c is at the H potential, that is, when both the first input terminal and the second input terminal of the AND gate 442c are at the H potential. The driver IC 442b turns off the switching element 442a when the output terminal of the AND gate 442c is at the L potential, that is, when one or both of the first input terminal and the second input terminal of the AND gate 442c are at the L potential.

[0139] (Configuration of Motor Driver 462) The motor driver 462 is connected to the steering motor 176 via a U-phase output terminal, a V-phase output terminal, and a W-phase output terminal. The motor driver 462 includes a first switching element 462a, a second switching element 462b, a third switching element 462c, a fourth switching element 462d, a fifth switching element 462e, and a sixth switching element 462f. The first switching element 462a, the second switching element 462b, the third switching element 462c, the fourth switching element 462d, the fifth switching element 462e, and the sixth switching element 462f are, for example, field effect transistors, specifically, n-channel MOSFETs having insulated gates.

[0140] The drain of the first switching element 462a is connected to the source of the switching element 442a of the cutoff circuit 442. The source of the first switching element 462a is connected to the U-phase output terminal, and the gate of the first switching element 462a is connected to the motor MCU 452. The drain of the second switching element 462b is connected to the U-phase output terminal, the source of the second switching element 462b is connected to the ground potential, and the gate of the second switching element 462b is connected to the motor MCU 452.

[0141] The drain of the third switching element 462c is connected to the source of the switching element 442a of the cutoff circuit 442. The source of the third switching element 462c is connected to the V-phase output terminal, and the gate of the third switching element 462c is connected to the motor MCU 452. The drain of the fourth switching element 462d is connected to the V-phase output terminal, the source of the fourth switching element 462d is connected to the ground potential, and the gate of the fourth switching element 462d is connected to the motor MCU 452.

[0142] The drain of the fifth switching element 462e is connected to the source of the switching element 442a of the cutoff circuit 442. The source of the fifth switching element 462e is connected to the W-phase output terminal, and the gate of the fifth switching element 462e is connected to the motor MCU 452. The drain of the sixth switching element 462f is connected to the W-phase output terminal, the source of the sixth switching element 462f is connected to the ground potential, and the gate of the sixth switching element 462f is connected to the motor MCU 452.

[0143] The detection signal of the hall sensor 480 of the steering motor 176 is input to the motor MCU 452. The motor MCU 452 can operate the steering motor 176 at a desired rotational speed by switching on / off the first switching element 462a, the second switching element 462b, the third switching element 462c, the fourth switching element 462d, the fifth switching element 462e, and the sixth switching element 462f according to the detection signal from the hall sensor 480. Further, the motor MCU 452 can brake the rotation of the steering motor 176 by means of a so-called short-circuit brake by switching on the second switching element 462b, the fourth switching element 462d, and the sixth switching element 462f.

[0144] (Processing performed by the main MCU 434) When the main power supply of the carrier 2 is turned on, the main MCU 434 executes the processing shown in FIGS. 35-37.

[0145] As shown in FIG. 35, in S2, the main MCU 434 sets the temperature protection flag to 0.

[0146] In S4, the main MCU 434 determines whether an overload is detected by any of the overload detection sensors 320a, 320b, 320c, and 320d. If an overload is detected (YES), the process proceeds to S6. In S6, the main MCU 434 sets the overload detection flag to 1. If no overload is detected in S4 (NO), the process proceeds to S8. In S8, the main MCU 434 sets the overload detection flag to 0. After S6 or S8, the process proceeds to S10.

[0147] In S10, the main MCU 434 determines whether a collision is detected by either of the collision detection switches 530 and 532. If a collision is detected (YES), the process proceeds to S12. In S12, the main MCU 434 sets the collision detection flag to 1. If no collision is detected in S10 (NO), the process proceeds to S14. In S14, the main MCU 434 sets the collision detection flag to 0. After S12 or S14, the process proceeds to S16.

[0148] In S16, the main MCU 434 determines whether the brake circuit temperature T detected by the thermistors 468e, 470e, 472e, and 474e exceeds the temperature protection threshold T1. If the brake circuit temperature T exceeds the temperature protection threshold T1 (YES), the process proceeds to S18. In S18, the main MCU 434 sets the temperature protection flag to 1. After S18, the process proceeds to S20. If the brake circuit temperature T does not exceed the temperature protection threshold T1 in S16 (NO), the process proceeds to S20.

[0149] In S20, the main MCU 434 determines whether the manual mode is selected by the mode changeover switch 98. If the manual mode is selected (YES), the process proceeds to S34 (see FIG. 36). If the manual mode is not selected (NO), the process proceeds to S22.

[0150] In S22, the main MCU 434 determines whether the automatic mode is selected by the mode changeover switch 98. If the automatic mode is selected (YES), the process proceeds to S72 (see FIG. 37). If the automatic mode is not selected (NO), the process proceeds to S24.

[0151] The process of S24 is executed when neither the manual mode nor the automatic mode is selected by the mode change switch 98, that is, when the parking mode is selected by the mode change switch 98. In S24, the main MCU 434 sets the target traveling speed V of the carrier 2 to 0 km / h and sets the target turning angle θ of the carrier 2 to 0°. In S26, the main MCU 434 sends a power-off prohibition signal to the cutoff circuits 438, 440, and 442.

[0152] In S28, the main MCU 434 calculates the rotational speed command values for the right front wheel motor 232, the left front wheel motor 242, the right rear wheel motor 486, and the left rear wheel motor 492, and the steering angle command value for the steering motor 176 from the target traveling speed V and the target turning angle θ.

[0153] In S30, the main MCU 434 sends the rotational speed command values for the right front wheel motor 232, the left front wheel motor 242, the right rear wheel motor 486, and the left rear wheel motor 492, and the steering angle command value for the steering motor 176 to the motor MCUs 444, 446, 448, 450, and 452.

[0154] In S32, the main MCU 434 receives the status signal from the motor MCUs 444, 446, 448, 450, and 452. After S32, the process returns to S2.

[0155] (Processing of the main MCU 434 in the manual mode) The process of S34 shown in FIG. 36 is executed when the manual mode is selected by the mode change switch 98. In S34, the main MCU 434 determines whether the trigger switch 100 is turned on based on the amount of depression of the trigger switch 100 input from the trigger switch 100. If the trigger switch 100 is turned on (YES), the process proceeds to S36. In S36, the main MCU 434 sends a power-on permission signal to the cutoff circuits 438, 440, and 442. After S36, the process proceeds to S46.

[0156] When the trigger switch 100 is not turned on at S34 (in the case of NO), the process proceeds to S38. At S38, the main MCU 434 sets the target traveling speed V of the carrier vehicle 2 to 0 km / h and sets the target turning angle θ of the carrier vehicle 2 to 0°.

[0157] At S40, the main MCU 434 sends a power-off prohibition signal to the cutoff circuits 438, 440, and 442.

[0158] At S42, the main MCU 434 determines whether the brake circuit temperature T detected by the thermistors 468e, 470e, 472e, and 474e is lower than the temperature protection release threshold value T2. When the brake circuit temperature T is lower than the temperature protection release threshold value T2 (in the case of YES), the process proceeds to S44. When the brake circuit temperature T is equal to or higher than the temperature protection release threshold value T2 at S42 (in the case of NO), the process proceeds to S28 (see FIG. 35).

[0159] The process of S44 is executed when the manual mode is selected by the mode changeover switch 98, the target traveling speed V of the carrier vehicle 2 is set to 0 km / h, a power-off prohibition signal is sent from the main MCU 434 to the cutoff circuits 438, 440, and 442 (that is, the carrier vehicle 2 is stopped), and the brake circuit temperature T is lower than the temperature protection release threshold value T2. At S44, the main MCU 434 sets the temperature protection flag to 0. After S44, the process proceeds to S28 (see FIG. 35).

[0160] At S46, the main MCU 434 determines whether forward movement is selected by the traveling direction changeover switch 102. When forward movement is selected (in the case of YES), the process proceeds to S48.

[0161] At S48, the main MCU 434 determines whether the collision detection flag is 0. When the collision detection flag is 0 (in the case of YES), the process proceeds to S50.

[0162] In S50, the main MCU 434 determines whether the overload detection flag is 0. If the collision detection flag is 0 (YES), the process proceeds to S52.

[0163] In S52, the main MCU 434 determines whether the temperature protection flag is 0. If the temperature protection flag is 0 (YES), the process proceeds to S54.

[0164] In S54, the main MCU 434 sets the upper limit traveling speed of the carrier 2 to the first upper limit traveling speed (for example, 5 km / h). After S54, the process proceeds to S58.

[0165] If the overload detection flag is 1 in S50 (NO) or the temperature protection flag is 1 in S52 (NO), the process proceeds to S56. In S56, the main MCU 434 sets the upper limit traveling speed of the carrier 2 to a second upper limit traveling speed (for example, 1 km / h) that is smaller than the first upper limit traveling speed. After S56, the process proceeds to S58.

[0166] In S58, the main MCU 434 specifies the target traveling speed V of the carrier 2 based on the amount of depression of the trigger switch 100 input from the trigger switch 100. At this time, if the target traveling speed V specified based on the amount of depression of the trigger switch 100 is equal to or higher than the upper limit traveling speed set in S54 and S56, the main MCU 434 makes the target traveling speed V match the upper limit traveling speed.

[0167] In S60, the main MCU 434 specifies the target turning angle θ of the carrier 2 based on the turning angle of the handle shaft 84 input from the rotation angle sensor 88. After S60, the process proceeds to S28 (see FIG. 35).

[0168] When the collision detection flag is 1 in S48 (in the case of NO), the process proceeds to S62. The process of S62 is executed when the manual mode is selected by the mode changeover switch 98, forward movement is selected by the traveling direction changeover switch 102, and the collision detection flag is 1. In S62, the main MCU 434 sets the target traveling speed V of the carrier vehicle 2 to 0 km / h and sets the target turning angle θ of the carrier vehicle 2 to 0°. In S64, the main MCU 434 sends a power-off prohibition signal to the cutoff circuits 438, 440, 442. After S64, the process proceeds to S28 (see FIG. 35).

[0169] When reverse movement is selected by the traveling direction changeover switch 102 in S46 (in the case of NO), the process proceeds to S66. The process of S66 is executed when the manual mode is selected by the mode changeover switch 98 and reverse movement is selected by the traveling direction changeover switch 102. In S66, the main MCU 434 sets the upper limit traveling speed of the carrier vehicle 2 to the second upper limit traveling speed (for example, 1 km / h).

[0170] In S68, the main MCU 434 specifies the target traveling speed V of the carrier vehicle 2 based on the amount of depression of the trigger switch 100 input from the trigger switch 100. At this time, when the target traveling speed V specified based on the amount of depression of the trigger switch 100 is equal to or higher than the upper limit traveling speed set in S66, the main MCU 434 makes the target traveling speed V coincide with the upper limit traveling speed.

[0171] In S70, the main MCU 434 specifies the target turning angle θ of the carrier vehicle 2 based on the turning angle of the handle shaft 84 input from the rotation angle sensor 88. After S70, the process proceeds to S28 (see FIG. 35).

[0172] Note that the upper limit traveling speed of the carrier vehicle 2 in the process of S54 may be appropriately changed according to the operation of the speed change switch 104. For example, when the traveling speed of the carrier vehicle 2 is set to high speed by the speed change switch 104, the upper limit traveling speed of the carrier vehicle 2 may be set to the first upper limit traveling speed (for example, 5 km / h). When the traveling speed of the carrier vehicle 2 is set to medium speed by the speed change switch 104, the traveling speed of the carrier vehicle 2 may be set to a third upper limit traveling speed (for example, 3 km / h) that is smaller than the first upper limit traveling speed and larger than the second upper limit traveling speed. When the traveling speed of the carrier vehicle 2 is set to low speed by the speed change switch 104, the traveling speed of the carrier vehicle 2 may be set to a fourth upper limit traveling speed (for example, 1.5 km / h) that is smaller than the third upper limit traveling speed and larger than the second upper limit traveling speed.

[0173] (Processing of the main MCU 434 in the automatic mode) The process of S72 shown in FIG. 37 is executed when the automatic mode is selected by the mode change switch 98. In S72, the main MCU 434 determines whether the collision detection flag is 0. If the collision detection flag is 0 (YES), the process proceeds to S74.

[0174] In S74, the main MCU 434 determines whether the overloading detection flag is 0. If the collision detection flag is 0 (YES), the process proceeds to S76.

[0175] In S76, the main MCU 434 sends an energization permission signal to the cutoff circuits 438, 440, 442.

[0176] In S78, the main MCU 434 determines whether the temperature protection flag is 0. If the temperature protection flag is 0 (YES), the process proceeds to S80. In S80, the main MCU 434 sets the upper limit traveling speed of the carrier vehicle 2 to the third upper limit traveling speed (for example, 3 km / h). After S80, the process proceeds to S84.

[0177] In S78, when the temperature protection flag is 1 (in the case of NO), the process proceeds to S82. In S82, the main MCU 434 sets the upper limit traveling speed of the carrier vehicle 2 to the second traveling speed (for example, 1 km / h). After S82, the process proceeds to S84.

[0178] In S84, the main MCU 434 specifies the target traveling speed V of the carrier vehicle 2 based on the command value from the automatic driving MCU 430. At this time, when the target traveling speed V specified based on the command value from the automatic driving MCU 430 is equal to or higher than the upper limit traveling speed set in S80 and S82, the main MCU 434 makes the target traveling speed V match the upper limit traveling speed.

[0179] In S86, the main MCU 434 specifies the target turning angle θ of the carrier vehicle 2 based on the command value from the automatic driving MCU 430. After S86, the process proceeds to S28 (see FIG. 35).

[0180] When the collision detection flag is 1 (in the case of NO) in S72 or when the overloading detection flag is 1 (in the case of NO) in S74, the process proceeds to S88. The process of S88 is executed when the automatic mode is selected by the mode changeover switch 98 and the collision detection flag is 1, or when the automatic mode is selected by the mode changeover switch 98 and the overloading detection flag is 1. In S88, the main MCU 434 sets the target traveling speed V of the carrier vehicle 2 to 0 km / h and sets the target turning angle θ of the carrier vehicle 2 to 0°. In S90, the main MCU 434 sends a power-off prohibition signal to the cutoff circuits 438, 440, and 442. After S90, the process proceeds to S28 (see FIG. 35).

[0181] (Processing performed by the motor MCUs 444 and 446) When the main power supply of the carrier vehicle 2 is turned on, the motor MCUs 444 and 446 execute the processes shown in FIGS. 38 and 39.

[0182] As shown in FIG. 38, in S102, the motor MCUs 444 and 446 receive a command signal from the main MCU 434.

[0183] In S104, the motor MCUs 444 and 446 specify the target rotational speeds RS1 of the right front wheel motor 232 and the left front wheel motor 242 based on the command signal received from the main MCU 434.

[0184] In S106, the motor MCUs 444 and 446 specify the current rotational speeds RS2 of the right front wheel motor 232 and the left front wheel motor 242 based on the detection signals received from the hall sensors 482 and 484.

[0185] In S108, the motor MCUs 444 and 446 determine whether the target rotational speed RS1 specified in S104 is greater than the current rotational speed RS2 specified in S106. If the target rotational speed RS1 is greater than the current rotational speed RS2 (YES), the process proceeds to S110.

[0186] In S110, the motor MCUs 444 and 446 perform PWM control on the right front wheel motor 232 and the left front wheel motor 242 by the motor drivers 454 and 456 to accelerate the rotation of the right front wheel motor 232 and the left front wheel motor 242. In addition, in S110, the motor MCUs 444 and 446 input 0 as the current command value to the brake circuits 468 and 470 to invalidate the operations of the brake circuits 468 and 470.

[0187] In S112, the motor MCUs 444 and 446 specify the target rotational acceleration RA1 based on the difference between the target rotational speed RS1 specified in S104 and the current rotational speed RS2 specified in S106.

[0188] In S114, the motor MCUs 444 and 446 specify the current rotational acceleration RA2 based on the detection signals received from the hall sensors 482 and 484.

[0189] In S116, the motor MCUs 444 and 446 determine whether the target rotational acceleration RA1 specified in S112 is greater than the current rotational acceleration RA2 specified in S114. If the target rotational acceleration RA1 is higher than the current rotational acceleration RA2 (YES), the process proceeds to S118. In S118, the motor MCUs 444 and 446 increase the duty ratio in the PWM control of the right front wheel motor 232 and the left front wheel motor 242 by the motor drivers 454 and 456. If in S116 the target rotational acceleration RA1 is less than or equal to the current rotational acceleration RA2 (NO), the process proceeds to S120. In S120, the motor MCUs 444 and 446 reduce the duty ratio in the PWM control of the right front wheel motor 232 and the left front wheel motor 242 by the motor drivers 454 and 456. After S118 or S120, the process proceeds to S134 (see FIG. 39).

[0190] If in S108 the target rotational speed RS1 is less than or equal to the current rotational speed RS2 (NO), the process proceeds to S122. In S122, the motor MCUs 444 and 446 decelerate the rotation of the right front wheel motors 232 and the left front wheel motors 242 via the brake circuits 468 and 470. Note that in S122, the motor MCUs 444 and 446 deactivate the operation of the motor drivers 454 and 456.

[0191] In S124, the motor MCUs 444 and 446 specify a target rotational deceleration RD1 based on the difference between the target rotational speed RS1 specified in S104 and the current rotational speed RS2 specified in S106.

[0192] In S126, the motor MCUs 444 and 446 specify the current rotational deceleration RD2 based on the detection signals received from the hall sensors 482 and 484.

[0193] In S128, the motor MCUs 444 and 446 determine whether the target rotational deceleration RD1 specified in S124 is lower than the current rotational deceleration RD2 specified in S126. If the target rotational deceleration RD1 is lower than the current rotational deceleration RD2 (YES), the process proceeds to S130. In S130, the motor MCUs 444 and 446 increase the current command value to the brake circuits 468 and 470. If in S128 the target rotational deceleration RD1 is less than or equal to the current rotational deceleration RD2 (NO), the process proceeds to S132. In S132, the motor MCUs 444 and 446 reduce the current command value to the brake circuits 468 and 470. After S130 or S132, the process proceeds to S134 (see FIG. 39).

[0194] As shown in FIG. 39, in S134, the motor MCUs 444 and 446 determine whether the brake circuit temperature T detected by the thermistors 468e and 470e exceeds the cooling start temperature T3. If the brake circuit temperature T exceeds the cooling start temperature T3 (YES), the process proceeds to S136. In S136, the motor MCUs 444 and 446 drive the cooling fans 50d and 52d to cool the electric brake circuit boards 50 and 52. After S136, the process proceeds to S138. If in S134 the brake circuit temperature T is less than or equal to the cooling start temperature T3 (NO), the process proceeds to S138.

[0195] In S138, the motor MCUs 444 and 446 determine whether the brake circuit temperature T detected by the thermistors 468e and 470e is lower than the cooling end temperature T4, which is lower than the cooling start temperature T3. If the brake circuit temperature T is lower than the cooling end temperature T4 (YES), the process proceeds to S140. In S140, the motor MCUs 444 and 446 stop the cooling fans 50d and 52d to end the cooling of the electric brake circuit boards 50 and 52. After S140, the process proceeds to S142. If in S138 the brake circuit temperature T is greater than or equal to the cooling end temperature T4 (NO), the process proceeds to S142.

[0196] In S142, the motor MCUs 444 and 446 send status signals to the main MCU 434. After S142, the process returns to S102 (see FIG. 38).

[0197] As described above, the motor MCUs 444 and 446 drive the cooling fans 50d and 52d to cool the electric brake circuit boards 50 and 52 based on the brake circuit temperature T detected by the thermistors 468e and 470e. With such a configuration, the motor MCUs 444 and 446 can continuously brake the right front wheel motor 232 and the left front wheel motor 242 by the brake circuits 468 and 470 over a long period of time. For example, the motor MCUs 444 and 446 can continuously brake the right front wheel motor 232 and the left front wheel motor 242 by the brake circuits 468 and 470 for 15 minutes or more, specifically 30 minutes or more, and more specifically 1 hour or more.

[0198] (Processing performed by the motor MCUs 448 and 450) When the main power supply of the transport vehicle 2 is turned on, the motor MCUs 448 and 450 execute the processing shown in FIGS. 40 and 41.

[0199] As shown in FIG. 40, in S152, the motor MCUs 448 and 450 receive a command signal from the main MCU 434.

[0200] In S154, the motor MCUs 448 and 450 specify the target rotational speed RS1 of the right rear wheel motor 486 and the left rear wheel motor 492 based on the command signal received from the main MCU 434.

[0201] In S156, the motor MCUs 448 and 450 specify the current rotational speed RS2 of the right rear wheel motor 486 and the left rear wheel motor 492 based on the detection signals received from the hall sensors 488 and 494.

[0202] In S158, the motor MCUs 448 and 450 determine whether the target rotation speed RS1 specified in S154 is equal to or higher than the lower limit rotation speed RS0. If the target rotation speed RS1 is equal to or higher than the lower limit rotation speed RS0 (YES), the process proceeds to S160. In S160, the motor MCUs 448 and 450 turn off the right rear wheel electromagnetic brake 490 and the left rear wheel electromagnetic brake 496 via the electromagnetic brake drivers 464 and 466. After S160, the process proceeds to S162. If the target rotation speed RS1 is lower than the lower limit rotation speed RS0 (NO), the process proceeds to S162.

[0203] In S162, the motor MCUs 448 and 450 determine whether the current rotation speed RS2 specified in S156 is equal to or lower than the lower limit rotation speed RS0. If the current rotation speed RS2 is equal to or lower than the lower limit rotation speed RS0 (YES), the process proceeds to S164. In S164, the motor MCUs 448 and 450 turn on the right rear wheel electromagnetic brake 490 and the left rear wheel electromagnetic brake 496 via the electromagnetic brake drivers 464 and 466. After S164, the process proceeds to S192 (see FIG. 41). If the current rotation speed RS2 is higher than the lower limit rotation speed RS0 (NO), the process proceeds to S166.

[0204] In S166, the motor MCUs 448 and 450 determine whether the target rotation speed RS1 specified in S154 is greater than the current rotation speed RS2 specified in S156. If the target rotation speed RS1 is greater than the current rotation speed RS2 (YES), the process proceeds to S168.

[0205] In S168, the motor MCUs 448 and 450 perform PWM control on the right rear wheel motor 486 and the left rear wheel motor 492 by the motor drivers 458 and 460 to accelerate the rotation of the right rear wheel motor 486 and the left rear wheel motor 492. In addition, in S168, the motor MCUs 448 and 450 input 0 as the current command value to the brake circuits 472 and 474 to invalidate the operations of the brake circuits 472 and 474.

[0206] In S170, the motor MCUs 448 and 450 specify a target rotational acceleration RA1 based on the difference between the target rotational speed RS1 specified in S154 and the current rotational speed RS2 specified in S156.

[0207] In S172, the motor MCUs 448 and 450 specify the current rotational acceleration RA2 based on the detection signals received from the hall sensors 488 and 494.

[0208] In S174, the motor MCUs 448 and 450 determine whether the target rotational acceleration RA1 specified in S170 is greater than the current rotational acceleration RA2 specified in S172. If the target rotational acceleration RA1 is higher than the current rotational acceleration RA2 (YES), the process proceeds to S176. In S176, the motor MCUs 448 and 450 increase the duty ratio in the PWM control of the right rear wheel motor 486 and the left rear wheel motor 492 by the motor drivers 458 and 460. If the target rotational acceleration RA1 is less than or equal to the current rotational acceleration RA2 in S174 (NO), the process proceeds to S178. In S178, the motor MCUs 448 and 450 reduce the duty ratio in the PWM control of the right rear wheel motor 486 and the left rear wheel motor 492 by the motor drivers 458 and 460. After S176 or S178, the process proceeds to S192 (see FIG. 41).

[0209] If the target rotational speed RS1 is less than or equal to the current rotational speed RS2 in S166 (NO), the process proceeds to S180. In S180, the motor MCUs 448 and 450 decelerate the rotation of the right rear wheel motors 486 and the left rear wheel motors 492 via the brake circuits 472 and 474. Note that in S180, the motor MCUs 448 and 450 deactivate the operation of the motor drivers 458 and 460.

[0210] In S182, the motor MCUs 448 and 450 specify a target rotational deceleration RD1 based on the difference between the target rotational speed RS1 specified in S154 and the current rotational speed RS2 specified in S156.

[0211] In S184, the motor MCUs 448 and 450 identify the current rotational deceleration RD2 based on the detection signals received from the Hall sensors 488 and 494.

[0212] In S186, the motor MCUs 448 and 450 determine whether the target rotational deceleration RD1 identified in S182 is lower than the current rotational deceleration RD2 identified in S184. If the target rotational deceleration RD1 is lower than the current rotational deceleration RD2 (YES), the process proceeds to S188. In S188, the motor MCUs 448 and 450 increase the current command value to the brake circuits 472 and 474. If in S186 the target rotational deceleration RD1 is less than or equal to the current rotational deceleration RD2 (NO), the process proceeds to S190. In S190, the motor MCUs 448 and 450 reduce the current command value to the brake circuits 472 and 474. After S188 or S190, the process proceeds to S192 (see FIG. 41).

[0213] As shown in FIG. 41, in S192, the motor MCUs 448 and 450 determine whether the brake circuit temperature T detected by the thermistors 472e and 474e exceeds the cooling start temperature T3. If the brake circuit temperature T exceeds the cooling start temperature T3 (YES), the process proceeds to S194. In S194, the motor MCUs 448 and 450 drive the cooling fans 54d and 56d to cool the electric brake circuit boards 54 and 56. After S194, the process proceeds to S196. If in S192 the brake circuit temperature T is below the cooling start temperature T3 (NO), the process proceeds to S196.

[0214] In S196, the motor MCUs 448 and 450 determine whether the brake circuit temperature T detected by the thermistors 472e and 474e is below the cooling end temperature T4. If the brake circuit temperature T is below the cooling end temperature T4 (YES), the process proceeds to S198. In S198, the motor MCUs 448 and 450 stop the cooling fans 54d and 56d to end the cooling of the electric brake circuit boards 54 and 56. After S198, the process proceeds to S200. If in S196 the brake circuit temperature T is above or equal to the cooling end temperature T4 (NO), the process proceeds to S200.

[0215] In S200, the motor MCUs 448 and 450 send status signals to the main MCU 434. After S200, the process returns to S152 (see FIG. 40).

[0216] FIG. 42 shows an example of the change over time in the traveling speed, braking current, and braking circuit temperature when the carrier 2 travels on flat ground and downhill in manual mode. In the example shown in FIG. 42, the manual mode is selected by the mode changeover switch 98, and forward movement is selected by the forward / backward changeover switch. When the trigger switch 100 is switched from off to on at time t1, the right rear wheel electromagnetic brake 490 and the left rear wheel electromagnetic brake 496 are released by the electromagnetic brake drivers 464, 466, and the motor drivers 454, 456, 458, 460 drive the right front wheel motor 232, the left front wheel motor 242, the right rear wheel motor 486, and the left rear wheel motor 492, and the carrier 2 starts moving forward. When the traveling speed of the carrier 2 reaches the first upper limit traveling speed at time t2, the braking circuits 468, 470, 472, 474 are activated and an electric brake is applied to the right front wheel motor 232, the left front wheel motor 242, the right rear wheel motor 486, and the left rear wheel motor 492. Even when the carrier 2 moves from flat ground to downhill, the traveling speed of the carrier 2 is maintained at the first upper limit traveling speed by the activation of the braking circuits 468, 470, 472, 474. Also, when the braking circuits 468, 470, 472, 474 are activated, the temperature of the braking circuits 468, 470, 472, 474 rises. When the temperature of the braking circuits 468, 470, 472, 474 exceeds the temperature protection threshold value T1 at time t3, the upper limit traveling speed of the carrier 2 is switched from the first upper limit traveling speed to the second upper limit traveling speed, and the braking circuits 468, 470, 472, 474 apply a stronger electric brake to the right front wheel motor 232, the left front wheel motor 242, the right rear wheel motor 486, and the left rear wheel motor 492. As a result, although the traveling speed of the carrier 2 decreases, the temperature of the braking circuits 468, 470, 472, 474 rises more steeply. When the traveling speed of the carrier 2 decreases to the second upper limit traveling speed at time t4, the electric brake applied to the right front wheel motor 232, the left front wheel motor 242, the right rear wheel motor 486, and the left rear wheel motor 492 by the braking circuits 468, 470, 472, 474 weakens, and the temperature of the braking circuits 468, 470, 472, 474 decreases.Even if the temperatures of the brake circuits 468, 470, 472, and 474 fall below the temperature protection threshold value T1 and further below the temperature protection release threshold value T2, the temperature protection is not released until the carrier vehicle 2 stops, and the upper limit traveling speed of the carrier vehicle 2 remains at the second upper limit traveling speed. When the trigger switch 100 switches from on to off at time t5, strong electric brakes are applied to the right front wheel motor 232, the left front wheel motor 242, the right rear wheel motor 486, and the left rear wheel motor 492 by the brake circuits 468, 470, 472, and 474. When the carrier vehicle 2 stops at time t6, the temperature protection is released, and the upper limit traveling speed of the carrier vehicle 2 switches from the second upper limit traveling speed to the first upper limit traveling speed. Also, when the carrier vehicle 2 stops at time t6, the electric brake by the brake circuits 468, 470, 472, and 474 ends, and a short-circuit brake by the motor drivers 454, 456, 458, and 460 is applied to the right front wheel motor 232, the left front wheel motor 242, the right rear wheel motor 486, and the left rear wheel motor 492, and then the right rear wheel 252 and the left rear wheel 272 are locked by the right rear wheel electromagnetic brake 490 and the left rear wheel electromagnetic brake 496. After the electric brake by the brake circuits 468, 470, 472, and 474 ends, the temperature of the brake circuits 468, 470, 472, and 474 decreases. Then, when the trigger switch 100 switches from off to on again at time t7, the right rear wheel electromagnetic brake 490 and the left rear wheel electromagnetic brake 496 are released by the electromagnetic brake drivers 464 and 466, and the motor drivers 454, 456, 458, and 460 drive the right front wheel motor 232, the left front wheel motor 242, the right rear wheel motor 486, and the left rear wheel motor 492, and the carrier vehicle 2 starts to move forward. When the traveling speed of the carrier vehicle 2 reaches the first upper limit traveling speed at time t8, the brake circuits 468, 470, 472, and 474 operate to apply an electric brake to the right front wheel motor 232, the left front wheel motor 242, the right rear wheel motor 486, and the left rear wheel motor 492.

[0217] (Processing performed by the motor MCU 452) When the main power supply of the carrier vehicle 2 is turned on, the motor MCU 452 executes the processing shown in FIG. 43.

[0218] In S202, the motor MCU 452 receives a command signal from the main MCU 434.

[0219] In S204, the motor MCU 452 determines the target steering angle δ of the steering unit 10 based on the command signal received from the main MCU 434.

[0220] In S206, the motor MCU 452 determines the current steering angle γ of the steering unit 10 based on the detection signal received from the steering angle sensor 166.

[0221] In S208, the motor MCU 452 determines whether the target steering angle δ specified in S204 matches the current steering angle γ specified in S206. If the target steering angle δ and the current steering angle γ do not match (NO), the process proceeds to S210.

[0222] In S210, the motor MCU 452 determines the target rotational speed PR1 of the steering motor 176 based on the difference between the target steering angle δ specified in S204 and the current steering angle γ specified in S206.

[0223] In S212, the motor MCU 452 drives the steering motor 176 by PWM control via the motor driver 462 so that the steering motor 176 rotates at the target rotational speed PR1 specified in S210. After S212, the process proceeds to S216.

[0224] If the target steering angle δ and the current steering angle γ match in S208 (YES), the process proceeds to S214. In S214, the motor MCU 452 applies a short - circuit brake to the steering motor 176 via the motor driver 462. After S214, the process proceeds to S216.

[0225] In S216, the motor MCU 452 transmits a status signal to the main MCU 434. After S216, the process returns to S202.

[0226] (Variant example) In the above-described embodiment, the right front wheel motor 232, the left front wheel motor 242, the right rear wheel motor 486, and the left rear wheel motor 492 may be in-wheel motors (not shown) incorporated in the right front wheel 192, the left front wheel 212, the right rear wheel 252, and the left rear wheel 272, respectively.

[0227] In the above-described embodiment, the steering motor 176, the right front wheel motor 232, the left front wheel motor 242, the right rear wheel motor 486, and the left rear wheel motor 492 may be outer rotor type brushless DC motors, brushed DC motors, AC motors, or other types of motors.

[0228] In the above-described embodiment, instead of the hall sensors 482, 484, 488, 494, and 480, the motor MCUs 444, 446, 448, 450, and 452 may detect the rotational speeds of the right front wheel motor 232, the left front wheel motor 242, the right rear wheel motor 486, the left rear wheel motor 492, and the steering motor 176 using circuits that detect the induced voltages of the right front wheel motor 232, the left front wheel motor 242, the right rear wheel motor 486, the left rear wheel motor 492, and the steering motor 176.

[0229] In the above-described embodiment, instead of the front wheel unit 12 and the rear wheel unit 14, the transport vehicle 2 may be configured to be moved by a crawler unit including drive wheels and driven wheels arranged in a front-to-back manner, a belt stretched between the drive wheels and the driven wheels, and a motor for rotating the drive wheels.

[0230] In the above-described embodiment, instead of the steering motor 176, the steering unit 10 may be configured to rotate the steering shaft 168 using another type of actuator.

[0231] In the above-described embodiment, the bumper unit 16 is provided in front of the carrier 2, and the collision detection switches 530 and 532 detect a collision from the front of the carrier 2. Differently from this, the bumper unit 16 may be provided behind the carrier 2, and the collision detection switches 530 and 532 may be configured to detect a collision from behind the carrier 2. Alternatively, two bumper units 16 may be provided in front of and behind the carrier 2, respectively, and the collision detection switches 530 and 532 of each bumper unit 16 may be configured to detect a collision from the front and behind the carrier 2, respectively. When the bumper unit 16 is provided behind the carrier 2 and the collision detection switches 530 and 532 detect a collision from behind the carrier 2, when forward movement is selected in S46 of FIG. 36 (in the case of YES), the process proceeds to S50, and when backward movement is selected in S46 (in the case of NO), the process proceeds to S48. When the collision detection flag is 0 in S48 (in the case of YES), the process may proceed to S66, and when the collision detection flag is 1 in S48 (in the case of NO), the process may proceed to S62.

[0232] In the above-described embodiment, the handle unit 8 may include a movable cam member 90, a fixed cam member 92, a coil spring 94, and a cover member (not shown) that covers a part of the handle shaft 84. In this case, the fixing member 82 may constitute a part of the cover member.

[0233] In the above-described embodiment, the handle unit 8 may include another type of elastic member instead of the coil spring 94. Further, the handle unit 8 may include a damper (not shown) that applies a damping force to the rotation of the handle shaft 84.

[0234] In the above-described embodiments, the overload detection sensors 320a, 320b, 320c, 320d, 380 have been described as being photointerrupters. However, the overload detection sensors 320a, 320b, 320c, 320d, 380 may be photoreflectors that detect the presence or absence of light reflection by the detection units 348a, 348b, 348c, 348d, 416, may be magnetic sensors that detect magnetism from magnets provided in the detection units 348a, 348b, 348c, 348d, 416, or may be other types of non-contact detection sensors. Alternatively, the overload detection sensors 320a, 320b, 320c, 320d, 380 may be contact detection sensors.

[0235] In the above-described embodiments, the switching elements 468a, 470a, 472a, 472a of the brake circuits 468, 470, 472, 474 have been described as being n-channel MOSFETs. However, the switching elements 468a, 470a, 472a, 472a may be p-channel MOSFETs, may be IGBTs, may be bipolar transistors, or may be other types of transistors. Alternatively, the switching elements 468a, 470a, 472a, 472a may be other types of electronically variable resistance elements such as thyristors. The switching elements 468a, 470a, 472a, 472a may be composed of Si semiconductors, may be composed of SiC semiconductors, may be composed of GaN semiconductors, or may be composed of other types of semiconductors.

[0236] As described above, in one or more embodiments, the carrier vehicle 2 includes a right front wheel 192, a left front wheel 212, a right rear wheel 252, and a left rear wheel 272 (examples of drive wheels), a right front wheel motor 232, a left front wheel motor 242, a right rear wheel motor 486, and a left rear wheel motor 492 (examples of motors) for rotating the right front wheel 192, the left front wheel 212, the right rear wheel 252, and the left rear wheel 272, and motor drivers 454, 456, 458, 460 (examples of motor drive circuits) configured to drive the right front wheel motor 232, the left front wheel motor 242, the right rear wheel motor 486, and the left rear wheel motor 492, and a main MCU 434 and motor MCUs 444, 446, 448, 450 (examples of control units) configured to control the right front wheel motor 232, the left front wheel motor 242, the right rear wheel motor 486, and the left rear wheel motor 492 via the motor drivers 454, 456, 458, 460 so that the traveling speed of the carrier vehicle 2 is equal to or lower than the upper limit traveling speed. The carrier vehicle 2 is provided with a trigger switch 100 (example of an operation member) that receives an operation by the user. When the trigger switch 100 is on, the right front wheel motor 232, the left front wheel motor 242, the right rear wheel motor 486, and the left rear wheel motor 492 are driven, and when the trigger switch 100 is off, the right front wheel motor 232, the left front wheel motor 242, the right rear wheel motor 486, and the left rear wheel motor 492 stop. The carrier vehicle 2 can operate in a manual mode and an automatic mode. In the automatic mode, the upper limit traveling speed (for example, 3 km / h) is set lower than the upper limit traveling speed (for example, 5 km / h) in the manual mode.

[0237] According to the above configuration, since the upper limit traveling speed when the carrier vehicle 2 operates in the automatic mode is set lower than the upper limit traveling speed when the carrier vehicle 2 operates in the manual mode, the safety when the carrier vehicle 2 operates in the automatic mode can be further enhanced.

[0238] In one or more embodiments, the transport vehicle 2 further includes overload detection sensors 320a, 320b, 320c, 320d for detecting overloading of the load. In the automatic mode, when overloading is detected by the overload detection sensors 320a, 320b, 320c, 320d, the running of the transport vehicle 2 is prohibited. In the manual mode, even if overloading is detected by the overload detection sensors 320a, 320b, 320c, 320d, the running of the transport vehicle 2 is allowed.

[0239] According to the above configuration, in the manual mode, the running of the transport vehicle 2 is allowed even if overloading is detected, and in the automatic mode, the running of the transport vehicle 2 is prohibited when overloading is detected. Therefore, the safety of the transport vehicle 2 when operating in the automatic mode can be further improved.

[0240] In one or more embodiments, the transport vehicle 2 further includes collision detection switches 530, 532 (examples of collision detection sensors) for detecting a collision from the front to the transport vehicle 2. In the automatic mode, when the transport vehicle 2 is moving backward and a collision is detected by the collision detection switches 530, 532, the running of the transport vehicle 2 is prohibited. In the manual mode, when the transport vehicle 2 is moving backward and a collision is detected by the collision detection switches 530, 532, the running of the transport vehicle 2 is allowed.

[0241] According to the above configuration, in the manual mode, the running of the transport vehicle 2 is allowed even if a collision from the front of the transport vehicle 2 is detected when the transport vehicle 2 is moving backward, and in the automatic mode, the running of the transport vehicle 2 is prohibited when a collision from the front of the transport vehicle 2 is detected when the transport vehicle 2 is moving backward. Therefore, the safety of the transport vehicle 2 when operating in the automatic mode can be further improved.

[0242] In one or more embodiments, the carrier vehicle 2 further includes collision detection switches 530, 532 (examples of collision detection sensors) that detect a rear collision to the carrier vehicle 2. In the automatic mode, when the carrier vehicle 2 is moving forward and a collision is detected by the collision detection switches 530, 532, the running of the carrier vehicle 2 is prohibited. In the manual mode, when the carrier vehicle 2 is moving forward, even if a collision is detected by the collision detection switches 530, 532, the running of the carrier vehicle 2 is permitted.

[0243] According to the above configuration, in the manual mode, even if a rear collision to the carrier vehicle 2 is detected when the carrier vehicle 2 is moving forward, the running of the carrier vehicle 2 is permitted, and in the automatic mode, when a rear collision to the carrier vehicle 2 is detected when the carrier vehicle 2 is moving forward, the running of the carrier vehicle 2 is prohibited, so that the safety when the carrier vehicle 2 operates in the automatic mode can be further enhanced.

[0244] In one or more embodiments, the carrier vehicle 2 is capable of performing a follow-up operation of moving by tracking a beacon carried by a user and a remote control operation of moving according to an instruction from a remote control operated by the user in the automatic mode.

[0245] According to the above configuration, the safety when the carrier vehicle 2 performs the follow-up operation and the remote control operation in the automatic mode can be further enhanced.

Description of Reference Numerals

[0246] 2: Carrier vehicle 4: Chassis unit 6: Loading platform unit 8: Handle unit 10: Steering unit 11: Suspension mechanism 12: Front wheel unit 12a: Right front wheel unit 12b: Left front wheel unit 14: Rear wheel unit 14a: Right rear wheel unit 14b: Left rear wheel unit 16: Bumper unit 20: Base plate 20a: Through hole 20b: Through hole 20c: Through hole 20d: Through hole 22: Front support member 22a: Upper right connecting part 22b: Lower right connecting part 22c: Upper left connecting part 22d: Lower left connecting part 24: Rear support member 26: Lower right frame 28: Lower left frame 30: Upper right frame 32: Upper left frame 34: Battery box 36: Lower controller case 38: Battery pack 40: Battery mounting part 42: Battery cover 44: Main control circuit board 44a: Circuit board case 46: Drive control circuit board 46a: Circuit board case 48: Drive control circuit board 48a: Circuit board case 50: Electric brake circuit board 50a: Heat dissipation case 50b: Circuit board housing part 50c: Heat dissipation fins 50d: Cooling fan 52: Electric brake circuit board 52a: Heat dissipation case 52b: Circuit board housing part 52c: Heat dissipation fins 52d: Cooling fan 54: Electric brake circuit board 54a: Heat dissipation case 54b: Circuit board housing part 54c: Heat dissipation fins 54d: Cooling fan 56: Electric brake circuit board 56a: Heat dissipation case 56b: Circuit board housing part 56c: Heat dissipation fin 56d: Cooling fan 58: Heat dissipation plate 60: Main frame 62: Right guard 64: Left guard 66: Front guard 70: Switch box 72: Right handle 72a: Support part 72b: Handle part 72c: Right grip 73: Steering handle 74: Left handle 74a: Support part 74b: Handle part 74c: Left grip 76: Handle arm 78: Support pipe 80: Clamp member 80a: Clamp piece 80b: Clamp piece 80c: Fastening part 82: Fixing member 84: Handle shaft 84a: Guide projection 86: Base member 88: Rotation angle sensor 90: Movable cam member 90a: Cam convex part 90b: Cam convex part 90c: First cam surface 90d: First cam surface 90e: Second cam surface 90f: Second cam surface 90g: Guide groove 90h: Spring receiving part 92: Fixed cam member 92a: Cylindrical part 92b: Flange part 92c: Cam recess 92d: Cam recess 92e: First cam surface 92f: First cam surface 92g: Second cam surface 92h: Second cam surface 92i: Stopper portion 92j: Stopper portion 94: Coil spring 96: Main power switch 98: Mode changeover switch 98a: Ground terminal 98b: Manual mode terminal 98c: Automatic mode terminal 100: Trigger switch 100a: Ground terminal 100b: Trigger terminal 100c: Variable resistor 102: Travel direction changeover switch 102a: Ground terminal 102b: Travel direction terminal 104: Speed changeover switch 106: Siren switch 160: Motor housing 162: Motor support member 164: Gear housing 166: Steering angle sensor 168: Steering shaft 168a: Gear portion 169: Transmission mechanism 170: Steering plate 172: Right tie rod 174: Left tie rod 176: Steering motor 176a: Motor shaft 176b: Gear portion 178: Spindle 178a: Spring receiving portion 180: Cam wheel 180a: Cam groove 181: Torque limiter 182: Movable gear 182a: Gear part 182b: Concave part 182c: Cam projection 184: Coil spring 186: Cylindrical worm 188: Worm wheel 190: Relay shaft 190a: Gear part 192: Right front wheel 192a: Right front wheel axle 194: Right side gear housing 195: Right side holding member 196: Right side motor housing 198: Right side kingpin 200: Right side sleeve 202: Upper right arm 204: Lower right arm 206: Right side buffer member 206a: Damper 206b: Coil spring 208: Right side steering plate 212: Left front wheel 212a: Left side axle 214: Left side gear housing 215: Left side holding member 216: Left side motor housing 218: Left side kingpin 220: Left side sleeve 222: Upper left arm 224: Lower left arm 226: Left side buffer member 226a: Damper 226b: Coil spring 228: Left side steering plate 232: Right front wheel motor 232a: Right front wheel motor shaft 234: Planetary gear mechanism 242: Left front wheel motor 242a: Left front wheel motor shaft 244: Planetary gear mechanism 252: Right rear wheel 254: Right gear housing 254a: Connecting part 256: Right motor housing 258: Right brake housing 260: Right clutch lever 264: Right buffer member 264a: Damper 264b: Coil spring 272: Left rear wheel 274: Left gear housing 274a: Connecting part 276: Left motor housing 278: Left brake housing 280: Left clutch lever 284: Left buffer member 284a: Damper 284b: Coil spring 302: Overload detection mechanism 302a: Right front overload detection mechanism 302b: Left front overload detection mechanism 302c: Right rear overload detection mechanism 302d: Left rear overload detection mechanism 304: Emergency stop switch case 306: Upper controller case 308: Emergency stop switch 308a: Grounding terminal 308b: Emergency stop terminal 312: Upper controller case 312a: Pillar member 312b: Pillar member 312c: Pillar member 312d: Pillar member 314a: Coil spring 314b: Coil spring 314c: Coil spring 314d: Coil spring 316a: Detection plate 316b: Detection plate 316c: Detection plate 316d: Detection Plate 318a: Base Member 318b: Base Member 318c: Base Member 318d: Base Member 320a: Overload Detection Sensor 320b: Overload Detection Sensor 320c: Overload Detection Sensor 320d: Overload Detection Sensor 322a: Cylindrical Portion 322b: Cylindrical Portion 322c: Cylindrical Portion 322d: Cylindrical Portion 324a: Flange Portion 324b: Flange Portion 324c: Flange Portion 324d: Flange Portion 326a: Upper Small-Diameter Portion 326b: Upper Small-Diameter Portion 326c: Upper Small-Diameter Portion 326d: Upper Small-Diameter Portion 328a: Lower Small-Diameter Portion 328b: Lower Small-Diameter Portion 328c: Lower Small-Diameter Portion 328d: Lower Small-Diameter Portion 330a: Through-Hole 330b: Through-Hole 330c: Through-Hole 330d: Through-Hole 332a: Threaded Hole 332b: Threaded Hole 332c: Threaded Hole 332d: Threaded Hole 334a: Washer 334b: Washer 334c: Washer 334d: Washer 336a: Bolt 336b: Bolt 336c: Bolt 336d: Bolt 338a: Through-Hole 338b: Through-Hole 338c: Through-hole 338d: Through-hole 340a: Washer 340b: Washer 340c: Washer 340d: Washer 342a: Threaded hole 342b: Threaded hole 342c: Threaded hole 342d: Threaded hole 344a: Bolt 344b: Bolt 344c: Bolt 344d: Bolt 346a: Support part 346b: Support part 346c: Support part 346d: Support part 348a: Detection part 348b: Detection part 348c: Detection part 348d: Detection part 350a: Engagement part 350b: Engagement part 350c: Engagement part 350d: Engagement part 352a: Nut part 352b: Nut part 352c: Nut part 352d: Nut part 354a: Guide part 354b: Guide part 354c: Guide part 354d: Guide part 356a: Sensor holding part 356b: Sensor holding part 356c: Sensor holding part 356d: Sensor holding part 358a: Bolt 358b: Bolt 358c: Bolt 358d: Bolt 360a: Light-emitting element 360b: Light-emitting element 360c: Light-emitting element 360d: Light-emitting element 362a: Light-receiving element 362b: Light-receiving element 362c: Light-receiving element 362d: Light-receiving element 364: Overload detection mechanism 366: Support member 368: Pillar member 370: Coil spring 372: Detection plate 374: Upper housing 376: Sensor holding member 378: Lower housing 380: Overload detection sensor 382: Cap 384: Cylindrical part 386: Upper small-diameter part 388: Lower small-diameter part 390: Through hole 392: Threaded hole 394: Washer 396: Washer 398: Bolt 400: Accommodation chamber 402: Bottom wall 404: Through hole 406: Seal member 408: Cushion 410: Threaded hole 412: Bolt 414: Support part 416: Detection part 418: Guide part 420: Light-emitting element 422: Light-receiving element 424: Accommodation space 426: Automatic driving control circuit board 428: Wireless I / F 430: Automatic driving MCU 432: Control power circuit 434: Main MCU 436: Switching circuit 438: Interrupt circuit 438a: Switching element 438b: Driver IC 438c: AND gate 440: Cut-off circuit 440a: Switching element 440b: Driver IC 440c: AND gate 442: Cut-off circuit 442a: Switching element 442b: Driver IC 442c: AND gate 446: Motor MCU 448: Motor MCU 450: Motor MCU 452: Motor MCU 454: Motor driver 454a: First switching element 454b: Second switching element 454c: Third switching element 454d: Fourth switching element 454e: Fifth switching element 454f: Sixth switching element 454g: First diode 454h: Second diode 454i: Third diode 456: Motor driver 456a: First switching element 456b: Second switching element 456c: Third switching element 456d: Fourth switching element 456e: Fifth switching element 456f: Sixth switching element 456g: First diode 456h: Second diode 456i: Third diode 458: Motor driver 458a: First switching element 458b: Second switching element 458c: Third switching element 458d: Fourth switching element 458e: Fifth switching element 458f: Sixth switching element 458g: First diode 458h: Second diode 458i: Third diode 460: Motor driver 460a: First switching element 460b: Second switching element 460c: Third switching element 460d: Fourth switching element 460e: Fifth switching element 460f: Sixth switching element 460g: First diode 460h: Second diode 460i: Third diode 462: Motor driver 462a: First switching element 462b: Second switching element 462c: Third switching element 462d: Fourth switching element 462e: Fifth switching element 462f: Sixth switching element 464: Electromagnetic brake driver 464a: Switching element 464b: Diode 466: Electromagnetic brake driver 466a: Switching element 466b: Diode 468: Brake circuit 468a: Switching element 468b: Resistor 468c: Amplifier 468d: Operational amplifier 468e: Thermistor 470: Brake Circuit 470a: Switching Element 470b: Resistor 470c: Amplifier 470d: Operational Amplifier 470e: Thermistor 472: Brake Circuit 472a: Switching Element 472b: Resistor 472c: Amplifier 472d: Operational Amplifier 472e: Thermistor 474: Brake Circuit 474b: Resistor 474c: Amplifier 474d: Operational Amplifier 474e: Thermistor 476: LED 478: Buzzer 480: Hall Sensor 482: Hall Sensor 484: Hall Sensor 486: Right Rear Wheel Motor 488: Hall Sensor 490: Right Rear Wheel Electromagnetic Brake 492: Left Rear Wheel Motor 494: Hall Sensor 496: Left Rear Wheel Electromagnetic Brake 500: Base Member 502: Housing 502a: Accommodation Portion 502b: Right Support Portion 502c: Left Support Portion 504: Right Headlight 506: Left Headlight 508: Bumper Frame 510: Bumper Support Member 512: Bumper Support Member 514: Linear Pipe 514a: Long Hole 514b: Long Hole 516: Linear Pipe 516a: Long Hole 516b: Long hole 518: Coil spring 520: Coil spring 522: Linear bearing 524: Linear bearing 526: Contact plate 526a: Contact portion 528: Contact plate 528a: Contact portion 530: Collision detection switch 530a: Grounding terminal 530b: Collision detection terminal 532: Collision detection switch 532a: Grounding terminal 532b: Collision detection terminal 534a: Bolt 534b: Bolt 536a: Nut 536b: Nut 538a: Bolt 538b: Bolt 540a: Nut 540b: Nut 542: Cancellation circuit 542a: Transistor 542b: Resistor 542c: Resistor 542d: Resistor 544: Cancellation circuit 544a: Transistor 544b: Resistor 544c: Resistor 544d: Resistor 546: Cancellation circuit 546a: Transistor 546b: Resistor 546c: Resistor 546d: Resistor 548: Delay circuit 548a: Diode 548b: Resistor 548c: Capacitor 548d: Buffer gate 550: AND Gate 552: AND Gate 554: OR Gate 556: OR Gate 558: NOT Gate 560: NOT Gate 562: NOT Gate 564: NOT Gate 566: NOT Gate 568: Resistor 570: Resistor 572: Resistor 574: Resistor 576: Resistor 578: Resistor

Claims

1. A transport vehicle, driving wheels, a motor for rotating the driving wheels, a motor drive circuit configured to drive the motor, a control unit configured to control the motor via the motor drive circuit so that the traveling speed of the transport vehicle is equal to or lower than the upper limit traveling speed, an operation member provided on the transport vehicle and accepting an operation by a user, comprising an overload detection sensor for detecting overloading of a load, operable in a manual mode in which the motor is driven when the operation member is on and the motor stops when the operation member is off, and an automatic mode in which the motor is driven regardless of on / off of the operation member, the upper limit traveling speed in the automatic mode is set lower than the upper limit traveling speed in the manual mode, in the automatic mode, when overloading is detected by the overload detection sensor, traveling of the transport vehicle is prohibited, in the manual mode, when overloading is detected by the overload detection sensor, traveling of the transport vehicle is permitted in a state where the upper limit traveling speed is reduced compared to when overloading is not detected. A transport vehicle.

2. further comprising a collision detection sensor for detecting a collision from the front to the transport vehicle, in the automatic mode, when a collision is detected by the collision detection sensor while the transport vehicle is moving backward, traveling of the transport vehicle is prohibited, the transport vehicle according to claim 1, wherein in the manual mode, when a collision is detected by the collision detection sensor while the transport vehicle is moving backward, traveling of the transport vehicle is permitted.

3. further comprising a collision detection sensor for detecting a collision from the rear to the transport vehicle, In the automatic mode, when a collision is detected by the collision detection sensor while the carrier vehicle is moving forward, the running of the carrier vehicle is prohibited. The carrier vehicle according to claim 1, wherein in the manual mode, even if a collision is detected by the collision detection sensor while the carrier vehicle is moving forward, the running of the carrier vehicle is permitted.

4. The carrier vehicle according to any one of claims 1 to 3, wherein in the automatic mode, it is possible to perform a follow-up operation of moving by tracking a beacon carried by a user and a remote control operation of moving in response to an instruction from a remote control operated by the user.

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