Control device for connected vehicles

Abstract

To provide a control device for a combination vehicle capable of properly coping with abnormality when the abnormality occurs in the combination vehicle.SOLUTION: A control device for a combination vehicle has, as control modes of retreat support control, a normal mode, a bad condition mode, and an abnormality mode. The normal mode is a control mode set when no abnormality of a vehicle state amount is detected. The bad condition mode is a control mode set when the abnormality of the vehicle state amount is detected, and when a substitution value of the vehicle state amount exists. The abnormality mode is a control mode set when the abnormality of the vehicle state amount is detected, and there is no substitution value of the vehicle state amount. The control device continues execution of retreat support control by using the substitution value of the vehicle state amount when the control mode is set to the bad condition mode. The control device executes processing for stopping the combination vehicle when the control mode is set to the abnormality mode.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a control device for articulated vehicles. [Background technology]

[0002] Conventionally, there are articulated vehicles in which a trailer is coupled to a tractor vehicle. Steering an articulated vehicle is more difficult than steering a single vehicle such as a regular passenger car. In particular, when backing up an articulated vehicle, a steering operation opposite to the steering operation required when backing up a single vehicle without a trailer coupled to it is required.

[0003] Therefore, systems have been proposed to assist in the reverse operation of articulated vehicles. For example, the system disclosed in Patent Document 1 automatically steers the vehicle so that the trailer moves along a reference path specified by the driver when the driver controls the reverse speed of the vehicle using the accelerator pedal and brake pedal. The system's curvature controller executes control to reverse the trailer along the reference path based on the steering angle of the tractor. The curvature controller includes a curvature regulator and a hitch angle regulator.

[0004] The curvature regulator calculates a target hitch angle based on the current steering angle provided by the measurement module and the target curvature of the trailer path input through the input device. The hitch angle regulator calculates a steering angle command for the electric power steering system through feedback control of the hitch angle so that the current hitch angle follows the target hitch angle calculated by the curvature regulator. The electric power steering system rotates the steering wheel based on the steering angle command. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] U.S. Patent No. 9,592,851 Summary of the Invention [Problem to be solved by the invention]

[0006] The control device for the articulated vehicles needs to be able to accurately grasp the state of the articulated vehicles in order to appropriately control their behavior. Furthermore, when an abnormality occurs in the articulated vehicles, the control device for the articulated vehicles is required to deal with the abnormality appropriately. [Means for solving the problem]

[0007] A control device for an articulated vehicle that can solve the above problem controls an articulated vehicle having a tractor with steering wheels that change the direction of travel of the vehicle, and a trailer towed by the tractor. The control device for the articulated vehicle is configured to execute backing assist control, which is control for assisting the backing operation of the articulated vehicle, and processing for detecting abnormalities in vehicle state quantities used in the backing assist control. The control device for the articulated vehicle has the following control modes for the backing assist control: The control device has a normal mode that is set when no abnormality in the vehicle state quantity is detected, a malfunction mode that is set when an abnormality in the vehicle state quantity is detected and a substitute value for the vehicle state quantity exists, and an abnormality mode that is set when an abnormality in the vehicle state quantity is detected and a substitute value for the vehicle state quantity does not exist. The control device for the combination vehicles is configured to continue executing the reverse assist control using the substitute value for the vehicle state quantity when the control mode is set to the malfunction mode, and to execute processing to stop the combination vehicles when the control mode is set to the abnormal mode.

[0008] With this configuration, when an abnormality is detected in a vehicle state quantity used for reverse assist control, the behavior of the combination vehicle is controlled depending on whether the control mode of the reverse assist control is malfunction mode or abnormality mode. Therefore, when an abnormality occurs in the state of the combination vehicle, the abnormality can be dealt with appropriately.

[0009] In the above-described control device for combination vehicles, when the control mode is set to the malfunction mode, the control device may be configured to execute processing to stop the combination vehicles when a stop request is made by a specific operation by the operator of the combination vehicles.

[0010] With this configuration, when reverse assist control is being executed in malfunction mode, if the operator's intention to stop the combination vehicle is confirmed, processing is executed to stop the combination vehicle. Because the combination vehicle stops in accordance with the operator's intention to stop, the operator is less likely to feel uncomfortable.

[0011] The control device for combined vehicles described above may be configured to execute an arbitration process for arbitrating the amount of operation by the operator of the combined vehicles and the current control amount when the control mode is set to the malfunction mode.

[0012] With this configuration, the amount of operation by the operator of the combination vehicle and the current amount of control are balanced, making it possible to more appropriately execute reverse assist control in malfunction mode. The control device for combined vehicles described above may be configured so that, when the control mode is set to the malfunction mode, processing is executed to reduce the steering angular velocity of the steered wheels to a value smaller than the steering angular velocity that is allowed when the normal mode is set.

[0013] According to this configuration, when the control mode is set to the malfunction mode, the steering angular velocity of the steered wheels is reduced compared to when the control mode is set to the normal mode, thereby making it possible to more safely execute the reverse assist control in the malfunction mode.

[0014] In the above-described control device for combined vehicles, when the control mode is set to the malfunction mode, and a stop request is made by the operator of the combined vehicles through a specific operation, processing for stopping the combined vehicles may be executed while maintaining a reduced state of the steering angular velocity of the steering wheels.

[0015] With this configuration, the combination vehicle stops in response to the operator's intention to stop, so the operator is less likely to feel uncomfortable. Also, because the steering angular velocity of the steered wheels is reduced compared to when the normal mode is set, reverse assist control can be executed more safely in the malfunction mode.

[0016] In the above-described control device for combined vehicles, when the control mode is set to the abnormal mode, an arbitration process is executed to arbitrate the amount of operation by the operator of the combined vehicles and the current control amount, and then a process is executed to stop the combined vehicles.

[0017] With this configuration, when the control mode is set to the abnormal mode, the amount of operation by the operator of the combination vehicles and the current control amount are negotiated, making it possible to more appropriately execute the process for stopping the combination vehicles.

[0018] The control device for combined vehicles described above may be configured so that, when the control mode is set to the abnormal mode, processing is executed to stop the combined vehicles while maintaining the steering angle of the steered wheels.

[0019] According to this configuration, when the control mode is set to the abnormal mode, the steering angle of the steered wheels is maintained, so that the process for stopping the articulated vehicles can be carried out more safely.

[0020] In the control device for combined vehicles described above, the arbitration process may include a process of selecting, as the braking force to be applied to the wheels, the maximum value between the braking force corresponding to the amount of braking operation by the operator and the current braking force; a process of selecting, as the driving force for driving the combined vehicles, the minimum value between the driving force corresponding to the amount of acceleration operation by the operator and the current driving force; and a process of prioritizing control of the steering angle of the steered wheels in accordance with manual operation by the operator over control of the steering angle of the steered wheels associated with execution of the reverse assist control.

[0021] With this configuration, the braking force is controlled to a larger value, while the driving force is controlled to a smaller value. Furthermore, control of the steering angle according to manual operation by the operator takes priority over control of the steering angle accompanying execution of reverse assist control. Therefore, when the control mode is set to the malfunction mode, reverse assist control can be executed more safely. Furthermore, when the control mode is set to the abnormality mode, processing for stopping the articulated vehicles can be executed more safely.

[0022] In the above-described control device for combined vehicles, when the control mode is set to the malfunction mode or the abnormality mode, the control device may be configured to terminate execution of the reverse assist control when an operation to terminate the reverse assist control by the operator of the combined vehicles is detected after the combined vehicles have come to a stop through execution of processing for stopping the combined vehicles.

[0023] According to this configuration, the execution of the reverse assist control can be terminated based on the operator's intention to terminate the execution of the reverse assist control. In the above-mentioned control device for combined vehicles, when the control mode is set to the malfunction mode or the abnormal mode, if an operation to terminate the reverse assist control by the operator of the combined vehicle is not detected even after a prescribed set time has elapsed, based on the time when the combined vehicle has been stopped through execution of processing to stop the combined vehicle, processing may be configured to execute processing to maintain the combined vehicle in a stopped state.

[0024] With this configuration, when the combination vehicle is stopped through the execution of the process for stopping the combination vehicle, if an operation to end the reverse assist control is not detected within a set time from the point at which the combination vehicle was stopped, a process is executed to maintain the combination vehicle in a stopped state. By restricting the travel of the vehicles, safety is improved.

[0025] The control device for combination vehicles described above may be configured to execute processing for notifying an operator of the combination vehicles of the control mode. This configuration allows the operator to recognize the control mode of the reverse assist control, and also urges the operator to take action according to the control mode.

[0026] In the above-described control device for articulated vehicles, the vehicle state quantities may include a target steering angle of the steered wheels, the steering angle of the steered wheels, the vehicle speed of the articulated vehicles, and a hitch angle which is the angle between a central axis extending in the lengthwise direction of the tractor and a central axis extending in the lengthwise direction of the trailer.

[0027] According to this configuration, abnormalities in a plurality of types of vehicle state quantities used in the reverse assist control can be detected, and therefore, an appropriate response can be made to the abnormalities in each vehicle state quantity. [Effects of the Invention]

[0028] According to the control device for combination vehicles of the present invention, when an abnormality occurs in the combination vehicles, it is possible to appropriately deal with the abnormality. [Brief explanation of the drawings]

[0029] [Figure 1] 1 is a perspective view of an articulated vehicle equipped with an embodiment of a control device for articulated vehicles; [Figure 2] 1 is a block diagram of a backing-up assistance device according to an embodiment; [Figure 3] 3 is a motion model of an articulated vehicle according to one embodiment. [Figure 4] 3 is a motion model of a trailer according to one embodiment. [Figure 5] FIG. 2 is a block diagram of an embodiment of a control device for articulated vehicles. [Figure 6] 4 is a flowchart showing a processing procedure in a malfunction mode and an abnormality mode according to one embodiment of a control device for combined vehicles. DETAILED DESCRIPTION OF THE INVENTION

[0030] A first embodiment of a control device for articulated vehicles will be described below. As shown in FIG. 1, the articulated vehicle 10 has a tractor 11 and a trailer 12. There are various types of tractors 11, but here we will use a pickup truck, a type of small freight vehicle, as an example. The tractor 11 has front wheels 11F and rear wheels 11R. The front wheels 11F include two wheels, a right front wheel and a left front wheel, and the rear wheels 11R include two wheels, a right rear wheel and a left rear wheel. However, FIG. 1 shows only the left front wheel and the left rear wheel. The front wheels 11F and the steering wheel are connected so that power can be transmitted via a steering mechanism (not shown). The front wheels 11F are steered wheels. A steered wheel is a wheel that moves in response to operation of the steering wheel to change the direction of travel of the tractor 11.

[0031] Trailers 12 come in a variety of shapes and sizes depending on their intended use, but a box-shaped trailer will be used here as an example. The trailer 12 has wheels 12R. The wheels 12R include two wheels, a right wheel and a left wheel. However, only the left wheel is shown in FIG. 1.

[0032] The trailer 12 is connected to the rear of the tractor 11 via a ball joint 13. The ball joint 13 has a hitch ball 14 and a hitch coupler 15. The hitch ball 14 is attached to the rear of the tractor 11 via a hitch member. The hitch coupler 15 is attached to the tip of a tongue 16 that protrudes from the front of the trailer 12. By attaching the hitch coupler 15 to the hitch ball 14, the trailer 12 is connected to the tractor 11 so that it can rotate about an axle 17. The axle 17 extends along the height direction of the tractor 11.

[0033] As shown in FIG. 2, the tractor 11 has a display device 20, a steering device 30, and a backing assist device 40. The display device 20 is provided, for example, on an instrument panel inside the vehicle cabin. The display device 20 is, for example, a touch panel, and it is possible to input data and instruct the operation of on-board equipment by touching the display on a screen 21. The screen 21 displays, for example, an assistance start button 21A and an assistance end button 21B. The assistance start button 21A is operated to turn on the reverse assistance function of the combination vehicle 10. The assistance end button 21B is operated to turn off the reverse assistance function of the combination vehicle 10.

[0034] When the assistance start button 21A is operated, the display device 20 generates an assistance start request signal S2. The assistance start request signal S2 is an electrical signal indicating that the operator is requesting the start of execution of reverse assistance control for the combination vehicle 10. When the assistance start button 21A is operated, the display device 20 generates an assistance end request signal S3. The assistance end request signal S3 is an electrical signal indicating that the operator is requesting the end of execution of reverse assistance control for the combination vehicle 10.

[0035] The steering device 30 is, for example, an electric power steering device. The steering device 30 is a system for assisting the operator in steering the steering wheel, and includes a motor 30A, a torque sensor 30B, a steering angle sensor 30C, and a steering control device 30D. The operator includes a driver who drives the combination vehicle 10 from within the cabin of the tractor 11.

[0036] The motor 30A generates an assist force. The assist force is a force for assisting the steering of the steering wheel. The torque of the motor 30A is applied to the steering mechanism of the front wheels 11F via a reduction mechanism. The torque sensor 30B detects the steering torque τ strThe steering angle sensor 30C detects the steering angle α1 of the front wheels 11F, which is the turning angle of the front wheels 11F, based on the rotation angle of the motor 30A, for example. The front wheels 11F and the motor 30A are linked to each other via a steering mechanism. Therefore, there is a correlation between the rotation angle of the motor 30A and the steering angle α1 of the front wheels 11F. Therefore, the steering angle α1 of the front wheels 11F can be obtained based on the rotation angle of the motor 30A.

[0037] The steering control device 30D executes assist control when the reverse assist function of the combination vehicle 10 is turned off. That is, the steering control device 30D executes assist control based on the steering torque τ str By controlling the power supply to the motor 30A based on str The motor 30A generates an assist force corresponding to the torque.

[0038] The steering control device 30D executes steering control of the front wheels 11F when the reverse assist function of the combination vehicle 10 is turned on. That is, when the reverse assist function of the combination vehicle 10 is turned on, the steering control device 30D controls the steering of the front wheels 11F by the target steering angle α1 generated by the reverse assist device 40. * The steering angle α1 of the front wheels 11F is controlled by controlling the rotation angle of the motor 30A based on the target steering angle α1. * is a target value of the steering angle α1 of the front wheels 11F. The steering control device 30D converts the steering angle α1 of the front wheels 11F detected by the steering angle sensor 30C into the target steering angle α1 * In order to make the steering angle α1 coincide with the steering angle α1, the operation of the motor 30A is controlled by executing feedback control of the steering angle α1.

[0039] The reverse assist device 40 assists the reverse operation of the combination vehicle 10 when the reverse assist function of the combination vehicle 10 is turned on. The reverse assist device 40 determines a target steering angle α1 of the front wheels 11F based on the reverse direction or reverse route of the combination vehicle 10 specified by the operator and the steering angle α1 of the front wheels 11F detected by the steering angle sensor 30C. * Calculate the target steering angle α1 *is the target value of the steering angle α1 of the front wheels 11F required for the combination vehicle 10 to move in the reverse direction or along the reverse path specified by the operator. When the reverse assist function of the combination vehicle 10 is turned off, the reverse assist device 40 sets the target steering angle α1 * does not calculate.

[0040] <Reverse support device> Next, the reverse assist device 40 will be described in detail. As shown in FIG. 2, the backing assist device 40 includes an input device 41 and a control device 42.

[0041] The input device 41 has a dial 41A as an operating member. The dial 41A is provided, for example, on a center console inside the vehicle cabin. The dial 41A is operated by the operator when specifying the reverse direction or reverse route of the articulated vehicle 10. The reverse direction or reverse route includes, for example, reverse left turn, reverse right turn, and reverse in a straight line. When making the articulated vehicle 10 make a reverse left turn, the dial 41A is operated counterclockwise based on a reference position corresponding to a straight line route. When making the articulated vehicle 10 make a reverse right turn, the dial 41A is operated clockwise based on the reference position. When making the articulated vehicle 10 reverse in a straight line, the dial 41A is maintained in the reference position. The input device 41 generates an electrical signal S1 that corresponds to the amount or position of operation of the dial 41A based on the reference position.

[0042] The control device 42 has a processing circuit that includes one of the following three components A1, A2, A3. A1. One or more processors that operate according to a computer program, which is software. The processor includes a CPU (central processing unit) and memory.

[0043] A2. One or more dedicated hardware circuits, such as an application specific integrated circuit (ASIC), that perform at least some of the processing. The ASIC includes a CPU and memory.

[0044] A3. A hardware circuit that combines configurations A1 and A2. The memory is a medium that can be read by a computer (here, the CPU), and stores programs that describe processes or instructions for the computer. The memory includes RAM (random access memory) and ROM (read only memory). The CPU executes the programs stored in the memory at set calculation cycles to carry out various types of control. The programs include a program for executing backing assist control for the combination vehicle 10. Backing assist control refers to control for assisting the combination vehicle 10 in reversing operations.

[0045] The control device 42 executes reverse assist control for the combination vehicle 10. The control device 42 starts executing the reverse assist control when the operator operates to start the reverse assist control. The control device 42 stops executing the reverse assist control when the operator operates to end the reverse assist control. The start and end operations of the reverse assist control by the operator are performed via the display device 20. When the assistance start button 21A displayed on the screen 21 of the display device 20 is operated by touch, the control device 42 starts executing the reverse assist control. When the assistance end button 21B displayed on the screen 21 of the display device 20 is operated by touch, the control device 42 ends executing the reverse assist control.

[0046] When reverse assist control is being executed, the control device 42 controls the reverse path of the combination vehicle 10 via the steering device 30 so that the combination vehicle 10 moves in the reverse direction or along the reverse path specified by the operator.

[0047] The control device 42 has a setting unit 42A and a control unit 42B. The setting unit 42A sets the target virtual steering angle α2 of the trailer 12 based on the electrical signal S1 generated by the input device 41, i.e., the operation amount or operation position of the dial 41A relative to the reference position of the dial 41A. * Set the target virtual steering angle α2 *is a target value of the virtual steering angle α2 of the trailer 12. The virtual steering angle α2 refers to the apparent steering angle when the trailer 12 is virtually separated from the tractor 11 and regarded as a single vehicle having virtual front wheels. The setting unit 42A calculates the target virtual steering angle α2 of the trailer 12 by, for example, calculating the operation amount or operation position of the dial 41A. * Using a map that defines the relationship between the target virtual steering angle α2 and the operation amount or operation position of the dial 41A, * The operator operates the dial 41A to calculate the target virtual steering angle α2 according to the desired reverse path along which the trailer 12 is to be reversed. * It is possible to specify

[0048] The control unit 42B controls the target virtual steering angle α2 set by the setting unit 42A. * The hitch angle β detected by the on-board hitch angle sensor 51, the vehicle speed V detected by the on-board vehicle speed sensor 52, and the steering angle α1 detected by the steering angle sensor 30C are input. The hitch angle β is the angle between the central axis extending along the length of the tractor 11 and the central axis extending along the length of the trailer 12. The hitch angle β is also called the bending angle of the trailer 12.

[0049] The control unit 42B controls the target virtual steering angle α2 set by the setting unit 42A. * Based on the hitch angle β, vehicle speed V, and steering angle α1 detected by each sensor, a target steering angle α1 of the front wheels 11F of the tractor 11 is calculated. * The control unit 42B calculates the virtual steering angle α2 of the trailer 12 to be equal to the target virtual steering angle α2 * The target steering angle α1 of the front wheel 11F is set so that it converges to * That is, the control unit 42B calculates the virtual steering angle α2 of the trailer 12 to the target virtual steering angle α2 * In order to make the target steering angle α1 of the front wheels 11F coincide with the target steering angle α1, the feedback control of the virtual steering angle α2 is executed. * The control unit 42B calculates the target steering angle α1 using, for example, nonlinear model predictive control (NMPC). *The following may be calculated.

[0050] <Dynamic model of articulated vehicles> Next, a motion model that represents the behavior of the articulated vehicle 10 moving on a plane will be described. As shown in Figure 3, the motion model of articulated vehicle 10 can be thought of as an equivalent model in which the left and right wheels are moved to the center axis of the vehicle body in a two-dimensional xy coordinate system fixed to the ground. The motion model in Figure 3 is a model of the motion of articulated vehicle 10 when moving forward. However, in order to clarify the behavior of articulated vehicle 10 within the scope of kinematics, the motion model in Figure 3 assumes that no skid occurs in the tires of articulated vehicle 10 at extremely low speeds, and that the vehicle has a velocity vector only in the direction of travel. It also assumes that the road surface is flat and that there are no external disturbances to articulated vehicle 10.

[0051] In the kinematic model of FIG. 3, the parameters of the articulated vehicle 10 used to describe the kinematic relationship between the tractor 11 and the trailer 12 are as follows: C0: Front wheel 11F of tractor 11 B1: Rear wheel 11R of tractor 11 C1: Hitch point of tractor 11 (point indicating the position of hitch ball 14) B2: Trailer 12 wheels V c0 :Velocity vector of front wheel 11F of tractor 11 V B1 : Velocity vector of rear wheel 11R of tractor 11 V c1 :Velocity vector of hitch point C1 of tractor 11 V B2 :Velocity vector of trailer 12 α1: Steering angle of front wheel 11F of tractor 11 α2: Virtual steering angle of trailer 12 γ1: Intermediate variable (velocity vector V between the center axis of the tractor 11 and the hitch point C1) c1 (angle with θ1: Attitude angle of the tractor 11 (angle between the central axis of the tractor 11 and the X axis) θ2: attitude angle of the trailer 12 (angle between the center axis of the trailer 12 and the X axis) β : Hitch angle (the angle between the central axis of the tractor 11 and the central axis of the trailer 12) l1: Wheelbase of tractor 11 h1: distance between rear wheel 11R of tractor 11 and hitch point C1 l2: Virtual wheelbase of trailer 12 However, the signs of each parameter are as follows: The tractor attitude angle θ1 is positive in the counterclockwise direction based on the X-axis. The steering angle α1 of the front wheels 11F of the tractor 11 and the intermediate variable γ1 are positive in the counterclockwise direction based on the central axis of the tractor 11. The hitch angle β is positive in the counterclockwise direction based on the central axis of the tractor 11 or its extension. The vehicle speed V is positive when moving forward and negative when moving backward.

[0052] As shown in FIG. 3, the tractor 11 moves in the direction of the velocity vector V c0 The trailer 12 moves according to the velocity vector V at the hitch point C1, which is the point of connection with the tractor 11. c1 From this, the velocity vector V of the hitch point C1 as seen from the trailer 12 c1 can be regarded as the velocity vector of the virtual front wheels of the trailer 12. In the motion model of FIG. 3, the velocity vector V c1 and the central axis of the trailer 12 is "β-γ1". In this case, as shown in Figure 4, if the trailer 12 is virtually separated from the tractor 11 and viewed as a standalone vehicle with virtual front wheels, the virtual front wheels can be considered to be steered at a virtual steering angle α2 (=-(β-γ1)), which is an apparent steering angle. This shows that the trailer 12 can be considered as a standalone vehicle. Incidentally, in the motion model for backward movement of the articulated vehicle 10, the velocity vector is in the opposite direction to the motion model for forward movement in Figure 3.

[0053] The virtual steering angle α2 of the trailer 12 is expressed by the following equation 1.

[0054]

number

[0055] where "β" is the hitch angle, "l1" is the wheelbase of the tractor 11, "h1" is the distance between the rear wheels 11R of the tractor 11 and the hitch point C1, and "α1" is the steering angle of the front wheels 11F of the tractor 11.

[0056] <Supplementary explanation of the control device 42> Next, the configuration of the control device 42 will be further explained. As shown in FIG. 2, the tractor 11 may be provided with a first yaw rate sensor 53. The first yaw rate sensor 53 detects a yaw rate YR1 of the tractor 11. In addition, the trailer 12 may be provided with a second yaw rate sensor 54. The second yaw rate sensor 54 detects a yaw rate YR2 of the trailer 12. In this case, the control device 42 receives the yaw rate YR1 of the tractor 11 detected via the first yaw rate sensor 53. In addition, the control device 42 receives the yaw rate YR2 of the trailer 12 detected via the second yaw rate sensor 54.

[0057] The tractor 11 may be provided with a wheel speed sensor 55. The wheel speed sensor 55 is provided on the left and right front wheels 11F and rear wheels 11R of the tractor 11. The wheel speed sensor 55 detects a wheel speed V l The wheel speed sensor 55 detects the wheel speed V, which is the rotation speed of the front wheel 11F and the rear wheel 11R on the right side with respect to the traveling direction of the tractor 11. r Detects the wheel speed V l ,V r is used in various in-vehicle systems.

[0058] However, depending on the product specifications, the tractor 11 may be configured without the vehicle speed sensor 52. In this case, the control device 42 detects the wheel speeds V of the left and right front wheels 11F and rear wheels 11R through the wheel speed sensors 55. l ,Vr The vehicle speed V may be calculated using the

[0059] As shown in FIG. 5, the control device 42 includes, in addition to the setting unit 42A and the control unit 42B, an abnormality detection unit 42C, an alternative signal generation unit 42D, and a state manager 42E.

[0060] <Abnormality detection unit 42C> The abnormality detection unit 42C detects abnormalities in the combination vehicle 10. As an example, the abnormality detection unit 42C determines the states of the following four detection targets (B1) to (B4).

[0061] B1. Target steering angle α1 * B2. Steering angle α1 of front wheels 11F B3. Vehicle speed V B4. Hitch angle β <Target steering angle α1 * How to determine the status> Target steering angle α1 * The method for determining the state is as follows: The abnormality detection unit 42C receives the steering angle α1 of the front wheels 11F detected by the steering angle sensor 30C. If the tractor 11 has a first yaw rate sensor 53, the abnormality detection unit 42C receives the yaw rate YR1 of the tractor 11 detected by the first yaw rate sensor 53.

[0062] The abnormality detection unit 42C calculates the first estimated steering angle α of the front wheel 11F using the following formula 2: 11 Calculate ^. "^" indicates an estimated value.

[0063]

number

[0064] where "V" is the vehicle speed. "l" is the wheelbase, and the wheelbase l1 of the tractor 11 is substituted into Equation 2. "A" is the stability factor. The stability factor is an adaptation value that represents the turning characteristics of the vehicle.

[0065] The abnormality detection unit 42C compares the steering angle α1 detected by the steering angle sensor 30C with the first estimated steering angle α 11 ^ and target steering angle α1 * When all of the following three conditions (D1) to (D3) are met, the abnormality detection unit 42C detects that the target steering angle α1 * The abnormality detection unit 42C determines that the value of the target steering angle α1 is abnormal and that an abnormality has occurred for which no alternative value exists. * A detection signal S4 is generated to indicate that an abnormality has occurred in which no substitute value exists.

[0066] D1.│α1-α 11 ^│<α th1 D2.│α1 * -α1│≧α th1 D3.│α1 * -α 11 ^│≧α th1 However, "α th1 " is the first steering angle determination threshold value.

[0067] When all three conditions (D1) to (D3) are met, the steering angle sensor 30C is in a normal state including communication, but for some reason, the target steering angle α1 * It can be said that this is a state in which the value is showing an abnormal value.

[0068] When the condition (D1) is satisfied and the conditions (D2) and (D3) are not satisfied, the abnormality detection unit 42C detects the target steering angle α1 * The abnormality detection unit 42C determines that the value of the target steering angle α1 * The detection signal S4 is generated to indicate that the value of is normal.

[0069] <Method for determining the state of steering angle α1> The method for determining the state of the steering angle α1 is as follows. That is, the abnormality detection unit 42C detects the wheel speeds V of the left and right front wheels 11F and rear wheels 11R detected by the wheel speed sensors 55. l ,Vr Import.

[0070] The abnormality detection unit 42C calculates the estimated yaw rate YR1^ of the tractor 11 using the following equation 3. "^" indicates an estimated value.

[0071]

number

[0072] However, "V l " is the wheel speed of the left wheel relative to the direction of travel of the tractor 11. r " is the wheel speed of the right wheel relative to the direction of travel of the tractor 11. "d" is the distance between the left and right wheels of the tractor 11.

[0073] If the trailer 12 has a wheel speed sensor 55 for each wheel 12R, it is also possible to calculate the estimated yaw rate of the trailer 12 using Equation 3. The abnormality detection unit 42C substitutes the estimated yaw rate YR1^ of the tractor 11 obtained based on the formula 3 into the formula 2, thereby obtaining the second estimated steering angle α of the front wheels 11F. 12 Calculates ^.

[0074] The abnormality detection unit 42C compares the steering angle α1 detected by the steering angle sensor 30C with the first estimated steering angle α 11 ^ and the second estimated steering angle α 12 ^ and are compared with each other. When all of the following three conditions (E1) to (E3) are met, the abnormality detection unit 42C detects three steering angles (α1, α 11 ^,α 12The abnormality detection unit 42C determines that at least two of the three steering angles α1 are abnormal. The abnormality detection unit 42C cannot identify which of the three steering angles is abnormal. Therefore, none of the three steering angles can be used for reverse assist control. The abnormality detection unit 42C determines that an abnormality has occurred in which no substitute value exists for the steering angle α1. The abnormality includes hardware abnormalities in various sensors. The abnormality detection unit 42C generates a detection signal S4 indicating that an abnormality has occurred in which no substitute value exists for the steering angle α1.

[0075] E1.│α1-α 11 ^│≧α th2 E2.│α1-α 12 ^│≧α th2 E3.│α 11 ^-α 12 ^│≧α th2 However, "α th2 " is the second steering angle determination threshold value.

[0076] When the above conditions (E1) and (E2) are satisfied and the condition (E3) is not satisfied, the abnormality detection unit 42C determines that only the first steering angle (α1) is abnormal and the second steering angle (α 11 ^) and the third steering angle (α 12 The abnormality detection unit 42C determines that the steering angle α1 is normal. In other words, it is possible to execute reverse assist control using the second steering angle or the third steering angle instead of the first steering angle. The abnormality detection unit 42C determines that the second steering angle or the third steering angle can be used for reverse assist control of the combination vehicle 10 as a substitute value for the first steering angle. The abnormality detection unit 42C generates a detection signal S4 indicating that an abnormality has occurred in which a substitute value for the steering angle α1 exists.

[0077] When all three conditions (E1) to (E3) are not satisfied, the abnormality detection unit 42C determines that the first to third steering angles are all normal. The abnormality detection unit 42C generates a detection signal S4 indicating that the value of the steering angle α1 is normal.

[0078] <Method for determining the state of vehicle speed V> The method for determining the state of the vehicle speed V is as follows. Here, the control device 42 determines the state of the wheel speed V of each wheel. l ,V r The tractor 11 does not necessarily have to have the vehicle speed sensor 52.

[0079] When all of the following three conditions (F1) to (F3) are met, the abnormality detection unit 42C determines that the value of the vehicle speed V is abnormal and that no alternative value exists. The abnormality detection unit 42C generates a detection signal S4 indicating that an abnormality has occurred in which no alternative value exists for the vehicle speed V.

[0080] F1. The steering angle α1 cannot be detected by the steering angle sensor 30C. F2. The yaw rate YR1 of the tractor 11 cannot be detected by the first yaw rate sensor 53.

[0081] F3. The wheel speed V l ,V r There are two or more wheels that cannot be detected. When the following condition (F4) is satisfied, the abnormality detection unit 42C detects that the wheel speed V l ,V r The wheel speed V of the wheel that can be detected l ,V r The abnormality detection unit 42C determines that it is possible to calculate the vehicle speed V as a substitute value using only the vehicle speed V. The abnormality detection unit 42C generates a detection signal S4 indicating that an abnormality has occurred in which a substitute value for the vehicle speed V exists.

[0082] F4. The wheel speed V l ,V r There are fewer than two wheels that cannot be detected. When none of the four conditions (F1) to (F4) above is satisfied, the abnormality detection unit 42C determines that the vehicle speed V is normal. The abnormality detection unit 42C generates a detection signal S4 indicating that the value of the vehicle speed V is normal.

[0083] <How to determine the hitch angle β> The method for determining the state of the hitch angle β is as follows: That is, when any one of the following four conditions (G1) to (G4) is met, the abnormality detection unit 42C determines that the value of the hitch angle β is abnormal and that no alternative value exists. The abnormality detection unit 42C generates a detection signal S4 indicating that an abnormality has occurred in which no alternative value exists for the hitch angle β.

[0084] G1. The vehicle speed V value is abnormal. G2. The value of steering angle α1 is abnormal. G3. The value of yaw rate YR1 of tractor 11 is abnormal.

[0085] G4. The value of yaw rate YR2 of trailer 12 is abnormal. The abnormality detection unit 42C calculates an estimated hitch angle β^. The estimated hitch angle β^ is an estimated value of the hitch angle β calculated based on vehicle state quantities. "^" indicates an estimated value. The vehicle state quantities include the vehicle speed V and the steering angle α1 of the front wheels 11F. If the combination vehicle 10 is provided with a first yaw rate sensor 53 and a second yaw rate sensor 54, the vehicle state quantities include the yaw rate YR1 of the tractor 11 and the yaw rate YR2 of the trailer 12.

[0086] The abnormality detection unit 42C calculates the estimated hitch angle β^ using a formula obtained by integrating the following formula 4.

[0087]

number

[0088] Here, "l1" is the wheelbase of the tractor 11. 2」 is the virtual wheelbase of the trailer 12. B1 " is the velocity vector of the rear wheel 11R of the tractor 11. "h1" is the distance between the rear wheel 11R of the tractor 11 and the hitch point C1. "α1" is the steering angle of the front wheel 11F of the tractor 11.

[0089] If the combination vehicle 10 has a first yaw rate sensor 53 and a second yaw rate sensor 54, the abnormality detection section 42C may use the following equation 3 to calculate the estimated hitch angle β^.

[0090]

number

[0091] Here, "l1" is the wheelbase of the tractor 11. 2」 is the virtual wheelbase of the trailer 12. B1 " is the velocity vector of the rear wheels 11R of the tractor 11. "h1" is the distance between the rear wheels 11R of the tractor 11 and the hitch point C1. "α1" is the steering angle of the front wheels 11F of the tractor 11. "β(·)" is the time rate of change of the hitch angle β, i.e., the hitch angular velocity. "·" indicates time differentiation. The hitch angular velocity (·) in Equation 5 is substituted with the value of the difference between the yaw rate YR1 of the tractor 11 detected by the first yaw rate sensor 53 and the yaw rate YR2 of the trailer 12 detected by the second yaw rate sensor 54.

[0092] When the following condition (G5) or condition (G6) is met, the abnormality detection unit 42C determines that the estimated hitch angle β^ can be used as a substitute value for the hitch angle β detected by the hitch angle sensor 51. The abnormality detection unit 42C generates a detection signal S4 indicating that an abnormality has occurred in which a substitute value for the hitch angle β exists.

[0093] G5.│β^-β│≧β th G6. The hitch angle β cannot be detected through the hitch angle sensor 51. However, "β th " is the hitch angle determination threshold.

[0094] When neither of the two conditions (G5) nor (G6) is satisfied, the abnormality detection unit 42C determines that the value of the hitch angle β detected by the hitch angle sensor 51 is normal. The abnormality detection unit 42C generates a detection signal S4 indicating that the value of the hitch angle β is normal.

[0095] <Alternative signal generation unit 42D> The substitute signal generating unit 42D generates substitute signals for the detection targets (B1) to (B4) when the detection signal S4 generated by the abnormality detecting unit 42C indicates that an abnormality for which a substitute value exists has occurred in at least one of the four detection targets (B1) to (B4). Specifically, it does so as follows.

[0096] The substitute signal generator 42D generates a first substitute signal S5 when the detection signal S4 indicates that an abnormality for which a substitute value exists has occurred in the detection target (B2), i.e., the steering angle α1 detected through the steering angle sensor 30C. The first substitute signal S5 is a first estimated steering angle α1 calculated based on the yaw rate YR1 of the tractor 11. 11 The alternative signal generating unit 42D, like the abnormality detecting unit 42C, generates an electric signal indicating the first estimated steering angle α of the front wheels 11F. 11 Calculates ^.

[0097] The alternative signal generating unit 42D detects whether the detection signal S4 is a signal corresponding to the detection object (B3), i.e., the wheel speed V l ,V r When the vehicle speed V calculated based on the wheel speed V indicates that an abnormality for which a substitute value exists has occurred, the second substitute signal S6 is generated. l ,V r The wheel speed V of the wheel that can be detected l ,V r It is an electrical signal indicating the vehicle speed V calculated using only the

[0098] The substitute signal generating unit 42D generates a third substitute signal S7 when the detection signal S4 indicates that an abnormality for which an alternative value exists has occurred in the detection object (B4), i.e., the hitch angle β detected by the hitch angle sensor 51. The third substitute signal S7 is an electrical signal that indicates the estimated hitch angle β^. The substitute signal generating unit 42D calculates the estimated hitch angle β^ in the same manner as the abnormality detecting unit 42C.

[0099] When the detection signal S4 generated by the abnormality detection unit 42C indicates that an abnormality for which no alternative value exists has occurred in at least one of the four detection targets (B1) to (B4), the alternative signal generation unit 42D does not generate an alternative signal for those detection targets (B1) to (B4).

[0100] When the detection signal S4 generated by the abnormality detection unit 42C indicates that all of the four detection targets (B1) to (B4) are normal, the substitute signal generation unit 42D does not generate substitute signals for those detection targets (B1) to (B4).

[0101] <State Manager 42E> Based on the detection signal S4 generated by the abnormality detection unit 42C, the state manager 42E determines the control mode of the reverse assist control for the combination vehicle 10. The state manager 42E sets the control mode of the reverse assist control to one of the following three control modes (C1) to (C3).

[0102] C1.Normal mode C2. Bad mood C3. Abnormal mode When the detection signal S4 generated by the abnormality detection unit 42C indicates that all of the four detection targets (B1) to (B4) are normal, the state manager 42E sets the control mode of the reverse assist control to the normal mode.

[0103] When the detection signal S4 generated by the abnormality detection unit 42C indicates that an abnormality for which an alternative value exists has occurred in at least one of the four detection targets (B1) to (B4), the state manager 42E sets the control mode of the reverse assist control to a malfunction mode.

[0104] When the detection signal S4 generated by the abnormality detection unit 42C indicates that an abnormality for which no alternative value exists has occurred in at least one of the four detection targets (B1) to (B4), the state manager 42E sets the control mode of the reverse assist control to abnormality mode.

[0105] The state manager 42E generates an electrical signal S10 indicating the control mode to be set. The display device 20 recognizes the control mode of the reversing assist control based on the electrical signal S10. The display device 20 displays the recognized control mode on the screen 21. The operator of the tractor 11 can visually recognize the control mode. The control unit 42B recognizes the control mode of the reversing assist control based on the electrical signal S10. The control unit 42B executes the reversing assist control in accordance with the recognized control mode.

[0106] The state manager 42E generates a first request signal S8 to the drive device 60 of the tractor 11 and a second request signal S9 to the brake device 70 of the tractor 11 according to the control mode of the reverse assist control. The state manager 42E generates the first request signal S8 and the second request signal S9 when the control mode is the malfunction mode and the abnormality mode.

[0107] The drive unit 60 includes a drive source for propelling the tractor 11 and an automatic transmission. The drive source generates drive force for propelling the tractor 11 in accordance with the amount of depression of the accelerator pedal. The drive source is, for example, an internal combustion engine such as an engine, or a traction motor. The automatic transmission has a parking lock mechanism. The parking lock mechanism is a mechanism that locks the rotation of the wheels of the tractor 11, for example the front wheels, inside the automatic transmission to prevent them from rotating when the shift range of the tractor 11 is switched to the parking range.

[0108] The first request signal S8 includes an electrical signal requesting the drive source to generate a drive force according to the control mode and an electrical signal requesting the parking lock mechanism to switch from an unlocked state to a locked state. The first request signal S8 also includes an electrical signal indicating a target value of the drive force to be generated by the drive source. The target value of the drive force is set in advance according to the control mode. The drive force is a controlled variable.

[0109] The braking device 70 generates a braking force to slow down or stop the tractor 11 according to the amount of depression of the brake pedal. The braking device 70 includes an electric parking brake (EPB). The electric parking brake is used to fix the wheels when parking or stopping. The electric parking brake is activated by driving a built-in motor.

[0110] The second request signal S9 includes an electrical signal for requesting the braking device 70 to generate a braking force according to the control mode, and an electrical signal for requesting the braking device 70 to operate the electric parking brake. The second request signal S9 also includes an electrical signal indicating a target value of the braking force to be generated by the braking device 70. The target value of the braking force is set in advance according to the control mode. The braking force is a controlled variable.

[0111] <Processing procedure of the control device 42> Next, the processing procedure executed by the control device 42 will be described with reference to the flowchart of Fig. 6. The processing according to the flowchart is initiated when the operator performs an operation to start reverse assist control, i.e., when the operator touches the assist start button 21A displayed on the screen 21 of the display device 20. The processing according to the flowchart is executed at a predetermined control cycle.

[0112] As shown in the flowchart of FIG. 6, the control device 42 first determines the control mode of the reverse assist control (step S101). When all of the four detection targets (B1) to (B4) are normal, the control device 42 determines that the control mode of the reversing assist control is the normal mode. When an abnormality for which a substitute value exists occurs in at least one of the four detection targets (B1) to (B4), the control device 42 determines that the control mode of the reversing assist control is the malfunction mode. When an abnormality for which a substitute value does not exist occurs in at least one of the four detection targets (B1) to (B4), the control device 42 determines that the control mode of the reversing assist control is the malfunction mode. When the control device 42 determines that the control mode is the normal mode, it ends the processing. When the control device 42 determines that the control mode is the malfunction mode, it proceeds to step S102.

[0113] In step S102, the control device 42 determines whether it is necessary to shift the control mode from the malfunction mode to the abnormality mode. The processing content of step S102 is the same as the processing executed in the previous step S101. When it is determined that it is necessary to shift the control mode to the abnormality mode (YES in step S102), the control device 42 shifts the control mode to the abnormality mode. Specifically, the control device 42 shifts the processing to step S112, which will be described later. When it is determined that it is not necessary to shift the control mode to the abnormality mode (NO in step S102), the control device 42 shifts the processing to step S103.

[0114] In step S103, the control device 42 executes arbitration processing. The arbitration processing is processing for arbitrating the operation amount by the operator and the current control amount. The arbitration processing is performed based on the viewpoint of ensuring higher safety according to the control mode.

[0115] The control device 42 detects the depression amount of the accelerator pedal, which is an operation amount. The depression amount of the accelerator pedal is the acceleration operation amount by the operator. The control device 42 calculates the driving force generated by the drive device 60 based on the depression amount of the accelerator pedal. The driving force is an acceleration control amount. The control device 42 compares a first driving force corresponding to the depression amount of the accelerator pedal with a second driving force, which is the current driving force. The control device 42 selects the minimum value of the first driving force and the second driving force. The control device 42 generates a first request signal S8 including the driving force selected as the target value of the driving force.

[0116] The control device 42 detects the amount of depression of the brake pedal. The amount of depression of the brake pedal is the amount of braking operation by the operator. The control device 42 calculates the braking force to be generated by the braking device 70 based on the amount of depression of the brake pedal. The braking force is the braking control amount. The control device 42 compares a first braking force corresponding to the amount of depression of the brake pedal with a second braking force, which is the current braking force. The control device 42 selects the maximum value of the first braking force and the second braking force. The control device 42 generates a second request signal S9 including the braking force selected as the target value of the braking force.

[0117] The control device 42 prioritizes the control of the steering angle α1 of the front wheels 11F according to the manual operation of the operator over the control of the steering angle α1 of the front wheels 11F according to the execution of the reverse assist control. * In this case, the steering angle α1 is not based on the steering angle α1 in accordance with the steering state of the steering wheel of the operator, but on the steering angle α1 in accordance with the steering state of the steering wheel of the operator.

[0118] Next, the control device 42 executes a process for reducing the steering angular velocity of the front wheels 11F (step S104). The steering angular velocity is the time change rate of the steering angle α1. The control device 42 executes a process for reducing the steering angular velocity to a value smaller than the steering angular velocity allowed when the normal mode is set. The control device 42 executes a process for reducing the steering angular velocity to a value smaller than the target steering angle α1 of the front wheels 11F, for example, so that the steering angular velocity is reduced to a value less than the set limit value. * The limit value is set, for example, through simulation using a vehicle model, from the viewpoint of improving safety. The limit value is a value smaller than the steering angular velocity that is allowed when the control mode is the normal mode.

[0119] Next, the control device 42 determines whether or not there is a stop request (step S105). A stop request is, for example, the operator depressing the brake pedal. The brake pedal operation is detected, for example, by an on-board pedal stroke sensor. The pedal stroke sensor generates an electric signal S11 corresponding to the amount of brake pedal operation. The control device 42 recognizes whether or not the brake pedal has been operated based on the electric signal S11. When the control device 42 recognizes that the brake pedal has not been operated, it determines that there is no stop request from the operator (NO in step S105) and proceeds to step S102. When the control device 42 recognizes that the brake pedal has been operated, it determines that there is a stop request from the operator (YES in step S105) and proceeds to step S106.

[0120] In step S106, the control device 42 carries out processing to stop the combination vehicle 10 while maintaining the steering angular velocity reduced to a value less than the limit value. The processing to stop the combination vehicle 10 is processing to operate the braking device 70.

[0121] When the control device 42 confirms that the combination vehicle 10 has stopped (step S107), the control device 42 proceeds to the process of step S108. The control device 42 determines, based on the vehicle speed V, for example, whether the combination vehicle 10 has stopped.

[0122] In step S108, the control device 42 determines whether an operation to end the reverse assist control has been performed. When the control device 42 recognizes that the assist end button 21B displayed on the screen 21 of the display device 20 has been touched, the control device 42 determines that an operation to end the reverse assist control has been performed. When the control device 42 does not recognize that the assist end button 21B displayed on the screen 21 of the display device 20 has been touched, the control device 42 determines that an operation to end the reverse assist control has been performed.

[0123] When it is determined that an operation to terminate the reverse assist control has been performed (YES in step S108), the control device 42 terminates the execution of the reverse assist control (step S109) and ends the process. When it is not determined that an operation to terminate the reverse assist control has been performed (NO in step S108), the control device 42 determines whether a set time has elapsed (step S110). The criterion for determining whether the set time has elapsed is the time when it was confirmed in the previous step S107 that the vehicle was stopped.

[0124] When it is determined that the set time has elapsed since the combination vehicle 10 came to a stop, the control device 42 executes processing to maintain the combination vehicle 10 in a stopped state (step S111) and ends the processing. The control device 42 executes processing to activate the electric parking brake and processing to switch the parking lock mechanism from an unlocked state to a locked state.

[0125] In addition, when the control device 42 determines in the previous step S101 that the control mode is the abnormal mode, the control device 42 proceeds to the arbitration process of step S112 and then to step S113. The process content of step S112 is the same as the process executed in the previous step S103.

[0126] In step S113, the control device 42 operates the braking device 70 while maintaining the steering angle α1 of the front wheels 11F, and then proceeds to step S107. <Effects of the embodiment> This embodiment has the following advantages.

[0127] (1) The control device 42 has a normal mode, a malfunction mode, and an abnormality mode as control modes for reverse assist control. The normal mode is a control mode that is set when no abnormality in the vehicle state quantity is detected. The vehicle state quantity includes the four detection targets (B1) to (B4) mentioned above. The malfunction mode is a control mode that is set when an abnormality in the vehicle state quantity is detected and an alternative value for the vehicle state quantity exists. The abnormality mode is a control mode that is set when an abnormality in the vehicle state quantity is detected and an alternative value for the vehicle state quantity does not exist.

[0128] When the control mode is set to malfunction mode, the control device 42 continues to execute reverse assist control using alternative values ​​of the vehicle state quantities. Furthermore, when the control mode is set to abnormality mode, the control device 42 executes processing to stop the combination vehicle 10. In this way, when an abnormality in a vehicle state quantity used for reverse assist control is detected, the behavior of the combination vehicle 10 is controlled depending on whether the control mode of the reverse assist control is malfunction mode or abnormality mode. Therefore, it is possible to appropriately deal with the abnormality in the vehicle state quantity.

[0129] (2) When the control mode is set to malfunction mode, the control device 42 executes processing to stop the combination vehicle 10 when a stop request is made through a specific operation by the operator of the combination vehicle 10. In other words, when reverse assist control is being executed in malfunction mode, processing to stop the combination vehicle 10 is executed when the operator's intention to stop the combination vehicle 10 is confirmed. For this reason, the combination vehicle 10 stops in accordance with the operator's intention to stop, so the operator is less likely to feel uncomfortable.

[0130] (3) When the control mode is set to malfunction mode, the control device 42 executes arbitration processing to arbitrate the amount of operation by the operator of the combination vehicle 10 and the current control amount. By arbitrating the amount of operation by the operator of the combination vehicle 10 and the current control amount, reverse assist control in malfunction mode can be executed more appropriately.

[0131] (4) When the control mode is set to the malfunction mode, the control device 42 executes processing to reduce the steering angular velocity of the front wheels 11F to a value smaller than the steering angular velocity allowed when the normal mode is set. Therefore, when the control mode is set to the malfunction mode, the steering angular velocity of the front wheels 11F is reduced compared to when the normal mode is set, thereby enabling the reverse assist control in the malfunction mode to be executed more safely.

[0132] (5) When the control mode is set to malfunction mode, and a stop request is made by the operator of the combined vehicle 10 through a specific operation, the control device 42 executes processing to stop the combined vehicle 10 while maintaining a reduced steering angular velocity of the front wheels 11F. Because the combined vehicle 10 stops in response to the operator's intention to stop, the operator is less likely to feel uncomfortable. Furthermore, because the steering angular velocity of the front wheels 11F is reduced compared to when the normal mode is set, reverse assist control in malfunction mode can be executed more safely.

[0133] (6) When the control mode is set to the abnormal mode, the control device 42 executes arbitration processing to reconcile the amount of operation by the operator of the combination vehicle 10 with the current control amount, and then executes processing to stop the combination vehicle 10. When the control mode is set to the abnormal mode, arbitration is performed between the amount of operation by the operator of the combination vehicle 10 and the current control amount, making it possible to more appropriately execute processing to stop the combination vehicle.

[0134] (7) When the control mode is set to the abnormal mode, the control device 42 executes processing to stop the combination vehicle 10 while maintaining the steering angle α1 of the front wheels 11F. By maintaining the steering angle α1 of the front wheels 11F when the control mode is set to the abnormal mode, processing to stop the combination vehicle 10 can be executed more safely.

[0135] (8) The arbitration process includes processing for selecting the maximum value between the current braking force and the braking force corresponding to the amount of braking operation by the operator as the braking force to be applied to the wheels of the combination vehicle 10. The arbitration process also includes processing for selecting the minimum value between the current driving force and the driving force corresponding to the amount of acceleration operation by the operator as the driving force for traveling the combination vehicle 10. The arbitration process also includes processing for prioritizing control of the steering angle α1 of the front wheels 11F in accordance with manual operation by the operator over control of the steering angle α1 of the front wheels 11F associated with execution of reverse assist control.

[0136] With this configuration, the braking force is controlled to a larger value, while the driving force is controlled to a smaller value. Also, control of the steering angle α1 according to manual operation by the operator takes priority over control of the steering angle α1 accompanying execution of reverse assist control. Therefore, when the control mode is set to the malfunction mode, reverse assist control can be executed more safely. Also, when the control mode is set to the abnormality mode, processing for stopping the articulated vehicles can be executed more safely.

[0137] (9) When the control mode is set to malfunction mode or abnormality mode, the control device 42 terminates the execution of reverse assist control when it detects an operation by the operator of the combination vehicle 10 to terminate the reverse assist control after the combination vehicle 10 has come to a stop through the execution of processing to stop the combination vehicle 10. With this configuration, it is possible to terminate the execution of reverse assist control based on the operator's intention to terminate the execution of the reverse assist control.

[0138] (10) When the control mode is set to malfunction mode or abnormality mode, the control device 42 executes the following process when the combination vehicle 10 has been stopped through the execution of the process for stopping the combination vehicle 10. In other words, when the control device 42 does not detect an operation to terminate reverse assist control by the operator of the combination vehicle 10 after a set period of time has elapsed from the time the combination vehicle came to a stop, it executes process to maintain the combination vehicle 10 in a stopped state. Therefore, safety is improved by restricting the driving of the vehicle.

[0139] (11) The control device 42 executes processing to notify the operator of the combination vehicle 10 of the control mode. The control device 42 notifies the operator of the control mode visually, for example, via the display device 20. This allows the operator to recognize the control mode of the reverse assist control. Furthermore, the operator can be prompted to take action according to the control mode.

[0140] (12) The control device 42 determines the target steering angle α1 of the front wheels 11F. * , the steering angle α1 of the front wheels 11F, the vehicle speed V, and the hitch angle β are detected. The targets for detecting these abnormalities are all multiple types of vehicle state quantities used for reverse assist control. Therefore, it is possible to appropriately deal with abnormalities in multiple types of vehicle state quantities.

[0141] (13) In the same way as specifying the steering angle of the front wheels 11F by steering the steering wheel in a normal passenger car, the operator can specify the target virtual steering angle α2 of the trailer 12 by operating the input device 41. * The operator can specify the target virtual steering angle α2 of the trailer 12 through the operation of the input device 41. * By specifying this, the reverse motion of the nonlinear and unstable trailer 12 can be controlled as if it were a single vehicle consisting of only the tractor 11, i.e., a standard passenger car with front wheel steering. This makes it possible to more appropriately assist the reverse operation of the articulated vehicle 10. The operator can reverse the articulated vehicle 10 with the same feeling as if it were a standard passenger car.

[0142] <Other embodiments> This embodiment may be modified as follows. 6, the control device 42 may execute a process for decreasing the vehicle speed V in addition to the process for decreasing the steering angular velocity. Also, in step S104, the control device 42 may execute a process for decreasing the vehicle speed V instead of the process for decreasing the steering angular velocity.

[0143] 6, the processes of steps S102 to 104 may be omitted. The processes of steps S102 to 104 may be executed in appropriate combination depending on product specifications, etc. When the process of step S106 is omitted, the process of maintaining the state in which the steering angular velocity is reduced may not be executed in the process of step S106.

[0144] 6, the process of step S112 may be omitted. In this case, when the control device 42 determines in step S101 that the control mode is the abnormal mode, the process proceeds to step S113. Also, in the process of step S113, the process of maintaining the steering angle α1 of the front wheels 11F may not be executed.

[0145] The anomaly detection unit 42C and the state manager 42E may be integrated into a single processing unit. This single processing unit has the functions of the anomaly detection unit 42C and the functions of the state manager. For example, the anomaly detection unit 42C may also have the functions of the state manager 42E. In this case, the state manager 42E may be omitted. Alternatively, the state manager 42E may also have the functions of the anomaly detection unit 42C. In this case, the anomaly detection unit 42C may be omitted. [Explanation of symbols]

[0146] 10...Articulated vehicle 11...Tractor 11F...Front wheels (steering wheels) 12...Trailer 42...Control device

Claims

1. The control target is a combination vehicle having a tractor with steering wheels that change the direction of travel of the vehicle and a trailer towed by the tractor, A control device for combination vehicles configured to execute a reverse assist control that is a control for assisting a reverse operation of the combination vehicles, and a process for detecting an abnormality in a vehicle state quantity used in the reverse assist control, As a control mode of the reverse assist control, a normal mode that is set when no abnormality is detected in the vehicle state quantity; a malfunction mode that is set when an abnormality in the vehicle state quantity is detected and an alternative value for the vehicle state quantity exists; an abnormality mode that is set when an abnormality in the vehicle state quantity is detected and there is no alternative value for the vehicle state quantity, When the control mode is set to the malfunction mode, the execution of the reverse assist control is continued using the substitute value of the vehicle state quantity; when the control mode is set to the abnormal mode, a process for stopping the combination of vehicles is executed, When the control mode is set to the malfunction mode, a control device for combination vehicles configured to execute an arbitration process for arbitrating an operation amount by an operator of the combination vehicles and a current control amount;

2. The control target is a combination vehicle having a tractor with steering wheels that change the direction of travel of the vehicle and a trailer towed by the tractor, A control device for combination vehicles configured to execute a reverse assist control that is a control for assisting a reverse operation of the combination vehicles, and a process for detecting an abnormality in a vehicle state quantity used in the reverse assist control, As a control mode of the reverse assist control, a normal mode that is set when no abnormality is detected in the vehicle state quantity; a malfunction mode that is set when an abnormality in the vehicle state quantity is detected and an alternative value for the vehicle state quantity exists; an abnormality mode that is set when an abnormality in the vehicle state quantity is detected and there is no alternative value for the vehicle state quantity, When the control mode is set to the malfunction mode, the execution of the reverse assist control is continued using the substitute value of the vehicle state quantity; when the control mode is set to the abnormal mode, a process for stopping the combination of vehicles is executed, a control device for articulated vehicles configured to, when the control mode is set to the malfunction mode, execute processing to reduce the steering angular velocity of the steered wheels to a value smaller than the steering angular velocity allowed when the normal mode is set.

3. The control target is a combination vehicle having a tractor with steering wheels that change the direction of travel of the vehicle and a trailer towed by the tractor, A control device for combination vehicles configured to execute a reverse assist control that is a control for assisting a reverse operation of the combination vehicles, and a process for detecting an abnormality in a vehicle state quantity used in the reverse assist control, As a control mode of the reverse assist control, a normal mode that is set when no abnormality is detected in the vehicle state quantity; a malfunction mode that is set when an abnormality in the vehicle state quantity is detected and an alternative value for the vehicle state quantity exists; an abnormality mode that is set when an abnormality in the vehicle state quantity is detected and there is no alternative value for the vehicle state quantity, When the control mode is set to the malfunction mode, the execution of the reverse assist control is continued using the substitute value of the vehicle state quantity; when the control mode is set to the abnormal mode, a process for stopping the combination of vehicles is executed, a control device for combination vehicles that, when the control mode is set to the abnormal mode, executes arbitration processing to arbitrate the amount of operation by the operator of the combination vehicles and the current control amount, and then executes processing to stop the combination vehicles.

4. The control target is a combination vehicle having a tractor with steering wheels that change the direction of travel of the vehicle and a trailer towed by the tractor, A control device for combination vehicles configured to execute a reverse assist control that is a control for assisting a reverse operation of the combination vehicles, and a process for detecting an abnormality in a vehicle state quantity used in the reverse assist control, As a control mode of the reverse assist control, a normal mode that is set when no abnormality is detected in the vehicle state quantity; a malfunction mode that is set when an abnormality in the vehicle state quantity is detected and an alternative value for the vehicle state quantity exists; an abnormality mode that is set when an abnormality in the vehicle state quantity is detected and there is no alternative value for the vehicle state quantity, When the control mode is set to the malfunction mode, the execution of the reverse assist control is continued using the substitute value of the vehicle state quantity; when the control mode is set to the abnormal mode, a process for stopping the combination of vehicles is executed, a control device for articulated vehicles, wherein the vehicle state quantities include a target steering angle of the steered wheels, the steering angle of the steered wheels, the vehicle speed of the articulated vehicles, and a hitch angle which is the angle between a central axis extending in the length direction of the tractor and a central axis extending in the length direction of the trailer.

5. A control device for a combination vehicle as described in any one of claims 1 to 4, configured to, when the control mode is set to the malfunction mode, execute processing to stop the combination vehicle when a stop request is made through a specific operation by the operator of the combination vehicle.

6. A control device for a combination vehicle as described in claim 2, which is configured, when the control mode is set to the malfunction mode, to execute processing to stop the combination vehicle while maintaining a reduced state of the steering angular velocity of the steering wheels when a stop request is made through a specific operation by the operator of the combination vehicle.

7. 4. The control device for an articulated vehicle according to claim 3, wherein when the control mode is set to the abnormal mode, a process is executed to stop the articulated vehicle while maintaining the steering angle of the steered wheels.

8. The arbitration process includes: a process of selecting, as the braking force to be applied to the wheels, a maximum value between a braking force corresponding to the amount of braking operation by the operator and a current braking force; a process of selecting, as a driving force for driving the combination vehicle, a minimum value between a driving force corresponding to an amount of acceleration operation by the operator and a current driving force; and processing for prioritizing control of the steering angle of the steered wheels in accordance with manual operation by the operator over control of the steering angle of the steered wheels in conjunction with execution of the reverse assist control.

9. 6. The control device for combined vehicles according to claim 5, wherein, when the control mode is set to the malfunction mode or the abnormality mode, the control device is configured to terminate the execution of the reversing assist control when an operation to terminate the reversing assist control by an operator of the combined vehicles is detected after the combined vehicles have come to a stop through execution of processing for stopping the combined vehicles.

10. 6. A control device for an articulated vehicle according to claim 5, wherein when the control mode is set to the malfunction mode or the abnormality mode, if an operation to terminate the reverse assist control by the operator of the articulated vehicle is not detected even after a predetermined set time has elapsed, based on the time point at which the articulated vehicle comes to a stop through execution of processing to stop the articulated vehicle, processing is executed to maintain the articulated vehicle in a stopped state.

11. 5. The control device for combination vehicles according to claim 1, wherein the control device is configured to execute a process for notifying an operator of the combination vehicles of the control mode.

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