Control device for connected vehicles

Abstract

To provide a controller for a combination vehicle capable of achieving a more appropriate vehicle behavior.SOLUTION: A combination vehicle includes: a tractor having steering wheels which are wheels for changing a traveling direction of a vehicle; and a trailer towed by the tractor. A controller for the combination vehicle supports a backward operation of the trailer by making controlled variables follow a target value of backward control set through a particular operation by an operator when a backward operation of the combination vehicle is executed. The controller for the combination vehicle is configured to execute processing for restricting the target value and processing for restricting a time change rate of the target value according to a point of view of suppressing the generation of a jackknife phenomenon. The target value is, for example, a target virtual steering angle α2* or a target hitch angle β*.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 reversing an articulated vehicle, a steering operation opposite to the steering operation required when reversing a single vehicle without a trailer coupled to it is required. Furthermore, when reversing an articulated vehicle, it is necessary to apply the brakes, for example, to stabilize the combination of the vehicle and trailer before a so-called jackknife phenomenon occurs. Jackknife refers to a phenomenon in which the connection between the vehicle and trailer bends significantly when the articulated vehicle is reversed.

[0003] Therefore, for example, the reversing assist system of Patent Document 1 limits the hitch angle. The hitch angle is the angle between the central axis extending in the longitudinal direction of the vehicle and the central axis extending in the longitudinal direction of the trailer. The reversing assist system calculates a first hitch limit angle based on the desired curvature of the trailer selected by operating a knob. However, the vehicle user can set a second hitch limit angle within the first hitch limit angle. The vehicle user can select either the first limit angle or the second limit angle. The reversing assist system displays the first limit angle or the second limit angle selected by the vehicle user on a display device. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] US Patent Application Publication No. 2020 / 0164919 Summary of the Invention [Problem to be solved by the invention]

[0005] In a reversing assistance system that limits the hitch angle, as in Patent Document 1, the following concerns exist: A response delay occurs in the hitch angle due to physical constraints of the articulated vehicles. For this reason, for example, when the trailer curvature set by operating a knob changes suddenly, the hitch angle may not respond appropriately to the sudden change in trailer curvature. This may result in the occurrence of jackknife. A control device for articulated vehicles is required to more appropriately suppress the occurrence of jackknife, and ultimately to achieve more appropriate vehicle behavior. [Means for solving the problem]

[0006] The articulated vehicle control device that solves the above-mentioned problem controls an articulated vehicle that includes a tractor with steering wheels that change the vehicle's direction of travel, and a trailer towed by the tractor. When the articulated vehicle is reversed, the articulated vehicle control device assists the trailer in reversing by making the control variable follow a target value for reverse control that is set through a specific operation by the operator. The articulated vehicle control device is configured to execute processing to limit the target value and processing to limit the time rate of change of the target value, based on the perspective of achieving appropriate vehicle behavior.

[0007] According to this configuration, the target value of the reverse control is limited from the viewpoint of realizing appropriate vehicle behavior, thereby making it possible to realize appropriate vehicle behavior. Also, from the viewpoint of realizing appropriate vehicle behavior, the time change rate of the target value is limited, thereby suppressing the occurrence of so-called overshoot, in which the controlled variable exceeds the target value. This makes it possible to realize appropriate vehicle behavior.

[0008] The control device for articulated vehicles described above may be configured to execute a process for limiting the target value and a process for limiting a time rate of change of the target value, from the viewpoint of suppressing the occurrence of a jackknife phenomenon.

[0009] According to this configuration, the target value of the reverse control is limited from the viewpoint of suppressing the occurrence of the jackknife, thereby suppressing the occurrence of the jackknife. Also, the time rate of change of the target value is limited from the viewpoint of suppressing the occurrence of the jackknife, thereby suppressing the occurrence of so-called overshoot, in which the controlled variable exceeds the target value. This makes it possible to more appropriately suppress the occurrence of the jackknife. Ultimately, it is possible to achieve more appropriate vehicle behavior.

[0010] In the above control device for articulated vehicles, the target value may be a target hitch angle, which is a target value for the hitch angle, which is the angle between a central axis extending in the longitudinal direction of the tractor and a central axis extending in the longitudinal direction of the trailer. In this case, the control device for articulated vehicles may be configured to calculate a limit value for the time rate of change of the target hitch angle by substituting a maximum steering angle, which is the maximum value of the physically possible steering angle of the steered wheels, or a maximum steering angular velocity, which is obtained by differentiating the maximum steering angle, into an equation of motion for a hitch angular velocity, which is the time rate of change of the hitch angle.

[0011] With this configuration, the time rate of change of the target hitch angle is limited, thereby preventing the hitch angle from exceeding the target hitch angle, or what is known as overshooting. This makes it possible to more appropriately prevent the occurrence of jackknife motion, thereby achieving more appropriate vehicle behavior.

[0012] The control device for the above-described articulated vehicles may be configured to execute a process of calculating a jackknife hitch angle, which is a boundary value of the hitch angle that determines whether or not a jackknife phenomenon will occur, by substituting zero as the value of the hitch angular velocity and the value of the maximum steering angle into an equation of motion for the hitch angular velocity and solving for the hitch angle, and a process of setting the jackknife hitch angle as a limit value for the target hitch angle.

[0013] This configuration limits the hitch angle to the jackknife hitch angle. Since the hitch angle is prevented from exceeding the jackknife hitch angle, the occurrence of the jackknife phenomenon can be more appropriately prevented. Consequently, more appropriate vehicle behavior can be achieved.

[0014] In the above control device for articulated vehicles, the target value may be a target virtual steering angle that is a target value for a virtual steering angle of a virtual steering wheel of the trailer when the trailer is considered to be a single vehicle. In this case, the control device for articulated vehicles may be configured to calculate a limit value for the target virtual steering angle by substituting a value of a hitch angular velocity that is the time rate of change of 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, and a value of a maximum steering angular velocity that is the time rate of change of a maximum steering angle, which is the maximum physically possible steering angle of the steered wheels, into an equation of motion for a virtual steering angular velocity that is the time rate of change of the virtual steering angle.

[0015] According to this configuration, by limiting the time rate of change of the virtual steering angle, it is possible to suppress the occurrence of so-called overshoot, in which the virtual steering angle exceeds the target virtual steering angle. Furthermore, by limiting the time rate of change of the virtual steering angle, the time rate of change of the hitch angle is also limited. Since a sudden increase in the absolute value of the hitch angle is suppressed, it is possible to more appropriately suppress the occurrence of the jackknife phenomenon. As a result, it is possible to achieve more appropriate vehicle behavior.

[0016] The control device for the above-described articulated vehicles may be configured to calculate a limit value for the target virtual steering angle by substituting a value of a jackknife hitch angle, which is a boundary value of the hitch angle at which a jackknife phenomenon will occur, and a value of a maximum steering angle, which is the maximum value of the steering angle that can physically be attained for the steered wheels, into an equation of motion for the virtual steering angle.

[0017] According to this configuration, the target virtual steering angle is limited, thereby limiting the steering angle and, consequently, the hitch angle. As a result, the absolute value of the hitch angle is prevented from exceeding the absolute value of the jackknife hitch angle. This makes it possible to prevent the jackknife phenomenon from occurring. As a result, more appropriate vehicle behavior can be achieved. [Effects of the Invention]

[0018] According to the control device for articulated vehicles of the present invention, more appropriate vehicle behavior can be achieved. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a perspective view of an articulated vehicle equipped with a first embodiment of a control device for articulated vehicles. [Figure 2] 1 is a block diagram of a first embodiment of a control device for articulated vehicles. [Figure 3] 3 is a motion model of an articulated vehicle according to the first embodiment. [Figure 4] 3 is a motion model of a trailer according to the first embodiment. [Figure 5] 5 is a flowchart showing a procedure for limiting a control target value according to the first embodiment. [Figure 6] 4 is a graph showing an example of behavior of a control target value according to the first embodiment. [Figure 7] 1A is a graph showing the change over time in the steering angle of the front wheels of a tractor according to a comparative example, and FIG. 1B is a graph showing the change over time in the virtual steering angle in the comparative example. [Figure 8] 1A is a graph showing the change over time in the steering angle of the front wheels of the tractor according to the first embodiment, and FIG. 1B is a graph showing the change over time in the virtual steering angle according to the first embodiment. [Figure 9] 10 is a flowchart showing a procedure for limiting a control target value according to a second embodiment. [Figure 10]1A is a graph showing the change over time in the steering angle of the front wheels of a tractor according to a comparative example, and FIG. 1B is a graph showing the change over time in the hitch angle according to a comparative example. [Figure 11] 10(a) is a graph showing the change over time in the steering angle of the front wheels of the tractor according to the second embodiment, and FIG. 10(b) is a graph showing the change over time in the hitch angle according to the second embodiment. [Figure 12] FIG. 10 is a front view of a dial according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0020] First Embodiment 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.

[0021] 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.

[0022] 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.

[0023] As shown in FIG. 2, the tractor 11 has a display device 20, a power 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.

[0024] The power 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] <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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] When reverse assist control is being executed, the control device 42 controls the reverse path of the combination vehicle 10 via the power steering device 30 so that the combination vehicle 10 moves in the reverse direction or along the reverse path specified by the operator.

[0036] 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 electric signal S1 generated by the input device 41, that is, 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

[0037] 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.

[0038] 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.

[0039] <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.

[0040] 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 : 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.

[0041] 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.

[0042] The virtual steering angle α2 of the trailer 12 is expressed by the following equation 1.

[0043]

number

[0044] 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.

[0045] <Jackknife suppression processing> The control device 42 has a function to suppress the occurrence of a jackknife phenomenon, which is a phenomenon in which the connection portion between the tractor 11 and the trailer 12 bends significantly when the articulated vehicle 10 is reversed.

[0046] The control device 42 starts the execution of the jackknife suppression process when, for example, the operator performs an operation to start the 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 jackknife suppression process is a process for suppressing the occurrence of a jackknife phenomenon. However, the control device 42 may also start the execution of the jackknife suppression process when the shift range of the transmission mounted on the tractor 11 is switched to the reverse position. The control device 42 executes the jackknife suppression process in accordance with a program stored in a storage device (not shown) of the control device 42.

[0047] As shown in the flowchart of FIG. 5, first, the control device 42 calculates the target virtual steering angle α2 * (Step S101) * is the target value of the virtual steering angle α2, which is an internal control variable of the control device 42.

[0048] The control device 42 calculates the target virtual steering angle α2 based on, for example, the electric signal S1 generated by the input device 41, that is, the operation amount or operation position of the dial 41A relative to the reference position of the dial 41A. * The control device 42 calculates, for example, the operation amount or operation position of the dial 41A and the target virtual steering angle α2* 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, * Calculate the following.

[0049] The control device 42 also controls the jackknife hitch angle β jk (Step S102) The jackknife hitch angle β jk is the boundary value of the hitch angle β at which the jackknife phenomenon occurs. jk Physically, the maximum steering angle α of the front wheels 11F of the tractor 11 is 1mx In this case, the hitch angle β is defined as the angle when the hitch angular velocity β(·), which is the time rate of change of the hitch angle β, becomes "0". "·" indicates time differentiation. Maximum steering angle α 1mx is the maximum value of the steering angle α1 of the front wheels 11F of the tractor 11 that can be physically taken.

[0050] The equation of motion for the hitch angular velocity β(·) is expressed as Equation 2 below.

[0051]

number

[0052] 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.

[0053] In Equation 2, the control device 42 multiplies the steering angle α1 by the maximum steering angle α 1mx and substitutes "0" for the hitch angular velocity β(·). After this, the control device 42 solves Equation 2 for the hitch angle β to obtain the jackknife hitch angle β jk get.

[0054] The control device 42 determines the jackknife hitch angle β calculated in the previous step S102. jk Based on this, the target virtual steering angle α2 * Angle limit value α for 2mx (Step S103). The control device 42 calculates the angle limit value α using the following formula 3. 2mx Calculate the following.

[0055]

number

[0056] However, "β jk " is the jackknife hitch angle. "l1" is the wheelbase of the tractor 11. "h1" is the distance between the rear wheel 11R of the tractor 11 and the hitch point C1. "α mx " is the maximum steering angle of the front wheels 11F of the tractor 11.

[0057] Next, the control device 42 calculates the target virtual steering angle α2 * The absolute value of the angle limit value α 2mx It is determined whether the absolute value of is smaller than (step S104). The control device 42 calculates the target virtual steering angle α2 calculated in the previous step S101. * The absolute value of the angle limit value α 2mx If it is not smaller than the absolute value of (NO in step S104), the process proceeds to step S105.

[0058] In step S105, the control device 42 calculates the target virtual steering angle α2 calculated in the previous step S101. * , the angle limit value α 2mx The control device 42 limits the angle limit value α 2mx The target virtual steering angle α2 is limited to * The final target virtual steering angle α2 used to control the behavior of the articulated vehicle 10 * Retain as.

[0059] The target virtual steering angle α2 calculated in the previous step S101 *The absolute value of the angle limit value α 2mx When the absolute value of the target virtual steering angle α2 calculated in the previous step S101 is smaller than the absolute value of the target virtual steering angle α2 (YES in step S104), * The final target virtual steering angle α2 used to control the behavior of the articulated vehicle 10 * and retain it.

[0060] Next, the control device 42 calculates the target virtual steering angular velocity α2 * Speed ​​limit value α for (·) 2mx (·) is calculated (step S106). * (·) is the target virtual steering angle α2 * The time rate of change of the target virtual steering angular velocity α2 * (·) is the target virtual steering angle α2 * is obtained by differentiating with respect to time.

[0061] Target virtual steering angular velocity α2 * (·) is expressed by the following equation 4.

[0062]

number

[0063] Here, "β(·)" is the hitch angular velocity. The hitch angular velocity β(·) can be calculated using the above equation 2. "α1" is the steering angle of the front wheels 11F of the tractor 11. "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. "α1(·)" is the steering angular velocity of the front wheels 11F of the tractor 11.

[0064] The steering angular velocity α1(·) in the second term on the right side of Equation 4 is the maximum steering velocity α 1mx By substituting (·), the target virtual steering angular velocity α2 * Speed ​​limit value α for 2mx (·) is obtained.

[0065] Note that when the value of the steering angle α1 does not change, the second term on the right-hand side of Equation 4 may be calculated as "0." Situations in which the value of the steering angle α1 does not change include, for example, when the front wheels 11F are maintained at the limit position of their physical range of motion, or when the value of the steering angle α1 corresponding to the straight-ahead state of the articulated vehicle 10 is "0."

[0066] Next, the control device 42 calculates the target virtual steering angular velocity α2 * The absolute value of the speed limit value α 2mx It is determined whether it is smaller than the absolute value of (·) (step S107). The control device 42 sets the target virtual steering angular velocity α2 * The absolute value of the speed limit value α 2mx If it is not smaller than the absolute value of (·) (NO in step S107), the process proceeds to step S108.

[0067] In step S108, the control device 42 calculates the target virtual steering angle α2 calculated in the previous step S101. * Target virtual steering angular velocity α2 based on * , the speed limit value α 2mx The control device 42 limits the speed limit value α 2mx The target virtual steering angular velocity α2 is limited to (·) * The final target virtual steering angular velocity α2 used to control the behavior of the articulated vehicle 10 * Retain as.

[0068] The control device 42 sets the target virtual steering angular velocity α2 * The absolute value of the speed limit value α 2mx When the absolute value of the target virtual steering angle α2 calculated in the previous step S101 is smaller than the absolute value of (·) (YES in step S107), * Target virtual steering angular velocity α2 based on * The final target virtual steering angular velocity α2 used to control the behavior of the articulated vehicle 10 * Retain as.

[0069] The control device 42 calculates the final target virtual steering angle α2, which is the control target value. *and the final target virtual steering angular velocity α2 * The behavior of the articulated vehicle 10 is controlled using the above (step S109).

[0070] <Behavior of control target value> Next, the target virtual steering angle α2, which is the control target value, * An example of the behavior will be described below. First, the target virtual steering angle α2 * and target virtual steering angular velocity α2 * A comparative example in which the angle limit value α (·) is not limited will be considered. In the comparative example, the angle limit value α 2mx The target virtual steering angle α2 exceeds the absolute value of * When is set, the target virtual steering angle α2 * For example, it changes as follows:

[0071] As shown by the characteristic line L1 in the graph of FIG. 6, when the execution of the reverse assist control is started (time t0), the target virtual steering angle α2 * The absolute value of is set from the initial value "0" to the current setting value α 21 * The setting value α 21 * is the angle limit value α 2mx The target virtual steering angle α2 is a value that exceeds the absolute value of * The absolute value of the speed limit value α 2mx (·) exceeding the target virtual steering angular velocity α2 * (·) increases. Target virtual steering angular velocity α2 * (·) is the target virtual steering angle α2 * The target virtual steering angle α2 is the amount of change per unit time in the absolute value of the target virtual steering angle α2. * The absolute value of the angle limit value α 2mx The absolute value of α will be exceeded. 21 * is reached (time t1).

[0072] Next, the target virtual steering angle α2 * and target virtual steering angular velocity α2 *In this embodiment, the angle limit value α (·) is set by operating the dial 41A. 2mx The target virtual steering angle α2 exceeds the absolute value of * When is set, the target virtual steering angle α2 * changes as follows:

[0073] As shown by the characteristic line L2 in the graph of FIG. 6, when the execution of the reverse assist control is started (time t0), the target virtual steering angle α2 * The absolute value of is set from the initial value "0" to the current setting value α 21 * However, the target virtual steering angle α2 * The absolute value of the speed limit value α 2mx The target virtual steering angular velocity α2 is limited to (·) * (·). That is, the slope of the characteristic line L2 is smaller than the slope of the characteristic line L1. * The absolute value of the angle limit value α 2mx (time t2) The absolute value of the current setting value α 21 * is the angle limit value α 2mx Although the absolute value of the target virtual steering angle α2 * The absolute value of the angle limit value α 2mx is kept limited to the absolute value of

[0074] <Operation of the First Embodiment> Next, the operation of the first embodiment will be described. As an example, the articulated vehicle 10 makes a reverse right turn and then a reverse left turn. The turning radius is the same when making a reverse right turn and when making a reverse left turn. When making a turn, the maximum steering angle α, which is the limit value of the physical range of movement of the front wheels 11F of the tractor 11, can be adjusted by operating the dial 41A. 1mx Target steering angle α1 * is set.

[0075] As shown in the graph of FIG. 7(a), as the articulated vehicle 10 starts to turn backward to the right (at time t 10), the steering angle α1 of the front wheels 11F of the tractor 11 changes once in the negative direction, and then gradually increases in the positive direction. Eventually, the steering angle α1 reaches a constant positive value. After reaching the constant positive value, the steering angle α1 is maintained at the constant positive value for a predetermined period. The absolute value of the constant positive value is equal to the maximum steering angle α 1mx is a value less than the absolute value of

[0076] After the combination vehicle 10 has finished turning backward to the right, the combination vehicle 10 then starts turning backward to the left (time t 11 ) Steering angle α1 is the maximum steering angle α 1mx Then, the steering angle α1 starts increasing again in the positive direction from a constant positive value less than the absolute value of . This is due to, for example, a delay in the response of the steering angle α1 due to the physical constraints of the articulated vehicle 10. The steering angle α1 is 1mx After reaching this value, it then decreases in the negative direction and remains at a constant negative value.

[0077] Target virtual steering angular velocity α2 * In the comparative example where (·) is not limited, the virtual steering angle α2 changes as follows. As shown in the graph of FIG. 7(b), in the comparative example, when the articulated vehicle 10 starts to turn backward to the right (time t 10 ), as the steering angle α1 increases in the positive direction, the virtual steering angle α2 gradually increases in the positive direction. The virtual steering angle α2 is a positive target virtual steering angle α2 * After exceeding the positive direction, it then decreases in the negative direction, and eventually reaches a positive target virtual steering angle α2 * The virtual steering angle α2 reaches the positive target virtual steering angle α2 * After reaching the target virtual steering angle α2, the positive target virtual steering angle α2 is maintained until the reverse right turn of the articulated vehicle 10 is completed. * is maintained.

[0078] After the combination vehicle 10 has finished turning backward to the right, the combination vehicle 10 then starts turning backward to the left (time t 11 ) The virtual steering angle α2 is the positive target virtual steering angle α2 * The virtual steering angle α2 gradually decreases in the negative direction from the negative target virtual steering angle α2 *After going too far in the negative direction, it then reverses to the positive direction, and eventually reaches a negative target virtual steering angle α2 * The virtual steering angle α2 is a negative target virtual steering angle α2 * After reaching the negative target virtual steering angle α2 * is maintained.

[0079] As shown in the graph of Fig. 7(b), in the comparative example, an overshoot of the virtual steering angle α2 occurs. The overshoot occurs when the virtual steering angle α2, which is the control amount, exceeds the target virtual steering angle α2, which is the target value. * Due to physical constraints of the articulated vehicle 10, there is a response delay in the steering angle α1 and the hitch angle β. * When the steering angle α1 changes suddenly, the target steering angle α1 * In addition, there is a risk that the target hitch angle β * When the hitch angle β changes suddenly, the target hitch angle β * There is a risk that the system will not be able to keep up with changes in the

[0080] In contrast, the target virtual steering angular velocity α2 * In the first embodiment where (·) is limited, the steering angle α1 and the virtual steering angle α2 change as follows. The prerequisites for the turning direction of the articulated vehicle 10 and the amount of operation of the dial 41A are the same as those in the previous comparative example. That is, the articulated vehicle 10 makes a reverse right turn and then a reverse left turn. The turning radius is the same when making a reverse right turn and when making a reverse left turn. Furthermore, when making a turn, the maximum steering angle α, which is the limit value of the physical range of movement of the front wheels 11F of the tractor 11, is adjusted by operating the dial 41A. 1mx Target steering angle α1 * is set.

[0081] As shown in Fig. 8(a), the steering angle α1 changes in the same way as in the comparative example shown in Fig. 7(a). As shown in Fig. 8(b), as the steering angle α1 increases in the positive direction, the virtual steering angle α2 gradually increases in the positive direction, and eventually reaches a positive target virtual steering angle α2 *Unlike the comparative example shown in FIG. 7(b), the virtual steering angle α2 reaches a positive target virtual steering angle α2 * The virtual steering angle α2 is a positive target virtual steering angle α2 * After reaching the target virtual steering angle α2, the positive target virtual steering angle α2 is maintained until the reverse right turn of the articulated vehicle 10 is completed. * is maintained.

[0082] After the combination vehicle 10 has finished turning backward to the right, the combination vehicle 10 then starts turning backward to the left (time t 11 ) The virtual steering angle α2 is the positive target virtual steering angle α2 * Then, the target virtual steering angle α2 gradually decreases in the negative direction. * Unlike the previous comparative example shown in FIG. 7(b), the virtual steering angle α2 is set to a negative target virtual steering angle α2 * The virtual steering angle α2 does not go too far in the negative direction. * After reaching the negative target virtual steering angle α2 * is maintained.

[0083] <Advantages of the First Embodiment> The first embodiment provides the following advantages. (1-1) The control device 42 sets the target virtual steering angle α2, which is the target value for the reverse control of the articulated vehicle 10. * The control device 42 is configured to execute a process for limiting the target virtual steering angle α2 * Angle limit value α for 2mx Set the target virtual steering angle α2 * is the angle limit value α 2mx By limiting the angle limit value α 2mx The target virtual steering angle α2 has an excessively large absolute value exceeding * Therefore, it is possible to suppress the calculation of the vehicle speed, thereby realizing a more appropriate vehicle behavior.

[0084] (1-2) Target virtual steering angle α2 * As the absolute value of the target virtual steering angle α2 increases, the absolute value of the steering angle α1 and therefore the absolute value of the hitch angle β also increases.* By limiting the absolute value of the steering angle α1, the absolute value of the hitch angle β can be limited. Therefore, the absolute value of the hitch angle β is limited to the jackknife hitch angle β. jk Therefore, the occurrence of the jackknife phenomenon can be suppressed while the reverse assist control of the articulated vehicle 10 is being executed. Ultimately, more appropriate vehicle behavior can be achieved. Jackknife hitch angle β jk is the threshold value for whether or not the jackknife phenomenon occurs.

[0085] (1-3) The control device 42 calculates the target virtual steering angle α2 * The control device 42 is configured to execute a process for limiting the time rate of change of the target virtual steering angle α2 * The time rate of change of the target virtual steering angular velocity α2 * Speed ​​limit value α for (·) 2mx (·) is set. Target virtual steering angular velocity α2 * (·) is the speed limit value α 2mx Therefore, the target virtual steering angle α2 * This prevents the virtual steering angle α2, which is an internal control variable of the control device 42, from changing at a rate that the control device 42 cannot keep up with. * This prevents overshooting, which results in more appropriate vehicle behavior.

[0086] (1-4) Target virtual steering angular velocity α2 * As the absolute value of (·) increases, the absolute value of the steering angular velocity α1(·) and therefore the absolute value of the hitch angular velocity β(·) also increases. * By limiting (·), the hitch angular velocity β(·) is limited. This limits the hitch angle β to the jackknife hitch angle β jkFurthermore, a sudden increase in the absolute value of the hitch angle β is prevented. Therefore, the occurrence of the jackknife phenomenon can be more appropriately prevented while reverse assist control is being executed for the articulated vehicle 10. Ultimately, more appropriate vehicle behavior can be achieved.

[0087] (1-5) The operator operates the input device 41 to set the target virtual steering angle α2 of the trailer 12. * 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.

[0088] <Second embodiment> Next, a second embodiment of a control device for articulated vehicles will be described. This embodiment basically has the same configuration as the first embodiment shown in FIGS. 1 to 4. Therefore, detailed descriptions of the same members and configurations as the first embodiment will be omitted. This embodiment differs from the first embodiment in that a hitch angle β is used as the internal control variable of the control device 42 instead of the virtual steering angle α2.

[0089] The control device 42 has a setting unit 42A and a control unit 42B. The setting unit 42A sets the target hitch angle β of the trailer 12 based on the electrical signal S1 generated by the input device 41, that is, the operation amount or operation position of the dial 41A relative to the reference position of the dial 41A. * Set the target hitch angle β * is the target value of the hitch angle β of the trailer 12. The setting unit 42A is configured to set, for example, the operation amount or operation position of the dial 41A and the target hitch angle β of the trailer 12. * The target hitch angle β corresponding to the operation amount or operation position of the dial 41A is calculated using a map that defines the relationship between the *The operator operates the dial 41A to calculate a target hitch angle β according to a desired reverse path along which the trailer 12 is to be reversed. * It is possible to specify

[0090] The control unit 42B determines the target hitch angle β set by the setting unit 42A. * , the hitch angle β detected by the hitch angle sensor 51, the vehicle speed V detected by the vehicle speed sensor 52, and the steering angle α1 detected by the steering angle sensor 30C are taken in.

[0091] The control unit 42B determines the target hitch angle β 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 hitch angle β of the trailer 12 in accordance with the target hitch angle β. * 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 hitch angle β of the trailer 12 to the target hitch angle β * In order to match the target steering angle α1 of the front wheels 11F, feedback control of the hitch angle β is performed. * Calculate the following.

[0092] <Jackknife suppression processing> Next, the procedure for jackknife suppression processing will be described. As shown in the flowchart of FIG. 9, first, the control unit 42B calculates the target hitch angle β * (Step S201) The target hitch angle β * is the target value of the hitch angle β as a controlled variable.

[0093] The control unit 42B calculates the target hitch angle β based on, for example, the electrical signal S1 generated by the input device 41, that is, the operation amount or operation position of the dial 41A relative to the reference position of the dial 41A. * The control unit 42B calculates, for example, the operation amount or operation position of the dial 41A and the target hitch angle β *The target hitch angle β corresponding to the operation amount or operation position of the dial 41A is calculated using a map that defines the relationship between the * Calculate the following.

[0094] In addition, the control unit 42B adjusts the jackknife hitch angle β jk (Step S202) The jackknife hitch angle β jk is the boundary value of the hitch angle β at which the jackknife phenomenon occurs. jk Physically, the maximum steering angle α of the front wheels 11F of the tractor 11 is 1mx In this case, the hitch angle β is defined as the angle when the hitch angular velocity β(·), which is the time rate of change of the hitch angle β, becomes "0". "·" indicates time differentiation. Maximum steering angle α 1mx is the maximum value of the steering angle α1 of the front wheels 11F of the tractor 11 that can be physically taken.

[0095] The equation of motion of the hitch angular velocity β(·) is expressed by the above-mentioned formula 2. In formula 2, the control unit 42B multiplies the steering angle α1 by the maximum steering angle α 1mx Then, the control unit 42B solves the equation 2 for the hitch angle β to obtain the jackknife hitch angle β jk get.

[0096] The control unit 42B determines the jackknife hitch angle β calculated in the previous step S202. jk Based on this, the target hitch angle β * Angle limit value β for mx (Step S203). mx is the upper limit value + β, which is the positive angle limit value jk and the negative angle limit, lower limit -β jk That is, the jackknife hitch angle β jk is the angle limit value β mx is set as

[0097] Next, the control unit 42B calculates the target hitch angle β * The absolute value of the angle limit value β mxIt is determined whether the absolute value of is smaller than (step S204). The control device 42 determines the target hitch angle β calculated in the previous step S201. * The absolute value of the angle limit value β mx If it is not smaller than the absolute value of (NO in step S204), the process proceeds to step S205.

[0098] In step S205, the control device 42 calculates the target hitch angle β calculated in the previous step S201. * , the angle limit value β mx The control device 42 limits the angle limit value β mx The target hitch angle β is limited to * is the final target hitch angle β used to control the behavior of the articulated vehicle 10. * Retain as.

[0099] The target hitch angle β calculated in the previous step S201 * The absolute value of the angle limit value β mx If the absolute value of the target hitch angle β calculated in the previous step S201 is smaller than the absolute value of * The value of is used to control the behavior of the articulated vehicle 10 as the final target hitch angle β * Retain as.

[0100] Next, the control device 42 calculates the target hitch angular velocity β * Speed ​​limit value β for (·) mx (·) is calculated (step S206). * (·) is the target hitch angle β * is the time rate of change of

[0101] The equation of motion for the hitch angular velocity β(·) is expressed by the above-mentioned Equation 2. Here, the value of "tan α1" in the second term of Equation 2, which includes the steering angle α1, is limited from the viewpoint of limiting the hitch angular velocity β(·) to suppress the steering speed of the front wheels 11F of the tractor 11. There is a correlation between the hitch angular velocity β(·) and the steering speed of the front wheels 11F.

[0102] When "α1>0", "tan(α1')" at the next time has the relationship shown in the following Equation 5.

[0103]

number

[0104] However, "α 1mx " is the maximum steering angle of the front wheels 11F of the tractor 11. 1mx (·)" is the maximum steering angle α 1mx The maximum steering angular velocity α is the time rate of change of the steering angular velocity α 1mx (·) is the maximum steering angle α of the front wheel 11F 1mx is obtained by differentiating with respect to time.

[0105] The second or third term in Equation 5 is used as a constraint on "tan α1." The third term in Equation 5 is a stronger constraint than the second term. By substituting the second or third term into Equation 2, the target hitch angular velocity β * Speed ​​limit value β for (·) mx (·) is obtained.

[0106] Next, the control device 42 calculates the target hitch angular velocity β * The absolute value of (·) is the speed limit value β mx It is determined whether it is smaller than the absolute value of (·) (step S207). Target hitch angular velocity β * (·) is the target hitch angle β calculated in the previous step S201. * is obtained by substituting the value of Equation 2 above.

[0107] The control device 42 determines the target hitch angular velocity β * The absolute value of (·) is the speed limit value β mx If it is not smaller than the absolute value of (·) (NO in step S207), the process proceeds to step S108.

[0108] In step S208, the control device 42 calculates the target hitch angle β calculated in the previous step S201. * Target hitch angular velocity β based on * (·) is the speed limit value β mx The control device 42 limits the speed limit value β mx The target hitch angular velocity β is limited to (·). * (·) is the final target hitch angular velocity β * Keep it as (·).

[0109] The control device 42 determines the target hitch angular velocity β * The absolute value of (·) is the speed limit value β mx If the absolute value of (·) is smaller than the absolute value of the target hitch angle β calculated in the previous step S201 (YES in step S207), * Target hitch angular velocity β based on * (·) is the final target hitch angular velocity β * Keep it as (·).

[0110] The control device 42 determines the final target hitch angle β * and the final target hitch angular velocity β * The behavior of the articulated vehicle 10 is controlled using (·) (step S209). <Behavior of control target value> Next, the target hitch angle β * An example of the behavior will be described below.

[0111] Target hitch angle β * and the target hitch angular velocity β * Consider a comparative example in which the angle limit value β (·) is not limited. In the comparative example, the angle limit value β is set by operating the dial 41A. mx The target hitch angle β exceeds the absolute value of * When is set, the target hitch angle β * For example, it changes as follows:

[0112] As shown by the characteristic line L1 in the graph of FIG. 6, when the execution of the reverse assist control is started (time t0), the target hitch angle β * The absolute value of is set from the initial value "0" to the current setting value β1 * The setting value β1 gradually increases. * is the angle limit value β mx The target hitch angle β is a value that exceeds the absolute value of * The absolute value of the speed limit value β mx The target hitch angular velocity β exceeds (·) * (·) increases. The target hitch angular velocity β * (·) is the target hitch angle β * The target hitch angle β is the amount of change in the absolute value of the target hitch angle β per unit time, and indicates the slope of the characteristic line L1. * The absolute value of the angle limit value β mx The absolute value of β1 will be exceeded. * is reached (time t1).

[0113] In contrast, the target hitch angle β * and the target hitch angular velocity β * In this embodiment, the angle limit value β (·) is set by operating the dial 41A. mx The target hitch angle β exceeds the absolute value of * When is set, the target hitch angle β * changes as follows:

[0114] As shown by the characteristic line L2 in the graph of FIG. 6, when the execution of the reverse assist control is started (time t0), the target hitch angle β * The absolute value of is set from the initial value "0" to the current setting value β1 * However, the target hitch angle β * The absolute value of the speed limit value β mx The target hitch angular velocity β is limited to (·). * (·). That is, the slope of the characteristic line L2 is smaller than the slope of the characteristic line L1. Target hitch angle β * The absolute value of the angle limit value β mx The absolute value of this setting β1 is reached (time t2).* is the angle limit value β mx Although the absolute value of the target hitch angle β * The absolute value of the angle limit value β mx is kept limited to the absolute value of

[0115] <Operation of the second embodiment> Next, the operation of the second embodiment will be described. As an example, the articulated vehicle 10 makes a reverse right turn and then a reverse left turn. The turning radius is the same when making a reverse right turn and when making a reverse left turn. When making a turn, the maximum steering angle α, which is the limit value of the physical range of movement of the front wheels 11F of the tractor 11, can be adjusted by operating the dial 41A. 1mx Target steering angle α1 * is set.

[0116] As shown in the graph of FIG. 10(a), as the articulated vehicle 10 starts to turn backward to the right (at time t 10 ), the steering angle α1 of the front wheels 11F of the tractor 11 changes once in the negative direction, and then gradually increases in the positive direction. Eventually, the steering angle α1 reaches a constant positive value. After reaching the constant positive value, the steering angle α1 is maintained at the constant positive value for a predetermined period. The absolute value of the constant positive value is equal to the maximum steering angle α 1mx is a value less than the absolute value of

[0117] After the combination vehicle 10 has finished turning backward to the right, the combination vehicle 10 then starts turning backward to the left (time t 11 ) Steering angle α1 is the maximum steering angle α 1mx Then, the steering angle α1 starts increasing again in the positive direction from a constant positive value less than the absolute value of . This is due to, for example, a delay in the response of the steering angle α1 due to the physical constraints of the articulated vehicle 10. The steering angle α1 is 1mx After reaching this value, it then decreases in the negative direction and remains at a constant negative value.

[0118] Target hitch angular velocity β * In the comparative example where (·) is not restricted, the hitch angle β changes as follows: As shown in the graph of FIG. 10(b), in the comparative example, when the articulated vehicle 10 starts to turn backward to the right (time t 10 ), as the steering angle α1 increases in the positive direction, the hitch angle β gradually increases in the negative direction. The hitch angle β is * After exceeding the negative direction, it then increases in the positive direction, and eventually reaches the negative target hitch angle β * The hitch angle β is the negative target hitch angle β * After reaching the target hitch angle β, the negative target hitch angle β is * is maintained.

[0119] After the combination vehicle 10 has finished turning backward to the right, the combination vehicle 10 then starts turning backward to the left (time t 11 ). The hitch angle β is the negative of the target hitch angle β * The hitch angle β gradually increases in the positive direction from the positive target hitch angle β * After exceeding the positive direction, it then changes to the negative direction, and eventually reaches the positive target hitch angle β * The hitch angle β reaches the positive target hitch angle β * After reaching the positive target hitch angle β * is maintained.

[0120] As shown in the graph of Fig. 10(b), in the comparative example, an overshoot of the hitch angle β occurs. The overshoot occurs when the hitch angle β, which is a controlled variable, exceeds the target hitch angle β, which is a target value. * Due to physical constraints of the articulated vehicle 10, there is a response delay in the steering angle α1 and the hitch angle β. * When the steering angle α1 changes suddenly, the target steering angle α1 * In addition, there is a risk that the target hitch angle β * When the hitch angle β changes suddenly, the target hitch angle β * There is a risk that the system will not be able to keep up with changes in the

[0121] Next, the target hitch angular velocity β *This embodiment, which limits (·), will be considered. In this embodiment, the steering angle α1 and hitch angle β change as follows. The prerequisites, such as the turning direction of the articulated vehicle 10 and the amount of operation of the dial 41A, are the same as those in the previous comparative example. That is, the articulated vehicle 10 makes a reverse right turn, and then a reverse left turn. The turning radius when making a reverse right turn is the same as when making a reverse left turn. Furthermore, when making a turn, the maximum steering angle α1, which is the limit value of the physical range of movement of the front wheels 11F of the tractor 11, is changed by operating the dial 41A. 1mx Target steering angle α1 * is set.

[0122] As shown in Fig. 11(a), the steering angle α1 changes in the same way as in the comparative example shown in Fig. 10(a). As shown in Fig. 11(b), as the steering angle α1 increases in the positive direction, the hitch angle β gradually increases in the negative direction, and eventually reaches the negative target hitch angle β * Unlike the comparative example shown in FIG. 10(b), the hitch angle β reaches a negative target hitch angle β * The hitch angle β is set to the negative target hitch angle β * After reaching the target hitch angle β, the negative target hitch angle β is * is maintained.

[0123] After the combination vehicle 10 has finished turning backward to the right, the combination vehicle 10 then starts turning backward to the left (time t 11 ). The hitch angle β is the negative of the target hitch angle β * Then, the angle gradually increases in the positive direction, and eventually reaches the positive target hitch angle β * Unlike the previous comparative example shown in FIG. 10(b), the hitch angle β reaches a positive target hitch angle β * The hitch angle β is the positive target hitch angle β * After reaching the positive target hitch angle β * is maintained.

[0124] <Advantages of the second embodiment> The second embodiment has the following advantages. (2-1) The control device 42 adjusts the target hitch angle β, which is the target value for the reverse control of the articulated vehicle 10. * The control device 42 is configured to execute a process for limiting the target hitch angle β * Angle limit value β for mx Set the target hitch angle β * is the angle limit value β mx By limiting the angle limit value β mx The target hitch angle β has an excessive value exceeding * Therefore, it is possible to suppress the calculation of the vehicle speed, thereby realizing a more appropriate vehicle behavior.

[0125] (2-2) Target hitch angle β * As the absolute value of increases, the absolute value of the hitch angle β increases. Therefore, the target hitch angle β * Therefore, the absolute value of the hitch angle β is limited by limiting the absolute value of the jackknife hitch angle β. jk Therefore, the occurrence of the jackknife phenomenon can be suppressed while reverse assist control is being executed for the articulated vehicle 10. Consequently, more appropriate vehicle behavior can be achieved.

[0126] (2-3) The control device 42 determines the target hitch angle β * The control device 42 is configured to execute a process for limiting the time rate of change of the target hitch angle β * The target hitch angular velocity β * Speed ​​limit value α for (·) 2mx (·) is set. The target hitch angular velocity β * (·) is the speed limit value α 2mx Therefore, the target hitch angle β * This prevents the hitch angle β, which is an internal control variable of the control device 42, from changing at a rate that the control device 42 cannot keep up with. * This prevents overshooting, which results in more appropriate vehicle behavior.

[0127] (2-4) Target hitch angular velocity β * As the absolute value of (·) increases, the absolute value of the hitch angular velocity β(·) also increases. Therefore, the target hitch angular velocity β * By limiting (·), the hitch angular velocity β(·) is limited. This limits the hitch angle β to the jackknife hitch angle β jk Therefore, the occurrence of the jackknife phenomenon can be more appropriately prevented while reverse assist control is being executed for the articulated vehicle 10. Consequently, more appropriate vehicle behavior can be achieved.

[0128] (2-5) The operator operates the input device 41 to set the target hitch angle β of the trailer 12. * By specifying the above, it is possible to control the backward movement of the trailer 12, which is a nonlinear and unstable system. Therefore, it is possible to more appropriately support the backward operation of the articulated vehicle 10.

[0129] <Other embodiments> The first and second embodiments may be modified as follows. When performing reverse assist control for articulated vehicles, the control device 42 may display various information on the screen of the display device 20. For example, the control device 42 displays at least one of the following information (B1) to (B3) on the screen of the display device 20.

[0130] (B1) Limit value of control target value The control device 42 may display the limit value for the control target value on the screen of the display device 20. In the first embodiment, the control device 42 calculates the target virtual steering angle α2 * The angle limit value α 2mx is displayed numerically on the screen of the display device 20. In the second embodiment, the control device 42 controls the target hitch angle β * Angle limit value β for mx is displayed numerically on the screen of the display device 20.

[0131] (B2) Limit range of control target value In the first embodiment, the control device 42 sets the target virtual steering angle α2 * The range in which the target virtual steering angle α2 is limited may be visually displayed on the screen of the display device 20. * The angle range in which the target hitch angle β is limited is visually displayed using two lines centered on the hitch point C1. In the second embodiment, the control device 42 * The range in which the target hitch angle β is limited may be displayed on the screen of the display device 20. For example, * The angular range to which is limited is visually displayed using two lines centered at the hitch point C1.

[0132] (B3) Virtual steering angle For example, the control device 42 may display a trailer model regarded as a single vehicle having virtual front wheels on the screen of the display device 20. The control device 42 displaces the virtual front wheels of the trailer model in accordance with changes in the virtual steering angle α2.

[0133] In the first embodiment, for example, the target virtual steering angle α2 * and the angle limit value α 2mx When the difference between the target hitch angle β and the target hitch angle β reaches a value less than the first threshold value, the operator of the articulated vehicle 10 may be notified of this. * and the angle limit value β mx When the difference between the first and second threshold values ​​reaches a value less than the second threshold value, the control device 42 may notify the operator of the combination vehicle 10 of this fact. The control device 42 may notify the operator of the combination vehicle 10 visually, for example, via the display device 20. The control device 42 may also notify the operator of the combination vehicle 10 auditorily, via an on-board speaker.

[0134] Furthermore, the control device 42 may be configured to notify the operator of the combination vehicle 10 of the fact that the control target value is approaching the limit value by appealing to the operator's tactile sense. As shown in FIG. 12, the input device 41 has, for example, a motor 41B. The motor 41B is connected to a dial 41A. The control device 42 applies torque to the dial 41A through control of the motor 41B. For example, when the control target value approaches the limit value, the control device 42 applies a reaction force F c The point when the control target value approaches the limit value is, for example, when the difference between the control target value and the limit value becomes less than a predetermined threshold value. c is a force in the direction opposite to the operation direction D1 of the dial 41A. In addition, the control device 42 controls the reaction force F c Furthermore, the control device 42 may gradually increase the value of the reaction force F so that it becomes difficult to rotate the dial 41A when the control target value reaches the limit value. c may be given to the dial 41A. The dial 41A is held at a virtual end position, which is the limit position of a virtual operation range.

[0135] When a steering mechanism of the type that connects the front wheels 11F and the steering wheel so that power can be transmitted is employed as the steering mechanism of the tractor 11, as in the first and second embodiments, the following configuration may be employed as the input device 41. For example, a configuration having a slider may be employed instead of the dial 41A described above. The slider may be a dedicated item for specifying the reverse direction or reverse route of the combination vehicle 10, or it may be a slider for operating other on-board equipment. If the slider is for operating other on-board equipment, the function of the slider is switched to function as the input device 41 when the reverse assist function of the combination vehicle 10 is switched from off to on.

[0136] In the first and second embodiments, a steer-by-wire type steering mechanism in which power transmission between the front wheels 11F and the steering wheel is cut off may be used as the steering mechanism of the tractor 11. In this case, the steering wheel may be used as the input device 41. This is because the front wheels 11F and the steering wheel can be moved independently of each other. The front wheels 11F of the tractor 11 are steered by driving a steering motor. In this case, when the reverse assist function of the combination vehicle 10 is switched from off to on, the function of the steering wheel is switched to function as the input device 41. The operator specifies the reverse direction or reverse route of the combination vehicle 10 by operating the steering wheel.

[0137] The trailer 12 can be considered a single vehicle with virtual front wheels. This feature can be utilized to build an automatic reverse system for the articulated vehicle 10. For example, in the first embodiment, given that the internal control variable of the control device 42 is the virtual steering angle α2 of the trailer 12, it is possible to apply existing automatic parking control for passenger cars to the automatic reverse control of the trailer 12. This eliminates the need to develop a new control system for making the trailer 12 follow the target trajectory. [Explanation of symbols]

[0138] 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 an articulated vehicle that, when the articulated vehicle is operated in reverse, assists the operation of the trailer in reverse by making a control amount follow a target value for reverse control that is set through a specific operation by an operator, A control device for articulated vehicles configured to execute a process for limiting the target value and a process for limiting a time rate of change of the target value, from the viewpoint of realizing appropriate vehicle behavior.

2. 2. The control device for articulated vehicles according to claim 1, wherein the control device is configured to execute a process for limiting the target value and a process for limiting a time rate of change of the target value, from the viewpoint of suppressing the occurrence of a jackknife phenomenon.

3. The target value is a target hitch angle, which is a target value of a hitch angle that is an angle formed between a center axis extending in the length direction of the tractor and a center axis extending in the length direction of the trailer, 3. A control device for articulated vehicles according to claim 1 or 2, configured to calculate a limit value for the time rate of change of the target hitch angle by substituting a maximum steering angle value, which is the maximum value of the steering angle of the steered wheels that can be physically attained, or a maximum steering angular velocity value obtained by differentiating the maximum steering angle, into an equation of motion for a hitch angular velocity, which is the time rate of change of the hitch angle.

4. a process of substituting zero as the value of the hitch angular velocity and the value of the maximum steering angle into an equation of motion for the hitch angular velocity and solving the equation for the hitch angle to calculate a jackknife hitch angle, which is a boundary value of the hitch angle at which a jackknife phenomenon occurs; 4. The control device for articulated vehicles according to claim 3, wherein the control device is configured to execute a process of setting the jackknife hitch angle as a limit value for the target hitch angle.

5. the target value is a target virtual steering angle that is a target value of a virtual steering angle of a virtual steering wheel of the trailer when the trailer is regarded as a single vehicle, 3. A control device for articulated vehicles according to claim 1 or 2, configured to calculate a limit value for the target virtual steering angle by substituting a value of a hitch angular velocity that is the rate of change over time of 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, and a value of a maximum steering angular velocity that is the rate of change over time of a maximum steering angle that is the maximum value of the steering angle of the steered wheels that can be physically attained, into an equation of motion for a virtual steering angular velocity that is the rate of change over time of the virtual steering angle.

6. 6. A control device for articulated vehicles according to claim 5, configured to calculate a limit value for the target virtual steering angle by substituting a value of a jackknife hitch angle, which is a boundary value of the hitch angle at which a jackknife phenomenon will occur, and a value of a maximum steering angle, which is the maximum value of the steering angle that can physically be obtained, into an equation of motion for the virtual steering angle.

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