Control device for connected vehicles

Abstract

To provide a controller for a combination vehicle, capable of further appropriately estimating the length of a trailer.SOLUTION: A combination vehicle includes a tractor with a steering wheel and a trailer towed by a tractor. A controller for the combination vehicle includes an estimation section 42C. The estimation section 42C estimates a length of the trailer on the basis of a numerical expression including a virtual steering angle speed in a parameter. The numerical expression is obtained by solving a coalition equation of an equation of motion of a hitch angle speed which is a time change rate of a hitch angle β and an equation of motion of a virtual steering angle speed which is a time change rate of a virtual steering angle α2 of the trailer, for determining the length of the trailer.SELECTED DRAWING: Figure 5

Description

[Technical Field]

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

[0002] Conventionally, there exist articulated vehicles in which a trailer is coupled to a vehicle serving as a tractor. The system disclosed in Patent Document 1 has a function of automatically determining the dimensions of the trailer. The dimensions of the trailer are used, for example, to control the behavior of the trailer. The system estimates the dimensions of the trailer using a mathematical model of the vehicle and trailer. The mathematical model includes a motion model, a static model, or a dynamic model. The dimensions of the trailer include the length of the trailer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] US Patent Application Publication No. 2019 / 0322317 Summary of the Invention [Problem to be solved by the invention]

[0004] A control device for an articulated vehicle is required to more appropriately estimate the length of the trailer. [Means for solving the problem]

[0005] A control device for an articulated vehicle that solves the above problem is a control device for 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 has an estimating unit. The estimating unit estimates the length of the trailer based on a mathematical formula obtained by solving, for the length of the trailer, simultaneous equations of motion for a hitch angular velocity that is the time rate of change of the hitch angle, and for a virtual steering angular velocity that is the time rate of change of a virtual steering angle of the trailer, the mathematical formula including the virtual steering angular velocity as a parameter.

[0006] The hitch angle is the angle between the center axis extending along the length of the tractor and the center axis extending along the length of the trailer, and the virtual steering angle is the steering angle of the virtual steering wheels of the trailer when the trailer is considered as a single vehicle.

[0007] According to this configuration, the parameters of the mathematical formula representing the trailer length include the virtual steering angular velocity. The virtual steering angle is the steering angle of a virtual steering wheel of the trailer when the trailer 12 is considered to be a single vehicle. Therefore, by using the virtual steering angle, the trailer length can be appropriately estimated in a manner similar to that of a standard passenger car. Furthermore, the virtual steering angular velocity changes in response to the steering of the operator of the articulated vehicle. Therefore, by using the virtual steering angular velocity, the trailer length can be appropriately estimated at an earlier timing relative to the steering of the operator. Furthermore, by using the virtual steering angular velocity, the trailer length can be more quickly estimated in situations that include the period immediately after the articulated vehicle starts to turn.

[0008] In the control device for an articulated vehicle described above, the estimation section may estimate the length of the trailer when the articulated vehicle starts to turn. When the articulated vehicle is traveling straight, the steering angle of the tractor's steering wheels, the virtual steering angle of the trailer, and the hitch angle are all zero. This could make it impossible to properly estimate the trailer length. In this regard, with the above configuration, the trailer length is estimated when the articulated vehicle starts to turn, making it possible to more properly estimate the trailer length.

[0009] In the above-described control device for articulated vehicles, the trailer has wheels, and when the virtual steering wheels of the trailer are viewed as virtual front wheels of the trailer and the wheels are viewed as virtual rear wheels of the trailer, the estimation unit may estimate a virtual wheelbase of the trailer, which is the axle distance between the virtual front wheels and the virtual rear wheels of the trailer, as the length of the trailer.

[0010] The virtual wheelbase of the trailer is a value that reflects the length of the trailer, so the virtual wheelbase of the trailer can be estimated as the length of the trailer. In the control device for articulated vehicles described above, the estimation unit may estimate the length of the trailer after confirming that division by zero does not occur in the formula.

[0011] Dividing a number by zero, or division by zero, is an undefined operation in computer numerical calculations. By verifying that division by zero does not occur in the formula and then estimating the length of the trailer, it is possible to prevent the calculation process from failing, for example.

[0012] In the above-mentioned control device for articulated vehicles, the trailer length may be one of the control parameters used to control the behavior of the articulated vehicles. The control device for articulated vehicles may also have a processing unit. When the trailer length is estimated by the estimating unit, the processing unit executes processing to gradually change the value of the trailer length as the control parameter from a previous value to a current estimated value.

[0013] This configuration prevents sudden changes in the value of the trailer length as a control parameter. [Effects of the Invention]

[0014] According to the present invention, the length of the trailer can be more appropriately estimated. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a perspective view of an articulated vehicle equipped with an embodiment of a control device for articulated vehicles; [Figure 2] FIG. 2 is a block diagram of an embodiment of a control device for articulated vehicles. [Figure 3] 3 shows a motion model of an articulated vehicle according to one embodiment. [Figure 4]3 shows a trailer motion model according to one embodiment. [Figure 5] FIG. 2 is a block diagram of a trailer length estimation unit according to an embodiment. [Figure 6] 4 is a flowchart showing a trailer length estimation process according to an embodiment. [Figure 7] (a) is a graph showing the change in steering angle of the front wheels of the tractor from the start of turning to the end of turning of the articulated vehicle, (b) is a graph showing the change in hitch angle from the start of turning to the end of turning of the articulated vehicle, and (c) is a graph showing the change in trailer length before and after the articulated vehicle starts turning. [Figure 8] (a) is a graph showing a comparison example of changes in the estimated trailer length over the period from the start of turning to the end of turning of the articulated vehicle, (b) is a graph showing changes in the steering angle of the tractor's front wheels over the period from the start of turning to the end of turning of the articulated vehicle, (c) is a graph showing changes in the hitch angle over the period from the start of turning to the end of turning of the articulated vehicle, (d) is a graph showing changes in hitch angular velocity over the period from the start of turning to the end of turning of the articulated vehicle, and (e) is a graph showing changes in vehicle speed over the period from the start of turning to the end of turning of the articulated vehicle. [Figure 9] 10 is a graph showing changes in the estimated trailer length over a period from the start to the end of a turn of an articulated vehicle according to one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0016] An 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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 str The 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] <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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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

[0033] 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.

[0034] 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.

[0035] <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.

[0036] 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.

[0037] 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.

[0038] The virtual steering angle α2 of the trailer 12 is expressed by the following equation 1.

[0039]

number

[0040] 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.

[0041] <Supplementary explanation of the configuration of the control device 42> Next, the configuration of the control device 42 will be further explained. The control device 42 has the function of using control parameters to control the behavior of the articulated vehicle 10. The control parameters are stored in a storage device of the control device 42. The control parameters include vehicle specifications. The vehicle specifications include the length of the trailer 12. A variety of trailers 12 of different lengths are coupled to the tractor 11. For this reason, the control device 42 has the function of estimating the length of the trailer 12.

[0042] As shown in Fig. 5, the control device 42 has an estimating unit 42C. The estimating unit 42C estimates the length of the trailer 12 based on the state quantities and vehicle specifications of the articulated vehicle 10. The estimating unit 42C has a virtual steering angle calculating unit 42C1 and a trailer length calculating unit 42C2.

[0043] The virtual steering angle calculation unit 42C1 calculates the virtual steering angle α2. The virtual steering angle calculation unit 42C1 receives the vehicle speed V detected by the vehicle speed sensor 52, the steering angle α1 of the front wheels 11F detected by the steering angle sensor 30C, and the hitch angle β detected by the hitch angle sensor 51. The virtual steering angle calculation unit 42C1 also receives vehicle specifications required for calculating the virtual steering angle α2. The vehicle specifications include the wheelbase 11 of the tractor 11 and the distance h1 between the rear wheels 11R of the tractor 11 and the hitch point C1. The vehicle specifications are stored in the storage device of the control device 42. The virtual steering angle calculation unit 42C1 calculates the virtual steering angle α2 by applying the vehicle speed V, the steering angle α1 of the front wheels 11F, the hitch angle β, and the vehicle specifications to the above-mentioned Equation 1.

[0044] The trailer length calculation unit 42C2 calculates the length of the trailer 12. The trailer length calculation unit 42C2 calculates the virtual wheelbase l2 of the trailer 12 as the length of the trailer 12. The virtual wheelbase l2 is the distance between the virtual front wheels (= hitch point C1) of the trailer 12 and the wheels 12R serving as rear wheels. The virtual wheelbase l2 is a value that reflects the body length of the trailer 12. The longer the virtual wheelbase l2, the longer the overall body length of the trailer 12 will necessarily be.

[0045] Trailer length calculation unit 42C2 receives virtual steering angle α2 calculated by virtual steering angle calculation unit 42C1, vehicle speed V detected by vehicle speed sensor 52, steering angle α1 of front wheels 11F detected by steering angle sensor 30C, and hitch angle β detected by hitch angle sensor 51. Virtual steering angle calculation unit 42C1 also receives vehicle specifications required to calculate the length of trailer 12. The vehicle specifications include wheelbase l1 of tractor 11 and distance h1 between rear wheels 11R of tractor 11 and hitch point C1. Trailer length calculation unit 42C2 calculates estimated trailer length l2^ based on vehicle speed V, steering angle α1 of front wheels 11F, hitch angle β, virtual steering angle α2, and vehicle specification values. "^" indicates an estimated value.

[0046] Trailer length calculation unit 42C2 calculates estimated trailer length l2^ using Equation 4 obtained from the following Equations 2 and 3. Equation 2 is the equation of motion for the hitch angular velocity β(·), which is the time rate of change of the hitch angle β. The dot "·" indicates time differentiation.

[0047]

number

[0048] 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.

[0049] Equation 3 is the equation of motion for the virtual steering angular velocity α2(·), which is the time rate of change of the virtual steering angle α2. The dot "·" indicates time differentiation.

[0050]

number

[0051] where "β(·)" is the hitch angular velocity, "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, and "α1" is the steering angle of the front wheel 11F of the tractor 11.

[0052] By solving the simultaneous equations of Equation 2 and Equation 3 for the virtual wheel base l2 of the trailer 12, Equation 4 is obtained.

[0053]

number

[0054] "1 / denominator" in Equation 4 is a calculation coefficient. 5, the control device 42 has a processing unit 42D. The processing unit 42D executes predetermined processing based on the estimated trailer length l2^ calculated by the estimation unit 42C.

[0055] The length of the trailer 12 is one of the control parameters used to control the behavior of the articulated vehicle 10. The processing unit 42D executes processing to reflect the estimated trailer length l2^ calculated by the estimating unit 42C as a control parameter of the articulated vehicle 10. For example, when the trailer 12 is replaced, the estimated trailer length l2^ of the replaced trailer 12 is reflected in the control parameters of the articulated vehicle 10. The control device 42 can control the behavior of the articulated vehicle 10 based on the estimated trailer length l2^ of the replaced trailer 12. Therefore, it is possible to ensure behavior controllability of the articulated vehicle 10 even after the trailer 12 has been replaced.

[0056] The processing unit 42D may be configured to execute processing to suppress the occurrence of jackknife. Jackknife refers to a phenomenon in which the connection between the tractor 11 and the trailer 12 bends significantly when the combination vehicle 10 is reversed. The length of the trailer 12 affects the allowable range of the hitch angle β that leads to the occurrence of jackknife. For this reason, a limit value for changes in the hitch angle β may be set in the process of executing behavior control of the combination vehicle 10. The processing unit 42D executes processing to correct the limit value for changes in the hitch angle β to a more appropriate value, for example, in accordance with the estimated trailer length l2^ calculated by the estimating unit 42C.

[0057] When the processing unit 42D inputs the estimated trailer length l2^, it is possible that the hitch angle β has already reached a value within the jackknife range. The jackknife range is the angle range of the hitch angle β within which a jackknife phenomenon may occur. In this case, the processing unit 42D may execute processing to notify the operator of the combination vehicle 10 that a jackknife phenomenon may occur. The processing unit 42D may, for example, generate a notification command signal to the display device 20. The operator of the combination vehicle 10 can visually recognize that a jackknife phenomenon may occur.

[0058] The processing unit 42D may also be configured to alert the operator of the combination vehicle 10 that there is a risk of jackknife occurring by emitting a sound through an on-board speaker. The operator of the combination vehicle 10 can recognize through their hearing that there is a risk of jackknife occurring.

[0059] The processing unit 42D may be configured to execute processing for controlling the behavior of the combination vehicle 10. For example, if there is a risk of jackknife occurring, the processing unit 42D may execute processing for temporarily slowing down or stopping the combination vehicle 10. The processing unit 42D generates a deceleration command signal or a stop command signal for the braking device of the combination vehicle 10. By temporarily slowing down or stopping the combination vehicle 10 through operation of the braking device, it is possible to prevent the occurrence of jackknife.

[0060] The processing unit 42D may be configured to execute processing for detecting an abnormality in the combination vehicle 10. An abnormality may include, for example, the trailer 12 not being coupled to the tractor 11. The operator of the combination vehicle 10 may mistakenly believe that the trailer 12 is coupled to the tractor 11 when in fact the trailer 12 is not coupled to the tractor 11. An abnormality may also include the hitch angle sensor 51 not being electrically connected to the control device 42. For example, a break in the signal line connecting the hitch angle sensor 51 and the control device 42 may be considered.

[0061] When the trailer 12 is not coupled to the tractor 11, the hitch angle β detected by the hitch angle sensor 51 does not change even if the steering angle α1 of the front wheels 11F changes. If the hitch angle sensor 51 is not electrically connected to the control device 42, the control device 42 cannot detect changes in the hitch angle β. Therefore, the trailer length calculation unit 42C2 calculates an estimated trailer length l2^ that is completely different in response to changes in the steering angle α1 of the front wheels 11F of the tractor 11. The processing unit 42D determines an abnormality based on, for example, the degree of deviation between the estimated trailer lengths l2^ for two different steering angles α1. When an abnormality is detected, the processing unit 42D generates a notification command signal for the display device 20, for example. The operator of the combination vehicle 10 can visually recognize the occurrence of an abnormality.

[0062] The processing unit 42D may notify the operator of the combination vehicle 10 that an abnormality has been detected by emitting a sound through an on-board speaker. The operator of the combination vehicle 10 can recognize that an abnormality has occurred through their hearing.

[0063] <Trailer length estimation procedure> Next, a description will be given of the procedure for estimating the trailer length by the control device 42. The control device 42 starts executing the trailer length estimation process, for example, when the vehicle power is turned on. The control device 42 executes the trailer length estimation process in accordance with a program stored in a storage device (not shown).

[0064] 6, the control device 42 determines whether the vehicle is turning (step S101). The vehicle is, for example, the tractor 11. For example, the control device 42 determines that the vehicle is turning when all of the following three conditions (C1) to (C3) are met: The control device 42 determines that the vehicle is not turning when at least one of the three conditions (C1) to (C3) is not met.

[0065] C1.│V│≧V th C2.│α1│≧α 1th C3.│β│≧β th Where "V" is the vehicle speed. th " is a vehicle speed determination threshold value. "α1" is the steering angle of the front wheels 11F of the tractor 11. "α 1th " is the steering angle determination threshold value. "β" is the hitch angle. "β th " is the hitch angle determination threshold value. Vehicle speed determination threshold value V th , steering angle determination threshold α 1th , and the hitch angle determination threshold value β th is a criterion for determining the turning state of the vehicle and is set to a value greater than "0." When the vehicle is traveling straight, the steering angle α1 of the front wheels 11F and the hitch angle β are both "0."

[0066] The control device 42 waits until the vehicle starts turning (NO in step S101). When it is determined that the vehicle is turning (YES in step S101), the control device 42 calculates a virtual steering angle α2 (step S102). The control device 42 calculates the virtual steering angle α2 using the above-mentioned Equation 1.

[0067] Next, the control device 42 determines whether the trailer length can be calculated (step S103). The control device 42 checks whether division by zero occurs in the above formula 4. For example, the control device 42 checks whether the value of the denominator, which is the divisor, in the above formula 4 is "0". When formula 4 includes a division by "0", the control device 42 determines that the trailer length estimation calculation is not possible. This is because dividing a numerical value by "0", so-called division by zero, is an operation that cannot be defined in computer numerical calculations. When the control device 42 determines that the trailer length estimation calculation is not possible (NO in step S103), the control device 42 proceeds to the previous step S101.

[0068] The control device 42 determines that the trailer length can be calculated when the value of the denominator of Equation 4 is not "0" and when the denominator of Equation 4 does not include a portion that is divided by "0". When the control device 42 determines that the trailer length can be calculated (YES in step S103), it estimates and calculates the trailer length (step S104). The control device 42 calculates the estimated trailer length l2^ using Equation 4 above.

[0069] This completes the trailer length estimation process. <Changes in the state quantity of the articulated vehicle 10> Next, a description will be given of changes in the state quantities of the articulated vehicle 10 associated with the trailer length estimation process. The state quantities include the steering angle α1 of the front wheels 11F of the tractor 11 and the hitch angle β.

[0070] As shown in the graph in Figure 7(a), for example, when the combination vehicle 10 is traveling straight and starts to make a right reverse turn (time t1), the absolute value of the steering angle α1 of the front wheels 11F of the tractor 11 gradually increases in the positive direction and eventually reaches a predetermined value. The predetermined value is a value that corresponds to the turning radius of the combination vehicle 10. The absolute value of the steering angle α1 is maintained at a constant value for a period that corresponds to the length of the turning path. When the combination vehicle 10 finishes making a right reverse turn, the absolute value of the steering angle α1 gradually decreases toward "0", which corresponds to the combination vehicle 10 traveling straight. The combination vehicle 10 finishes making a left turn (time t2) when the absolute value of the steering angle α1 reaches "0".

[0071] As shown in the graph in Figure 7(b), when the articulated vehicle 10 starts to make a right reverse turn while traveling straight (time t1), the absolute value of the hitch angle β of the trailer 12 gradually increases in the negative direction and eventually reaches a predetermined value. The predetermined value is a value that corresponds to the turning radius of the articulated vehicle 10. The absolute value of the hitch angle β is maintained at a constant value for a period that corresponds to the length of the turning path. When the articulated vehicle 10 finishes making a right reverse turn, the absolute value of the hitch angle β gradually decreases toward "0", which corresponds to the state of the articulated vehicle 10 traveling straight. The articulated vehicle 10 finishes making a left turn when the absolute value of the hitch angle β reaches "0" (time t2).

[0072] The control device 42 begins executing the process for estimating the trailer length at the timing (time t1) when the combination vehicle 10 starts turning. The period during which it is possible to estimate the trailer length is the period during which the combination vehicle 10 is turning. The turning period is the period from time t1 when the combination vehicle 10 starts turning to time t2 when the combination vehicle 10 finishes turning.

[0073] As shown in the graph of FIG. 7(c), the control device 42 calculates the current estimated trailer length l obtained at the timing when the articulated vehicle 10 starts turning. 2new In other words, the control device 42 reflects the trailer length, which is one of the control parameters stored in the storage device, in the control parameter l. 2old ^From this trailer length l 2new Update to ^. Previous estimated trailer length l 2old ^ is the estimated trailer length used as one of the control parameters before the current estimation process was performed. The previous trailer length l 2old ^ includes, for example, the following three values ​​(E1) to (E3).

[0074] (E1) The initial value of the trailer length stored as a vehicle specification value in the storage device of the control device 42 (E2) Trailer length setting value set by the operator via the on-board input device (E3) The previous estimate of trailer length stored in the memory of the control device 42 In the example shown in Figure 7(c), the trailer length l 2new ^ is the previous trailer length l 2old This is due to the replacement of trailer 12, for example.

[0075] <Comparative Example> Next, a comparative example of the trailer length estimation process will be described. It is conceivable that trailer length calculation unit 42C2 calculates the trailer length using the following Equation 5. Equation 5 can be obtained by solving Equation 2 above for the virtual wheel base l2 of trailer 12.

[0076]

number

[0077] where "β" is the hitch angle. "β(·)" is the hitch angular velocity. "l1" is the wheelbase of the tractor 11. "l 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.

[0078] <Trailer length estimation accuracy in comparative example> Next, the estimation accuracy of the trailer length in the comparative example will be considered. The trailer length is the virtual wheelbase l2.

[0079] The prerequisites include the following five items (D1) to (D5). (D1) The offset of the sensors is removed. The sensors include a hitch angle sensor 51 and a vehicle speed sensor 52.

[0080] (D2) The wheelbase l1 of the tractor 11 is known. (D3) The distance h1 between the rear wheel 11R of the tractor 11 and the hitch point C1 is known. (D4) The road surface is flat and there is no disturbance from outside the articulated vehicle 10.

[0081] (D5) The articulated vehicle 10 needs to turn. It may be moving forward or backward. Here, as an example, we will consider a case where the articulated vehicle 10 makes a right turn while reversing. We will also consider two vehicle states with different imaginary wheelbases l2. The first vehicle state is a state of the articulated vehicle 10 in which the imaginary wheelbase l2 has a first value. The first value is, for example, 1.5 m. The second vehicle state is a state of the articulated vehicle 10 in which the imaginary wheelbase l2 has a second value. The second value is, for example, 2.8 m.

[0082] As shown in the graph of FIG. 8(b), the initial T ini In this state, the absolute value of the steering angle α1 of the front wheel 11F gradually increases in the positive direction. As shown in the graph of FIG. 8(c), the initial T ini , the absolute value of the hitch angle β gradually increases in the negative direction.

[0083] As shown in the graph of FIG. 8(d), the initial T ini In this case, the absolute value of the hitch angular velocity β(·) gradually increases in the positive direction. As shown in the graph of FIG. 8(e), the initial T ini In this case, the absolute value of the vehicle speed V gradually increases in the negative direction.

[0084] As shown in the graphs of Figures 8(b) to 8(e), the state variables of the articulated vehicle 10 change in roughly the same manner in a first vehicle state in which the virtual wheelbase l2 is a first value and a second vehicle state in which the virtual wheelbase l2 is a second value. However, the degree of change in each state variable differs slightly between the first vehicle state and the second vehicle state. The state variables include the steering angle α1 of the front wheels 11F, the hitch angle β, the hitch angular velocity β(·), and the vehicle speed V.

[0085] As shown in the graph of FIG. 8(a), the initial T ini In the second vehicle state, there is a negative value period in which the estimated trailer length l2^, which is the estimated value of the virtual wheelbase l2, becomes a negative value. The negative value of the estimated trailer length l2^ indicates that the estimation calculation of the virtual wheelbase l2 has not been performed correctly. This is because the value of the virtual wheelbase l2 never becomes a negative value. The negative value period ΔT2 in the second vehicle state is longer than the negative value period ΔT1 in the first vehicle state.

[0086] Initial T when the articulated vehicle 10 starts turning iniIn the first vehicle state where the virtual wheel base l2 is a first value, the estimated trailer length l2^, which is an estimated value of the virtual wheel base l2, changes suddenly from a negative value to a positive value. 21 After suddenly increasing to a value that deviates significantly in the positive direction relative to the first value l 21 , and then decreases rapidly to the first value l 21 reaches a value close to .

[0087] Initial T when the articulated vehicle 10 starts turning ini In the second vehicle state where the virtual wheel base l2 is the second value, the estimated trailer length l2^, which is the estimated value of the virtual wheel base l2, changes suddenly from a negative value to a positive value. 22 After a sudden increase to a value that deviates significantly in the positive direction relative to the second value l 22 and then decreases rapidly to a second value l 22 reaches a value close to .

[0088] However, after the articulated vehicle 10 in the second vehicle state starts turning, the value of the estimated trailer length l2^ becomes the second value l 22 The period from when the articulated vehicle 10 in the first vehicle state starts turning until the estimated trailer length l2^ reaches a value close to the first value l 21 is longer than the period it takes to reach a value close to .

[0089] From the above, when the virtual wheel base l2 of the trailer 12 is estimated using the above-mentioned Equation 5, in particular, the initial T ini In this case, it is difficult to accurately estimate the virtual wheelbase l2. As the value of the virtual wheelbase l2 increases, it takes more time to obtain an estimation result close to the true value of the virtual wheelbase l2. Also, as the value of the virtual wheelbase l2 increases, the accuracy of estimating the virtual wheelbase l2 decreases. In other words, the deviation between the true value of the virtual wheelbase l2 and the estimated value of the virtual wheelbase l2 becomes larger.

[0090] <Trailer length estimation accuracy in this embodiment> Next, the estimation accuracy of the virtual wheel base l2 in this embodiment will be considered. The preconditions are the same as those in the previous comparative example. That is, the preconditions include the five items (D1) to (D5) mentioned above. Also, as in the previous comparative example, we will consider the case where an articulated vehicle 10 in the first vehicle state makes a right turn while reversing, and the case where an articulated vehicle 10 in the second vehicle state makes a right turn while reversing.

[0091] Each state quantity of the articulated vehicle 10, namely the steering angle α1 of the front wheels 11F, the hitch angle β, the hitch angular velocity β(·), and the vehicle speed V, changes over time as shown in the graphs of Figures 8(b) to 8(e).

[0092] As shown in the graph of FIG. 9, the initial T ini In either the first vehicle state or the second vehicle state, there is no negative value period in which the estimated trailer length l2^, which is the estimated value of the virtual wheelbase l2, is a negative value. That is, in either the first vehicle state or the second vehicle state, there is no negative value period in which the initial T ini From this, it can be seen that the estimation calculation of the virtual wheel base l2 is performed correctly.

[0093] In the first vehicle state where the virtual wheel base l2 is a first value, the initial time T ini In this case, the estimated trailer length l2^, which is the estimated value of the virtual wheelbase l2, is calculated based on the first value l 21 The first value l is chosen so that 21 The estimated trailer length l2^ varies within a range close to the first value l 21 There is almost no significant deviation from this.

[0094] In the second vehicle state where the virtual wheel base l2 is a second value, the initial time T ini In this case, the estimated trailer length l2^, which is the estimated value of the virtual wheelbase l2, is calculated based on the second value l 22The second value l is chosen so that 22 The estimated trailer length l2^ varies within a range close to the second value l 22 There is almost no significant deviation from this.

[0095] From the above, by estimating the virtual wheel base l2 of the trailer 12 using the above-mentioned Equation 4, the initial T ini It can be seen that the virtual wheelbase l2 can be more appropriately estimated regardless of the value of the virtual wheelbase l2. For example, regardless of the value of the virtual wheelbase l2, an estimation result close to the true value of the virtual wheelbase l2 can be quickly obtained. Furthermore, regardless of the value of the virtual wheelbase l2, the estimation accuracy of the virtual wheelbase l2 can be ensured. In other words, the deviation between the true value of the virtual wheelbase l2 and the estimated value of the virtual wheelbase l2 becomes smaller.

[0096] <Effects of this embodiment> This embodiment has the following advantages. (1) As shown in Equation 4 above, the control device 42 estimates the length of the trailer 12 using the virtual steering angle α2 of the trailer 12. The virtual steering angle α2 is the steering angle of a virtual steering wheel of the trailer 12 when the trailer 12 is considered to be a single vehicle. Therefore, by using the virtual steering angle α2, the control device 42 can appropriately estimate the length of the trailer 12 in the same manner as for a standard passenger car.

[0097] (2) Furthermore, the virtual steering angle α2 of the trailer 12, and therefore the virtual steering angular velocity α2(·), change in response to steering by the operator of the combination vehicle 10. For this reason, by using the virtual steering angular velocity α2(·), the control device 42 can estimate the length of the trailer 12 at an earlier timing in response to steering by the operator. In other words, the responsiveness of the trailer length estimation to steering by the operator is improved.

[0098] (3) As shown in Equation 4 above, the control device 42 estimates the length of the trailer 12 using the virtual steering angular velocity α2(·), which is the time rate of change of the virtual steering angle α2 of the trailer 12. This makes it possible to more quickly estimate the length of the trailer 12 in situations that include the period immediately after the articulated vehicle 10 starts to turn. Even immediately after the trailer 12 has been replaced, the length of the trailer 12 can be appropriately estimated.

[0099] (4) The control device 42 estimates the length of the trailer 12 when the combination vehicle 10 starts to turn. This makes it possible to more accurately estimate the length of the trailer 12. This is because, when the combination vehicle 10 is turning, the absolute value of the steering angle α1 of the front wheels 11F of the tractor 11, the absolute value of the virtual steering angle α2 of the trailer 12, and the absolute value of the hitch angle β do not become 0. Incidentally, when the combination vehicle 10 is traveling straight, the value of the steering angle α1 of the front wheels 11F of the tractor 11, the value of the virtual steering angle α2 of the trailer 12, and the value of the hitch angle β become 0. This may make it difficult to accurately estimate the length of the trailer 12.

[0100] (5) The control device 42 estimates the virtual wheelbase l2 of the trailer 12 as the length of the trailer 12. The virtual wheelbase l2 is a value that reflects the length of the trailer 12. Therefore, the virtual wheelbase l2 of the trailer 12 can be estimated as the length of the trailer 12.

[0101] (6) The control device 42 estimates the length of the trailer 12 after confirming that division by zero does not occur in the above-mentioned formula 4. Dividing a numerical value by "0," so-called division by zero, is an operation that cannot be defined in computer numerical calculations. By estimating the length of the trailer 12 after confirming that division by zero does not occur in formula 4, it is possible to prevent, for example, the calculation process from failing.

[0102] (7) A more accurate estimated trailer length l2^ is reflected in the control parameters of the articulated vehicle 10. Therefore, even after the trailer 12 is replaced, it is possible to ensure behavior controllability of the articulated vehicle 10.

[0103] (8) An abnormality in the combination vehicle 10 is detected based on the estimated trailer length l2^. An abnormality may include, for example, the trailer 12 not being coupled to the tractor 11, or the hitch angle sensor 51 not being electrically connected to the control device 42. When an abnormality is detected, the operator of the combination vehicle 10 is notified of the abnormality through a visual or audible signal. The operator can then recognize that an abnormality has occurred and take action to resolve the abnormality.

[0104] (9) 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.

[0105] <Other embodiments> This embodiment may be modified as follows. As shown by the two-dot chain line in the graph of FIG. 7(c), when the processing unit 42D of the control device 42 estimates the length of the trailer 12, the processing unit 42D may gradually change the estimated value of the length of the trailer 12, which is one of the control parameters, from a previous value to a current value. The processing unit 42D performs, for example, a smoothing calculation. The smoothing calculation is expressed by the following equation.

[0106] Update value = current value + (target value - current value) x coefficient The target value is the current estimate of the length of the trailer 12 . Furthermore, the processing unit 42D may use a moving average to update the value of the length of the trailer 12, which is a control parameter. The moving average is an average value obtained by shifting the average value for each fixed period.

[0107] In this way, sudden changes in the value of the length of the trailer 12 as a control parameter can be suppressed. In other words, the value of the length of the trailer 12 as a control parameter changes gradually from the previous value to the current estimated value. This prevents sudden changes in the behavior of the combination vehicle 10.

[0108] The control device 42 may have a first filter and a second filter. The first filter and the second filter are, for example, low-pass filters. The first filter filters the electrical signal generated by the steering angle sensor 30C. The electrical signal indicates the steering angle α1 of the front wheels 11F of the tractor 11. Through the filtering, noise superimposed on the steering angle α1 as an electrical signal is removed. The second filter filters the electrical signal generated by the hitch angle sensor 51. The electrical signal indicates the hitch angle β. Through the filtering, noise superimposed on the hitch angle β as an electrical signal is removed.

[0109] The first filter and the second filter have the same cutoff frequency. The first filter has a dead band that sets values ​​near the zero point of the steering angle α1 to zero. The second filter has a dead band that sets values ​​near the zero point of the hitch angle β to zero. The width of the dead band of the first filter and the width of the dead band of the second filter are set to the same value. In this way, the phase of the electrical signal generated by the steering angle sensor 30C and the phase of the electrical signal generated by the hitch angle sensor 51 can be matched.

[0110] In the process of step S101 in the flowchart of FIG. 6, a condition (C4) may be added as a condition for determining whether the vehicle is turning. C4.│YR│≠0 Here, "YR" is the yaw rate of the vehicle. The yaw rate YR is detected, for example, by an on-board yaw rate sensor.

[0111] For example, when all four conditions (C1) to (C4) are met, the control device 42 determines that the vehicle is turning. By adding the condition (C4) to the turning determination conditions, the accuracy of the turning determination can be improved.

[0112] The length of the trailer 12 may be estimated using a Kalman filter based on a motion model of the articulated vehicle 10. This makes it possible to improve the accuracy of trailer length estimation and robustness against noise.

[0113] Depending on the product specifications, the process of step S101 in the flowchart of Fig. 6 may be omitted. In this case, when executing the process of estimating the trailer length, the control device 42 first calculates the virtual steering angle α2 of the trailer 12 (step S102). Also, the process of step S103 in the flowchart of Fig. 6 may be omitted. In this case, the control device 42 estimates the trailer length without determining whether the trailer length can be calculated.

[0114] The control unit 42B may have the functions of the estimation unit 42C and the processing unit 42D. [Explanation of symbols]

[0115] 10...Articulated vehicle 11...Tractor 11F...Front wheels (steering wheels) 12...Trailer 12R…Wheel 42...Control device 42C…Estimation part 42D...Processing section

Claims

1. A control device for 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, comprising: A control device for articulated vehicles having an estimating unit that estimates the length of the trailer based on a mathematical equation that includes the virtual steering angular velocity as a parameter, the mathematical equation being obtained by solving, for the length of the trailer, a simultaneous equation of motion for a hitch angular velocity that is the time rate of change of the hitch angle, which is the angle between a central axis extending along the length of the tractor and a central axis extending along the length of the trailer, and a mathematical equation for a virtual steering angular velocity that is the time rate of change of a virtual steering angle, which is the steering angle of a virtual steering wheel of the trailer when the trailer is considered to be a single vehicle.

2. The control device for an articulated vehicle according to claim 1 , wherein the estimation unit estimates the length of the trailer when the articulated vehicle starts to turn.

3. the trailer has wheels; When the virtual steering wheel of the trailer is regarded as a virtual front wheel of the trailer and the wheel is regarded as a virtual rear wheel of the trailer, 3. The control device for articulated vehicles according to claim 1 or 2, wherein the estimation unit estimates a virtual wheel base of the trailer, which is the distance between the axles of the virtual front wheels and the virtual rear wheels of the trailer, as the length of the trailer.

4. 4. The control device for articulated vehicles according to claim 1, wherein the estimation unit estimates the length of the trailer after confirming that division by zero does not occur in the formula.

5. the length of the trailer is one of the control parameters used to control the behavior of the combined vehicle; 5. A control device for articulated vehicles according to claim 1, further comprising a processing unit that executes processing to gradually change the value of the trailer length as the control parameter from a previous value to a current estimated value when the trailer length has been estimated by the estimation unit.

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