Connected vehicle control device, connected vehicle control method, and connected vehicle control program

Abstract

The connected vehicle is provided with a tractor and a trailer towed by the tractor. The linked vehicle is provided with an interface (80) for instructing a target virtual steering angle, which is a target value of the virtual steering angle, by a driver. The virtual steering angle is a variable indicating a traveling direction of a connection portion between the trailer and the tractor. The control device (50) is configured to execute: a process for acquiring a target virtual steering angle; a virtual steering angle control process for operating a steering system (60) of the connected vehicle in order to control the virtual steering angle to the target virtual steering angle; and a process for limiting the absolute value of the vehicle speed of the linked vehicle to a smaller side using the target virtual steering angle as an input during execution of the virtual steering angle control process. The linked vehicle is provided with an interface (80) for instructing a target virtual steering angle, which is a target value of the virtual steering angle, by a driver. The virtual steering angle is a variable indicating a traveling direction of a connection portion between the trailer and the tractor. The control device (50) is configured to execute: a process for acquiring a target virtual steering angle; a virtual steering angle control process for operating a steering system (60) of the connected vehicle in order to control the virtual steering angle to the target virtual steering angle; and a process for limiting the absolute value of the vehicle speed of the linked vehicle to a smaller side using the target virtual steering angle as an input during execution of the virtual steering angle control process.

Description

Technical Field

[0001] The present disclosure relates to a control device for a connected vehicle, a control method for a connected vehicle, and a control program for a connected vehicle. Background Art

[0002] For example, Patent Document 1 below describes a control device that assists reverse control of a coupled vehicle. When the coupled vehicle is traveling on a path with a small radius of curvature, the control device limits the absolute value of the vehicle speed in order to maintain control to keep the coupled vehicle traveling along the path.

[0003] Patent Document 1: U.S. Patent No. 10286950

[0004] In the above control device, the absolute value of the vehicle speed is limited according to the travel path of the connected vehicle, so that the traveling direction of the trailer can be maintained in the desired direction. However, the travel path of the connected vehicle itself is not a variable that directly determines the traveling direction of the trailer. Therefore, the controllability of controlling the traveling direction of the trailer is not necessarily high. Summary of the invention

[0005] In one technical solution of the present disclosure, a control device for a coupled vehicle is provided, the coupled vehicle having a tractor and a trailer towed by the tractor. The coupled vehicle has an interface for the driver to indicate a target virtual steering angle. The target virtual steering angle is a target value of a virtual steering angle. The virtual steering angle is a variable indicating the direction of travel of a coupling portion between the trailer and the tractor. The control device is configured to execute a target virtual steering angle acquisition process, a virtual steering angle control process, and a vehicle speed limit process. The target virtual steering angle acquisition process is a process for acquiring the target virtual steering angle. The virtual steering angle control process includes a process for operating a steering system of the coupled vehicle in order to control the virtual steering angle to the target virtual steering angle. The vehicle speed limit process is a process for limiting the absolute value of the vehicle speed of the coupled vehicle to a smaller side during the execution of the virtual steering angle control process, and includes a virtual steering angle dependent process for limiting the absolute value of the vehicle speed to a smaller side by taking the target virtual steering angle as an input.

[0006] In another technical solution of the present disclosure, a control method for a coupled vehicle is provided, the coupled vehicle having a tractor and a trailer towed by the tractor. The coupled vehicle has an interface for the driver to indicate a target virtual steering angle. The target virtual steering angle is a target value of a virtual steering angle. The virtual steering angle is a variable indicating the direction of travel of a coupling portion between the trailer and the tractor. The control method has the steps of executing a target virtual steering angle acquisition process, a virtual steering angle control process, and a vehicle speed limit process. The target virtual steering angle acquisition process is a process for acquiring the target virtual steering angle. The virtual steering angle control process includes a process for operating a steering system of the coupled vehicle in order to control the virtual steering angle to the target virtual steering angle. The vehicle speed limit process is a process for limiting the absolute value of the vehicle speed of the coupled vehicle to a smaller side during the execution of the virtual steering angle control process and includes a virtual steering angle dependent process for limiting the absolute value of the vehicle speed to a smaller side by taking the target virtual steering angle as an input.

[0007] In one technical solution of the present disclosure, a control program for a coupled vehicle is provided, which includes a tractor and a trailer towed by the tractor. The coupled vehicle includes an interface for the driver to indicate a target virtual steering angle. The target virtual steering angle is a target value of a virtual steering angle. The virtual steering angle is a variable indicating the direction of travel of the coupling portion between the trailer and the tractor. The control program includes instructions for causing a computer to execute a target virtual steering angle acquisition process, a virtual steering angle control process, and a vehicle speed limit process. The target virtual steering angle acquisition process is a process for acquiring the target virtual steering angle. The virtual steering angle control process includes a process for operating a steering system of the coupled vehicle in order to control the virtual steering angle to the target virtual steering angle. The vehicle speed limit process is a process for limiting the absolute value of the vehicle speed of the coupled vehicle to a smaller side during the execution of the virtual steering angle control process, and includes a virtual steering angle dependent process for limiting the absolute value of the vehicle speed to a smaller side by taking the target virtual steering angle as an input. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a perspective view showing a structure of a connected vehicle according to one embodiment.

[0009] Figure 2 Yes means Figure 1 A block diagram of the structure of a control system of a connected vehicle.

[0010] Figure 3 It means by Figure 2 A flowchart of the sequence of processes performed by a control device.

[0011] Figure 4 Yes means Figure 1 Diagram of a model of a connected vehicle.

[0012] Figure 5 It means by Figure 2 A flowchart of the sequence of processes performed by a control device.

[0013] Figure 6 It means by Figure 2 A flowchart of the sequence of processes performed by a control device.

[0014] Figure 7 It means by Figure 2 A flowchart of the sequence of processes performed by a control device.

[0015] Figure 8A to Figure 8C : is a diagram showing the relationship between the target virtual steering speed and the steering angular velocity according to this embodiment. DETAILED DESCRIPTION

[0016] Hereinafter, embodiments will be described with reference to the drawings.

[0017] "Structure connecting vehicles"

[0018] like Figure 1 As shown in FIG. 1 , the coupled vehicle 10 includes a tractor 20 and a trailer 30. The tractor 20 includes front wheels 22 and rear wheels 24. The front wheels 22 include two wheels, a right front wheel and a left front wheel, and the rear wheels 24 include two wheels, a right rear wheel and a left rear wheel. Figure 1 In FIG. 1 , a box-type trailer is exemplified as the trailer 30. The trailer 30 has wheels 32. The wheels 32 include two wheels, a right wheel and a left wheel.

[0019] The trailer 30 is connected to the rear part of the tractor 20 via a ball joint 40. The ball joint 40 is a member that connects the trailer 30 to the tractor 20 so as to be rotatable about a shaft 42. The shaft 42 extends in the height direction of the tractor 20.

[0020] exist Figure 2 , a part of the components provided by the tractor 20 is shown. Figure 2 As shown in FIG. 1 , the tractor 20 is provided with a control device 50. The control device 50 operates a steering system 60, a drive system 62, and a brake system 64 to control a control variable of the connected vehicle 10, which is a control object. The control variable is a vehicle speed, a driving direction, and a towing angle. The towing angle is an angle formed by the front-rear direction of the tractor 20 and the front-rear direction of the trailer 30.

[0021] The steering system 60 includes a steering actuator for steering the steering wheel. Figure 1 The front wheel 22 is shown. In addition, the steering control device that operates the steering actuator may also be included in the steering control system 60. In this case, "the control device 50 operates the steering control system 60" means that the control device 50 outputs a command signal to the steering control device.

[0022] The drive system 62 includes at least one of an internal combustion engine and a rotary electric machine as a thrust generating device of the vehicle. In addition, the drive system 62 may also include a drive control device that controls the internal combustion engine and the rotary electric machine. In this case, "the control device 50 operates the drive system 62" means that the control device 50 outputs a command signal to the drive control device.

[0023] The brake system 64 includes at least one of a device for decelerating the rotation of the wheel by friction and a device for decelerating the rotation of the wheel by converting the power of the wheel into electrical energy. In addition, the device for decelerating the rotation of the wheel by converting into electrical energy can also be shared with the rotating motor of the drive system. In addition, the brake system 64 can also include a brake control device that uses the device for decelerating the rotation of the wheel as a control object. In this case, "the control device 50 operates the brake system 62" means that the control device 50 outputs a command signal to the brake control device.

[0024] In order to control the control amount, the control device 50 refers to the steering angle α1 of the steering wheel detected by the steering angle sensor 70. The steering angle α1 is a value whose sign is positive for either right rotation or left rotation and whose sign is negative for the other. The steering angle α1 is the cutting angle of the tire. In addition, for example, in the case where the steering control system 60 has a rack and pinion mechanism, the steering angle sensor 70 can also be set as a sensor for detecting the pinion angle. However, in this case, the control device 50 performs a process of converting the pinion angle into the cutting angle of the tire. In the following, for the sake of convenience of explanation, even if the cutting angle of the tire is obtained by the above-mentioned conversion process, the obtained cutting angle of the tire will be regarded as the detection value of the steering angle sensor 70.

[0025] In addition, the control device 50 refers to the towing angle β detected by the towing angle sensor 72. The towing angle β can take a positive or negative sign depending on the angle between the direction from the rear to the front of the tractor 20 and the direction from the rear to the front of the trailer 30. For example, the sign of the towing angle β may be set to positive when the direction from the rear to the front of the trailer 30 is offset counterclockwise by less than 180° relative to the direction from the rear to the front of the tractor 20. In addition, the control device 50 refers to the wheel speeds ωw1 to ωw4 detected by the wheel speed sensor 74. The wheel speeds ωw1 and ωw2 are the rotation speeds of the right front wheel 22 and the rotation speed of the left front wheel 22, respectively. The wheel speeds ωw3 and ωw4 are the rotation speeds of the right rear wheel 24 and the rotation speed of the left rear wheel 24, respectively.

[0026] The control device 50 sets the control amount according to the operation state of the user interface 80. The user interface 80 is used to convey the user's intention, such as the selection of either the automatic driving or the manual driving, to the control device 50.

[0027] The control device 50 includes a PU 52 and a storage device 54. The PU 52 is a software processing device including at least one of a CPU, a GPU, and a TPU. A reverse assist program 54a is stored in the storage device 54. The reverse assist program 54a is a program that specifies an instruction for causing the PU 52 to execute a reverse assist process. The reverse assist process is a process for automatically performing a steering process of the steering wheel during reverse driving of the coupled vehicle 10. The reverse assist program 54a is a program for reducing the load on the driver for reverse driving.

[0028] That is, during the reverse travel of the coupled vehicle 10, even if the steering angle α1 of the tractor 20 remains the same, the behavior of the trailer 30 changes according to the towing angle β. Therefore, the reverse control requires a high driving skill. The reverse assist process based on the reverse assist program 54a is a process for assisting the driver by controlling the steering angle α1 of the tractor 20. However, the reverse assist process entrusts the driver with the instruction of the steering operation of the trailer 30. This is because, when the control device 50 also sets the steering operation of the trailer 30, the requirements for the control device 50 become higher. By entrusting part of the instructions to the driver, the reverse control can be performed by a relatively simple process.

[0029] "Steering maneuvers in reverse assist"

[0030] exist Figure 3 The sequence of the processes related to the steering operation in the reverse assist process is shown in FIG. 5. The reverse assist program 54a is repeatedly executed by the PU 52 at a predetermined cycle, for example. Figure 3In the following, the step number of each process is represented by a number with "S" at the beginning.

[0031] exist Figure 3 In the series of processes shown, first, PU52 determines whether it is the reverse assist mode (S10). When PU52 determines that it is the reverse assist mode (S10: Yes), it obtains the target virtual steering angle α2* input to the user interface 80 (S12). The target virtual steering angle α2* is a target value of the virtual steering angle α2. In the present embodiment, as an example, the virtual steering angle α2 is defined by the angle formed by the travel direction of the ball joint 40 relative to the front-rear direction of the trailer 30. The target virtual steering angle α2* is a variable representing the driver's instruction for the steering operation of the trailer 30.

[0032] Next, the PU 52 acquires the traction angle β detected by the traction angle sensor 72 (S14). In addition, the PU 52 acquires the steering angle α1 detected by the turning angle sensor 70 (S16).

[0033] Then, PU 72 takes the steering angle α1 and the traction angle β as inputs and calculates the virtual steering angle α2 (S18). Figure 4 , the reason for calculating the virtual steering angle α2 based on the steering angle α1 and the traction angle β is described.

[0034] Figure 4 A model of the connected vehicle 10 used in the present embodiment is shown. Figure 4 The model shown considers the pair of front wheels 22 of the tractor 20 as one front wheel C0, and the pair of rear wheels 24 of the tractor 20 as one rear wheel B1. That is, a two-wheel model is adopted for the tractor 20. In addition, the pair of wheels 32 of the trailer 30 are considered as one wheel B2. The angle formed by the line defined by the front wheel C0 and the connection point C1 and the line defined by the connection point C1 and the wheel B2 is the traction angle β. The connection point C1 is equivalent to Figure 1 The front wheel speed VC0 is a vector moving in the direction of the steering angle α1. The steering angle α1 is quantified as the angle between the moving direction of the front wheel C0 and the line defined by the front wheel C0 and the connection point C1. The direction of the vehicle speed V is parallel to the line defined by the front wheel C0 and the connection point C1. Figure 4 The angle formed by the line connecting the wheel B2 and the connection point C1 and the x direction is angle θ1. In addition, the angle formed by the line connecting the wheel B2 and the connection point C1 and the x direction is angle θ2. In addition, the distance l1 is the length between the front wheel C0 and the rear wheel B1. In addition, the distance h1 is the length between the rear wheel B1 and the connection point C1. The distance l2 is the length between the connection point C1 and the wheel B2.

[0035] According to the above definition, the direction of the speed VC1 of the connection point C1 relative to the direction from the wheel B2 to the connection point C1 is the virtual steering angle α2. If the angle γ1 formed by the direction of the speed VC1 of the connection point C1 relative to the direction from the connection point C1 to the front wheel C0 is used, the virtual steering angle α2 is "-(β-γ1)".

[0036] exist Figure 4 In the model shown, if the coordinates (xc0, yc0) of the front wheel C0, the coordinates (xb1, yb1) of the rear wheel B1, and the coordinates (xc1, yc1) of the connection point C1 are used, the following equations (c1) to (c3) are established.

[0037] VC0·cosα1=VB1…(c1)

[0038] xc0=xb1+l1·cosθ1…(c2)

[0039] xc1=xb1-h1·cosθ1…(c3)

[0040] When the equation obtained by differentiating both sides of the above equations (c2) and (c3) and equation (c1) are used, the following equation (c4) is obtained.

[0041] h1·tanα1+l1·tanγ1=0…(c4)

[0042] According to the above-mentioned formula (c4), the angle γ1 can be expressed by the steering angle α1. Therefore, the virtual steering angle α2 is expressed by the following formula (c5).

[0043] α2=-β-arctan{(h1 / l1)·tan(α1)}…(c5)

[0044] That is, the virtual steering angle α2 can be obtained from the traction angle β and the steering angle α1.

[0045] exist Figure 3 In the embodiment of the present invention, the above formula (c5) is described, but in fact, the PU 52 can also perform mapping calculation on the virtual steering angle α2 in the process of S18 by storing mapping data in the storage device 54. The mapping data uses the traction angle β and the steering angle α1 as input variables and uses the virtual steering angle α2 as an output variable.

[0046] Here, mapping data refers to a set of data of discrete values ​​of input variables and values ​​of output variables corresponding to the values ​​of the input variables. In addition, as long as the value of the input variable is consistent with any one of the values ​​of the input variables of the mapping data, the mapping operation can be processed by using the value of the output variable of the corresponding mapping data as the result of the operation. In addition, as long as the value of the input variable is inconsistent with any one of the values ​​of the input variables of the mapping data, the mapping operation can be processed by using the value obtained by interpolating the values ​​of multiple output variables included in the mapping data as the result of the operation. Alternatively, the mapping operation can also be processed by using the value of the output variable of the mapping data corresponding to the closest value among the values ​​of the multiple input variables included in the mapping data as the result of the operation when the value of the input variable is inconsistent with any one of the values ​​of the input variables of the mapping data.

[0047] Next, PU52 calculates the target steering angle α1* as the operation amount based on the feedback control, which uses the virtual steering angle α2 as the control amount and the target virtual steering angle α2* as the target value of the control amount (S20). The operation amount may be, for example, the output value of a proportional factor that uses the difference between the control amount and the target value as input. In addition, for example, the operation amount may also be the sum of the output value of an integral factor that uses the difference as input and the output value of a proportional factor. In addition, for example, the operation amount may also be the sum of the output value of a proportional factor that uses the difference as input, the output value of an integral factor, and the output value of a differential factor.

[0048] Next, the PU 52 calculates an operation amount for feedback control using the steering angle α1 as a control amount and the target steering angle α1* as a target control amount ( S22 ). Furthermore, the PU 52 operates the steering system 60 according to the operation amount ( S24 ).

[0049] In addition, when the processing of S24 is completed and a negative determination is made in the processing of S10, PU52 temporarily completes the processing of S24. Figure 3 A series of processing is shown.

[0050] "Vehicle speed control during reverse assist processing"

[0051] exist Figure 5 , the order of the processing related to the control of the vehicle speed in the reverse assist processing is shown. Figure 5 The processing shown is realized by the PU 52 repeatedly executing the reverse assist program 54a at a predetermined cycle, for example.

[0052] exist Figure 5In the series of processes shown, first, the PU 52 determines whether it is the reverse assist control mode (S30). When the PU 52 determines that it is the reverse assist control mode (S30: Yes), it obtains the user set vehicle speed Vu (S32). The user set vehicle speed Vu is the absolute value of the vehicle speed V of the connected vehicle 10 instructed by the driver through the input operation of the user interface 80. Next, the PU 52 calculates the upper limit value Vth of the absolute value of the vehicle speed corresponding to the current state of the connected vehicle 10 (S34).

[0053] Furthermore, PU52 substitutes the value obtained by multiplying the minimum value among the user-set vehicle speed Vu, the upper limit value Vth and the default value Vd by "-1" into the target vehicle speed V* (S36). The multiplication by "-1" is because the sign of the vehicle speed V during reverse is set to negative. The default value Vd is the upper limit value of the absolute value of the vehicle speed predetermined according to the stability margin. The larger the absolute value of the vehicle speed V, the smaller the stability margin in the reverse assist control mode. Therefore, the default value Vd is set so that the stability margin is greater than a constant value. In addition, the default value Vd takes into account the response characteristics of the steering control system 60.

[0054] Next, PU52 obtains the vehicle speed V (S38). Through PU52, at least one of the wheel speeds ωw1~ωw4 detected by the wheel speed sensor 74 is used as input to calculate the vehicle speed V. The vehicle speed V may be, for example, the average value of the wheel speeds ωw3 and ωw4. Next, PU52 calculates the operation amount for feedback control, which uses the vehicle speed V as the control amount and the target vehicle speed V* as the target value of the control amount (S40). The operation amount is the driving force of the connected vehicle 10. However, the sign of the driving force can be both positive and negative. When the sign of the driving force is positive when the connected vehicle 10 moves backward, the driving force represents the braking force of the connected vehicle 10. PU52 operates the drive system 62 and the braking system 64 according to the operation amount (S42).

[0055] In addition, when the processing of S42 is completed and a negative determination is made in the processing of S30, PU52 temporarily completes the processing of S42. Figure 5 A series of processing is shown.

[0056] exist Figure 6 as well as Figure 7 , details of the processing of S34 are shown.

[0057] like Figure 6As shown, PU52 obtains the target virtual steering angle α2* (S50). Next, PU52 uses the target virtual steering angle α2* as input and calculates the angle-dependent limit value Vth1 (S52). The angle-dependent limit value Vth1 is a variable that determines the upper limit value of the absolute value of the vehicle speed V required to maintain the controllability of the control with the virtual steering angle α2 as the control amount and the target virtual steering angle α2* as the target value of the control amount. PU52 sets the angle-dependent limit value Vth1 when the absolute value of the target virtual steering angle α2* is large to be less than the angle-dependent limit value Vth1 when the absolute value of the target virtual steering angle α2* is small. This process may also be a process in which PU52 performs mapping operation on the angle-dependent limit value Vth1 by pre-storing mapping data in the storage device 54. Here, the mapping data is data that uses the absolute value of the target virtual steering angle α2* as an input variable and the angle-dependent limit value Vth1 as an output variable. In addition, the value of the output variable included in the mapping data may also be monotonically decreasing according to the value of the input variable included in the mapping data.

[0058] Next, PU52 obtains the changing speed of the target virtual steering angle α2* (S54). Two or more sample values ​​of the target virtual steering angle α2* obtained at different timings are used as input, and PU52 calculates the changing speed of the target virtual steering angle α2*. Next, PU52 takes the absolute value of the changing speed of the target virtual steering angle α2* as input, and calculates the speed-dependent limit value Vth2 (S56). The speed-dependent limit value Vth2 is an upper limit value of the vehicle speed V for suppressing the following delay of the actual virtual steering angle α2 relative to the change of the target virtual steering angle α2*. PU52 sets the value of the speed-dependent limit value Vth2 to one of the two values ​​according to whether the absolute value of the changing speed of the target virtual steering angle α2* is less than the threshold value Dth or greater than the threshold value. Here, the speed-dependent limit value Vth2 when it is less than the threshold value Dth is larger than the speed-dependent limit value Vth2 when it is greater than the threshold value Dth.

[0059] This is set in consideration of the fact that the absolute value of the change speed of the virtual steering angle α2 tends to be large when the absolute value of the vehicle speed V is small.

[0060] exist Figure 8A to Figure 8C , the relationship between the change speed of the steering angle α1 of the tractor 20 and the change speed of the virtual steering angle α2 is shown to be dependent on the vehicle speed V. Specifically, Fig. 8A The case where the traction angle β is "-40°" and the steering angle α1 is "-20°" is shown. Figure 8B The case where the traction angle β is "-40°" and the steering angle α1 is "0°" is shown. Figure 8CIndicates the case where the traction angle β is "-40°" and the steering angle α1 is "20°". Figure 8A to Figure 8C The achievable range of the change speed of the steering angle α1 is a range where its magnitude is less than or equal to “ DA1 ”.

[0061] like Figure 8A to Figure 8C As shown, in either case, when the absolute value of the vehicle speed V is small, the range of possible values ​​of the change speed of the virtual steering angle α2 within the range of the change speed of the steering angle α1 that can be achieved by the steering system 60 becomes larger.

[0062] return Figure 6 PU52 obtains the pulling angle β (S58). In addition, PU52 obtains the folding knife pulling angle βth (S60). In this embodiment, the folding knife pulling angle βth is a fixed value determined according to the maximum value of the steering angle α1.

[0063] That is, according to Figure 4 In the model shown, the first-order time differential value of the pull angle β is expressed by the following equation.

[0064] dβ / dt

[0065] =-(V / l2)·sinβ

[0066] -{V / (l1·l2)}·(l2+h1·cosβ)·tanα…(c6)

[0067] Here, when the folding knife phenomenon occurs, when the steering angle α1 is set to the maximum value α1th, the traction angle β cannot be changed. Therefore, the time differential value of the traction angle β in the above-mentioned formula (c6) is set to zero, and the traction angle β when the maximum value α1th is substituted into the steering angle α1 is regarded as the folding knife traction angle βth. However, the steering angle α1 can take both positive and negative values, so both "α1th" and "(-1)·αth" can be substituted into the above-mentioned formula (c6). Therefore, the folding knife traction angle βth actually takes two values. These two folding knife traction angles βth are pre-stored in the storage device 54. Moreover, in the processing of S60, PU52 selects the value of the smaller absolute value of the difference with the traction angle β of the two values ​​according to the sign of the steering angle α1 and the sign of the change speed of the steering angle α1.

[0068] PU52 uses the absolute value of the difference between the folding knife traction angle βth and the traction angle β as input to calculate the traction angle dependent limit value Vth3 (S62). The traction angle dependent limit value Vth3 is a limit value of the vehicle speed V used to suppress the folding knife phenomenon. PU52 sets the traction angle dependent limit value Vth3 when the absolute value of the above difference is smaller to be less than the traction angle dependent limit value Vth3 when the absolute value of the above difference is larger. This processing can also be achieved by PU52 performing a mapping operation on the traction angle dependent limit value Vth3 in a state where mapping data is pre-stored in the storage device 54. Here, the mapping data is data that uses the absolute value of the above difference as an input variable and the traction angle dependent limit value Vth3 as an output variable. In addition, the value of the output variable contained in the mapping data can also be monotonically increased according to the value of the input variable contained in the mapping data.

[0069] Next, if Figure 7 As shown, PU52 obtains the absolute value Δ of the difference between the target virtual steering angle α2* and the virtual steering angle α2 (S70). PU52 uses the target virtual steering angle α2* and the virtual steering angle α2 as inputs to calculate the absolute value Δ of the difference. Next, PU52 determines whether the restriction flag F is "1" (S72). In the case where the vehicle speed V is restricted to the smaller side due to the larger absolute value Δ of the difference, the restriction flag F is "1". In addition, in the case where no restriction is made, the restriction flag F is "0".

[0070] When the PU52 determines that the limit flag F is "0" (S72: No), it determines whether the absolute value of the difference Δ is greater than the threshold value Δth (S74). This process is a process for determining whether the deviation between the control amount and the target value is large in the feedback control with the virtual steering angle α2 as the control amount and the target virtual steering angle α2* as the target value of the control amount. When the PU52 determines that it is greater than the threshold value Δth (S74: Yes), it substitutes "1" into the limit flag F (S76).

[0071] On the other hand, when the PU52 determines that the restriction flag F is "1" (S72: Yes), it determines whether the absolute value Δ of the difference is smaller than the threshold value Δth (S78). When the PU52 determines that it is smaller than the threshold value Δth (S78: Yes), it increments the counter C by "1" (S80). The counter C measures the duration after the state in which the absolute value Δ of the difference is greater than the threshold value Δth is switched to the state less than the threshold value Δth. On the other hand, when the PU52 determines that it is greater than the threshold value Δth (S78: No), it initializes the counter C (S82).

[0072] When the processing of S80 and S82 is completed, PU82 determines whether the counter C is greater than the threshold value Cth (S84). This process is to determine whether the duration after the state where the absolute value Δ of the difference is greater than the threshold value Δth is switched to the state less than the threshold value Δth is greater than a predetermined time. When PU84 determines that it is greater than the threshold value Cth (S84: Yes), "0" is substituted for the limit flag F and the counter C is initialized (S86).

[0073] When the processing of S76 and S86 is completed, or when a negative judgment is made in the processing of S74 and S84, PU52 uses the value of the restriction flag F as input and calculates the deviation-dependent restriction value Vth4 (S8). When the restriction flag F is "0", PU52 substitutes the 0th speed V0 into the deviation-dependent restriction value Vth4. On the other hand, when the restriction flag F is "1", PU52 substitutes the first speed V1 into the deviation-dependent restriction value Vth4. The first speed V1 is smaller than the 0th speed V0. The first speed V1 is a restriction value of the vehicle speed V used to eliminate the state when the virtual steering angle α2 deviates greatly from the target virtual steering angle α2*.

[0074] Then, the PU 52 substitutes the minimum value among the angle-dependent limit value Vth1 , the speed-dependent limit value Vth2 , the traction-angle-dependent limit value Vth3 , and the deviation-dependent limit value Vth4 into the upper limit value Vth ( S90 ).

[0075] In addition, when PU52 completes the processing of S90, Figure 5 Processing of S34.

[0076] "Functions and Effects of the Present Embodiment"

[0077] PU52 sets the upper limit value Vth according to the absolute value of the target virtual steering angle α2*, the absolute value of the change speed of the target virtual steering angle α2*, the absolute value of the difference Δ, and the absolute value of the difference between the traction angle β and the jackknife traction angle βth in the reverse assist control. When the absolute value of the vehicle speed V is small, it is easier to control the virtual steering angle α2 and the traction angle β to approach the desired values ​​than when the absolute value of the vehicle speed V is large. Therefore, according to the present embodiment, the controllability of the reverse assist control can be improved.

[0078] Here, PU52 sets the upper limit value Vth according to the absolute value of the target virtual steering angle α2* and the absolute value of the change speed of the target virtual steering angle α2*. Therefore, the processing executed by PU52 includes a processing of setting the absolute value of the vehicle speed when the rotation radius of the trailer 30 is the first radius to be smaller than the absolute value of the vehicle speed when the rotation radius is the second radius larger than the first radius. Thus, the controllability of the rotation control of the trailer 30 can be improved. That is, when the driver increases the absolute value of the target virtual steering angle α2*, the connected vehicle 10 can be decelerated for the rotation of the trailer 30. In addition, the processing executed by PU52 includes a processing of limiting the absolute value of the vehicle speed to a smaller side when the absolute value of the change speed of the target virtual steering angle α2* is large. Thus, even when the absolute value of the change speed of the target virtual steering angle α2* is large, the virtual steering angle α2 can be suppressed from following the target virtual steering angle.

[0079] In addition, PU52 sets the upper limit value Vth according to the absolute value Δ of the difference. Thus, in the case of control disorder in which the virtual steering angle α2 is set as the control amount due to interference, the connected vehicle 10 can be decelerated to improve controllability. Here, in the case where the absolute value of the vehicle speed is low, the controllability of the feedback control that makes the virtual steering angle α2 close to the target virtual steering angle α2* becomes higher than in the case where the absolute value of the vehicle speed is high. Therefore, in the processing performed by PU52, when the absolute value Δ of the difference between the virtual steering angle α2 and the target virtual steering angle α2* is large, the processing of limiting the absolute value of the vehicle speed to the smaller side is included. Thus, the controllability of the feedback control can be improved.

[0080] In particular, PU52 continues the process of limiting the absolute value of the vehicle speed to be less than the first speed V1 during a predetermined period from the time when the state where the absolute value Δ is greater than the threshold value Δth is changed to the state where the absolute value Δ is less than the threshold value Δth. Thus, it is possible to suppress the occurrence of the following hunting phenomenon, in which the absolute value of the vehicle speed is again limited to be less than the first speed V1 when the state where the absolute value Δ is less than the threshold value Δth is changed again to the state where the absolute value Δ is greater than the threshold value Δth.

[0081] In addition, PU52 sets the upper limit value Vth according to the absolute value of the difference between the towing angle β and the folding knife towing angle βth. Here, if the towing angle β is the folding knife towing angle βth, the steering control of the trailer 30 cannot be performed. Therefore, the processing executed by PU52 includes a processing of limiting the absolute value of the vehicle speed to a smaller value when the absolute value of the difference between the folding knife towing angle βth and the towing angle β is small. Thus, when the absolute value of the difference between the folding knife towing angle βth and the towing angle β is small, the controllability of the control of the towing angle β can be improved. Therefore, the towing angle β can be suppressed from becoming the folding knife towing angle βth. That is, by decelerating the connected vehicle 10 before it becomes uncontrollable, the situation in which the connected vehicle 10 becomes uncontrollable can be prevented before it happens.

[0082] According to the present embodiment described above, the following effects are further achieved.

[0083] (1) The PU 52 executes a process to control the vehicle speed of the connected vehicle 10 to approach the vehicle speed instructed by the driver when the absolute value of the actual vehicle speed of the connected vehicle 10 is equal to or less than the upper limit value Vth. This allows the vehicle speed of the connected vehicle 10 to be controlled to the vehicle speed that satisfies the driver's intention as much as possible.

[0084] (2) PU 52 sets the minimum value among the absolute values ​​of the user-set vehicle speed Vu, the upper limit value Vth, and the default value Vd as the absolute value of the target vehicle speed V*. This allows consideration of factors that cannot be expressed by the upper limit value Vth.

[0085] (3) PU52 controls the virtual steering angle α2 during the reverse control of the vehicle 10. The reverse control of the vehicle 10 is more difficult than the forward control. Therefore, by having PU52 control the virtual steering angle α2 during the reverse control, the controllability of the difficult reverse control can be improved.

[0086] <Other embodiments>

[0087] In addition, the present embodiment can be implemented by being modified as follows. The present embodiment and the following modified examples can be implemented in combination with each other within the range that there is no technical contradiction.

[0088] "Virtual steering angle dependent processing"

[0089] In the process of S52, the angle-dependent limit value Vth1 is selectively set to any one of three or more values ​​according to the absolute value of the target virtual steering angle α2*, but the present invention is not limited thereto. For example, the angle-dependent limit value Vth1 may be set to any one of two values ​​according to whether the absolute value of the target virtual steering angle α2* is greater than or less than a threshold value.

[0090] "About the change speed dependency processing"

[0091] In the processing of S56, the size of the speed-dependent limit value Vth2 is set to one of two values, depending on whether the absolute value of the change speed of the target virtual steering angle α2* is greater than the threshold value Dth, but is not limited to this. For example, the size of the speed-dependent limit value Vth2 may be set to three or more values. In this case, the speed-dependent limit value Vth2 in the case where the absolute value of the change speed of the target virtual steering angle α2* is large is set to be less than the speed-dependent limit value Vth2 in the case where the absolute value of the change speed of the target virtual steering angle α2* is small. This processing may also be achieved, for example, by PU52 performing a mapping operation on the speed-dependent limit value Vth2 in a state where mapping data is stored in the storage device 54. Here, the mapping data is data that uses the absolute value of the change speed of the target virtual steering angle α2* as an input variable and the speed-dependent limit value Vth2 as an output variable.

[0092] "On bias-dependent processing"

[0093] ·exist Figure 7 In the process shown, the deviation-dependent limit value Vth4 is maintained at the first speed V1 until a predetermined time has passed after the state where the absolute value of the difference between the target virtual steering angle α2* and the virtual steering angle α2 is greater than or equal to the threshold value Δth is changed to a state where the absolute value is less than the threshold value Δth, but the present invention is not limited thereto. For example, the 0th speed V0 may be substituted into the deviation-dependent limit value Vth4 at the timing when the state where the absolute value of the difference between the target virtual steering angle α2* and the virtual steering angle α2 is greater than or equal to the threshold value Δth is changed to a state where the absolute value is less than the threshold value Δth.

[0094] ·exist Figure 7 In the processing shown, PU52 sets the deviation-dependent limit value Vth4 to one of two values, depending on whether the absolute value of the difference between the target virtual steering angle α2* and the virtual steering angle α2 is greater than the threshold value Δth, but is not limited to this. For example, the deviation-dependent limit value Vth4 may be set to three or more values. In this case, the deviation-dependent limit value Vth4 when the absolute value of the above difference is larger is set to be less than the deviation-dependent limit value Vth4 when the absolute value of the above difference is smaller. This processing may also be achieved by, for example, PU52 performing a mapping operation on the deviation-dependent limit value Vth4 in a state where mapping data is stored in the storage device 54. Here, the mapping data is data that uses the absolute value of the above difference as an input variable and the deviation-dependent limit value Vth4 as an output variable.

[0095] "About the handling of pull angle dependence"

[0096] In the processing of S58 to S62, the pull angle dependent limit value Vth3 is selectively set to any one of three or more values, but the present invention is not limited thereto. For example, the pull angle dependent limit value Vth3 may be set to any one of two values ​​depending on whether the absolute value of the difference between the folding knife pull angle βth and the pull angle β is greater than or less than a threshold value.

[0097] "About speed limit handling"

[0098] The upper limit value Vth is not necessarily determined by selecting the minimum value among the angle-dependent limit value Vth1, the speed-dependent limit value Vth2, the deviation-dependent limit value Vth4, and the traction-angle-dependent limit value Vth3. For example, a mapping operation may be performed using mapping data that uses variables used when calculating these four values ​​as input variables and uses the upper limit value Vth as an output variable.

[0099] The upper limit value Vth is set to the minimum value among the angle-dependent limit value Vth1, the speed-dependent limit value Vth2, the deviation-dependent limit value Vth4, and the traction-angle-dependent limit value Vth3, but the present invention is not limited thereto. For example, the upper limit value Vth may be set to the minimum of three of the four. Also, for example, the upper limit value Vth may be set to the minimum of two of the four. Also, for example, the upper limit value Vth may be set to the minimum of two of the four. Also, the upper limit value Vth may be set to any one of the above four, such as the angle-dependent limit value Vth1.

[0100] "About virtual steering angle control processing"

[0101] The operation amount of the feedback control using the virtual steering angle α2 as the control amount and the target virtual steering angle α2* as the target value of the control amount is not limited to the steering angle α1 of the front wheels 22 of the tractor 20. For example, as described in the column "Regarding the steering system" below, when the device including the device for steering the front wheels 22 and the device for steering the rear wheels 24 is a steering system, the target value of the yaw rate of the tractor 20 may be used as the operation amount. In this case, the PU 52 may simply set the steering angle of the front wheels 22 and the steering angle of the rear wheels 24 as the operation amount for bringing the yaw rate close to the target value by feedback control.

[0102] About vehicle speed control processing

[0103] For example, in the back-up assist process, the driving speed of the connected vehicle 10 may be controlled by the acceleration operation and the braking operation of the driver. However, in this case, the back-up assist process includes a process of limiting the vehicle speed V to not exceed the upper limit value Vth. In addition, the process of limiting the vehicle speed V to not exceed the default value Vd may also be included.

[0104] About Defaults

[0105] As described in the column "Regarding the steering system" below, when the steering system is different from the above-mentioned embodiment, the default value may be set according to the target steering system. Here, when the steering system includes a plurality of actuators, etc., a limit may be set for the target yaw rate from the viewpoint of the stability margin. This makes it easy to design the absolute value of the vehicle speed for maintaining the stability margin.

[0106] The default value Vd is not necessarily determined based on the response characteristics of the steering system alone. For example, the default value Vd may be set in consideration of the update cycle of the traction angle β, the steering angle α1, and the wheel speeds ωw1 to ωw4. In addition, for example, the default value Vd may be set in consideration of the communication delay time until the control device 50 receives the detection values ​​of the traction angle β, the steering angle α1, and the wheel speeds ωw1 to ωw4.

[0107] About Steering Control System

[0108] The steering system connected to the vehicle 10 is not limited to a device for steering the front wheels 22. For example, a device may be provided with a device for steering the front wheels 22 and a device for steering the rear wheels 24. In addition, for example, a device may be provided with an in-wheel motor.

[0109] About the Control Device

[0110] ·The control device is not limited to a device having PU52 and storage device 54 and executing software processing. For example, it may also be provided with a dedicated hardware circuit such as ASIC that performs hardware processing on at least a part of the processing executed in the above-mentioned embodiment. That is, the control device only needs to be any one of the following structures (a) to (c). (a) A processing circuit comprising a processing device that executes all the above-mentioned processing according to a program and a program storage device such as a storage device that stores the program. (b) A processing circuit comprising a processing device and a program storage device that execute a part of the above-mentioned processing according to a program, and a dedicated hardware circuit that executes the remaining processing. (c) A processing circuit comprising a dedicated hardware circuit that executes all the above-mentioned processing. Here, there may be multiple software execution devices and dedicated hardware circuits having a processing device and a program storage device.

[0111] About Computer

[0112] The computer that executes the control program such as the back-up assist program 54a is not limited to the computer mounted on the connected vehicle 10. For example, the computer may be constituted by both the PU 52 mounted on the connected vehicle 10 and the driver's mobile terminal. In this case, for example, the processing of S34 may be executed by the mobile terminal.

[0113] "About Vehicles"

[0114] ·As a connected vehicle, not limited to Figure 1 The vehicle illustrated in FIG.

[0115] In addition, in this specification, in the "processing of limiting the size of B to the smaller side according to A while satisfying the condition that B in the case of A being larger is less than B in the case of A being smaller", the case of A being larger and the case of A being smaller refer to the relative size relationship when the two are compared. For example, "the case of A being larger" corresponds to the case of "A being a first value", and "the case of A being smaller" corresponds to "the case of A being a second value smaller than the first value". And according to the above processing, based on the setting of the first value and the second value, it means that B in the case of A being the first value is smaller than B in the case of A being the second value.

Claims

1. A control device for a coupled vehicle, the coupled vehicle comprising a tractor and a trailer towed by the tractor, wherein: The connected vehicle has an interface for the driver to indicate a target virtual steering angle. The target virtual steering angle is a target value of the virtual steering angle. The virtual steering angle is a variable indicating the travel direction of the connection portion between the trailer and the tractor. The control device is configured to execute a target virtual steering angle acquisition process, a virtual steering angle control process, and a vehicle speed limit process. The target virtual steering angle acquisition process is a process of acquiring the target virtual steering angle. The virtual steering angle control process includes a process of operating a steering system of the connected vehicle in order to control the virtual steering angle to the target virtual steering angle. The vehicle speed limit processing is a processing for limiting the absolute value of the vehicle speed of the connected vehicle to a smaller side during the execution of the virtual steering angle control processing, and includes a virtual steering angle dependent processing that takes the target virtual steering angle as input and limits the absolute value of the vehicle speed to a smaller side.

2. The vehicle-connected control device according to claim 1, wherein: The target virtual steering angle represents the angle between the traveling direction and the forward direction of the trailer. The virtual steering angle dependent processing includes the following change speed dependent processing, which limits the absolute value of the vehicle speed to a smaller side according to the target virtual steering angle so as to satisfy the condition that the absolute value of the vehicle speed when the absolute value of the angle formed by the traveling direction relative to the forward direction is larger is set to be lower than the absolute value of the vehicle speed when the absolute value of the angle formed is smaller.

3. The vehicle-connected control device according to claim 1, wherein: The vehicle speed limit processing includes the following change speed dependent processing, which satisfies the condition that the absolute value of the vehicle speed when the absolute value of the change speed of the target virtual steering angle is larger is set to be less than the absolute value of the vehicle speed when the absolute value of the change speed is smaller, while limiting the absolute value of the vehicle speed to the smaller side according to the absolute value of the change speed.

4. The vehicle-connected control device according to claim 1, wherein: is configured to execute a virtual steering angle acquisition process, The virtual steering angle acquisition process is a process of acquiring the virtual steering angle. The virtual steering angle control process includes feedback processing, The feedback processing is processing for bringing the virtual steering angle close to the target virtual steering angle through feedback control. The vehicle speed limit processing includes the following deviation-dependent processing, which satisfies the condition that the absolute value of the vehicle speed when the absolute value of the difference between the virtual steering angle and the target virtual steering angle is larger is set to be less than the absolute value of the vehicle speed when the absolute value of the difference is smaller, and limits the absolute value of the vehicle speed to the smaller side according to the absolute value of the difference.

5. The vehicle-connected control device according to claim 4, wherein: The deviation dependency processing includes the following processing: limiting the absolute value of the vehicle speed when the absolute value of the difference between the virtual steering angle and the target virtual steering angle is greater than a threshold value to a first speed or less than a maximum value of the absolute value of the vehicle speed that can be taken when the absolute value of the difference is less than the threshold value; as well as The absolute value of the vehicle speed is limited to be equal to or lower than the first speed during a predetermined period from the time when the absolute value of the difference changes from a state equal to or higher than the threshold value to a state equal to or lower than the threshold value.

6. The vehicle-connected control device according to claim 1, wherein: is configured to execute a hitch angle acquisition process for acquiring a hitch angle, The towing angle is the angle between the front and rear directions of the tractor and the front and rear directions of the trailer. The vehicle speed limiting process includes the following hitch angle dependency process, limiting the absolute value of the vehicle speed according to the hitch angle while satisfying the condition that the absolute value of the vehicle speed when the absolute value of the difference between the hitch angle and the folding knife hitch angle is smaller is set to be less than the absolute value of the vehicle speed when the absolute value of the difference between the hitch angle and the folding knife hitch angle is larger, The folding knife pulling angle is the pulling angle generated by the folding knife.

7. The vehicle-connected control device according to claim 1, wherein: is configured to execute vehicle speed control processing, The vehicle speed control process is a process of operating the driving system of the tractor vehicle in order to control the vehicle speed. The vehicle speed limiting process is a process of limiting the absolute value of the vehicle speed controlled by the vehicle speed control process to a smaller side.

8. The vehicle-connected control device according to claim 7, wherein: is constituted to perform acceptance processing, The receiving process is a process of receiving the driver's instruction on the absolute value of the vehicle speed. The vehicle speed limit process is a process of calculating an upper limit value of the absolute value of the vehicle speed. The vehicle speed control process includes a process of controlling such that the absolute value of the actual vehicle speed approaches the absolute value of the vehicle speed instructed by the driver, under the condition that the absolute value of the actual vehicle speed of the connected vehicle is equal to or less than the upper limit value.

9. The vehicle-connected control device according to claim 8, wherein: The vehicle speed control process includes a target vehicle speed setting process and an operation process. The target vehicle speed setting process is a process of setting the minimum value among the absolute value of the instructed vehicle speed, the upper limit value, and the absolute value of the default vehicle speed as the absolute value of the target vehicle speed. The operation process is a process of operating the drive system of the connected vehicle so that the absolute value of the vehicle speed approaches the absolute value of the target vehicle speed.

10. The vehicle-connected control device according to claim 1, wherein: The virtual steering angle control process is configured to be executed during reverse control of the coupled vehicle.

11. A method for controlling a coupled vehicle, the coupled vehicle comprising a tractor and a trailer towed by the tractor, wherein: The connected vehicle has an interface for the driver to indicate a target virtual steering angle. The target virtual steering angle is a target value of the virtual steering angle. The virtual steering angle is a variable indicating the travel direction of the connection portion between the trailer and the tractor. The control method includes the steps of executing a target virtual steering angle acquisition process, a virtual steering angle control process, and a vehicle speed limit process. The target virtual steering angle acquisition process is a process of acquiring the target virtual steering angle. The virtual steering angle control process includes a process of operating a steering system of the connected vehicle in order to control the virtual steering angle to the target virtual steering angle. The vehicle speed limit processing is a processing for limiting the absolute value of the vehicle speed of the connected vehicle to a smaller side during the execution of the virtual steering angle control processing, and includes a virtual steering angle dependent processing that takes the target virtual steering angle as input and limits the absolute value of the vehicle speed to a smaller side.

12. A control program for a coupled vehicle, the coupled vehicle comprising a tractor and a trailer towed by the tractor, wherein: The connected vehicle has an interface for the driver to indicate a target virtual steering angle. The target virtual steering angle is a target value of the virtual steering angle. The virtual steering angle is a variable indicating the travel direction of the connection portion between the trailer and the tractor. The control program includes instructions for causing the computer to execute a target virtual steering angle acquisition process, a virtual steering angle control process, and a vehicle speed limit process. The target virtual steering angle acquisition process is a process of acquiring the target virtual steering angle. The virtual steering angle control process includes a process of operating a steering system of the connected vehicle in order to control the virtual steering angle to the target virtual steering angle. The vehicle speed limit processing is a processing for limiting the absolute value of the vehicle speed of the connected vehicle to a smaller side during the execution of the virtual steering angle control processing, and includes a virtual steering angle dependent processing that takes the target virtual steering angle as input and limits the absolute value of the vehicle speed to a smaller side.

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