Controller of articulated vehicle, control method of articulated vehicle, and control program of articulated vehicle

Abstract

To provide a controller of an articulated vehicle making it possible to express an intention of steering a trailer without the necessity of including new input means.SOLUTION: When a backing assist mode is off, a PU 92 regards an input manipulation performed on a steering wheel 50 as an instruction of steering a tractor. When the backing assist mode is on, the PU 92 regards the input manipulation performed on the steering wheel 50 as an instruction of steering a trailer.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] Conventionally, there exists a combination vehicle in which a trailer is coupled to a tractor. Patent Document 1 proposes a control device that assists in driving the combination vehicle in reverse. This control device operates the steered wheels to control the traveling of the trailer in response to the driver's operation of a knob. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Patent No. 10,144,452 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above case, a means for inputting an intention to steer the trailer by the driver is required, separate from the means for inputting an intention to steer the tractor. [Means for solving the problem]

[0005] Means for solving the above problems and their effects will be described below. 1. A control device for an articulated vehicle that is applied to an articulated vehicle that includes a tractor and a trailer towed by the tractor, the tractor having an input unit and steered wheels, and is configured to execute a switching determination process, a tractor steering process, and a trailer steering process, the switching determination process being a process that determines whether the reverse assist mode is on or the reverse assist mode is off, the tractor steering process being a process that steers the tractor in response to an input operation to the input unit when the reverse assist mode is off, and the trailer steering process being a process that manipulates the steering angle of the steered wheels to steer the trailer in response to an input operation to the input unit when the reverse assist mode is on, with power transmission between the input unit and the steered wheels being cut off.

[0006] In the above configuration, when the reverse assist mode is OFF, the steered wheels of the tractor can be steered by the input unit. On the other hand, when the reverse assist mode is ON, the input unit can be used to instruct steering of the trailer. Therefore, an intention to steer the trailer can be expressed without providing a new input means.

[0007] 2. A control device for combined vehicles as described in claim 1 above, configured to execute a matching process, the matching process including, when the reverse assist mode is switched from an off state to an on state, a process of changing the state of the input unit so as to match the state of the trailer when the combined vehicles are traveling.

[0008] In the above configuration, when the reverse assist mode is switched to the on state, the state of the input unit is displaced to match the state of the trailer. This makes it possible to match the state of the input unit to the state of the trailer without displacing the steered wheels when the reverse assist mode is switched to the on state.

[0009] 3. The control device for articulated vehicles as set forth in claim 2, wherein the matching process includes a process for displacing the input unit to a position matching a state corresponding to a boundary of the allowable range when the state of the trailer falls outside the allowable range.

[0010] In the above-described configuration, the input unit is changed to a position where the state of the trailer matches a state corresponding to the boundary of the tolerance range, thereby allowing the driver to properly grasp the state related to steering of the trailer.

[0011] 4. A control device for articulated vehicles as set forth in any one of 1 to 3 above, configured to execute a deviation notification process, the deviation notification process including a process for notifying the vehicle when a state of the trailer deviates from an acceptable range while the trailer steering process is being executed.

[0012] In the above configuration, when the driver is inputting an intention to steer the trailer and issues a steering instruction that cannot actually be realized, the driver can be notified of this. 5. A control device for an articulated vehicle as described in 1 above, which is configured to execute a reaction force imparting process, the reaction force imparting process being a process for imparting a reaction force against the operation of the input unit in accordance with the operation state of the input unit when the reverse assist mode is on, and including a process for making the reaction force when the steering state has a small turning radius of the trailer equal to or greater than the reaction force when the steering state has a large turning radius of the trailer.

[0013] In the above configuration, the reaction force when the trailer is steered to have a small turning radius is set to be equal to or greater than the reaction force when the trailer is steered to have a large turning radius, thereby providing the driver with a steering feel similar to that of a normal vehicle when steering the trailer.

[0014] 6. A control device for articulated vehicles as described in 5 above, wherein the reaction force application process includes a process for increasing the amount of increase in the reaction force relative to a unit amount of displacement of the input section as the state of the trailer approaches the boundary of the allowable range.

[0015] With the above configuration, it is possible to prevent the state of the input unit from becoming a state that corresponds to a state that exceeds the tolerable range of the trailer. 7. A control device for an articulated vehicle as described in any one of 1 to 6 above, configured to execute a matching process, the matching process including a process of changing the state of the input unit so as to match the steering angle of the steered wheels when the reverse assist mode is switched from an on state to an off state of the reverse assist mode.

[0016] In the above configuration, when the reverse assist mode is switched to the OFF state, the state of the input unit is changed to match the state of the steered wheels of the tractor. This makes it possible to match the state of the input unit to the state of the steered wheels without displacing the steered wheels when the reverse assist mode is switched to the OFF state.

[0017] 8. A control device for articulated vehicles as described in 2, 3 or 7 above, which is configured to execute a reduction process, the reduction process including a process of reducing the displacement speed of the input unit when the driver touches the input unit while the matching process is being executed.

[0018] In the above configuration, when the driver touches the input unit during execution of a matching process associated with switching from one of the two states, the ON state or the OFF state, of the reverse assist mode to the other, the displacement speed of the input unit is reduced, thereby making it possible to prevent the driver from feeling that the vehicle is behaving in a manner that is largely contrary to his or her will.

[0019] 9. A control device for articulated vehicles as set forth in any one of 2, 3, 7 and 8 above, configured to execute a switching notification process, the switching notification process including a process of notifying the input unit prior to the displacement of the input unit due to the matching process.

[0020] In the above configuration, since the switching notification process is executed, it is easy for the driver to understand that what can be instructed by the input operation of the input unit has been switched. 10. A control device for an articulated vehicle as set forth in any one of 1 to 9 above, wherein the trailer steering process includes a target virtual steering angle setting process and a virtual steering angle control process, the target virtual steering angle setting process is a process for setting a target virtual steering angle in response to an input operation on the input section, the target virtual steering angle is a target value of the virtual steering angle, the virtual steering angle is a variable indicating the traveling direction of the connection point between the trailer and the tractor, and the virtual steering angle control process is a process for manipulating the steering angle of the steered wheels using a control operation amount that sets the virtual steering angle as a control amount and the target virtual steering angle as a target value of the control amount.

[0021] In the above configuration, an instruction regarding the traveling direction of the connection point between the trailer and the tractor can be given by operating the input unit. 11. The control device for articulated vehicles according to any one of 1 to 10 above, wherein the input section is a steering wheel.

[0022] The above arrangement allows the driver to steer the trailer using the means most commonly used for driving a vehicle. 12. A method for controlling an articulated vehicle, comprising the steps of executing each of the processes in the control device for an articulated vehicle as recited in any one of 1 to 11 above.

[0023] 13. A control program for an articulated vehicle that causes a computer to execute each of the processes in the control device for an articulated vehicle described in any one of 1 to 11 above. [Brief description of the drawings]

[0024] [Figure 1] 1 is a perspective view showing a configuration of an articulated vehicle according to one embodiment. FIG. [Diagram 2] FIG. 2 is a block diagram showing a configuration of a control system according to the embodiment. [Diagram 3] 4 is a flowchart showing a procedure of a process executed by a control device according to the embodiment. [Figure 4] FIG. 2 is a diagram showing a model of an articulated vehicle according to the embodiment. [Diagram 5]4 is a flowchart showing a procedure of a process executed by a control device according to the embodiment. [Figure 6] 4 is a flowchart showing a procedure of a process executed by a control device according to the embodiment. [Figure 7] 4 is a flowchart showing a procedure of a process executed by a control device according to the embodiment. [Figure 8] 6(a) to 6(c) are diagrams showing the operation according to the embodiment. [Figure 9] 6(a) to 6(d) are diagrams illustrating the operation according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Hereinafter, an embodiment will be described with reference to the drawings. "Configuration of articulated vehicles" As shown in Fig. 1, the articulated 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. Fig. 1 also illustrates a box-shaped trailer as the trailer 30. The trailer 30 has wheels 32. The wheels 32 include two wheels, a right wheel and a left wheel.

[0026] The trailer 30 is connected to the rear 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 rotatably about an axis 42. The axis 42 extends along the height direction of the tractor 20.

[0027] FIG. 2 shows some of the members provided on the tractor 20. 2, a reaction force is applied to a steering wheel 50 in a steering system provided in the tractor 20 by a reaction force motor 52. The reaction force is a torque with an opposite sign to the torque applied by the driver to the steering wheel 50. The output voltage of an inverter 54 is applied to the terminals of the reaction force motor 52.

[0028] On the other hand, the power of a steering motor 62 is applied to the front wheels 22 as steered wheels provided in the steering system via a rack and pinion mechanism 60. The output voltage of an inverter 64 is applied to the terminals of the steering motor 62.

[0029] The steering control device 70 controls the torque of the reaction force motor 52 to control the control amount of the steering wheel 50 as the control object. Here, the control amount is the reaction force. The steering control device 70 also controls the torque of the steering motor 62 to control the control amount of the front wheels 22 as the control object. Here, the control amount is the steering angle. The steering angle is the turning angle of the tires of the front wheels 22.

[0030] To control the control amount, steering control device 70 refers to steering torque Th, which is the torque input to steering wheel 50, detected by torque sensor 72. To control the control amount, steering control device 70 also refers to steering angle θh detected by steering angle sensor 74. To control the control amount, steering control device 70 also refers to rotation angle θm of steering motor 62 detected by rotation angle sensor 76.

[0031] The tractor 20 includes a drive system 80. The drive system 80 includes at least one of an internal combustion engine and a rotating electric machine as a thrust generating device of the vehicle. The tractor 20 includes a braking system 82. The braking system 82 includes at least one of a device that slows down the rotation of the wheels by frictional force and a device that slows down the rotation of the wheels by converting the power of the wheels into electrical energy. Note that the device that slows down the rotation of the wheels by converting into electrical energy may be shared with the rotating electric machine of the drive system.

[0032] The tractor 20 is equipped with an ADASECU 90. The ADASECU 90 operates the steering system, the drive system 80, and the braking system 82 to control the control amount of the combined vehicle 10 as the control object. The control amount is the vehicle speed, the driving direction, the hitch angle, and the like. The hitch angle is the angle between the front-rear direction of the tractor 20 and the front-rear direction of the trailer 30. The drive system 80 may include a drive control device that controls the internal combustion engine and the rotating electric machine. In this case, "the ADASECU 90 operates the drive system 80" means that the ADASECU 90 outputs a command signal to the drive control device. Also, the braking system 82 may include a brake control device that controls a device that decelerates the rotation of the wheels. In this case, "the ADASECU 90 operates the brake system 82" means that the ADASECU 90 outputs a command signal to the brake control device. Also, "the ADASECU 90 operates the steering control device 70" means that the ADASECU 90 outputs a command signal to the steering control device 70.

[0033] The ADASECU90 refers to the hitch angle β detected by the hitch angle sensor 100 to control the control amount. The hitch angle β can be either positive or negative depending on the angle between the direction in which the tractor 20 moves from the rear to the front and the direction in which the trailer 30 moves from the rear to the front. For example, the sign of the hitch angle β may be positive when the direction in which the trailer 30 moves from the rear to the front is shifted counterclockwise by less than 180° from the direction in which the tractor 20 moves from the rear to the front. The ADASECU90 also refers to the wheel speeds ωw1 to ωw4 detected by the wheel speed sensor 102. The wheel speeds ωw1 and ωw2 are the rotation speeds of the right front wheel 22 and the left front wheel 22, respectively. The wheel speeds ωw3 and ωw4 are the rotation speeds of the right rear wheel 24 and the left rear wheel 24, respectively.

[0034] The ADASECU90 sets the control of the control amount according to the operation state of the user interface 104. The user interface 104 is for transmitting the user's intention to the ADASECU90, such as selecting one of the two driving modes, automatic driving and manual driving.

[0035] The ADASECU 90 includes a PU 92 and a storage device 94. The PU 92 is a software processing device including at least one of a CPU, a GPU, a TPU, and the like. A reverse assist program 94a is stored in the storage device 94. The reverse assist program 94a is a program that prescribes commands for causing the PU 92 to execute reverse assist processing. The reverse assist processing is processing that automatically performs steering processing of the steered wheels when the combination vehicle 10 is traveling in reverse. The reverse assist program 94a is a program for reducing the burden of reverse driving on the driver.

[0036] That is, when the combination vehicle 10 is traveling in reverse, even if the steering angle of the tractor 20 is the same, the behavior of the trailer 30 changes depending on the hitch angle β. Therefore, high driving skills are required for reverse control. The reverse assist process by the reverse assist program 94a is a process that assists the driver by controlling the steering angle of the tractor 20. However, the reverse assist process leaves instructions for steering the trailer 30 to the driver. Here, instructions for steering the trailer 30 are given by the steering wheel 50. That is, when the reverse assist mode that executes the reverse assist process is in the ON state, the steering wheel 50 serves as a means for inputting instructions for steering the trailer 30. On the other hand, when the reverse assist mode is in the OFF state, the steering wheel 50 serves as a means for inputting instructions for steering the tractor 20.

[0037] "Switching to reverse assist mode" Fig. 3 shows the procedure for switching the reverse assist mode from OFF to ON. The process shown in Fig. 3 is realized by the PU 92 repeatedly executing the reverse assist program 94a, for example, at a predetermined interval. In the following, the step number of each process is represented by a number preceded by "S".

[0038] In the series of processes shown in Fig. 3, the PU 92 first obtains the steering angle α1 of the tractor 20 (S10). The steering angle α1 is calculated each time by the steering control device 70 using the rotation angle θm as an input. The PU 92 obtains the steering angle α1 calculated each time by the steering control device 70. The PU 92 also obtains the hitch angle β (S12). The PU 92 then calculates a virtual steering angle α2 based on the steering angle α1 and the hitch angle β (S14). In this embodiment, as an example, the virtual steering angle α2 is defined by the angle between the forward and backward directions of the trailer 30 and the traveling direction of the ball joint 40.

[0039] Here, the reason for calculating the virtual steering angle α2 from the turning angle α1 and the hitch angle β will be described with reference to FIG. FIG. 4 shows a model of the articulated vehicle 10 used in this embodiment. In the model shown in FIG. 4, the pair of front wheels 22 of the tractor 20 are the front wheels C0, and the pair of rear wheels 24 of the tractor 20 are the rear wheels B1. That is, a two-wheel model is adopted for the tractor 20. The pair of wheels 32 of the trailer 30 are the wheels B2. The angle between the line determined by the front wheels C0 and the hitch point C1 and the line determined by the hitch point C1 and the wheels B2 is the hitch angle β. The hitch point C1 corresponds to the shaft 42 in FIG. 1. The front wheel speed VC0, which is the speed of the front wheels C0, is a vector moving in the direction of the steering angle α1. The steering angle α1 is quantified as the angle between the direction of the front wheels C0 and the line determined by the front wheels C0 and the hitch point C1. The direction of the vehicle speed V is parallel to the line determined by the front wheels C0 and the hitch point C1. The angle between the direction of vehicle speed V and the x direction in Fig. 4 is θ1. Distance l1 is the length between the front wheel C0 and the rear wheel B1. Distance h1 is the length between the rear wheel B1 and the hitch point C1.

[0040] According to the above definition, the direction of the speed VC1 of the hitch point C1 relative to the direction from the wheel B2 to the hitch point C1 is the virtual steering angle α2. If the angle γ1 between the direction of the speed VC1 of the hitch point C1 relative to the direction from the hitch point C1 to the front wheel C0 is used, the virtual steering angle α2 is "-(β-γ1)".

[0041] In the model shown in FIG. 4, the following equations (c1) to (c3) are established using 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 hitch point C1.

[0042] VC0 cosα1 = VB1 …(c1) xc0 = xb1 + l1 cosθ1 … (c2) xc1 = xb1 - h1 cosθ1 … (c3) By differentiating both sides of the above equations (c2) and (c3) and using equation (c1), we obtain the following equation (c4).

[0043] h1·tanα1+l1·tanγ1=0 …(c4) According to the above 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).

[0044] α2=-β-arctan{(h1 / l1)·tan(α1)} …(c5) That is, the virtual steering angle α2 can be calculated from the hitch angle β and the steering angle α1. In the process of S14, it is not essential to calculate the virtual steering angle α2 using the above formula (c5). For example, by storing map data in the storage device 94, the PU 92 may perform map calculations to calculate the virtual steering angle α2 in the process of S14. The map data uses the hitch angle β and the steering angle α1 as input variables and uses the virtual steering angle α2 as an output variable.

[0045] Here, map data refers to a set of data consisting of discrete values ​​of input variables and values ​​of output variables corresponding to each of the input variable values. Furthermore, the map calculation may be a process in which, when the value of an input variable matches any of the values ​​of the input variables in the map data, the value of the output variable in the corresponding map data is used as the calculation result. Furthermore, the map calculation may be a process in which, when the value of an input variable does not match any of the values ​​of the input variables in the map data, the value obtained by interpolating the values ​​of multiple output variables included in the map data is used as the calculation result. Alternatively, the map calculation may be a process in which, when the value of an input variable does not match any of the values ​​of the input variables in the map data, the value of the output variable in the map data that corresponds to the closest value among the values ​​of multiple input variables included in the map data is used as the calculation result.

[0046] Next, the PU 92 calculates the maximum virtual steering angle α2th (S16). The maximum virtual steering angle α2th is the lower limit of the magnitude of the virtual steering angle α2 when the jackknife phenomenon occurs. That is, according to the model shown in FIG. 4, the first-order time differential value of the hitch angle β is expressed by the following equation.

[0047] dβ / dt =-(V / l2)·sinβ -{V / (l1·l2)}·(l2+h1·cosβ)·tanα …(c6) Here, when the jackknife phenomenon occurs, even if the steering angle α1 is set to the maximum value α1th, the hitch angle β cannot be changed. Therefore, the hitch angle β obtained when the time differential value of the hitch angle β in the above formula (c6) is set to zero and the maximum value α1th is substituted for the steering angle α1 is regarded as the jackknife hitch angle βth. However, since the steering angle α1 can take both positive and negative values, both "α1th" and "(-1)·α1th" can be substituted for the above formula (c6). Therefore, the jackknife hitch angle βth actually takes two values. These two jackknife hitch angles βth are stored in the storage device 94 in advance. The PU 92 then substitutes, for the jackknife hitch angle βth, the value of the two values ​​that has the smaller absolute value of the difference from the hitch angle β. Then, in the above formula (c5), the PU92 substitutes the jackknife hitch angle βth for the hitch angle β and substitutes "α1th" or "(-1)·α1th" for the steering angle α1. Here, the sign of the steering angle α1 is made to match the sign of the actual steering angle α1. The virtual steering angle α2 calculated in this way is the maximum virtual steering angle α2th.

[0048] Next, the PU 92 judges whether or not the transient flag F1 is "1" (S18). When the transient flag F1 is "1", it indicates that a transient process is being performed after the reverse assist mode is switched from the OFF state to the ON state. When the transient flag F1 is "0", it indicates that the above-mentioned transient process is not being performed. When the PU 92 judges that the transient flag F1 is "0" (S18: NO), it judges whether or not the reverse assist mode has been switched from the OFF state to the ON state (S20). When the PU 92 judges that the mode has been switched (S20: YES), it vibrates the steering wheel 50 (S22). This process is for notifying the driver that the steering wheel 50 has been switched from a means for instructing steering of the tractor 20 to a means for instructing steering of the trailer 30. In the process of S22, the PU 92 assigns "1" to the transient flag F1.

[0049] Next, the PU 92 judges whether the magnitude of the virtual steering angle α2 is equal to or smaller than the maximum virtual steering angle α2th (S24). If the PU 92 judges that the magnitude of the virtual steering angle α2 is equal to or smaller than the maximum virtual steering angle α2th (S24: YES), the PU 92 controls the steering angle θh so that it coincides with a value corresponding to the virtual steering angle α2 (S26). On the other hand, if the PU 92 judges that the magnitude of the virtual steering angle α2 is larger than the maximum virtual steering angle α2th (S24: NO), the PU 92 controls the steering angle θh so that it coincides with a value corresponding to the maximum virtual steering angle α2th (S28). At this time, the PU 92 vibrates the steering wheel 50 when the steering angle θh coincides with the maximum virtual steering angle α2th.

[0050] On the other hand, when the PU92 determines that the transient flag F1 is "1" (S18: YES), the PU92 determines whether or not the steering angle θh matches the virtual steering angle α2 (maximum virtual steering angle α2th) (S30). In more detail, when the process of S26 is being executed, the PU92 determines whether or not the steering angle θh matches the virtual steering angle α2. On the other hand, when the process of S28 is being executed, the PU92 determines whether or not the steering angle θh matches the maximum virtual steering angle α2th. The process of S30 is a process for determining whether or not the processes of S26 and S28 have been completed.

[0051] When it is determined that there is no match (S30: NO), the PU 92 determines whether the magnitude of the steering torque Th is equal to or greater than the threshold value Tth (S32). This process is a process for determining whether the driver has touched the steering wheel 50. That is, the driver switches the reverse assist mode from the OFF state to the ON state by operating the user interface 104. Therefore, the driver does not touch the steering wheel 50 immediately after the reverse assist mode is switched from the OFF state to the ON state. Although the processes of S26 and S28 are intended to be executed before the driver touches the steering wheel 50, there is a possibility that the driver may actually touch the steering wheel 50 while the processes of S26 and S28 are being executed.

[0052] When it is determined that the steering angular velocity ωh is equal to or greater than the threshold value Tth (S32: YES), the PU 92 reduces the magnitude of the steering angular velocity ωh (S34). On the other hand, if the PU 92 determines that they match (S30: YES), it assigns "0" to the transient flag F1 (S36: YES).

[0053] The PU 92 temporarily ends the series of processes shown in FIG. 3 when it completes the processes of S26, S28, S34, and S36, or when a negative determination is made in the processes of S20 and S32.

[0054] "Processing during reverse assist mode" The process in the reverse assist mode will be described with reference to Fig. 5. The process shown in Fig. 5 is realized by the PU 92 repeatedly executing the reverse assist program 94a, for example, at a predetermined interval.

[0055] In the series of processes shown in FIG. 5, the PU 92 first judges whether or not the logical product of the following condition (A) and condition (B) is true (S40). Condition (A): The reverse assist mode is on.

[0056] Condition (B): The transient flag F1 is "0". When the PU 92 determines that the logical product is true (S40: YES), it executes the same processes as those in S10 to S16 (S42 to S48).

[0057] Next, the PU 92 calculates a reaction force to be applied to the steering wheel 50 using the virtual steering angle α2 as an input (S50). The PU 92 sets the magnitude of the reaction force when the virtual steering angle α2 is large to be equal to or greater than the magnitude of the reaction force when the virtual steering angle α2 is small. In particular, the PU 92 sets the increase in the reaction force with respect to a unit amount increase in the magnitude of the virtual steering angle α2 to be greater when the magnitude of the virtual steering angle α2 is equal to or greater than the maximum virtual steering angle α2th than when it is less than the maximum virtual steering angle α2th. This setting is for suppressing the magnitude of the steering angle θh from being further displaced beyond the maximum virtual steering angle α2th.

[0058] The process of S50 may be, for example, a process of performing map calculation of the reaction force by the PU 92 in a state where map data is stored in the storage device 94. Here, the map data is data in which the virtual steering angle α2 is an input variable and the reaction force is an output variable.

[0059] Next, the PU 92 judges whether the magnitude of the virtual steering angle α2 is larger than the maximum virtual steering angle α2th (S52). If the PU 92 judges that the virtual steering angle α2 is larger than the maximum virtual steering angle α2th (S52: YES), the PU 92 superimposes a component that vibrates the steering wheel 50 on the reaction force (S54). This process is for notifying the driver that the turning radius of the trailer 30 cannot be made smaller than this.

[0060] Then, the PU 52 operates the reaction force motor 52 in accordance with the reaction force calculated by the process of S50 (S56). At this time, the PU 52 superimposes a vibration component on the torque of the reaction force motor 52 if the process of S54 has been performed.

[0061] When the process of S56 is completed or when a negative determination is made in the process of S40, the PU 92 temporarily ends the series of processes shown in FIG. "Switching to reverse assist mode off" A process for switching the reverse assist mode from the ON state to the OFF state is shown in Fig. 6. The process shown in Fig. 6 is realized by the PU 92 repeatedly executing the reverse assist program 94a, for example, at a predetermined interval.

[0062] In the series of processes shown in FIG. 6, the PU 92 first executes the same processes as those in S10 to S16 (S60 to S66). Next, the PU 92 determines whether or not the transient flag F2 is "1" (S68). When the transient flag F2 is "1", this indicates that a transient process is being performed after the reverse assist mode has switched from an ON state to an OFF state. When the transient flag F2 is "0", this indicates that the above-mentioned transient process is not being performed. When the PU 92 determines that the transient flag F2 is "0" (S68: NO), it determines whether or not the reverse assist mode has switched from an ON state to an OFF state (S70).

[0063] When it is determined that the steering wheel 50 has been switched (S70: YES), the PU 92 vibrates the steering wheel 50 (S72). This process is for notifying the driver that the steering wheel 50 has been switched from a means for instructing steering of the trailer 30 to a means for instructing steering of the tractor 20. In addition, in the process of S72, the PU 92 assigns "1" to the transient flag F2. Next, the PU 92 operates the reaction force motor 52 to displace the steering wheel 50 so that the steering angle θh coincides with a value corresponding to the steering angle α1 (S74).

[0064] On the other hand, when it is determined that the transient flag F2 is "1" (S68: YES), it is determined whether or not the steering angle θh coincides with the turning angle α1 (S76). When it is determined that they do not coincide (S76: NO), the PU 92 determines whether or not the magnitude of the steering torque Th is equal to or greater than the threshold value Tth (S78). This process is a process for determining whether or not the driver has touched the steering wheel 50. That is, the reverse assist mode is switched from the ON state to the OFF state by the driver operating the user interface 104. Therefore, the driver does not touch the steering wheel 50 immediately after the reverse assist mode is switched from the OFF state to the ON state. Although the process of S74 is intended to be executed before the driver touches the steering wheel 50, in reality, there is a possibility that the driver will touch the steering wheel 50 while the process of S74 is being executed.

[0065] When it is determined that the steering angular velocity ωh is equal to or greater than the threshold value Tth (S78: YES), the PU 92 reduces the magnitude of the steering angular velocity ωh (S80). On the other hand, if the PU 92 determines that they match (S76: YES), it assigns "0" to the transient flag F2 (S82: YES).

[0066] When the PU 92 completes the processes of S74, S80, and S82, or when a negative determination is made in the processes of S70 and S78, the PU 92 temporarily ends the series of processes shown in FIG. "Steering processing" The steering process will be described with reference to Fig. 7. The series of processes shown in Fig. 7 is realized by the PU 92 repeatedly executing the reverse assist program 94a, for example, at a predetermined interval.

[0067] In the series of processes shown in FIG. 7, the PU 92 first determines whether or not the logical product of the above-mentioned condition (A) and condition (B) is true (S90). When the logical product is determined to be true (S90: YES), the PU 92 acquires the steering angle θh (S92). Then, the PU 92 substitutes a value obtained by performing a predetermined conversion on the steering angle θh for the target virtual steering angle α2* (S94). Next, the PU 92 calculates the target steering angle α1*, which is the manipulated variable of the feedback control in which the virtual steering angle α2 is used as the controlled variable and the target virtual steering angle α2* is used as the target value of the controlled variable (S96). Then, the PU 92 operates the steering motor 62 so that the steering angle α1 becomes the target steering angle α1* (S98).

[0068] On the other hand, when the PU 92 determines that the above logical product is false (S90: NO), it determines whether or not the logical product of the following conditions (C) and (D) is true (S100). Condition (C): The reverse assist mode is in the OFF state.

[0069] Condition (D): The transient flag F2 is "0". When the PU 92 determines that the logical product of the condition (C) and the condition (D) is true (S100: YES), the PU 92 acquires the steering angle θh (S102). Next, the PU 92 sets the target steering angle α1* according to the steering angle θh (S104). Then, the PU 92 executes control in which the steering angle α1 is set as a control amount and the target steering angle α1* is set as a target value of the control amount (S106).

[0070] When the PU 92 completes the processes of S98 and S106, or when a negative determination is made in the process of S100, the PU 92 temporarily ends the series of processes shown in FIG. "Actions and Effects of the Present Embodiment" Figure 8 shows an example of using the reverse assist mode.

[0071] 8(a) shows an example in which the articulated vehicle 10 is moved forward to a reverse start position. During this period, the tractor 20 is steered by operating the steering wheel 50. 8(b) shows an example in which the articulated vehicle 10 is moved backward using the reverse assist mode. During this period, the target virtual steering angle α2* is determined by the operation of the steering wheel 50.

[0072] FIG. 8(c) shows an example in which the tractor 20 is separated from the trailer 30 and travels by itself. That is, when the reverse assist mode is OFF, the PU 92 sets the steering angle θh as a variable indicating an instruction for steering the tractor 20. Then, the PU 92 controls the steering angle α1 according to the steering angle θh. On the other hand, when the reverse assist mode is ON, the PU 92 sets the steering angle θh as a variable indicating an instruction for steering the trailer 30. Then, the PU 92 controls the virtual steering angle α2 according to the steering angle θh.

[0073] In this way, the means for inputting instructions to steer the tractor 20 and the means for inputting instructions to steer the trailer 30 are the same hardware, that is, the steering wheel 50. This eliminates the need to add a dedicated input means for giving instructions to steer the trailer 30.

[0074] FIG. 9 shows an example in which the reverse assist mode is switched from the OFF state to the ON state. FIG. 9(a) shows a state in which the steering wheel 50 is in a neutral position in the reverse assist mode OFF state. Therefore, the front wheels 22 as steered wheels of the tractor 20 are in a straight-ahead state. Also, an example is shown in which the trailer 30 faces right in the reverse assist mode OFF state. Therefore, the virtual steering angle α2 does not correspond to a straight-ahead state. In this state, when the reverse assist mode is switched to the ON state, the PU 92 turns the steering wheel 50 to the right. As a result, the steering angle θh is displaced so as to match the virtual steering angle α2, which is the traveling direction of the hitch point C1.

[0075] 9B shows a state in which the steering wheel 50 is in a neutral position when the reverse assist mode is OFF. In this example, the travel direction of the hitch point C1 is also a straight forward direction. Therefore, even if the reverse assist mode is switched to ON, the PU 92 does not displace the steering wheel 50.

[0076] FIG. 9(c) shows a state in which the steering wheel 50 is in a neutral position in the reverse assist mode OFF state. Therefore, the front wheels 22 as the steered wheels of the tractor 20 are in a straight-ahead state. Also, a case in which the trailer 30 faces left in the reverse assist mode OFF state is shown. Therefore, the virtual steering angle α2 does not correspond to a straight-ahead state. In this state, when the reverse assist mode is switched to the ON state, the PU 92 turns the steering wheel 50 leftward. As a result, the steering angle θh is displaced so as to match the virtual steering angle α2, which is the traveling direction of the hitch point C1.

[0077] 9(d) shows an example in which the hitch angle β is excessively large when the reverse assist mode is OFF, causing the jackknife phenomenon. In this case, when the reverse assist mode is switched ON, the PU 92 matches the steering angle θh to the maximum virtual steering angle α2th. Then, the PU 92 vibrates the steering wheel 50.

[0078] <Correspondence> The correspondence between the matters in the above embodiment and the matters described in the above "Means for solving the problem" column is as follows. In the following, the correspondence is shown for each number of the means for solving the problem described in the "Means for solving the problem" column. [1, 11-13] The control device of the articulated vehicle corresponds to the ADASECU90. The input unit corresponds to the steering wheel 50. The switching determination process corresponds to the processes of S90 and S100. The tractor steering process corresponds to the processes of S102-S104. The trailer steering process corresponds to the processes of S92-S98. [2] The consistency process corresponds to the process of S26. [3] The consistency process corresponds to the process of S28. [4] The deviation notification process corresponds to the process of S56 reflecting the process of S54. [5, 6] The reaction force application process corresponds to the process of S56 reflecting the process of S50. [7] The consistency process corresponds to the process of S74. [8] The reduction process corresponds to the process of S34 and S80. [9] The switching notification process corresponds to the processes of S22 and S72.

[10] The target virtual steering angle setting process corresponds to the process of S94. The virtual steering angle control process corresponds to the processes of S96 and S98.

[0079] <Other embodiments> This embodiment can be modified as follows: This embodiment and the following modifications can be combined with each other to the extent that no technical contradiction occurs.

[0080] "Regarding target virtual steering angle setting process" The target virtual steering angle α2* does not necessarily have to be a value obtained by performing a predetermined conversion on the steering angle θh. For example, the target virtual steering angle setting process may be a process of substituting the steering angle θh for the target virtual steering angle α2*.

[0081] "About trailer steering processing" The trailer steering process is not limited to a process that executes feedback control in which the virtual steering angle α2 is used as a control variable and the target virtual steering angle α2* is used as a target value of the control variable. For example, the process may execute open-loop control in which the virtual steering angle α2 is used as a control variable.

[0082] The trailer steering process does not necessarily have to be a process that uses the virtual steering angle α2 as the control amount. For example, the process may use the radius of curvature of the travel path of the trailer 30 as the control amount. Also, for example, the process may use the travel path of the trailer 30 itself as the control amount.

[0083] "About deviation notification processing" When the magnitude of the virtual steering angle α2 exceeds the magnitude of the maximum virtual steering angle α2th, the process of notifying the driver of this fact is not limited to the process of applying vibration to the steering wheel 50. For example, the process may be a process of changing the color displayed on the display device. Here, the display device may be a device that displays an image of the rear of the tractor 20. Furthermore, the display device may be a device that is provided on the steering wheel 50 and conveys a message by using colors.

[0084] The departure notification process may be executed on the condition that the transient flag F1 is "0." In other words, for example, the departure notification process does not have to be executed when the process of S28 is completed. "About reaction force application processing" The reaction force application process is not limited to a process in which the reaction force is variably set according to the virtual steering angle α2 before the virtual steering angle α2 reaches the maximum virtual steering angle α2th. For example, the reaction force may be constant until the virtual steering angle α2 reaches the maximum virtual steering angle α2th.

[0085] "About the alignment process" The process of changing the steering angle θh so that the steering angle θh and the virtual steering angle α2 are consistent when the reverse assist mode is switched from the off state to the on state is not essential. For example, the process of changing the virtual steering angle α2 so that the steering angle θh and the virtual steering angle α2 are consistent when the reverse assist mode is switched from the off state to the on state may be performed. Note that the process of matching the steering angle θh and the virtual steering angle α2 is not essential when the reverse assist mode is switched from the off state to the on state.

[0086] The process of changing the steering angle θh so that the steering angle θh and the turning angle α1 are consistent when the reverse assist mode is switched from the on state to the off state is not essential. For example, the process of changing the turning angle α1 so that the steering angle θh and the turning angle α1 are consistent when the reverse assist mode is switched from the on state to the off state may be performed. Note that the process of matching the steering angle θh and the turning angle α1 is not essential when the reverse assist mode is switched from the on state to the off state.

[0087] "About switching notification processing" The process of notifying the driver that the reverse assist mode has been switched from an off state to an on state is not limited to the process of vibrating the steering wheel 50. In other words, the process of notifying the driver that the state has shifted from one in which the steering angle α1 can be adjusted by operating the steering wheel 50 to one in which the virtual steering angle α2 can be adjusted is not limited to the process of vibrating the steering wheel 50. For example, the process may be a process of changing the color displayed on the display device. Here, the display device may be a device that displays an image of the rear of the tractor 20. The display device may also be a device that is provided on the steering wheel 50 and communicates a message by color.

[0088] The process of notifying the driver that the reverse assist mode has been switched from an on state to an off state is not limited to the process of vibrating the steering wheel 50. In other words, the process of notifying the driver that the state has shifted from one in which the virtual steering angle α2 can be adjusted to one in which the turning angle α1 can be adjusted by operating the steering wheel 50 is not limited to the process of vibrating the steering wheel 50. For example, the process may be a process of changing the color displayed on the display device. Here, the display device may be a device that displays an image of the rear of the tractor 20. The display device may also be a device that is provided on the steering wheel 50 and communicates a message by color.

[0089] "About the decline process" It is not essential to execute the process of S34. For example, if the steering wheel 50 is operated while the steering angle θh is being changed so that the steering angle θh matches the virtual steering angle α2 when the reverse assist mode is switched from the OFF state to the ON state, the following may be performed. That is, the process of changing the steering angle θh so that the steering angle matches the virtual steering angle α2 may be stopped. In that case, the steered angle α1 may be operated to control the virtual steering angle α2 in response to the operation of the steering wheel 50.

[0090] It is not essential to execute the process of S80. For example, if the steering wheel 50 is operated while the steering angle θh is being changed so that the steering angle θh and the turning angle α1 are consistent with each other as the reverse assist mode is switched from the on state to the off state, the following may be performed. That is, the process of changing the steering angle θh so that the steering angle θh is consistent with the turning angle α1 may be stopped. In that case, the turning angle α1 may be controlled in response to the operation of the steering wheel 50.

[0091] "About the subject of processing when reverse assist mode is off" In the above embodiment, the matching process when the reverse assist mode is off is a process in which the ADASECU90 transmits a command signal to the turning control device 70, but this is not limited to the above. For example, the matching process when the reverse assist mode is off may be executed by the turning control device 70 independently of an instruction from the ADASECU90.

[0092] "About the input section" The input unit for inputting the intention to steer the tractor 20 or the trailer 30 is not limited to the steering wheel 50. For example, it may be a joystick.

[0093] "About the steering system" For example, a clutch may be provided to switch between a power transmission state and a power cut-off state between the steering wheel 50 and the front wheels 22. In this case, the clutch may be in an engaged state when the reverse assist mode is in an off state. In other words, the tractor steering process may be performed with the clutch in an engaged state.

[0094] "About the control device" The ADASECU 90 and the steering control device 70 may be integrally configured. The control device is not limited to a device equipped with a PU 92 and a storage device 94 and executing software processing. For example, the control device may be equipped with a dedicated hardware circuit such as an ASIC that performs hardware processing of at least a part of what was processed by software in the above embodiment. That is, the control device may have any of the following configurations (a) to (c). (a) A processing device that executes all of the above processing according to a program, and a program storage device such as a storage device that stores the program. (b) A processing device and a program storage device that execute a part of the above processing according to a program, and a dedicated hardware circuit that executes the remaining processing. (c) A dedicated hardware circuit that executes all of the above processing. Here, there may be a plurality of software execution devices equipped with a processing device and a program storage device, and a plurality of dedicated hardware circuits.

[0095] "About Computers" The computer that executes the control programs such as the reverse assist program 94a is not limited to the computer mounted on the combination vehicle 10. For example, the computer may be configured by both the PU 52 mounted on the combination vehicle 10 and a mobile terminal of the driver. In that case, for example, the process of S16 may be executed by the mobile terminal.

[0096] "About the vehicle" The articulated vehicles are not limited to those shown in FIG. [Explanation of symbols]

[0097] 10…Articulated vehicle 20…Tractor 30…Trailer 40…Ball joint 42…Axis 50…Steering wheel 52...Reaction motor 54…Inverter 60...Rack and pinion mechanism 62...Steering motor 64…Inverter 70...Steering control device 90…ADASECU

Claims

1. The present invention is applied to a combination vehicle including a tractor and a trailer towed by the tractor, The tractor includes an input unit and steering wheels. The control unit is configured to execute a switching determination process, a tractor steering process, and a trailer steering process, the switching determination process is a process for determining whether the reverse assist mode is in an on state or an off state of the reverse assist mode, the tractor steering process is a process of steering the tractor in response to an input operation on the input unit when the reverse assist mode is in an off state, The trailer steering process is a process of manipulating the steering angle of the steered wheels to steer the trailer in response to an input operation to the input unit when the reverse assist mode is on and power transmission between the input unit and the steered wheels is interrupted.

2. configured to perform a matching process; 2. The control device for combined vehicles according to claim 1, wherein the matching process includes, when the reverse assist mode is switched from an OFF state to an ON state, a process of changing a state of the input unit so as to match a state of the trailer when the combined vehicles are traveling.

3. 3. A control device for an articulated vehicle according to claim 2, wherein the matching process includes a process for displacing the input unit to a position where the state of the trailer matches a state corresponding to a boundary of the allowable range, when the state of the trailer falls outside the allowable range.

4. configured to perform deviation notification processing; 2. The control device for articulated vehicles according to claim 1, wherein the deviation notification process includes a process for notifying the driver that a state of the trailer deviates from an allowable range while the trailer steering process is being performed.

5. A reaction force application process is configured to be performed, 2. A control device for an articulated vehicle according to claim 1, wherein the reaction force applying process applies a reaction force against the operation of the input unit in accordance with the operation state of the input unit when the reverse assist mode is on, and includes a process of making the reaction force when the steering state results in a small turning radius of the trailer equal to or greater than the reaction force when the steering state results in a large turning radius of the trailer.

6. 6. A control device for an articulated vehicle according to claim 5, wherein the reaction force application process includes a process for increasing an increase in the magnitude of the reaction force relative to a unit amount of displacement of the input portion as the state of the trailer approaches a boundary of an allowable range.

7. configured to perform a matching process; 2. The control device for an articulated vehicle according to claim 1, wherein the matching process includes a process of changing the state of the input unit so as to match the steering angle of the steered wheels when the reverse assist mode is switched from an on state to an off state of the reverse assist mode.

8. configured to perform a degradation process; 8. The control device for an articulated vehicle according to claim 2, wherein the reduction process includes a process of reducing a displacement speed of the input unit when the driver touches the input unit while the matching process is being performed.

9. A switching notification process is configured to be executed, 8. The control device for articulated vehicles according to claim 2, wherein the switching notification process includes a process of notifying the input unit prior to the displacement of the input unit due to the matching process.

10. The trailer steering process includes a target virtual steering angle setting process and a virtual steering angle control process, the target virtual steering angle setting process is a process of setting a target virtual steering angle in response to an input operation on the input unit, The target virtual steering angle is a target value of a virtual steering angle, The virtual steering angle is a variable indicating a traveling direction of a connection point between the trailer and the tractor, 2. The control device for an articulated vehicle according to claim 1, wherein the virtual steering angle control process is a process for controlling the steered angle of the steered wheels by a control operation amount in which the virtual steering angle is used as a control amount and the target virtual steering angle is a target value of the control amount.

11. The control device for an articulated vehicle according to claim 1 , wherein the input unit is a steering wheel.

12. A method for controlling an articulated vehicle, comprising the step of executing each of the processes in the control device for an articulated vehicle according to claim 1.

13. A control program for an articulated vehicle, which causes a computer to execute each of the processes in the control device for an articulated vehicle according to claim 1.

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