Control device for articulated vehicles, control method for articulated vehicles, and control program for articulated vehicles

Abstract

To provide a device for controlling a combination vehicle, which can grasp a behavior of a trailer to be taken from the current state of the combination vehicle.SOLUTION: A PU 52 receives a target value of an advancing direction in a connection part of a trailer and a tractor through a user interface 80 operated by a driver. The PU 52 operates a steering system 60 so as to bring the advancing direction close to the target value, and controls the steering angle of the steering wheel of the tractor. The PU 52 calculates a predicted track of the trailer in accordance with the steering angle or the like. The PU 52 displays the predicted track on a display device 82.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] For example, Patent Document 1 listed below describes a control device that displays the time it takes for the hitch angle to return to zero in an articulated vehicle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Patent No. 10,112,646 Summary of the Invention [Problem to be solved by the invention]

[0004] With the above control system, it is difficult for the driver to continuously monitor the behavior of the trailer. [Means for solving the problem]

[0005] The 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, and is configured to execute state quantity acquisition processing, predicted trajectory information calculation processing, and display processing, wherein the state quantity acquisition processing is processing for acquiring state quantities of the articulated vehicle, the predicted trajectory information calculation processing is processing for calculating predicted trajectory information of the trailer in accordance with the state quantities, and the display processing is processing for displaying the predicted trajectory information by operating a display device.

[0006] In the above configuration, information about the predicted trajectory of the trailer predicted based on the state quantities is displayed, allowing the driver to understand the possible behavior of the trailer based on the current state of the articulated vehicles.

[0007] 2. A control device for an articulated vehicle as set forth in claim 1 above, wherein the articulated vehicle is equipped with an interface for the driver to indicate a target virtual steering angle, the target virtual steering angle being a target value for the virtual steering angle and the virtual steering angle being a variable indicating the direction of travel at the point where the trailer and the tractor are connected, and is configured to execute target virtual steering angle acquisition processing and steering processing, the target virtual steering angle acquisition processing being processing for acquiring the target virtual steering angle in response to an input operation by the driver to the interface, the predicted trajectory information calculation processing being processing for using the virtual steering angle as input to calculate a predicted trajectory of the trailer when the actual virtual steering angle is brought as close as possible to the target virtual steering angle within a range where the magnitude of the steering angle of the tractor is not more than an upper limit value, the display processing being processing for displaying the predicted trajectory, and the steering processing being processing for controlling the steering angle of the tractor so as to bring the virtual steering angle close to the target virtual steering angle.

[0008] In the above configuration, the control device controls the steering angle of the tractor, but the target virtual steering angle is specified by the driver. Therefore, compared to when the control device performs everything, including setting the target virtual steering angle, the demands on the control device can be reduced. Here, the virtual steering angle can be controlled by steering the tractor, but the range of possible virtual steering angles is limited by the range of possible steering angles. Therefore, in the above configuration, a predicted trailer trajectory is calculated for bringing the actual virtual steering angle as close as possible to the target virtual steering angle within a range where the magnitude of the steering angle is equal to or less than an upper limit. This allows the predicted trajectory to be a feasible trajectory for the trailer.

[0009] 3. A control device for articulated vehicles as described in 2 above, configured to execute a target trajectory calculation process, wherein the target trajectory calculation process is a process of inputting the target virtual steering angle and calculating a target trajectory, which is the trajectory of the trailer when the virtual steering angle is set to the target virtual steering angle, and the display process includes a process of displaying the target trajectory in addition to the predicted trajectory.

[0010] In articulated vehicles, when the hitch angle becomes relatively large, the trailer's behavior tends to remain almost unchanged regardless of the steering angle setting. In such cases, the displayed predicted trajectory remains almost unchanged even when the driver significantly changes the target virtual steering angle. In such situations, there is a concern that the driver may be confused by the fact that the predicted trajectory remains unchanged despite the change in the target virtual steering angle. In response to this, the above configuration also displays a target trajectory that is determined ignoring the range of possible steering angles. The target trajectory changes significantly in response to changes in the target virtual steering angle, even in situations where the trailer's behavior remains almost unchanged regardless of the steering angle setting. Therefore, the divergence between the predicted trajectory and the target trajectory notifies the driver that the trailer's behavior remains almost unchanged regardless of the steering angle setting.

[0011] 4. The control device for articulated vehicles according to claim 2, wherein the state quantity acquisition processing includes processing for acquiring a hitch angle, the hitch angle being the angle between the fore-and-aft direction of the tractor and the fore-and-aft direction of the trailer, the predicted trajectory information calculation processing includes target steering angle calculation processing, upper limit guard processing, and displacement prediction processing, the target steering angle calculation processing includes processing for calculating a target steering angle that is a target value for the steering angle of the tractor using the target virtual steering angle and the hitch angle as inputs, the upper limit guard processing is processing for setting the magnitude of the target steering angle to the upper limit value when the magnitude of the target steering angle exceeds the upper limit value, the displacement prediction processing includes processing for predicting displacement of the trailer using the target steering angle that has been subjected to the upper limit guard processing as input, and the steering processing includes processing for bringing the virtual steering angle closer to the target virtual steering angle by bringing the steering angle closer to the target steering angle.

[0012] In the above configuration, the target steering angle can be set to a value that realizes the target virtual steering angle as much as possible under the condition that the magnitude of the target steering angle is equal to or less than the upper limit value. 5. A control device for articulated vehicles as set forth in claim 4 above, configured to execute hitch angle prediction processing, the hitch angle prediction processing being processing that predicts a future value of the hitch angle using as input the target steering angle that has been subjected to the upper limit guard processing, and configured to execute three processes multiple times: the target steering angle calculation processing that uses as input the predicted hitch angle; the hitch angle prediction processing that uses as input the target steering angle that has been subjected to the upper limit guard processing; and the displacement prediction processing that uses as input the predicted hitch angle and the target steering angle that has been subjected to the upper limit guard processing.

[0013] There is a predetermined correlation between the virtual steering angle, hitch angle, and steering angle. Therefore, when the hitch angle changes, the target steering angle that realizes the target virtual steering angle changes. Therefore, in the above configuration, by performing the three processes of target steering angle calculation process, hitch angle prediction process, and displacement prediction process multiple times, it is possible to calculate a predicted trajectory over a relatively long period of time with high accuracy.

[0014] 6. A control device for combined vehicles as set forth in any one of 2 to 5 above, configured to execute a determination process, the determination process being a process for determining whether or not the combined vehicle is in a reverse assist mode, the reverse assist mode being a process for realizing a reverse process for the combined vehicle by the steering process, and the display process being configured to be executed in the reverse assist mode.

[0015] Controlling the reverse of a combination vehicle requires advanced driving skills. In this regard, the above configuration reduces the burden on the driver of steering the tractor by executing steering processing in reverse assist mode. Furthermore, the display processing can provide useful information when the driver instructs the direction of travel of the trailer.

[0016] 7. The control device for an articulated vehicle as set forth in claim 6, wherein the display process is continued even when the articulated vehicle switches from reverse to forward in the reverse assist mode.

[0017] If the trailer's behavior is inappropriate during reverse control of the articulated vehicle, the driver may move the articulated vehicle forward to restart reverse control. In this case, by continuing the display processing, the driver can understand how far forward the articulated vehicle should be to achieve the desired trailer behavior.

[0018] 8. The control device for articulated vehicles as set forth in 7 above, which is configured to execute a cancellation process, the cancellation process being a process of canceling the reverse assist mode when the forward traveling speed of the articulated vehicles becomes equal to or greater than a threshold value.

[0019] When the forward traveling speed is high, it is thought that the driver does not want reverse control and would like to move the combined vehicle. Therefore, with the above configuration, by canceling the reverse assist mode when the forward traveling speed is equal to or greater than the threshold, it is possible to save the driver the trouble of manually canceling the reverse assist mode.

[0020] 9. The control device for articulated vehicles according to any one of 1 to 8 above, wherein the display processing includes processing for superimposing the predicted trajectory information on an image of the outside of the articulated vehicles taken by a camera. In the above configuration, predicted trajectory information is superimposed on the camera image, making it easier to accurately grasp the behavior of the trailer.

[0021] 10. The control device for articulated vehicles according to any one of 1 to 8 above, wherein the display processing includes processing for superimposing the predicted trajectory information on a bird's-eye view of the vicinity of the articulated vehicles. In the above configuration, predicted trajectory information is superimposed on the bird's-eye view, allowing the behavior of the trailer to be viewed from above.

[0022] 11. A control method for articulated vehicles, comprising the step of executing each of the processes described in any one of 1 to 10 above. 12. A control program for articulated vehicles that causes a computer to execute each of the processes described in any one of 1 to 10 above. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a perspective view showing a configuration of an articulated vehicle according to one embodiment. [Figure 2] FIG. 2 is a block diagram showing the configuration of a control system according to the embodiment. [Figure 3] 4 is a diagram illustrating an example of reverse control of an articulated vehicle according to the embodiment; FIG. [Figure 4] FIG. 2 is a diagram showing a model of an articulated vehicle according to the embodiment. [Figure 5] 3 is a flowchart showing a procedure of a process executed by a control device according to the embodiment. [Figure 6] 3 is a flowchart showing a procedure of a process executed by a control device according to the embodiment. [Figure 7] 10(a) and 10(b) are diagrams showing a method for displaying a predicted trajectory. [Figure 8] 10(a) and 10(b) are diagrams showing display examples according to the embodiment. [Figure 9] 10(a) and 10(b) are diagrams showing display examples according to the embodiment. [Figure 10] 10(a) and 10(b) are diagrams showing display examples according to the embodiment. [Figure 11] 10(a) and 10(b) are time charts illustrating the control of the virtual steering angle according to the embodiment. [Figure 12] 10(a) and 10(b) are diagrams showing a display example according to a modified example of the embodiment. [Figure 13] 10(a) and 10(b) are diagrams showing a display example according to a modified example of the embodiment. [Figure 14] 10(a) and 10(b) are diagrams showing a display example according to a modified example of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0024] Hereinafter, an embodiment will be described with reference to the drawings. "Configuration of articulated vehicles" As shown in Figure 1, the articulated vehicle 10 has a tractor 20 and a trailer 30. The tractor 20 has 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 also shows an example of 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.

[0025] 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 so that the trailer 30 can rotate about an axis 42. The axis 42 extends along the height direction of the tractor 20.

[0026] Figure 2 shows some of the components provided on the tractor 20. As shown in Figure 2, the tractor 20 is equipped with a control device 50. The control device 50 operates a steering system 60, a drive system 62, and a braking system 64 to control the control variables of the articulated vehicle 10, which is the control target. The control variables include vehicle speed, traveling direction, and hitch angle. The hitch angle is the angle between the fore-and-aft direction of the tractor 20 and the fore-and-aft direction of the trailer 30.

[0027] Steering system 60 includes a steering actuator that steers the steered wheels. The steered wheels are, for example, front wheels 22 shown in FIG. 1. Note that steering system 60 may also include a steering control device that operates the steering actuator. In this case, "control device 50 operates steering system 60" means that control device 50 outputs a command signal to the steering control device.

[0028] The drivetrain 62 includes at least one of an internal combustion engine and a rotating electric machine as a thrust generating device for the vehicle. The drivetrain 62 may also include a drive control device that controls the internal combustion engine and the rotating electric machine. In this case, "the control device 50 operates the drivetrain 62" means that the control device 50 outputs a command signal to the drive control device.

[0029] The braking system 64 includes at least one of a device that decelerates the rotation of the wheels by frictional force and a device that decelerates the rotation of the wheels by converting the power of the wheels into electrical energy. The device that decelerates the rotation of the wheels by converting it into electrical energy may be shared with the rotating electric machine of the drive system. The braking system 64 may also include a braking control device that controls the device that decelerates the rotation of the wheels. In this case, "the control device 50 operates the braking system 62" means that the control device 50 outputs a command signal to the braking control device.

[0030] To control the control variable, the control device 50 refers to the steering angle α1 of the steered wheels detected by the steering angle sensor 70. The steering angle α1 is a value in which either the right turn or the left turn has a positive sign and the other has a negative sign. The steering angle α1 is the turning angle of the tires. Note that, for example, if the steering system 60 is equipped with a rack and pinion mechanism, the steering angle sensor 70 may be a sensor that detects the pinion angle. In that case, however, the control device 50 performs a process to convert the pinion angle into the turning angle of the tires. For convenience of explanation, the turning angle of the tires obtained by the above conversion process will be considered to be the detection value of the steering angle sensor 70 below.

[0031] The control device 50 also references the hitch angle β detected by the hitch angle sensor 72. The hitch angle β can be either positive or negative depending on the angle between the direction in which the tractor 20 moves from rear to front and the direction in which the trailer 30 moves from rear to front. For example, the sign of the hitch angle β may be positive when the direction in which the trailer 30 moves from rear to front deviates counterclockwise by less than 180 degrees from the direction in which the tractor 20 moves from rear to front. The control device 50 also references the wheel speeds ωw1 to ωw4 detected by the wheel speed sensor 74. The wheel speeds ωw1 and ωw2 are the rotational speeds of the right front wheel 22 and the left front wheel 22, respectively. The wheel speeds ωw3 and ωw4 are the rotational speeds of the right rear wheel 24 and the left rear wheel 24, respectively. The control device 50 also references image data Dp that indicates an image of the rear of the tractor 20 captured by the backup camera 76.

[0032] The control device 50 sets the control of the control amount according to the operation state of the user interface 80. The user interface 80 is used to communicate the user's intention to the control device 50, such as selecting either automatic driving or manual driving.

[0033] The control device 50 comprises a PU 52 and a storage device 54. The PU 52 is a software processing device comprising at least one of a CPU, a GPU, a TPU, etc. A reverse assist program 54a is stored in the storage device 54. The reverse assist program 54a is a program that prescribes commands for causing the PU 52 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 54a is a program that reduces the burden on the driver when driving in reverse.

[0034] That is, as shown in FIG. 3, when the articulated 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. For this reason, high driving skills are required for reverse control. The reverse assist process by the reverse assist program 54a assists the driver by controlling the steering angle α1 of the tractor 20. However, accelerator operation and brake operation are left to the driver. Furthermore, the reverse assist process leaves instructions for steering the trailer 30 to the driver. This is because if the control device 50 were to also set the steering of the trailer 30, it would place greater demands on the control device 50. By leaving some instructions to the driver, it is possible to assist reverse control with relatively simple processing.

[0035] "Model used by reverse assist processing" FIG. 4 shows a model of the articulated vehicle 10 used in the reverse assist process. In the model shown in FIG. 4, the pair of front wheels 22 of the tractor 20 are designated as front wheels C0, and the pair of rear wheels 24 of the tractor 20 are designated as rear wheels B1. That is, a two-wheel model is used for the tractor 20. The pair of wheels 32 of the trailer 30 are designated as wheels B2. The angle between the line defined by the front wheels C0 and hitch point C1 and the line defined by the hitch point C1 and wheel B2 is the hitch angle β. The hitch point C1 corresponds to the axle 42 in FIG. 1. The front wheel speed VC0, which is the speed of the front wheel C0, is a vector that moves in the direction of the steering angle α1. The steering angle α1 is modeled as the angle between the direction of travel of the front wheels C0 and the line defined by the front wheels C0 and hitch point C1. The direction of vehicle speed Vb1 is parallel to the line defined by the front wheels C0 and hitch point C1. In the following description, the sign of vehicle speed Vb1 when tractor 20 travels forward is assumed to be positive. The angle between the direction of vehicle speed Vb1 and the x-direction in FIG. 4 is angle θ1. The angle between the line connecting wheel B2 and hitch point C1 and the x-direction is angle θ2. The distance l1 between front wheel C0 and rear wheel B1, the distance h1 between rear wheel B1 and hitch point C1, and the distance l2 between hitch point C1 and wheel B2 are defined.

[0036] In this embodiment, the virtual steering angle α2 that quantifies the steering of the trailer 30 is defined as shown in Figure 4. That is, it is defined as the angle between the direction of the moving speed at the hitch point C1 and the front-rear direction of the trailer 30.

[0037] "Reverse assist processing" Figures 5 and 6 show the procedure for the reverse assist process. The process shown in Figures 5 and 6 is realized by the PU 52 repeatedly executing the reverse assist program 54a, for example, at a predetermined interval. Note that, below, the step numbers of each process are represented by numbers preceded by "S."

[0038] In the series of processes shown in FIGS. 5 and 6, the PU 52 first determines whether the reverse assist flag F is "1" (S10). When the reverse assist flag F is "1," it indicates that the vehicle is in a reverse assist mode in which reverse assist processing is executed. On the other hand, when the reverse assist flag F is "0," it indicates that the vehicle is not in the reverse assist mode. When the PU 52 determines that the reverse assist flag F is "0" (S10: NO), it determines whether the vehicle is in the reverse assist mode (S12). The PU 52 determines that the vehicle is in the reverse assist mode when a command to execute reverse assist processing is issued by an input operation on the user interface 80. When the PU 52 determines that the vehicle is in the reverse assist mode (S12: YES), it assigns "1" to the reverse assist flag F (S14).

[0039] On the other hand, when the PU 52 determines that the reverse assist flag F is "1" (S10: YES), the PU 52 determines whether the logical sum of the following conditions (A) and (B) is true (S16).

[0040] Condition (A): This is a condition that the reverse assist mode is cancelled by an input operation on the user interface 80. Condition (B): This condition states that the vehicle speed Vb1 is equal to or greater than the threshold value Vth. In other words, this condition states that the forward traveling speed of the tractor 20 is equal to or greater than the threshold value Vth. This processing is a condition that states that the driver has stopped reverse control of the combination vehicle 10 and is moving the combination vehicle 10 a large distance.

[0041] When the PU 52 determines that the above logical sum is true (S16: YES), it assigns "0" to the reverse assist flag F (S18). On the other hand, when the PU 52 determines that the logical sum is false (S16: NO) or when the processing of S14 is completed, the PU 52 acquires a target virtual steering angle α2* corresponding to an input operation on the user interface 80 (S20). The target virtual steering angle α2* is a target value of the virtual steering angle α2. In this embodiment, the target virtual steering angle α2* is instructed by the driver. Specifically, for example, the input operation may be realized by providing the user interface 80 with a dial that has a positive correlation with the virtual steering angle α2. Here, it is not essential that the rotation angle of the dial and the target virtual steering angle α2* are proportional to each other.

[0042] Next, the PU 52 calculates a target trajectory Trt of the trailer 30 using the target virtual steering angle α2* as an input (S22). Here, the PU 52 may calculate the target trajectory Trt using a two-wheel model in which the front wheels are steered at the hitch point C1 and the rear wheels B1 are the rear wheels. More specifically, the PU 52 may calculate the target trajectory Trt by calculating the curvature of the target trajectory Trt according to the target virtual steering angle α2* and the distance l2. The target trajectory Trt may be the trajectory of a representative point of the trailer 30. Here, the representative point may be, for example, a point at the center of the rear wheels B1. Alternatively, for example, the representative point may be the center of gravity of the trailer 30.

[0043] Next, the PU 52 acquires the hitch angle β and the vehicle speed Vb1 (S24). The hitch angle β is the most recent value detected by the hitch angle sensor 72. The vehicle speed Vb1 is calculated by the PU 52 in accordance with the wheel speeds ωw3 and ωw4. The vehicle speed Vb1 may be, for example, a simple average value of the wheel speeds ωw3 and ωw4.

[0044] Next, the PU 52 calculates the speed Vb2 of the wheel B2 (S25). More specifically, the PU 52 calculates this from a geometric relationship according to the hitch angle β and the vehicle speed Vb1. Next, the PU 52 initializes the angle θ1 (S26). Here, the PU 52 sets the angle θ1 to "90°." This setting is for aligning the fore-and-aft direction of the tractor 20 with the y direction of the coordinate system shown in FIG. 4.

[0045] Next, PU 52 calculates target steering angle α1*, which is the steering angle for realizing target virtual steering angle α2* (S28). The processing of S28 is a processing in which target virtual steering angle α2* and hitch angle β are input and target steering angle α1* is output. That is, according to the model shown in FIG. 4, the following equation (c1) holds between steering angle α1 and virtual steering angle α2.

[0046] α1=arctan{(l1 / h1)·tan(-α2-β)} …(c1) By replacing the virtual steering angle α2 on the right side of the above equation (c1) with the target virtual steering angle α2*, the left side becomes the target steering angle α1*.

[0047] PU 52 may calculate target steering angle α1* based on an equation corresponding to equation (c1). PU 52 may also perform map calculations to determine target steering angle α1*. This can be achieved by storing map data in advance in storage device 54. Here, the map data is data that uses target virtual steering angle α2* and hitch angle β as input variables and target steering angle α1* as an output variable. Note that map data is a set of data that includes discrete values ​​of input variables and values ​​of output variables corresponding to each of the input variable values. Furthermore, map calculations may be performed by determining, as a calculation result, the value of the output variable in the corresponding map data when the value of an input variable matches any of the input variable values ​​in the map data. Furthermore, map calculations may be performed by determining, as a calculation result, a value obtained by interpolating the values ​​of multiple output variables included in the map data when the value of an input variable does not match any of the input variable values ​​in the map data. Alternatively, the map calculation may be a process in which, if 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 the multiple input variables included in the map data is used as the calculation result.

[0048] Next, the PU 52 determines whether the magnitude of the target steering angle α1* is greater than an upper limit value α1th (S30). The upper limit value α1th is the maximum value that the steering angle α1 can take. This process is a process for determining whether the steering angle α1 that realizes the target virtual steering angle α2* can actually be realized. If the PU 52 determines that the target steering angle α1* is greater than the upper limit value α1th (S30: YES), it reduces the magnitude of the target steering angle α1* to the upper limit value α1th (S32).

[0049] When the processing of S32 is completed or when a negative judgment is made in the processing of S30, the PU 52 operates the steering system 60 to control the steering angle α1 to approach the target steering angle α1* (S34).

[0050] Shifting to FIG. 6, the PU 52 predicts the hitch angle β for a predetermined time τ in the future (S36). According to the model shown in FIG. 4, the amount of change Δβ in the hitch angle β during a predetermined time τ is expressed by the following equation (c2).

[0051] Δβ = -(Vb1 / l2)·sinβ·τ -{Vb1 / (l1·l2)}·(l2+h1·cosβ)·(tanα1*)·τ …(c2) In the process of S36, the PU 52 may calculate a predicted value of the hitch angle β by adding the change amount Δβ calculated by the above formula (c2) to the hitch angle β. Alternatively, the process of S36 may include a process in which the PU 52 calculates the change amount Δβ by map calculation with map data stored in advance. Here, the map data is data that uses the vehicle speed Vb1, the hitch angle β, and the target steering angle α1* as input variables and the change amount Δβ of the hitch angle β as an output variable.

[0052] Next, the PU 52 calculates the angle θ1 for a predetermined time τ in the future (S38). Here, the amount of change Δθ1 in the angle θ1 during the predetermined time τ is expressed by the following equation (c3). Δθ1=(Vb1 / l1)·tan(α1*) …(c3) In the process of S36, the PU 52 may calculate a predicted value of the angle θ1 by adding the change amount Δθ1 calculated by the above formula (c3) to the angle θ1. Alternatively, the process of S36 may be performed by the PU 52 calculating the change amount Δθ1 by map calculation using map data that has been stored in advance. Here, the map data is data that uses the vehicle speed Vb1 and the target steering angle α1* as input variables and the change amount Δθ1 as an output variable.

[0053] Next, the PU 52 assigns the sum of the hitch angle β calculated in the process of S36 and the angle θ1 calculated in the process of S38 to the angle θ2 a predetermined time τ into the future (S40). Next, the PU 52 inputs the vehicle speed Vb1 and angle θ1 and calculates the tractor position coordinate (xb1, yb1) a predetermined time τ into the future (S44). Here, the amount of change in the x-component xb1 of the tractor position coordinate over the predetermined time τ is "Vb1·cosθ1." Also, the amount of change in the y-component yb1 of the tractor position coordinate over the predetermined time τ is "Vb1·sinθ1."

[0054] Next, the PU 52 inputs the speed Vb2 and angle θ2 and calculates the trailer position coordinate (xb2, yb2) a predetermined time τ into the future (S46). Here, the amount of change in the x-component xb2 of the trailer position coordinate over the predetermined time τ is "Vb2·cosθ2." Also, the amount of change in the y-component yb2 of the trailer position coordinate over the predetermined time τ is "Vb2·sinθ2."

[0055] Next, the PU 52 temporarily stores the values ​​calculated by the processes of S28 to S32 and S36 to S46 in the storage device 54 (S48). That is, the PU 52 temporarily stores the tractor position coordinates (xb1, yb1), trailer position coordinates (xb2, yb2), angles θ1, θ2, target steering angle α1*, and hitch angle β in the storage device 54.

[0056] The PU 52 then determines whether the prediction interval has ended (S50). The prediction interval is an interval during which the combination vehicle 10 travels for a predetermined time. The predetermined time may be, for example, about several seconds. The prediction interval may have a positive correlation with the absolute value of the vehicle speed Vb1, but may also be independent of the vehicle speed Vb1.

[0057] When the PU 52 determines that the prediction interval has not ended (S50: NO), the process returns to S28. On the other hand, when the PU 52 determines that the prediction interval has ended (S50: YES), the PU 52 displays the predicted trajectory Trp and the target trajectory Trt on the display device 82 shown in FIG. 1 (S52).

[0058] Here, at the time when it is determined that the prediction interval has ended, memory device 54 stores N hitch angles β that are further in the future than the hitch angle β acquired by the processing of S24, where N is an integer equal to or greater than 2. These are predicted values ​​at timings spaced apart by a predetermined time τ from one another. Memory device 54 also stores tractor position coordinates (xb1, yb1), trailer position coordinates (xb2, yb2), angles θ1, θ2, and target steering angle α1* at timings synchronized with the N hitch angles β.

[0059] Here, the N trailer position coordinates (xb2, yb2) indicate the predicted positions of representative points of the trailer 30 that are spaced apart from each other by a predetermined time τ. Therefore, by connecting these, the predicted trajectory Trp can be obtained.

[0060] The processing of S52 may be processing to transmit N trailer position coordinates (xb2, yb2) to the display device 82. Alternatively, the processing of S52 may be processing to find a curve that fits the N trailer position coordinates (xb2, yb2) and transmit parameters that specify the curve to the display device 82. In this case, the communication load can be reduced. Furthermore, the display device 82 may have only a simple display function, so that the PU 52 generates an image to be displayed by the display device 82.

[0061] The display device 82 displays the predicted trajectory Trp and the target trajectory Trt superimposed on the image captured by the rear camera 76. 7(a) shows the predicted trajectory Trp obtained by connecting the trailer position coordinates (xb2, yb2) and the target trajectory Trt. According to the processing of S26, the trailer position coordinates (xb2, yb2) are coordinate components of a coordinate system in which the y-axis is parallel to the longitudinal direction of the tractor 20. However, in order to match the image of the backup camera 76, the PU 52 displays point cloud data or the like obtained by projectively transforming the trailer position coordinates (xb2, yb2) as shown in FIG. 7(b).

[0062] Fig. 8 shows an example of an image displayed on the display screen 82a of the display device 82. In detail, Fig. 8(a) shows the state of the articulated vehicle 10, and Fig. 8(b) shows an example of the display on the display screen 82a. In Fig. 8, the predicted trajectory Trp is shown by a solid line, and the target trajectory Trt is shown by a dashed line. However, on the actual display screen 82a, the predicted trajectory Trp and the target trajectory Trt may be distinguished by using different colors. The example shown in Fig. 8 shows a case where a driver wishes to make a right turn while reversing.

[0063] Figure 9 shows another example of an image displayed on the display screen 82a of the display device 82. Figures 9(a) and 9(b) correspond to Figures 8(a) and 8(b). The example shown in Figure 9 shows a case where it is desired to transition from a state of turning right while reversing to a state of going straight.

[0064] FIG. 10 shows another example of an image displayed on the display screen 82a of the display device 82. Note that FIGS. 10(a) and 10(b) correspond to FIGS. 8(a) and 8(b). The example shown in FIG. 10 shows a case where a user wishes to transition from a right turn to a left turn while reversing. In the display example shown in FIG. 10, the predicted trajectory Trp is significantly deviated from the target trajectory Trt. This is a state where the predicted trajectory Trp does not change even when the target virtual steering angle α2* is operated by an input operation to the user interface 80, due to the processing of S30 to S32. A situation where the predicted trajectory Trp does not change is likely to occur when the hitch angle β is large, as shown in FIG. 11.

[0065] Fig. 11(a) shows a case where the target virtual steering angle α2* is turned back when the hitch angle β is small, and Fig. 11(b) shows a case where the target virtual steering angle α2* is turned back when the hitch angle β is small.

[0066] As shown in FIG. 11, when the target virtual steering angle α2* is steered back while the hitch angle β is large, the virtual steering angle α2 cannot follow the target virtual steering angle α2*. In this way, if the predicted trajectory Trp does not change even when the target virtual steering angle α2* is operated, the driver may be confused and not understand why the predicted trajectory Trp does not change. In contrast, in this embodiment, by also displaying the target trajectory Trt, it is possible to notify the driver that if the difference between the target trajectory Trt and the predicted trajectory Trp is large, the virtual steering angle α2 cannot be set to the desired angle by steering the tractor 20.

[0067] According to the present embodiment described above, the following actions and effects can be further obtained. (1) The PU 52 sets one of the axes of the coordinate system that defines the trailer coordinate components to be parallel to the longitudinal direction of the tractor 20. This allows the trailer coordinate components to be easily aligned with the image of the rear camera 76.

[0068] (2) The PU 52 performs a projective transformation on the trailer coordinate components, thereby allowing the trailer coordinate components to be properly aligned with the image of the backup camera 76. <Correspondence> The correspondence between the matters in the above embodiment and the matters described in the "Means for Solving the Problem" column is as follows. Below, 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, 12] State quantity acquisition processing corresponds to the processing of S20, S24, and S25. Predicted trajectory information calculation processing corresponds to the processing of S26 to S32 and S36 to S50. Display processing corresponds to the processing of S52. The display device corresponds to display device 82. [2] Target virtual steering angle acquisition processing corresponds to the processing of S20. The virtual steering angle corresponds to virtual steering angle α2. The upper limit value corresponds to upper limit value α1th. Steering processing corresponds to the processing of S34. The connection point corresponds to ball joint 40 or hitch point C1. [3] Target trajectory calculation processing corresponds to the processing of S22. [4] Target steering angle calculation processing corresponds to the processing of S28. Upper limit guard processing corresponds to the processing of S30 and S32. The displacement prediction process corresponds to the processes of S36 to S46. [5] The hitch angle prediction process corresponds to the process of S36. [6] The judgment process corresponds to the process of S12. [7] Corresponds to condition (B) of S16. [8] Corresponds to transitioning to the process of S18 when a positive judgment is made in the process of S16. [9] Corresponds to Figures 8 to 10 and 12.

[10] Corresponds to Figures 13 and 14.

[0069] <Other embodiments> This embodiment can be modified as follows: This embodiment and the following modifications can be combined and implemented within the scope of technical compatibility.

[0070] "Status quantity acquisition process" In the process of S24, the hitch angle β detected by the hitch angle sensor 72 is acquired, but this is not limiting. For example, an estimated value of the hitch angle β may be acquired. This can be achieved by, for example, estimating the hitch angle β to zero when the vehicle has continued traveling straight for a predetermined distance, and then successively updating the hitch angle β using the change amount Δβ obtained using the above equation (c2). Note that the change amount Δβ here is not a predicted value of the future change amount of the hitch angle β, but an estimated value of the change amount.

[0071] "About virtual steering angle" The virtual steering angle, which is a variable that quantifies the steering of the trailer, is not limited to the definition exemplified in the above embodiment. For example, the virtual steering angle may be defined as the angle between the front-rear direction of the tractor 20 and the traveling direction of the hitch point C1.

[0072] "About the process of calculating predicted orbit information" The processes of S30, S32, etc. are not essential for the process of calculating the predicted trajectory of the trailer 30 when bringing the actual virtual steering angle α2 as close as possible to the target virtual steering angle α2* within a range in which the magnitude of the steering angle α1 is equal to or less than the upper limit value α1th. For example, the process may include a process of converting the upper limit value α1th into the upper limit value of the magnitude of the virtual steering angle α2 based on an inverse equation of the above equation (c1). In this case, the PU 52 may perform upper limit guard processing on the target virtual steering angle α2* using the upper limit value of the magnitude of the virtual steering angle α2. The PU 52 may then perform the processes of S34 and onward using the value obtained by converting the target virtual steering angle α2* after the upper limit guard processing into the target steering angle α1* using the above equation (c1).

[0073] The initial value of the angle θ1 in the trajectory prediction does not necessarily have to be 90°. For example, by comparing the map data with the longitudinal direction of the tractor 20, the angle formed between a predetermined axis in a coordinate system arbitrarily defined on the map data and the longitudinal direction of the tractor 20 may be used as the initial value of the angle θ1 in the predicted trajectory information calculation process.

[0074] "About steering processing" The steering process for controlling the steering angle α1 so that the virtual steering angle α2 approaches the target virtual steering angle α2* is not limited to the process executed in the reverse assist mode. For example, it may be a process for automatically steering the tractor 20 when the combination vehicle 10 is driven forward.

[0075] "Conditions for canceling steering processing" In the above embodiment, the condition for canceling the reverse assist mode, which is the condition for canceling the steering process, is the logical sum of condition (A) and condition (B), but this is not limited to this. For example, instead of condition (B), the condition may be that the articulated vehicle 10 has moved forward. Also, for example, only condition (A) may be used.

[0076] "About display processing" It is not necessary to display the target trajectory Trt in addition to the predicted trajectory Trp of the trailer 30. When only the predicted trajectory Trp is displayed, for example, a feasible region for the trailer 30's travel trajectory may also be displayed. In this case, if the trailer 30's travel path changes very little even when the steering angle α1 is changed, the width of the region will be narrow. Therefore, it is possible to inform the driver that it will be difficult to change the trailer 30's travel trajectory even when the virtual steering angle α2 is changed. Also, for example, instead of displaying the region, if the width of the region is equal to or smaller than a predetermined value and the driver operates the target virtual steering angle α2*, it may be possible to inform the driver that it will be difficult to change the trailer 30's trajectory by operating the target virtual steering angle α2*. This may be done by displaying visual information, or by audio notification.

[0077] For example, as illustrated in FIGS. 8 and 9, when the difference between the predicted orbit Trp and the target orbit Trt is equal to or less than a predetermined value, only the predicted orbit Trp may be displayed. That is, the PU 72 repeatedly determines whether the difference between the predicted orbit Trp and the target orbit Trt is equal to or less than a predetermined value. If it determines that the difference is equal to or less than the predetermined value, the PU 72 may not display the target orbit Trt. Here, the difference between the predicted orbit Trp and the target orbit Trt being equal to or less than a predetermined value may be, for example, equal to or less than a predetermined value between the positions of the predicted orbit Trp and the target orbit Trt at the same time. Alternatively, it may be equal to or less than a predetermined value between the positions of the predicted orbit Trp and the target orbit Trt at the same time.

[0078] The predicted orbit information to be displayed is not limited to the predicted orbit Trp. For example, as illustrated in FIG. 12, the predicted orbit Trp may have a certain width. Note that FIGS. 12(a) and 12(b) correspond to FIGS. 8(a) and 8(b). In FIG. 12, the area defined by the boundaries TrpL and TrpR of the pair of predicted orbits is displayed as dots. Furthermore, the area defined by the boundaries TrtL and TrtR of the pair of target orbits is hatched. However, on the actual display screen 82a, these two areas may be distinguished by different colors.

[0079] The process of providing a width to the predicted trajectory Trp may be implemented, for example, as follows, depending on whether or not a negative determination is made in the process of S30. That is, if a negative determination is made in the process of S30, PU 52 may execute the processes of S36 to S46 using the target steering angle α1* calculated in the process of S28, for example, "α1*+δ" and "α1*-δ." Furthermore, if a negative determination is made in the process of S30, PU 52 may execute the processes of S36 to S46 using the target steering angle α1* calculated in the process of S32 and a value whose absolute value is smaller by a predetermined amount.

[0080] The process of giving a width to the target trajectory Trt may be a process of calculating the boundaries TrtL and TrtR as follows: That is, the process of S22 may be performed using "α2*+δ" and "α2*-δ" determined by the target virtual steering angle α2* acquired by the process of S20.

[0081] Note that when the process of giving a range to the predicted trajectory Trp is executed, it is not essential to execute the process of giving a range to the target trajectory Trt. For example, a single trajectory may be displayed for the target trajectory Trt. Furthermore, when the process of giving a range to the predicted trajectory Trp is executed, it is not necessary to display any visual information regarding the target trajectory Trt.

[0082] For example, as described in the section "Regarding steering processing," when steering is automatically controlled while the articulated vehicle 10 is traveling forward, the predicted trajectory Trp of the tractor 20 can be superimposed on an image of the area ahead of the tractor 20.

[0083] The process of displaying the predicted trajectory Trp is not limited to the process of superimposing the predicted trajectory Trp on an image of the surroundings of the articulated vehicle 10 captured by a camera. For example, a bird's-eye view may be used, as illustrated in FIG. 13. FIGS. 13(a) and 13(b) correspond to FIGS. 8(a) and 8(b). This is particularly effective in the process of backing up assist in the articulated vehicle 10 when a specific trailer 30, such as a camper van, is in use. That is, as shown by the dashed-dotted line in FIG. 1, if the trailer 30 is high, the area behind the trailer 30 cannot be included in the image captured by the backup camera 76.

[0084] Note that the predicted orbit information to be superimposed on the bird's-eye view is not limited to the predicted orbit Trp. For example, as described above, an area obtained by adding a width to the predicted orbit Trp may be superimposed on the bird's-eye view and displayed.

[0085] In addition to displaying the predicted trajectory information of the trailer 30, the predicted trajectory information of the tractor 20 may also be displayed. In FIG. 14, the predicted trajectory Trp and the target trajectory Trt are superimposed on a bird's-eye view, and the predicted trajectory Tr1L at the left end and the predicted trajectory Tr1R at the right end of the tractor 20 are also displayed. FIGS. 14(a) and 14(b) correspond to FIGS. 8(a) and 8(b). Note that the method of displaying the predicted trajectory of the tractor 20 is not limited to displaying both the predicted trajectory Tr1L at the left end and the predicted trajectory Tr1R at the right end. For example, a single predicted trajectory, such as the predicted trajectory of the center of gravity of the tractor 20, may also be displayed. Alternatively, a wider area may be displayed, such as by marking the area between the predicted trajectory Tr1L at the left end and the predicted trajectory Tr1R at the right end.

[0086] It should be noted that the use of a bird's-eye view is not essential for the method of displaying the predicted trajectory information of the tractor 20 together with the predicted trajectory information of the trailer 30. For example, it may be superimposed on an image taken of the outside of the articulated vehicle 10. It is also not essential to display the target trajectory information of the trailer 30 at the same time.

[0087] The predicted trajectory information of the trailer 30 to be displayed does not necessarily have to be the predicted trajectory Trp or an area that is wider than the predicted trajectory Trp. For example, if the trailer 30 is not traveling in a straight line during manual steering of the articulated vehicle 10, a right or left arrow indicating the traveling direction of the trailer 30 may be displayed.

[0088] "About the control device" The control device is not limited to one equipped with a PU 52 and a storage device 54 and executing software processing. For example, it may be equipped with a dedicated hardware circuit, such as an ASIC, that performs hardware processing on at least a portion of what was software processed in the above embodiments. That is, the control device may have any of the following configurations (a) to (c): (a) equipped with 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) equipped with a processing device and program storage device that executes part of the above processing according to a program, and a dedicated hardware circuit that executes the remaining processing; or (c) equipped with a dedicated hardware circuit that executes all of the above processing. Here, there may be multiple software execution devices equipped with a processing device and a program storage device, and multiple dedicated hardware circuits.

[0089] "About Computers" The computer that executes control programs such as the reverse assist program 54a is not limited to a 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 the driver's mobile terminal. In that case, for example, the processing of S28 to S32 and S36 to S50 may be executed by the mobile terminal.

[0090] "About the vehicle" The articulated vehicles are not limited to the vehicles shown in FIG. [Explanation of symbols]

[0091] 10...Articulated vehicle 20...Tractor 22...Front wheel 24...Rear wheel 30...Trailer 32...Wheel 40...ball joint 42...Axis 50...Control device 82a…Display screen

Claims

1. The present invention is applied to a combination vehicle including a tractor and a trailer towed by the tractor, configured to execute a state quantity acquisition process, a predicted orbit information calculation process, and a display process; the state quantity acquisition process is a process for acquiring state quantities of the combination vehicles, the predicted trajectory information calculation process is a process of calculating predicted trajectory information of the trailer in accordance with the state quantity, the display process is a process of displaying the predicted orbit information by operating a display device, the articulated vehicle is provided with an interface for a driver to specify 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 traveling direction of a connection point between the trailer and the tractor, configured to execute a target virtual steering angle acquisition process and a steering process, the target virtual steering angle acquisition process is a process of acquiring the target virtual steering angle in response to an input operation by the driver to the interface, the predicted trajectory information calculation process is a process that uses the virtual steering angle as an input to calculate a predicted trajectory of the trailer when the actual virtual steering angle is brought as close as possible to the target virtual steering angle within a range in which the magnitude of the steering angle of the tractor is equal to or less than an upper limit value, the display process is a process of displaying the predicted trajectory, A control device for articulated vehicles, wherein the steering process is a process for controlling the steering angle of the tractor so that the virtual steering angle approaches the target virtual steering angle.

2. configured to execute a target trajectory calculation process, the target trajectory calculation process is a process of inputting the target virtual steering angle and calculating a target trajectory, which is a trajectory of the trailer when the virtual steering angle is set to the target virtual steering angle, The control device for an articulated vehicle according to claim 1 , wherein the display process includes a process of displaying the target trajectory in addition to the predicted trajectory.

3. the state quantity acquisition process includes a process of acquiring a hitch angle, The hitch angle is an angle between the front-rear direction of the tractor and the front-rear direction of the trailer, the predicted trajectory information calculation process includes a target steering angle calculation process, an upper limit guard process, and a displacement prediction process, the target steering angle calculation process includes a process of calculating a target steering angle that is a target value of the steering angle of the tractor using the target virtual steering angle and the hitch angle as inputs, the upper limit guard process is a process for setting the magnitude of the target steering angle to the upper limit value when the magnitude of the target steering angle exceeds the upper limit value, the displacement prediction process includes a process of predicting a displacement of the trailer using the target steering angle that has been subjected to the upper limit guard process as an input, 2. The control device for articulated vehicles according to claim 1, wherein the steering process includes a process of bringing the virtual steering angle closer to the target virtual steering angle by bringing the steering angle closer to the target steering angle.

4. configured to perform a hitch angle prediction process; the hitch angle prediction process is a process for predicting a future value of the hitch angle using the target steering angle that has been subjected to the upper limit guard process as an input, 4. A control device for articulated vehicles according to claim 3, wherein the three processes of the target steering angle calculation process, which receives the predicted hitch angle as an input, the hitch angle prediction process, which receives the target steering angle after the upper limit guard process as an input, and the displacement prediction process, which receives the predicted hitch angle and the target steering angle after the upper limit guard process as inputs, are executed a plurality of times.

5. configured to perform a determination process; The determination process is a process for determining whether or not the vehicle is in a reverse assist mode, the reverse assist mode is a process for realizing a reverse process of the combination vehicle by the steering process, 2. The control device for articulated vehicles according to claim 1, wherein the display process is executed in the reverse assist mode.

6. 6. The control device for an articulated vehicle according to claim 5, wherein the display process is continued even when the articulated vehicle switches from reverse to forward in the reverse assist mode.

7. configured to perform a cancellation process, 7. The control device for an articulated vehicle according to claim 6, wherein the cancellation process is a process for canceling the reverse assist mode when the forward traveling speed of the articulated vehicle is equal to or greater than a threshold value.

8. The control device for an articulated vehicle according to claim 1 , wherein the display process includes a process of superimposing the predicted trajectory information on an image of the outside of the articulated vehicle captured by a camera.

9. The control device for articulated vehicles according to claim 1 , wherein the display process includes a process of superimposing the predicted trajectory information on a bird's-eye view of the vicinity of the articulated vehicles.

10. 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.

11. A control program for articulated vehicles that causes a computer to execute each of the processes in the control device for articulated vehicles according to claim 1.

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