Articulated vehicle control device, articulated vehicle control method, and articulated vehicle control program

Abstract

Control devices (80, 90) are configured to execute acquisition processing and notification processing. The acquisition processing is processing for acquiring a value of a turning angular velocity variable. The turning angular velocity variable is a variable indicating a changing rate of a turning angle of a tractor. The notification processing is processing for notifying, by operating a notification device, that there is a risk of a trailer (10) swaying when the absolute value of the value of the turning angular velocity variable is equal to or greater than a threshold value. The notification device (116) is an interface for transmitting information to a person.

Description

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

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

[0002] For example, Patent Document 1 listed below describes a control device for dealing with the so-called sway phenomenon, in which the trailer of a coupled vehicle sways. This control device reduces the sway of the trailer by controlling the brakes when the sway phenomenon occurs.

[0003] US Patent Application Publication No. 2019 / 0001944

[0004] In articulated vehicles, it is more desirable to prevent the sway phenomenon from occurring in the first place than to reduce the sway of the trailer after the sway phenomenon has occurred.

[0005] One aspect of the present disclosure provides a control device for an articulated vehicle. The articulated vehicle includes a tractor and a trailer towed by the tractor. The control device is configured to execute an acquisition process and a notification process. The acquisition process is a process for acquiring a value of a turning angular velocity variable. The turning angular velocity variable is a variable that indicates the rate of change of the turning angle of the tractor. The notification process is a process for notifying a person that there is a risk of a sway phenomenon occurring in the trailer by operating a notification device if the absolute value of the turning angular velocity variable is equal to or greater than a threshold. The notification device is an interface for communicating information to a person.

[0006] Another aspect of the present disclosure provides a control method for an articulated vehicle. The articulated vehicle includes a tractor and a trailer towed by the tractor. The control method includes executing an acquisition process and a notification process. The acquisition process is a process for acquiring a value of a turning angular velocity variable. The turning angular velocity variable is a variable that indicates the rate of change of the turning angle of the tractor. The notification process is a process for notifying a person that there is a risk of a sway phenomenon occurring in the trailer by operating a notification device if the absolute value of the turning angular velocity variable is equal to or greater than a threshold. The notification device is an interface for communicating information to a person.

[0007] Another aspect of the present disclosure provides a control program for an articulated vehicle. The articulated vehicle includes a tractor and a trailer towed by the tractor. The control program includes instructions to cause a computer to execute an acquisition process and a notification process. The acquisition process is a process for acquiring the value of a turning angular velocity variable. The turning angular velocity variable is a variable that indicates the rate of change of the turning angle of the tractor. The notification process is a process for notifying a person that there is a risk of a sway phenomenon occurring in the trailer by operating a notification device if the absolute value of the turning angular velocity variable is equal to or greater than a threshold. The notification device is an interface for communicating information to a person.

[0008] FIG. 1 is a perspective view showing the configuration of an articulated vehicle according to a first embodiment; FIG. 2 is a diagram showing the configuration of a control system according to the same embodiment; FIG. 3 is a flowchart showing the procedure of processing executed by the control system according to the same embodiment; FIG. 4 is a flowchart showing the procedure of processing executed by a steering ECU according to the same embodiment; FIG. 5 is a flowchart showing the procedure of processing executed by a steering ECU according to a second embodiment; FIG. 6 is a flowchart showing the procedure of processing executed by a steering ECU according to a third embodiment; FIG. 7 is a flowchart showing the procedure of processing executed by a steering ECU according to a fourth embodiment; and FIG. 8 is a flowchart showing the procedure of processing executed by a steering ECU according to a fifth embodiment.

[0009] <First embodiment> A first embodiment will be described below with reference to the drawings. "Configuration of articulated vehicle" As shown in Figure 1, articulated vehicle 10 includes a tractor 20 and a trailer 30. 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 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 trailer 30. Trailer 30 has wheels 32. The wheels 32 include two wheels, a right wheel and a left wheel.

[0010] 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.

[0011] Figure 2 shows some of the components provided in the tractor 20. As shown in Figure 2, a reaction force is applied to a steering wheel 52 in a steering system 50 provided in the combination vehicle 10 by a reaction motor 54. The reaction force is a torque with an opposite sign to the torque applied to the steering wheel 52 by the driver. The output voltage of an inverter 56 is applied to the terminals of the reaction motor 54.

[0012] The steering system 50 also includes a front wheel actuator Af. In the front wheel actuator Af, power is applied from a front wheel steering motor 60 to the front wheels 22 included in the steering system 50. The output voltage of an inverter 62 is applied to the terminals of the front wheel steering motor 60.

[0013] The steering ECU 80 controls the torque of the reaction force motor 54 to control the control amount of the steering wheel 52, which is the object of control. Here, the control amount is the reaction force. The steering ECU 80 also controls the torque of the front wheel steering motor 60 to control the control amount of the front wheels 22, which are the object of control. Here, the control amount is the steering angle of the front wheels 22. The steering angle is the turning angle of the tires of the front wheels 22.

[0014] To control the control amount, the steering ECU 80 refers to the steering torque Th detected by the torque sensor 85. The steering torque Th is the torque input to the steering wheel 52. To control the control amount, the steering ECU 80 also refers to the steering angle θh detected by the steering angle sensor 86. To control the control amount, the steering ECU 80 also refers to the rotation angle θmf of the front wheel steering motor 60 detected by the rotation angle sensor 87.

[0015] The steering ECU 80 includes a PU 82 and a storage device 84. The PU 82 is a software processing device including at least one of a CPU, a GPU, a TPU, etc. The storage device 84 stores a steering control program 84a.

[0016] The tractor 20 includes a drivetrain 100. The drivetrain 100 includes at least one of an internal combustion engine and a rotating electric machine as a vehicle thrust generating device. The tractor 20 includes a braking system 102. The braking system 102 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 drivetrain.

[0017] The tractor 20 is equipped with an ADASECU 90. The ADASECU 90 operates the steering system 50, drive system 100, and braking system 102 to control the control variables of the combination vehicle 10, which is the control target. The control variables include vehicle speed and traveling direction. The drive system 100 may also include a drive control device that controls the control variables of the internal combustion engine and rotating electrical machine, which are the control targets. In this case, "the ADASECU 90 operates the drive system 100" means that the ADASECU 90 outputs a command signal to the drive control device. Furthermore, the braking system 102 may also include a braking control device that controls the control variable of a device that decelerates the rotation of the wheels, which is the control target. In this case, "the ADASECU 90 operates the braking system 102" means that the ADASECU 90 outputs a command signal to the braking control device. Furthermore, "the ADASECU 90 operates the steering system 50" means that the ADASECU 90 outputs a command signal to the steering ECU 80.

[0018] The ADASECU 90 refers to the vehicle speed V detected by the vehicle speed sensor 112. The ADASECU 90 also refers to the tractor yaw rate rt detected by the tractor-side yaw rate sensor 114 in order to control the control variable. The ADASECU 90 is capable of communicating with a user interface 116. The user interface 116 is an interface into which information from the driver is input. Here, the input of information from the driver includes input of the driver's intention. The input of the driver's intention includes input of whether automatic steering or manual steering is desired. The input of information from the driver also includes input of information about the trailer 30, etc. The user interface 116 is also an interface for outputting information to the driver.

[0019] 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, etc. An assist program 94a is stored in the storage device 94. The assist program 94a defines commands for executing automatic steering processing, etc.

[0020] "Processing for Understanding Trailer Status" Figure 3 shows the procedure for processing for understanding the status of the trailer. The processing shown in Figure 3 is executed while the ADASECU 90 and the steering ECU 80 communicate with each other. In detail, the processing on the left side of Figure 3 is realized by the PU 92 of the ADASECU 90 repeatedly executing an assist program 94a, for example, at a predetermined cycle. Also, the processing on the right side of Figure 3 is realized by the PU 82 of the steering ECU 80 repeatedly executing a steering control program 84a, for example, at a predetermined cycle. Note that, hereinafter, the step numbers of each processing are represented by numbers preceded by "S."

[0021] In the series of processes shown in Figure 3, the PU 92 first determines whether an input operation has been performed via the user interface 116 to input information regarding whether the trailer 30 is coupled to the tractor (S10). If the PU 92 determines that an input operation has been performed (S10: YES), the PU 92 determines whether information indicating that the trailer 30 is coupled has been input (S12). If the PU 92 determines that information indicating that the trailer 30 is coupled has been input (S12: YES), the PU 92 sets the traveling mode to the trailer towing mode (S14). On the other hand, if the PU 92 determines that information indicating that the trailer 30 is not coupled has been input (S12: NO), the PU 92 sets the traveling mode to the tractor-only mode (S16). After completing the processes of S14 and S16, the PU 92 outputs data indicating the traveling mode to the steering ECU 80 (S18).

[0022] The PU 92 also determines whether trailer information has been input via the user interface 116 (S20). The trailer information includes information on at least one of the following three items: the weight of the trailer 30, the position of the center of gravity of the trailer 30, and the length of the trailer 30. If the PU 92 determines that trailer information has been input (S20: YES), it outputs the trailer information to the steering ECU 80 (S22).

[0023] The PU 92 temporarily terminates the series of processes shown on the left side of Fig. 3 when it completes the process of S22 or when it makes a negative determination in the processes of S10 and S20. Meanwhile, the PU 82 of the steering ECU 80 determines whether it has received the data related to the driving mode output by the process of S18 or the data related to the trailer information output by the process of S22 (S30). If it determines that it has received the data (S30: YES), the PU 82 stores the received data in the storage device 84 (S32).

[0024] When the PU 82 completes the process of S32 or when a negative determination is made in the process of S30, the PU 82 temporarily terminates the series of processes shown on the right side of Fig. 3. The processes of S10 and S12 correspond to the towing information acquisition process, and the processes of S20 and S22 correspond to the trailer information acquisition process.

[0025] "Countermeasures against sway phenomenon" Fig. 4 shows a procedure for a process aimed at suppressing the occurrence of sway phenomenon. The series of processes shown in Fig. 4 is realized by the PU 82 repeatedly executing the steering control program 84a, for example, at a predetermined interval.

[0026] 4, the PU 82 first determines whether the vehicle is in the trailer towing mode (S40). If the PU 82 determines that the vehicle is in the trailer towing mode (S40: YES), the PU 82 sets the threshold value ωhth based on the trailer information output by the process of S22 (S42).

[0027] The PU 82 determines whether the flag F is "1" (S44). The flag F is set to "1" when a process for notifying the driver that a situation is likely to cause a sway phenomenon is being executed. The flag F is set to "0" when the process is not being executed. If the PU 82 determines that the flag F is "0", the PU 82 acquires the steering angle θh, the steering speed ωh, and the vehicle speed V (S46). The steering speed ωh is calculated by the PU 82 using time-series data of the steering angle θh.

[0028] The PU 82 determines whether the following condition A is satisfied (S48): Condition A: The absolute value of the steering speed ωh is equal to or greater than a threshold value ωhth. The threshold value ωhth is set according to the lower limit of the absolute value of the steering speed ωh at which the sway phenomenon is likely to occur.

[0029] When the PU 82 determines that the condition A is satisfied (YES in S48), the PU 82 determines whether the following condition B is satisfied (S50). Condition B is a condition that the absolute value of the steering angle θh is equal to or greater than a threshold value θhth. Here, the threshold value θhth is set according to the lower limit of the absolute value of the angle at which the sway phenomenon is likely to occur.

[0030] When the PU 82 determines that the condition B is satisfied (YES in S50), it determines whether the following condition C is satisfied (S52). Condition C: The steering angle θh and the steering speed ωh have the same sign. This condition is established in consideration of the fact that the steering angle θh and the steering speed ωh tend to have the same sign when a sway phenomenon occurs.

[0031] If the PU 82 determines that the condition C is satisfied, it then determines whether the following condition D is satisfied (S54). Condition D: The vehicle speed V is equal to or greater than a threshold value Vth. The threshold value Vth is set according to the lower limit of the absolute value of the vehicle speed V at which the sway phenomenon is likely to occur.

[0032] When the PU 82 determines that condition D is met (S54: YES), it assigns "1" to flag F (S56). Then, the PU 82 notifies the driver that the vehicle is in a situation where sway is likely to occur by vibrating the steering wheel 52 for a predetermined period of time (S58). The execution condition for the process of S58 is a condition that the logical product of conditions A to D is true. In this embodiment, it is defined that the vehicle is in a situation where sway is likely to occur when the logical product of conditions A to D is true.

[0033] On the other hand, if the PU 82 determines that the flag F is "1" (S44: YES), it determines whether a predetermined time has elapsed since the start of the process of S58 (S60). If the PU 68 determines that the predetermined time has elapsed (S60: YES), it assigns "0" to the flag F (S62).

[0034] 4 when the processing of S58 and S62 is completed or when a negative determination is made in the processing of S40, S48 to S54, and S60. The steering speed ωh corresponds to the steering angular velocity variable. The processing of S46 corresponds to the acquisition processing. The processing of S58 corresponds to the notification processing.

[0035] "Operations and Effects of the Present Embodiment" In the trailer towing mode, when the logical product of the above conditions A to D is true, the PU 82 vibrates the steering wheel 52. This makes it possible to notify the driver in a situation where a sway phenomenon is likely to occur. This allows the driver to consciously perform driving operations to avoid the occurrence of a sway phenomenon.

[0036] Second Embodiment A second embodiment will be described below with reference to the drawings, focusing on differences from the first embodiment.

[0037] "Countermeasures against sway phenomenon" Figure 5 shows a procedure for processing aimed at suppressing the occurrence of sway phenomenon. The series of processing shown in Figure 5 is realized by the PU 82 repeatedly executing the steering control program 84a, for example, at a predetermined interval. Note that in Figure 5, processing corresponding to processing shown in Figure 4 is given the same step number for convenience.

[0038] 5, when the PU 82 determines that the vehicle is in the trailer towing mode (YES in S40), it selects map data for setting the threshold value ωhth in accordance with the trailer information (S42a). The map data is data in which the vehicle speed V is an input variable and the threshold value ωhth is an output variable. Appropriate map data corresponding to each of the different trailer information is pre-stored in the storage device 84.

[0039] Furthermore, when completing the processing of S46, the PU 82 determines whether the above condition A is satisfied (S48a). Here, the threshold value ωhth is set by the PU 82 in accordance with the vehicle speed V at each time. The PU 82 changes the threshold value ωhth in accordance with the vehicle speed V under the condition that the threshold value ωhth when the vehicle speed V is high is equal to or less than the threshold value ωhth when the vehicle speed V is low. Specifically, the PU 82 performs map calculation to determine the threshold value ωhth using the map data selected in the processing of S42a.

[0040] Note that map data is 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, map calculation may be a process in which, when the value of an input variable matches one of the input variable values ​​in the map data, the value of the corresponding output variable in the map data is the calculation result. Furthermore, map calculation may be a process in which, when the value of an input variable does not match any of the input variable values ​​in the map data, the calculation result is a value obtained by interpolating the values ​​of multiple output variables included in the map data. Alternatively, map calculation may be a process in which, when the value of an input variable does not match any of the input variable values ​​in the map data, the calculation result is the value of the output variable in the map data that corresponds to the closest value of the multiple input variables included in the map data.

[0041] Furthermore, in the description "changing B according to A while satisfying the condition that when A is large, B is equal to or less than B when A is small," the case where A is large and the case where A is small refer to the relative relationship of magnitude when comparing the two. For example, "when A is large" corresponds to the case where "A is a first value," and "when A is small" corresponds to the case where "A is a second value smaller than the first value." This means that, depending on the settings of the first and second values, B when A is the first value may be smaller than B when A is the second value.

[0042] If the PU 82 determines that condition A is true, the process proceeds to S50. If the PU 82 determines that the logical product of conditions A to C is true (S52: YES), the process proceeds to S56. The process of S48a corresponds to the change process.

[0043] "Functions and Effects of the Present Embodiment" In trailer towing mode, the PU 82 vibrates the steering wheel 52 when the logical product of the above conditions A to C is true. Here, the PU 82 sets the threshold value ωhth that defines condition A according to the vehicle speed V. Therefore, compared to when the threshold value ωhth is a fixed value, it is possible to more accurately identify whether a situation is prone to sway depending on whether condition A is satisfied.

[0044] Third Embodiment Hereinafter, a third embodiment will be described with reference to the drawings, focusing on differences from the first embodiment.

[0045] "Countermeasures against sway phenomenon" Figure 6 shows a procedure for processing aimed at suppressing the occurrence of sway phenomenon. The series of processing shown in Figure 6 is realized by the PU 82 repeatedly executing the steering control program 84a, for example, at a predetermined interval. Note that in Figure 6, processing corresponding to processing shown in Figure 4 is given the same step number for convenience.

[0046] As shown in FIG. 6 , in this embodiment, the PU 82 executes the processes of S40, S42, and S46 to S54 to determine whether conditions A to D are satisfied. If the PU 82 determines that the logical product of conditions A to D is true (YES in S54), the PU 82 notifies the user that the vehicle is in a situation where a sway phenomenon is likely to occur by operating the user interface 116 (S58a). That is, the PU 82 causes the display device of the user interface 116 to display visual information warning the user that the vehicle is in a situation where a sway phenomenon is likely to occur. The PU 82 also causes the speaker of the user interface 116 to output an audible warning that the vehicle is in a situation where a sway phenomenon is likely to occur. Note that the process of S58a may be a process in which the PU 82 requests the ADASECU 90 to operate the user interface 116.

[0047] When the PU 82 completes the process of S58a or when a negative determination is made in the processes of S40 and S48 to S54, the PU 82 temporarily ends the series of processes shown in Fig. 6. Incidentally, the process of S58a corresponds to the notification process.

[0048] Fourth Embodiment Hereinafter, a fourth embodiment will be described with reference to the drawings, focusing on differences from the first embodiment.

[0049] "Countermeasures against sway phenomenon" Fig. 7 shows a procedure for a process aimed at suppressing the occurrence of sway phenomenon. The series of processes shown in Fig. 7 is realized by the PU 82 repeatedly executing the steering control program 84a, for example, at a predetermined interval.

[0050] In the series of processes shown in Figure 7, the PU 82 first acquires the steering angle θh detected by the steering angle sensor 86 and the vehicle speed V detected by the vehicle speed sensor 112 (S60). The PU 82 calculates a target front wheel steering angle base value θfb* based on the steering angle θh (S62). The target front wheel steering angle base value θfb* is a base value for the target value of the steering angle of the front wheels 22. The target front wheel steering angle base value θfb* is set by the PU 82 to a value that has a positive correlation with the steering angle θh.

[0051] Next, the PU 82 determines whether the flag F used in the processing of FIG. 4 is "1" (S64). If the PU 82 determines that the flag F is "1" (S64: YES), it acquires the tractor yaw rate rt (S66). Next, the PU 82 selects map data that determines the coefficient Ka based on the trailer information (S68). The map data is data in which the vehicle speed V is an input variable and the coefficient Ka is an output variable. Note that the storage device 84 has a plurality of map data pre-stored according to the trailer information.

[0052] The PU 52 inputs the tractor yaw rate rt to the following phase lead compensation filter, which is defined by the coefficient Ka, to obtain the correction amount Δθf, which is the output (S70): (1+Ka·s·T) / (1+s·T) Note that the above equation uses the Laplace operator s and the time constant T. The coefficient Ka in the above equation is calculated by the PU 82 using a map in accordance with the vehicle speed V.

[0053] The PU 82 then subtracts the correction amount Δθf from the target front wheel steering angle base value θfb* and assigns the result to the target front wheel steering angle θf* (S72).On the other hand, if the PU 82 determines that the flag F is "0" (S64: NO), it assigns the target front wheel steering angle base value θfb* to the target front wheel steering angle θf* (S74).

[0054] When the processing of S72 and S74 is completed, the PU 82 acquires the front wheel steering angle θf (S76). The front wheel steering angle θf is calculated by the PU 82 based on the rotation angle θmf. The PU 82 calculates a feedback control manipulated variable in which the front wheel steering angle θf is the controlled variable and the target front wheel steering angle θf* is the controlled variable's target value, and substitutes this manipulated variable for the target front wheel torque Tf* (S78). The PU 82 then operates the inverter 62 by outputting an operation signal MSf corresponding to the target front wheel torque Tf* to the inverter 62 (S80). Here, if the target front wheel torque Tf* is an amount converted into the torque of the front wheel steering motor 60, the operation signal MSf becomes a signal for bringing the torque of the front wheel steering motor 60 closer to the target front wheel torque Tf*.

[0055] When the PU 82 completes the processing of S80, it temporarily terminates the series of processing steps shown in FIG. 7. Incidentally, the processing steps of S66 to S72 and S76 to S80 correspond to the deceleration processing. "Functions and Effects of the Present Embodiment" The PU 82 sets the target front wheel steering angle base value θfb* in accordance with the steering angle θh. The PU 82 then substitutes the target front wheel steering angle base value θfb* for the target front wheel steering angle θf*. However, when executing the processing of S58, the PU 82 substitutes the value obtained by subtracting the correction amount Δθf from the target front wheel steering angle base value θfb* for the target front wheel steering angle base value θfb*. The correction amount Δθf is the output value of a phase lead compensation filter to which the tractor yaw rate rt is input, and therefore has a positive correlation with the tractor yaw rate rt. Therefore, the target front wheel steering angle θf* in the trailer towing mode is set to a value that reduces the absolute value of the tractor yaw rate rt below the target front wheel steering angle base value θfb*.

[0056] Since an increase in the absolute value of the yaw rate is a factor that causes the sway phenomenon, the correction amount Δθf can reduce the factor that causes the sway phenomenon. <Fifth Embodiment> Hereinafter, the fifth embodiment will be described with reference to the drawings, focusing on the differences from the fourth embodiment.

[0057] "Countermeasures against sway phenomenon" Figure 8 shows a procedure for processing aimed at suppressing the occurrence of sway phenomenon. The series of processing shown in Figure 8 is realized by the PU 82 repeatedly executing the steering control program 84a, for example, at a predetermined interval. For convenience, in Figure 8, processing corresponding to processing shown in Figure 7 is assigned the same step number.

[0058] 8, when the PU 82 completes the process of S62, it determines whether the vehicle is in the trailer towing mode (S90). If the PU 82 determines that the vehicle is in the trailer towing mode (S90: YES), it executes the processes of S66 to S70. Next, the PU 82 determines whether flag F is "1" (S92). If the PU 82 determines that flag F is "1" (S92: YES), it corrects the correction amount Δθf so that its absolute value is larger than before correction (S94).

[0059] The PU 82 executes the process of S72 when it has completed the process of S94 or when it has made a negative determination in the process of S92. On the other hand, when it has determined that it is in the tractor-only mode (S90: NO), the PU 82 proceeds to the process of S74.

[0060] When the PU 82 completes the processes of S72 and S74, it executes the processes of S76 to S80. When the PU 82 completes the process of S80, it temporarily ends the series of processes shown in FIG. 8. The process of S94 corresponds to the deceleration process. The processes of S66 to S70 and S72 to S80 executed when a negative determination is made in the process of S92 correspond to the towing process. The processes executed when a positive determination is made in the process of S92 correspond to the deceleration process.

[0061] "Functions and Effects of the Present Embodiment" The PU 82 sets the target front wheel steering angle base value θfb* in accordance with the steering angle θh. In the tractor-only mode, the PU 82 assigns the target front wheel steering angle base value θfb* to the target front wheel steering angle θf*. On the other hand, in the trailer towing mode, the PU 82 assigns the value obtained by subtracting the correction amount Δθf from the target front wheel steering angle base value θfb* to the target front wheel steering angle base value θfb*. The correction amount Δθf is the output value of a phase-lead compensation filter to which the tractor yaw rate rt is input, and therefore has a positive correlation with the tractor yaw rate rt. Therefore, the target front wheel steering angle θf* in the trailer towing mode is set to a value that reduces the absolute value of the tractor yaw rate rt below the target front wheel steering angle base value θfb*.

[0062] Generally, when the tractor 20 is towing the trailer 30, the absolute value of the yaw rate is more likely to increase even during the same turning operation compared to when the tractor is not towing the trailer 30. In other words, even if the steering wheel 52 is operated in the same manner in the trailer towing mode and the tractor-only mode, the yaw response in the trailer towing mode is more likely to be greater. This increase in the absolute value of the yaw rate can cause the sway phenomenon.

[0063] In contrast, the correction amount Δθf prevents the yaw response from becoming large in the trailer towing mode when the steering wheel 52 is operated equally in the pair of modes.

[0064] Furthermore, when the process of S58 is executed, the PU 82 sets the correction amount Δθf to an amount that has the same sign as the correction amount Δθf when the process of S58 is not executed and has a larger absolute value than the correction amount Δθf when the process of S58 is not executed. This makes it possible to further reduce the yaw response in situations where sway is likely to occur. Therefore, it is possible to more reliably suppress the occurrence of sway.

[0065] <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.

[0066] "Regarding the steering angular velocity variable" The steering angular velocity variable does not necessarily have to be the steering velocity ωh. For example, the steering angular velocity variable may be the rate of change of the steering angle of the front wheels 22 itself. In short, the steering angular velocity variable may be any quantity that has a positive correlation with the rate of change of the steering angle of the front wheels 22.

[0067] "Regarding the Towing Information Acquisition Process" The towing information acquisition process is not limited to the process of acquiring information input via the user interface 116. For example, a camera may be provided at the rear of the tractor 20, and the presence or absence of a trailer may be determined from an image captured by the camera.

[0068] It is not essential to execute the towing information acquisition process. Regarding the notification process: In the process of S58a, only one of the two pieces of information, audio information and visual information, may be output.

[0069] The process of notifying the driver that a sway phenomenon is likely to occur using the steering wheel 52 is not limited to the process of applying vibration to the steering wheel 52. For example, the process may be a process of controlling the torque of the reaction force motor 54 so that the force required to rotate the steering wheel 52 becomes larger.

[0070] It is not essential that the process of outputting at least one of the two pieces of information, audio information and visual information, and the process of notifying the driver that a sway phenomenon is likely to occur using the steering wheel 52 are executed exclusively. The notification process may include both of these processes.

[0071] 7 and 8, the PU 82 sets the coefficient Ka according to the vehicle speed V, but this is not limitative. For example, the PU 82 may set the time constant T according to the vehicle speed V. Furthermore, for example, the coefficient Ka may be a value that is set according to the trailer information and that is not dependent on the vehicle speed V.

[0072] The process in which the tractor yaw rate rt is input and the corrected target front wheel steering angle base value θfb* is output is not limited to the process using phase lead compensation. For example, the process may be a process in which the target front wheel steering angle base value θfb* is corrected by a value obtained by multiplying the time differential value of the tractor yaw rate rt by a proportional gain. In this case, the PU 82 may set the proportional gain based on at least one of the information about the trailer 30 and the vehicle speed V.

[0073] The process in which the yaw rate is input and the corrected value of the target front wheel steering angle base value θfb* is output is not limited to a process in which only the tractor yaw rate rt is input. For example, the process may be a process in which the yaw rate of the trailer 30 is input. Also, for example, the process may be a process in which both the tractor yaw rate rt and the yaw rate of the trailer 30 are input.

[0074] As a towing process, the PU 82 may execute a process for setting a target value for the steering angle of the rear wheels 24 in accordance with the target front wheel steering angle θf*. This process can be employed when the tractor 20 is equipped with an actuator for steering the rear wheels 24. This process may be implemented by the PU 82, for example, by multiplying the target front wheel steering angle θf* by a gain and substituting the resultant value for the target value of the rear wheels 24. This gain is an operation amount for open-loop control for bringing the slip angle closer to zero. Here, the PU 82 may change the gain G in accordance with at least one of the trailer information and the vehicle speed V.

[0075] The towing process, which includes the process of setting the target value for the rear wheels 24 in accordance with the target front wheel steering angle θf*, is not limited to the process described above. For example, the towing process may include the process of setting a target steering angle for the trailer 30 in addition to the target value for the rear wheels 24 in accordance with the target front wheel steering angle θf*. This process can be employed when the trailer 30 is equipped with an actuator that steers the wheels 32.

[0076] As a towing process, the PU 82 may execute a process of controlling the torque of the reaction motor 54 so that the force required for the driver to operate the steering wheel 52 becomes larger.

[0077] The object operated by the towing process is not limited to the steering system, and may be, for example, at least one of the drive system 100 and the braking system 102. For example, the PU 92 may operate at least one of the drive system 100 and the braking system 102 so that the relative magnitude of the driving force of the outer wheels of the tractor 20 to the driving force of the inner wheels of the tractor 20 is smaller than when the trailer 30 is not towed.

[0078] It is not essential that trailer information be input to the towing process. "Regarding the damping process" It is not essential that the damping process be a process in which the yaw rate is input and the corrected value of the target front wheel steering angle base value θfb* is output. The damping process may be any process for damping the yaw response described in the above section "Regarding the towing process."

[0079] Regarding the Input Unit: The input unit through which the driver inputs his / her steering intention is not limited to the steering wheel 52. The input unit may be, for example, a joystick.

[0080] Regarding the Control Device: In the above embodiment, part of the processing executed by the steering ECU 80 may be executed by the ADASECU 90.

[0081] The ADASECU 90 and the steering ECU 80 may be integrated. The control device is not limited to one that executes software processing. For example, a dedicated hardware circuit, such as an ASIC, that executes at least part of the processing executed in the above embodiment may be included. That is, the control device may include a processing circuit having any of the following configurations (a) to (c): (a) A processing circuit that includes a processing device that executes all of the above processing in accordance with a program and a program storage device, such as a memory device, that stores the program. (b) A processing circuit that includes a processing device and program storage device that executes part of the above processing in accordance with a program, and a dedicated hardware circuit that executes the remaining processing. (c) A processing circuit that includes a dedicated hardware circuit that executes all of the above processing. Here, there may be multiple software execution devices that include a processing device and a program storage device. Also, there may be multiple dedicated hardware circuits.

[0082] Regarding the Control Entity: For example, part of the above process may be executed by the driver's mobile terminal. That is, for example, the process executed by the ADASECU 90 in FIG. 3 and the process of S58a may be executed by the mobile terminal.

[0083] Other: It is not essential that the steering system of the tractor 20 include a steer-by-wire system. In other words, the steering system may be a system in which the steering wheel 52 and the front wheels 22 are connected.

Claims

1. This applies to articulated vehicles comprising a tractor and a trailer towed by the tractor. It is configured to perform acquisition and notification processes, The aforementioned acquisition process is a process for acquiring the value of the steering angle velocity variable, The steering angle velocity variable is a variable that indicates the rate of change of the steering angle of the tractor, The notification process is a process that, when the absolute value of the steering angle velocity variable is greater than or equal to a threshold, notifies that there is a risk of the trailer swaying by operating the notification device. The notification device is an interface for transmitting information to a person, A control device for a coupled vehicle, wherein the execution conditions for the notification process include a condition that the sign of the steering angle velocity variable matches the sign of the steering angle.

2. This applies to articulated vehicles comprising a tractor and a trailer towed by the tractor. It is configured to perform acquisition and notification processes, The aforementioned acquisition process is a process for acquiring the value of the steering angle velocity variable, The steering angle velocity variable is a variable that indicates the rate of change of the steering angle of the tractor, The notification process is a process that, when the absolute value of the steering angle velocity variable is greater than or equal to a threshold, notifies that there is a risk of the trailer swaying by operating the notification device. The notification device is an interface for transmitting information to a person, It is configured to execute a trailer information acquisition process to acquire trailer information, The trailer information includes at least one of the following three items: the position of the trailer's center of gravity, the total weight of the trailer, and the length of the trailer. A control device for a coupling vehicle, configured to perform a modification process to change the threshold value according to the trailer information.

3. The control device for a coupled vehicle according to claim 2, wherein the execution conditions for the notification process include a condition that the vehicle speed is equal to or greater than a predetermined speed.

4. The control device for a coupled vehicle according to claim 2, wherein the execution conditions for the notification process include a condition that the absolute value of the steering angle is greater than or equal to a predetermined angle.

5. The system is configured to perform a towing information acquisition process to obtain information regarding whether or not the tractor is in a state of towing the trailer. The control device for a coupled vehicle according to claim 2, wherein the execution conditions for the notification process include a condition that the tractor is in a state of towing the trailer.

6. The control device for a coupled vehicle according to claim 2, configured to perform a modification process to change the threshold according to the vehicle speed.

7. The system is configured to perform a slowdown process when executing the aforementioned notification process. The aforementioned blunting process is a process that operates the target object according to the value of an operation input variable that is determined to blunt the yaw response to a turning instruction operation. The object of the operation is at least one of the three systems: the steering system, the drive system, and the braking system. The control device for a coupled vehicle according to claim 2, wherein the operation input variable is a variable that determines the input signal to the object to be operated.

8. It is configured to perform towing information acquisition processing and towing processing, The towing information acquisition process is a process for acquiring information regarding whether or not the tractor is in a state of towing the trailer. The towing process is a process in which, when the trailer is being towed, the target of the operation is operated according to the value of the operation input variable which is set to slow down the yaw response to the turning instruction operation compared to when the trailer is not being towed. The control device for a coupled vehicle according to claim 7, wherein the blunting process is a process of operating the target to be operated according to a value of the operation input variable which is determined to be greater in degree than the towing process, in order to blunt the yaw response to the input.

9. The control device for a coupled vehicle according to claim 2, wherein the notification process includes a process of notifying that there is a risk of a sway phenomenon occurring in the trailer by applying vibration to the input section to which the driver makes steering input.

10. The control device for a connected vehicle according to claim 2, wherein the notification process includes a process of notifying that there is a risk of the trailer swaying due to the output of visual or audio information.

11. A steering control method applicable to a combined vehicle comprising a tractor and a trailer towed by the tractor, This includes the execution of the acquisition process and the execution of the notification process. The aforementioned acquisition process is a process for acquiring the value of the steering angle velocity variable, The steering angle velocity variable is a variable that indicates the rate of change of the steering angle of the tractor, The notification process is a process that, when the absolute value of the steering angle velocity variable is greater than or equal to a threshold, notifies that there is a risk of the trailer swaying by operating the notification device. The notification device is an interface for transmitting information to a person, A control method for coupled vehicles, wherein the execution conditions for the notification process include a condition that the sign of the steering angle velocity variable matches the sign of the steering angle.

12. A steering control method applicable to a combined vehicle comprising a tractor and a trailer towed by the tractor, This includes the execution of the acquisition process and the execution of the notification process. The aforementioned acquisition process is a process for acquiring the value of the steering angle velocity variable, The steering angle velocity variable is a variable that indicates the rate of change of the steering angle of the tractor, The notification process is a process that, when the absolute value of the steering angle velocity variable is greater than or equal to a threshold, notifies that there is a risk of the trailer swaying by operating the notification device. The notification device is an interface for transmitting information to a person, It is configured to execute a trailer information acquisition process to acquire trailer information, The trailer information includes at least one of the following three items: the position of the trailer's center of gravity, the total weight of the trailer, and the length of the trailer. A control method for articulated vehicles configured to perform a modification process to change the threshold value according to the trailer information.

13. A steering control program applied to a combined vehicle comprising a tractor and a trailer towed by the tractor, This includes instructions to cause the computer to perform acquisition and notification processes, The aforementioned acquisition process is a process for acquiring the value of the steering angle velocity variable, The steering angle velocity variable is a variable that indicates the rate of change of the steering angle of the tractor, The notification process is a process that, when the absolute value of the steering angle velocity variable is greater than or equal to a threshold, notifies that there is a risk of the trailer swaying by operating the notification device. The notification device is an interface for transmitting information to a person, A control program for a coupled vehicle, in which the execution conditions for the notification process include a condition that the sign of the steering angle velocity variable matches the sign of the steering angle.

14. A steering control program applied to a combined vehicle comprising a tractor and a trailer towed by the tractor, This includes instructions to cause the computer to perform acquisition and notification processes, The aforementioned acquisition process is a process for acquiring the value of the steering angle velocity variable, The steering angle velocity variable is a variable that indicates the rate of change of the steering angle of the tractor, The notification process is a process that, when the absolute value of the steering angle velocity variable is greater than or equal to a threshold, notifies that there is a risk of the trailer swaying by operating the notification device. The notification device is an interface for transmitting information to a person, It is configured to execute a trailer information acquisition process to acquire trailer information, The trailer information includes at least one of the following three items: the position of the trailer's center of gravity, the total weight of the trailer, and the length of the trailer. A control program for a coupling vehicle configured to perform a modification process to change the threshold value according to the trailer information.