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

Abstract

This articulated vehicle (10) comprises a tractor (20) and a trailer (30) that is towed by the tractor. A control device (70) is configured so as to perform an open-loop operation quantity calculation process, a closed-loop operation quantity calculation process, an operation process, and a correction process. The open-loop operation quantity calculation process is a process for calculating an open-loop operation quantity, which is an operation quantity for open-loop control in which a prescribed condition quantity of the articulated vehicle is a control quantity. The closed-loop operation quantity calculation process is a process for calculating a closed-loop operation quantity, which is an operation quantity for closed-loop control in which the prescribed condition quantity is a control quantity. The operation process is a process for operating an actuator of the tractor in accordance with both the open-loop operation quantity and the closed-loop operation quantity. The correction process is a process for correcting the open-loop operation quantity calculation process when the size of the operation quantity for the closed-loop control is greater than or equal to a prescribed size.

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 articulated vehicles. This control device appropriately sets emergency braking by estimating the lateral force that can be generated at each wheel depending on road conditions, etc.

[0003] US Patent Application Publication No. 2018319382

[0004] Meanwhile, when designing controllers for articulated vehicles, models of the articulated vehicles tend to be used. The control performance of the controller depends on the accuracy of the model. If the control performance of the designed controller is poor, it will result in a decrease in ride comfort and drivability.

[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 open-loop manipulated variable calculation process, a closed-loop manipulated variable calculation process, an operation process, and a correction process. The open-loop manipulated variable calculation process is a process for calculating an open-loop manipulated variable that is an operation variable for open-loop control in which a predetermined state variable of the articulated vehicle is a control variable. The closed-loop manipulated variable calculation process is a process for calculating a closed-loop manipulated variable that is an operation variable for closed-loop control in which the predetermined state variable is a control variable. The operation process is a process for operating an actuator of the tractor in accordance with both the open-loop manipulated variable and the closed-loop manipulated variable. The correction process is a process for correcting the open-loop manipulated variable calculation process when the magnitude of the operation variable of the closed-loop control is equal to or greater than a predetermined value.

[0006] Another aspect of the present embodiment 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 open-loop manipulated variable calculation process, executing a closed-loop manipulated variable calculation process, executing an operation process, and executing a correction process. The open-loop manipulated variable calculation process is a process for calculating an open-loop manipulated variable that is a manipulated variable for open-loop control in which a predetermined state variable of the articulated vehicle is a control variable. The closed-loop manipulated variable calculation process is a process for calculating a closed-loop manipulated variable that is a manipulated variable for closed-loop control in which the predetermined state variable is a control variable. The operation process is a process for operating an actuator of the tractor in accordance with both the open-loop manipulated variable and the closed-loop manipulated variable. The correction process is a process for correcting the open-loop manipulated variable calculation process when the magnitude of the manipulated variable of the closed-loop control is equal to or greater than a predetermined value.

[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 causes a computer to execute an open-loop manipulated variable calculation process, a closed-loop manipulated variable calculation process, an operation process, and a correction process. The open-loop manipulated variable calculation process is a process for calculating an open-loop manipulated variable that is a manipulated variable for open-loop control in which a predetermined state variable of the articulated vehicle is a control variable. The closed-loop manipulated variable calculation process is a process for calculating a closed-loop manipulated variable that is a manipulated variable for closed-loop control in which the predetermined state variable is a control variable. The operation process is a process for operating an actuator of the tractor in accordance with both the open-loop manipulated variable and the closed-loop manipulated variable. The correction process is a process for correcting the open-loop manipulated variable calculation process when the magnitude of the manipulated variable of the closed-loop control is equal to or greater than a predetermined value.

[0008] FIG. 14 is a perspective view showing the configuration of an articulated vehicle according to a first embodiment. FIG. 15 is a diagram showing the configuration of a control system provided in the articulated vehicle shown in FIG. 1. FIG. 16 is a block diagram showing the processing executed by a control device provided in the control system shown in FIG. 2. FIG. 17 is a diagram showing a model of the articulated vehicle according to the same embodiment. FIG. 18 is a flowchart showing the procedure of processing executed by a control device provided in the control system shown in FIG. 2. FIG. 19 is a flowchart showing the procedure of processing executed by a control device provided in the control system shown in FIG. 2. FIG. 20 is a time chart showing the effect of the same embodiment. FIG. 21 is a flowchart showing the procedure of processing executed by a control device according to a second embodiment. FIG. 22 is a flowchart showing the procedure of processing executed by a control device according to the same embodiment. FIG. 23 is a flowchart showing the procedure of processing executed by a control device according to a third embodiment. FIG. 24 is a diagram showing the procedure of processing executed by a control device according to the same embodiment. FIG. 25 is a diagram showing the configuration of a control system according to a fourth embodiment. FIG. 16 is a block diagram showing the process executed by a control device provided in the control system shown in FIG. 13. FIG. 27 is a block diagram showing the process executed by a control device according to a fifth embodiment. FIG. 28 is a flowchart showing the procedure of processing executed by a control device according to a sixth 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 30. Trailer 30 has wheels 32. Wheels 32 include two wheels, a right wheel and a left wheel. Note that by including left and right front wheels and left and right rear wheels, trailer 30 may have a total of four wheels.

[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 included in the combination vehicle 10. As shown in Figure 2, the tractor 20 is equipped with a steering system 50. The steering system 50 includes a steering wheel 52 and the front wheels 22 as steered wheels. A reaction force is applied to the steering wheel 52 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] On the other hand, power is applied to the front wheels 22 from a front wheel steering motor 60. The output voltage of an inverter 62 is applied to the terminals of the front wheel steering motor 60. The steering control device 70 includes a PU 72 and a storage device 74. The PU 72 is a processing unit that executes software processing. The PU 72 may be, for example, a CPU, a GPU, or the like. The PU 72 controls the controlled object of the steering control device 70 by executing a program stored in the storage device 74.

[0013] The control object of the steering control device 70 is the steering wheel 52. Here, the control amount of the control object is the reaction force. The steering control device 70 operates the inverter 56 to control the reaction force. The control object of the steering control device 70 is the front wheels 22. Here, the control amount of the control object is the steering angle of the front wheels 22. The steering angle is the turning angle of the tires. The steering control device 70 operates the inverter 62 to control the steering angle of the front wheels 22.

[0014] To control the controlled variable, the steering control device 70 refers to the steering torque Th detected by the torque sensor 80. The steering torque Th is the torque input to the steering wheel 52. To control the controlled variable, the steering control device 70 also refers to the rotation angle θmh of the reaction force motor 54 detected by the rotation angle sensor 82. To control the controlled variable, the steering control device 70 also refers to the rotation angle θmf of the front wheel steering motor 60 detected by the rotation angle sensor 84.

[0015] The tractor 20 includes a drive system 86. The drive system 86 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 90. The braking system 90 includes a braking control device 91 and a brake actuator 96. The brake actuator 96 is configured to apply braking force to the front wheels 22 and rear wheels 24 of the tractor 20. The braking control device 91 includes a PU 92 and a storage device 94. The PU 92 is a processing unit that executes software processing. The PU 92 may be, for example, a CPU, a GPU, or the like. The PU 92 controls the controlled object of the braking control device 91 by executing a program stored in the storage device 94.

[0016] The control targets of the braking control device 91 are the front wheels 22 and the rear wheels 24. The braking control device 91 operates a brake actuator 96 to control the control amount of the control target. The brake actuator 96 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. Note that the device that decelerates the rotation of the wheels by converting into electrical energy may be shared with the rotating electric machine of the drivetrain 86.

[0017] The tractor 20 is equipped with an ADASECU 100. The ADASECU 100 is equipped with a PU 102 and a storage device 104. The PU 102 is a processing unit that executes software processing. The PU 102 may be, for example, a CPU or a GPU. The PU 102 controls the control object of the ADASECU 100 by executing a program stored in the storage device 104. The control object of the ADASECU 100 is the combination vehicle 10. Here, the control amount is a variable that indicates the behavior of the vehicle. The ADASECU 100 operates the steering system 50, the drive system 86, and the braking system 90 to control the control amount.

[0018] The drive system 86 may include a drive control device that controls an internal combustion engine and a rotating electric machine. In this case, "the ADASECU 100 operates the drive system 86" means that the ADASECU 100 outputs a command signal to the drive control device. Furthermore, "the ADASECU 100 operates the braking system 90" means that the ADASECU 100 outputs a command signal to the braking control device 91. Furthermore, "the ADASECU 100 operates the steering system 50" means that the ADASECU 100 outputs a command signal to the steering control device 70.

[0019] The combination vehicle 10 is equipped with a vehicle speed sensor 112 that detects vehicle speed V. The combination vehicle 10 is equipped with a tractor-side yaw rate sensor 114 that detects tractor yaw rate γ. The combination vehicle 10 is equipped with a trailer-side yaw rate sensor 116 that detects trailer yaw rate γt.

[0020] "Control of Steering Control Device" Fig. 3 shows the processing executed by the steering control device 70. The processing shown in Fig. 3 is realized by the PU 72 repeatedly executing a program stored in the storage device 74, for example, at a predetermined interval.

[0021] The target front wheel steering angle setting process M10 is a process for setting a target front wheel steering angle δf*0, which is a target value for the steering angle of the front wheels 22 of the tractor 20, based on the steering angle θh and the vehicle speed V as input variables. The steering angle θh is the rotation angle of the steering wheel 52. The steering angle θh is calculated by the PU 72 based on the rotation angle θmh as an input variable.

[0022] The target yaw rate setting process M20 is a process for setting a target tractor yaw rate γ*, which is a target value for the tractor yaw rate γ, based on the input variables of the steering angle θh and the vehicle speed V. As an example, the target tractor yaw rate γ* is set to a yaw rate that is expected to occur in the tractor 20 when the tractor 20 is not towing the trailer 30. This setting is intended to assist the combination vehicle 10 in changing lanes, etc.

[0023] The open-loop manipulated variable calculation process M22 is a process for calculating an open-loop manipulated variable Mff, which is a manipulated variable for open-loop control in which the tractor yaw rate γ is the controlled variable, based on the target tractor yaw rate γ* as an input variable. The open-loop manipulated variable Mff is a correction amount for the target front wheel steering angle δf*0 that is required to bring the yaw rate of the tractor 20 closer to the target tractor yaw rate γ*. More specifically, the open-loop manipulated variable calculation process M22 is a process for calculating the open-loop manipulated variable Mff using model variables that define the model of the combination vehicle 10 shown in FIG. 4.

[0024] The model shown in Figure 4 has one front wheel C0 corresponding to the pair of front wheels 22 of the tractor 20, and one rear wheel B0 corresponding to the pair of rear wheels 24 of the tractor 20. In other words, a two-wheel model is used for the tractor 20. Also, there is one wheel B1 corresponding to the pair of wheels 32 of the trailer 30. The angle between the line defined by the front wheel C0 and hitch point C1 and the line defined by the hitch point C1 and wheel B1 is the hitch angle θ. The hitch point C1 corresponds to the axle 42 in Figure 1.

[0025] The tractor center-of-gravity front wheel distance lf is the distance between the front wheels C0 of the tractor 20 and the center of gravity of the tractor 20. The tractor center-of-gravity rear wheel distance lr is the distance between the rear wheels B0 of the tractor 20 and the center of gravity of the tractor 20. The tractor center-of-gravity hitch point distance lh is the distance between the center of gravity of the tractor 20 and the hitch point C1. The trailer center-of-gravity hitch point distance lft is the distance between the center of gravity of the trailer 30 and the hitch point C1. The trailer center-of-gravity rear wheel distance lrt is the distance between the center of gravity of the trailer 30 and the wheel B1. The tractor front wheel lateral force Sf is the lateral force applied to the front wheels C0. The tractor rear wheel lateral force Sr is the lateral force applied to the rear wheels B0. In addition, in this model, the turning angle of the tires of the front wheels C0 is set to the front wheel steering angle δf. In addition, the turning angle of the tires of the rear wheels B0 is set to the rear wheel steering angle δr. However, in this embodiment, the rear wheel steering angle δr is always considered to be 0. Also, in this model, the longitudinal movement speed of the center of gravity of the tractor 20 is considered to be the vehicle speed V of the combination vehicle 10. The tractor lateral speed vy indicates the lateral speed of the center of gravity of the tractor 20. The trailer lateral speed vyt indicates the lateral speed of the center of gravity of the trailer 30. The tractor lateral wind force W indicates the force applied by the lateral wind to the tractor 20. The trailer lateral wind force Wt indicates the force applied by the lateral wind to the trailer 30.

[0026] The open-loop operation amount calculation process M22 is a process for calculating a target tractor yaw rate γ* based on the following equation of motion for the model shown in FIG. m・V・(dβ / dt+γ)=Sf+Sr−F+W…(c1) Iz・dγ / dt=lf・Sf−lr・Sr+lh・F+lw・W+Mz…(c2) mt・V・(dβt / dt+γt)=Sfr+Ft+Wt…(c3) Izt・dγt / dt=lft・Ft−lrt・Srt+lwt・Wt+Mzt…(c4) Sf=Cf・{δf−(vy+lf・γ) / V}…(c5) Sγ=Cr・{δr−(vy−lr・γ) / V}…(c6) Srt=-Crt・(vyt-lrt・γt) / V…(c7) Here, the sideslip angle β is the sideslip angle of the tractor 20. The sideslip angle βt is the sideslip angle of the trailer 30. The tractor hitch force F is the force applied to the tractor 20 at the hitch point C1. The trailer hitch force Ft is the force applied to the trailer 30 at the hitch point C1. The tractor moment of inertia Iz is the moment of inertia of the tractor 20 in the vertical direction. The trailer moment of inertia Izt is the moment of inertia of the trailer 30 in the vertical direction. The vertical direction refers to the direction perpendicular to the front, rear, left, and right directions of the combination vehicle 10. The tractor braking moment Mz is the moment generated in the tractor 20 by the brake actuator 96. The trailer braking moment Mzt is the moment applied to the trailer 30 when the trailer 30 is equipped with a brake actuator. However, in this embodiment, the trailer braking moment Mzt is zero. The tractor crosswind center lw is the distance between the center at which a crosswind is applied to the tractor 20 and the center of gravity of the tractor 20. The trailer crosswind center lwt is the distance between the center at which a crosswind is applied to the trailer 30 and the center of gravity of the trailer 30. The tractor front wheel cornering coefficient Cf is the cornering coefficient of the front wheels C0 of the tractor 20. The tractor rear wheel cornering coefficient Cr is the cornering coefficient of the rear wheels B0 of the tractor 20.The trailer cornering coefficient Crt is the cornering coefficient of the trailer wheel B1.

[0027] The above formula (c1) represents the lateral movement of the tractor 20. The above formula (c2) represents the rotational movement of the tractor 20. The above formula (c3) represents the lateral movement of the trailer 30. The above formula (c4) represents the rotational movement of the trailer 30.

[0028] The open-loop manipulated variable calculation process M22 includes a process of substituting the target tractor yaw rate γ* for the tractor yaw rate γ. The open-loop manipulated variable calculation process M22 includes a process of substituting the open-loop manipulated variable Mff with a value obtained by subtracting the target front wheel steering angle δf*0 from the front wheel steering angle δf obtained by algebraically solving the simultaneous equations of the above equations (c1) to (c7). The unknowns in the simultaneous equations of the above equations (c1) to (c7) are the front wheel steering angle δf, the tractor front wheel lateral force Sf, the tractor rear wheel lateral force Sr, the slip angles β and βt, the tractor hitch force F, and the trailer hitch force Ft. When calculating the value of the front wheel steering angle δf, the terms in the simultaneous equations (c1) to (c7) above, including the tractor crosswind center lw, the trailer crosswind center lwt, the tractor crosswind force W, and the trailer crosswind force Wt, may be assumed to be zero. Alternatively, the tractor crosswind center lw, the trailer crosswind center lwt, the tractor crosswind force W, and the trailer crosswind force Wt may be estimated by, for example, obtaining weather information such as wind volume and wind direction from outside the articulated vehicle 10. The tractor center-of-gravity-to-rear wheel distance lr, the tractor center-of-gravity-to-hitch point distance lh, the trailer center-of-gravity-to-hitch point distance lft, and the trailer center-of-gravity-to-rear wheel distance lrt are pre-stored in the storage device 74. The tractor moment of inertia Iz and the trailer moment of inertia Izt are also stored in the storage device 74. The PU 72 uses the detected value as the trailer yaw rate γt in the simultaneous equations (c1) to (c7) above. The PU 72 also calculates the tractor lateral velocity vy and the trailer lateral velocity vyt based on the vehicle speed V, slip angles β, βt, etc.

[0029] The deviation calculation process M24 calculates a deviation Δγ, which is a value obtained by subtracting the tractor yaw rate γ from the target tractor yaw rate γ*. The closed-loop manipulated variable calculation process M26 calculates, based on the deviation Δγ as an input variable, a closed-loop manipulated variable Mfb, which is a manipulated variable for closed-loop control in which the tractor yaw rate γ is a controlled variable and the target tractor yaw rate γ* is a target value for the controlled variable.

[0030] The operation amount calculation process M28 is a process of substituting the sum of the open-loop operation amount Mff and the closed-loop operation amount Mfb for the correction amount Δf. The turning angle correction process M30 is a process of substituting the value obtained by adding the correction amount Δf to the target front wheel turning angle δf*0 for the target front wheel turning angle δf*.

[0031] The operation signal generation process M32 as an operation process is a process that generates an operation signal MSf for the inverter 62 based on the target front wheel steering angle δf* as an input variable. The operation signal MSf controls the torque of the front wheel steering motor 60 so that the front wheel steering angle δf approaches the target front wheel steering angle δf*.

[0032] "Regarding Acquisition of Model Variables" The trailer 30 towed by the tractor 20 can be freely changed by the driver. As a result, the specifications of the trailer 30 are subject to change. Therefore, in this embodiment, model information related to the trailer 30 is acquired by input from outside the combination vehicle 10.

[0033] Figure 5 shows the procedure for processing to acquire model variables of the trailer 30. The series of processes shown in Figure 5 is realized by the PU 102 repeatedly executing a program stored in the storage device 104 of the ADASECU 100, for example, at a predetermined interval. Note that, hereinafter, the step numbers of each process are represented by numbers preceded by "S."

[0034] In the series of processes shown in Fig. 5, the PU 102 first determines whether values ​​of model variables defining the trailer 30 have been input by an input operation to the user interface 130 shown in Fig. 2 (S10). In the process of S10, as an example, the model variables are variables indicating the trailer weight mt and center of gravity information of the trailer 30. The variables indicating the center of gravity information of the trailer 30 are the distance lft between the trailer center of gravity and the hitch point, and the distance lrt between the trailer center of gravity and the rear wheels.

[0035] When the PU 102 determines that the values ​​of the model variables have been input (S10: YES), it stores the trailer weight mt, the trailer center-to-hitch point distance lft, and the trailer center-to-rear wheel distance lrt in the storage device 104 (S12).

[0036] 5 when the processing of S12 is completed or when a negative determination is made in the processing of S10. When the processing of S12 is being performed, the PU 72 acquires the trailer weight mt, the trailer center-of-gravity hitch point distance lft, and the trailer center-of-gravity rear wheel distance lrt stored in the storage device 104 from the ADASECU 100 and stores them in the storage device 74. On the other hand, when the processing of S12 is not completed, the open-loop operation amount calculation processing M22 includes a process of reading out default values ​​previously stored in the storage device 74 as the trailer weight mt, the trailer center-of-gravity hitch point distance lft, and the trailer center-of-gravity rear wheel distance lrt.

[0037] "Updating Trailer Cornering Coefficient" The open-loop manipulated variable calculation process M22 includes a process of calculating the open-loop manipulated variable Mff using a default value as the trailer cornering coefficient Crt that is pre-stored in the storage device 74. The trailer cornering coefficient Crt changes not only depending on the specifications of the trailer 30 but also due to aging of the wheels 32 of the trailer 30. Therefore, in this embodiment, the trailer cornering coefficient Crt used by the open-loop manipulated variable calculation process M22 is updated by estimating the trailer cornering coefficient Crt.

[0038] The process for updating the trailer cornering coefficient Crt is shown in Figure 6. The series of processes shown in Figure 6 is realized by the PU 72 repeatedly executing a program stored in the storage device 74, for example, at predetermined intervals.

[0039] 6 , the PU 72 first determines whether the tractor 20 is in a state to tow the trailer 30 (S20). In other words, the PU 72 determines whether the trailer 30 is coupled to the rear of the tractor 20 via the ball joint 40. The processing of S20 may be, for example, processing in which the PU 72 determines whether there is a history in the storage device 74 of information indicating that the driver has coupled the trailer 30 to the tractor 20 through an input operation on the user interface 130. Alternatively, for example, the processing of S20 may be processing executed using an image captured by a camera provided at the rear of the tractor 20.

[0040] When the PU 72 determines that the tractor 20 is in a towing state (YES in S20), the PU 72 determines whether or not a load is loaded on the trailer 30 (S22). The processing of S22 may be, for example, processing in which the PU 72 determines whether or not there is a history in the storage device 74 of the driver inputting information indicating that a load has been loaded on the trailer 30 through an input operation on the user interface 130. Alternatively, for example, the processing of S22 may be processing executed using an image captured by a camera provided at the rear of the tractor 20.

[0041] If the PU 72 determines that no cargo is loaded (S22: YES), it determines whether the combination vehicle 10 is traveling (S24). If the PU 72 determines that the combination vehicle 10 is traveling (S24: YES), it determines whether the absolute value of the closed-loop operation amount Mfb is equal to or greater than a threshold value Mfbth (S26). This process determines whether the value of the trailer cornering coefficient Crt used in the open-loop operation amount calculation process M22 is likely to deviate significantly from the actual value. In other words, if the magnitude of the closed-loop operation amount Mfb is equal to or greater than a predetermined value, there is a possibility that the open-loop operation amount Mff calculated by the open-loop operation amount calculation process M22 is likely to deviate significantly from an appropriate value. On the other hand, the open-loop operation amount calculation process M22 is a process for calculating the open-loop operation amount Mff using the trailer cornering coefficient Crt. Therefore, when the magnitude of the closed-loop operation amount Mfb is equal to or greater than a predetermined value, the value of the trailer cornering coefficient Crt may deviate significantly from the actual value.

[0042] When the PU 72 determines that the absolute value of the closed-loop control input Mfb is equal to or greater than the threshold value Mfbth (YES in S26), the PU 72 acquires the closed-loop control input Mfb (S28). Then, the PU 28 calculates a correction amount ΔCrt for the trailer cornering coefficient Crt based on the closed-loop control input Mfb as an input variable (S30). The correction amount ΔCrt is a value for correcting the trailer cornering coefficient Crt so as to reduce the magnitude of the closed-loop control input Mfb.

[0043] The process of S30 may be a process in which the PU 72 performs map calculation to calculate the correction amount ΔCrt with map data stored in the storage device 74. Here, the map data is data in which the closed-loop manipulated variable Mfb is an input variable and the correction amount ΔCrt is an output variable. Alternatively, the process of S30 may be a process in which the correction amount ΔCrt is calculated in accordance with the value of an output variable of a proportional controller or the like in which the closed-loop manipulated variable Mfb is an input variable.

[0044] The process of S30 may be a process in which the input variables include the vehicle speed V, etc., in addition to the closed-loop manipulated variable Mfb. In this case, the process of S28 may include a process for acquiring the vehicle speed V, etc. Furthermore, when a map calculation is performed in the process of S30, the map data may be data in which the closed-loop manipulated variable Mfb, the vehicle speed V, etc. are input variables and the correction amount ΔCrt is an output variable. Furthermore, when the correction amount ΔCrt is calculated using a proportional controller, etc., in the process of S30, a process may be configured in which the proportional gain is changed in accordance with the vehicle speed V, etc.

[0045] 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.

[0046] The PU 72 performs guard processing to keep the magnitude of the correction amount ΔCrt equal to or less than the upper limit value (S32).The PU 72 then adds the guarded correction amount ΔCrt to the trailer cornering coefficient Crt and assigns the result to the trailer cornering coefficient Crt (S34).

[0047] When the PU 72 completes the process of S34 or when a negative determination is made in the processes of S20 to S26, the PU 72 temporarily ends the series of processes shown in Fig. 6. The processes of S28 to S34 correspond to the correction process.

[0048] "Updating trailer moment of inertia and center of gravity variables" The open-loop manipulated variable calculation process M22 includes a process for calculating the open-loop manipulated variable Mff using the trailer moment of inertia Izt and center of gravity information of the trailer 30. The trailer moment of inertia Izt and center of gravity information of the trailer 30 change not only depending on the specifications of the trailer 30 but also on the state of the load on the trailer 30. Therefore, in this embodiment, the trailer moment of inertia Izt and center of gravity information of the trailer 30 used by the open-loop manipulated variable calculation process M22 are updated by estimating the trailer moment of inertia Izt and center of gravity information of the trailer 30.

[0049] 7 shows the procedure for processing to update the trailer moment of inertia Izt and the center of gravity information of the trailer 30. The series of processes shown in FIG. 7 is realized by the PU 72 repeatedly executing a program stored in the storage device 74, for example, at a predetermined interval.

[0050] In the series of processes shown in Figure 7, the PU 72 first determines whether the tractor 20 is towing the trailer 30 (S40), similar to the process of S20 in Figure 6. If the PU 72 determines that the trailer 30 is towing (S40: YES), it determines whether the trailer 30 is loaded (S42), similar to the process of S22 in Figure 6. If the PU 72 determines that the trailer 30 is loaded (S42: YES), it determines whether the combination vehicle 10 is traveling (S44). If the PU 72 determines that the combination vehicle 10 is traveling (S44: YES), it determines whether the absolute value of the closed-loop operation amount Mfb is equal to or greater than a threshold value Mfbth (S46). This process determines whether at least one of the trailer moment of inertia Izt and the center of gravity information of the trailer 30 significantly deviates from its actual value.

[0051] When the PU 72 determines that the absolute value of the closed-loop manipulated variable Mfb is equal to or greater than the threshold value Mfbth (S46: YES), the PU 72 acquires the closed-loop manipulated variable Mfb (S48). Then, the PU 72 calculates a correction amount ΔIz for the trailer moment of inertia Izt and a correction amount for the center-of-gravity information of the trailer 30 based on the closed-loop manipulated variable Mfb as an input variable (S50). The correction amount ΔIz is a value for correcting the trailer moment of inertia Izt so as to reduce the magnitude of the closed-loop manipulated variable Mfb. The center-of-gravity information correction amount ΔIft is a value for correcting the trailer center-of-gravity hitch point distance lft so as to reduce the magnitude of the closed-loop manipulated variable Mfb. The center-of-gravity information correction amount ΔIrt is a value for correcting the trailer center-of-gravity rear wheel distance lrt so as to reduce the magnitude of the closed-loop manipulated variable Mfb.

[0052] The process of S50 may be a process in which the PU 72 performs map calculations to determine the correction amounts ΔIft, ΔIft, and ΔIrt with map data stored in the storage device 74. Here, the map data is data in which the closed-loop manipulated variable Mfb is an input variable and the correction amounts ΔIft, ΔIft, and ΔIrt are output variables. Alternatively, the process of S50 may be a process in which the correction amounts ΔIft, ΔIft, and ΔIrt are calculated in accordance with the value of an output variable of a proportional controller or the like in which the closed-loop manipulated variable Mfb is an input variable.

[0053] The process of S50 may be a process in which the input variables include the vehicle speed V, etc., in addition to the closed-loop manipulated variable Mfb. In this case, the process of S48 may include a process for acquiring the vehicle speed V, etc. Furthermore, when a map calculation is performed in the process of S50, the map data may be data in which the closed-loop manipulated variable Mfb, the vehicle speed V, etc. are input variables and the correction amounts ΔIft, ΔIft, ΔIrt are output variables. Furthermore, when the correction amounts ΔIft, ΔIft, ΔIrt are calculated using a proportional controller or the like in the process of S50, a process may be configured in which the proportional gain is changed in accordance with the vehicle speed V, etc.

[0054] The PU 72 performs guard processing so that the magnitudes of the correction amounts ΔIft, ΔIft, and ΔIrt are equal to or less than the upper limit (S52). The PU 72 then updates the trailer moment of inertia Izt and values ​​indicating the center of gravity information of the trailer 30 (S54). That is, the PU 72 adds the guard-processed correction amount ΔIft to the trailer moment of inertia Izt and substitutes the result for the trailer moment of inertia Izt. The PU 72 also adds the guard-processed correction amount ΔIft to the trailer center-of-gravity-to-hitch point distance lft and substitutes the result for the trailer center-of-gravity-to-hitch point distance lft. The PU 72 also adds the guard-processed correction amount ΔIrt to the trailer center-of-gravity-to-rear wheel distance lrt and substitutes the result for the trailer center-of-gravity-to-rear wheel distance lrt.

[0055] When the PU 72 completes the process of S54 or when a negative determination is made in the processes of S40 to S46, the PU 72 temporarily ends the series of processes shown in Fig. 7. The processes of S48 to S54 correspond to the correction process.

[0056] "Functions and Effects of the Present Embodiment" The upper part of Figure 8 illustrates an ideal trajectory when the combination vehicle 10 changes lanes. The PU 72 sets the target tractor yaw rate γ* to the value of the yaw rate of the tractor 20 that is expected when the trailer 30 is not coupled to the tractor 20, in accordance with the steering angle θh and the vehicle speed V. This allows the driver to change lanes of the combination vehicle 10 with the same ease as driving a normal vehicle. Here, the PU 72 calculates the open-loop manipulated variable Mff using the value of the model variable based on the target tractor yaw rate γ*. Therefore, if the value of the model variable deviates from the actual value, the controllability of the tractor yaw rate γ using the open-loop manipulated variable Mff decreases. Therefore, if the magnitude of the closed-loop manipulated variable Mfb is equal to or greater than a predetermined value, the PU 72 updates the value of the model variable.

[0057] The lower part of Fig. 8 illustrates the transition of the tractor yaw rate γ during the lane change illustrated in the upper part of Fig. 8. In Fig. 8, the dashed line indicates the transition of the target tractor yaw rate γ*. In Fig. 8, the solid line indicates the transition of the actual tractor yaw rate γ after the model variable values ​​have been updated. The dashed line in Fig. 8 indicates the transition of the actual tractor yaw rate γ before the model variable has been updated.

[0058] As shown by the dashed and solid lines in Figure 8, by updating the values ​​of the model variables, the controllability of the tractor yaw rate γ is improved. Note that the two-dot chain line in Figure 8 shows an example of how the actual tractor yaw rate γ changes over time when the above control using the tractor yaw rate γ as a controlled variable is not executed. It can be seen that when the tractor 20 is towing the trailer 30, it is difficult to achieve the same driving performance as when the trailer 30 is not being towed by performing the same driving operations as when the trailer 30 is not being towed.

[0059] According to the present embodiment described above, the following further actions and effects can be obtained. (1) The PU 72 updated the trailer cornering coefficient Crt based on the closed-loop manipulated variable Mfb when the trailer 30 is unloaded. When the trailer 30 is loaded, the trailer cornering coefficient Crt is not the only model variable that affects the controllability of the tractor yaw rate γ and whose value is likely to fluctuate. When the trailer 30 is loaded, the model variables that affect the controllability of the tractor yaw rate γ and whose value is likely to fluctuate include the trailer moment of inertia Izt and a variable indicating the center of gravity information of the trailer 30. Therefore, by using the closed-loop manipulated variable Mfb when the trailer 30 is unloaded, the trailer cornering coefficient Crt can be estimated with higher accuracy than when using the closed-loop manipulated variable Mfb when the trailer 30 is loaded.

[0060] (2) The PU 72 updated the trailer moment of inertia Izt and the value indicating the center of gravity information of the trailer 30 based on the closed-loop manipulated variable Mfb when the trailer 30 is loaded. The trailer moment of inertia Izt and the value indicating the center of gravity information of the trailer 30 are likely to fluctuate depending on how the trailer 30 is loaded. Therefore, by using the closed-loop manipulated variable Mfb when the trailer 30 is loaded, it is possible to obtain the trailer moment of inertia Izt and the value indicating the center of gravity information of the trailer 30 that correspond to the state of the load.

[0061] Second Embodiment A second embodiment will be described below with reference to the drawings, focusing on differences from the first embodiment.

[0062] In the first embodiment, the updated model variable values ​​are used in the open-loop manipulated variable calculation process M22. In contrast to this, in the present embodiment, the updated model variable values ​​are also used to detect abnormalities in the combination vehicle 10.

[0063] "Load Abnormality" Figure 9 shows a processing procedure for detecting an abnormality in the state of the load on the trailer 30. The processing shown in Figure 9 is realized by the PU 72 repeatedly executing a program stored in the storage device 74, for example, at a predetermined interval.

[0064] In the series of processes shown in Figure 9, the PU 72 first acquires the trailer moment of inertia Izt, the trailer center-of-gravity hitch point distance Ift, and the trailer center-of-gravity rear wheel distance Irt, which are variables indicating center-of-gravity information (S60). Next, the PU 72 evaluates the center of gravity of the cargo based on the trailer moment of inertia Izt, the trailer center-of-gravity hitch point distance Ift, and the trailer center-of-gravity rear wheel distance Irt, which are input variables (S62). That is, for example, if the center of gravity is located excessively rearward of the trailer 30, the PU 72 evaluates that the cargo is biased toward the rear of the trailer 30. Also, for example, if the trailer moment of inertia Izt is excessively large, the PU 72 evaluates that the cargo is biased toward the edge of the trailer 30.

[0065] The PU 72 determines whether or not there is an abnormality in the cargo position based on the evaluation result of S62 (S64). If the PU 72 determines that there is an abnormality in the cargo position (S64: YES), the PU 72 notifies the driver of this by operating the user interface 130 (S66). For example, if the user interface 130 includes a speaker, the PU 72 may notify the driver of the abnormality in the cargo position by audio information. Alternatively, if the user interface 130 includes a display, the PU 72 may display visual information on the display indicating that there is an abnormality in the cargo position.

[0066] The PU 72 temporarily terminates the series of processes shown in Fig. 9 when it completes the process of S66 or when it makes a negative determination in the process of S64. The process shown in Fig. 9 is particularly effective when the trailer 30 consists only of a loading platform and does not have a roof or the like. The processes of S62 and S64 correspond to abnormality detection processing. The process of S66 corresponds to notification processing.

[0067] "Tire Abnormality" Figure 10 shows a procedure for processing related to detecting an abnormality in the wheels 32 of the trailer 30. The processing shown in Figure 10 is realized by the PU 72 repeatedly executing a program stored in the storage device 74, for example, at a predetermined interval.

[0068] In the series of processes shown in FIG. 10 , the PU 72 first acquires the trailer cornering coefficient Crt (S70). Next, the PU 72 determines whether the trailer cornering coefficient Crt is equal to or less than the threshold value Crtth (S72). If the PU 72 determines that the trailer cornering coefficient Crt is equal to or less than the threshold value Crtth (S72: YES), the PU 72 determines that there is an abnormality in the wheels 32 of the trailer 30 (S74). Then, the PU 72 notifies the driver of the abnormality in the wheels 32 of the trailer 30 by operating the user interface 130 (S76). For example, if the user interface 130 includes a speaker, the PU 72 may notify the driver of the abnormality in the wheels 32 of the trailer 30 by audio information. Alternatively, if the user interface 130 includes a display, the PU 72 may display visual information on the display indicating that there is an abnormality in the wheels 32 of the trailer 30.

[0069] 10 when the process of S76 is completed or when a negative determination is made in the process of S72. The processes of S72 and S74 correspond to the abnormality detection process, and the process of S76 corresponds to the notification process.

[0070] Third Embodiment Hereinafter, a third embodiment will be described with reference to the drawings, focusing on differences from the first embodiment.

[0071] In this embodiment, the amount of correction for the value of the model variable is calculated using the difference between the yaw rate estimated using the value of the model variable and the actual tractor yaw rate γ. "Updating the Trailer Cornering Coefficient" Figure 11 shows the procedure for updating the trailer cornering coefficient Crt. The series of processes shown in Figure 11 are realized by the PU 72 repeatedly executing a program stored in the storage device 74, for example, at a predetermined interval. Note that the same step numbers are used in Figure 11 to designate processes that correspond to those shown in Figure 6.

[0072] In the series of processes shown in FIG. 11 , if the determination in the process of S26 is affirmative, the PU 72 acquires the target front wheel steering angle δf*, vehicle speed V, tractor yaw rate γ, etc. (S28a). Next, the PU 72 calculates an estimated value γe of the tractor yaw rate γ based on the target front wheel steering angle δf*, vehicle speed V, etc. as input variables (S28b). That is, the PU 72 substitutes the target front wheel steering angle δf* for the front wheel steering angle δf in the above equations (c1) to (c7). The PU 72 also substitutes the value acquired in the process of S28a for the vehicle speed V in the above equations (c1) to (c7). The PU 72 then sets one of the unknowns in the simultaneous equations of the above equations (c1) to (c7) as the tractor yaw rate γ. The tractor yaw rate γ calculated in this manner is the estimated value γe.

[0073] The PU 72 calculates a correction amount ΔCrt based on the difference between the tractor yaw rate γ obtained in the process of S28a and the estimated value γe calculated in the process of S28b (S30a). The process of S30a may be a process in which the PU 72 calculates the correction amount ΔCrt using a map while map data is stored in the storage device 74. Here, the map data is data in which the difference is an input variable and the correction amount ΔCrt is an output variable. Alternatively, the process of S30a may be a process in which the correction amount ΔCrt is calculated according to the value of an output variable of a proportional controller or the like in which the difference is an input variable.

[0074] Note that the input variables for the processing of S30a may include the vehicle speed V, etc., in addition to the difference. In this case, when performing map calculations in the processing of S30a, the map data may be data in which the difference and the vehicle speed V, etc., are input variables and the correction amount ΔCrt is an output variable. Furthermore, when the correction amount ΔCrt is calculated using a proportional controller, etc., in the processing of S30a, a process may be constructed in which the proportional gain is changed in accordance with the vehicle speed V, etc.

[0075] When the PU 72 completes the process of S30a, it proceeds to the process of S32. The processes of S28a, S28b, S30a, and S32 to S34 correspond to the correction process. "Updating the Trailer Moment of Inertia and Center of Gravity Variables" Figure 12 shows the procedure for updating the trailer moment of inertia Izt and the center of gravity information of the trailer 30. The process shown in Figure 12 is realized by the PU 72 repeatedly executing a program stored in the storage device 74, for example, at a predetermined interval. The same step numbers are used in Figure 12 to designate processes that correspond to those shown in Figure 7.

[0076] 12, if the determination in S46 is affirmative, the PU 72 acquires the target front wheel steering angle δf*, the vehicle speed V, the tractor yaw rate γ, etc. (S48a). Next, the PU 72 calculates an estimated value γe of the tractor yaw rate γ in the same manner as in S28b, based on the target front wheel steering angle δf*, the vehicle speed V, etc. as input variables (S48b).

[0077] The PU 72 calculates the correction amounts ΔIft, ΔIft, and ΔIrt based on the difference between the tractor yaw rate γ obtained in the process of S48a and the estimated value γe calculated in the process of S48b (S50a).

[0078] The process of S50a may be a process in which the PU 72 calculates the correction amounts ΔIft, ΔIft, and ΔIrt using a map while map data is stored in the storage device 74. Here, the map data is data in which the above-mentioned difference is an input variable and the correction amounts ΔIft, ΔIft, and ΔIrt are output variables. Alternatively, the process of S50a may be a process in which the correction amounts ΔIft, ΔIft, and ΔIrt are calculated according to the value of an output variable of a proportional controller or the like in which the above-mentioned difference is an input variable.

[0079] Note that the input variables for the processing of S50a may include the vehicle speed V, etc., in addition to the difference. In this case, when performing map calculations in the processing of S50a, the map data may be data in which the difference and the vehicle speed V, etc. are input variables and the correction amounts ΔIft, ΔIft, ΔIrt are output variables. Furthermore, when the correction amounts ΔIft, ΔIft, ΔIrt are calculated using a proportional controller, etc., in the processing of S50a, a process may be implemented in which the proportional gain is changed in accordance with the vehicle speed V, etc.

[0080] When the PU 72 completes the process of S50a, it proceeds to the process of S52. Incidentally, the processes of S48a, S48b, S50a, and S52 to S54 correspond to correction processes. <Fourth Embodiment> The fourth embodiment will be described below with reference to the drawings, focusing on the differences from the first embodiment.

[0081] Figure 13 shows some of the members provided in the articulated vehicle 10 according to this embodiment. For convenience, the same reference numerals are used in Figure 13 to designate members corresponding to those shown in Figure 2.

[0082] As shown in Figure 13, in this embodiment, power can be transmitted between the steering wheel 52 and the front wheels 22 via the steering shaft 53. Torque from the assist motor 64 is applied to the steering shaft 53. The output voltage of the inverter 66 is applied to the terminals of the assist motor 64. The rear wheels 24 can be steered by the torque of the rear wheel steering motor 120. The output voltage of the inverter 122 is applied to the terminals of the rear wheel steering motor 120. The steering control device 70 refers to the rotation angle θmf of the assist motor 64 detected by the rotation angle sensor 124. The steering control device 70 refers to the rotation angle θmr of the rear wheel steering motor 120 detected by the rotation angle sensor 126.

[0083] The control targets of the steering control device 70 include the steering shaft 53 and the rear wheels 24. The steering control device 70 operates the inverter 66 to apply an assist torque, which assists the steering of the driver as a controlled variable, to the steering shaft 53. The steering control device 70 operates the inverter 122 to control the rear wheel steering angle δr, which is the steering angle of the rear wheels 24 as a controlled variable.

[0084] Figure 14 shows the processing executed by the steering control device 70. The processing shown in Figure 14 is realized by the PU 72 repeatedly executing a program stored in the storage device 74, for example, at a predetermined interval. Note that in Figure 14, processing corresponding to the processing shown in Figure 3 is denoted by the same reference numerals for convenience.

[0085] The open-loop manipulated variable calculation process M22a is a process for calculating an open-loop manipulated variable Mff, which is a manipulated variable for open-loop control, based on the target tractor yaw rate γ* as an input variable. The open-loop manipulated variable Mff is the rear wheel steering angle δr, which is the steering angle of the rear wheels 24 required to bring the yaw rate of the tractor 20 closer to the target tractor yaw rate γ*. Specifically, the open-loop manipulated variable calculation process M22a is a process for calculating the open-loop manipulated variable Mff using model variables that define the model of the articulated vehicle 10 shown in FIG. 4. The open-loop manipulated variable calculation process M22a is a process for substituting an actual value for the front wheel steering angle δf in the simultaneous equations of the above equations (c1) to (c7), and substituting the result obtained with the rear wheel steering angle δr as an unknown into the open-loop manipulated variable Mff. The actual front wheel steering angle δf is calculated by the PU 72 based on the rotation angle θmf.

[0086] The closed-loop manipulated variable Mfb calculated by the closed-loop manipulated variable calculation process M26a is a correction amount for the open-loop manipulated variable Mff as a manipulated variable of closed-loop control in which the tractor yaw rate γ is the controlled variable.

[0087] The operation amount calculation process M28a is a process of substituting the sum of the open-loop operation amount Mff and the closed-loop operation amount Mfb for the target rear-wheel steering angle δr*. The operation signal generation process M32a as an operation process is a process of generating an operation signal MSr for the inverter 122 based on the target rear-wheel steering angle δr* as an input variable.

[0088] As described above, in this embodiment, the manipulated variable for control in which the tractor yaw rate γ is the controlled variable is the target rear wheel steering angle δr*. The open-loop manipulated variable Mff is calculated using a model based on the target tractor yaw rate γ* as an input variable. When the magnitude of the closed-loop manipulated variable Mfb is equal to or greater than a predetermined value, the value of the model variable is updated.

[0089] Fifth Embodiment Hereinafter, a fifth embodiment will be described with reference to the drawings, focusing on differences from the first embodiment.

[0090] Figure 15 shows the processing executed by the braking control device 91. The processing shown in Figure 15 is realized by the PU 92 repeatedly executing a program stored in the storage device 94, for example, at a predetermined interval. For convenience, the same reference numerals are used in Figure 15 to designate processing that corresponds to the processing shown in Figure 3.

[0091] The open-loop manipulated variable calculation process M22b is a process for calculating an open-loop manipulated variable Mff, which is a vertical moment required to bring the yaw rate of the tractor 20 closer to the target tractor yaw rate γ*, based on the target tractor yaw rate γ* as an input variable. More specifically, the open-loop manipulated variable calculation process M22b is a process for calculating the open-loop manipulated variable Mff using model variables that define the model of the combination vehicle 10 shown in FIG. 4. The open-loop manipulated variable calculation process M22a includes a process for substituting an actual value for the front wheel steering angle δf in the simultaneous equations of the above equations (c1) to (c7) and for setting the tractor brake moment Mz as the calculation target. The open-loop manipulated variable calculation process M22a is a process for substituting the calculated tractor brake moment Mz for the open-loop manipulated variable Mff.

[0092] The closed-loop operation amount calculation process M26b is a process for calculating a closed-loop operation amount Mfb as a correction amount for the tractor brake moment Mz. The operation amount calculation process M28b is a process for substituting the sum of the open-loop operation amount Mff and the closed-loop operation amount Mfb for the target brake moment Mz*.

[0093] The operation signal generation process M32b is a process for generating an operation signal MSb for the brake actuator 96 based on the target brake moment Mz* as an input variable. As described above, in this embodiment, the operation amount for the control in which the tractor yaw rate γ is the controlled variable is the target brake moment Mz*. The open-loop operation amount Mff is then calculated using a model based on the target tractor yaw rate γ* as an input variable. If the magnitude of the closed-loop operation amount Mfb is equal to or greater than a predetermined value, the value of the model variable is updated.

[0094] Sixth Embodiment Hereinafter, the fifth embodiment will be described with reference to the drawings, focusing on the differences from the first embodiment.

[0095] In the first embodiment, the values ​​of the model variables are updated to correct the relationship between the values ​​of the input variables to the open-loop manipulated variable calculation process M22 and the values ​​of the output variables of the open-loop manipulated variable calculation process M22. In this embodiment, when the values ​​of the model variables are updated, the relationship between the values ​​of the input variables to the closed-loop manipulated variable calculation process M26 and the values ​​of the output variables of the closed-loop manipulated variable calculation process M26 is also corrected.

[0096] 16 shows the procedure for correcting the relationship between the input and the output in the closed-loop manipulated variable calculation process M26. The series of processes shown in FIG. 16 is realized by the PU 72 repeatedly executing a program stored in the storage device 74, for example, at a predetermined interval.

[0097] In the series of processes shown in FIG. 16 , the PU 72 first determines whether the value of the model variable has been updated (S80). If the PU 72 determines that the value of the model variable has been updated (S80: YES), the PU 72 calculates a correction amount for the closed-loop gain in the closed-loop manipulated variable calculation process M26 (S82). For example, if the closed-loop manipulated variable calculation process M26 is a process for calculating the closed-loop manipulated variable Mfb based on the output value of a proportional element, the PU 72 may calculate a correction amount for the proportional gain. Alternatively, if the closed-loop manipulated variable calculation process M26 is a process for calculating the closed-loop manipulated variable Mfb based on the output value of an integral element, the PU 72 may calculate a correction amount for the integral gain. Alternatively, if the closed-loop manipulated variable calculation process M26 is a process for calculating the closed-loop manipulated variable Mfb based on the output value of a differential element, the PU 72 may calculate a correction amount for the derivative gain. For example, if the closed-loop manipulated variable calculation process M26 is a process for calculating the closed-loop manipulated variable Mfb based on the output value of the disturbance observer, the PU 72 may calculate a correction amount for the gain of the disturbance observer. The process of S82 is not limited to a process for correcting only one gain. For example, if the closed-loop manipulated variable calculation process M26 is a process for calculating the closed-loop manipulated variable Mfb based on the output value of the proportional element and the output value of the integral element, the PU 72 may calculate a correction amount for the proportional gain and a correction amount for the integral gain. However, in this case, the PU 72 may calculate only one of the correction amount for the proportional gain and the correction amount for the integral gain.

[0098] The PU 72 then corrects the closed-loop gain used in the closed-loop manipulated variable calculation process M26 by the correction amount calculated in the process of S82, thereby updating the closed-loop gain (S84). That is, the PU 72 updates the data in the area of ​​the storage device 74 that stores the closed-loop gain.

[0099] The PU 72 temporarily terminates the series of processes shown in Figure 16 when it completes the process of S84 or when a negative determination is made in the process of S80. In this manner, in this embodiment, the relationship between the values ​​of the input variables to the closed-loop manipulated variable calculation process M26 and the values ​​of the output variables of the closed-loop manipulated variable calculation process M26 is further corrected. This further improves the controllability of the tractor yaw rate γ.

[0100] <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.

[0101] "Regarding the Predetermined State Quantity" The predetermined state quantity as the control variable of the open-loop control and the control variable of the closed-loop control is not limited to the tractor yaw rate γ. The predetermined state quantity may be, for example, the trailer yaw rate γt. Also, for example, the predetermined state quantity may be the hitch angle. Note that it is not essential that there is only one predetermined state quantity. For example, the predetermined state quantity may be the tractor yaw rate γ and the trailer yaw rate γt.

[0102] Regarding the Open-Loop Manipulated Amount Calculation Process: The open-loop manipulated variable calculation process does not necessarily have to be a process of calculating the open-loop manipulated variable Mff by algebraically solving the simultaneous equations (c1) to (c7) above. The open-loop manipulated variable calculation process may include, for example, setting one of the values ​​detected by a sensor, such as the trailer yaw rate γt, as an object to be estimated and substituting various values ​​for variables that were unknown when the algebraic solution was used. In this case, the open-loop manipulated variable calculation process includes a process of searching for the value of the unknown variable so that the value of the variable set as the object to be estimated is closest to the sensor value.

[0103] The open-loop manipulated variable calculation process does not necessarily have to be a process of calculating the open-loop manipulated variable by calculation using the values ​​of the model variables to be corrected by the correction process. For example, the open-loop manipulated variable calculation process may be a process of map-calculating the open-loop manipulated variable by the PU with map data stored in a storage device. Here, the map data is data whose output variables are the open-loop manipulated variables.

[0104] "Use of open-loop manipulated variable Mff" In the above embodiment, the open-loop manipulated variable Mff is used for assistance processing that allows the driver to easily change lanes, etc., but this is not limited to this. For example, the open-loop manipulated variable Mff based on the values ​​of model variables that are successively updated may be used to control the behavior of the combination vehicle 10 regarding parking. Here, control regarding parking is not limited to control by the driver, and may also be automatic driving.

[0105] "Regarding the Correction Process" The values ​​of the model variables to be corrected by the correction process are not limited to the values ​​of the variables exemplified in the above embodiment. The values ​​of the model variables to be corrected by the correction process are not limited to the values ​​of the model variables that define the model of the trailer 30. The values ​​of the model variables to be corrected by the correction process may be, for example, the values ​​of the model variables that define the model of the tractor 20. Specifically, the value of the model variable to be corrected by the correction process may be, for example, the tractor front wheel cornering coefficient Cf. Furthermore, for example, the value of the model variable to be corrected by the correction process may be the tractor rear wheel cornering coefficient Cr.

[0106] The correction process does not necessarily have to be a process of correcting the values ​​of the model variables. For example, as described in the above section "Regarding the Open-Loop Manipulated Variable Calculation Process," in cases where the open-loop manipulated variable is calculated by map calculation, the correction process may be, for example, the following process. That is, the correction process may be a process of calculating a correction amount for the value of the output variable of the map data based on the input variable.

[0107] The closed-loop manipulated variable calculation process to be modified when the model variables are updated is not limited to the closed-loop manipulated variable calculation process M26. The closed-loop manipulated variable calculation process to be modified may be the closed-loop manipulated variable calculation process M26a. Alternatively, the closed-loop manipulated variable calculation process to be modified may be the closed-loop manipulated variable calculation process M26b.

[0108] "Regarding operation processing" The actuator that is the object of operation based on the operation amount of open-loop control is not limited to any one of the actuator that steers the front wheels of the tractor 20, the actuator that steers the rear wheels of the tractor 20, and the brake actuator 96. For example, it may be both the actuator that steers the front wheels of the tractor 20 and the actuator that steers the rear wheels of the tractor 20. The actuator that is the object of operation based on the operation amount of open-loop control is not limited to some of the three, the actuator that steers the front wheels of the tractor 20, the actuator that steers the rear wheels of the tractor 20, and the brake actuator 96. For example, if the thrust generating device of the tractor 20 is equipped with an in-wheel motor, the actuator that is the object of operation based on the operation amount of open-loop control may be the thrust generating device.

[0109] "Method of obtaining values ​​of model variables" Figure 5 shows an example in which the trailer center-to-hitch point distance lft and the trailer center-to-rear wheel distance lrt are obtained by input operations by the user of the combination vehicle, but this is not the only option. For example, they may also be estimated when the combination vehicle 10 is stopped. This estimation may be realized, for example, by using an equation for balance of the moment of the combination vehicle 10 that uses the center of gravity of the tractor 20, the mass of the tractor 20, and the mass of the trailer 30.

[0110] Regarding the Control Device for Articulated Vehicles In the first embodiment, the steering control device 70 executes the processes in Figures 6 and 7, but this is not limiting. For example, the ADASECU 100 may execute the processes in Figures 6 and 7.

[0111] In the second embodiment, the steering control device 70 executes the processes in Figures 9 and 10. However, the present invention is not limited to this. For example, the ADASECU 100 may execute the processes in Figures 9 and 10.

[0112] In the third embodiment, the steering control device 70 executes the processes in Figures 11 and 12. However, the present invention is not limited to this. For example, the ADASECU 100 may execute the processes in Figures 11 and 12.

[0113] In the fourth embodiment, the braking control device 91 executes the correction process, but this is not limiting. For example, the ADASECU 100 may execute the correction process. The control device for the combined vehicles is not limited to one that includes a PU and a storage device and executes software processing. For example, it may include a dedicated hardware circuit, such as an ASIC, that executes at least some of the various processes executed in the above embodiments. That is, the control device may include any of the following processing circuits (a) to (c): (a) A processing circuit that includes a processing device that executes all of the above processes according to a program and a program storage device, such as a storage device, that stores the program. (b) A processing circuit that includes a processing device and program storage device that executes some of the above processes according to a program, and a dedicated hardware circuit that executes the remaining processes. (c) A processing circuit that includes a dedicated hardware circuit that executes all of the above processes. Here, there may be multiple software execution devices that include a processing device and a program storage device, and multiple dedicated hardware circuits.

[0114] Regarding the entity that executes the method for controlling combination vehicles: It is not essential that all of the entities that execute the processes in the above-described embodiment and their modifications be processing circuits mounted on the combination vehicle 10 .

Claims

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 open-loop operation amount calculation processing, closed-loop operation amount calculation processing, operation processing, and correction processing, wherein the open-loop operation amount calculation processing is processing for calculating an open-loop operation amount that is an operation amount for open-loop control in which a predetermined state variable of the articulated vehicle is a control amount, the closed-loop operation amount calculation processing is processing for calculating a closed-loop operation amount that is an operation amount for closed-loop control in which the predetermined state variable is a control amount, the operation processing is processing for operating an actuator of the tractor in accordance with both the open-loop operation amount and the closed-loop operation amount, and the correction processing is processing for correcting the open-loop operation amount calculation processing when the magnitude of the operation amount for the closed-loop control is equal to or greater than a predetermined value.

2. A control device for articulated vehicles as described in claim 1, wherein the open-loop operation amount calculation process is a process for calculating the open-loop operation amount based on calculations using input variables and model variables, the model variables are variables that define a model of the articulated vehicles, and the correction process is a process for correcting the values ​​of the model variables.

3. A control device for articulated vehicles according to claim 2, wherein the correction process is a process for correcting the value of the model variable based on the closed-loop manipulated variable as an input variable.

4. A control device for an articulated vehicle as set forth in claim 2, wherein the correction process includes a process for calculating an estimated value of the controlled variable based on both the open-loop manipulated variable and the closed-loop manipulated variable, and corrects the value of the model variable so as to reduce the magnitude of the difference between the estimated value and the controlled variable.

5. A control device for articulated vehicles according to claim 1, wherein the correction process includes a process for correcting the closed-loop control operation amount calculation process when the magnitude of the closed-loop control operation amount is equal to or greater than a predetermined value.

6. A control device for articulated vehicles according to claim 2, wherein the model variables include at least one of the following three: a trailer center of gravity variable, a trailer cornering coefficient, and a trailer vertical moment of inertia; and the trailer center of gravity variable is a variable indicating the trailer center of gravity.

7. A control device for articulated vehicles as described in claim 6, wherein the model variables include at least one of two variables: a center of gravity variable of the trailer and a vertical moment of inertia of the trailer; and the control device is configured to execute an abnormality detection process and a notification process, wherein the abnormality detection process is a process for detecting an abnormality in the cargo of the trailer based on the value of at least one of the two variables as input variables; and the notification process is a process for notifying a user of the detection of an abnormality in the cargo.

8. A control device for articulated vehicles according to claim 6, wherein the model variables include a cornering coefficient of the trailer, and the control device is configured to execute an abnormality detection process and a notification process, wherein the abnormality detection process is a process for detecting an abnormality in the tires of the trailer based on the cornering coefficient of the trailer as an input variable, and the notification process is a process for notifying a user if an abnormality in the tire is detected.

9. A control method for an articulated vehicle that is applied to an articulated vehicle that includes a tractor and a trailer towed by the tractor, the control method comprising the steps of: executing an open-loop operation amount calculation process; executing a closed-loop operation amount calculation process; executing an operation process; and executing a correction process; wherein the open-loop operation amount calculation process is a process for calculating an open-loop operation amount that is a operation amount for open-loop control in which a predetermined state variable of the articulated vehicle is a control amount; the closed-loop operation amount calculation process is a process for calculating a closed-loop operation amount that is a operation amount for closed-loop control in which the predetermined state variable is a control amount; the operation process is a process for operating an actuator of the tractor in accordance with both the open-loop operation amount and the closed-loop operation amount; and the correction process is a process for correcting the open-loop operation amount calculation process when the magnitude of the operation amount for closed-loop control is equal to or greater than a predetermined value.

10. A control program for an articulated vehicle that is applied to an articulated vehicle that includes a tractor and a trailer towed by the tractor, the control program having instructions for causing a computer to execute open-loop operation amount calculation processing, closed-loop operation amount calculation processing, operation processing, and correction processing, wherein the open-loop operation amount calculation processing is processing for calculating an open-loop operation amount that is an operation amount for open-loop control in which a predetermined state variable of the articulated vehicle is a control amount, the closed-loop operation amount calculation processing is processing for calculating a closed-loop operation amount that is an operation amount for closed-loop control in which the predetermined state variable is a control amount, the operation processing is processing for operating an actuator of the tractor in accordance with both the open-loop operation amount and the closed-loop operation amount, and the correction processing is processing for correcting the open-loop operation amount calculation processing when the magnitude of the operation amount of the closed-loop control is equal to or greater than a predetermined value.

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