Method for providing a manipulated variable of a closed-loop control device, the manipulated variable characterising a drive signal for a steering actuator of a steering system of a vehicle, steering system, and vehicle comprising the steering system
The method enhances steering feel in assisted driving systems by using sub-controllers to adjust the steering actuator based on driver input and vehicle parameters, addressing the unnatural feel of existing systems and improving control performance and stability.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- ROBERT BOSCH GMBH
- Filing Date
- 2025-11-10
- Publication Date
- 2026-05-21
AI Technical Summary
Existing assisted driving systems in vehicles provide high-performance position control but result in an unnatural or dull steering feel for the driver, lacking the naturalness of manual operation.
A method and system that determines a manipulated variable for a control device to adjust the steering actuator, considering driver input and vehicle parameters, using multiple sub-controllers to enhance control performance and stability, thereby improving the steering feel in semi-autonomous modes.
The solution provides a natural and dynamic steering feel by accounting for driver interaction and vehicle conditions, enhancing control performance and stability, resulting in a more pleasant driving experience.
Smart Images
Figure EP2025082517_21052026_PF_FP_ABST
Abstract
Description
[0001] R.413432
[0002] - 1 -
[0003] Description
[0004] title
[0005] Method for providing a control variable of a control device that characterizes a control signal of a steering actuator of a steering system of a vehicle, a steering system and a vehicle comprising the steering system
[0006] State of the art
[0007] The present invention relates to a method for providing a control variable of a control device, which characterizes a control signal of a steering actuator of a steering system of a vehicle, a steering system and a vehicle comprising the steering system.
[0008] Assisted driving functions are typically based on the rotor position of a steering system actuator. This means that a controller considers any discrepancies in this rotor position to determine a target drive torque, which is then applied to the steering system actuator to reduce the difference between the requested and actual rotor positions, thereby maintaining the requested vehicle trajectory. This results in high performance in achieving the requested rotor position and ensures that the position is reached within the required timeframe.Nevertheless, this approach results in an unpleasant steering feel for the driver of the vehicle, which can be described or perceived as dull or artificial, and is not comparable to a natural steering feel in a non-assisted manual operating mode of the vehicle.
[0009] Therefore, a steering system is desirable that has a powerful, high-performance position control and also provides assisted steering. R.413432
[0010] - 2 -
[0011] Provides an operating mode that offers a natural steering feel for a driver or user of the steering system.
[0012] Disclosure of the invention
[0013] This is achieved by a method, a steering system and a vehicle comprising the steering system according to the independent claims.
[0014] The method for providing a manipulated variable to a control device, which characterizes a control signal of a steering actuator of a vehicle's steering system, wherein the vehicle is operated in a semi-autonomous mode, comprises: determining a difference between a setpoint and an actual value of a characteristic parameter that characterizes a direction of travel of the vehicle, in particular a position of a rack of the steering system; determining a first adaptation component depending on an actual hand torque and the difference component by means of a first controller included in the control device; determining a setpoint hand torque depending on the first adaptation component and the difference component; providing the manipulated variable, wherein the manipulated variable is determined depending on the setpoint hand torque and the actual hand torque by a second controller included in the control device.The manipulated variable can, for example, be a drive torque for the steering actuator, which influences the rotor position of the steering actuator and thus the vehicle's direction of travel. In this context, the semi-autonomous operating mode encompasses assisted driving of the vehicle, where driver input is taken into account. Assisted driving includes, for example, a lane keeping assist system. The semi-autonomous operating mode can be classified, for example, as SAE L1, SAE L2, or SAE L2+ according to SAE J3016. In this context, the characteristic parameter describes a parameter of the steering system that has a direct influence on the vehicle's direction of travel. This could, for example, be the position of the rack, which is influenced by a variation in the rotor position of the steering actuator.The rack has a primarily mechanical connection to the vehicle's tracking elements, such as wheels. The vehicle's trajectory is influenced by the movement of these tracking elements. The actual hand torque, for example, describes a torque applied to the steering column of the R.413432.
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[0016] The steering system's torque is measured. The target steering torque, therefore, describes the desired torque at the steering column. The actual steering torque is adjusted to the target torque using the manipulated variable. The actual steering torque is, for example, measured, determined, or provided. The first adaptation step improves the performance or control behavior of the manipulated variable or control signal, making the steering system more dynamic. Furthermore, the actual steering torque is taken into account when determining the adaptation step, which, for example, reflects the driver's influence or interaction with the steering system, thus improving the steering feel and making it more natural.
[0017] In this context, a steering actuator is understood to mean, in particular, an actuator unit, especially an electrically designed one, which has a direct operative connection with the rack and is specifically designed to transmit a steering torque to the rack and thereby influence the vehicle's direction of travel. For example, the steering actuator is designed to provide a steering torque to assist a hand torque applied by the driver at an input device and / or a steering torque for the direct adjustment of the vehicle's wheels, and thereby, in particular, for the automatic and / or autonomous control of the vehicle's direction of travel. For this purpose, the steering actuator may include at least one electric motor.
[0018] Furthermore, a control device shall be understood to mean, in particular, an electrical and / or electronic unit designed to provide control functionality for the operation of the steering actuator and / or the steering system. In the present case, the control device is specifically designed as a hand torque controller and is intended, in particular, at least for controlling the actual hand torque as a function of the target hand torque, wherein the target hand torque corresponds in particular to a reference variable and the actual hand torque to a controlled variable. Moreover, the manipulated variable of the control device corresponds in particular to the control signal of the steering actuator. R.413432
[0019] - 4 -
[0020] It is possible for the first controller to comprise a plurality of sub-controllers, with the plurality of sub-controllers being arranged sequentially, and the initial adaptation component being determined by the plurality of sub-controllers. The plurality of sub-controllers allows for faster response to disturbances and improves the control performance of the first controller. Furthermore, it increases the robustness and stability of the first controller and thus also of the entire steering system.
[0021] The first controller may include a first sub-controller that determines a first manipulated variable, in the form of a dynamic parameter of the characteristic value (in particular, a setpoint speed of the characteristic value, for example, the setpoint speed of the rack), depending on the differential variable. A second sub-controller then determines the adaptation component based on the first manipulated variable. This ensures, for example, a constant deviation between the setpoint and the actual value of the characteristic value and prevents overshoots in the actual value. This results in predictable, smooth control, a natural steering feel, and high-performance guidance with respect to the characteristic value.
[0022] It can be implemented that the first adaptation component is determined by the second sub-controller based on the actual hand torque and / or the actual speed of the rack. By considering the actual hand torque, different driving scenarios can be distinguished, for example, by evaluating the driver's input or interaction. This influence can be adjusted via application parameters.
[0023] It can be stipulated that the first manipulated variable determined by the first sub-controller is limited by a predefined limit value. This restricts the dynamics of the steering system and makes it more stable and robust.
[0024] It may be stipulated that the target value of the parameter is limited by a predefined limit. This restricts the dynamics of the steering system and makes it more stable and robust. R.413432
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[0026] The procedure can include determining a second adaptation component, which characterizes a nominal target hand torque, depending on the difference variable, with an evaluation routine, whereby the target hand torque is determined as a function of the second adaptation component. Using the second adaptation component, different operating modes, for example, depending on a driving situation such as vehicle speed, can be efficiently considered when determining the manipulated variable. This allows different characteristics of the steering system's behavior to be represented.
[0027] The method may include at least one of the following steps: providing a third adaptation component that characterizes a damping behavior of the steering system, in particular a damping moment, for example, depending on a motion state and / or operating state of the vehicle; providing a fourth adaptation component that characterizes an inertia of the steering system, in particular a moment of inertia, for example, depending on a motion state and / or operating state of the vehicle; providing a fifth adaptation component that characterizes a determined steering feel, for example, a steering feel torque;
[0028] The target steering torque is determined based on the third, fourth, and / or fifth adaptation component. This makes the steering feel more natural and therefore improved, as it allows for consideration of physical behavior of an axle, rack, and / or steering actuator, particularly as it varies depending on the vehicle's operating state. The steering torque is determined and provided, for example, by means of a further controller.
[0029] The steering system, for example an electrically assisted steering system, in particular an electric power steering system, comprises a steering actuator, for example a servo drive, and a control device configured to perform a procedure according to the above descriptions.
[0030] The vehicle includes a steering system according to the above design, wherein the steering actuator is configured to position at least one wheel of the vehicle R.413432
[0031] - 6 -
[0032] to influence the control variable by means of an active connection, for example a rack and pinion drive with a rack.
[0033] Further embodiments are shown in the drawing and the following description. The drawing shows:
[0034] Figure 1 shows a block diagram of a control device;
[0035] Figure 2 shows a block diagram of an embodiment of a first controller of the control device;
[0036] Figure 3 shows a block diagram of an embodiment of the control device;
[0037] Figure 4 shows a flowchart of the procedure for providing a control variable to the control device;
[0038] Figure 5 is a flowchart of an embodiment of the method
[0039] Figure 6 is a schematic representation of a vehicle.
[0040] Figure 1 shows a block diagram of a control device 100. The control device 100 is configured to provide a manipulated variable 102, which characterizes a control signal of a steering actuator 302 (Fig. 6) of a steering system 300 (Fig. 6) of a vehicle 400 (Fig. 6), wherein the vehicle 400 is operated, in particular, in a semi-autonomous mode. The control device is configured to determine a difference 104 between a setpoint 106 and an actual value 108 of a characteristic variable that characterizes a direction of travel of the vehicle 400, in particular a position of a rack 304 (Fig. 6) of the steering system 300. The control device 100 is configured to determine a first adaptation component 110, depending on an actual manual torque 112 and the difference 104, by means of a first controller 116 encompassed by the control device 100.The control device 100 is configured to determine a target manual torque 114 depending on the first adaptation component 110 and the difference quantity 104. The control device 100 is configured to provide the manipulated variable 102, wherein the manipulated variable 102 depends on the target manual torque 114 and the actual value. R.413432.
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[0042] The hand torque 112 is determined by a second controller 118 included in the control device 100.
[0043] The second controller 118, for example, is designed as a PID controller and determines the manipulated variable 102 or the control signal for the steering actuator 102 depending on a difference, for example internally determined, between the target hand torque and the actual hand torque.
[0044] It may be provided that the control device 100 is integrated into the control unit of the vehicle 400 and / or the steering system 300.
[0045] Figure 2 shows a block diagram of an embodiment of the first controller 116. The first controller 116 may comprise a plurality 120 of sub-controllers, wherein the plurality 120 of sub-controllers are preferably arranged sequentially, with the first adaptation component 110 being determined by means of the plurality 120 of sub-controllers. The first controller 116 may also be configured as a cascade controller.
[0046] It can be provided that the first controller 116 comprises a first sub-controller 122, by means of which a first manipulated variable 130 in the form of a dynamic variable of the characteristic parameter, in particular a setpoint speed of the characteristic parameter, for example a setpoint speed of the rack 304, is determined depending on the difference variable 104, and by means of a second sub-controller 124 the adaptation component 110 is determined depending on the first manipulated variable 130. The dynamic variable of the characteristic parameter is, for example, a gradient or a time derivative of the characteristic parameter. The first sub-controller 122 is, for example, configured as a rack position controller and the second sub-controller 124 as a rack speed controller.
[0047] It may be provided that the first adaptation component 110 is determined by the second sub-controller 124 depending on the actual hand torque 112 and / or an actual speed 128 of the rack. The actual hand torque 112 takes into account driver input, such as steering input, when determining the adaptation component 110. R.413432
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[0049] It may be provided that the first manipulated variable 130 determined by the first sub-controller 122 is limited by a predefined limit value 126. The predefined limit value 126 is, for example, a limit value for the dynamics of the rack, such as the speed of the rack.
[0050] It may be provided that the difference quantity 104 is limited by a predetermined limit value 132.
[0051] Figure 3 shows a block diagram of an embodiment of the control device 100. The control device 100 can be configured to determine a second adaptation component 134, which characterizes a nominal target hand torque, as a function of the difference variable 104 using an evaluation routine 136, wherein the target hand torque 114 is determined as a function of the second adaptation component 134. The evaluation routine 136 can, for example, be configured as one or more lookup tables or functions, wherein, for example, a lookup table or function is selected depending on a motion state, such as a speed, of the vehicle. The function or the lookup table maps, for example, the difference variable 104 to a corresponding second adaptation component 134, which represents a corresponding nominal target hand torque.
[0052] The control device 100 may be configured to provide a third adaptation component 138, which characterizes the damping behavior of the steering system 300, in particular a damping torque, for example, depending on a motion state and / or operating state of the vehicle 400. The motion state may, for example, be the speed of the vehicle 400. The third adaptation component 138 may, for example, be provided or determined by an evaluation routine.
[0053] It may be provided that the control device 100 is configured to provide a fourth adaptation component 140, which characterizes an inertia of the steering system 300, in particular a moment of inertia, for example depending on the state of motion and / or operating state of the vehicle 400. R.413432
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[0055] The fourth adaptation component 140 can, for example, be provided or determined by an evaluation routine.
[0056] The control device 100 may be configured to provide a fifth adaptation component 142 that characterizes a determined steering feel, for example, a steering feel torque. The determined steering feel in the form of the steering feel torque can, for example, be determined and provided by a controller.
[0057] The control device 100 may be configured to determine the target manual torque 114 depending on the third adaptation component 138 and / or the fourth adaptation component 140 and / or the fifth adaptation component 142. The target manual torque 114 can, for example, be determined by summing the first adaptation component 110 and / or the second adaptation component 134 and / or the third adaptation component 138 and / or the fourth adaptation component 140 and / or the fifth adaptation component 142. It is also conceivable to determine the target manual torque 114 using a function, whereby these adaptation components can be used as parameters of the function.
[0058] It may be provided that the first adaptation component 110 and / or the third adaptation component 138 and / or the fourth adaptation component 140 and / or the fifth adaptation component 142 and / or the second adaptation component 134 are influenced and / or weighted by two external factors. These external factors represent a steering feel factor and a stiffness factor. The steering feel factor can be used to weight the fifth adaptation component 142 in particular. The stiffness factor weights the second adaptation component 134 and / or the first adaptation component 110 and / or the third adaptation component 138 and / or the fourth adaptation component 140 in order to, for example, influence the performance of a position control of the rack position. For example, in a hands-on operation of the steering system 300, the second adaptation component 134 can be weighted more heavily than the first adaptation component 110 in order to generate a more natural steering feel.
[0059] Whereas, for example, in hands-free operation of the steering system 300, the first adaptation component 110 is weighted more heavily to achieve more efficient steering behavior. R.413432
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[0061] Figure 4 shows a flowchart of a procedure 200 for providing the manipulated variable 102 to the control device 100. The control device 100 is configured, for example, to execute the procedure 200. The procedure comprises determining 202 the difference 104 between the setpoint 106 and the actual value 108 of the parameter that characterizes a direction of travel of the vehicle 400, and determining 204 the first adaptation component 110 depending on the actual manual torque 112 and the difference 104 by means of the first controller 116 included by the control unit 100. The procedure 200 comprises determining 206 the setpoint manual torque 114 depending on the first adaptation component 110 and the difference 104, and providing 208 the manipulated variable 102, wherein the manipulated variable 102 is determined depending on the setpoint manual torque 114 and the actual manual torque 112 by the second controller 118 included by the control unit 100.
[0062] It may be provided that the first controller 116 includes a first sub-controller 122, by means of which, depending on the difference quantity 104, the first manipulated variable 130 is determined in the form of a dynamic quantity of the characteristic variable, in particular the setpoint speed of the characteristic variable, for example the setpoint speed of the rack 304, and by means of the second sub-controller 124, depending on the first manipulated variable 130, the adaptation component 110 is determined.
[0063] It can be provided that the first adaptation component 110 is determined by the second sub-controller 124 depending on the actual manual torque 112 and / or an actual speed 128 of the rack. The actual speed 128 of the rack serves, for example, as part of a position control of the rack to follow a requested or predefined travel trajectory.
[0064] It may be provided that the first manipulated variable 130 determined by the first sub-controller 122 is limited by the specified limit value 126.
[0065] It may be stipulated that the difference quantity 104 is limited by the specified limit value 132. R.413432
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[0067] Figure 5 shows a flowchart of an embodiment of the method 200. It can be provided that the method 200 includes determining 210 the second adaptation component 134 depending on the difference quantity 104 with the evaluation routine 136, wherein the target manual torque 114 is determined 206 depending on the second adaptation component 134.
[0068] It may be provided that the method 200 comprises at least one of the following steps: providing 212 the third adaptation component 138, which characterizes a damping behavior of the steering system 300, in particular a damping torque, for example, depending on the state of motion and / or operating state of the vehicle 400; providing 214 the fourth adaptation component 140, which characterizes an inertia of the steering system 300, in particular a moment of inertia, for example, depending on the state of motion and / or operating state of the vehicle 400; providing 216 the fifth adaptation component 142, which characterizes a determined steering feel, for example, a steering feel torque; wherein the target hand torque 114 is determined 206 depending on the third adaptation component 138 and / or fourth adaptation component 140 and / or the fifth adaptation component 142.
[0069] Figure 6 shows a schematic representation of the vehicle 400, which includes the steering system 400. The steering system 300, for example an electrically assisted steering system, in particular an electric power steering system, comprises the steering actuator 302, for example a servo drive, and the control unit 100, which is configured to execute the method 200. The control unit 100 may be implemented in a computing unit, for example a control unit. This computing unit may be located centrally within the steering system 300 or decentrally to the steering system 300.
[0070] The vehicle 400 comprises the steering system 300, wherein the steering actuator 302 is designed to influence the position of at least one wheel 402 of the vehicle 400 by means of an operative connection, for example a rack and pinion drive 303 with a rack 304 and an axle, depending on the actuating variable 102.
Claims
R.413432 - 12 - Claims 1. Method (200) for providing a control variable (102) to a control device (100) that characterizes a control signal of a steering actuator (302) of a steering system (300) of a vehicle (400), wherein the vehicle (400) is operated in a semi-autonomous mode, comprising: Determine (202) a difference (104) between a target value (106) and an actual value (108) of a characteristic parameter that characterizes a direction of travel of the vehicle (400), in particular a position of a rack (304) of the steering system (300); Determining (204) a first adaptation component (110) depending on an actual hand torque (112) and the difference quantity (104) by means of a first controller (116) encompassed by the control device (100); Determining (206) a target hand torque (114) depending on the first adaptation component (110) and the difference quantity (104); Providing (208) the manipulated variable (102), wherein the manipulated variable (102) is determined depending on the setpoint manual torque (114) and the actual manual torque (112) by a second controller (118) encompassed by the control device (100).
2. The method (200) according to claim 1, wherein the first controller (116) comprises a plurality (120) of sub-controllers, wherein the plurality (120) of sub-controllers are in particular provided sequentially, wherein the first adaptation component (110) is determined (204) by means of the plurality (120) of sub-controllers.
3. The method (200) according to claim 2, wherein the first controller (116) comprises a first sub-controller (122) by means of which, depending on the difference quantity (104), a first manipulated variable (130) in the form of a dynamic quantity of the characteristic variable, in particular a setpoint speed of the characteristic variable, for example a setpoint speed of the rack (304), R.413432 - 13 - is determined and the adaptation component (110) is determined by means of a second sub-controller (124) depending on the first manipulated variable (130).
4. The method (200) according to claim 3, wherein the first adaptation component (110) is determined by means of the second sub-controller (124) depending on the actual manual torque (112) and / or an actual speed (128) of the rack.
5. The method (200) according to one of claims 3 or 4, wherein the first manipulated variable (130) determined by the first sub-controller (122) is limited by a predetermined limit value (126).
6. The method (200) according to one of the preceding claims, wherein the target value (106) of the characteristic parameter is limited by a predetermined limit value (132).
7. The method (200) according to any one of the preceding claims, comprising: Determining (210) a second adaptation component (134) that characterizes a nominal target hand torque, depending on the difference quantity (104) using an evaluation routine (136); where the target hand torque (114) is determined depending on the second adaptation component (134) (206).
8. The method (200) according to any of the preceding claims, comprising at least one of the following steps: Providing (212) a third adaptation component (138) that characterizes a damping behavior of the steering system (300), in particular a damping moment, for example depending on a motion state and / or operating state of the vehicle (400); Providing (214) a fourth adaptation component (140) that characterizes an inertia of the steering system (300), in particular a moment of inertia, for example, depending on a motion state and / or operating state of the vehicle (400); providing (216) a fifth adaptation component (142) that characterizes a determined steering feel, for example, a Steering feel torque; R.413432 - 14 - wherein the target hand torque (114) is determined depending on the third adaptation component (138) and / or fourth adaptation component (140) and / or fifth adaptation component (142) (206).
9. Steering system (300), for example an electrically assisted steering system, in particular an electric power steering system, comprising a steering actuator (302), for example a servo drive, and a control device (100) configured to perform a method (200) according to claims 1 to 8.
10. Vehicle (400) comprising a steering system (300) according to claim 9, wherein the steering actuator (302) is configured to influence the position of at least one wheel (402) of the vehicle (400) by means of an operative connection, for example a rack and pinion drive (303) with a rack (304), depending on the actuating variable (102).