A torque compensation control method for a chassis domain EPS system

Abstract

This invention provides a torque compensation control method for a chassis-domain EPS system, comprising: acquiring current vehicle information; performing oversampling sign expansion, electric power steering control, motor characteristic compensation, vehicle characteristic compensation, stabilization compensation, rack-end steering characteristic control, and steering vibration compensation on the acquired information; fusing the calculated results to obtain the target assist torque; and quantizing and compensating for noise reduction in the target assist torque before outputting it. This invention, based on an electric power steering control strategy in chassis-domain control, features fast response, minimal hardware requirements, low cost, and high safety.

Description

Technical Field

[0001] This invention relates to the field of automotive control technology, and more specifically, to a torque compensation control method for a chassis-domain EPS system. Background Technology

[0002] With societal progress and advancements in automotive and electronic technologies, traditional power steering systems no longer meet the demands of modern automotive development, leading to the evolution of electric power steering systems. The "Fuzzy Self-Adjustment of Electric Power Steering Systems" explains that the source of steering assistance in electric power steering (EPS) is an electric motor, driven by current supplied by the vehicle's battery. At high speeds, when steering assistance is not required or even damping assistance is needed, the battery only needs to provide a small control current, adapting to the requirements of modern automotive development.

[0003] Electric power steering (EPS) systems add motors, various sensors, electronic control devices, and reduction mechanisms to the traditional mechanical steering system, providing appropriate steering assistance to the driver under different driving conditions such as different vehicle speeds and torque levels.

[0004] The main problem with existing technology is that the distributed powertrain architecture inherently limits the real-time response of Electronic Power Steering (EPS). It requires collecting signals such as steering torque, vehicle speed, steering angle, and motor speed, performing control calculations on these signals, and ultimately outputting the current value to control the motor. Both the signal collection and the current calculations for outputting torque take a considerable amount of time, resulting in a subjective response lag that affects the driver's driving feel.

[0005] Currently, the control methods of electric power steering systems in various automobiles have certain limitations, as detailed below:

[0006] 1. The torque sensor of the electric power steering system measures the steering torque, steering angle and steering speed signals applied by the driver to the steering wheel, while the vehicle speed sensor measures the current vehicle speed and engine speed signals.

[0007] 2. The CAN signal transmits the measured torque, steering angle and steering speed signals, vehicle speed, engine speed and other signals to the electronic control unit;

[0008] 3. The ECU (Electronic Control Unit) calculates the ideal target current based on its own assist characteristic curve and control strategy, and then converts it into the current controlling the motor and the direction of motor rotation;

[0009] 4. The motor generates assist torque based on the current output by the ECU. The assist torque is transmitted to the steering mechanism through the reduction mechanism, and together with the driver's steering torque, it overcomes the steering resistance torque and provides appropriate assistance to the driver.

[0010] The above are all control strategies based on the control unit.

[0011] When the driver intends to steer, the steering wheel torque is changed. The control unit collects vehicle speed information and torque changes, and receives current vehicle information (such as vehicle speed, motor speed, and steering torque) via CAN signals to recalculate the target current and target torque requirements. The main drawbacks of this approach are as follows:

[0012] There is a certain response delay, and there is a response lag;

[0013] CAN communication signals are susceptible to electromagnetic interference, which can lead to frame loss and reduce security.

[0014] The large number of motors and controllers resulted in excessively high costs.

[0015] Given the drawbacks of the above strategies, a new electric power steering control strategy is needed. Summary of the Invention

[0016] This invention addresses the technical problems existing in the prior art by providing a torque compensation control method for a chassis domain EPS system. Based on the electric power steering control strategy in chassis domain control, it features fast response, less hardware, low cost, and high safety.

[0017] The technical solution of this invention to solve the above-mentioned technical problems is as follows: A torque compensation control method for a chassis domain EPS system, comprising:

[0018] The system collects current vehicle information, performs oversampling symbol expansion, electric power assist control, motor characteristic compensation, vehicle characteristic compensation, stabilization compensation, rack end steering characteristic control, and steering vibration compensation on the collected information, and then fuses the calculated results to obtain the target assist torque. The target assist torque is then quantized, noise reduction and compensation are performed, and the result is output.

[0019] Based on the above technical solution, the present invention can also be improved as follows.

[0020] Optionally, the collected current vehicle information may include at least:

[0021] Steering torque, motor speed, vehicle speed control, friction torque, LPF (low-pass filter) cutoff frequency ratio, steering angle, PDC compensation (drift compensation) torque, left rudder maximum steering angle signal, right rudder maximum steering angle signal, rack and pinion angle usage permit signal, steering angle and steering speed usage permit signal, and stability compensation boost torque.

[0022] Optionally, oversampling symbol expansion is performed, including:

[0023] The steering torque and motor speed signals are oversampled and symbolically expanded to output the symbolically expanded steering torque, symbolically expanded motor speed, and symbolically expanded steering speed signals.

[0024] Optionally, electric power assist control can be implemented, including:

[0025] The vehicle speed control signal, the steering torque signal after sign expansion, the motor speed signal after sign expansion, the friction torque signal, and the LPF cutoff frequency ratio signal are input into the electric power steering control module. The steering torque LPF processing, basic power assist torque processing, responsive phase compensation processing, phase compensation processing, SAT (Self-aligning-torque) compensation processing, and hysteresis compensation processing are performed respectively to output the electric power assist control torque and the steering torque signal after LPF.

[0026] Optionally, vehicle characteristic compensation may be performed, including:

[0027] The steering speed signal, steering angle signal, LPF steering torque signal, and symbol-expanded motor speed signal are input into the vehicle characteristic compensation module. The module performs SW (software) steering angle and steering speed calculation processing, damping control processing, steering wheel return speed and torque processing, active return control processing, and angle control compensation torque calculation processing to output the return speed torque signal and the angle control compensation torque signal.

[0028] Optionally, motor characteristic compensation can be performed, including:

[0029] The sign-expanded motor speed signal, sign-expanded steering torque signal, LPF-fed steering torque signal, and vehicle speed control signal are input into the motor characteristic compensation module, where torque differential compensation, torque second-order differential compensation, motor inertia compensation, motor back electromotive force (EMF) compensation, and motor torque loss compensation are performed respectively to output differential torque signal, second-order differential torque signal, motor characteristic compensation torque signal, and friction torque signal.

[0030] Optionally, stabilization compensation may be performed, including:

[0031] The electric power assist control torque signal, the differential torque signal, and the return speed torque signal are input to the stabilization compensation module, where they are processed by signal splitting, addition synthesis, and phase compensation, respectively, to output the stabilized and compensated power assist torque signal.

[0032] Optionally, rack-end steering characteristic control can be performed, including:

[0033] The stable compensation-adjusted assist torque signal, steering angle signal, sign-expanded steering speed signal, sign-expanded steering torque signal, control speed signal, left rudder maximum steering angle signal, right rudder maximum steering angle signal, rack angle usage permission signal, and steering angle and steering speed usage permission signal are input to the rack end steering characteristic control module for rack end limiting processing, so as to output the rack end compensation-adjusted assist torque signal.

[0034] Optional, rudder vibration compensation can be performed, including:

[0035] The rack end compensation torque signal, second derivative torque signal, angle control compensation torque signal, PDC compensation torque signal, sign expansion steering torque signal, and control speed signal are input to the steering vibration compensation module. The LPF cutoff frequency determination processing and target assist torque LPF processing are performed respectively to output the steering vibration compensation assist torque signal.

[0036] Optionally, fusing the calculated results to obtain the target assist torque includes:

[0037] The motor characteristic compensation torque, the stabilized compensation boost torque, and the steering vibration compensation boost torque are input to the additive unit and fused to obtain the target boost torque.

[0038] This invention provides a torque compensation control method for a chassis-domain EPS system, based on an electric power steering control strategy within the chassis domain control. This method achieves a smaller self-centering angle and faster steering wheel return speed, with fast signal response, significantly improved return-centering efficiency, and greatly enhanced safety during high-speed vehicle operation. It involves fewer hardware components, resulting in lower hardware costs. Drivers can obtain the necessary appropriate steering force and comfortable steering control characteristics, enabling them to appropriately perceive the vehicle's motion state and provide a smoother, quieter, and more reliable driving experience. Attached Figure Description

[0039] Figure 1 This is a schematic diagram illustrating the working principle of an EPS system.

[0040] Figure 2 This is a schematic diagram of the EPS system's workflow;

[0041] Figure 3 This is a schematic diagram of the functional modules of the torque compensation control method provided by the present invention. Detailed Implementation

[0042] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0043] Figure 1 This is a schematic diagram illustrating the working principle of an EPS system. Figure 1 As shown, the working principle of the EPS system is as follows: The torque sensor of the EPS system measures the steering torque applied by the driver to the steering wheel, and the vehicle speed sensor measures the current vehicle speed and engine speed, etc. These signals are then transmitted to the electronic control unit (ECU) through the circuit. The ECU calculates the ideal target current based on its own power assist characteristic curve and control strategy, which is then converted into the current controlling the power assist motor and the motor's steering direction. The power assist motor then generates assist torque and transmits power to the steering mechanism through the transmission device. When the EPS system malfunctions, the power assist motor does not provide assistance; when the car is traveling in a straight line, the electronic control unit does not send steering commands to the motor, and the power assist motor does not work.

[0044] Figure 2 This is a schematic diagram of the EPS system's workflow. Based on... Figure 1 The working principle, such as Figure 2 As shown, after confirming the steering command is issued, the ECU collects signals from various sensors in the vehicle, processes and calculates them, and outputs the target current to control the power assist motor. The target current generates a suitable assist torque through the motor. The assist torque of the motor drives the steering mechanism to perform steering assistance work after passing through the transmission device, thereby realizing the steering control of the vehicle.

[0045] like Figure 3 The diagram shown illustrates the functional modules of the torque compensation control method provided in an embodiment of the present invention. The present invention aims to provide an electronic power steering (EPS) system that satisfies the driver's comfortable steering experience. Based on the above requirements, such as... Figure 3 As shown, the EPS controller includes Figure 3 The following functional modules are shown: oversampling sign expansion, electric power steering control, vehicle characteristic compensation, motor characteristic compensation, stabilization compensation, rack end steering characteristic control, steering vibration compensation, and quantization noise reduction compensation. These eight functional modules work together to form the electronic power steering system.

[0046] This invention provides a torque compensation control method for a chassis-domain EPS system, comprising:

[0047] The system collects current vehicle information, performs oversampling symbol expansion, electric power assist control, motor characteristic compensation, vehicle characteristic compensation, stabilization compensation, rack end steering characteristic control, and steering vibration compensation on the collected information, and then fuses the calculated results to obtain the target assist torque. The target assist torque is then quantized, noise reduction and compensation are performed, and the result is output.

[0048] Understandably, given the deficiencies in the background technology, this invention proposes a torque compensation control method for a chassis-domain EPS system, based on an electric power steering control strategy within the chassis domain control. This method achieves a smaller self-centering angle and faster steering wheel return speed, with fast signal response, significantly improved return-to-center efficiency, and greatly enhanced safety during high-speed vehicle operation. Due to the limited number of hardware components involved in the control, hardware costs are low. Drivers can obtain the necessary appropriate steering force and comfortable steering control characteristics, enabling them to appropriately perceive the vehicle's motion state and provide a smoother, quieter, and more reliable driving experience.

[0049] In one possible embodiment, such as Figure 3 As shown, the collected current vehicle information includes at least:

[0050] Steering torque, motor speed, vehicle speed control, friction torque, LPF (low-pass filter) cutoff frequency ratio, steering angle, PDC compensation (deviation compensation) torque, left rudder maximum steering angle signal (Rel_l_max), right rudder maximum steering angle signal (Rel_r_max), rack angle usage permit signal (Rel_end_vld), steering angle and steering speed usage permit signal, and stability compensation boost torque.

[0051] Understandably, some of the vehicle's current information comes from sensors in the vehicle's EPS system, such as steering torque, motor speed, control speed, and steering angle; while other information comes from the outputs of various functional modules, such as friction torque, LPF (low-pass filter) cutoff frequency ratio, PDC compensation (pairing compensation) torque, left rudder maximum steering angle signal, right rudder maximum steering angle signal, rack angle usage permit signal, steering angle and steering speed usage permit signal, and stability compensation boost torque.

[0052] In one possible embodiment, oversampling symbol expansion includes:

[0053] The steering torque and motor speed signals are oversampled and symbolically expanded to output the symbolically expanded steering torque, symbolically expanded motor speed, and symbolically expanded steering speed signals.

[0054] Understandably, oversampling sign expansion, consisting of a moving weighted average with sign expansion, is used to improve the accuracy of the input signal.

[0055] In one possible embodiment, electric power assist control includes:

[0056] The vehicle speed control signal, the steering torque signal after sign expansion, the motor speed signal after sign expansion, the friction torque signal, and the LPF cutoff frequency ratio signal are input into the electric power steering control module. The steering torque LPF processing, basic power steering torque processing, responsive phase compensation processing, phase compensation processing, SAT compensation processing, and hysteresis compensation processing are performed respectively to output the electric power steering control torque and the steering torque signal after LPF.

[0057] It is understandable that by controlling the vehicle speed signal, the steering torque signal after sign expansion, the motor speed signal after sign expansion, and the friction torque signal for electric power assist, quiet and smooth electric power assist can be obtained.

[0058] In one possible embodiment, such as Figure 3 As shown, vehicle characteristic compensation includes:

[0059] The steering speed signal, steering angle signal, steering torque signal after LPF expansion, steering torque signal after symbol expansion, and motor speed signal after symbol expansion are input into the vehicle characteristic compensation module. Software (SW) steering angle and steering speed calculation processing, damping control processing, steering wheel return speed and torque processing, active return control processing, and angle control compensation torque calculation processing are performed respectively to output the return speed torque signal and the angle control compensation torque signal.

[0060] Understandably, the vehicle characteristic compensation module consists of return position control, return speed control, and damping control. Through vehicle characteristic compensation, the driver can appropriately perceive the vehicle's condition by steering.

[0061] In one possible embodiment, motor characteristic compensation includes:

[0062] The sign-expanded motor speed signal, sign-expanded steering torque signal, LPF-fed steering torque signal, and vehicle speed control signal are input into the motor characteristic compensation module, where torque differential compensation, torque second-order differential compensation, motor inertia compensation, motor back electromotive force (EMF) compensation, and motor torque loss compensation are performed respectively to output differential torque signal, second-order differential torque signal, motor characteristic compensation torque signal, and friction torque signal.

[0063] Understandably, motor characteristic compensation can reduce the torque loss of motor inertia and magnetism to a certain extent, thereby improving the accuracy of torque control.

[0064] In one possible embodiment, stabilization compensation includes:

[0065] The electric power assist control torque signal, the differential torque signal, and the return speed torque signal are input to the stabilization compensation module, where they are processed by signal splitting, addition synthesis, and phase compensation, respectively, to output the stabilized and compensated power assist torque signal.

[0066] Understandably, the stabilization compensation module mainly consists of stability phase compensation and robust stabilization compensation. It processes the electric power assist control torque signal output by the electric power assist control module, the differential torque signal output by the motor characteristic compensation module, and the return speed torque signal output by the vehicle characteristic compensation module, so that the driver can obtain comfortable steering control characteristics.

[0067] In one possible embodiment, rack-end steering characteristic control includes:

[0068] The stable compensation-adjusted assist torque signal, steering angle signal, sign-expanded steering speed signal, sign-expanded steering torque signal, control speed signal, left rudder maximum steering angle signal, right rudder maximum steering angle signal, rack angle usage permission signal, and steering angle and steering speed usage permission signal are input to the rack end steering characteristic control module for rack end limiting processing, so as to output the rack end compensation-adjusted assist torque signal.

[0069] Understandably, the rack end steering characteristic control module mainly consists of rack end limiters, which are used to limit the electric assist at the rack end, protect the gears, and improve vehicle safety.

[0070] In one possible embodiment, steering vibration compensation includes:

[0071] The rack end compensation torque signal, second derivative torque signal, angle control compensation torque signal, PDC compensation torque signal, sign expansion steering torque signal, and control speed signal are input to the steering vibration compensation module. The LPF cutoff frequency determination processing and target assist torque LPF processing are performed respectively to output the steering vibration compensation assist torque signal.

[0072] Understandably, the steering vibration compensation module mainly consists of low-pass cutoff frequency calculation and assist torque low-pass filtering. Steering vibration compensation can reduce the quantization noise caused by steering.

[0073] In one possible embodiment, fusing the calculated results to obtain the target assist torque includes:

[0074] The motor characteristic compensation torque, the stabilized compensation boost torque, and the steering vibration compensation boost torque are input to the additive unit and fused to obtain the target boost torque.

[0075] Because the target assist torque output by the additive section also has a certain amount of noise, therefore... Figure 3 As shown, after quantizing and reducing noise to compensate for the target assist torque output by the additive unit, the filtered target assist torque is obtained and output.

[0076] This invention provides a torque compensation control method for a chassis-domain EPS system, based on an electric power steering control strategy within the chassis domain control. This method achieves a smaller self-centering angle and faster steering wheel return speed, with fast signal response, significantly improved return-centering efficiency, and greatly enhanced safety during high-speed vehicle operation. It involves fewer hardware components, resulting in lower hardware costs. Drivers can obtain the necessary appropriate steering force and comfortable steering control characteristics, enabling them to appropriately perceive the vehicle's motion state and provide a smoother, quieter, and more reliable driving experience.

[0077] It should be noted that the descriptions of each embodiment in the above embodiments have different focuses. For parts that are not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0078] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0079] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0080] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0081] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0082] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0083] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A torque compensation control method for a chassis-domain EPS system, characterized in that, include: The collected current vehicle information includes at least the following: Steering torque, motor speed, vehicle speed control, friction torque, LPF cutoff frequency ratio, steering angle, PDC compensation torque, left rudder maximum steering angle signal, right rudder maximum steering angle signal, rack and pinion angle usage permit signal, steering angle and steering speed usage permit signal, and stability compensation boost torque. After performing oversampling symbol expansion, electric power assist control, motor characteristic compensation, vehicle characteristic compensation, stabilization compensation, rack end steering characteristic control, and steering vibration compensation on the collected information, the calculated results are fused to obtain the target assist torque. Among them, oversampling symbol expansion includes: The steering torque and motor speed signals are oversampled and symbolically expanded to output the symbolically expanded steering torque, symbolically expanded motor speed, and symbolically expanded steering speed signals. Performing electric power assist control includes: The vehicle speed control signal, the steering torque signal after sign expansion, the motor speed signal after sign expansion, the friction torque signal, and the LPF cutoff frequency ratio signal are input into the electric power assist control module. The steering torque LPF processing, basic assist torque processing, responsive phase compensation processing, phase compensation processing, SAT compensation processing, and hysteresis compensation processing are performed respectively to output the electric power assist control torque and the steering torque signal after LPF. Vehicle characteristic compensation includes: The steering speed signal, steering angle signal, LPF steering torque signal, and sign-expanded motor speed signal are input into the vehicle characteristic compensation module. Software steering angle and steering speed calculation, damping control, steering wheel return speed and torque, active return control, and angle control compensation torque calculation are performed respectively to output the return speed and torque signal and the angle control compensation torque signal. Motor characteristic compensation includes: The sign-expanded motor speed signal, sign-expanded steering torque signal, LPF-fed steering torque signal, and vehicle speed control signal are input into the motor characteristic compensation module, where torque differential compensation, torque second derivative compensation, motor inertia compensation, motor back EMF compensation, and motor torque loss compensation are performed respectively to output differential torque signal, second derivative torque signal, motor characteristic compensation torque signal, and friction torque signal. The target assist torque is quantified, noise reduction and compensation are performed, and then output.

2. The torque compensation control method for a chassis-domain EPS system according to claim 1, characterized in that, Stabilization compensation includes: The electric power assist control torque signal, the differential torque signal, and the return speed torque signal are input to the stabilization compensation module, where they are processed by signal splitting, addition synthesis, and phase compensation, respectively, to output the stabilized and compensated power assist torque signal.

3. The torque compensation control method for a chassis domain EPS system according to claim 2, characterized in that, Controlling the rack end steering characteristics includes: The stable compensation-adjusted assist torque signal, steering angle signal, sign-expanded steering speed signal, sign-expanded steering torque signal, control speed signal, left rudder maximum steering angle signal, right rudder maximum steering angle signal, rack angle usage permission signal, and steering angle and steering speed usage permission signal are input to the rack end steering characteristic control module for rack end limiting processing, so as to output the rack end compensation-adjusted assist torque signal.

4. The torque compensation control method for a chassis-domain EPS system according to claim 3, characterized in that, Performing steering vibration compensation includes: The rack end compensation torque signal, second derivative torque signal, angle control compensation torque signal, PDC compensation torque signal, sign expansion steering torque signal, and control speed signal are input to the steering vibration compensation module. The LPF cutoff frequency determination processing and target assist torque LPF processing are performed respectively to output the steering vibration compensation assist torque signal.

5. The torque compensation control method for a chassis-domain EPS system according to claim 4, characterized in that, The process of fusing the calculated results to obtain the target assist torque includes: The motor characteristic compensation torque, the stabilized compensation boost torque, and the steering vibration compensation boost torque are input to the additive unit and fused to obtain the target boost torque.

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