Power Steering Amplitude Calibration for Consistent Feel
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Solution Overview
Problem
Electric power steering systems face inconsistencies in steering feel due to external disturbances and variations in driving conditions, which existing systems fail to adequately address through compensation commands.
Innovation Solution
A control system for power steering that includes an amplitude calculation module, an assist value module, and a command module, which determine a command amplitude and assist value based on a compensation command to generate a consistent steering feel by blending parameters like vehicle speed and damping values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a compensation command is used to reject disturbances or compensate for issues in the electric power steering system, then the steering feel consistency is improved, but the system complexity increases due to additional control parameters and calibration requirements
Solution Approach 1:
The system dynamically adjusts the amplitude of the compensation command based on operating conditions such as vehicle speed and steering angle. By changing the compensation amplitude parameter adaptively rather than using a fixed value, the system maintains consistent steering feel across different driving conditions without requiring a overly complex control structure. The amplitude calculation module computes the appropriate compensation amplitude based on current operating parameters, resolving the contradiction between reliability improvement and system complexity.
2Reliability
If the compensation command amplitude is increased to better reject disturbances, then the steering feel consistency improves, but the steering responsiveness and natural feel deteriorate due to excessive compensation
Solution Approach 1:
The system dynamically adjusts the compensation amplitude based on real-time operating conditions including vehicle speed, steering angle, and steering rate. At low speeds or during normal steering operations, the compensation amplitude is reduced or zeroed out to maintain natural steering responsiveness. At high speeds or during detected disturbance conditions, the compensation amplitude is increased to reject disturbances and maintain steering feel consistency. This dynamic adjustment resolves the contradiction between steering feel consistency and steering responsiveness.
Solution Approach 2:
The amplitude calculation module continuously modifies the compensation command amplitude parameter based on operating conditions. By changing this parameter adaptively rather than using a fixed high amplitude, the system achieves disturbance rejection when needed while preserving natural steering feel during normal operation, thus resolving the contradiction between steering feel consistency and steering responsiveness.
3Reliability
If multiple compensation parameters are used to address various disturbances and variations, then the steering feel consistency across different products and conditions improves, but the calibration and tuning difficulty increases
Solution Approach 1:
The system incorporates pre-calibrated lookup tables and maps that store optimal compensation amplitude values for different operating conditions. During product development and tuning, these tables are pre-populated with calibrated values, eliminating the need for complex real-time calibration during manufacturing or field operation. The amplitude calculation module simply references these pre-calibrated values based on current operating conditions, resolving the contradiction between steering feel consistency across products and calibration difficulty.
Solution Approach 2:
The system uses a limited set of key parameters (vehicle speed, steering angle, steering rate) to determine compensation amplitude, rather than requiring calibration of numerous complex parameters. The amplitude calculation module computes compensation based on changes in these fundamental operating parameters, simplifying the calibration process while still achieving consistent steering feel across different products and conditions.
Data Source
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AI summary
A control system for a power steering system is provided. The control system includes an amplitude calculation module and a command module. The amplitude calculation module receives a compensation command. The amplitude calculation module determines a command amplitude that is based on the compensation command. The command module generates a command to the power steering system. The command is based on the command amplitude.