Velocity-Dependent Damping for Power Steering Stability
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Solution Overview
Problem
Power steering systems face instability issues due to torque disturbances caused by motors, particularly at higher hand wheel speeds, despite using frequency-dependent damping algorithms to improve stability and reject disturbances.
Innovation Solution
A control system that determines a scaled damping factor by processing signals from sensors, using a velocity blend function to adjust damping gains based on component velocities, ensuring higher gains at low speeds and lower gains at higher speeds to maintain stability across varying hand wheel speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If frequency dependent damping algorithms are used to improve system stability, then system stability is improved, but torque disturbances are not effectively limited at higher hand wheel speeds
Solution Approach 1:
The damping factor is made dynamic by scaling it according to the absolute value of the hand wheel velocity. The processor determines a scaled damping factor by multiplying a damping factor with a scale factor derived from the velocity, allowing the damping effect to adapt to different operating conditions and effectively limit torque disturbances at both low and high speeds
Solution Approach 2:
The damping parameter is changed based on velocity conditions. The system changes the damping factor from a fixed value to a velocity-dependent scaled value, where the scale factor is determined from the absolute value of the hand wheel velocity, optimizing the damping effect for different speed ranges
2Object-affected harmful factors
If high damping gains are used to limit torque disturbances at low speeds, then torque disturbance rejection is improved, but system instabilities occur at higher speeds
Solution Approach 1:
The damping gain is made dynamic through velocity-based scaling. At low hand wheel speeds, the scaled damping factor provides high damping effect to limit torque disturbances, while at higher speeds, the scaling automatically reduces the damping effect to prevent system instabilities, achieving adaptive control across the full speed range
Solution Approach 2:
The damping parameter is adjusted based on velocity conditions. The system uses a scale factor determined from the absolute value of hand wheel velocity to modify the damping factor, providing high damping gains at low speeds for effective disturbance rejection and lower gains at high speeds for stability maintenance
Data Source
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AI summary
A method for controlling a power steering system, the method including, receiving a first signal, determining a velocity from the first signal, determining a scale factor from a function of the velocity, multiplying the scale factor with a damping factor, and outputting a scaled damping factor.