Steering Controller State Detection and Impedance Adjustment
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Solution Overview
Problem
Conventional steering controllers face challenges in accurately determining the steering state due to mechanical backlash, leading to delayed switching between steer-still, steer-away, and steer-back states, and difficulty in adjusting mechanical impedance without delay.
Innovation Solution
A steering controller that calculates a steer state quantity based on active and rotation properties, using conversion values to determine the current steering state, allowing for appropriate adjustment of assist torque and improved steering feel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If driver power rate is used for mechanical impedance adjustment, then the adjustment can be based on steering operation intensity, but the determination of steering state is delayed due to mechanical backlash
Solution Approach 1:
The system performs preliminary classification of steering operations into steer-away, steer-back, and stay-still states based on steering angle and angular velocity before calculating driver power rate. This preliminary state determination ensures that mechanical impedance adjustment responds immediately to the actual steering state rather than waiting for delayed power rate calculation, thus resolving the time delay caused by mechanical backlash.
Solution Approach 2:
The steering operation is segmented into distinct states (steer-away, steer-back, stay-still) based on steering angle and angular velocity thresholds. This segmentation allows the system to determine the current steering state independently and immediately, without waiting for the gradual response of driver power rate calculation, thereby eliminating the delay in mechanical impedance adjustment.
2Adaptability or versatility
If driver power rate is used for mechanical impedance adjustment, then the adjustment reflects steering operation intensity, but the adjustment amount is insufficient in steer-back state
Solution Approach 1:
The system preliminarily determines the steering state using steering angle and angular velocity before calculating driver power rate. This preliminary determination ensures accurate identification of steer-back state, allowing the system to apply appropriate mechanical impedance adjustment regardless of the lower driver power rate values characteristic of steer-back operations.
Solution Approach 2:
The system dynamically adjusts mechanical impedance based on the determined steering state rather than relying solely on driver power rate. This dynamic adjustment ensures that appropriate impedance levels are applied in each steering state, including steer-back state where driver power rate may be low, thereby improving measurement precision of steering state detection.
Data Source
AI summary
A steering controller that controls a motor to output an assist torque to steer a steering member, including a steer property calculator calculating a steer state quantity that is an index of a steering state indicating one of (i) a steer-away state, (ii) a steer-back state, or (iii) a stay-still state, an adjusted torque calculator calculating an adjusted torque based on the steer state quantity, and an instruction value calculator calculating an assist torque instruction that is an instruction value regarding a drive of the motor by using the adjusted torque. In such manner, the steer state quantity, the steer-back operation, the stay-still operation of a steering wheel, and the adjusted torque are appropriately calculated, thereby enabling an appropriate adjustment of a steering feel.