MDPS Steering Return Control via Yaw Rate Feedback
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Solution Overview
Problem
Motor Driven Power Steering (MDPS) systems face challenges in returning the steering wheel to its neutral position accurately due to distorted wheel alignment and errors in the steering angle sensor, leading to degraded return control performance.
Innovation Solution
A steering return control apparatus and method that includes a vehicle speed sensor, yaw rate sensor, column torque sensor, and motor encoder, which work together with a return controller to determine the neutral drive state of the vehicle, calculate and apply a return torque to correct the steering wheel's position, adjusting gains based on vehicle speed and column torque to ensure precise return control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If return torque is calculated based on steering angle to assist returning operation, then steering wheel return performance is improved, but wheel alignment distortion and sensor errors cause return control accuracy to deteriorate
Solution Approach 1:
The system continuously monitors vehicle speed, yaw rate, and column torque to detect the neutral drive state, using this feedback to dynamically correct the target position value. This closed-loop feedback mechanism compensates for alignment distortion and sensor errors, maintaining return control accuracy while preserving the benefits of return torque assistance.
Solution Approach 2:
The system changes the reference parameter for return control from a fixed steering angle-based target position to a dynamically determined target position value based on actual neutral drive state detection. This parameter change allows the system to adapt to varying operating conditions and compensate for mechanical distortions and sensor drift.
2Measurement precision
If multiple sensors and real-time monitoring are added to detect neutral drive state, then return control accuracy is improved, but device complexity increases
Solution Approach 1:
The system leverages existing sensors (vehicle speed sensor, yaw rate sensor, column torque sensor) that serve multiple functions in the MDPS system. By reusing these sensors for neutral state detection in addition to their primary functions, the system avoids adding dedicated hardware while achieving accurate return control.
Solution Approach 2:
The system uses the vehicle's own operational parameters (speed, yaw rate, torque) to self-determine its neutral state without requiring external reference systems. This self-service approach eliminates the need for additional complex sensing infrastructure while maintaining detection accuracy.
Data Source
AI summary
A steering return control apparatus of an MDPS may include: a vehicle speed sensor configured to detect a vehicle speed; a yaw rate sensor configured to sense a tilted state of the vehicle, and output a yaw rate value; a column torque sensor configured to detect a column torque applied to a steering shaft; a motor encoder configured to detect a rotation amount of a motor; and a return controller configured to receive the vehicle speed, the yaw rate value and the column torque, determine whether the vehicle is driven in a neutral state, calculate a rack position and rack speed from the rotation amount of the motor, set a target position value in the neutral drive state, calculate a return torque for returning a steering wheel to the target position value, adjust a gain according to the vehicle speed and column torque, and output a return torque driving value.