Motor Control Backlash Compensation via Encoder Feedback
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Solution Overview
Problem
Existing motor control systems face challenges in achieving accurate control of output shaft rotation due to backlash in rotation transmission systems, leading to errors and mechanical stress during backlash learning operations, which delays shift position changes in automatic transmissions.
Innovation Solution
A motor control apparatus that compensates the target motor rotation angle based on detected output shaft rotation angle differences, eliminating backlash effects by updating the target value when the output shaft and motor shaft rotate together, without requiring a prior learning operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a learning operation is performed to determine backlash amount by moving mechanical parts into mutual contact, then backlash compensation can be applied, but mechanical stress increases and malfunction risk rises
Solution Approach 1:
The patent replaces the mechanical learning operation (moving parts into contact to detect backlash) with an electrical/electronic solution. The encoder detects motor shaft position electrically, and the controller calculates backlash compensation values through software processing of encoder signals, eliminating the need for mechanical contact during learning operations.
Solution Approach 2:
The encoder serves as an intermediary device that provides electrical measurement of motor shaft position without requiring mechanical contact between transmission components. This intermediary enables backlash detection through electrical signals rather than mechanical interaction.
2Measurement precision
If a learning operation is executed immediately before shift position changeover, then accurate backlash compensation is achieved, but response time decreases
Solution Approach 1:
The patent performs backlash learning operations in advance during vehicle operation (e.g., during idle periods or normal driving conditions) rather than immediately before shift changeover. The learned backlash values are stored in memory and applied during actual shift operations, enabling immediate response without delay.
3Measurement precision
If the motor shaft rotation angle is controlled precisely based on encoder detection, then motor shaft positioning accuracy is improved, but output shaft positioning accuracy deteriorates due to backlash
Solution Approach 1:
The system uses encoder feedback from the motor shaft and implements software-based backlash compensation. The controller calculates the relationship between motor shaft and output shaft positions, determines backlash values from encoder data, and applies compensation to achieve accurate output shaft positioning despite mechanical backlash.
Data Source
AI summary
A motor control apparatus controls a motor that drives an output shaft through a rotation transmission system. The difference between a newly established output shaft target rotation angle and a detected output shaft rotation angle is obtained, a target rotation angle for the motor is derived based on that difference, and the motor is driven accordingly. When it is determined, based on the detected output shaft rotation angle, that motor rotation has at least proceeded to a point whereby backlash in the transmission system is nullified, the target motor rotation angle is updated based on the current value of the aforementioned difference.