Motor Back-Drive Control Using Position Error and Current Feedback
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Solution Overview
Problem
Existing motor systems struggle to differentiate between external forces applied to a load and obstacles, leading to false compliance and inefficient operation.
Innovation Solution
A motor system that switches between motor-drive and back-drive modes based on conditions such as command velocity, electrical current, and position error, enabling accurate detection of external forces and avoiding false compliance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the motor system operates in motor-drive mode to maintain position, then position stability is improved, but false compliance occurs when external forces are not properly differentiated from obstacles
Solution Approach 1:
The system dynamically switches between motor-drive mode and back-drive mode based on real-time monitoring of electrical current and position error. When an external force is detected (indicated by increased current and position error), the system transitions to back-drive mode to allow compliant movement, thereby eliminating false compliance while maintaining position stability during normal operation.
Solution Approach 2:
The system continuously monitors electrical current and position error as feedback signals to distinguish between obstacles and external forces. This feedback mechanism enables the motor controller to make intelligent decisions about mode switching, improving reliability by preventing false compliance responses to legitimate external forces.
2Adaptability or versatility
If the system switches to back-drive mode to allow external force movement, then compliance with external forces is improved, but position control precision deteriorates
Solution Approach 1:
The system employs dynamic mode switching between motor-drive and back-drive modes based on real-time conditions. Position control precision is maintained in motor-drive mode, while compliance with external forces is enabled in back-drive mode. The transition between modes is governed by monitoring electrical current and position error, ensuring precision is preserved when needed and compliance is enabled when appropriate.
3Measurement precision
If the motor controller continuously monitors electrical current and position error, then detection accuracy of external forces is improved, but system complexity increases
Solution Approach 1:
The motor controller utilizes existing electrical current and position error data that are already generated during normal motor operation. By monitoring these self-generated signals, the system achieves accurate detection of external forces without requiring additional sensors or complex measurement systems, thereby maintaining detection accuracy while minimizing system complexity.
Data Source
AI summary
Techniques for controlling operations of a motor based on position errors are described. In an example, a user device sends an amount of electrical current to the motor to cause the motor to move. The user device also determines the motor is in position for a time interval despite the amount of electrical current. Based at least one the time interval and the amount of electrical current, the user device determines a position difference associated with a target position and a measured position of the motor during the time interval, and reduces the amount of electrical current based at least in part on the time interval.