Motor Control Backlash Compensation via Velocity Inversion Gain
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional motor control devices fail to accurately compute backlash compensation due to neglecting the time necessary for velocity inversion, leading to inappropriate compensation amounts during machining processes, especially when working with varying circular paths and workpieces.
Innovation Solution
A motor control device that includes a position command calculation unit, position detecting units, an error computing unit, a memory unit, an acceleration computing unit, a compensation gain computing unit, and a compensation amount computing unit, which calculates a backlash compensation amount by considering the time for velocity inversion and sets an upper limit to prevent excessive compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If backlash compensation is calculated without considering velocity inversion time, then the compensation calculation is simple, but the positioning accuracy deteriorates when machining along circular paths with varying radii and velocities
Solution Approach 1:
The system performs preliminary detection of engagement positions where the movable part engages with the driven part, and pre-calculates the relationship between acceleration commands and velocity inversion times. This preliminary action allows the system to store engagement position information and use it for accurate real-time backlash compensation without complex calculations during actual machining operations.
Solution Approach 2:
The system implements feedback by detecting the actual engagement position between the movable part and driven part, comparing it with the commanded position, and using this feedback information to calculate accurate backlash compensation amounts. The feedback loop continuously monitors and adjusts compensation based on actual system behavior during velocity inversion.
2Manufacturing precision
If the backlash compensation amount is increased to account for velocity inversion time, then the positioning accuracy improves, but the risk of excessive compensation increases
Solution Approach 1:
The system dynamically adjusts the backlash compensation amount based on the actual acceleration command being executed. By making the compensation amount proportional to the acceleration command, the system adapts to varying machining conditions in real-time, ensuring accurate compensation without excessive values. This dynamic approach replaces fixed compensation values with adaptive calculations.
Solution Approach 2:
The system changes the parameter of compensation amount from a fixed value to a variable that depends on the acceleration command. This parameter change allows the compensation to scale appropriately with the machining conditions, preventing both insufficient and excessive compensation across different operating scenarios.
3Productivity
If the velocity inversion time is neglected in compensation calculation, then the control response is fast, but the compensation amount becomes inappropriate for different workpiece types and machining routes
Solution Approach 1:
The system performs preliminary detection and storage of engagement positions where the movable part contacts the driven part. This preliminary action captures the mechanical characteristics of the system once, and the stored engagement position information is then reused for various machining operations, providing adaptability without requiring real-time analysis for each new workpiece or route.
Solution Approach 2:
The system uses parameter changes by making the backlash compensation amount proportional to the acceleration command. This allows the compensation to automatically adapt to different machining conditions (circular paths, linear paths, varying velocities) by scaling with the actual acceleration being applied, maintaining both response speed and adaptability.
Data Source
AI summary
A motor control device includes a first position detecting unit for detecting a position of a movable part, a second position detecting unit for detecting a position of a driven part, an error computing unit for computing an error between a first position detection value detected by the first position detecting unit and a second position detection value detected by the second position detecting unit, a memory unit for memorizing, as an initial error, an error computed when the movable part engages with the driven part, a compensation amount computing unit for computing a backlash compensation amount for compensating backlash, a compensation gain computing unit for computing a compensation gain based on the acceleration command, and a compensation amount computing unit for computing the backlash compensation amount using the compensation gain.