Motor Backlash Compensation via Preliminary Engagement Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing motor control devices face challenges in providing optimal backlash compensation immediately after activation, as they rely on stored positional relationships between movable and driven units, which can be lost when power is shut off, and struggle to accurately compensate for backlash without increasing costs or reducing accuracy.
Innovation Solution
A motor control device that includes a position command generating unit, position detecting units, a difference calculating unit, a judging unit, a retaining unit, and a compensation amount calculating unit to determine engagement differences and calculate optimal backlash compensation amounts based on these differences, allowing for preliminary movements to establish engagement thresholds and adjust position commands accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a constant compensation amount corresponding to the backlash is added to a position command, then backlash compensation is provided, but the compensation may become excessively large when the movable unit does not engage with the driven unit
Solution Approach 1:
The system performs preliminary movements of the driven unit in both first and second directions before actual operation to detect engagement differences between the movable unit and driven unit. These preliminary actions establish baseline engagement data that is stored and used for accurate backlash compensation during normal operation, preventing both excessive and insufficient compensation.
Solution Approach 2:
The compensation amount is dynamically adjusted based on detected engagement differences rather than using a fixed constant value. The system changes the compensation parameter according to the actual engagement state detected during preliminary movements, allowing optimal compensation that adapts to the specific mechanical configuration.
2Manufacturing precision
If a compensation amount is set smaller than the backlash to prevent excessive compensation, then positioning accuracy is maintained, but the compensation may be too small to provide sufficient compensation at the time of reverse motion
Solution Approach 1:
The system uses feedback from position detecting units to monitor the actual movement of the driven unit and compare it with commanded movements. By detecting discrepancies between commanded and actual movements during preliminary operations, the system calculates accurate engagement differences that enable sufficient compensation without being excessive.
Solution Approach 2:
Preliminary movements are executed to establish accurate engagement characteristics before normal operation begins. This preliminary characterization ensures that the compensation amount is precisely calibrated to the actual backlash, providing sufficient compensation when needed while maintaining positioning accuracy during normal operation.
3Reliability
If stored positional relationship information is used for backlash compensation, then immediate compensation upon activation is achieved, but the information may be lost when electric power is shut off
Solution Approach 1:
The system replaces software-based storage of positional relationships with a mechanical detection approach. Instead of relying on stored data that can be lost when power is shut off, the system uses position detecting units to physically detect engagement differences during preliminary movements, ensuring compensation data is always current and accurate.
4Loss of information
If non-volatile memory is used to store positional relationship information, then information retention after power shutdown is achieved, but device cost increases
Solution Approach 1:
The invention replaces expensive non-volatile memory storage with a mechanical detection system using position detecting units. By physically detecting engagement differences during preliminary movements, the system eliminates the need for costly memory components while ensuring accurate compensation data is always available.
Solution Approach 2:
The system performs self-characterization during preliminary movements to establish engagement differences. This self-service approach eliminates the need for external storage devices, as the system generates and uses its own compensation data from actual mechanical detection, reducing overall device cost.
Data Source
AI summary
A motor control device includes a position command generating unit, a difference calculating unit for calculating a difference between a positional detection value of a movable unit and a positional detection value of a driven unit, a retaining unit for retaining, as an engaging difference, the difference when the movable unit is moved in a first or second direction to engage with the driven unit, in association with the first direction and the second direction, and a compensation amount calculating unit for calculating a backlash compensation amount based on the difference calculated by the difference calculating unit and the engaging difference retained by the retaining unit. It is determined whether or not the movable unit is engaged with the driven unit by comparing a movement amount of the driven unit with a threshold.