Robot Force Control Tuning Across Multiple Error Directions
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Solution Overview
Problem
Existing robot systems face challenges in optimizing force control parameters, leading to potential robot oscillation and production quality issues, especially when adjusting parameters based on varying position and posture error conditions.
Innovation Solution
A robot system with a control device that automatically adjusts force control parameters by moving the workpiece from multiple posture error directions, ensuring optimal parameter settings that prevent robot oscillation and ensure successful task execution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If force control parameters are automatically adjusted based on a single position and posture error condition, then the adjustment process is simple and quick, but the adjusted parameters are not optimized and may cause robot oscillation or work failure under different error conditions
Solution Approach 1:
The patent segments the parameter adjustment process into multiple independent trials, each conducted under different position and posture error conditions. The control device performs force control parameter adjustment separately for each error condition, then integrates the results to determine optimal parameters, ensuring both efficiency and reliability
Solution Approach 2:
The patent extends the parameter adjustment from a single error condition to multiple error conditions by adding the dimension of error direction variation. By adjusting parameters across different posture error directions (e.g., radial, tangential, axial directions), the system ensures optimized performance under diverse operating conditions
2Ease of operation
If force control parameters are adjusted on conditions with high oscillation limit, then the adjustment is easier, but the robot may oscillate during production affecting quality or causing damage
Solution Approach 1:
The patent performs preliminary parameter adjustment trials under controlled error conditions before actual production. By pre-adjusting parameters under various error conditions and evaluating the results, the system identifies optimal parameters that prevent oscillation during actual production operations
Solution Approach 2:
The patent implements a feedback mechanism where the control device monitors robot behavior and work quality during parameter adjustment trials. Based on feedback from multiple error conditions, the system iteratively refines parameters to eliminate oscillation issues before production deployment
3Device complexity
If force control parameters are not checked on multiple position and posture error conditions, then the checking process is simplified, but the searching may fail during production
Solution Approach 1:
The patent segments the checking process into multiple independent verification steps, each targeting specific error conditions. The control device checks parameter effectiveness separately for different position and posture error scenarios, ensuring comprehensive validation without overwhelming complexity
Solution Approach 2:
The patent performs parameter checking under more error conditions than the minimum single condition, applying partial checks for each error type. This excessive action ensures that parameters are robust enough to handle unexpected variations during production, preventing work failure
Data Source
AI summary
The present invention makes it possible, in force control during production, to automatically adjust a force control parameter optimally so as not to cause oscillation of a robot or failure of work. This robot system comprises: a robot arm having a hand at the end thereof for holding a workpiece; a force detector for detecting a force and moment received by the workpiece held by the hand; and a control device for moving the workpiece held by the hand with respect to a target object while performing force control of the robot arm to correct a position error and an attitude error of the workpiece, on the basis of a predetermined force control parameter and a detected value of the force detector. The control device has a parameter automatic adjustment unit for automatically adjusting the force control parameter by executing the moving of the workpiece with respect to the target object a plurality of times. The parameter automatic adjustment unit automatically adjusts the force control parameter by executing the moving of the workpiece with respect to the target object from a plurality of attitude error directions among a plurality of position error directions and the plurality of attitude error directions.