Robot Arm Deflection Correction Under Changing Tool Loads
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Solution Overview
Problem
Existing robot control methods face challenges in maintaining absolute position accuracy due to elastic deformation of speed reducers and bearings, especially when the load attached to the robot arm changes, requiring manual correction and increased work effort.
Innovation Solution
A robot control method that calculates gravitational torque and deflection based on load information, adjusts correction amounts according to collision sensitivity, and modifies operation programs in real-time to ensure accurate deflection correction, even when the load changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If deflection correction is performed using fixed teaching data, then the robot can operate with predetermined trajectories, but the position accuracy deteriorates when the load changes
Solution Approach 1:
The patent implements dynamic deflection correction by continuously updating the deflection amount based on actual load torque measurements during operation. The correction value is adjusted in real-time according to the difference between current and teaching load conditions, transforming the static correction approach into a dynamic adaptive system that maintains accuracy under varying loads
Solution Approach 2:
The system measures actual load torque during operation and uses this feedback to calculate and apply appropriate deflection corrections. The control device compares current load conditions with teaching data and automatically adjusts the correction amount, creating a closed-loop feedback mechanism that maintains position accuracy without manual intervention
2Manufacturing precision
If manual correction is performed every time load torque changes, then position accuracy can be maintained, but the work amount increases
Solution Approach 1:
The robot system performs self-correction of deflection by automatically measuring its own load torque, calculating the appropriate correction amount based on stored teaching data, and applying the correction without external intervention. This eliminates the need for manual correction operations while maintaining position accuracy
Solution Approach 2:
The system stores deflection correction data during the teaching phase for various load conditions. When operation begins, the appropriate correction data is already prepared and can be immediately applied based on the actual load, eliminating the need for time-consuming manual correction calculations during production
3Reliability
If high collision sensitivity is used to detect collisions quickly, then safety improves, but false detection increases when load information is inaccurate
Solution Approach 1:
The system dynamically adjusts the collision detection threshold based on the accuracy of load information. When load conditions are well-established and accurate, the threshold is set lower for high sensitivity. When load conditions are uncertain or changing, the threshold is adjusted to prevent false detections, optimizing the balance between safety and false alarms
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method effectively corrects arm deflection in real-time, ensuring the robot moves along the target path accurately, reducing manual intervention and operational inefficiencies.
Implementation Method 1
calculating gravitational torque to be applied to the joint portion based on the load information
Implementation Method 2
the speed reducer and a bearing are elastically deformed and an arm is deflected
Data Source
AI summary
Load information on a tool to be attached to a robot arm and collision sensitivity are input. Gravitational torque is calculated based on the input load information. A deflection amount of the robot arm is calculated based on the gravitational torque. A correction amount is calculated based on the collision sensitivity input. The deflection amount is corrected while the robot arm moves.