Robot Joint Control for Manual Guidance Near Motion Limits
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Solution Overview
Problem
Current robot control methods lack effective integration of manual guidance and position control, particularly in complex joint movements, leading to inefficiencies and potential collisions with end stops.
Innovation Solution
A method and system that utilize joint position sensors and drives to assist or resist manual guidance based on specified limits and spacings, allowing for differential impedance control without rapid force detection, and project target joint positions to minimize spacing between a robot and a fixed point, thereby enhancing manual guidance and preventing collisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If manual guidance of robot joints is implemented without assistance, then the robot can be easily controlled by human operators, but the robot may collide with end stops and fail to maintain precise positioning
Solution Approach 1:
The control system continuously detects current joint positions and compares them with specified limits, then dynamically adjusts drive assistance based on the spacing to limits. This closed-loop feedback mechanism prevents collisions by reducing assistance when approaching limits while maintaining ease of operation within safe boundaries.
Solution Approach 2:
The drive assistance is made dynamic rather than static - it automatically adjusts the level of support provided to manual guidance based on real-time joint position and proximity to limits. This dynamic adaptation allows easy operation when safe while preventing collisions when approaching boundaries.
2Productivity
If drive assistance is strongly applied to assist manual guidance movements, then the robot responds more readily to operator input, but the robot may exceed specified joint position limits and collide with end stops
Solution Approach 1:
The control system changes the parameter of drive assistance strength based on joint position parameters. When spacing to limits is large, assistance is strong for fast response; when spacing decreases, assistance is reduced to maintain precision and prevent limit violations. This parameter adaptation resolves the contradiction between speed and accuracy.
3Reliability
If software-based end stops with differential impedance control are implemented, then collision prevention is improved, but the control system complexity increases
Solution Approach 1:
Physical mechanical end stops are replaced with software-based virtual end stops that use differential impedance control. This substitution eliminates complex mechanical limit structures while achieving collision prevention through intelligent control algorithms, reducing overall device complexity despite increased software sophistication.
4Adaptability or versatility
If the robot uses at least six joints to depict a wide range of positions and orientations, then the robot's versatility and positioning capability are improved, but the complexity of controlling each joint within limits increases
Solution Approach 1:
A single automated control system is designed to universally manage all six or more joints simultaneously. Rather than implementing separate control mechanisms for each joint, the system applies differential impedance control across all joints based on their respective positions and limits, reducing overall control complexity while maintaining full versatility.
Data Source
AI summary
A method for controlling a robot includes detecting current positions of joints of the robot and actuating the joints using drives of the robot based on the detected current joint positions such that at least one drive supports a manual guidance-induced movement of the joint actuated by the drive if a distance between the detected or target joint position and a specified first boundary has a first value. The drive supports the manual guidance-induced movement to a lesser degree if the distance has a second value which is lower than the first value. Additionally, the manual guidance-induced movement is oriented towards the first boundary.