Robot Direct Teaching Control Near Motion Boundaries
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Solution Overview
Problem
Direct teaching methods for industrial robots often result in reduced usability due to excessive load and difficulty in moving away from operation-prohibited ranges, as the feel of the robot becomes heavy near boundaries, leading to complicated operations and potential collisions with peripheral devices.
Innovation Solution
A method that sets a proximity region within the operation-allowed range, stores the external force applied when the monitoring point reaches this region as a reference, and compares it with the current external force to determine a direction facilitating movement away from the proximity region, thereby restricting movement towards the operation-prohibited range and allowing easier exit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the feel of the robot is made heavier near the boundary of the operation-allowed range to prevent operation errors, then the robot can recognize that an operation-prohibited range is being approached, but the usability in the proximity region is reduced and moving away from the proximity region becomes difficult
Solution Approach 1:
The patent applies different control characteristics to different spatial regions: in the proximity region near the boundary, the control provides tactile feedback only in the direction toward the boundary (making movement feel heavier only in that direction), while allowing free movement in other directions. This local differentiation resolves the contradiction by providing safety feedback where needed without restricting usability in safe directions.
Solution Approach 2:
The control characteristics dynamically change based on the robot's position and movement direction. When the robot is in the proximity region and moving toward the boundary, the control increases resistance. When moving away from the boundary or in safe directions, the control returns to normal characteristics. This dynamic adjustment resolves the contradiction by adapting the heaviness of the feel to the specific operational context.
2Reliability
If the feel of the robot is made heavier when approaching the boundary to prevent operation errors, then safety is improved, but the operation becomes complicated requiring another control device to move the arm back into the operation-allowed range
Solution Approach 1:
The control device enables the operator to self-correct the robot's position by providing tactile feedback that guides movement back into the operation-allowed range. The asymmetric resistance in the proximity region naturally guides the operator to move the robot in safe directions, eliminating the need for separate control devices or complex procedures to recover from boundary approaches.
3Reliability
If the range of motion of the articulation is reduced for safety reasons in collaborative robots, then safety is improved, but there are many situations where it is necessary to move the arm at the proximity of the boundary or to move the arm away from the proximity of the boundary during direct teaching
Solution Approach 1:
The patent applies asymmetric control characteristics specifically in the proximity region near the boundary, rather than uniformly restricting all movements. This allows the robot to maintain reduced range of motion for safety while providing enhanced tactile feedback only where needed, enabling operators to perform direct teaching operations at and near boundaries with appropriate guidance.
Solution Approach 2:
The control system provides tactile feedback to the operator when the robot approaches the boundary, guiding the operator's movements. This feedback mechanism enables operators to understand the spatial constraints and perform teaching operations more effectively within the reduced range of motion, improving adaptability without compromising safety.
Data Source
AI summary
A method and apparatus for controlling a robot is provided. In this robot, direct teaching can be performed while updating a position command on the basis of an applied external force. In the method and apparatus, a proximity region is set inside a boundary of an operation-allowed range of the robot, the proximity region being indicative of a proximity of the boundary. Stored is an external force applied when a monitoring point provided in the robot reaches the proximity region as a reference external force. And performed is comparing the reference external force with a current external force when a current position of the monitoring point is in the proximity region, to thereby determine a direction that facilitates movement away from the proximity region.