Robot Wrist Angle Correction for Stroke Limit Avoidance
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Solution Overview
Problem
Existing robot systems face challenges when the rotation angle of the wrist approaches a stroke limit during picking operations, leading to potential error stops and interference with workpieces or peripheral objects.
Innovation Solution
A robot system with a 360° or more operating range distal-end wrist axis, equipped with a sensor to detect workpiece position and orientation, and a controller that adjusts the wrist axis angle by 360° when it exceeds the operating limit, ensuring the angle remains within the operating range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the wrist is rotated in a direction in which the rotation angle approaches 0° when the distance between workpieces is large, then the picking operation can be performed, but the rotation angle of the wrist approaches a stroke limit
Solution Approach 1:
The system changes the rotation parameter of the distal-end wrist axis by adding or subtracting 360° to shift the angle to a different representation within the operating range. This allows the wrist to maintain the same physical orientation while avoiding stroke limits, enabling continuous operation without error stops.
2Productivity
If the robot performs picking operations with limited wrist rotation range, then the operation can be completed, but error stops occur when the wrist axis approaches its limits
Solution Approach 1:
The system dynamically adjusts the rotation angle representation of the distal-end wrist axis based on the current angle and operating limits. By continuously monitoring and shifting the angle by 360° when approaching limits, the system maintains operational continuity and prevents error stops while completing picking operations.
3Device complexity
If the wrist rotation angle is not adjusted, then the operation program is simple, but the tool interferes with workpieces or peripheral objects
Solution Approach 1:
The system changes the angle parameter of the distal-end wrist axis by adding or subtracting 360° to achieve a different rotational representation that avoids tool interference with workpieces or peripheral objects, while maintaining the same physical tool orientation and position.
Data Source
AI summary
A robot system including an articulated robot equipped with a tool attached to a distal-end wrist axis, a sensor that detects a position and an orientation of the workpiece, and a controller configured to control the robot based on an operation program. The operation program includes two or more teaching points, each of which defines a position and an orientation of the tool, and an operation instruction. The controller is configured to correct the position and the orientation of the tool at a first teaching point based on the detected position and the orientation, determine whether an angle of the distal-end wrist axis at the first teaching point after correction exceeds an operating limit, and when it is determined that the operating limit is exceeded, change the angle, at the first teaching point, to an angle to be within the operating range by increasing or decreasing the angle.