Robot Control System for Emergency Stop Coasting Prediction
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Solution Overview
Problem
Existing robot systems face challenges in preventing robots from moving beyond virtual safety barriers due to emergency stops, leading to potential collisions and increased installation costs from mechanical stoppers, which are inefficient in using space.
Innovation Solution
The method involves defining an arm-occupied region and a virtual safety protection barrier, estimating coasting angles during emergency stops, and calculating post-coasting predicted positions to prevent contact with the barrier, thereby ensuring the robot stops before potentially entering the restricted range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a virtual safety barrier is used to restrict robot movement, then installation cost is reduced compared to mechanical stoppers, but the robot may still move beyond the barrier due to coasting after emergency stops
Solution Approach 1:
The system performs preliminary actions by predicting the robot's coasting behavior before it actually occurs. The prediction unit calculates where the robot will coast to after an emergency stop, and the control unit preemptively stops the robot at a calculated position that accounts for this coasting distance, preventing the robot from reaching the virtual safety barrier.
Solution Approach 2:
The system implements feedback by continuously monitoring the robot's state and using the prediction unit to calculate coasting distances based on actual robot parameters. The control unit adjusts the stop position dynamically based on this feedback from the prediction calculations, ensuring the robot stops at the correct position to prevent barrier contact.
2Reliability
If the robot is stopped immediately when predicted position exceeds the virtual safety barrier, then safety is improved, but the robot may stop prematurely even when the actual position would be safe
Solution Approach 1:
The system replaces the simple mechanical comparison of predicted position vs. barrier position with a more sophisticated calculation system. The prediction unit uses robot parameters, velocity, acceleration, and coasting characteristics to calculate the actual stop position, substituting crude mechanical safety checks with refined computational analysis that reduces premature stopping.
3Reliability
If mechanical stoppers are used to prevent robot movement beyond the restricted range, then safety is ensured, but installation cost and space requirements increase
Solution Approach 1:
The system replaces mechanical stoppers with a computational control system. The prediction unit calculates coasting distances and the control unit determines precise stop positions using software-based algorithms instead of physical mechanical barriers, eliminating the need for additional mechanical components while maintaining safety.
Solution Approach 2:
The system creates a virtual model of the robot's coasting behavior through the prediction unit, which replicates and analyzes the coasting phenomenon computationally. This virtual copy of the coasting process allows the system to predict and prevent barrier contact without physical mechanical stoppers.
Data Source
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AI summary
Increased security of robot operation, efficient use of the floor space in a factory or the like, and simplified facilities are achieved. A process includes defining, in a memory, arm-occupied regions (A1, A2, A3, A4, A5, A6) including robot arms (3, 4, 5) and a workpiece (9) and a tool (7) attached to a robot wrist, a virtual safety protection barrier (50) with which the arms are not allowed to come into contact, and a movable range (60) of each robot axis; estimating the coasting angle of each robot axis for which the axis will coast when the robot (1) is stopped due to an emergency stop during execution of a command for moving the robot to a next target position, from an actually measured amount of coasting and the like; determining a post-coasting predicted position of the robot by adding the coasting angles of the axes to the next target position; checking whether or not the arm-occupied regions at the post-coasting predicted position will come into contact with the virtual safety protection barrier, or whether or not the robot axes are within the movable ranges; and performing control to cause the robot to stop moving immediately upon detection of abnormality.