Robot Arm Speed Deceleration Before Safety Monitoring Activation
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Solution Overview
Problem
Existing robot systems face frequent interruptions due to excessive motor speed, leading to inefficient production processes, as they are designed to stop the industrial machine when the motor speed exceeds a threshold, without a method to reduce speed effectively before stopping.
Innovation Solution
A control method and system that detects the moving speed of a robot arm, decelerates it to below the set speed limit when a safety input signal is received, and enables speed monitoring after a predetermined switching time, preventing forced stops and reducing operational interruptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the robot arm is stopped forcibly when speed exceeds the threshold, then safety is ensured, but production efficiency deteriorates due to frequent interruptions
Solution Approach 1:
The control unit performs preliminary deceleration of the robot arm when speed approaches the threshold, preventing the speed from exceeding the limit in the first place. This anticipatory action avoids triggering the forced stop by the functional safety unit, thereby maintaining both safety and production continuity
Solution Approach 2:
The control unit acts as an intermediary between the robot arm and the functional safety unit. It monitors speed and intervenes by decelerating the robot arm before the functional safety unit would trigger a forced stop, thus mediating between safety requirements and production efficiency
2Productivity
If the robot arm decelerates smoothly before speed limit, then operational continuity is maintained, but response time increases
Solution Approach 1:
The control unit applies partial deceleration only when necessary (when speed approaches the threshold), rather than continuous deceleration. This partial action maintains operational continuity while minimizing the time lost to deceleration
Data Source
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AI summary
In a control method for controlling a robot system including a robot arm, a control unit configured to control an operation of the robot arm, and a functional safety unit configured to forcibly stop the operation of the robot arm when a speed monitoring function of the robot arm is enabled and a moving speed of the robot arm exceeds a set speed limit, the method includes: detecting, by the control unit, the moving speed of the robot arm; decelerating, by the control unit, the moving speed to less than the speed limit when a predetermined condition including that the moving speed exceeds the speed limit is satisfied in a case in which a safety input signal that enables a speed limit from a safety input device is received; and enabling, by the functional safety unit, the speed monitoring function when a switching time elapses after receiving the safety input signal.