Collaborative Robot Controller Conveyor Stop Safety
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Solution Overview
Problem
Collaborative robots and workpieces are at risk of damage, and operators may be injured when conveyors suddenly stop or accelerate, as existing safety measures do not adequately prevent collisions between robots, workpieces, and humans in shared working areas.
Innovation Solution
A robot controller that issues stop commands to collaborative robots, allowing them to move at different velocities relative to the conveyor based on their position relative to the workpiece, increasing the coasting distance when positioned anteriorly and decreasing it when positioned posteriorly to the workpiece, thereby lengthening the distance between the robot and the workpiece during conveyor stoppage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the robot stops immediately when the conveyor starts stop motion, then the robot response time is improved, but the workpiece may collide with the stopped robot causing damage
Solution Approach 1:
The robot controller detects the conveyor's deceleration state in advance and commands the robot to move away from the workpiece before the conveyor fully stops. This preliminary action ensures that when the conveyor stops, the robot is already positioned at a safe distance, preventing collision while maintaining fast response.
Solution Approach 2:
The system applies a counteracting force by moving the robot in the opposite direction of the workpiece motion when the conveyor decelerates. This preliminary anti-action creates separation between the robot and workpiece, preventing the harmful collision effect before it can occur.
2Ease of operation
If the robot moves at the same velocity as the conveyor, then the robot can perform operations on the workpiece, but the operator may be sandwiched between the workpiece and robot when conveyor stops
Solution Approach 1:
The robot velocity is made dynamic rather than constant. The controller continuously adjusts the robot's velocity based on the conveyor's motion state. When the conveyor decelerates, the robot velocity is reduced more aggressively than the conveyor velocity, creating a velocity differential that increases the distance between robot and workpiece, thereby protecting the operator.
Solution Approach 2:
The robot controller receives feedback from the conveyor controller about the conveyor's deceleration state and continuously adjusts the robot's motion in response. This feedback mechanism ensures the robot velocity is optimized in real-time to maintain safety margins while preserving operational capability.
3Object-affected harmful factors
If the robot velocity is reduced when conveyor decelerates, then operator safety is improved, but the robot may not be able to complete operations on the workpiece
Solution Approach 1:
The robot's motion control is segmented into different phases: during normal operation, the robot maintains velocity matched to the conveyor for efficient work; when the conveyor decelerates, the robot transitions to a separate deceleration phase with higher deceleration rate to create safety distance. This segmentation allows the system to optimize for both productivity and safety at different times.
Data Source
AI summary
A robot controller and a robot control method, capable of preventing an operator from being sandwiched between a robot and a workpiece, when a conveyor for conveying the workpiece is stopped. The robot controller is configured to output a robot stop command when a conveyor starts the stop operation thereof. The robot stop command includes at least one of: a first stop command by which, when a movable section of the robot is positioned anterior to the workpiece, the movable section is moved at a higher velocity than the conveyor, and then is stopped after traveling a distance longer than a coasting distance of the conveyor; and a second stop command by which, when the movable section is positioned posterior to the workpiece, the movable section is moved at a lower velocity than the conveyor, and then is stopped after traveling a distance shorter than the coasting distance.