Robot Velocity Attenuation for Collision-Free Path Tracking
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Solution Overview
Problem
Existing robotic motion planning techniques struggle to dynamically reduce robot speed to avoid collisions with static or dynamic obstacles while maintaining the planned tool path.
Innovation Solution
A method and system for robotic motion planning that perform dynamic velocity attenuation by providing feedback of a computed slowdown ratio to a tracking controller, ensuring path synchronization with current robot speed, and using robot-obstacle distance and relative velocity to determine when to apply velocity attenuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the robot stops when an obstacle is detected within threshold distance, then collision avoidance is achieved, but productivity deteriorates due to frequent stopping
Solution Approach 1:
The patent implements dynamic velocity attenuation by continuously adjusting the robot's speed based on real-time obstacle detection and relative velocity calculations, rather than using fixed stop/go decisions. The controller dynamically computes a velocity attenuation factor that scales the robot's velocity command, allowing smooth speed transitions that maintain productivity while ensuring collision avoidance through continuous motion adaptation.
Solution Approach 2:
The patent changes the velocity parameter dynamically by computing a velocity attenuation factor based on obstacle distance, obstacle velocity, and robot kinematics. This parameter modification allows the robot to operate at reduced speeds near obstacles rather than complete stops, maintaining operational efficiency while achieving reliable collision avoidance through continuous parameter adaptation.
2Reliability
If the robot reduces speed to avoid obstacles, then collision avoidance is improved, but path tracking precision deteriorates due to speed-synchronization issues
Solution Approach 1:
The patent implements a feedback mechanism where the computed velocity attenuation factor is fed back to the tracking controller, which then adjusts the velocity commands to maintain synchronization between the robot's actual speed and the programmed path parameters. This feedback loop ensures that even when speed reduction is necessary for obstacle avoidance, the robot remains synchronized with the intended tool path, maintaining path tracking precision.
3Reliability
If safety zones are pre-programmed to prohibit robot movement, then collision avoidance is ensured, but device complexity increases due to additional programming and workspace restrictions
Solution Approach 1:
The patent replaces static pre-programmed safety zones with dynamic velocity attenuation that adapts in real-time to actual obstacle positions and motions. Instead of defining fixed prohibited geometric zones that restrict workspace, the system continuously computes velocity adjustments based on current robot-obstacle relative velocity and distance, reducing programming complexity while maintaining or improving collision avoidance effectiveness.
Data Source
AI summary
A method and system for robotic motion planning which perform dynamic velocity attenuation to avoid robot collision with static or dynamic objects. The technique maintains the planned robot tool path even when speed reduction is necessary, by providing feedback of a computed slowdown ratio to a tracking controller so that the path computation is always synchronized with current robot speed. The technique uses both robot-obstacle distance and relative velocity to determine when to apply velocity attenuation, and computes a joint speed limit vector based on a robot-obstacle distance, a maximum obstacle speed, and a computed stopping time as a function of the joint speed. Two different control structure implementations are disclosed, both of which provide feedback of the slowdown ratio to the motion planner as needed for faithful path following. A method of establishing velocity attenuation priority in multi-robot systems is also provided.