Industrial Robot Motion Planning for Dynamic Obstacle Avoidance
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Solution Overview
Problem
Existing dynamic motion planning systems for industrial robots suffer from feedback delays, numerical instability, insensitivity to static obstacles, and computational complexity, particularly in handling dynamic obstacles and robot parts other than the end-of-arm tool.
Innovation Solution
A decoupled motion planning and obstacle avoidance system that computes a commanded robot path using a simplified safety function incorporating both relative position and velocity of obstacles, performed in a feedback loop separate from the robot controller's feedback loop, allowing real-time adjustments and efficient collision avoidance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single closed-loop feedback system is used for both robot motion control and obstacle avoidance, then the system is logically simple, but feedback delays occur due to highly coupled and conflicting inputs and feedback loops
Solution Approach 1:
The patent divides the control system into two separate feedback loops: an inner loop for real-time robot motion control and an outer loop for obstacle avoidance planning. This segmentation allows each loop to operate independently with its own optimization criteria, eliminating the feedback delays caused by coupled conflicting inputs while maintaining logical coherence through hierarchical coordination.
2Reliability
If complex safety function formulations are used for collision avoidance, then comprehensive obstacle avoidance is achieved, but numerical instability issues and computational complexity leading to slowness occur
Solution Approach 1:
The patent extracts the obstacle avoidance constraint from the complex coupled system and formulates it as a separate inequality constraint in the outer planning loop. This extracted constraint focuses specifically on maintaining safe distances from obstacles using a simplified relative position and velocity model, removing numerical instability sources while preserving collision avoidance reliability.
Solution Approach 2:
The patent changes the safety function formulation from complex coupled parameters to simplified relative position and velocity parameters between robot and obstacles. This parameter transformation reduces computational complexity and improves calculation speed while maintaining the essential collision avoidance functionality through the inequality constraint.
3Adaptability or versatility
If existing dynamic motion planning systems are used, then obstacle avoidance is attempted, but insensitivity to static obstacles and inability to consider robot parts other than end-of-arm tool occur
Solution Approach 1:
The patent creates a universal obstacle avoidance constraint that works for both static and dynamic obstacles, as well as for any robot part (not just the end-of-arm tool). The inequality constraint formulation using relative position and velocity is universally applicable to any robot-link-obstacle configuration, providing comprehensive and reliable obstacle detection and avoidance across all scenarios.
Data Source
AI summary
A method and system for dynamic collision avoidance motion planning for industrial robots. An obstacle avoidance motion optimization routine receives a planned path and obstacle detection data as inputs, and computes a commanded robot path which avoids any detected obstacles. Robot joint motions to follow the tool center point path are used by a robot controller to command robot motion. The planning and optimization calculations are performed in a feedback loop which is decoupled from the controller feedback loop which computes robot commands based on actual robot position. The two feedback loops perform planning, command and control calculations in real time, including responding to dynamic obstacles which may be present in the robot workspace. The optimization calculations include a safety function which efficiently incorporates both relative position and relative velocity of the obstacles with respect to the robot.