Robot Posture Constraint Control Near Singularities
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Solution Overview
Problem
Existing robot control systems struggle to accurately position an end effector at a designated point in a real working space when the actual environment differs from the simulated environment, potentially leading to posture limits or singularities.
Innovation Solution
A robot control system that calculates a degree of margin from a simulated posture to a limit posture, determines a constraint condition for drive axes, and adjusts the robot's posture based on this margin to ensure accurate positioning despite environmental discrepancies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the robot executes a simulated posture based on a robot model in a virtual environment, then the robot can be controlled to reach a designated point, but the actual positioning accuracy deteriorates when the real environment differs from the simulated environment
Solution Approach 1:
The system performs preliminary simulation of robot postures in a virtual environment before actual execution. By calculating multiple candidate postures and evaluating them against constraint conditions in advance, the system prepares optimized motion plans that account for potential environmental variations, thereby improving actual positioning accuracy despite environment mismatches.
Solution Approach 2:
The system calculates a degree of margin indicating how far the simulated posture is from a limit posture, and uses this margin information to determine constraint conditions. This feedback mechanism allows the system to adjust control parameters based on the proximity to singularities or limits, compensating for environmental differences and maintaining positioning accuracy.
2Adaptability or versatility
If the robot operates close to posture limits to achieve complex positioning, then the robot can reach difficult designated points, but the risk of encountering singularities or posture limits increases
Solution Approach 1:
The system preemptively identifies potential singularity problems by calculating the degree of margin from limit postures during simulation. By determining constraint conditions that prevent approaching critical thresholds, the system applies preliminary countermeasures to avoid singularities before they occur, ensuring reliable operation while maintaining positioning capability.
Solution Approach 2:
The system dynamically adjusts constraint conditions based on the calculated degree of margin. When the margin is large, the robot can operate with greater flexibility to reach difficult points. When the margin decreases, constraint conditions are tightened to prevent approaching singularities. This dynamic adaptation maintains both positioning capability and operational reliability.
3Adaptability or versatility
If the robot uses redundant degrees of freedom to reach designated points, then the robot can access more positions, but determining the optimal posture becomes more complex
Solution Approach 1:
The system segments the posture determination process into distinct steps: generating multiple candidate postures, evaluating each against constraint conditions, and selecting the optimal posture. By dividing the complex optimization problem into manageable segments, the system efficiently handles redundant degrees of freedom without overwhelming computational complexity.
Solution Approach 2:
The system changes parameters by calculating a degree of margin for each candidate posture and using this parameter to determine constraint conditions. By transforming the posture selection problem into a parameter-based evaluation and optimization process, the system systematically manages the complexity introduced by redundant degrees of freedom while maximizing reachability.
Data Source
AI summary
A robot system includes: a robot placed in a real working space and having a plurality of drive axes each having a degree of freedom for moving an end effector; and circuitry configured to: set a designated point in a task; virtually execute a simulated posture of the robot at the designated point by a simulation based on a robot model indicating the robot; calculate a degree of margin indicating how far the simulated posture is from a limit posture of the robot; determine a constraint condition of at least one of the plurality of drive axes at the designated point based on the calculated degree of margin; and control the robot based on the constraint condition.