Robot Arm Control via Geometric Correction Values
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Solution Overview
Problem
Industrial robot arms often deviate from their theoretical representations due to manufacturing variability, leading to inaccuracies in trajectory execution when using predefined Cartesian coordinates, requiring complex recalibration and specific knowledge of actual geometrical parameters for control program development.
Innovation Solution
A method for controlling an automated work cell that calculates articular instruction correction values based on nominal and actual geometrical parameters, allowing for accurate positioning and orientation without prior knowledge of the robot arm's actual parameters, simplifying control program development and enabling compatibility across different robot arms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If calibration methods are used to determine actual geometric parameters, then positioning precision is improved, but control program complexity increases
Solution Approach 1:
The patent introduces an intermediary correction mechanism that operates between the nominal inverse kinematic model and the actual robot arm. Instead of requiring the control program to directly handle complex actual geometric parameters, the system computes correction values that bridge the gap between theoretical and actual geometries. This intermediary approach maintains simple control program structure while achieving high positioning precision.
Solution Approach 2:
The patent segments the correction process into distinct components: nominal articular instructions from the theoretical model, correction values derived from actual geometric parameters, and effective articular instructions as the final output. This segmentation allows the control program to remain simple while systematically accounting for geometric deviations through modular correction steps.
2Manufacturing precision
If actual geometrical parameters are integrated into control center programs, then trajectory accuracy is improved, but program development difficulty increases
Solution Approach 1:
The patent extracts the complexity of handling actual geometric parameters from the control center program and relocates it to a separate correction calculation module. The control center program continues to use simple nominal parameters, while the extraction of geometric deviations is handled by computing correction values based on actual parameters stored separately. This separation maintains trajectory accuracy while simplifying program development.
3Measurement precision
If complex inversion calculations are implemented to account for parameter deviations, then positioning accuracy is improved, but computational resource consumption increases
Solution Approach 1:
The patent applies partial correction by computing adjustment values that are sufficient to compensate for geometric deviations without implementing full complex inversion calculations in the control center. The correction values provide just enough adjustment to achieve accurate positioning while avoiding the excessive computational burden of complete re-inversion with actual parameters.
Data Source
AI summary
This method of controlling an automated work cell provided with a robot arm comprises the steps of:a) calculating Cartesian instructions corresponding to the nominal articular instructions;b) calculating actual articular instructions from the Cartesian instructions, taking into account actual geometrical parameters of the robot arm;c) calculating for each nominal articular instruction and from the actual articular instruction, an articular instruction correction value;d) calculating, for each nominal articular instruction and from the calculated articular correction instruction, an effective articular instruction;e) calculating control instructions for each motor controller from the calculated effective articular instructions;f) transmitting the motor control instructions to each motor controller.