Robot Orientation Control for Multi-Robot Load Handling
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Solution Overview
Problem
When multiple robots carry a load, their interference reduces the working volume and leads to over-constraint, causing singularities that can result in the load being broken or robots straining due to trying to control all 6 degrees of freedom, limiting their movement and increasing the risk of errors.
Innovation Solution
A method that allows robots to ignore one of the three prescribed tool center point orientation values, finding new orientation values that place the wrist center point closest to the base while maintaining the original location values, using joints like universal, ball and socket, or hinge joints to relax orientation requirements, thereby increasing the working volume and reducing over-constraint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple robots carry a load with fixed orientation control, then the load position can be precisely controlled, but the working volume is reduced due to robot interference and over-constraint
Solution Approach 1:
The invention changes the control parameters from fixed 6-DOF orientation control to relaxed orientation control where only 3-4 DOF are actively controlled. By modifying the control approach from precise orientation fixing to position-focused control with flexible orientation, the robots can operate in a larger volume without compromising load position accuracy
Solution Approach 2:
Instead of fully controlling all 6 DOF of each robot, the invention applies partial action by controlling only the necessary DOF for position accuracy while allowing other DOF to be more flexible. This reduces the constraint on robot movement and increases working volume
2Measurement precision
If robots control all 6 degrees of freedom, then the load orientation is precisely maintained, but the robots experience over-constraint and singularities causing strain and potential failure
Solution Approach 1:
The invention extracts the orientation control requirement from the rigid 6-DOF constraint and separates it from the position control. By taking out the fixed orientation requirement and allowing flexible orientation, the system maintains position precision while reducing strain on robots and eliminating singularity-related reliability issues
Solution Approach 2:
The invention introduces dynamics by allowing the load orientation to adapt rather than remain fixed. The orientation becomes a dynamic parameter that can adjust to robot capabilities and positions, preventing over-constraint and singularity conditions that would compromise reliability
3Adaptability or versatility
If robots are located in different positions, then the system achieves better coverage, but the intersection of working volumes reduces the effective working volume
Solution Approach 1:
The invention makes each robot capable of contributing to multiple functions by allowing flexible orientation and position adjustments. Each robot can adapt its configuration to serve different roles in the load manipulation, maximizing the effective use of the intersection volume while maintaining broad system coverage
Data Source
AI summary
A method for controlling a robot during an interpolation of a trajectory or motion to any prescribed position, comprises the steps of a) ignoring at least one of the three originally prescribed or interpolated tool center point orientation values; b) finding new tool center point orientation values that place the wrist center point of the robot closest to its base while c) maintaining the originally prescribed or interpolated tool center point location values and d) maintaining the original prescribed or interpolated tool center point orientation values not ignored. Said method can preferably be used for carrying a load with a plurality of robots. Its main advantage is an increase of the available working volume.