Robot Moment Vector Correction for Friction-Limited Grounding
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Solution Overview
Problem
Existing robots struggle to adjust the floor reaction force moment effectively, particularly when it exceeds the frictional limit, leading to potential instability and falling due to insufficient floor reaction force moment compensation.
Innovation Solution
A robot equipped with a calculation unit that calculates the floor reaction force moment around the vertical axis from the center of gravity and a moment vector orbit, and a control unit that corrects the moment vector around the center of gravity to adjust the floor reaction force moment, minimizing the correction amount to prevent ZMP fluctuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the floor reaction force moment is adjusted only by arm swing force, then the control mechanism is simple, but the floor reaction force moment cannot be adequately adjusted when it exceeds the frictional limit
Solution Approach 1:
The system dynamically switches between two control modes: when the floor reaction force moment is within the frictional limit, only arm swing control is used; when it exceeds the limit, the system transitions to correcting the moment vector around the center of gravity. This dynamic adaptation resolves the contradiction by adjusting the control mechanism's complexity only when necessary to maintain reliability.
Solution Approach 2:
The system changes the control parameter from arm swing force alone to a corrected moment vector around the center of gravity when the floor reaction force moment exceeds the frictional limit. This parameter change enables adequate adjustment of the floor reaction force moment while maintaining simplicity when the simpler method suffices.
2Reliability
If the moment vector around the center of gravity is corrected to adjust floor reaction force moment, then the floor reaction force moment adjustment capability is improved, but the ZMP may fluctuate causing instability
Solution Approach 1:
The system continuously monitors the floor reaction force moment and compares it against the frictional limit. When the moment exceeds the limit, feedback triggers the moment vector correction around the center of gravity. This feedback mechanism ensures that ZMP stability is maintained by only activating correction when necessary and using the minimal required correction amount.
Solution Approach 2:
The system calculates the correction amount of the moment vector in advance to minimize the norm, thereby preventing excessive correction that would cause ZMP fluctuation. This preliminary calculation of the minimal necessary correction maintains stability while achieving the required floor reaction force moment adjustment.
3Stability of the object's composition
If the correction amount of the moment vector is minimized, then the ZMP stability is maintained, but the floor reaction force moment adjustment range is limited
Solution Approach 1:
The system dynamically selects the appropriate control strategy based on the current state. When minimal correction suffices, it maintains ZMP stability; when larger adjustments are needed, it activates the moment vector correction around the center of gravity. This dynamic selection resolves the contradiction between minimizing correction and maintaining adequate adjustment range.
Data Source
AI summary
A robot that moves on a leg, the robot comprising: a calculation unit that calculates a floor reaction force moment around a vertical axis from a center of gravity and a ZMP trajectory of the robot and a moment orbit around the center of gravity, and obtains a correction amount of a moment vector around the center of gravity when the floor reaction force moment around the vertical axis exceeds a frictional limit; and a control unit that controls the robot based on the correction amount.