Wearable Robot Joint Control for Hunting Suppression
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Solution Overview
Problem
Wearable robots attached to joint parts of users experience hunting (oscillation) when trying to maintain angles within a given range, leading to user discomfort due to inability to immediately stop joint movements.
Innovation Solution
A method for controlling wearable robots that generates torque at a predetermined angle within the allowable range to maintain stability for a set period, preventing oscillation by balancing user movement torque with motor torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the robot joint is controlled to make the angle go back within the allowable angle range immediately, then the angle constraint is satisfied, but the user cannot stop the joint motion immediately causing hunting (oscillation) at the boundary
Solution Approach 1:
The control method performs preliminary action by maintaining the joint angle at a predetermined position (boundary of allowable range) for a predetermined period before allowing free movement. This advance preparation prevents the hunting phenomenon by ensuring the joint is properly positioned and stabilized before the user's motion continues, thus satisfying both angle constraints and stability requirements.
2Ease of operation
If the control to make the angle go back is ended immediately when the angle reaches the allowable range, then the user can freely operate the joint part, but the angle again exceeds the allowable range due to inability to stop motion immediately
Solution Approach 1:
The system performs preliminary positioning by holding the joint at a predetermined angle (boundary position) for a predetermined period before releasing control. This ensures that when control is ended, the joint starts from a stable position within the allowable range, preventing immediate violation of angle constraints while allowing user freedom of operation.
Solution Approach 2:
The control method implements periodic action by maintaining the joint at a predetermined position for a specific predetermined period of time. This time-based holding strategy ensures proper positioning before releasing control, creating a rhythmic control pattern that balances angle compliance with user operational freedom.
Data Source
AI summary
The method for controlling the wearable robot according to one aspect of the present invention is attached to a joint part of the user, the robot joint being controlled in such a way that, when an angle θ1 of the robot joint (joint part 4) exceeds a predetermined allowable angle range R, the angle θ1 of the robot joint is made to go back within the allowable angle range R. When the robot joint is controlled to make the angle θ1 of the robot joint back within the allowable angle range R and the angle θ1 of the robot joint reaches a predetermined angle θ2, torque is generated in the robot joint to keep the angle θ2 of the robot joint at the predetermined angle θ1 for a predetermined period of time T.