Wearable Robot Arm Synchronization via Virtual Spring-Damper Control
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Solution Overview
Problem
Existing muscle force assistive wearable robots face challenges in synchronizing two arms when lifting heavy weights, leading to arm imbalance and increased wearer fatigue, as they require separate movement to maintain arm levelness and balance.
Innovation Solution
A method involving a finding-out step to determine position differences between the arms, a generating step to create virtual forces using a virtual spring-damper model, and a converting step to convert these forces into driving torque for the joints using a Jacobian matrix, allowing for synchronized arm movement and level adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If existing muscle force assistive wearable robots control two arms separately to reflect wearer intention, then each arm can move independently according to wearer intent, but the arms cannot be synchronized when lifting heavy weights, leading to imbalance and increased wearer fatigue
Solution Approach 1:
The control device calculates position differences between the two arms and generates virtual forces based on these differences, creating a feedback mechanism that automatically adjusts arm positions to maintain synchronization and balance when lifting heavy weights
Solution Approach 2:
A virtual spring-damper model is introduced as an intermediary element between the two arms. This virtual model generates reacting forces that mediate the interaction between arms, enabling automatic synchronization without requiring additional physical sensors or direct mechanical coupling
2Stability of the object's composition
If the wearer manually keeps the arms level by separately moving each arm, then arm levelness can be maintained, but the wearer experiences large amounts of fatigue
Solution Approach 1:
The control system enables the robot arms to self-correct their positions automatically. The control device monitors position differences and generates appropriate virtual forces to maintain arm levelness without requiring continuous manual adjustment by the wearer, thereby reducing wearer energy expenditure and fatigue
Solution Approach 2:
The system continuously monitors arm positions and provides automatic feedback control through virtual forces, eliminating the need for manual intervention to maintain arm levelness and reducing the physical burden on the wearer
3Reliability
If heavy weight is inclined to one side during lifting, then the arm balance is rapidly broken, but the existing control methods cannot synchronize the arms to prevent this inclination
Solution Approach 1:
The control device continuously calculates position differences between arms and generates virtual forces to counteract any inclination. This feedback mechanism detects balance deviations and automatically applies correcting forces to maintain arm synchronization and prevent weight inclination, enhancing lifting stability
Solution Approach 2:
The virtual spring-damper model generates preemptive reacting forces that counteract potential imbalance before it occurs. By continuously monitoring position differences and applying corrective virtual forces, the system prevents arm inclination and maintains balance proactively rather than reactively
Data Source
AI summary
A method of controlling two arms of a robot including: a finding-out step of finding out position differences in axial directions of an end of one arm and an end of the other arm; a generating step of generating a virtual force at the end of the other arm based on the position differences that have been found out; and a converting step of converting the generated virtual force into a driving torque for joints of the other arm, using a Jacobian matrix.