Coupled Admittance Control Using Virtual Force and Break-Out Limits
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Solution Overview
Problem
Current admittance control technologies are limited by assumptions of initial conditions being equal, lack of flexibility in coupling behavior, and inability to simulate break-out behavior, particularly in haptic applications where coupling forces need to be capped.
Innovation Solution
The use of modified Lagrange multipliers to calculate virtual forces within the admittance control loop, allowing for simulation of coupled actuators, addressing initial condition issues and simulating break-out conditions by adding virtual spring and damper components, and capping coupling forces to manage specialized coupling behaviors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard admittance control coupling is used, then basic coupling functionality is achieved, but initial condition differences cause instability and coupling behavior is rigid
Solution Approach 1:
The patent applies parameter changes by modifying the Lagrange multiplier calculation to include virtual spring and damper components. This transforms the rigid coupling into a flexible one where the coupling force is determined by both position and velocity differences, allowing the system to adapt to different initial conditions and simulate various coupling behaviors including break-out conditions.
Solution Approach 2:
The patent introduces virtual spring and damper elements as intermediary components between the coupled actuators. These virtual elements mediate the interaction forces, allowing smooth transition and stabilization when initial conditions differ, while still maintaining the essential coupling functionality.
2Adaptability or versatility
If coupling forces are uncapped, then accurate physical modeling is achieved, but break-out behavior cannot be simulated
Solution Approach 1:
The patent applies dynamics by making the coupling force capability dynamic rather than static. The virtual spring and damper components allow the system to naturally limit coupling forces based on the degree of separation between actuators, enabling break-out behavior simulation while maintaining accuracy within the normal operating range.
3Ease of operation
If virtual mass simulation is used, then remote control coordination is achieved, but initial condition differences cause instability
Solution Approach 1:
The patent applies feedback by continuously monitoring both position and velocity differences between coupled actuators and using this information to dynamically adjust the coupling forces through the virtual spring and damper components. This feedback mechanism stabilizes the system even when initial conditions differ between actuators.
Data Source
AI summary
A coupling device (16, 116, 216, 316) configured optimally to communicate between a first and a second admittance controller and actuator assembly, the first and the second admittance control and actuator assembly respectively having a first and a second admittance controller (12a, 12b) configured to drive a respective first and a second actuator and each of the first and the second actuator being respectively connected to a first body having a first mass and a second body having a second mass, wherein the coupling device (16, 116, 216, 316) comprises: an input port having a first input for receiving a first input force signal (f1) from the first admittance controller and actuator assembly (12a) and a second input for receiving a second input force signal (f2) from the second admittance controller and actuator assembly (12b), and a processor adapted to derive a first output force signal for output to the first admittance controller and actuator assembly based on a Lagrange multiplier dependent on a comparison of the first input force signal and the second input force signal.