Coupled Admittance Controllers With Lagrange-Multiplier Force Coupling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing admittance control technologies are limited to specific initial conditions and do not allow for specialized coupling behaviors such as break-out simulation, and are not flexible in configuring multiple actuators.
Innovation Solution
The use of modified Lagrange multipliers to calculate a virtual force within the admittance control loop, combined with virtual springs and dampers, allows for flexible coupling configurations and simulation of break-out conditions, enabling robust coupling of actuators even with differing initial conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional admittance control is used to couple actuators, then the control is simple to implement, but it is only valid for specific initial conditions and does not allow for specialized coupling behaviors
Solution Approach 1:
The patent introduces Lagrange multipliers as intermediary variables that mediate between multiple admittance controllers. These multipliers act as virtual coupling forces that enforce constraints between actuators while allowing each controller to maintain its independent admittance control structure. This resolves the contradiction by providing versatile coupling behavior through the intermediary Lagrange multipliers without fundamentally changing the simplicity of individual admittance controllers.
Solution Approach 2:
The patent modifies the traditional admittance control by adding Lagrange multiplier terms to the force equations. This parameter change allows the system to transition from fixed initial condition requirements to flexible coupling behaviors. The Lagrange multipliers dynamically adjust the coupling forces based on constraint violations, enabling specialized behaviors like break-out simulation while maintaining the core admittance control parameter structure.
2Adaptability or versatility
If modified Lagrange multipliers are used to calculate virtual force, then specialized coupling behaviors like break-out simulation are enabled, but the calculation complexity increases
Solution Approach 1:
The modified Lagrange multiplier implementation uses feedback from constraint violations to adjust coupling forces. The system continuously monitors position and force differences between coupled actuators and adjusts the Lagrange multiplier values accordingly. This feedback mechanism enables specialized behaviors like break-out simulation where coupling forces are capped at certain thresholds, while keeping calculations manageable through iterative adjustment rather than complex closed-form solutions.
3Reliability
If virtual springs and dampers are added to the coupling, then initial condition problems are solved and coupling becomes more robust, but the system complexity increases
Solution Approach 1:
The patent incorporates virtual springs and dampers as cushioning elements in the coupling system. These elements provide beforehand cushioning by introducing compliant coupling that gradually adjusts to initial condition differences between actuators. The virtual spring absorbs position mismatches while the virtual damper dissipates velocity differences, preventing abrupt coupling shocks and enabling robust coupling even when actuators start from different initial conditions. This approach maintains reliability without requiring complex control algorithms.
Data Source
Figure 1~2
Figure 3
Figure 4
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.