Robotic Joint Control Using Viscous Flow Fields for Safe Guidance
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Solution Overview
Problem
Conventional robotic systems store energy as potential energy due to discrepancies between robot and human motion, leading to sudden movements that can be harmful to the human collaborator during cooperative tasks.
Innovation Solution
A control method for a robotic system that simulates a viscous fluid flow field, applying a total control vector based on error velocity vectors and drag coefficients to guide joints without storing potential energy, ensuring the robotic system moves in sync with the human collaborator without sudden releases of energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional robotic control systems use restoring force to correct position errors, then position accuracy is improved, but potential energy is stored in the controller causing sudden movements that can harm human collaborators
Solution Approach 1:
The patent replaces the conventional mechanical restoring force approach with a virtual viscous flow field model. Instead of applying force proportional to position error (which stores potential energy), the system applies control force proportional to velocity error, simulating viscous drag. This substitution eliminates the spring-like potential energy storage while maintaining guidance capability through the virtual flow field that guides the robot along desired paths.
Solution Approach 2:
The patent changes the fundamental control parameter from position-based feedback to velocity-based feedback. By measuring velocity error rather than position error and applying control force proportional to velocity, the system transforms the control mechanism from potential energy storage (restoring force) to kinetic energy dissipation (drag force), eliminating the harmful spring effect while maintaining guidance.
2Stability of the object's composition
If conventional controllers apply restoring force to maintain desired position, then stability is improved, but energy is stored and can be released suddenly creating safety hazards
Solution Approach 1:
The patent substitutes the conventional elastic restoring force mechanism with a viscous drag-based control mechanism. The virtual flow field applies force proportional to velocity error rather than position error, transforming the energy interaction from potential energy storage and release to continuous kinetic energy dissipation, thereby maintaining stability without storing hazardous energy.
Solution Approach 2:
The patent introduces a virtual viscous flow field as an intermediary between the robot and the desired path. This virtual fluid medium provides continuous guidance through drag forces that dissipate energy rather than store it, acting as a safe mediator that maintains stability while preventing energy accumulation that could harm human collaborators.
3Object-affected harmful factors
If the robotic system uses velocity-based control in a virtual flow field, then safety is improved by avoiding potential energy storage, but control complexity increases due to flow field modeling
Solution Approach 1:
The patent creates a virtual copy of a viscous flow field in the configuration space of the robot. This virtual flow field model serves as a simplified representation that captures the essential guidance behavior without requiring complex physical implementations. By copying the mathematical properties of viscous flow rather than implementing physical viscous elements, the system achieves safety with manageable computational complexity.
Solution Approach 2:
The patent replaces complex physical safety mechanisms with a computational model of viscous flow. Instead of using physical dampers, springs, or mechanical safety devices, the system uses software-based velocity-proportional control that mathematically simulates viscous drag, achieving safety through computation rather than complex mechanical systems.
Data Source
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AI summary
An exemplary robotic control system for controlling the controllable joints by the controller. The control method provides for determining a configuration space for the robotic system and determining a reference movement path within the configuration space. The control method then provides for assigning a plurality of streamlines in the configuration space to yield a flow field based on the reference movement path. The control method then provides for measuring actual velocity vectors of the robotic system in the configuration space. The control method then provides for determining an error velocity vector based on a difference between the actual velocity vector and the desired velocity vector given by the flow field corresponding to the current robot configuration. The control method then provides for applying a total control vector at the plurality of controllable joints, by the controller, based on the error velocity vector