Master-Slave Robot Control via Force Projection and Singularity Mapping
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Solution Overview
Problem
Conventional bilateral control systems face challenges such as the need for working force sensors on slave robots, limited backdrivability of master robots, instability due to external forces, and singular configuration problems, which affect the accuracy and stability of master-slave systems.
Innovation Solution
The force-projecting bilateral control system eliminates the need for working force sensors on slave robots by using an operating force sensor on the master robot, allowing the master to drive the slave through measured force, and employs a mapping to avoid singular configurations for both master and slave robots, ensuring stable operation across the entire range of movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If force-reflecting bilateral control is used to improve transparency, then the operator can feel the slave working force, but a working force sensor is required on the slave robot which increases device complexity
Solution Approach 1:
The patent introduces an operating force sensor on the master robot as an intermediary device to measure the master operating force, which then serves as the basis for controlling the slave robot. This eliminates the need for a working force sensor on the slave robot while maintaining the force feedback function, thereby reducing device complexity while preserving transparency.
2Manufacturing precision
If position control is applied to the slave robot to improve positioning accuracy, then the slave can precisely reach target positions, but singular configuration problems occur that affect system stability
Solution Approach 1:
The patent transitions from static position control to dynamic force control for the slave robot. By controlling the slave in terms of driving force rather than position, the system avoids singular configuration problems that plague position control, while maintaining operational effectiveness through force-based actuation.
3Ease of operation
If the master robot is designed with high backdrivability to improve operability, then the operator can easily manipulate the master, but the master dynamics heavily influence the master operating force reducing control accuracy
Solution Approach 1:
The patent replaces the mechanical backdrivability requirement with an electronic force measurement and control system. By using an operating force sensor to measure the master operating force and electronically controlling the slave based on this force measurement, the system eliminates the need for high mechanical backdrivability while maintaining ease of operation and improving force measurement accuracy.
4Adaptability or versatility
If the slave robot operates mechanically independently from the master to improve flexibility, then the slave can perform diverse tasks, but the system becomes unstable when external forces are applied to the slave
Solution Approach 1:
The patent implements a feedback control mechanism where the measured master operating force is continuously used to adjust the slave robot's driving force. This closed-loop feedback system maintains stability even when the slave operates mechanically independently and encounters external forces, as the control system actively compensates for disturbances based on the operator's intended actions.
Data Source
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AI summary
A master-slave system (1) according to the present invention includes at least one master displacement sensor (Pm1 to Pm3) for measuring a master displacement for a master robot, at least one slave displacement sensor (Ps1 to Ps3) for measuring a slave displacement for a slave robot, a master target displacement calculating device (2) for mapping the slave displacement and thereby obtaining a master target displacement which is a target value for the master displacement corresponding to the slave displacement, and a master actuator (Am1 to Am3) for generating a master driving force to position-control the master robot on the basis of the master target displacement and the master displacement. The mapping is predefined such that a set of master target displacements excludes a singular configuration for the master robot. The master-slave system (1) renders it possible to solve a singular configuration problem for both the master robot and the slave robot.