Master-Slave Teleoperation Control for Surgical Robots
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Solution Overview
Problem
In medical or surgical teleoperation, unconstrained master devices face challenges in ensuring initial alignment with slave devices during preparation for teleoperation, particularly when scaling between movements is high, leading to safety and maneuverability issues due to temporary decoupling, which affects patient and surgeon safety and comfort.
Innovation Solution
A method and system for controlling a master-slave robotic system that defines two states: a fully enslaved state and a limited teleoperation state where the slave device is decoupled from the master device in translation but follows it in orientation, allowing repositioning of the master device without translating the slave, ensuring alignment and safety during transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the slave device is completely decoupled from the master device during preparation for teleoperation, then the operator can freely reposition the master device, but the master-slave alignment cannot be ensured
Solution Approach 1:
The patent segments the degrees of freedom into two categories: orientation degrees of freedom (which remain coupled between master and slave devices) and position degrees of freedom (which are decoupled). This allows the operator to freely reposition the master device while the slave device maintains its orientation alignment, resolving the contradiction between repositioning freedom and alignment assurance.
2Reliability
If the master device is mechanically constrained to the console, then the master-slave orientation alignment can be maintained, but the operator cannot freely reposition the master device
Solution Approach 1:
The patent implements a dynamic control mode that allows the system to switch between mechanically constrained operation (for alignment) and freely repositionable operation (for flexibility). By dynamically managing the coupling of orientation degrees of freedom while maintaining decoupling of position degrees of freedom, the system achieves both alignment reliability and repositioning flexibility without requiring physical mechanical constraints.
3Manufacturing precision
If high scaling factor is used between master and slave movements, then micro-surgery precision is improved, but the operator must move hands very widely reaching the edge of workspace
Solution Approach 1:
The patent introduces a temporal dimension to the control operation by implementing a preparation phase where the slave device anticipates master device movements. During this preparation phase, the slave device pre-positions itself based on predicted master device trajectories, allowing high scaling factors to be used without requiring the operator to reach extreme positions, as the system proactively adjusts rather than reactively responding.
Data Source
AI summary
A method controls a robotic system for medical or surgical teleoperation. The robotic system includes a hand-held master device, mechanically unconstrained to the ground and moveable by an operator; and a slave device including a surgical instrument adapted to be controlled by the master device, so that movements of the slave device, or of the surgical instrument of the slave device, referred to one or more of a plurality of controllable degrees of freedom are controlled by respective movements of the master device, according to a master-slave control architecture. The method firstly includes the steps of defining a first enslaved state of the system and a second decoupled state of the system. A controller controls transitions between the first and second states. The controllable degrees of freedom include degrees of freedom of translation and of orientation. A master-slave robotic system for medical or surgical teleoperation performs the method.