Surgical Robot Bilateral Control for Stable Force Feedback
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Solution Overview
Problem
Existing master-slave surgical robots face limitations in increasing the gain of proportional control for improved force feedback sensitivity due to issues like slack wires, gaps in transmission structures, and control delays.
Innovation Solution
The surgical robot system includes a master and slave configuration with controllers that calculate control values based on surgical tool states and target states, allowing for asymmetrical bilateral control combining proportional and integral control to enhance force feedback sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the gain of proportional control is increased to improve force feedback sensitivity, then force feedback sensitivity is improved, but control stability deteriorates due to slack wires, gaps in transmission structures, and control delays
Solution Approach 1:
The patent implements asymmetrical bilateral control where the master controller receives feedback not only from force sensors detecting contact between the surgical tool and tissue, but also from the slave control value calculated by the slave controller. This dual feedback mechanism allows the master controller to adjust the reaction force based on both actual contact force and slave position error, enabling stable control even with high proportional gain by compensating for transmission delays and mechanical slack through the additional feedback channel.
Solution Approach 2:
The patent changes the control parameter structure by introducing asymmetrical bilateral control that combines proportional control and integral control differently in the master and slave controllers. The master controller uses a different control gain structure than the slave controller, allowing independent optimization of force feedback sensitivity and control stability. This parameter differentiation enables the system to achieve high sensitivity without the instability that would normally result from uniformly high gains throughout the system.
2Measurement precision
If asymmetrical bilateral control combining proportional and integral control is used to improve force feedback sensitivity, then force feedback sensitivity and control accuracy are improved, but device complexity increases
Solution Approach 1:
The patent merges the control functions by having the master controller calculate the master control value based on both force sensor output and the slave control value from the slave controller. This integration of multiple control signals into a unified control architecture achieves the benefits of asymmetrical bilateral control while avoiding the complexity of completely separate control systems. The merging of feedback channels and control calculations in the master controller simplifies the overall structure compared to fully independent master and slave control systems.
Data Source
AI summary
A surgical robot includes a master, a master controller, a slave, and a slave controller. The slave controller calculates a slave control value based on a target state and a surgical tool state, the slave control value being for controlling a surgical tool, the target state being a state of the surgical tool based on an operation received by the master, the slave controller controlling the slave based on the slave control value. The master controller calculates a master control value based on the surgical tool state, the target state, and the slave control value obtained from the slave controller, the master control value being for controlling the reaction force, the master controller controlling the master based on the master control value.