Robotic Surgical Instrument Tip Vibration Control
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Solution Overview
Problem
Robotic surgical systems experience vibrations at the tip of surgical instruments, which cause control problems for surgeons during minimally invasive procedures, and existing solutions like low pass filters introduce delays that destabilize the control system, limiting the ability to filter out vibrations and provide haptic force feedback.
Innovation Solution
A robotic arm assembly joint controller that filters the output of the master manipulator to reduce vibrations and compensates for the delay in the feedback path using an inverse filter, ensuring stability and effective force feedback to the surgeon.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a low pass filter is employed to filter out master manipulator motion commands that cause vibrations, then vibrations at the surgical instrument tip are reduced, but delay is inserted into the teleoperation system which drives the control system unstable
Solution Approach 1:
The patent applies inverse filtering to the feedback path, which is the opposite approach of conventional filtering. Instead of filtering the master manipulator commands forward, an inverse filter is applied to the feedback signals from the surgical instrument, effectively canceling out the delay introduced by the low pass filter and stabilizing the control system while maintaining vibration reduction
Solution Approach 2:
The patent introduces an inverse filter as an intermediary element in the feedback path. This inverse filter acts as a mediator that compensates for the phase lag and delay introduced by the low pass filter, allowing the system to maintain both vibration reduction and control stability simultaneously
2Ease of operation
If a low pass filter is used to reduce vibrations, then fine surgical manipulations become easier to perform, but the ability to provide haptic force feedback to the surgeon is limited
Solution Approach 1:
The patent segments the control system into separate forward and feedback paths with different filtering characteristics. The low pass filter is applied to the forward master manipulator commands to reduce vibrations and improve ease of operation, while the inverse filter is applied to the feedback path to preserve haptic force feedback information, allowing both functions to coexist
Solution Approach 2:
The patent applies different filtering qualities to different parts of the control system. The forward path receives strong low pass filtering for vibration reduction, while the feedback path receives inverse filtering to maintain high-frequency information for haptic feedback, creating local quality differences that satisfy both requirements
Data Source
AI summary
A robotic surgical system has a robot arm holding an instrument for performing a surgical procedure, and a control system for controlling movement of the arm and its instrument according to user manipulation of a master manipulator. The control system includes a filter in its forward path to attenuate master input commands that may cause instrument tip vibrations, and an inverse filter in a feedback path to the master manipulator configured so as to compensate for delay introduced by the forward path filter. To enhance control, master command and slave joint observers are also inserted in the control system to estimate slave joint position, velocity and acceleration commands using received slave joint position commands and torque feedbacks, and estimate actual slave joint positions, velocities and accelerations using sensed slave joint positions and commanded slave joint motor torques.