Robotic Surgery Input Shaping for Variable-Frequency Vibration Control
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Solution Overview
Problem
Robotic surgical systems face challenges in accurately determining the position and pose of the setup arm within the surgical environment, which affects the control of surgical instruments and can lead to vibrations due to varying resonant frequencies, requiring an input shaper algorithm that minimizes latency and adapts to changing resonant frequencies.
Innovation Solution
The implementation of a velocity-based input shaper algorithm that calculates the resonant frequency of each joint based on a frequency map, adjusts the time delay and weighting of the overshoot in real-time, and applies a phase look-ahead algorithm to smooth joint movements, ensuring minimal latency and effective vibration suppression across varying resonant frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional position-based control is used, then the system is simple to implement, but vibrations occur due to varying resonant frequencies
Solution Approach 1:
The patent changes the control parameter from position to velocity. The velocity-based input shaper algorithm processes desired velocity commands rather than position commands, allowing the system to suppress vibrations by shaping the velocity profile to avoid exciting resonant frequencies while maintaining straightforward implementation
2Object-generated harmful factors
If resonant frequency compensation is implemented, then vibration suppression improves, but system complexity increases
Solution Approach 1:
The system uses the robot's own motion state (current velocity and position) and pre-characterized resonant frequency data to automatically adjust the control signal. The velocity-based input shaper algorithm retrieves resonant frequencies from a frequency map and computes compensation signals without requiring external sensors or complex real-time frequency identification, making the system self-regulating
3Measurement precision
If real-time frequency adaptation is used, then accuracy is improved, but latency increases
Solution Approach 1:
The system performs frequency characterization in advance and stores resonant frequencies in a frequency map associated with different robot configurations. During operation, the velocity-based input shaper algorithm simply looks up the appropriate frequencies from this pre-computed map based on the current configuration, avoiding real-time frequency measurement and computation while maintaining accuracy
4Object-generated harmful factors
If velocity-based control is implemented, then vibration suppression is enhanced, but computational requirements increase
Solution Approach 1:
The system uses a velocity-based input shaper algorithm that copies and adapts classic input shaping techniques from the position domain to the velocity domain. By processing velocity commands through a modified shaping algorithm that uses the same frequency map structure, the system achieves vibration suppression with computational efficiency similar to traditional methods
Data Source
AI summary
Input shapers for control inputs to the robotic surgical system and their method of controlling a linkage of a robot with a controller includes receiving a desired joint angle of a joint of the robot; and transmitting a first control signal to a motor to actuate the joint in response to a desired joint velocity, the desired joint velocity being a function of the desired joint angle and a current joint angle of the joint.