Robotic Manipulator State Estimation for Remote Center Stability
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Solution Overview
Problem
Robotic manipulators used in medical procedures experience undesirable vibrations due to flexibility and large masses or inertias, leading to poor control and deviation from commanded trajectories, especially when moving around a remote center of motion, which can result in tissue damage and prolonged recovery times.
Innovation Solution
A robotic system with a serial chain comprising a first and second joint and a link, equipped with a processing unit that receives sensor data to generate joint state estimates and applies weights to these estimates to control the joints, reducing vibrations and improving control precision around the remote center of motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the robotic manipulator uses flexible links and large masses for structural compliance, then the manipulator can adapt to different surgical tasks, but vibrations are excited causing poor control and trajectory deviation
Solution Approach 1:
The patent applies vibration mitigation techniques that dynamically adjust system parameters (such as damping coefficients and stiffness characteristics) to suppress vibrations excited by commanded motions or external disturbances. This allows the flexible manipulator to maintain control precision while preserving its adaptability for different surgical tasks.
2Adaptability or versatility
If the robotic manipulator has large flexibility and link masses, then the manipulator can handle various surgical instruments, but the mechanical resonance has less than desired damping causing long settling times
Solution Approach 1:
The patent converts the harmful effect of flexibility-induced vibrations into a beneficial control feature by using vibration mitigation techniques that actively dampen resonant frequencies. This reduces settling time while maintaining the manipulator's ability to handle various surgical instruments.
3Manufacturing precision
If the manipulator follows commanded trajectories with high precision, then surgical accuracy is improved, but vibrations cause the remote center of motion to deviate beyond tolerance
Solution Approach 1:
The patent employs feedback control mechanisms that continuously monitor the actual position and orientation of the manipulator and the remote center of motion, comparing these measurements against commanded trajectories. Vibration mitigation algorithms use this feedback to generate corrective control actions that maintain remote center stability within tolerance while achieving accurate trajectory following.
Data Source
AI summary
A system includes a robotic manipulator including a serial chain comprising a first joint, a second joint, and a first link. The system further includes a processing unit including one or more processors. The processing unit is configured to receive first link data from a first sensor system located at the first link, generate a first joint state estimate of the first joint based on the first link data, and generate a second joint state estimate of the second joint. The processing unit is further configured to apply a first weight to the first joint state estimate to generate a first weighted joint state estimate, apply a second weight to the second joint state estimate to generate a second weighted joint state estimate, and control the first and second joints based on the first weighted joint state estimate and second weighted joint state estimate.