Robotic Manipulator Joint Weighting for Resonance Vibration Control
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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 inferior system performance and difficulty in maintaining precise control, especially when operating around a remote center of motion.
Innovation Solution
A system with a processing unit that receives data from link sensors to generate joint state estimates and applies weights to these estimates to control the joints, reducing vibrations and improving control precision by mitigating the effects of mechanical resonance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If robotic manipulator flexibility and mass are increased to improve payload capacity and reach, then the manipulator can perform more complex medical procedures, but vibrations are exacerbated due to under-damped mechanical resonances
Solution Approach 1:
The patent implements a feedback control system that uses sensors to detect vibrations at the tool tip and commands counteracting motions through the robotic manipulator. The control system continuously monitors tool tip position and velocity, calculates desired counteracting motions, and applies them through the manipulator joints to cancel out harmful vibrations while maintaining payload capacity.
Solution Approach 2:
The patent dynamically changes control parameters including damping coefficients and stiffness values based on the current operational state. The control system adjusts these parameters in real-time to optimize vibration suppression across different frequency ranges and operational conditions, allowing the manipulator to maintain both payload capacity and vibration control.
2Adaptability or versatility
If robotic manipulator flexibility is increased to improve dexterity in minimally invasive procedures, then the manipulator can access difficult-to-reach tissue locations, but settling time increases due to under-damped vibrations
Solution Approach 1:
The patent applies preliminary counteracting motions before the manipulator completes its intended movement. The control system predicts upcoming vibrations based on commanded motions and applies compensating actions in advance, allowing the manipulator to reach difficult locations quickly while minimizing settling time through pre-applied damping effects.
Solution Approach 2:
The patent uses periodic control actions that apply vibrations at specific frequencies to counteract harmful resonances. By applying controlled periodic motions through the manipulator joints, the system can cancel out under-damped vibrations and reduce settling time while maintaining dexterity for accessing difficult tissue locations.
3Object-generated harmful factors
If traditional vibration suppression methods are applied to robotic manipulators, then vibration amplitudes may be reduced, but the complexity of the control system increases significantly
Solution Approach 1:
The patent implements a self-service control approach where the robotic manipulator uses its own actuators and structure to generate counteracting motions rather than requiring separate vibration suppression hardware. The control system leverages the manipulator's existing components to cancel vibrations, reducing overall system complexity while effectively reducing vibration amplitudes.
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.