Robotic Manipulator Tool-Tip Estimation for Vibration Control
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Solution Overview
Problem
Robotic manipulators experience undesirable vibrations due to flexibility and low mechanical resonance, leading to poor control and deviation from commanded trajectories, especially during minimally invasive medical procedures.
Innovation Solution
A system that utilizes both motor side and load side sensor data to generate accurate tool tip estimates, controlling the joint based on the difference between these estimates to mitigate vibrations and improve control precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the robotic manipulator uses flexible links and joints to achieve compliance, then adaptability is improved, but stability deteriorates due to under-damped vibrations
Solution Approach 1:
The system employs feedback control using sensor data from both the motor side and load side to generate accurate tool tip estimates. The controller compares the estimated tool tip position with the commanded position and adjusts joint commands to reduce vibrations, thereby maintaining stability while preserving compliance.
Solution Approach 2:
The patent replaces pure mechanical rigid structures with a hybrid system that combines flexible mechanical components with advanced control algorithms. The control system substitutes for mechanical rigidity by actively compensating for vibrations through sensor feedback and computational estimation, allowing compliance without sacrificing stability.
2Strength
If the robotic manipulator has large link masses and inertias, then strength is improved, but stability deteriorates due to low mechanical resonance
Solution Approach 1:
The control system uses feedback from motor side and load side sensors to detect and compensate for vibrations caused by large link masses. The feedback loop continuously adjusts joint commands to counteract the low mechanical resonance effects, maintaining stability despite the heavy construction.
Solution Approach 2:
The system dynamically adjusts control parameters based on the actual state of the manipulator. By changing control gains and compensation parameters in real-time based on sensor feedback, the system optimizes the balance between strength and vibration resistance, allowing heavy links to provide strength without excessive resonance.
3Manufacturing precision
If the robotic manipulator operates with high precision control, then manufacturing precision is improved, but reliability deteriorates due to vibrations causing deviation from commanded trajectories
Solution Approach 1:
The system uses dual-side sensor feedback to create an accurate model of the tool tip position and compares it with the commanded trajectory. The feedback controller continuously corrects deviations caused by vibrations, ensuring both high precision and reliable trajectory following.
Solution Approach 2:
The patent introduces an intermediary computational model that estimates the tool tip position based on sensor data from both motor and load sides. This intermediary estimation acts as a mediator between the commanded trajectory and the actual manipulator state, smoothing out vibration effects and improving both precision and reliability.
Data Source
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AI summary
A system comprises a robotic manipulator for control of motion of a medical tool. The robotic manipulator including a joint and a link connected to the joint. The link is configured to connect to the medical tool. A processing unit of the system is configured to receive first data from an encoder of the joint. A first tool tip estimate of a first parameter of a tool tip coupled at a distal end of the medical tool is generated using the first data. The first parameter of the tool tip is a position or a velocity of the tool tip. Second data is received from a sensor system located at a sensor portion of the link or the medical tool. The joint is controlled based on a first difference between the first tool tip estimate and a second tool tip estimate generated using the first and second data.