Robotic Manipulator Link Sensing 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 inferior system performance and difficulty in maintaining precise control, especially when moving around a remote center of motion, which can result in unwanted forces on the patient's body.

Innovation Solution

A robotic system with a processing unit that receives data from sensor systems on the links and joints to generate state estimates and control the manipulator, using a kinematic model to mitigate vibrations by improving joint and section state estimation and control, thereby reducing vibration amplitudes and settling times.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the robotic manipulator uses flexible links and large masses for structural compliance, then the manipulator can adapt to varying procedural requirements, but vibrations are excited with long settling times causing inferior control performance

Engineering Contradiction:

Improvestructural complianceVSAvoidcontrol performance

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The system employs sensor systems on links and joints to provide real-time state information to a processing unit. The processing unit generates state estimates and uses feedback control to actively suppress vibrations caused by flexible links and large masses, maintaining control performance while preserving structural compliance for adaptability.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system dynamically adjusts control parameters including damping coefficients and stiffness values based on real-time state estimates. By changing these parameters adaptively, the system can compensate for vibrations induced by flexible links and large masses, resolving the contradiction between compliance and control reliability.

Inventive Principle:

Principle #35Parameter changes

2Ease of operation

If the robotic manipulator moves around a remote center of motion, then minimally invasive procedures can be performed through natural orifices, but vibrations cause the remote center to move beyond tolerance imparting unwanted forces on the patient's body

Engineering Contradiction:

Improveminimally invasive accessVSAvoidunwanted forces on body wall

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

Sensor systems monitor the position and state of the manipulator around the remote center of motion. The processing unit uses this feedback to generate accurate state estimates and apply compensatory control actions that keep the remote center within defined tolerances, preventing unwanted forces on the patient's body wall while maintaining minimally invasive access.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system replaces purely mechanical positioning with a hybrid control approach using sensor feedback and computational state estimation. This substitution allows the remote center to be maintained within tolerances through active control rather than passive mechanical constraints, eliminating harmful forces while preserving ease of operation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Device complexity

If the robotic manipulator uses traditional control methods, then the system structure is simpler, but vibrations make it difficult to achieve or follow commanded trajectories

Engineering Contradiction:

Improvecontrol system structureVSAvoidtrajectory accuracy

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The system uses sensor feedback from links and joints to continuously monitor actual positions and generate state estimates. This feedback loop enables the processing unit to compute and apply corrective control actions that compensate for vibrations, achieving accurate trajectory following without requiring overly complex mechanical structures.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The processing unit acts as an intermediary between simple sensor measurements and control actuation. It generates state estimates that bridge the gap between raw sensor data and control commands, enabling accurate trajectory control through computational processing rather than complex hardware.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS11173597B2Systems and methods for controlling a robotic manipulator or associated tool

Publication Date: 2021.11.16 INTUITIVE SURGICAL OPERATIONS INC

AI summary

A system includes a robotic manipulator including a serial chain comprising a first joint, a first link, and a second link. The second link is between the first joint and the first link in the serial chain. 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 a kinematic model of the robotic manipulator, and control the first joint based on the first joint state estimate.