End Effector Engagement Control for Precise Multi-DOF Motion

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Solution Overview

Problem

Current computer-assisted devices for teleoperated systems face challenges in effectively controlling end effectors with multiple degrees of freedom, particularly in engaging actuators and homing mechanisms, which affects the precision and efficiency of movements within surgical and industrial tasks.

Innovation Solution

A computer-assisted device with a drive unit comprising a first and second actuator, each with a corresponding engagement member, and a control unit that actuates and detects engagements to move end effectors in specific directions, servoing or continuing actuation to maintain precise control and position.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple actuators are used to control end effectors with multiple degrees of freedom, then the dexterity and range of motion are improved, but the complexity of engagement and control increases

Engineering Contradiction:
Improvedexterity of end effectorVSAvoidengagement control complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The system divides the control of multiple degrees of freedom into separate actuator modules, where each actuator is responsible for a specific degree of freedom. This segmentation allows independent control of each actuator, simplifying the overall engagement process while maintaining full dexterity of the end effector.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system performs preliminary homing actions to establish known reference positions for each actuator before operational use. By pre-positioning actuators at defined home positions and establishing reference frames, the system reduces the complexity of real-time control and simplifies engagement procedures.

Inventive Principle:
Principle #10Preliminary action

2Measurement precision

If engagement detection mechanisms are added to detect engagement of actuators with engagement members, then the precision of position control is improved, but the device complexity increases

Engineering Contradiction:
Improveengagement detection precisionVSAvoiddetection system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The system incorporates engagement detection mechanisms that provide feedback signals to the control unit when actuators engage with engagement members. This feedback enables precise determination of engagement status and facilitates accurate homing operations, improving position control precision while managing complexity through systematic feedback processing.

Inventive Principle:
Principle #23Feedback

3Manufacturing precision

If homing operations are performed to establish reference positions, then the accuracy of subsequent movements is improved, but the time required for setup increases

Engineering Contradiction:
Improvemovement accuracyVSAvoidhoming time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The system performs homing operations as a preliminary action to establish reference positions for all actuators before operational use. By completing this setup phase in advance, the system ensures high accuracy for subsequent movements while allowing the homing time to be accounted for in the overall process planning.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The homing operation is designed as a self-service process where the system automatically determines its own reference positions without requiring external intervention or complex calibration procedures. This automated self-homing reduces both the time required and the operational complexity.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP3755261B1Systems for control of end effectors
Publication Date: 2024.04.03 INTUITIVE SURGICAL OPERATIONS INC
  • EP3755261B1 patent drawingFigure 1A
  • EP3755261B1 patent drawingFigure 1B
  • EP3755261B1 patent drawingFigure 2

AI summary

A system and method of controlling an end effector includes a drive unit having a first actuator and a second actuator; a moveable platform drivably coupled to the first actuator; first and second engagement members drivably coupled to the second actuator; and a control unit. The control unit is configured to actuate the first actuator to drive the platform, detect engagement of the first engagement member with a third engagement member of an instrument, detect engagement of the second engagement member with a fourth engagement member of the instrument, and actuate the second actuator to drive the first and second engagement members. Movement of the third and engagement member causes movement of a degree of freedom of an end effector of the instrument in a first direction. Movement of the fourth engagement member causes movement of the degree of freedom in a second direction opposite the first direction.