Continuum Robot Wire Compensation for Accurate Bending Control
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Solution Overview
Problem
Current continuum robot control methods using wires for driving force transmission in minimally invasive medical procedures, such as endoscopes, result in errors between target posture and actual curvature due to wire deformation, increasing the risk of contact with body cavity walls.
Innovation Solution
A continuum robot control device that computes a compensation amount for the driving amount of wires based on a target bending angle and wire displacement, reducing the error between target and actual curvature, and sets a driving control amount to minimize contact risk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If long and thin wires are used as driving transmission mechanism to reach narrow spaces in deep parts of the body, then the ability to reach narrow spaces is improved, but the wires deform greatly under tensile force resulting in error between target posture and actual curvature
Solution Approach 1:
The system performs preliminary calculation of wire displacement based on the target bending angle before actuation. The control device computes the relationship between target curvature and wire displacement in advance, allowing the system to pre-determine the correct wire driving amount that compensates for expected deformation, thereby achieving accurate curvature control despite using long, thin wires
Solution Approach 2:
The control device establishes a feedback mechanism where the target bending angle is used to calculate the corresponding wire displacement, which then determines the actual driving amount. This closed-loop approach continuously adjusts the wire actuation based on the desired curvature, compensating for deformation effects and maintaining precision
2Device complexity
If kinematics-based control is used to compute wire driving amount, then the control method is simple, but error occurs between target posture and actual curvature due to wire deformation
Solution Approach 1:
The system transforms the control parameter from direct wire driving amount (based on rigid wire assumption) to wire displacement (based on elastic deformation model). By changing the fundamental parameter used for control calculation, the system maintains computational simplicity while achieving accurate curvature control that accounts for wire flexibility and deformation
3Device complexity
If wires are made rigid in longitudinal direction assumption, then control calculation is simplified, but the risk of contact between bendable portion and body cavity wall increases due to deformation error
Solution Approach 1:
The system converts the harmful effect of wire deformation into a beneficial control mechanism. Instead of ignoring deformation as in the rigid wire assumption, the system explicitly models and calculates the displacement caused by elastic deformation, using this information to adjust the driving amount and achieve accurate curvature control, thereby eliminating the contact risk while maintaining computational feasibility
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces the angle error and risk of contact between the continuum robot and body cavity walls, enhancing the precision and safety of minimally invasive procedures by compensating for wire deformation.
Implementation Method 1
the wires serving as the driving transmission mechanism preferably are long and thin. However, such wires deform greatly under tensile force occurring at the time of pushing and pulling.
Implementation Method 2
such wires deform greatly under tensile force occurring at the time of pushing and pulling
Data Source
AI summary
A continuum robot control device, configured to control operations of a continuum robot having a bendable portion that is bent by driving at least part of a plurality of wires, includes a kinematics computing unit that computes a driving amount lk1b of the at least part of the plurality of wires, based on a target bending angle that is a target value for a bending angle of the bendable portion, a compensation amount computing unit that computes a compensation amount for compensation of the driving amount lk1b, based on the target bending angle, and a displacement of one of the plurality of wires at the target bending angle, and an adding unit and position control unit that set a driving control amount of performing driving control of the at least part of the plurality of wires, based on the driving amount and the compensation amount obtained by computation.