Tendon-Driven Endoscope Controller With Friction Compensation
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Solution Overview
Problem
Current endoscopic surgical instruments lack dexterity and sensitivity, particularly in delicate surgeries like neurosurgery, due to the rigidity of their mechanical structure, which limits precise manipulation and control, especially when interacting with critical brain tissues and nerves.
Innovation Solution
A tendon-driven continuum robot with a forward-kinematic-mapping unit that accounts for friction forces to accurately estimate and control angular displacement, allowing for flexible and precise bending of the endoscope, enabling better maneuverability and reduced risk of damaging surrounding tissues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a rigid or flexible sheath is used in conventional endoscopic instruments, then the structural strength and simplicity are maintained, but the dexterity and sensitivity for precise manipulation are reduced
Solution Approach 1:
The sheath is divided into multiple rigid sections that can articulate relative to each other, allowing the endoscope to bend and maneuver while maintaining structural integrity. Each section can be independently controlled to achieve precise positioning and dexterity in delicate surgical operations.
Solution Approach 2:
The endoscopic instrument transitions from a static rigid or flexible sheath to a dynamic articulated structure with multiple movable sections. The articulation joints enable real-time adjustment of the sheath configuration, providing enhanced dexterity and sensitivity for precise manipulation of surgical tools.
2Strength
If the sheath is made rigid to maintain structural strength, then the mechanical strength is improved, but the ability to bend precisely without exerting excessive force is reduced
Solution Approach 1:
The sheath is segmented into multiple rigid sections connected by articulation joints, allowing each section to maintain its structural strength while the overall structure can bend precisely. The segmentation enables force distribution across multiple joints, preventing excessive force concentration at any single point.
Solution Approach 2:
The endoscope achieves bending capability by articulation in multiple dimensions through the articulation joints between sections. This multi-dimensional articulation allows precise control of the sheath configuration in complex spatial arrangements without compromising the structural strength of individual rigid sections.
3Measurement precision
If friction between tendon and body is ignored in control calculations, then the computational simplicity is maintained, but the measurement precision of angular displacement is reduced
Solution Approach 1:
The control system incorporates friction compensation based on measured or estimated friction forces between the tendon and body. This feedback mechanism adjusts the control calculations to account for friction effects, improving the accuracy of angular displacement estimation while maintaining manageable computational complexity through iterative or approximate methods.
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 enhances the dexterity and sensitivity of endoscopic instruments by accurately controlling the bending of the endoscope, improving the precision and safety of surgical procedures, particularly in neurosurgery, by incorporating friction compensation in the kinematic mapping for precise tension and curvature management.
Implementation Method 1
the relationship is based on information of friction between the tendon and the body
Data Source
Figure 1(a)~1(c)
Figure 2(a)~2(b)
Figure 3(a)~3(b)
AI summary
An apparatus including a tendon-driven device such as an endoscope comprising a bendable body, a tendon attached to and extending a length of said body, and an actuator that will actuate said tendon based on a control signal from a controller. The controller is configured to send said control signal to said actuator and comprises a forward-kinematic-mapping unit that estimates an angular displacement, wherein the kinematic-mapping unit is configured for: providing a tension value of the tendon to obtain a desired angular displacement wherein the tension has a nonlinear relationship with the desired angular displacement based on information of friction where the tension is greater that would be calculated without including the effect of friction. The friction coefficient may be determined as it changes over time.