Surgical Manipulator Outer Sheath Tensile Force Control
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Solution Overview
Problem
Existing surgical devices with wire-driven bending sections face challenges in maintaining consistent tensile force during bending, which affects the accuracy and efficiency of end effector movement within body cavies.
Innovation Solution
A manipulator design featuring a flexible multi-lumen tube with a rigid coil tube outer sheath and an adjustable mechanism to maintain wire path length and tensile force, allowing for precise control of the end effector's movement by adjusting the position of the outer sheath relative to the motor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a wire is used to drive the end effector through a flexible insertion section, then the end effector can be actuated remotely, but the tensile force of the wire changes due to bending of the flexible insertion section
Solution Approach 1:
A constant-force spring is introduced as an intermediary component between the wire and the external environment. This spring applies a fixed initial tensile force to the wire, acting as a mediator that compensates for force variations caused by bending. The constant-force spring maintains consistent tensile force transmission despite changes in wire path geometry during bending of the flexible insertion section.
Solution Approach 2:
The patent changes the physical parameter of the wire system by applying a predetermined initial tensile force through the constant-force spring. This parameter adjustment (initial tension) compensates for the variable tensile force that would otherwise occur during bending, maintaining consistent force transmission to the end effector throughout the range of motion.
2Device complexity
If the outer sheath position is fixed relative to the motor, then the structure is simpler, but the tensile force on the wire cannot be adjusted
Solution Approach 1:
The patent transforms the static, fixed position of the outer sheath relative to the motor into a dynamic, adjustable configuration. The adjusting mechanism enables the outer sheath to be positioned at different locations along the guide tube, allowing the initial tensile force applied to the wire to be varied. This dynamic adjustability provides versatility in tensile force control while maintaining a relatively simple overall structure.
Data Source
AI summary
A manipulator including: an end effector movable about a joint; a motor configured to generate force so as to move the end effector; a wire for transmitting the force from the motor to the end effector; a guide member connected between the end effector and motor. The guide member including: a guide tube comprising at least one lumen extended in a longitudinal direction, the lumen configured to guide the wire; and an outer sheath configured to cover the guide tube in a longitudinal direction and to move relative to the motor in the longitudinal direction, the outer sheath having a rigidity higher than the guide tube. The manipulator further including an adjusting mechanism configured to adjust a position of the proximal end section of the outer sheath relative to the motor in the longitudinal direction of the guide tube so as to adjust a tensile-force generated on the wire.