Manipulator Joint Displacement Detection via Magnetic Sensing
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Solution Overview
Problem
Current medical manipulators used in laparoscopic surgery face challenges in accurately detecting joint displacement within the limited space of a 10 mm diameter, especially when using thin power transmission wires, as existing methods like potentiometers or encoders near the motor are not precise and can be affected by heat and pressure during sterilization.
Innovation Solution
A manipulator joint displacement detection mechanism that includes a sensing wire connected to a power transmission wire, guided by a tubular sensing guide tube, and detected by a noncontact magnetic sensor, allowing precise displacement measurement without increasing the manipulator's diameter, using a pneumatic actuator system to transmit forces to the joint, and fixing the guide and sensor holders to maintain accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a potentiometer or encoder is placed close to the driving source to detect joint displacement, then the detection method is simple, but the measurement precision is insufficient and the sensor is affected by heat and pressure during sterilization
Solution Approach 1:
The patent replaces the mechanical sensing system (potentiometer or encoder) with a magnetic sensing system. A magnetic sensor detects the position of a magnetic member attached to the power transmission wire, eliminating mechanical contact and improving measurement precision while resisting heat and pressure during sterilization.
Solution Approach 2:
The patent introduces a magnetic field as an intermediary between the power transmission wire and the sensor. The magnetic member on the wire interacts with the magnetic sensor through the magnetic field, allowing non-contact detection and isolating the sensor from harsh sterilization conditions.
2Measurement precision
If a magnetic sensor and guide tube system is implemented to improve detection precision, then measurement precision improves, but the device complexity increases
Solution Approach 1:
The guide tube serves multiple functions: it guides the power transmission wire, positions the magnetic member, and protects the sensing system. This multi-functionality reduces the need for separate components, managing device complexity while maintaining measurement precision.
Solution Approach 2:
The magnetic member is attached to the power transmission wire, which is inserted into the guide tube. This nested arrangement integrates multiple components in a compact configuration, improving detection precision without proportionally increasing device complexity.
3Length of moving object
If the manipulator diameter is kept at 10 mm or less to fit through the trocar, then the manipulator can be inserted into the patient's abdomen, but the space for power transmission and sensing components is limited
Solution Approach 1:
The patent uses a thin-walled guide tube that provides structural guidance and protection while occupying minimal space. This allows the manipulator to maintain a diameter of 10 mm or less while still accommodating the power transmission wire and magnetic sensing components.
Solution Approach 2:
The patent arranges components along the longitudinal axis of the manipulator, utilizing the length dimension to accommodate components that would otherwise require radial space. This allows sufficient component placement while maintaining a compact 10 mm diameter.
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
This configuration enables precise detection of joint displacement with reduced friction and heat resistance, improving accuracy over conventional methods and allowing for more precise operation of the manipulator's clutching unit without increasing the diameter of the medical manipulator.
Implementation Method 1
a noncontact magnetic sensor, allowing precise displacement measurement
Data Source
AI summary
A manipulator joint displacement detection mechanism includes a manipulator which has a actuating unit and a joint. A first transmission member is connected to the joint, and provided movably to displace the joint. A second transmission member moves corresponding to movement of the first transmission member. A guide guides movement of the second transmission member. A guide fixing part fixes one end and the other end of the guide. A sensor detects a moving distance of the second transmission member in the proximal end portion of the manipulator.