Active Drive Medical Apparatus Force Feedback via Driving Torque
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Solution Overview
Problem
In medical apparatus such as endoscopes and treatment instruments, it is challenging to detect external forces acting on thin insertion sections due to the difficulty in mounting force sensors at the distal end, leading to inadequate feedback for operators during operations within body cavities.
Innovation Solution
An active drive type medical apparatus with a rotatable joint near the distal end, featuring an active mechanism driven by an electric motor, a position/attitude detecting section, an instruction input section, and a force calculating section that calculates the net external force by subtracting the estimated driving force from the actual driving force, allowing for feedback to the operator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a force sensor is mounted at the distal end of a thin insertion section, then external force detection precision is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent uses the driving force transmission mechanism as an intermediary to indirectly measure external forces. Instead of placing sensors at the distal end, the system measures the driving force at the proximal end through the bending wire or drive shaft, which transmits both control forces and external reaction forces. This intermediary approach allows force detection without direct sensor placement at the difficult-to-access distal end.
Solution Approach 2:
The patent replaces mechanical force sensors with a force calculation based on driving force measurements. By measuring the electrical current or torque of the driving motor and calculating the corresponding driving force, the system substitutes direct mechanical sensing with an electrical-mechanical conversion approach, simplifying the overall device structure.
2Measurement precision
If a force sensor is mounted at the distal end of a thin treatment instrument, then external force detection precision is improved, but ease of manufacture deteriorates
Solution Approach 1:
The driving mechanism serves as an intermediary element that transmits forces from the distal end back to the proximal end where measurements are taken. This allows the system to detect external forces acting on the treatment instrument without requiring direct sensor installation at the distal end, thereby simplifying manufacturing processes.
Solution Approach 2:
The patent extracts the force sensing function from the distal end structure and relocates it to the proximal end driving mechanism. By separating the sensing function from the treatment instrument itself and placing it in the driving system, the treatment instrument can be manufactured independently without integrating complex sensing components.
3Device complexity
If tension sensor is provided on operator's side to measure driving force, then device complexity is reduced, but measurement precision of external force deteriorates
Solution Approach 1:
The patent implements a feedback mechanism that continuously measures the driving force and uses it to calculate external forces acting on the insertion section or treatment instrument. By feeding back the driving force information and processing it through control algorithms, the system achieves accurate external force measurement despite using a simpler proximal-end sensing approach.
Solution Approach 2:
The patent transforms the measurement parameter from direct external force at the distal end to driving force at the proximal end. By changing the measurement location and parameter, the system maintains measurement capability while simplifying device structure. The control section processes these parameter changes to derive accurate external force information.
Data Source
AI summary
An active drive type medical apparatus includes: an active mechanism having a rotatable joint provided near the distal end of a long member; an active mechanism driving section; a position/attitude detecting section configured to detect a position/attitude of the active mechanism; an instruction input section for performing instruction input of the position/attitude of the active mechanism; and a force calculating section configured to calculate, on the basis of the instruction input of the position/attitude, a force corresponding to a net external force acting on the active mechanism, by subtracting an estimated driving force estimated in the case where the active mechanism in a no-load state is driven, from a driving force required in the case where the active mechanism is actually driven by the active mechanism driving section from the position/attitude before the instruction input to the instructed and inputted position/attitude.