Master-Slave Manipulator Pneumatic Force Feedback Control

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Solution Overview

Problem

Current multi-DOF forceps systems for endoscopic surgery lack sufficient degrees of freedom, operability, and effective force feedback due to high reduction ratios in electric actuators and difficulties in integrating force sensors, leading to bulky and inefficient systems.

Innovation Solution

A manipulation system with a master manipulator operating under electrically-driven speed control and a slave manipulator under pneumatically-driven force control, utilizing pneumatic actuators to provide force feedback and estimate external forces, eliminating the need for force sensors and optimizing degrees of freedom through delta and gimbal mechanisms.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If electric actuators with high reduction ratio are used to drive the master and slave portions, then controllability is improved, but force feedback capability deteriorates due to inability to feed minute force back to the operator

Engineering Contradiction:

ImprovecontrollabilityVSAvoidforce feedback capability

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent replaces electric actuators with pneumatic actuators (pneumatic cylinders) to drive the slave manipulator. Pneumatic actuators can directly transmit force without high reduction gears, enabling minute force feedback to be transmitted to the operator while maintaining controllability through pressure control.

Inventive Principle:

Principle #29Pneumatics and hydraulics

Solution Approach 2:

The patent substitutes the electric actuator mechanism with a pneumatic actuator mechanism. This replacement eliminates the need for high reduction ratio gears in the slave manipulator, allowing direct force transmission for bidirectional control and force feedback.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If force sensors are attached to the forceps to provide force feedback, then force feedback capability is improved, but device complexity and difficulty of manufacture increase due to sterilization and calibration requirements

Engineering Contradiction:

Improveforce feedback capabilityVSAvoidease of attaching force sensor

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The slave manipulator uses its own pneumatic actuator system to provide force feedback. The pneumatic cylinders inherently possess force sensing capability through pressure measurement, eliminating the need for separate force sensors. This self-service approach simplifies the system while maintaining force feedback functionality.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent uses pneumatic pressure as an intermediary to sense and transmit force information. Instead of attaching force sensors directly to the forceps, the system uses the pneumatic pressure in the actuator cylinders as a mediator to infer external forces, avoiding sterilization and calibration issues.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Strength

If pneumatic actuators are used to drive the slave manipulator, then passive softness and high mass-to-output ratio are improved, but controllability deteriorates due to nonlinear characteristics

Engineering Contradiction:

Improvepassive softness and mass-to-output ratioVSAvoidcontrollability

Core Design Contradiction:

StrengthVSEase of operation

Solution Approach 1:

The patent implements bidirectional control with force feedback using pneumatic actuators. By measuring the pressure in the pneumatic cylinders and feeding this force information back to the master manipulator, the system compensates for the nonlinear characteristics of pneumatic actuators, maintaining controllability while preserving their inherent advantages of passive softness and high mass-to-output ratio.

Inventive Principle:

Principle #23Feedback

4Device complexity

If the slave manipulator is designed with only three degrees of freedom, then device complexity is reduced, but operability deteriorates as it cannot reproduce human hand motion

Engineering Contradiction:

Improvedegrees of freedomVSAvoidoperability

Core Design Contradiction:

Device complexityVSEase of operation

Solution Approach 1:

The patent designs the slave manipulator with seven degrees of freedom to match the human hand's mobility. This dynamic configuration allows the slave manipulator to reproduce complex human hand motions including wrist rotation and finger movements, significantly improving operability while maintaining manageable system complexity through modular design.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS8897916B2Maneuvering system having inner force sense presenting function

Publication Date: 2014.11.25 RIVERFIELD INC

AI summary

A compact, lightweight manipulation system that excels in operability and has a force feedback capability is provided. When automatic operation of a slave manipulator 105 that follows manual operation of a master manipulator 101 is bilaterally controlled by means of communication, the force acting on the slave manipulator is fed back to the master manipulator by operating the master manipulator primarily under electrically-driven speed control and the slave manipulator primarily under pneumatically-driven force control. Therefore, in the master manipulator, it is not necessary to compensate for the dynamics and the self-weight of the master manipulator in the motion range of a user, allowing highly accurate, broadband positional control, which is specific to an electrically-driven system, and in the slave manipulator, nonlinearity characteristics specific to a pneumatically-driven system presents passive softness, provides a high mass-to-output ratio, and produces a large force.