Surgical Arm Force Control With Inclination-Based Gravity Compensation
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Solution Overview
Problem
Surgical arm devices in force control mode face challenges in maintaining accurate gravity compensation when attached to inclined operating tables, leading to unbalanced movements and potential accidents during medical procedures.
Innovation Solution
A control system that acquires inclination information, sets computational conditions for gravity compensation, and calculates torque command values using generalized inverse dynamics to ensure accurate force control, correcting for disturbances and maintaining alignment with a logical response model.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If force control mode is used to enable flexible response to external force, then the surgical arm device can perform tasks through physical interactions with the external world, but the system configuration becomes complicated and gravity compensation accuracy deteriorates on inclined surfaces
Solution Approach 1:
The patent changes the computational parameters by introducing inclination information (angle data) into the gravity compensation calculation. The control system dynamically adjusts the gravity compensation torque based on the detected inclination angle, transforming the control parameters to adapt to different operating conditions. This allows the force control system to maintain accuracy without requiring complex hardware modifications.
Solution Approach 2:
The patent replaces complex mechanical gravity compensation mechanisms with a computational approach. Instead of using additional mechanical counterweights or complex linkages, the system uses generalized inverse dynamics computation to calculate and apply the necessary compensation torques. This substitution of mechanical systems with computational methods reduces physical complexity while maintaining control flexibility.
2Reliability
If gravity compensation is not accurately adjusted for inclination, then the surgical arm device experiences unbalanced movements and potential accidents, but adding complex inclination detection and adjustment mechanisms increases device complexity
Solution Approach 1:
The surgical arm device performs self-compensation for inclination effects through its own control system. The inclination detection unit provides data to the control system, which then automatically adjusts the gravity compensation torques without requiring external intervention or complex additional mechanisms. The system serves itself by using its computational capabilities to detect and correct the inclination-induced imbalances.
Solution Approach 2:
The patent implements a feedback loop where the inclination detection unit continuously monitors the operating table's angle, and this information is fed back to the control system. The control system uses this feedback to dynamically adjust the gravity compensation torques, ensuring continuous accuracy. This closed-loop feedback mechanism maintains reliability without requiring overly complex hardware.
3Device complexity
If standard gravity compensation is used without inclination correction, then the system remains simple, but the surgical arm device produces harmful unbalanced movements on inclined surfaces
Solution Approach 1:
The control system applies preliminary anti-action by calculating and applying gravity compensation torques that counteract the inclination effects before they cause unbalanced movements. The generalized inverse dynamics computation proactively determines the necessary compensation based on detected inclination, preventing harmful movements rather than correcting them after they occur. This preliminary corrective action eliminates the harmful factor while keeping the system relatively simple.
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 system effectively compensates for gravity changes, ensuring stable and balanced operations of surgical arm devices even on inclined surfaces, enhancing safety and precision in medical procedures.
Implementation Method 1
a setting unit that sets a computational condition including gravity compensation according to the inclination information
Data Source
AI summary
There is provided a control system for controlling a surgical arm device of a multi-link structure in which a plurality of links is coupled together by a joint unit in a force control mode.In generalized inverse dynamics, the control system sets a motion purpose and a constraint condition in an operation space describing an inertia of force acting on a multi-link structural body and an acceleration of the multi-link structural body, and for implementing an operation space acceleration indicating the motion purpose, calculates a virtual force acting on the operation space on the basis of a motion equation relating to the operation space including a term of an operation space bias acceleration in consideration to gravity compensation according to inclination information of the surgical arm device, and calculates a torque command value for a joint unit on the basis of a real force converted from the virtual force.