Surgical Arm Feedback Control for External Force Compensation
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Solution Overview
Problem
Existing arm devices for surgery assistant robots in endoscopic surgery either allow the surgical tool's position and posture to change with externally applied forces, leading to loads on the subject's body, or maintain a fixed position but may apply erroneous forces due to positioning errors.
Innovation Solution
An arm device with a joint portion that can rotate in response to externally applied forces, an actuator to generate driving forces, an estimator to calculate external forces, a calculator to determine necessary driving forces based on the surgical tool's weight and estimated forces, and a controller to adjust the actuator's driving forces accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the arm device allows the surgical tool's position and posture to change with externally applied forces, then the device can adapt to external forces, but a load is imposed on the subject's body
Solution Approach 1:
The control device estimates the external force applied to the surgical tool and uses this information to adjust the actuator's driving force. This feedback mechanism allows the system to respond to external forces while compensating for them, thereby reducing the load transmitted to the subject's body.
Solution Approach 2:
The system dynamically changes the driving force parameter of the actuator based on the estimated external force. By adjusting the driving force in real-time according to the external force magnitude, the system maintains adaptability while minimizing the harmful load on the subject's body.
2Stability of the object's composition
If the arm device maintains a fixed position and posture of the surgical tool, then the position stability is improved, but erroneous forces may be applied due to positioning errors
Solution Approach 1:
The control device continuously estimates the external force and compares it with the current driving force to determine the necessary adjustment. This feedback loop enables the system to maintain stable positioning while compensating for positioning errors by adjusting the driving force according to the estimated external force.
Solution Approach 2:
The system transitions from a static fixed-position approach to a dynamic approach where the driving force is continuously adjusted based on real-time external force estimation. This dynamic adjustment allows the system to maintain position stability while adapting to external conditions, preventing erroneous force application.
3Manufacturing precision
If actuators are provided to all joints including joints forming a gimbal, then the position and posture control precision is improved, but the device complexity increases
Solution Approach 1:
The control device estimates the external force based on information from the actuators and uses this information to control the actuators themselves. This self-service approach allows the system to achieve precise control with the provided actuators without requiring additional complex components.
Solution Approach 2:
The actuators serve multiple functions: they provide the driving force for position and posture control, and their load information is used by the control device to estimate external forces. This multi-functionality reduces the need for separate sensing components, thereby managing device complexity while maintaining control precision.
Data Source
AI summary
An arm device includes a joint portion configured to be rotated to thereby change a position and/or a posture of a surgical tool, and an actuator configured to generate a driving force that rotates the joint portion, and to allow a rotation of the joint portion in accordance with an externally applied force. Moreover, the arm device is configured to estimate an external force applied to the surgical tool, to obtain a value of a driving force of the actuator based on a weight of the surgical tool and the external force, and to control the actuator based on a value of the driving force.