Tension Control for Multi-Joint Medical Instruments
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current robotic medical instruments with compliant transmission systems face challenges in precise control due to non-negligible compliance between proximal actuators and remote actuated elements, making it difficult to model the relationship between actuator positions and joint positions, which affects the accuracy of instrument movement.
Innovation Solution
The control system determines the forces applied through transmission systems by measuring the current and desired configurations of the instrument, allowing for precise control even in systems with non-rigid transmission, by calculating the required joint torques and actuator forces based on the differences between actual and desired configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If compliant transmission systems are used in robotic medical instruments, then flexibility and adaptability in tissue interaction are improved, but control precision and accuracy deteriorate due to non-negligible compliance between actuators and actuated elements
Solution Approach 1:
The patent implements a control system that continuously measures the actual configuration of the instrument and uses this feedback to calculate and adjust actuator forces. The system determines current configuration, compares it with desired configuration, and dynamically adjusts tendon tensions to compensate for compliance effects, thereby maintaining control precision while allowing flexible transmission systems
Solution Approach 2:
The patent dynamically changes control parameters (actuator forces and tensions) based on the difference between current and desired configurations. By adjusting these parameters in real-time according to measured configuration differences, the system compensates for compliance and maintains precise control despite using flexible transmission systems
2Device complexity
If fixed relationships between actuator positions and joint positions are assumed, then control complexity is reduced, but control accuracy deteriorates in systems with compliant transmission
Solution Approach 1:
Instead of relying on fixed kinematic relationships, the system uses feedback from configuration measurements to determine actuator forces. This eliminates the need for complex compliance modeling while maintaining accuracy through dynamic adjustment based on actual instrument state
Solution Approach 2:
The patent replaces traditional position-based control with force-based control. Instead of directly controlling joint positions through rigid mechanical relationships, the system controls actuator forces and uses these forces to achieve desired configurations, substituting mechanical precision with controlled compliance
Data Source
AI summary
An instrument system includes actuators, an instrument, and a control system. The instrument includes joints and transmission systems that couple the joints with the actuators. A first joint is distal to a second joint, a first transmission system passes through the second joint to couple to the first joint, and a second transmission system couples to the second joint. The control system is programmed to determine a first tension to be applied by the first transmission system, determine a first estimate of an interaction response that results at the second joint from applying the first tension by the first transmission system, determine a second tension to be applied by the second transmission system based on a first set of parameters, the first set of parameters including the first estimate, and command the actuators such that the first and second transmission systems apply the first and second tensions, respectively.