Flexible Catheter Control Under Abnormal Articulation Sensor Signals
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Solution Overview
Problem
Existing systems face challenges in controlling flexible medical devices due to temporary fault conditions that cause errors in articulation sensor feedback signals, leading to unsuitable closed-loop control, particularly during mechanical vibrations during insertion or removal of tools.
Innovation Solution
A control method that switches to an alternate feedback signal based on actuator sensor signals, processed by a simulation model of the flexible catheter to estimate actual articulation, ensuring stable control during fault conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If articulation sensor feedback signals are used for closed-loop control, then control precision is improved, but system reliability deteriorates due to temporary fault conditions and mechanical vibrations
Solution Approach 1:
The patent introduces a simulation model as an intermediary between the actuator sensor signals and the control system. When articulation sensor signals become unreliable due to faults or vibrations, the simulation model processes actuator sensor signals to generate estimated articulation values, serving as a mediator to maintain control reliability without sacrificing precision
Solution Approach 2:
The system performs preliminary action by pre-processing actuator sensor signals through the simulation model to generate estimated articulation values before the actual articulation sensor signals become unreliable. This allows the system to switch to the estimated values proactively, preventing control disruptions rather than reacting after faults occur
2Measurement precision
If articulation sensor signals are used during tool insertion/removal, then control accuracy is maintained, but control stability deteriorates due to mechanical vibrations
Solution Approach 1:
The system implements a dual feedback mechanism: normally using articulation sensor feedback for high-precision control, and switching to simulation model-based feedback from actuator sensor signals when vibrations occur. The simulation model provides a stable alternative feedback source that is immune to vibration-induced noise, maintaining control stability while preserving accuracy through the model's predictive capabilities
3Reliability
If alternate feedback control mode is activated, then control stability is improved during faults, but device complexity increases
Solution Approach 1:
The control system is designed to be dynamic, automatically switching between normal articulation sensor feedback mode and alternate actuator sensor feedback mode based on real-time conditions. The simulation model is only activated when needed, making the system adaptable to fault conditions without permanently increasing complexity. This dynamic approach maintains simplicity during normal operation while providing robustness when required
Data Source
AI summary
A computer-assisted medical system includes a flexible catheter configured to articulate along a degree of freedom, an actuator disposed at a proximal portion of the flexible catheter, an actuator sensor, and an articulation sensor. The actuator is configured to actuate the flexible catheter along the degree of freedom, the actuator sensor is configured to provide actuator sensor signals representing movement of the actuator, and the articulation sensor is configured to provide articulation sensor signals representing articulation of the flexible catheter. The computer-assisted medical system further includes a controller coupled to the actuator and configured to, based on detecting an abnormality in a first articulation sensor signal, determine an articulation estimate of the flexible catheter based on a model of the flexible catheter applied to a first actuator sensor signal, and control the actuator based on the articulation estimate.