Capacitive Joystick Interlock for Fault-Safe Catheter Control
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Solution Overview
Problem
Robotic catheter procedure systems face issues with joystick failures, leading to unintended actuation of medical devices when the user is not touching the joystick, which can cause unexpected movement or actuation of percutaneous devices during procedures.
Innovation Solution
An interlocking system for joysticks using capacitive touch detection to prevent device movement unless the user is actively touching the joystick, employing a capacitive touch detection circuit and signal enable circuit to ensure safe and controlled operation by routing appropriate voltage signals based on touch detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a joystick is used to control percutaneous devices in a robotic catheter procedure system, then the physician can precisely steer the guide wire and catheters, but the joystick may experience faults or failures that cause unintended actuation or unexpected movement of the percutaneous device when the user is not touching the joystick
Solution Approach 1:
A capacitive sensor serves as an intermediary between the joystick and the control system. The sensor detects whether a user is touching the joystick by measuring capacitive coupling, and only allows control signals to pass through when touch is detected. This intermediary layer prevents unintended actuation from joystick faults while maintaining precise control when properly operated.
Solution Approach 2:
The system continuously monitors the capacitive state of the joystick to provide feedback on whether the joystick is being actively touched. This feedback mechanism enables the system to dynamically enable or disable device actuation based on user presence, creating a safety loop that prevents unintended movement from faults while allowing precise control during normal operation.
2Reliability
If a fault detection system is added to the joystick interface to prevent unintended actuation, then safety is improved, but the system complexity increases
Solution Approach 1:
The capacitive sensor acts as a simple intermediary component that adds minimal complexity to the joystick interface. Rather than implementing complex fault detection algorithms or multiple sensors, the system uses the inherent capacitive properties of the joystick surface to detect user touch, providing safety through a single, elegant sensing mechanism.
Solution Approach 2:
The joystick surface itself provides the sensing function through its capacitive properties. The human body's electrical properties create a detectable capacitive coupling when touching the joystick, allowing the system to self-detect user presence without requiring additional complex sensing infrastructure. The joystick essentially serves its own safety function through its physical characteristics.
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 interlocking system provides a single fault-safe joystick interface, rapidly disabling device motion when the user is not touching the joystick, thereby preventing unintended actuation and ensuring precise control during catheter procedures.
Implementation Method 1
A capacitive touch detection circuit is configured to detect changes in capacitance from a user touching a joystick and to generate a touch output signal
Data Source
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AI summary
An interlocking system for a joystick in a catheter procedure system includes a joystick configured to generate a first voltage output signal based on a linear activation of the joystick and a second voltage output signal based on a rotational activation of the joystick. A joystick cover is disposed over the joystick and includes an upper portion having an electrode plating on an inner surface of the upper portion and a lower portion having an inner surface. A capacitive touch detection circuit is coupled to the electrode plating of the upper portion of the joystick cover and is mounted on the inner surface of the lower portion of the joystick cover. The capacitive touch detection circuit is configured to detect a proximal change in capacitance in the electrode plating of the upper portion of the joystick cover and to generate a touch output signal to indicate whether a change in capacitance has been detected. A signal enable circuit is coupled to the joystick and the capacitive touch detection circuit and is configured to generate a linear enable voltage output signal and a rotational enable voltage output signal based on whether a change in capacitance has been detected.