Voice Coil Stabilization via Motional EMF Feedback
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Solution Overview
Problem
Conventional voice coil motors used in medical ventilators and anesthesia machines face instability issues due to varying breathing patterns, leading to oscillations in flow and pressure, which are difficult to control with existing feedback systems, especially when damping coefficients are constant and do not adjust to changing pressures and flow rates.
Innovation Solution
A device and method that measures the motional electromotive force (EMF) of a voice coil motor, amplifies the signal to create a stabilizing force in the direction of the EMF, and adjusts damping based on pressure and flow conditions, using a sense resistor to measure current or voltage errors and applying pulse-width modulation to optimize damping dynamically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a constant viscous damping coefficient is used to stabilize the voice coil, then oscillations are reduced, but the valve responds slowly to control signals and changes in flow rate
Solution Approach 1:
The patent applies dynamics by making the damping coefficient variable rather than constant. The damping coefficient is dynamically adjusted based on operating conditions (pressure and flow rate) to optimize both stability and response speed. This resolves the contradiction by allowing high damping when stability is needed and low damping when fast response is needed.
Solution Approach 2:
The patent changes the parameter of damping coefficient from a fixed value to a variable parameter that adapts to operating conditions. By modifying this key parameter based on pressure and flow rate measurements, the system achieves both stability and fast response characteristics that cannot be obtained with a constant damping coefficient.
2Stability of the object's composition
If a high damping coefficient is used to stabilize the valve at high pressure, then oscillations are prevented, but the valve responds too slowly for low pressure conditions
Solution Approach 1:
The system dynamically adjusts the damping coefficient based on the operating pressure and flow rate conditions. At high pressure, a higher damping coefficient is applied to prevent oscillations, while at low pressure, the damping coefficient is reduced to allow faster response. This dynamic adaptation resolves the contradiction between stability and response speed across different operating conditions.
Solution Approach 2:
The damping coefficient parameter is changed from a fixed high value to a variable parameter that adapts to pressure and flow rate conditions. This allows the system to optimize performance for both high pressure (stability) and low pressure (response speed) conditions by adjusting the parameter according to actual operating conditions.
3Stability of the object's composition
If pressure or flow feedback is used to stabilize the valve, then oscillations can be controlled, but the system complexity increases and it is difficult to make conclusions about valve movement
Solution Approach 1:
The system uses self-service by utilizing the existing pressure and flow sensors already present in the ventilator system. Instead of adding complex dedicated feedback sensors, the system leverages available measurements and combines them with a simple damping model to achieve stabilization. This reduces system complexity while maintaining effectiveness.
Solution Approach 2:
The patent implements feedback by using pressure and flow measurements to dynamically adjust the damping coefficient. This feedback mechanism is simpler than traditional position or velocity feedback systems because it uses readily available measurements and a computationally simple damping model, avoiding the complexity of additional sensors and complex control algorithms.
4Stability of the object's composition
If friction is used to prevent oscillations, then valve stability improves, but PEEP pressure control becomes inferior
Solution Approach 1:
The patent replaces mechanical friction-based damping with an electronically controlled damping mechanism. By using electronic control to adjust the damping coefficient based on operating conditions, the system achieves stability without the unwanted side effects of friction on PEEP pressure control. This substitution allows independent optimization of both stability and pressure control precision.
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
This approach provides stable and effective control of expiratory pressure and inspiratory flow, ensuring quick and accurate PEEP management across different patient categories and environmental parameters, reducing work of breathing for patients without the need for additional sensors.
Implementation Method 1
a voice coil for providing a motive force
Implementation Method 2
measuring a signal from the voice coil related to a motional electromotive force
Data Source
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AI summary
A device or method for stabilizing a voice coil (20,21,22) is disclosed. The device comprises a voice coil for providing a motive force, and means for measuring a signal (31) from said voice coil related to a motional electromotive force. The device further comprises a unit (32) for controlling an amplification of said signal to create a force in said voice coil in a direction of said motional electromotive force.