Adaptive Valve Control for Precise Pressure Trajectory Tracking
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Solution Overview
Problem
Control units for valves in fluid communication systems face challenges in precise control, particularly when following arbitrary pressure trajectories or experiencing rapid pressure changes, due to disturbance forces like actuator shaft-bearing friction and sudden pressure events, leading to inaccuracies, oscillations, and instability, especially in nonlinear systems with varying patient dynamics.
Innovation Solution
A system comprising a flow sensor, pressure sensor, adaptive controller, position controller, and valve actuator that determines a desired flow and position based on measured and target pressures, reducing flow error and applying actuating forces to accurately control valve position and fluid flow, thereby rejecting external disturbing forces and maintaining precise pressure tracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If force control is used for valve control, then the valve can respond to control signals, but precision in following pressure trajectory deteriorates due to disturbance forces
Solution Approach 1:
The patent implements a feedback control mechanism where the actual pressure is continuously measured and compared with the target pressure trajectory. The controller adjusts the valve actuation based on the pressure error signal, enabling the system to compensate for disturbance forces and maintain accurate pressure tracking despite using force control actuation.
2Stability of the object's composition
If valves are overdamped to avoid chattering and oscillatory perturbations, then stability improves, but response speed deteriorates
Solution Approach 1:
The feedback control system dynamically adjusts valve actuation based on real-time pressure measurements, allowing the use of less damped (faster) valve mechanics while maintaining stability through active control. The controller compensates for oscillations and chattering by continuously correcting the valve position based on pressure error, eliminating the need for excessive mechanical damping.
3Adaptability or versatility
If ad-hoc control methods are used to accommodate wide range of load dynamics, then adaptability improves, but system complexity and predictability deteriorate
Solution Approach 1:
The patent employs a control system that dynamically adjusts control parameters based on measured pressure and flow conditions. The adaptive controller modifies actuation signals in real-time to accommodate varying patient loads and respiratory dynamics, providing versatility without requiring complex ad-hoc control methods or pre-use calibrations for each patient.
4Device complexity
If linear control methods are used, then simplicity is maintained, but effectiveness deteriorates due to nonlinear pressure-flow relationship
Solution Approach 1:
The feedback control mechanism continuously measures actual pressure and compares it with the target pressure trajectory, generating an error signal that drives the controller. This closed-loop approach compensates for the nonlinear pressure-flow relationship, maintaining accurate pressure control without requiring complex nonlinear control algorithms or pre-calibration procedures.
Data Source
AI summary
A system for controlling a valve disposed in fluid communication with a fluid circuit is provided. The system includes a flow sensor configured to determine a measured flow and a pressure sensor configured to determine a measured pressure of fluid flowing from the fluid circuit to the valve. The system includes an adaptive controller configured to determine a desired flow based at least on the measured pressure, the measured flow, and a target pressure; determine a flow error as a difference between the desired flow and the measured flow; and determine a desired position of the valve based on the flow error, such that the flow error is reduced. The system includes a position controller configured to determine an actuating electric parameter based at least on the desired position and a valve actuator configured to apply an actuating force on the valve based at least on the actuating electric parameter.