Piezo-electric Pump Control for Power Reduction
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Solution Overview
Problem
Portable medical devices like insulin pumps face significant power consumption challenges, leading to reduced battery life, and existing systems often over-actuate the pumping membrane to ensure precision and reliability, resulting in increased power usage.
Innovation Solution
A control system that minimizes the driving voltage of a piezoelectric actuator using embedded sensors to ensure the pumping membrane reaches defined positions with minimal energy, determining the optimal actuation voltage through a learning process to reduce power consumption and enhance mechanical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the maximum voltage is applied to the piezoelectric actuator to compensate for misalignments and ensure consistent pumped volume, then the pumping precision and reliability are improved, but the power consumption increases
Solution Approach 1:
The patent employs feedback control by using sensors to detect the actual position of the pumping membrane and comparing it with the target position. The control unit adjusts the actuator voltage based on this feedback, reducing the voltage from the maximum value when the membrane reaches the target position, thus lowering power consumption while maintaining pumping precision.
Solution Approach 2:
The patent dynamically changes the actuator voltage parameter during operation. Instead of maintaining maximum voltage throughout the actuation cycle, the control unit reduces the voltage parameter once the membrane reaches the target position, optimizing the balance between achieving sufficient displacement for precise pumping and minimizing energy consumption.
2Manufacturing precision
If a safety margin is applied to the actuation voltage to account for tolerances and environmental variations, then the consistency of pumped volume is improved, but the power consumption increases
Solution Approach 1:
The feedback mechanism allows the system to compensate for tolerances and environmental variations without requiring excessive safety margins in the actuation voltage. By continuously monitoring the membrane position and adjusting the voltage accordingly, the system maintains consistent pumped volume while minimizing energy consumption.
Solution Approach 2:
The patent transitions from a static safety margin approach to a dynamic voltage adjustment approach. The actuator voltage is dynamically adjusted during the actuation cycle based on real-time feedback, allowing the system to adapt to variations in tolerances and environmental conditions without maintaining a constant excessive safety margin.
3Reliability
If the pumping membrane is over-actuated against mechanical stops to ensure repeatability, then the pumping precision is improved, but the power consumption increases
Solution Approach 1:
The feedback control system monitors the membrane position and detects when the mechanical stops are approached or reached. The control unit adjusts the actuator voltage to prevent excessive over-actuation, ensuring the membrane reaches the target position with sufficient precision while minimizing the energy consumed by excessive actuation.
Solution Approach 2:
The patent applies partial actuation rather than full over-actuation. By using feedback information, the control unit determines the minimum necessary voltage to achieve the target position, avoiding the excessive action of over-actuating against mechanical stops and thereby reducing power consumption while maintaining required repeatability.
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 reduces power consumption by applying the minimum necessary voltage, extends battery life, and improves the reliability of the actuator by identifying optimal actuation conditions, thereby enhancing the overall efficiency and longevity of the pumping mechanism.
Implementation Method 1
A piezoelectric actuator (6), which actuates the pumping membrane (1)
Data Source
Figure 1A~3
Figure 4~6
Figure 7~8
AI summary
The method for actuating a pumping device with an optimal driving voltage, wherein the pumping device comprises at least a pumping chamber (4) having a pumping membrane (1), an inlet chamber (3) and an outlet chamber (5), a voltage controlled actuator (6) connected to said pumping membrane (1 ), said pumping membrane reaching at least one stop position defined by a mechanical stop (2) during a pumping stroke, at least one sensor for determining whether the pumping membrane has reached said at least one mechanical stop (2); said method comprising a learning phase and a working phase, wherein the learning phase comprises at least the following steps -) actuation of the pumping membrane (1 ) by applying a predetermined actuation voltage Vact to the actuator (6), said voltage being either high enough for said pumping membrane (1 ) to reach said position in an over-actuation step or low enough for said pumping membrane (1 ) not to reach said mechanical stop (2) position in an under-actuation process; -) after the over-actuation step, decreasing the applied actuation voltage until it is determined that the pumping membrane (1 ) has left said mechanical stop (2) position and storing as the optimal voltage Vact optimal the lowest applied voltage value before the pumping membrane (1 ) has left said mechanical stop (2) position; or -) in the under-actuation step, increasing the applied voltage until it is determined that the pumping membrane (1 ) has reached said mechanical stop (2) position and storing as the optimal voltage Vact optimal the lowest applied voltage value when the pumping membrane (1 ) has reached said mechanical stop (2) position; -) actuating the pumping device in the working phase with the determined optimal voltage value Vact optimal.