Insulin Pump Motor Control for Reservoir Friction Compensation
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Solution Overview
Problem
Existing insulin pumps face challenges in accurately delivering insulin due to variations in reservoir friction, which can lead to energy inefficiency, delivery errors, and increased complexity and cost from the use of additional sensors, and difficulty in detecting occlusions.
Innovation Solution
The method involves controlling the motor of the insulin pump to perform pulsatile operations with adjustable stroke sizes and using motor position sensors for plunger detection and occlusion detection, eliminating the need for additional strain or pressure sensors, and implementing calibration techniques to compensate for reservoir friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional strain or pressure sensors are used to detect reservoir friction and occlusions, then detection sensitivity improves, but device complexity and cost increase
Solution Approach 1:
The patent extracts the occlusion detection function from dedicated strain or pressure sensors and relocates it to the motor controller by analyzing motor current and rotation characteristics. This eliminates the need for additional sensors while maintaining detection capability.
Solution Approach 2:
The motor itself serves dual purposes: delivering insulin and detecting occlusions. By monitoring the motor's own electrical characteristics (current, voltage, rotation speed) during operation, the system self-diagnoses occlusion conditions without requiring external sensing components.
2Manufacturing precision
If motor drive voltage or duty cycle is increased to compensate for reservoir friction, then delivery accuracy improves, but energy consumption increases
Solution Approach 1:
The system performs preliminary characterization of reservoir friction during an initialization phase before actual insulin delivery. By measuring the motor characteristics during this preliminary phase, the controller pre-calculates compensation parameters that will be applied during subsequent delivery operations, ensuring accuracy without excessive energy use.
Solution Approach 2:
The motor drive parameters (voltage, duty cycle) are dynamically adjusted based on real-time feedback from motor current and rotation measurements. The system continuously adapts the drive signal to maintain optimal delivery accuracy while minimizing energy consumption, rather than using fixed high-power settings.
3Manufacturing precision
If calibration techniques are implemented to compensate for reservoir friction, then delivery accuracy improves, but processing time increases
Solution Approach 1:
The calibration process is performed preliminarily during device initialization or reservoir installation, before actual insulin delivery begins. This allows the system to characterize reservoir friction and compute compensation parameters in advance, so that during therapeutic delivery, only simple real-time adjustments are needed rather than repeated complex calculations.
Solution Approach 2:
The patent replaces complex mechanical friction measurement techniques with electrical measurements of motor current and voltage. By using electrical characteristics to infer mechanical friction conditions, the system reduces computational complexity and processing time while maintaining delivery accuracy.
Data Source
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AI summary
A processor-implemented method includes obtaining motor rotation data associated with a motor that is configured to rotate in strokes to drive a plunger within a reservoir in a fluid delivery device, the motor rotation data indicating time intervals between changes of position of the motor; for each stroke of a first plurality of strokes of the motor, determining an instantaneous delivery rate during one or more steps of the stroke based on the motor rotation data, and storing the instantaneous delivery rate to a buffer; determining a pre-compensation delivery rate of the fluid delivery device based on data in the buffer; and determining, in response to the pre-compensation delivery rate being lower than a pre-determined delivery rate, a first adjustment to at least one of a motor drive voltage level or a motor drive duty cycle of a drive signal of the motor.