Insulin Reservoir Friction Compensation Using Motor Stroke Feedback
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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 system employs pulsatile motor operations with adjustable voltage levels and duty cycles, uses motor position sensors for plunger detection and occlusion detection, and compensates for reservoir friction during setup, eliminating the need for additional strain sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional strain sensors are used to detect reservoir friction and occlusions, then detection sensitivity and reliability improve, but device complexity and cost increase
Solution Approach 1:
The motor serves multiple functions: it drives the plunger and simultaneously acts as a sensor through back-EMF measurement. The motor's electrical characteristics change in response to mechanical load variations, allowing the system to self-diagnose friction and occlusion conditions without additional strain sensors.
Solution Approach 2:
The patent replaces mechanical strain sensors with an electrical sensing approach. By measuring the motor's back-EMF and electrical characteristics, the system detects mechanical conditions (friction, occlusion) through electrical parameters, eliminating the need for separate mechanical sensing components.
2Manufacturing precision
If motor voltage and duty cycle are continuously adjusted to compensate for friction, then delivery accuracy improves, but energy consumption increases
Solution Approach 1:
The system continuously measures the motor's back-EMF and electrical characteristics to determine actual delivery rate, compares it with the commanded rate, and adjusts voltage and duty cycle accordingly. This closed-loop feedback ensures accurate delivery while optimizing energy use by making adjustments only when necessary.
Solution Approach 2:
The motor operating parameters (voltage, duty cycle) are dynamically adjusted based on real-time feedback from back-EMF measurements. The system adapts to changing friction conditions and delivery requirements, optimizing the balance between delivery accuracy and energy consumption throughout the reservoir depletion process.
3Loss of energy
If motor operations are optimized for energy efficiency, then energy consumption decreases, but delivery rate control precision worsens
Solution Approach 1:
By continuously measuring back-EMF and electrical characteristics, the system precisely determines the actual delivery rate regardless of operating conditions. This precise measurement enables accurate control even when operating in energy-efficient modes with variable voltage and duty cycle settings.
Solution Approach 2:
The system changes motor operating parameters (voltage, duty cycle, frequency) based on reservoir friction levels and delivery requirements. By optimizing these parameters dynamically, the system maintains delivery precision across different operating modes while minimizing energy consumption.
Data Source
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.