Insulin Pump Plunger Detection via Motor Rotation Variability

Solution Overview

Problem

Existing insulin pumps face challenges in accurately and efficiently delivering insulin due to variations in reservoir friction, plunger detection, and occlusion detection, which can lead to energy inefficiency, increased complexity, and higher costs, particularly when using additional sensors like strain or pressure sensors.

Innovation Solution

The method employs motor position sensors to detect the plunger and occlusion by analyzing motor rotation time variations, using statistical filters to establish baseline and moving coefficients of variation, and adjusting motor drive parameters to compensate for friction, without the need for additional sensors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If additional sensors (strain or pressure sensors) are used to detect plunger position and occlusion, then detection accuracy is improved, but device complexity and cost increase

Engineering Contradiction:

Improveplunger detection accuracyVSAvoidsensor system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The motor position sensor serves multiple functions: it detects plunger position during reservoir setup, monitors motor rotation for occlusion detection, and tracks delivery volume. This eliminates the need for separate strain or pressure sensors, reducing device complexity while maintaining detection accuracy.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The motor's own position sensor is used to detect conditions (plunger position, occlusion) that would traditionally require separate sensing systems. The system uses the motor's operational data (rotation time, position changes) to self-diagnose and detect critical states without external sensors.

Inventive Principle:

Principle #25Self-service

2Measurement precision

If additional sensors (strain or pressure sensors) are used to detect plunger position and occlusion, then detection accuracy is improved, but manufacturing cost increases

Engineering Contradiction:

Improveocclusion detection accuracyVSAvoidmanufacturing cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The motor position sensor serves multiple functions: it detects plunger position during reservoir setup, monitors motor rotation for occlusion detection, and tracks delivery volume. This eliminates the need for separate strain or pressure sensors, reducing device complexity while maintaining detection accuracy.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The motor's own position sensor is used to detect conditions (plunger position, occlusion) that would traditionally require separate sensing systems. The system uses the motor's operational data (rotation time, position changes) to self-diagnose and detect critical states without external sensors.

Inventive Principle:

Principle #25Self-service

3Manufacturing precision

If motor rotation time variations are analyzed to compensate for friction, then delivery accuracy is improved, but energy consumption increases

Engineering Contradiction:

Improveinsulin delivery accuracyVSAvoidmotor energy consumption

Core Design Contradiction:

Manufacturing precisionVSUse of energy by moving object

Solution Approach 1:

The system continuously monitors motor rotation time and compares it against expected values to detect friction variations. When friction is detected, the control system adjusts motor drive parameters in real-time to compensate, maintaining delivery accuracy while optimizing energy usage through adaptive control rather than continuous high-power operation.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The motor drive parameters are dynamically adjusted based on real-time friction detection from rotation time analysis. This allows the system to optimize energy consumption by applying only the necessary force to overcome actual friction conditions, rather than using fixed high-power settings.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentEP4691517A1Method of sensor-less plunger detection during insulin reservoir setup

Publication Date: 2026.02.11 MEDTRONIC MINIMED INC

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AI summary

A processor-implemented method includes obtaining motor rotation data associated with a motor that is configured to rotate steadily to actuate a drive system for driving a plunger of a reservoir in a fluid delivery device; for each rotation of a plurality of rotations of the motor, based on a measured rotation time of the rotation of the motor and a previous maximum rotation time of the motor, determining a current maximum rotation time of the motor and storing the current maximum rotation time in a buffer; determining a coefficient of variation of motor rotation time based on data in the buffer; determining a change of the coefficient of variation of motor rotation time with respect to a baseline coefficient of variation of motor rotation time; and determining whether the plunger is detected based on a comparison of the change and a threshold value.