Infusion Motor Unintended Motion Detection via Periodic Sensing

Solution Overview

Problem

Portable infusion devices with BLDC motors are susceptible to unintended rotor motion due to external magnetic interference, which can lead to uncontrolled operation and inefficiency, as they do not have a stator magnetic field to oppose rotor movement when idle.

Innovation Solution

A control system that periodically enables a sensing arrangement to detect potential unintended motion of the motor by monitoring the rotor's magnetic field, differentiating between actual rotation and magnetic field boundary alignment errors, and initiating continuous monitoring if necessary to determine if the motion is actionable.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If BLDC motor with permanent magnets is used, then motor efficiency and compact size are improved, but susceptibility to magnetic interference and uncontrolled rotor displacement increases

Engineering Contradiction:

Improvemotor efficiencyVSAvoidrotor control stability

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The system performs preliminary detection of unintended rotor motion during idle periods before actual medication delivery occurs. By monitoring the rotor position during idle time when the motor is not actively driving, the system can detect and correct magnetic interference effects before they impact medication delivery, preventing potential errors in advance.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system continuously monitors rotor position during idle periods and provides feedback to the control system. When unintended rotor displacement is detected, the system can adjust or compensate for the motion, ensuring that the rotor returns to or remains at the correct position before the next medication delivery cycle begins.

Inventive Principle:

Principle #23Feedback

2Reliability

If sensing arrangement is continuously enabled to detect rotor motion, then detection reliability is improved, but power consumption increases

Engineering Contradiction:

Improvemotion detection accuracyVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

Instead of continuously enabling the sensing arrangement, the system periodically samples the rotor position during idle periods. The controller activates the sensor only at specific intervals to check for unintended motion, rather than maintaining continuous monitoring. This periodic sampling maintains detection capability while significantly reducing power consumption during idle time.

Inventive Principle:

Principle #19Periodic action

3Use of energy by moving object

If motor is kept idle to conserve power, then power consumption is reduced, but susceptibility to magnetic interference and uncontrolled motion increases

Engineering Contradiction:

Improvepower consumptionVSAvoidrotor position stability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The system performs preliminary detection of unintended rotor motion during idle periods before actual medication delivery occurs. By monitoring the rotor position during idle time when the motor is not actively driving, the system can detect and correct magnetic interference effects before they impact medication delivery, preventing potential errors in advance.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system continuously monitors rotor position during idle periods and provides feedback to the control system. When unintended rotor displacement is detected, the system can adjust or compensate for the motion, ensuring that the rotor returns to or remains at the correct position before the next medication delivery cycle begins.

Inventive Principle:

Principle #23Feedback

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

Effectively detects and mitigates unintended motor rotation, preventing overdelivery or underdelivery of medication by adjusting operation and alerting the user, while conserving power by only consuming energy during necessary monitoring periods.

Implementation Method 1

The sensing arrangement is coupled to the motor and includes one or more sensors configured to provide output indicative of a detected magnetic field of the rotor magnet when the sensing arrangement is enabled

Methodology Applied

Scientific EffectMagnetic field detection: Magnetic Field

Data Source

PatentUS9795732B2Detecting unintentional motor motion and infusion device incorporating same

Publication Date: 2017.10.24 MEDTRONIC MINIMED INC

AI summary

Apparatus are provided for infusion devices and related systems and operating methods. An exemplary system includes a motor, a sensing arrangement coupled to the motor to provide output indicative of a detected characteristic of the motor when the sensing arrangement is enabled, and a module coupled to the sensing arrangement to periodically enable the sensing arrangement while the motor is idle and detect potential unintended motion of the motor based on the output from the sensing arrangement while periodically enabling the sensing arrangement. In some embodiments, the motor includes a rotor configured such that its rotation provides translational displacement of a plunger in a fluid reservoir, and the sensing arrangement includes one or more sensors configured to provide output indicative of a detected magnetic field of the rotor magnet.