Sensorless Occlusion Detection in Fluid Delivery Motors
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Solution Overview
Problem
Existing fluid delivery devices, such as insulin pumps, face challenges in accurately and efficiently delivering medication due to variations in reservoir friction, occlusion detection complexity, and energy inefficiency, which can lead to unreliable and costly designs.
Innovation Solution
Implementing a processor-controlled method using motor position sensors to detect plunger position and occlusions, compensating for friction variations, and optimizing motor control for pulsatile operations with active braking, eliminating the need for additional strain sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If strain sensors are added to detect occlusions and friction, then occlusion detection accuracy improves, but device complexity and cost increase
Solution Approach 1:
The motor serves dual functions: delivering fluid and detecting occlusions/friction through its own operational parameters (current, speed, position). The system uses self-generated data from motor operation to monitor fluid delivery status, eliminating the need for separate strain sensors while maintaining detection accuracy through analysis of motor performance variations
Solution Approach 2:
The motor and its control system are designed to perform multiple functions: fluid delivery, occlusion detection, friction compensation, and flow rate monitoring. By making the motor system universal, the patent eliminates dedicated strain sensors and reduces overall system complexity while maintaining comprehensive monitoring capabilities
2Manufacturing precision
If friction compensation mechanisms are implemented, then delivery accuracy improves, but device complexity increases
Solution Approach 1:
The system continuously monitors motor operational parameters and uses this feedback to dynamically adjust motor commands for friction compensation. By analyzing variations in motor current, speed, and position during operation, the system automatically compensates for friction effects without requiring additional sensors or complex mechanical compensation mechanisms
Solution Approach 2:
The patent replaces mechanical friction compensation mechanisms with electronic control algorithms that analyze motor operational data. Instead of using additional mechanical components or sensors to measure and compensate friction, the system uses software-based analysis of motor performance to achieve the same effect, reducing mechanical complexity
3Reliability
If continuous monitoring of delivery rate is performed, then occlusion detection reliability improves, but energy consumption increases
Solution Approach 1:
The system performs continuous monitoring of delivery rate using data already being collected for motor control operations. By utilizing existing motor position and speed measurements that are continuously updated during normal operation, the system achieves continuous occlusion detection without requiring additional energy-consuming measurement systems
Solution Approach 2:
The motor control system generates operational data that is simultaneously used for both motor control and occlusion detection purposes. This self-service approach allows the system to maintain continuous monitoring capability using the same computational resources already allocated for motor operation, avoiding additional energy consumption
Data Source
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AI summary
A processor-implemented method comprises obtaining a baseline coefficient of variation of delivery rate of a fluid delivery device; obtaining an instantaneous delivery rate of the fluid delivery device during a motor stroke, the motor stroke including a plurality of motor steps; determining a current minimum delivery rate of the fluid delivery device based on the instantaneous delivery rate and a previous minimum delivery rate of the fluid delivery device; storing the current minimum delivery rate in a buffer; determining a current coefficient of variation of delivery rate of the fluid delivery device based on data in the buffer; and determining whether an occlusion has occurred based on one or more threshold values and a rate of change of the current coefficient of variation of delivery rate with respect to the baseline coefficient of variation of delivery rate.