Dead Band Normalization for Pump Motor Occlusion Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for detecting occlusions in fluid delivery devices, such as infusion pumps, face inaccuracies due to various design and environmental factors affecting motor current and other parameters, leading to false occlusion detection.
Innovation Solution
Implementing dead band normalization by comparing loaded measured data during fluid movement to unloaded measured data when the pump is not moving fluid, to isolate and remove noise factors unrelated to pressure changes, thereby improving the accuracy of occlusion detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If motor current is used to detect occlusion, then occlusion detection capability is provided, but measurement precision deteriorates due to design and environmental factors affecting current demand
Solution Approach 1:
The patent segments the motor operation into two distinct phases: unloaded operation (dead band) where the pump does not move fluid, and loaded operation where fluid is being moved. By separating these phases and comparing measurements between them, the system isolates the effects of design and environmental factors from pressure-related changes, thereby improving occlusion detection accuracy
Solution Approach 2:
The patent introduces unloaded motor current measurements as an intermediary reference that captures the effects of design factors (gearbox efficiency, motor efficiency, magnet angle) and environmental factors (ambient pressure, temperature) without the confounding influence of fluid pressure. This intermediary measurement serves as a baseline for normalizing loaded measurements, enabling more accurate occlusion detection
2Measurement precision
If motor current measurements are taken during fluid movement, then fluid pressure information is obtained, but noise from design and environmental factors reduces measurement precision
Solution Approach 1:
The patent extracts the unwanted noise components (design factors, environmental factors) from the loaded motor current measurements by comparing them against unloaded measurements. The normalization process effectively removes these harmful factors, leaving only the pressure-related signal components that are relevant for occlusion detection
Solution Approach 2:
The patent changes the operating parameter from raw motor current to normalized motor current, where the normalization factor is derived from unloaded measurements. This parameter transformation converts a noisy measurement into a clean signal that accurately reflects pressure changes while being insensitive to design and environmental variations
Data Source
AI summary
Devices and methods are provided to improve accuracy of occlusion detection based on measured data in a fluid delivery device by using dead band normalization of loaded measured data to unloaded measured data. The loaded measured data and unloaded measured data are obtained during the same fluid movement operation or stroke of the fluid delivery device. The dead band normalization can be performed during an aspiration operation or a dispensing operation. An interface in the fluid delivery device that is close to the fluid driving mechanism and that can at least temporarily move under control but without moving fluid can be used to identify when to generate unloaded measured data during a fluid movement operation for dead band normalization of loaded measured data measured during that fluid movement operation.