Air detection system and method for detecting air in a pump of an infusion system
Various systems and methods for detecting air in a chamber of an infusion system are disclosed. In one embodiment, a determination is made that air is contained in the chamber on the basis of a change in the average force exerted against the plunger utilizing a derivative spike for event detection and a systematic reduction in the average force to confirm the nature of the change. In another embodiment, a determination is made that the chamber contains air when a difference between the current force profile and a baseline force profile crosses a threshold. In an additional embodiment, a force profile is classified as being an air force profile or a liquid force profile based on extracted features of the force profile.
1. A method for detecting air in a chamber of an infusion system comprising:
moving a plunger against the chamber containing fluid;
detecting a force acting on the plunger as it moves against the chamber;
preprocessing a force profile based on the detected force acting on the plunger;
extracting features from the force profile; and
classifying the force profile as being an air force profile or a liquid force profile based on the extracted features,
wherein the preprocessing comprises: acquiring the force profile; re-sampling the force profile for a set of angles; selecting a sub-set of angles for the force profile; and calculating a derivative of the force profile based on the force profile at the sub-set of angles.
2. The method of claim 1 , wherein the classification of the force profile as being the air force profile or the liquid force profile is done without applying signal normalization to normalize to a baseline force profile.
3. The method of claim 1 , wherein the pre-processing comprises: applying a low pass filter to the force profile; applying a range limit to the force profile; and calculating a difference between the force profile and a baseline or mean force profile.
4. The method of claim 1 , wherein the extraction of the features comprises calculating scores of the force profile or applying a linear discriminate analysis to the force profile.
5. A system for detecting air in a chamber of an infusion system, the system comprising one or more hardware processors configured to:
detect a force acting on a plunger as it moves against the chamber containing fluid;
preprocess a force profile based on the detected force acting on the plunger;
extract features from the force profile; and
classify the force profile as being an air force profile or a liquid force profile based on the extracted features,
wherein the preprocessing comprises: acquiring the force profile; re-sampling the force profile for a set of angles; selecting a sub-set of angles for the force profile; and calculating a derivative of the force profile based on the force profile at the sub-set of angles.
6. The system of claim 5 , wherein the classification of the force profile as being the air force profile or the liquid force profile is done without applying signal normalization to normalize to a baseline force profile.
7. The system of claim 5 , wherein the pre-processing comprises: applying a low pass filter to the force profile; applying a range limit to the force profile; and calculating a difference between the force profile and a baseline or mean force profile.
8. The system of claim 5 , wherein the extraction of the features comprises calculating scores of the force profile or applying a linear discriminate analysis to the force profile.
9. A non-transitory storage medium comprising instructions when executed by one or more hardware processors cause for detecting air in a chamber of an infusion system, the one or more hardware processors configured to implement a process comprising:
detecting a force acting on a plunger as it moves against the chamber containing fluid;
preprocessing a force profile based on the detected force acting on the plunger; extracting features from the force profile; and
classifying the force profile as being an air force profile or a liquid force profile based on the extracted features,
wherein the preprocessing comprises: acquiring the force profile; re-sampling the force profile for a set of angles; selecting a sub-set of angles for the force profile; and calculating a derivative of the force profile based on the force profile at the sub-set of angles.
10. The non-transitory storage medium of claim 9 , wherein the classification of the force profile as being the air force profile or the liquid force profile is done without applying signal normalization to normalize to a baseline force profile.
11. The non-transitory storage medium of claim 9 , wherein the preprocessing comprises: applying a low pass filter to the force profile.
12. The non-transitory storage medium of claim 9 , wherein the preprocessing comprises: applying a range limit to the force profile.
13. The non-transitory storage medium of claim 9 , wherein the preprocessing comprises: calculating a difference between the force profile and a baseline or mean force profile.
14. The non-transitory storage medium of claim 9 , wherein the extraction of features comprises calculating scores of the force profile or applying a linear discriminate analysis to the force profile.