| CPC A61M 5/31568 (2013.01) [A61M 5/3155 (2013.01); A61M 5/3157 (2013.01); A61M 5/31585 (2013.01); G01C 19/00 (2013.01); G01P 15/18 (2013.01); G16H 20/17 (2018.01); G16H 40/40 (2018.01); G16H 40/63 (2018.01); G16H 40/67 (2018.01); G16H 50/70 (2018.01); A61M 2005/3126 (2013.01); A61M 2205/3327 (2013.01); A61M 2205/52 (2013.01); A61M 2205/581 (2013.01); A61M 2205/582 (2013.01); A61M 2205/8206 (2013.01)] | 14 Claims |

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1. A method of determining a dose of a variable-dose injection device with feedback means generating a number of feedback events proportionate to the dose, comprising:
measuring, by a first feedback sensor, a first signal comprising a first signal peak related to a feedback event, wherein the first feedback sensor is configured as a multi-axis gyroscope;
detecting the first signal peak in the first signal;
selecting an evaluation interval comprising the detected first signal peak;
deriving, from the first signal limited to the evaluation interval, a feature of the feedback event, wherein deriving the feature comprises:
calculating, for each axis of the gyroscope, a correlation value of a test signal with a single-axis gyroscope signal, and adding the correlation values; or
calculating, for each axis of the gyroscope, a sum of absolute derivatives of a single-axis gyroscope signal, and adding the sums;
identifying, from the derived feature, the feedback event as an expel feedback event; and
counting the number of identified expel feedback events to determine an expelled dose.
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