US Patent 10549034 Actuation step failure handling

An apparatus for automatic ejection of a fluid includes a drive train for automatically ejecting the fluid from a fluid reservoir through an ejection channel, and a control unit for controlling the apparatus. The control unit is configured to detect failures of drive train actuation steps, during which the drive train is actuated for priming or fluid dose ejection. The control unit is further configured to control the apparatus as a function of an actuation step failure number. The actuation step failure number is the number of failed drive train actuation steps since the last successful drive train actuation step.