Differential Optical sensor for measuring small linear displacement

Measurement of the mechatronic module small linear displacement usually is a challenge for several reasons, the main of which is the requirement of the sensor minimal weight and size as well as the requirement to its output characteristics that should be linear to maintain good measurement accuracy displacement. The article offers a constructive model of an optical sensor based on measurement of the difference of output signals of two optocouples recording displacement of the signal element. Installation of two optocouplers justifies the need to achieve invariability of the measured movement to changes of the parameters of the electromechanical system parameters in which it is integrated, because this requirement is especially important in the mechatronic module series. It considers a circuit diagram of conversion and conditioning of the optocouples' output signals. The structural model of a differential sensor offered in the article has been implemented by 3d printing and, in conjunction with the basic circuit diagram, used as an element of the automatic control system for measuring of the ventilator exhalation valve movement. The author carried out experimental research of the offered sensor which prove its high competitive power among other types of sensors by such criteria as linearity of the output characteristic, error-rate performance and small dimensions. The work was supported by the Act 211 Government of the Russian Federation, contract No 02.A03.21.0011.