Properties of an inductance type sensor for position control of a long stroke actuator

In large actuators for water gate control of hydraulic dams, precise position measurement of the actuator cylinder is very important. An inductance type sensor can be used to measure the position of the actuator cylinder. This paper presents the effects of the slot shape on the properties of the inductance type sensor consisting of a permanent magnet and pick-up coils. The inductance type sensor is able to measure the position of actuator travelling over 10 m with 0.5 mm resolution. Result of the calculation is able to provide the data for choosing the appropriate shape of the slots to produce the proper magnitude of flux linkage and to minimize the mechanical stress imposed on the cylinder.