In order to solve problem that during measurement of motion parameters of automata underwater

core coil will affect measurement precision by generating eddy currents

propose a new method to improve structure of permanent-magnet induction velocity measurement sensor based on electromagnetic induction. The iron core is replaced by epoxy resin board

this sensor is tightly wrapped a layer of coil as speed coil

multi-turn winded with equal interval between positive and negative by silk envelope wire is taken as displacement coil on the surface of the speed coil; besides permalloy stands between speed coil and epoxy resin board to ensure the high-permeability of coil core

and increase sensitivity of the sensor; signal conditioning circuit is designed and encapsulated within the sensor. After experimental verification

the sensitivity of the improved sensor is higher and dynamic characteristics is better

the test signal is more accurate

reflect movement rule of automata more truly.