A novel velocity sensor based on electromagnetic induction

A novel velocity sensor based on electromagnetic induction was proposed in this paper. It was composed of four small inductor chips with circular symmetrical distribution on the bottom of a printed circuit board (PCB) and an elastic body with a permanent magnet embedded into on the top of the PCB. The output voltage of each inductor chip will change when an object moves on the top of sensor and drives the permanent to follow with a specific speed. The principle of velocity measurement was derived and simulation was carried out to determine size of the magnet and size of the whole sensor. Then, a prototype was developed and velocity experiments were executed to evaluate properties of the prototype. The result shows that the prototype was capable of following the velocity curve of a motion platform and measuring the velocity vector of the platform with nonlinear errors of 8.1% and 11.9% along its x-axis and y-axis respectively when the speed was from 1mm/s to 9mm/s.