Sensors

Does anyone know if there's a sensor that can be used to track a person as they walk across a area so an object can be followed for a distance of around 10 m it's for my sons project he wants a robot head to be able to follow him around up down left right if possible just left and right would do though thanks

A video camera, connected to a PC with tracking software would do it.

One of the ArduCam models could be used.