Thank you for your answers, I hav' not be able to find this information by myself! What a shame! it will bee usefull to finish a project for a friend: he wants to animate 2 pilots (arms and heads) in his plane during exhibition with scenarios developp on a PC and transfer in a microproc. When visitors travell in front of the plane,2 detectors detect from wich side they arrive and the pilots turn the head one after the other to this side and raise their arms! Funny.
Thank you both