This paper addresses the question of embedded human motion sensing, in the framework of interaction with an artificial controller, either for activating a robot or for stimulating impaired human links. After a short presentation of the sensing problem and of the related measurement technologies, we describe the two main applications we have considered. The first one is the early detection of the paraplegic's intention in a Sit-to-Stand Transfer problem; here the actuation consists of the electro-stimulation of the knee extensors of the patient. The second is the estimation in real time of a variable allowing to synchronize the motion on a robot leg or of the impaired leg of a stroke patient on a human stationary walking gait. A few perspectives are drawn in the conclusion.