Mechatronic hand prosthesis for child

The design of a distal extremity prosthesis (right hand) based on the anthropometric measures of a 10-year old child is presented. Each finger is disposed in two sections, a fusion of the middle and distal phalanx, and a proximal phalanx articulated to the hand palm. The angles of the movement for the extension and flexion of all fingers, except the thumb, are controlled by a link located sideways. The drive system, that generates three degrees of freedom to execute the cylindrical grasp's functions, the precision grasp, hook prehension and the extended index finger, is based on three linear actuators located on the palm, which have a reference potentiometer that provides its position, such indication is used by the microcontroller via the analogic input signal. To validate the design, a stresses and displacements analysis, and the determination of the safety factor that offers the device for the selected materials is carried out, using a computer program based on the Finite Element Method. The results obtained show a light prosthetic device that weights 150 grams, and can operate safely allowing four grip functions with the normal angles of the hand.