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.