# Concept, Design, Initial Tests and Prototype of Customized Upper Limb Prosthesis
###### Abstract  
This paper presents aspects of the concept and design of prostheses for the upper limb. The objective of this research is that of prototyping a customized prosthesis, with EMG signals that initiate the motion. The prosthesis' fingers' motions (as well as that of its hand and forearm parts) are driven by micro-motors, and assisted by the individualized command and control system. The software and hardware tandem concept of this mechatronic system enables complex motion (in the horizontal and vertical plane) with accurate trajectory and different set rules (gripping pressure, object temperature, acceleration towards the object). One important idea is regarding customization via reverse engineering techniques. Due to this, the dimensions and appearance (geometric characteristics) of the prosthesis would look like the human hand itself. The trajectories and motions of the fingers, thumbs, and joints have been studied by kinematic analysis with the matrix-vector method aided by Matlab. The concept and design of the mechanical parts allow for complex finger motion--rotational motion in two planes. The command and control system is embedded, and data received from the sensors are processed by a micro-controller for managing micro-motor control. Preliminary testing of the sensors and micro-motors on a small platform, Arduino, was performed. Prototyping of the mechanical components has been a challenge because of the high accuracy needed for the geometric precision of the parts. Several techniques of rapid prototyping were considered, but only DLP (digital light processing) proved to be the right one. prostshesis; reverse engineering; 3D prototyping; embedded command and control system; sensors +
Footnote †: 27 March 2021  
Many of these people \"suffer from frustration and difficulty during the rehabilitation process and experience paresthesia due to the loss of delicate movement by the hands, complicated tactile senses of the upper extremities, and proprioceptive sensory functions [3]\" and all of these people require assistive technologies such as prostheses, wheelchairs, etc. Considering the crucial functions of hands, the life of people who are missing hands is complicated, and, for this reason, it is very difficult to adapt to situations in which something that used to be done naturally is now done within limits imposed by this disability. Upper limb prostheses (ULP) are generally classified into two categories based on their functionality: passive prostheses and active prostheses [4], cited by [5]. A good solution for artificial hands is myoelectric prostheses, which are currently being developed. With these types of prostheses, the myoelectric signals of muscle contractions are ultimately transformed into functions desired by the users through the use of surface electrodes [3]. It is a'myoelectric control system' for controlling the myoelectric prosthesis [6], cited by [3]. However, the design, the control structure, and the manufacturing process are difficult, and moreover, the cost is a very important element to consider in all of these phases [3; 5]. An adaptable hand with flexibility, dexterity, and load carrying capacity analogous to the human hand seems to be the ideal objective for prosthetic application [7]. Prosthetics research has contributed to the development of very complicated hand prostheses but their structures, with programmable control systems, are not always user-friendly. This makes them very difficult in operation, and the people at whom they are aimed do not use them in the usual way [7; 8; 9; 10]. Thus, it is necessary to develop intelligent prostheses that can be easily adapted to the requirements of each individual they are intended for. For the development of such products, researchers must consider the following basic systems: mechanical, actuators and motors, sensors, and command and control [10].