PEPA:
Programmable Electronic prosthetic Appendage
Abstract — The continuity in advancement of 3-D printing techniques and technology has created a new and vast section in the mechanical industry that makes it possible for the average person to be able to utilize these technologies and create any product physically at the fraction of the cost as compared to ordering and buying it from suitable vendor. Our project will employ a 3-D printer that will be used to print all physical aspects of the arm itself; the arm will be printed from the elbow all the way to the finger tips with a special design that will allow the incorporation of electric and electronic devices and circuits. With accordance to that, this project will apply most of the knowledge gained in several courses to create a programmable, technological, and sustainable prosthetic appendage.
Project Description:
The project’s goal is to implement several electronic components and devices to produce a fully functional prosthetic appendage. In this paper, various electronic devices and elements will be integrated to produce the complete and final design.
One of our main aims is to deliver a completely functioning prosthetic appendage that can be used by any mature person to perform basic arm functions such as hand gestures and movement, as well as grabbing a multitude range of objects of different sizes. This project’s objective is to implement various sensors while being monitored by a microcontroller simultaneously to produce a bionic arm that allows any user to be able to use it without any difficulty. The last objective is to incorporate several electronic devices, parts, and elements to produce a product that can be economically attainable by middle to lower class citizens.
The specifications have been set out by the authors were the arm itself will be 3-D printed to provide a custom made physical look as well as an affordable method of production of the arm, which will act as a host to several sensors, including a microcontroller and an LED screen that will be implemented in the design. A microcontroller will be first implemented into the arm itself to act as the ‘brain’ of this appendage.
The microcontroller will analyze user data, and then perform the necessary tasks needed to control most of the functions. The flexion and extension of all the five fingers will be performed using five motors that will rotate clockwise or counter-clockwise according to which motion is required. Other sensors, such as a heat sensor, may be integrated as well to add to the technological aspects of the arm itself.
An LED/LCD screen will be added to provide an easy-to-use user interface for any individual. Some parts, such as the servo motors, will need more power than the microcontroller can provide, and as such, proper circuitry has been designed and added to provide sufficient power to all the elements that require it. The integration of all these features will result in a fully functioning arm that will perform basic hand and arm motor actions in addition to gestures.
After some research, it became clear that designing a prosthetic appendage would have been a time consuming task and as it is mainly a mechanical aspect of the project, we opted out of designing it and instead, looked for other sources to obtain STL files of an arm that was either an open source or the owners provided permission for using it.
After obtaining the files, the arm itself needs to be printed, and buying a 3-D printer or using private owned printers has been proved to be costly as purchasing a printer requires a good monetary investment, while private companies that 3-D print object for consumers charge each project by the 3 dimensions (x, y, and z) and the total weight of the object as well as the total amount of time it took for the project to be completed. The choice of servo motors was decided as it would perform the necessary task, and the affordability of the motor itself played a part into choosing it. Research into durable lines was concluded by having to either decide between using fishing lines or guitar strings as a mean to connect the servo motors to the fingers individually.
Building the Arm:
The Arm itself is designed by INMOOV. An open-source life sized 3-D printed robot, and we are just using their arm designs. We sent the STL files to ASME (American Society of Mechanical Engineers) at UCF, and had them print the arm at the beginning of the spring 2016 semester. Below are a selection of pictures of printed parts of the
arm.
Figure 1: The components that built the hand of the arm
Figure 2: The 3D printed components used for the wrist and forarm
Figure 3: The upper pat of the form arm and the parts for holding the servos.