A portable and low-cost assistive computer input device for quadriplegics

Abstract

A useful assistive computer input device owning keyboard and mouse functions designed to assist quadriplegics is proposed in this paper. Users can operate the computer through a nipple switch with Morse code encoding. Because of the difficulty with keeping a stable typing speed and ratio of Morse code, the fuzzy algorithm is applied to solve this problem, as it recognizes the unstable Morse code. The proposed device is mainly constructed with a microcontroller, which implements several tasks: 1) Universal Serial Bus (USB) task; 2) Mouse task; 3) Keyboard task; 4) Morse code task. Since the proposed device only needs a few common components, we can lower the cost of the proposed device and design it to reach a small size (50 × 25 × 10 mm) in accordance with actual requirements. In our experiment, the three subjects, quadriplegics, who had been trained in three days could smoothly operate the functions of the mouse and could type at least 15 English letters per minute after a course of two weeks training. With the increase of training time, the fastest typing speed one of the subjects could achieve was 63 English letters per minute. This device is one of the most convenient assistive computer input device for quadriplegics.