USB Mouse for Tetraplejic People based on Head Tracking

Abstract

This paper presents the design and implementation of a USB mouse for disabled people, with special attention for those who are tetraplejic. The theory behind this design supposes the user has his head as the only resource for moving and clicking the mouse cursor on the screen. The implementation was made by means of a microcontroller unit which has an USB (Universal Serial Bus) interface and an analog-digital converter (ADC). Head movements and screen position were registered by means of accelerometer technology. Designed and implemented algorithms on the microcontroller firmware process all the accelerometer information for controlling the mouse cursor on the screen. This design is easy to use: a sensor is put on user’s glasses, and another one is put on computer’s screen. Connection to the computer is made by means of an USB cable, without installing additional software, since this design was developed using the HID (Human Interface Devices) class that comes with some platforms as Windows R or Linux. The mouse was tested under three operating systems on different computers, namely, Windows R XP (32 bit), Windows R 7 (64 bit) and Ubuntu Linux (32 bit). Mouse’s basic functions was tested by seven people without previous training. This test showed that a better tuning for the thresholds on our proposed algorithms is desirable, and it could be made as a future work by taking a representative sample of our target population. We got 6 %, 3% and 1% in mistakes on right-click, and up and down cursor’s movements respectively. On the other hand, we got 22 %, 12% and 10% in mistakes on left-click, and left and right cursor’s movements respectively.

Keywords

• ratón para discapacitados
• tetraplejia
• dispositivo de entrada USB.