Ratón USB para Personas Tetrapléjicas Controlado con el Movimiento de la Cabeza
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Universidad Distrital Francisco José de Caldas
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Este articulo presenta los resultados del diseño e implementación de un ratón USB (Universal Serial Bus) totalmente hardware destinado a personas que tienen algún tipo de discapacidad en alguno de sus cuatro miembros, con especial utilidad para aquellos que sufren de tetraplejia. La teoría detrás del diseño supone que el usuario puede mover el cursor en la pantalla del computador y hacer clics izquierdo y derecho, utilizando solamente la cabeza. La implementación se realizócon un microcontrolador que dispone de interfaz USB y conversor analógicodigital (ADC). El registro del movimiento de la cabeza del usuario y la posición de la pantalla se hizo mediante tecnología de acelerómetros de tres ejes. Los algoritmos diseñados e implementados en el firmware del microcontrolador realizan todo el trabajo necesario para procesar la información de los acelerómetros y así controlar el cursor en pantalla.Se observóque el diseño es fácil de usar: el sensor del usuario se pone sobre sus gafas y el sensor de la pantalla se pone sobre ésta con una pinza plástica. La conexión al computador no requiere instalar software adicional, dado que es compatible con la clase HID (Human Interface Devices) que viene por defecto en varias plataformas como Windows ® y Linux. El ratón fue probado en tres sistemas operativos sobre computadores diferentes, a saber, Windows ® XP (32 bit), Windows ® 7 (64 bit) y Ubuntu Linux (32 bit). Se realizóuna prueba de las funciones básicas del ratón sobre siete personas sin entrenamiento previo. Esta prueba mostróla necesidad de una mejor sintonización de los umbrales en los algoritmos propuestos, que puede realizarse como trabajo futuro tomando una muestra representativa de la población objetivo. Se alcanzaron 6%, 3% y 1% de desaciertos en la ejecución del clic derecho, y movimientos arriba y abajo del cursor respectivamente. Por el contrario, se alcanzaron 22%, 12% y 10% de desaciertos en la ejecución del clic izquierdo, y movimientos izquierda y derecha respectivamente.
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 designsupposes the user has his head as the only resource for moving and clicking the mousecursor on the screen. The implementation was made by means of a microcontrollerunit which has an USB (Universal Serial Bus) interface and an analog-digital converter(ADC). Head movements and screen position were registered by means of accelerometertechnology. Designed and implemented algorithms on the microcontroller firmwareprocess 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 puton 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 theHID (Human Interface Devices) class that comes with some platforms as Windows Ror 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 testshowed 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’smovements respectively. On the other hand, we got 22 %, 12% and 10% in mistakes onleft-click, and left and right cursor’s movements respectively.
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 designsupposes the user has his head as the only resource for moving and clicking the mousecursor on the screen. The implementation was made by means of a microcontrollerunit which has an USB (Universal Serial Bus) interface and an analog-digital converter(ADC). Head movements and screen position were registered by means of accelerometertechnology. Designed and implemented algorithms on the microcontroller firmwareprocess 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 puton 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 theHID (Human Interface Devices) class that comes with some platforms as Windows Ror 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 testshowed 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’smovements respectively. On the other hand, we got 22 %, 12% and 10% in mistakes onleft-click, and left and right cursor’s movements respectively.
Palabras clave
Hands-free mouse, Tetraplegia, USB input device, ratón para discapacitados, tetraplejia, dispositivo de entrada USB.