A Tilt Mouse With Acceleration Sensor

Objective: People with hand disability or suffering from spinal cord injury cannot use a mouse with their hand,since motor function is impaired by disease.To provide these people access to computer,a tilt mouse using an acceleration sensor had been designed.With the tilt mouse,the user can move cursor around the computer screen in a hands-free manner.Content: The major contents in this paper include:realization of cursor moving,realization of mouse click,realization of wireless transmission and realization of filter algorithm.A control signal was selected and translated into cursor displacement to control the movement of cursor.A circuit was built to realize mouse click in a hand-free manner and a wireless transmission protocol was selected to realize the wireless transmission of mouse data.The noise resulted from the internal capacitance,AD and conditioning circuit in the acceleration sensor may occur when measuring the motion of head.In order to eliminate the influence of noise on the mouse system,a filter algorithm was added to improve the stability of the system.Results: The angle of head tilt was selected as the control signal to control the movement of cursor.An acceleration sensor ADXL345 was used to measure the acceleration of head movement.Then the angle of head tilt was calculated from the acceleration data and was translated to the movement of cursor with microcontroller MSP430F5529.Two air-blowing switches using relay and voice-activated module were built to realize the mouse click.Transmitting and receiving circuit was built with transceiver chip n RF2401 to realize the wireless transmission of mouse data.Besides,an improved Kalman filtering algorithm was used to process the acceleration data acquired and the noise can be decreased obviously.In the performance test,the optical mouse can open and close a file in 3.66 s on average,while the tilt mouse can complete that in 11.76 s.Conclusion: The angle of head tilt was selected as the control signal.The cursor on the screen could be moved effectively by translating the angle to the movement of cursor.And mouse click could be realized by blowing in to air-blowing switches.The tilt mouse can provides computer access to persons with motor impairment and help them move cursor efficiently in a hand-free manner,but it is still no match for the optical mouse.