An alternative method of distance measurement walked by the blind

Summary : The blind person cannot often take advantage of skilled learned, such as taking care of day to day needs without the capacity to successfully travel. Therefore, there is a need for navigation aids to help the blind to be independant from the help of a normal sighted person, and to be able to walk journeys which have not previously been rehearsed. As part of this, there is a particular need for a device to enable the distance travelled by a blind walker to be determined continiously as the journey progresses. In this paper, the proposed method of measuring distance is to use the acceleration of a moving body which in this case is the blind person. The technique well known in air-craft navigation systems of using an accelerometer and double integrating its output gives a measurement of distance travelled. This method suffers from drift of the integrators and offset of the accelerometer. An innovation in the present paper is a suggested way to overcome this problem by the use of a footswitch when the blind walks.