AERBUS: Enhanced perception of the environment for visually impaired people

Many aids have been proposed for the visually impaired or the blind. The regular cane is widely accepted but has known limitations such as a small perceptual range constraint by its short length. Numerous approaches such as ultrasound enhanced canes have been developed with limited success, the main reason being the information transfer over the auditory system, one of the most important spatial senses. It is proposed to use fast 3D object recognition in conjunction with a priority based information reduction as used in autonomous mobile robotics to generate a virtual velocity map of objects in the surrounding. This information shall be transferred to the cognitive system of the blind via the stimulation of skin receptors. Here we report on the evaluation of a special belt to communicate object locations and velocities to subjects. An elastic belt was designed to integrate up to 15 vibration motors as used in mobile phones. Currently up to 8 motors can be controlled simultaneously via a parallel port of a PC. The direction towards an object is coded by the location of the motor in the belt (local coding). Velocity information is transferred to the person by a pulse coding scheme. Non-handicapped students were involved as study objects to determine perception thresholds and accuracy of perception. In a first step the subjects were facing a forced choice test to optimize the individual perception thresholds. In a second trial position and strength of signal coding were evaluated. Position information was correctly identified by the subjects within 15 degrees. Pulse frequency in the range of 0.1Hz to 2 Hz could be perceived strongly and were distinguishable. The strength of the vibration and its location could be used for spatial orientation. This "vibration information" can be used by the subject to make assumptions about approaching objects.