Enhanced Perception for Visually Impaired People

Visually impaired or blind people have a reduced ability to perceive their environment. The accessible environment is drastically constrained by the length of canes. Numerous approaches e.g. ultrasound enhanced canes did not solve the problem. Most of them use the auditory system for information transfer, which is not appreciated by the blind because acoustics are already involved in the spatial orientation. It is proposed to use fast 3D object recognition (3D camera) 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 two different coding schemes to communicate the state of a real time game to subjects. Goal of the game is obstacle avoidance. An elastic belt was employed that may accommodate up to 15 vibration motors as used in mobile phones. In the experiments up to 8 motors were 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. This is compared to a direct decision scheme, that is based on an intelligent situation analysis. Non handicapped students were involved as study objects to determine real time performance and learning speed. In a first step the subjects were facing a simple computer game. Collisions of a player with other objects had to be avoided. The performance of the individuals was determined concerning velocity and the number of objects. In a second trial the subjects are blinded and information, in this case -recommended actions - are directly transmitted to the subjects via the vibration motors. Significantly better results could be achieved with prior optimized action proposals, though they can be further optimized- . No special training was required and all subjects were able to perform additional tasks while avoiding obstacles.