Haptic Display of Depth Images in an Electronic Travel Aid for the Blind: Technical Indoor Trials

This paper reports on an assistive system for the visually impaired that presents the environment through haptic stimulation. This wearable system consists of a processing unit attached to the user's chest and a haptic belt placed to the user’s abdomen. The custom-made belt consists of 20 vibration actuators arranged in a 4 × 5 matrix. The depth images captured by the camera are processed to identify the orientation of the ground plane and the location of obstacles. The system's detection range is limited to 2.5 m within a user-defined corridor 0.8−1.5 m wide. The segmented obstacles in the depth images are projected onto the so-called occupancy grid, which is a top view of the scene. Each grid cell corresponds to a haptic actuator that is activated when the cell is occupied by an obstacle. The system is capable of real-time haptic representation of the environment. We present successful indoor technical trials of the system, demonstrating its validity as a potentially useful travel aid for the visually impaired.