Ultrasonic detection devices can be classified into two types: an audio feedback and a tactile feedback. Examples
of ultrasonic audio feedback devices are Echolocation (9), Navbelt (10), and the project from Florida International
University (FIU) (11). The disadvantage of these audio feedback devices is that the visually impaired users
cannot access auditory sense in urban scenarios. Regarding the tactile feedback approach, Guide cane (12)
has a limited detection on the ground and sideways obstacles only. As for the disadvantages of CyARM (13), the user
always needs to hold it to scan the environment, and the device is too heavy. As for the Tactile Handle (14, 15), this
device uses four ultrasonic sensors to detect obstacles toward the front, left, right, and bottom of the user’s
hand. The 44 tactile arrays represent different obstacle positions. To ensure its effectiveness, the results show that
excessive user training is necessary.