Abstract
The purpose of this paper is to present a multichannel ultrasonic range finder which was designed for the navigation system for blind people. A substantial number of consultations with blind people in the Blind People Centre in Krakow have shown that the navigation and obstacle detection with a help of a white stick only, is not sufficient enough to assure a high safety level. Electronic aids which are being designed for blind people should be mobile, comfortable and low-powered. That is why the MOBIAN© (a mobile safety system for the blind) project is being carried out by the authors to create a highly reliable safety navigation system for blind people. It could not only improve blind people quality of life but also their safety, especially when they are walking in unknown areas. As a part of this project, the multichannel ultrasonic range finder was designed, produced and tested. The tests have proven the device is capable of detecting objects from different directions in a range over 4 m. The device interface is easy to manage and can be controlled by almost any microcontroller or FPGA chip. The designed range finder is to be implemented in the electronic assistant project for blind people. Other systems, including the industrial ones, for instance, mobile robots or gates that count people entries, could benefit from this multichannel range finder. Usually, some low-cost ultrasonic range finders use two transducers for each channel (a transmitter and a receiver). The designed device employs only one transducer per channel which minimizes the end-device size and cost and at the same time provides with the main functionality. Novelty of this device is its multichannel design and the emplacement of the ultrasonic transducers, which can be used due to the application of the multichannel analog multiplexer. Thus, it is possible to detect obstacles, even the inclined ones, with higher reliability and increase the safety of blind people while walking. Also, this design and the transducers’ placement allow to detect obstacles much quicker, when the blind user suddenly turns.
A Novel Hybrid Fusion Algorithm for Low-Cost GPS/INS Integrated Navigation System During GPS Outages