3. Development of navigation system for the visually impaired

In order to develop the navigation system, which will benefit the visually impaired people, a total navigation system that includes a path planning system, RFID detection system, and obstacle detection system is needed. However, in this chapter, the developed navigation system is only focused on the tactile pavement detection system using the image recognition method. Moreover, implementation of digital compass is used to guide visually impaired people when traveling [35]. Figure 1 illustrates the system architecture by using ZigBee wireless networks for the communication between the server/laptop and the developed navigation device.

We developed the ZigBee network in order to connect and monitor the developed navigation device when the experiment is conducted. The ZigBee network acts as the center of data transferring between the navigation device and the server/laptop. The movement of user will be shown to the map processing system on the server/laptop respectively. Hence, the user's current position to the desired position will be displayed on the map based on a generated route. The map system then identifies the address of the target. Concurrently, the RFID reader/ writer module will read the RFID tags on the tactile paving or floor. The data of the RFID tags of the current position and the address is sent for map processing.

Vision-Based Tactile Paving Detection Method in Navigation Systems for Visually Impaired Persons 33 http://dx.doi.org/10.5772/intechopen.79886

Figure 1. System architecture of developed navigation system including server/laptop.

Next, voice guidance commands will also be given based on the route, which has been generated, to the user through an earphone. The earphone connection is based on a Bluetooth connection. The server/laptop will send the voice guidance and user position will also be updated at the same time. Path recalculation will also be done again and voice guidance is produced if the user takes the wrong path from the recommended path. The benefit of the system is when the user needs to take a corner turning, the digital compass will compare the angle and ensure the user takes the corner effectively without hitting the nearby obstacles. The server receives data from ZigBee network and suggests mounting at fixed locations inside the buildings. The server must be updated and the information of the destinations and objects needs to be stored inside the database with respect to the map system.

In order to optimize the functionality of the developed navigation device for guiding the visually impaired people in the correct direction throughout the travel path, the experimental setup to evaluate the accuracy of the digital compass is set. The orientation or direction is attained by using a digital compass mounted on the developed electronic cane. The digital compass is connected to the Arduino microcontroller to obtain the analog signal and convert it back to the digital signal by using the onboard analog-digital converter (ADC). The digital signal will be displayed on the serial monitor of the Arduino microcontroller and the digital compass can be tuned accurately. The digital compass is fixed at the certain point where the RFID tag has been mounted to ensure the digital compass is always pointing to the north.
