Ultrasonic Navigation

Here is something that could really replace the walking stick. A team from Cornell University developed a navigation system using an ultrasonic sensor that can help you move around without using your sight. The interaction between the obstacle detector and the operator is done using  vibrator motors.

Looking at the block diagram we can distinguish five main areas or modules if you like. We have the haptic interface with the vibrator motors and the ULN2803 IC that drives them, we have the LV-MaxSonar-EZ1 ultrasonic range finder with the bipolar stepper motor and the full bridge driver L298HN, we have the RF transmitter using RCT-433 that sends data wirelessly to a computer for further analysis, we have the ATmega644 microcontroller, the system’s brain and we have the power supply batteries.

The ultrasonic sensor scans the area for obstacle and if it finds any gives out the distance to it. The scanning is done with the help of the stepper motor who rotates the sensor from left to right and back again, covering 270 degrees. Each step rotates the motor 7.5 degrees so it needs 36 steps for a complete sweep. This gives the direction of the obstacle.

Information about the distance to the obstacle and direction is then sent to the ATmega644. After the microcontroller processes the data, it controls the vibrator motors. These motors are spaced 45 degrees apart around the head. The intensity of their vibration varies depending on how close the obstacle is.

The microcontroller also sends out data on RF for further processing on a PC. This data is composed of range information at different angles, stepper motor angle and direction of rotation, vibrator motor status. This data is sent every 45 degrees of the stepper’s rotation.

This is a very documented project with lots of pictures, all schematics and source codes, all the build experience, what things you should be careful about, the problems that were encountered, it’s all there.

Ultrasonic Navigation: [Link][Via]