ROBOTICS BASED OBSTACLE AVOIDANCE SYSTEM



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INTRODUCTION:

Guide cane is a Novel navigation aids designed to help visually impaired users navigate quickly and safely among densely cluttered obstacles. It is a mobile robotics based device which uses obstacle avoidance technology to determine a safe path for travel and to guide the user along that path.


FUNCTIONAL COMPONENTS:
A servo motor, operating under the control of the built in computer, can steer the wheels left and right relative to the cane. Both wheels are equipped with encoders to determine their relative motion. For obstacle detection, the guide cane is equipped with 10 ultrasonic sensors. To specify a desired direction of motion, the user operates a mini joystick located at the handle. Based on the user input and the sensor data form its sonar’s and encoders, the computer decides where to head next and turn the wheels accordingly.


INFORMATION TRANSFER:

The unique feature of the Guide cane information transfer through direct physical force. This process is completely intuitive so that everybody can use the system right way without learning how to interpret artificial signals. Yielding to external force is a reflexive process that does not require a conscious effort. The Guide cane can apply a substantial amount of physical force on the user.



MECHANICAL HARDWARE:

The Guide cane consists of housing, a wheelbase, and a handle. The housing contains and protects most of the electronic components. The current prototype is equipped with ten Polaroid ultrasonic sensors that are located around the housing. Eight of the sonar’s are located in the front in a semicircular fashion with an angular spacing of 15º, thereby “covering” a 120º sector ahead of the guide cane.


ELECTRONIC HARDWARE:

The brain of the Guide cane is a 486/33-MHz, PC-compatible, single board computer. A custom,-built microcontroller interface board (MCIB) interfaces between the PC and the sensors (Sonar’s, Encoders and potentiometer) and actuators (main servo and brakes) via a standard parallel port. The MCIB performs many time-critical tasks, such as firing the sonar’s at specific times, constantly checking the sonar’s for an echo generating the pulse width modulation (PWM) signals for the servos, and decoding the encoder outputs.