Components For Map Building Ultrasonic Range Sensor,...

Overall System A- Hardware Subsystem This system uses three components for map building Ultrasonic range sensor, Stepper motor driver and Serial communication system. The microcontroller here is a central processing unit to coordinate the previous three. Ultrasonic Range Sensor SRF05: The sensor operates in Mode 1 which uses a separate trigger and echo pins. These pins are connected to the PORT A of the microcontroller and are responsible for triggering and measuring the time of flight of the echo. The trigger pulse has a minimum duration of 10Â µS, for stable operation and an internal ultrasound burst of 8 cycles at 40 kHz is sent. At the end of this process the state is preserved until an echo signal is received. At the reception of an echo, the echo pin is cleared by the module and the microcontroller detects it and stops the echo timer. Stepper Motor Driver This motor is driven using the control signals from PORT D of the microcontroller. These signals are fed to a Darlington array which in turn drives the motor at 12V. Utilization of the Darlington mechanism prevents drawing large currents from the microcontroller at high loads. The resolution of the stepper motor is increased to 1.50 by utilizing a gear wheel with a gear reduction of 1:5. Readings are taken at each step location by momentarily stopping the shaft and four such readings are averaged to obtain a single reading for each 60. This helps the system to suppress any transient errors which