The ultrasonic waves are sound waves of a certain frequency range

System work, the microcontroller P1 port output control signal pro clutch drive chip 74HC245 and photoelectric input motor driver chip L298N to control motor movements. When the governor of the need, simply by changing the duty cycle of the PWM wave (in the design generated by the microcontroller ports P1.3 and P1.6) can, in theory, can achieve 256 governor.The ultrasonic waves are sound waves of a certain frequency range, the frequency of 40kHz ultrasonic signal propagation efficiency in air. This selection of the center frequency of 40kHz, ranging the ordinary ultrasonic sensor range less than 5m.

The sensor transmitting probe and the receiving probe is mounted in front of the robot is, The minimum distance of the distance of obstacles in the process set in the main program the robot to walk, when the measured distance is less than the minimum distance, the controller to the drive system instruction issued obstacle avoidance, obstacle avoidance. This design software delay to remove crosstalk misoperation issued a period of time, i.e. in the transmitting wave, and then open to external interrupts, to avoid transmitting wave directly by the receiver without reflection caused false interrupts.

when the system is operating, by the assembler by the P3.7 port the accurate 40kHz-emitting pulse, Transmitting wave encounters an obstacle reflected back by the receiver, converted into an electric signal pulse, notebook battery to the signal amplification, filtering, comparison, and after processing such as shaping into the microcontroller external interrupt port INT1 external interrupt is triggered to enter interrupt handler, and get to the receipt of the reflected wave interval ie ranging time issued from the launch waves, which can be calculated based on ultrasonic ranging principle obstacle distance.
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