Distance Sensor

Overview

Bats use sound waves for navigation. By emitting a high frequency sound, then by listening to the sounds bounced back, they can determine if something is in their path. Robots can use a similar method by emitting a chirp at a frequency above human hearing. Then a precise measurement is made of the time it takes for the sound to bounce back. With knowledge of the speed of sound and the transit time, the distance can be calculated.

Application

The quickest way to demonstrate an ultrasonic Distance Sensor is to snap one on the front of a robot and plug it into the VEX IQ Robot Brain. The programs built-in to the Robot Brain will automatically detect the Distance Sensor and start using the information. The Driver Control program will monitor the range in front of the robot. As the driver drives the robot towards an object, the robot will automatically slow down to avoid collision with the object.

Use

The best use for a Distance Sensor is to help with navigation. Avoiding hitting objects is easy if you can "see" how much room you have in front of you. Distance Sensors also help with navigating mazes without having to hit a wall to know it's there. Your location can also be calculated by measuring the distance to the walls around you.

Microcontroller

The VEX IQ Distance Sensor uses a Texas Instruments MSP430 microcontroller running at 16 MHz to create pulses and measure sound reflection time. Two features used in commercial radar systems, logarithmic amplifiers and automatic gain control, improve accuracy to provide a wide measurement range. Features that automatically alert the Brain if a specified distance is measure makes writing software easy. All this technology works together to make a smart distance sensor that is simple, flexible, and powerful.