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3. Avoid obstacles, create strategies



In this video the Arduino team will explore how to use different technologies to detect obstacles in the way of the Arduino Robot. The three technologies being tested are: ultrasonic range finders, infrared range finders and a trick using ultrabright white LEDs and LDR sensors.

The video starts with a brief explanation on ultrasound and how it provides information about the objects and obstacles in front of the sensor. Xun and David attach one of those sensors to the robot and execute an example called “Avoid Obstacle” that was specially designed for the Maxbotix EZ-10 ultrasonic range finder.

The second example shows the use of two Sharp infrared sensors. There are several types of sensors from this brand providing different types of data. In this case, we'll see how to use one that gives an analog voltage mapped to the distance to objects.

In a sense ultrasound and infrared operate in the same way: a signal is sent, it bounces on objects and the received echo is used to estimate the distance. With ultrasound, the speed of sound and the time difference between the sent signal and the received one is used, while infrared is more direct as it gives a stronger or weaker reflection depending on how far the signal travels. The estimation of the distance is done via software. You will see a simple example of this when changing from ultrasound to infrared sensors.

In the infrared example, David and Xun attach two sensors to the TinkerKit connectors on the robot. In the case of the ultrasonic sensor the robot can only see whether there is something in front; however with the infrared sensor, the robot can decide which side is closer to the obstacle and subsequently decide which direction to turn to avoid it.

The final example shows how simple it can be to build your own reflective sensors using a very strong source of light and an LDR sensor. In this case standard TinkerKit components are used: an ultrabright LED module and an LDR module. This example works in the same way as for the infrared. In this case, the infrared is invisible to the eye, while the light emitted by the ultrabright LED is not.

The following video will show how to get your robot to follow lines using the IR-array sensor at the bottom of the motor board. Make sure to subscribe here.

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