3.6: Front Range Sensor

Step 1

Getting Started

Make sure that your drone is connected with Blockly before starting the lesson! If you are unsure of how to connect, go back to lesson 1.1 to review!

Step 2

Introduction to the front range sensor

CoDrone EDU is equipped with a front range sensor that can detect physical objects in front of it within 1.5 meters (150 centimeters). It is the same sensor that you used in the previous lesson to detect the distance to the surface below. It emits infrared light and measures the time it takes to reflect back into the receiver.

You can access the front range sensor data with the get_range() block in the Sensors menu. Start by printing the front range sensor value. Go to the sensors menu and drag the get_range() function into your workspace.

frontrange-getrange-senior-cde-blockly-cm

To see the values, attach a print block. Then, add a sleep(0.5) seconds block from the Timing category. Run all of this in a loop to repeat 20 times.

While running the program, slowly move your hand toward and away from the front range sensor.

Try changing the units by selecting millimeters or inches from the dropdown menu and repeating the experiment. As a bonus, grab a ruler or meter stick to measure the accuracy of the sensor.

Step 3

Safe takeoff

Pilots often do a series of pre-flight checks to make sure that everything is working on their aircraft before attempting to fly. One thing to consider checking is making sure that the take off area is clear. Since CoDrone EDU has a front range sensor, you can automate this process! For our next program, the drone will only take off if there is not an object within 30cm (about 12 inches) in front of the drone.

Start by making a variable called `distance`. This variable will store the minimum distance in centimeters that should be clear in front of the drone. Since you only want the drone to take off if the there is no object in front within 30 centimeters, set the variable to 30.

Before taking off, use an if statement to check if the area is clear by comparing the data from the front range sensor (in centimeters!) to the variable. Write a warning message if the sensor is detecting an object less than 30 centimeters away.

The if statement below will only return true if there is an object within 30 centimeters from the front of the drone. If that is not true program an “else” statement to take off and then land. Make another print statement to state that the drone has been cleared for takeoff!

Step 4

Avoid an obstacle during flight

Now that preflight checks are complete, add in some flight movements! If the area is clear for takeoff. CoDrone EDU will take off and fly forward until it detects another obstacle.

You are going to add code to the else statement. Since you don’t know how long it will take for our drone to find an obstacle, include an infinite while loop. Add a while loop after takeoff.

While the sensor is reading any value greater than 30 centimeters, CoDrone EDU should keep flying. You can copy and paste the same conditional from earlier, but don’t forget to change the less/greater than sign the opposite way!

cdeb-blockly-frontrange1-while-loop-conditional

Add in the flight movement for CoDrone EDU to fly forward while there is no obstacle ahead. Since we are relying on sensor information to detect an obstacle, fly forward with precaution at a lower speed. Then, add a move() block without the seconds delay. If you add a delay it will slow down the program and you might crash into an obstacle before the sensor was able to detect it in time.

cdeb-blockly-frontrange1-while-loop-conditional-with-move

Finally, outside of the loop, add a print statement and land. Here is the final code:

cdeb-blockly-frontrange1-while-loop-conditional-move-final

Step 5

Challenges

Challenge: Drone Basketball

For this challenge, make your own basketball hoop using a wall and hula hoop or other materials. Your goal is to have CoDrone EDU go through the hoop after detecting the ‘backboard,’ just like a basketball would! In order to complete the challenge, you must do the following:

Create your own basketball hoop for CoDrone EDU to fly through
Your program must have the CoDrone EDU fly towards the hoop, detect the wall/backboard, and fly through the hoop before landing

Challenge: Homing in

For this challenge, you will be programming your CoDrone EDU to fly as close to the wall as possible! Using the front range sensor, try and write a program that will stop the CoDrone once it reaches a certain distance from the wall; that distance will depend on where you are flying your CoDrone EDU, so make sure to test out different values!

Step 6

Lesson Complete

In this lesson, you learned how to use the CoDrone EDU’s front range sensor to detect how far an object is in front of the CoDrone EDU. It has many useful applications like building autonomous navigation programs and safety features.

This lesson works with:

Grade level:

Approx. time required: