Chapter 11. An Autonomous Quadcopter

You've now built your quadcopter, and you have the basic flight controller configured. But you'd like your quadcopter to be autonomous, that is, fly itself.

In this chapter you'll learn the following things:

• Controlling your quadcopter remotely from a computer using a joystick, through wireless computer signals

• Adding a webcam so that your quadcopter can do basic autonomous flight

• Adding a GPS device to make waypoint flights

  Tip

  Through experience, I've learned that you will need to add some sort of propeller protection, as you'll very likely run into a wall or some other object more than once, and propellers can be expensive. There are some available at both amazon.com and ebay.in.

Controlling quadcopter flight wirelessly

You've assembled your quadcopter and you can now control it via the BeagleBone Black. But there is still a LAN cable connected to your BeagleBone Black, which will make it difficult to fly very far. This section will show you how to get rid of that cable so that you can control your quadcopter without any wires.

One of the easiest ways to do this is to communicate with the BeagleBone Black on your quadcopter via wireless LAN. If you are using this technique, you'll need to configure a wireless access point for your BeagleBone Black quadcopter to connect to. There are several possible choices:

• You can use a wireless router as an access point to communicate between a computer and the BeagleBone Black on your quadcopter. To do this, simply connect a standard wireless router to the computer, and then configure it as a wireless access point using the directions for your specific router.

• You can configure a laptop computer as an access point to communicate...

Adding a game controller to your system

The software introduced in the last chapter is functional, but not very practical. What you will need is a controller that has more immediate control of the different servos. Perhaps the most practical is a game controller that has two joysticks and several additional buttons. This will make flying your quadcopter through the BeagleBone Black much easier.

To add the game controller, you'll need to first find a game controller that can connect to your computer. If you are using Microsoft Windows as the OS on the host computer, pretty much any USB controller that can connect to a PC will work. The same type of controller also works if you are using Linux for the remote computer. In fact, you can use another BeagleBone Black as the remote computer.

Since the joystick will be connected to the remote computer, you'll need to run two programs: one on the remote computer and one on the BeagleBone Black on the quadcopter. You'll also need a way to communicate...

Adding a webcam for autonomous flight

At this point, your quadcopter is controlled by you via a wireless interface. However, you might want to experiment with allowing your quadcopter to control its own flight. Here you'll learn some basic concepts of Proportional-Integrative-Derivative (PID) control to begin exploring this space. There won't be complete or explicit instructions. That would take a book in and of itself. But you can at least get started.

To allow your quadcopter to fly itself, it will need some information about the world around it. One possible way to provide this is to use a webcam and some markers in your flight area. If you followed the instructions in Chapter 1, Preparing the BeagleBone Black, you should have installed all of the software you need in order to add a webcam and view the world around you.

You'll also need to review the concepts from Chapter 4, Vision and Image Processing, for your robotic project. In particular, what you'll want to do is control your quadcopter...

Adding GPS for autonomous flight

Another way to introduce autonomy to your quadcopter is to use the GPS capability you learned in Chapter 7, Using GPS for Navigation, to give direction to your sailboat; to control your quadcopter autonomously. You can use the GPS to plan new waypoints and path planning to fly your quadcopter to specific locations. You can use the altitude from the GPS to control the height of your flight, although this might result in some rough landings as it rarely gives the kind of resolution to bring your quadcopter down softly. I often use a sonar sensor, similar to the one covered in Chapter 3, Adding Sensors to Your Tracked Vehicle, to sense the ground and land the quadcopter softly.

Summary

Well, that's it! You should have lots of different robots now that can do a number of amazing things. Hopefully this is just the beginning; the rest is left to your imagination and budget. Feel free to explore, although you will almost certainly go through a wrecked robot or two. But that is a small price for the kind of experiences you will have!