How RC Cars Work
Outline:
What does "RC" stand for?
RC stands for radio controlled. As in "Radio Controlled Car!" When you hear the term "radio" you probably think of the radio in your car. The one that plays music. This is the same concept that our RC Car uses for controlling forward/backward and left/right movement. It "speaks" using radio waves. The very same type of radio waves that produce music on your car stereo.
What types of radio communication occur?
First, let's understand that we have two pieces that communicate. A transmitting piece, and a recieving piece. The trasmitter piece is called the "radio controller" and looks like [this - place img here]. The reciever piece is called the "radio reciever" and looks like [this - place img here - have two pictures showing the location in the car.] When the forward lever on the controller is pressed, it makes a connection between two wires in the controller that tells it to transmit a "go forward" signal to the reciever in the car. Conversly, when the arm is rocked backward it transmits [put a flash file in here demonstrating this concept] a "go backward" signal. This signal is picked up by the "radio reciever" and the car goes backwards. Sweet! Our car is now moving! Let's learn a bit more about the "radio controller" and "radio reciever."
The radio controller / radio reciever
The radio controller is made up of a circuit board, a quartz crystal, wires, and a battery to power it all. Details on how to construct this are beyond the scope of this article. The circuit board is used to hold all the pieces together, the foundation of the device, if you will. Stay with me here! The wires connect the different logic circuits together. When the forward/backward arm is pressed [flash demo?] it creates a connection between two wires. These wires are connected to the crystal which then vibrates at a certain frequency, producing "radio waves!" Neat, huh? When the forward/backward arm is reversed, a different connection is created with the wires which tells the crystal to vibrate in a slightly different way - different enough to be discernable (too advanced language?) enough from the first transmission. The crystal is the key. The cornerstone. How the crystal vibrates determines the "message" the controller transmits.
The radio reciever is pretty dumb, actually. It doesn't do anything except listen. Listen all day long to the air. Its job only gets exciting when it hears something. And then magic occurs! The radio reciever is (note: what kind of material comprises the reciever??) made up of.... When something is vibrating at the right frequency in the air, one that the reciever can hear, the radio reciever activates its circuits. Depending on what the reciever hears, it activates circuit 1, or perhaps circuit 2, or perhaps circuit 3, or perhaps well... you get the picture. What the reciever does is completely up to the imagination of the reader. In our specific case, the reciever hears a "go forward" transmission and it make a connection which tells the motor on the car to spin in a certain way. Thus, the car goes forward. If the reciever hears a different message, it connects a different circuit. This makes the motor spin in a different way - and our car travels backwards!
Intermission:
Ok, we've talked about a lot so far. Radio waves, transmitters and recievers. So, when do I get my RC car to start moving!? For this we need something to do work for us. What can we use? I've got it - a motor! Our RC car has two of them. They are both electromagnetic motors. To learn more specifics about electromagnetic motors [click here.] We'll describe them in brief terms.
How RC Car motors work?
Here, we'll find out how an electromagnetic motor on an RC car can power the wheels and steer the car. The first part is simple. An electric current runs from the battery, through the wires to the motor, and through the motor. When the current runs, the motor turns. Current can flow in two directions. The direction the current flows in the wires determines the direction the motor spins - either forwards or backwards. [show flash movie, or picture of this].
The steering is a little more difficult. For this we need to involve mechanics. But the principle of the electric motor is the same. To turn left we need the motor to spin in one direction. To turn right, we need it to spin the opposite direction. So, we switch the current in the steering motor, just as we switch the direction of the current to make the car go forward / backward. Involve a couple gears, and a lever and we can turn the wheels to the left or the right [more opportunity for gratiuitous flashwork.]
The missing link here is the radio reciever. This is the keystone piece to getting the car moving. Let's find out how this piece fits it all together!
Putting it all together
So, we've got several pieces at this point - a radio trasmitter, a radio reciever, electric motors for the propulsion, and electric motor for the steering. Oh yea, and a battery to power it all. Let's put this all together.
You, the "radio controller" pick up your trusty radio control, and switch on the
power to it and the car. Let's follow what happens next!
1) You push the lever forward.
This activates links in the radio controller which makes a crystal vibrate. We are
now "transmitting" our signal.
2) The radio reciever "wakes up!"
Finally! The radio reciever was bored all day long and now it hears that sweet signal
in the air saying there's work to do. What is it saying? "Go Forward," the signal
says. "Ok," the radio reciever thinks to itself. "Go Forward means connect this
wire over here." Click. We have a connection in the car.
3) Current flows through the motor
Finally, the motor pulses with electricity. The wheels connected to the motors shaft
begin to spin furiously, and the car moves forward. Voila!
That's it. A couple hunks of wire, some motors and batteries and we now have the
basic jist of how an RC works.
In summary:
- hitting the control sends a radio signal that the car picks up. This signal
is interpreted by the reciever and triggers an electromagnetic motor which
actuates either the back wheels to create propulsion, or the steering column
which steers the front wheels.
What's next?
If you've read this far, congratulations. You now know more than most humans on
this earth. How does it feel? What follows next, however, is actually where
it gets really exciting. What do you think it would feel like to control
a car in France sitting in the confort of your living room in London? That, my friend,
is exactly what you'll see by clicking HERE. But first,
we need to understand how a computer, such as the one you are sitting at, can
control an RC car.
Click here to learn how a computer can control
an RC car.
