Many successful bots impress audience so much that the bots are assumed to be incomprehensibly complex inside. The reality is, in most cases, bot internals follow a simple scheme which can be found in almost every bot. In general, all that is required to get a bot running is some way to control it from afar, a way to control the bot's movements, and a power source. These are obviously very general terms as well, so let's take a look at the typical bot.
Let's say Team RoboForge has a new entry: Examp-L-Bot. This entry is nothing unique: it's actually as many bots tend to be in one form or another: a four-wheeled, battery-powered radio-controlled machine with electronic devices controlling the motors. To drive the bot forward, the driver needs only to push forward the joystick on his radio controller. This starts a chain of events which is what I wanted to cover in this article.
First, the radio sends a signal describing which joystick is being pushed, how far, and in which direction. This signal travels through the air in radio waves (which is why it's called a "radio" transmitter as opposed to "video", "infrared" or "X-ray" transmitter). In the bot is a receiver: its only job is to receive the signal through its antenna and then send it off to whatever is plugged into its ports (more on radios and receivers in the next section).
With larger bots, usually the thing plugged into a receiver's port is an ESC, or electronic speed controller. This electronic circuit's job is to interpret the signal from the receiver, then to send the appropriate amount of power (from the batteries, which are only in the system to power it, including ESCs and receiver) further into the system. This is where the intensity of the joystick push matters: the further it is pushed, the more energy the speed controller passes on. That's why the speed controller is called a speed controller: it controls the speed of the next component: the motor.
A motor is a simple gadget. You've all seen a motor at some point in your lives. All the motor does is accept electrical power, which forces the shaft to turn in one direction or the other, depending on which way the voltage is applied. Also, the greater the voltage applied to the motors, the faster and harder they turn (I'll go over this in a lot of detail later). So, when the ESC provides a proportionate amount of power to the motors, which corresponds to the amount the driver pushes the joystick, the motor starts to spin at a proportionate speed. It can all be looked at as percentages. If you push the stick 80% of the way up, the ESC will allow 80% of the available voltage through, and the motor would, in theory, turn at 80% the speed. That way, one could control how fast the motor spins. But the system isn't done yet.
Next, on the shaft of the motor there is sometimes some sort of power transmission. This could be gears, belts and pulleys, or chains and sprockets. The purpose of this stage is to: a) either slow down the motor and increase its turning strength or speed it up and lower its turning strength, and b) protect the motor from strains by not having it directly attached to the last stage of this system. It's a way of transmitting power from the motors to the last stage, described below.
The wheel is obviously the simplest part of the system: the motor, as well as occasionally some power transmission, attaches to it, and the wheel just turns, making the bot move. Why reinvent the wheel? Because some people think other ways are cool. But the typical bot rolls on wheels. This last step makes all of the rest steps pay off.
So, recap summary:
I push the transmitter joystick up 60%. The transmitter sends a signal to the receiver, which tells the speed controllers the received details. The speed controllers send 60% of the battery power to the motors, which turn a series of shafts and gears to reduce the speed and increase the turning force of the motor shaft. Then, at this new reduced speed and increased power, the wheels turn, moving the robot at a certain speed. It's even simpler than it sounds.
So, this is what goes into the typical bot. It's not rocket science, and you don't have to build components like the receiver or the speed controllers: they come preassembled. It's just a matter of plugging things in. It's just one step closer on the road to understanding how to build a bot.
