Move It!

There are only two more lessons before you're ready to build a mini-bot! This lesson covers motors (and a few other things) which are at the core of most robot movement. To understand motors and how they work, you need to learn a little about electromagnetism or, more specifically, electrodynamics.

Magnetism

Magnetism was discovered by the ancient Greeks (and also by the vikings, Chinese, etc.) who noted that lodestone (magnetite), a naturally occurring iron ore was attracted to iron. They also discovered that a block of lodestone suspended from a string would point to magnetic North and the compass was born. Trivia: It's called a magnet because lodestone was found in Magnesia, Turkey.

Electromagnetism

The relationship between magnetism and electricity was studied by Hans Christian Oersted, Andre-Marie Ampere and tied together by Michael Faraday and James Clerk Maxwell and polished by Oliver Heaviside and Heinrich Hertz (note: Heaviside should have fired his publicist...all the rest have major units of measure named after them).

Exercise: make an electromagnet by coiling up a lot of wire and passing a current through it. Observe its effects on a compass and/or on iron shavings

Whenever current moves through a conductor (like a wire), it generates a magnetic field. The direction of that magnetic field is perpendicular to the direction of the current flow and can be remembered using the right hand rule. If the wire is coiled up, the magnetic field is enhanced. It can be further enhanced and directed by inserting a ferrous material inside the coil. Much of the early work on electricity and magnetism was done by Michael Faraday. They discovered that when a conductor is carrying a current, and therefore generating a magnetic field is placed inside another magnetic field, an electromotive force results that applies force to push the conductor. The direction of that force is often described using the left-hand rule.

• ​British electromaetism tutorial

Electro-motive force is what lets us use electricity to move things. By far the most common application is the motor. There are actually many types of motors, but in our experiments we will be using common DC motors.

• ​Retro motor tutorial!
• ​a little more modern
• ​Brushless DC Motors

• Transformers (show how to use a signal generator?)

• DEVICES: real-world control:
  • Electromagnets
  • Solenoids
  • DC Motors

Part II

• THEORY: Controlling (high) current w/micro-controller
• DEVICES: H-bridge for direction (make one with 2x SPDT or 1x DPDT switch?)
  • relays
  • power transistor
  • Inductors, flyback, meet ELI the ICE man
  • Protection diodes

Part III

• THEORY: PWM for speed control (view with oscilloscope)
• DEVICES: Arduino motor shields.
• HANDS-ON: Drive DC motors, controlling speed and direction using a motor shield.