Motion Control Motors

An electric motor converts electricity into mechanical motion, mostly by electromagnetism. Rotary electric motors consist mainly of two parts, the rotating part on the inside is called the rotor and the stationary part on the outside is called the stator. The motor contains electromagnets that are wound on a frame called the armature which creates magnetic forces to repel and attract opposite poles. The placement of the armature and the opposing magnets varies depending on the type of motor but one will always be on the rotor and the other on the stator. When power is applied to the windings it turns them into an electro magnet which repels the like pole of the opposing magnet and attracts the unlike pole, causing the rotor to turn. The polarity of the electromagnet is reversed to change the magnetic poles and the motion continues.

There are various types of motor which can be grouped by the physical workings:-

• Brush Motors
  Windings are located on the rotor with stationary magnets in the stator. The motor uses two stationary brushes that physically connect with the rotors contacts as it turns and acts as the switch to alternate the current to the coils.
• Brushless Motors
  Windings are located in the stator and permanent magnets are located in the rotor. The polarity of the windings is sequentially changed to move the rotor.
• Stepper Motors
  The grooved rotor is positioned via a sequence of energised electromagnets in the stator producing controllable movement increments.
• Linear Motors
  Essentially an electric motor that has had its stator unrolled so that instead of producing rotation, it produces a linear force along its length.
• Slotless Motors
  Contains a type of lamination that eliminates cogging (jagged motion) torque due to magnetic attraction of the rotor to the stator slots.