Choice of Motor Controller

A key decision underlying the robot design is what motor controller and motors to go for. We considered the following criteria when choosing our motor controller.

  1. 4 Wheel Drive Control: We plan toi adopt a 4-wheel design. It is possible to use a dual channel motor controller with 4 wheels by tying front and back motors on each side together (parallel circuit).

  2. Stall Current: The motor controller should have a maximum current rating in excess of the stall current of the motor(s) that it controls on each channel. The max current rating is PER CHANNEL. If you have multiple motors in parallel on each channel, add their stall currents together. Our chosen motors are 12V Piborg Monsterborg 300RPM.

  3. Voltage Range: The motor controller should be capable of delivering the voltage required by your motors. Our chosen motors are 12V.

  4. Useful Links: see useful links section above for written guides and presentations by Brian Corteil (Coretec Robotics) which cover details about motors and controller boards.

  5. Popular Choices: The PiWars survey of motor controller boards used by last year’s competitors (2018).

In the end, we plumped for The Piborg Thunderborg controller for a number of reasons

  1. High current rating (5A) compared with alternatives (c. 2A). This helps to mitigate the risk of borking our motor controller if our robot gets stuck.

  2. A wide input voltage range compatible with our chosen motors (Thunderborg can supply anything from 7V through to 35V).

  3. The ability to additionally supply the Pi with 5V power, should we so wish. That said, for reliability we plan to supply our Pi with independent power from a 5V 2A USB power bank.

  4. Popular choice amongst previous PiWars competitors, easy to use with a great library of example code to get it working with our games controller.

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