Omni wheels are very useful as they let vehicles move forward, backward left, right and turn — all without steering. There are two limitations that all four omni wheels need to be driven, and omni wheels aren’t able to handle bumps or rough terrain well. Tank tracks are ideal for rough terrain, and so James Bruton thought to combine the two ideas. To test the idea, he created an Arduino-controlled robot that was based on the shape of a triangle made up of tracks from tanks.
This robot comes with three tracks for tanks that are driven by a basic gear-driven DC motor. Burton placed them in a triangular pattern which means that each track is set at a 60 degree angle to the two other tracks. Normally, a configuration like this is an accident, since it wouldn’t be able to drive across any direction, without draggin’ at least one track. However, Bruton laid out all the tracks with wheels of a smaller size that have the axes of rotation parallel to the motor axles on the tracks. They can move freely which allows the vehicle to be moved without resistance even if that motion is parallel to the track.
Moving requires coordination between each of the track motors to control the speed of the motor. Bruton employed the Arduino Mega 2560 boards to accomplish the task, as it is loaded with pins to control the motor driver through PWM. There were also enough pins to connect an SPI port to the nRF24L01 radio transceiver which is able to receive commands from Bruton’s general use motor remote.
The robot was able to drive quite smoothly on carpet that was smooth, and it is capable of moving similarly to the way you’d expect to see on the standard omni wheel. However, it was not able to deal with obstructions. The tracks were smooth enough to hold traction against obstacles, and making them with a tough material would have prevented the tracks from sliding when needed. Although the robot wasn’t able to achieve the goal of Bruton’s, it’s nevertheless fascinating to observe the robot in action, and it is an interesting exploration of different kinds of drives.
