In The Node Bot, we use a dual-drive mechanism in 4x4 configuration, i.e., there are 4 wheels, and all 4 are driven by independent plastic geared DC motors that do 90 RPM tops. Dual-drive is used mostly in tanks.
Practically and functionally, the 4x4 system is actually a 4x2 (4 wheels, 2 driven) system, as 2 motors on each side are connected parallelly to one output on the L298N motor driver board. So, taking the left side motors as an example, the front-left motor cannot be turned independently of the rear-left motor, i.e., both motors of a side rotate in the same direction.
Turning is achieved by is running motor pairs of either side in the mutually opposite direction. One pair goes forward, the other in reverse. This allows the bot to turn in place. Vibrations have been reduced by using wider wheels of 20 mm width. Previously, 7 mm wheels were used, and the resulting vibrations would shake everything on the thin acrylic “flatbed”. Thanks John Rodrigues for donating the wheels. :)