MAKE blog fixture Michal Zalewski is working on an omnibot that uses a single motor to control the angles of four wheels, allowing it to make sharp turns without the necessity of using mechanum gears. Of course, this being Michal, his whole project is gorgeously CNCed and cast from resin.
The goal of this project is to experiment with a novel configurable drivetrain that allows the robot to perform on-the-spot 360° turns, or to instantaneously switch to sideways motion – all while keeping a very accurate track of its position in almost any terrain. The design relies on just three $1.20 motors and four regular wheels, and is relatively easy to recreate even with Legos. The total price tag is under $120 or so.
Of course, robot designs capable of omnidirectional movement are not rare, but they usually employ very expensive and complex Mecanum wheels, or anywhere from 6 to 8 servomotors to independently position and operate regular wheels, in both cases resulting in a substantial price tag. Some low-budget alternatives exploit wheel slippage instead, but that approach is completely incompatible with many types of terrain, is inefficient, and makes accurate position tracking fairly difficult.