Turn the robot with the mouse or your finger. Click an axis (a coloured circle or a card) to light up its ring and its axis and to read its description, press X-ray to look inside at the motors, gearboxes, controller and cables, and move each joint with its slider.
Choose how the robot body must move; the wheels follow. Then pick a configuration below to compare.
(δm, δs) = (2, 0). Two driven fixed wheels and a castor. Turns by driving the wheels at different speeds. Cannot slide sideways: not holonomic.
(δm, δs) = (1, 1). One steered and driven front wheel, two fixed rear wheels. Tow tractors and AGV forklifts. Not holonomic.
(δm, δs) = (1, 1). Two steered front wheels, two driven rear wheels. The inner wheel turns more than the outer one. Cannot turn on the spot.
(δm, δs) = (1, 1). Three wheels, all steered and driven together by a common mechanism: the robot goes in any direction without turning its body.
(δm, δs) = (3, 0). Three omni wheels at 120°. Holonomic: any motion, instantly. Used in RoboCup and small platforms.
(δm, δs) = (3, 0). Four Mecanum wheels in an X layout. Holonomic: sideways motion comes from the wheel speed combination. Needs a flat floor.
(δm, δs) = (2, 1). Four wheels, each steered and driven. Holonomic once the wheels have turned. Competition robots and heavy AGVs.
(δm, δs) = (2, 0). Two tracks (or four fixed wheels) that turn by slipping on the ground. Rugged but the slipping makes the odometry poor.
The wheel speeds are computed live from the three commands (vx forward, vy to the left, ω turning left) with the inverse kinematics of each configuration, and the robot drives for real; the orange line is its path. A configuration that cannot do a motion (a sideways slide, for example) ignores it and says so. The model is simplified: wheel radius 0.07 m, see the wheels page for the equations.