Which statement best describes a differential drive system?

• A. A drive that uses gimbal joints to steer.
• B. A drive that relies on the velocity difference between two motors.
• C. A drive that moves in a field of magnets.
• D. A drive that allows movement in many directions at once.

Answer: (B)

A differential drive uses the difference in speeds of two driven wheels to steer. This setup relies on commanding the left and right wheels independently: when both spin at the same rate, the robot moves straight; when they differ, the robot travels along a curved path toward the slower side; and if the wheels rotate in opposite directions, it can spin in place. That velocity difference between the two motors is what creates turning and steering in this configuration. Other descriptions describe different propulsion ideas (gimbaled steering, magnetic tracks, or holonomic/omnidirectional motion), which don’t capture how a two-wheel differential drive actually steers through differential wheel speeds.