In a differential drive system, how would you turn the robot to the left?

• A. Speed up the right wheel and slow the left wheel.
• B. Slow the right wheel and speed up the left wheel.
• C. Turn by moving only the right wheel.
• D. Turn by moving only the left wheel.

Answer: (B)

In a differential drive robot, turning is produced by a difference in how fast the two wheels move. The wheel on the right pushing faster than the left creates a yaw that turns the robot toward the left.

So, to turn left effectively, the right wheel should go faster than the left wheel (i.e., increase the right-wheel speed while decreasing the left-wheel speed). If you instead slow the right wheel and speed up the left wheel, the robot would tend to turn to the right. Moving only one wheel can cause the robot to pivot around the other wheel, which is a type of turning but not the smooth left-turn behavior described here.