A self propelled upright vacuum cleaner is provided with a Hall effect sensor to provide a Hall voltage that varies according to the position of a handgrip maintained by the vacuum cleaner. A microprocessor generates a PWM control signal to control the movement of the vacuum based on the magnitude of the Hall voltage with respect to various response characteristics, including a non-linear logistic function. As such, the vacuum cleaner imparts a user-friendly responsiveness to the user during the operation of the vacuum cleaner.