A walk-behind lawnmower comprising one or more wheels, one or more cutting blades, a motor configured to rotate the one or more cutting blades, a sensor configured to sense an acceleration of the motor, and a controller coupled to the motor and the sensor. The controller is configured to receive, from the sensor, a signal indicative of the acceleration of the motor, determine, based on the signal, whether an amplitude of the acceleration of the motor is greater than or equal to an amplitude threshold, and increment, in response to the amplitude being greater than or equal to the amplitude threshold, a hopping counter. The controller is configured to determine whether the hopping counter is greater than or equal to a hopping threshold, and disable, in response to the hopping counter being greater than or equal to the hopping threshold, operation of the motor.