US Patent 7843277 Haptic feedback generation based on resonant frequency

A system that generates a haptic effect generates a drive cycle signal that includes a drive period and a monitoring period. The drive period includes a plurality of drive pulses that are based on the haptic effect. The system applies the drive pulses to a resonant actuator during the drive period and receives a signal from the resonant actuator that corresponds to the position of a mass in the actuator during the monitoring period.