A wide variety of actuator types may be employed to provide {HEAD ~ synchronized vibration}, including linear actuators, {TAIL ~ rotary actuators}, rotating eccentric mass actuators, and rocking mass actuators 
including
A wide variety of actuator types may be employed to provide { HEAD ~ synchronized vibration } , including linear actuators , { TAIL ~ rotary actuators } , rotating eccentric mass actuators , and rocking mass actuators
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH REL OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH