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