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