An active vibration isolation system for isolating a suspended platform from vibration input to the vibration isolation system base includes an exoskeleton, a rotary actuator, and a drive mechanism separate from the exoskeleton for providing force output from the rotary actuator to the suspended plant. The rotary actuator may include inner and outer rotors which rotate relative to each other. The rotary actuator may be free to translate relative to the vibration isolation system base and the suspended platform, and both the inner and outer rotors may be free to rotate relative to the exoskeleton.