This paper proposes a new type of energy-efficient actuator called variable gravity compensation module integrated actuator (VGCA). VGCA saves the energy by compensating the gravitational torque at the target joint. Furthermore, by covering the variation of payload, the VGCA can maximizing the amount of energy saving. The VGCA consists with a compact variable gravity compensation module, called CVGCm, which is a cylindrical compact modular unit based on the cam and variable pivot of the lever mechanism and motor. Through the experiment, we proved the CVGCm can provided a rapid change of the compensation torque. Furthermore, VGCA showed a reduction of current and power in static and dynamic motion compared to the actuator without CVGCm.

Funding Information
* The Samsung Science and Technology Foundation under Project (No. SRFC-TC1903-02),
* The R&D Program for Forest Science Technology (No. 2021364B10-2123-BD01) provided by the Korea Forest Service