Active energy harvesting device

An active energy harvesting device comprising:

• a rigid body configured to vibrate corresponding to vibration of an external vibration body and including a first end at which an energy harvesting structure is provided to convert mechanical energy due to vibration into electric energy;
• a magneto-rheological material provided at a second end of the rigid body opposite to the first end so as to be bound to the rigid body and including a material which is changed in elastic force according to the surrounding magnetic field strength;
• a fixing unit for binding the second end of the rigid body and the magneto-rheological material and connecting the rigid body to the external vibration body to achieve vibration transmission;
• and
• a first permanent magnet arranged symmetrically apart from the magneto-rheological material while interposing the magneto-rheological material therebetween and provided so as to adjust a gap from the magneto-rheological material and change an elastic coefficient of the magneto-rheological material according to the gap.