Energy harvesting has been attracting attention as a technology that is capable of replacing or supplementing a battery with the development of various mobile electronics. In environments where stable electrical supply is not possible, energy harvesting technology can guarantee an increased leisure and safety for human beings. Harvesting with several watts of power is essential for directly driving or efficiently charging mobile electronic devices such as laptops or cell phones. In this study, we reviewed energy harvesting technologies that harvest biomechanical energy from human motion such as foot strike, joint motion, and upper limb motion. They are classified based on the typical principle of kinetic energy harvesting: piezoelectric, triboelectric, and electromagnetic energy harvesting. We focused on the wearing position of high-power wearable biomechanical energy harvesters (WBEHs) generating watt-level power. In addition, the features and future trends of the watt-level WBEHs are discussed.

This paper describes the design and control of a nanoprecision XYΘ scanner consisting of voice coil motors and air bearing guides. The proposed scanner can be installed on a conventional XY stage with long strokes to improve the positioning accuracy and settling performance. Major design considerations in developing a high precision scanner are sensor accuracy, actuator properties, structural stability, guide friction, and thermal expansion. Considering these factors, the proposed scanner is made of invar, which has a small thermal expansion coefficient and good structural stiffness. Four voice coil motors drive the scanner, which is suspended by four air bearing pads, in the x, y, and θ directions. The scanner’s position is measured by three laser interferometers which decouple the scanner from the conventional stage. The mirror blocks reflecting the laser beams are fixed using viscoelastic sheets, ensuring that the scanner has a well-damped structural mode. A time delay control algorithm is implemented on the real-time controller to control the scanner. The effectiveness of the proposed scanner is verified experimentally.