Abstract
The demand for high-force and compact actuators with large strain is increasing in robotics. PZT is known as one of the promising materials for this purpose with respect to bandwidth, stress, and reliability. However, the most critical drawback of PZT is its extremely small strain, i.e. only 0.1 %. This paper presents a nested rhombus structure for strain amplification of PZT stack actuators. This structure provides a "power-law" strain amplification, resulting in over 20 % strain, which is particularly useful for gaining a large strain in a compact body, appropriate for many robotic applications. The notational convention and fundamental force-displacement analysis will be presented. In addition, the feasibility of the design concept will be addressed through the design of a proof- of-concept prototype.