Mechanical design and energy storage efficiency research of a variable stiffness elastic actuator

The energy storage efficiency is an important performance of a robot or a man–machine interaction device. This article will introduce the process of design and energy storage research of a variable stiffness elastic actuator with a two-elements and one actuator mod. Firstly, the principle model will be present to analyze the operation theory. Then, the simulation and experiment model will be described to calculate the characteristics of the device. The stiffness ratio of the two springs constituting the elastic element of the device will be studied in detail, and the results can present the rule of the energy storage value. Finally, the performance of the device, the error of the experiment, and a special mechanism which presented at the extreme shape condition of the ratio will be discussed. The conclusion is that the maximum energy that the device can store is 1.415 J at the stiffness ratio equaling 0.46, and the energy storage efficiency is 1.3608 at the ratio equaling 0.45, when the weight of the device is 3.54 kg and the apparent stiffness is about 3450 N/m.