Development of a novel variable stiffness actuator with automatic rigidity/compliance switching

Abstract

Flexible driving is essential in enhancing security during human-robot interactions and improving the adaptability of robots to complex environments. Based on these principles, we developed a variable stiffness actuator with automatic rigidity/ compliance switching. The actuator contains two motors-one for position control and the other for adjusting the stiffness. The stiffness adjustment motor independently alters stiffness through regulating the distance between the output shaft and the spring sliders. The function of automatic rigidity/compliance switching is realized through turning four electromagnets on or off to make sucker up or down. We set up an experimental platform to verify the automatic switching function for rigid and compliant characteristics. Results showed that the actuator can cover a wide range of stiffness and provide reliable rigidity/compliance switching.

Improving the performance of industrial machines with variable stiffness springs

“…As explained in Vanderborght et al (2013), there are several ways to change the transmission ratio: by changing lever length, by introducing a nonlinear mechanical link, or by using a continuously variable transmission (CVT). Practical implementations of this type of actuator based on a planetary dierential can be found in Kim and Song (2012); Cui et al (2014).…”