SiMPLeR: A Series-Elastic Manipulator with Passive Variable Stiffness for Legged Robots
This work addresses the need for robust and simple variable stiffness actuators to enable reliable and cheap robots with animal-like capabilities, such as running and jumping.
The authors tackled the problem of creating a mechanically simple and cheap series elastic actuator with controllable stiffness for legged robots, resulting in a prototype that matched theoretical predictions and demonstrated application in robotic one-legged hopping.
We propose a mechanically simple and cheap design for a series elastic actuator with controllable stiffness. Such characteristics are necessary for animals for running, jumping, throwing, and manipulation, yet in robots, variable stiffness actuators are either complicated or mimicked at low bandwidth through feedback controllers. A robust and simple design is needed to build reliable and cheap robots with animal capabilities. The key insight of our design is attaching torsional springs to timing belts to create a variable stiffness linear spring. In an antagonistic pair, varying the distance between motor and joint then varies the actuator stiffness. We build a prototype of our proposed actuator, show the theoretical behavior matches the experimental characterization, and demonstrate an application to robotic one-legged hopping.