The legged robots with variable stiffness actuators (VSAs) can achieve energy-efficient and versatile locomotion. However, equipping legged robots with VSAs in real-world application is usually restricted by (i) the redundant mechanical structure design, (ii) limited stiffness variation range and speed, and (iii) high energy consumption in stiffness modulation. In this paper, we present a novel Variable-Length Leaf-Spring Actuator (VLLSA) in legged robots that aims to address the aforementioned limitations. The design is based on leaf-spring mechanism and we improve the structural design to make the proposed VSA (i) compact and lightweight in mechanical structure, (ii) precise in theoretical modeling, and (iii) capable of modulating stiffness with wide range, fast speed, and low energy consumption. Hardware experiments validate that the legged robot equipped with the proposed VLLSA has compact structure, high dynamic performance and low energy consumption.

翻译：具备变刚度执行器（VSA）的腿式机器人能够实现高效且多功能的运动。然而，在实际应用中，为腿式机器人配备VSA通常受到以下限制：（i）冗余的机械结构设计，（ii）有限的刚度变化范围与速度，以及（iii）刚度调节过程中的高能耗。本文提出了一种用于腿式机器人的新型可变长度板簧执行器（VLLSA），旨在解决上述限制。该设计基于板簧机构，我们通过改进结构设计，使得所提出的VSA具有以下特点：（i）机械结构紧凑轻量化，（ii）理论建模精确，以及（iii）能够以宽范围、高速度和低能耗调节刚度。硬件实验验证了配备所提出VLLSA的腿式机器人具有紧凑的结构、高动态性能和低能耗。