Design of Parallel Variable Stiffness Actuators
Design of Parallel Variable Stiffness Actuators
复制标题
并联变刚度作动器的设计
DOI：
10.1109/tro.2022.3197088
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发表时间：
2023-02
影响因子：
7.8
通讯作者：
Chase W. Mathews;D. Braun
中科院分区：
文献类型：
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作者：
Chase W. Mathews;D. Braun
直接驱动电机（DDM）已越来越多地用于机器人致动，因为它们提供高保真度的扭矩控制，但它们通常具有低扭矩密度。齿轮传动可以用来增加电机的扭矩密度，但齿轮传动会降低执行器的功率密度。并联弹性作动器（PEAs）是由一个弹簧与一个电机并联组成，它可以在不影响转矩控制精度的情况下提高作动器的转矩和功率密度。PEA还可以通过共振振荡施加电机的扭矩来产生有效的振荡运动。然而，在PEA中使用的常规固定刚度弹簧仅能够在由弹簧刚度限定的固定谐振频率下进行有效的振荡运动。本文提出了一种并联变刚度作动器（PVSA），它由一个DDM和一个变刚度弹簧并联组成。PVSA保留了DDM和PEA的扭矩控制带宽，可用于在一定范围的振荡频率内放大电机的扭矩和功率。我们提出了一种紧凑的设计的PVSA，其中直接驱动电机，高能量密度复合弹簧，和可变刚度机构被安排在一个传统的圆柱形几何形状，类似于电机齿轮箱组件。我们预见PVSA在移动的机器人和可穿戴设备中的使用，其中不同频率的节能振荡运动沿着高扭矩和功率密度是必不可少的。
Direct-drive motors (DDMs) have been increasingly used for robot actuation because they provide high-fidelity torque control, but they typically have low torque density. Gearing can be used to increase the torque density of motors, but gearing decreases the power density of the actuator. Parallel elastic actuators (PEAs), composed of a spring attached in parallel to a motor, can increase both the torque and power density of the actuator without jeopardizing torque control fidelity. PEAs can also generate efficient oscillatory motion by applying the torque of the motor through resonant oscillations. However, conventional fixed stiffness springs used in PEAs only enable efficient oscillatory motion at a fixed resonant frequency defined by the stiffness of the spring. In this article, we present a parallel variable stiffness actuator (PVSA) consisting of a DDM connected in parallel to a variable stiffness spring. PVSAs retain the torque control bandwidth of DDMs and PEAs and can be used to amplify the torque and power of the motor over a range of oscillation frequencies. We present a compact design of a PVSA where a direct-drive motor, a high energy density composite spring, and a variable stiffness mechanism are arranged in a conventional cylindrical geometry, similar to a motor-gearbox assembly. We foresee the use of PVSAs in mobile robots and wearable devices, where energy efficient oscillatory motion at different frequencies, along with high torque and power density is indispensable.