Unified Phase Variables of Relative Degree Two for Human Locomotion.
Unified Phase Variables of Relative Degree Two for Human Locomotion.
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DOI：
10.1109/embc.2016.7592160
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发表时间：
2016-08
期刊：
影响因子：
--
通讯作者：
Gregg RD
中科院分区：
文献类型：
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作者：
Villarreal DJ;Gregg RD
实现稳定运动的出发点是在步态周期中同步腿部关节运动学。一些双足机器人参数化一个非线性控制器（例如，输入输出反馈线性化），其主要目标是跟踪特定的运动轨迹，作为单个机械变量（即，相位变量）的函数，以允许机器人行走。一种能够参数化整个步态周期的相位变量，即臀部相位角，已被用于控制可穿戴机器人，并且最近被证明可以提供人类步态相位的鲁棒表示。然而，这种统一的相位变量依赖于髋关节速度，这很难实时测量，并且阻碍了在可穿戴机器人的相位控制器中使用导数修正。这个相位变量的一个导数产生加速度（即运动方程），因此系统被称为相对度为1。这意味着系统中存在无法控制的状态。本文的目标是提供相对二度的髋关节相位角替代方法，并检验它们对参数化人类步态的鲁棒性。
A starting point to achieve stable locomotion is synchronizing the leg joint kinematics during the gait cycle. Some biped robots parameterize a nonlinear controller (e.g., input-output feedback linearization) whose main objective is to track specific kinematic trajectories as a function of a single mechanical variable (i.e., a phase variable) in order to allow the robot to walk. A phase variable capable of parameterizing the entire gait cycle, the hip phase angle, has been used to control wearable robots and was recently shown to provide a robust representation of the phase of human gait. However, this unified phase variable relies on hip velocity, which is difficult to measure in real-time and prevents the use of derivative corrections in phase-based controllers for wearable robots. One derivative of this phase variable yields accelerations (i.e., the equations of motion), so the system is said to be relative degree-one. This means that there are states of the system that cannot be controlled. The goal of this paper is to offer relative degree-two alternatives to the hip phase angle and examine their robustness for parameterizing human gait.