ON CONTROLLABLE STIFFNESS BIPEDAL WALKING
ON CONTROLLABLE STIFFNESS BIPEDAL WALKING
复制标题
可控刚度双足行走
DOI：
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发表时间：
2008
期刊：
影响因子：
--
通讯作者：
R. Ghorbani
中科院分区：
文献类型：
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作者：
R. Ghorbani
当前大多数双足行走机器人每次腿部转换时的冲击力是能量耗散的主要原因之一。最大限度地减少影响可以减少能量损失。本研究提出，不是通过控制关节角度轮廓来减少需要大量能量的冲击，而是在机器人结构上安装弹性机构，使机器人能够减少冲击，并将部分能量以弹性形式存储，然后将能量返回给机器人。实际上，这推动了具有可调节刚度弹性的双足行走机器人的开发，这本身就产生了新的挑战性问题。本文通过五个连续阶段解决了一些挑战。首先，开发了一种可调顺应串联弹性执行器（本文命名为ACSEA）。采用电动机的速度控制方式来精确控制ACSEA的输出力。其次，提出了三种不同的可调节刚度人工肌腱（ASAT）的概念设计，每种设计都添加在双足步行机器人模型的踝关节处。碰撞阶段（双足行走中脚跟着地和脚着地之间的步态的一部分）的仿真结果表明，通过适当调整 ASAT 的刚度，可以显着改善双足行走机器人的能量学。第三阶段，为了研究ASAT对减少站立阶段能量损失的影响，引入了双足行走的简化模型，该模型由脚、腿和平行于踝关节安装的ASAT组成。模型中包含具有可调节刚度的线性弹簧，用于模拟双支撑阶段后腿产生的力。脉冲约束的概念用于建立碰撞阶段冲击的数学模型，包括脚跟着地和脚着地。对于第四阶段，基于能量反馈的控制器被设计用于自动调整ASAT的刚度，从而减少脚触地期间的能量损失。在最后阶段，开发了速度跟踪（ST）控制器来调节两足动物在中间站立时的速度。 ST 控制器是一种基于事件的时间无关控制器，基于动能误差指数衰减的几何级数，它调整后腿弹簧的刚度，以控制注入到 Biped 的能量，以跟踪中间站立时的所需速度。另一个控制器也与 ST 控制器集成，以便在需要降低速度时调整 ASAT 的刚度。然后，通过计算返回图的线性近似特征值来分析系统（两足动物和上述三个控制器的组合）的局部稳定性。仿真结果表明，即使腿部初始角度存在不确定性，三个控制器的组合也能成功跟踪双足行走的所需速度。这项研究的结果表明，可调刚度人工肌腱对于减少双足行走过程中的能量损失具有显着效果。它还展示了在双足步行模型中添加弹性元件的优点，有利于调节速度的效率和简单性。这项研究为开发具有可调刚度能力的动态步行机器人铺平了道路，该机器人最大限度地减少了两种主要类型的双足步行机器人的缺点，即被动动态步行机器人（节能但需要大量参数调整以保证步态稳定性）和主动控制步行机器人（能源效率明显低下）。
Impact at each leg transition is one of the main causes of energy dissipation in most of the current bipedal walking robots. Minimizing impact can reduce the energy loss. Instead of controlling the joint angle profiles to reduce the impact which requires significant amount of energy, installing elastic mechanisms on the robots structure is proposed in this research, enabling the robot to reduce the impact, and to store part of the energy in the elastic form which returns the energy to the robot. Practically, this motivates the development of the bipedal walking robots with adjustable stiffness elasticity which itself creates new challenging problems. This thesis addresses some of the challenges through five consecutive stages. Firstly, an adjustable compliant series elastic actuator (named ACSEA in this thesis) is developed. The velocity control mode of the electric motor is used to accurately control the output force of the ACSEA. Secondly, three different conceptual designs of the adjustable stiffness artificial tendons (ASAT) are proposed each of which is added at the ankle joint of a bipedal walking robot model. Simulation results of the collision phase (part of the gait between the heel-strike and the foot-touch-down in bipedal walking) demonstrate significant improvements in the energetics of the bipedal walking robot by proper stiffness adjustment of ASAT. In the third stage, in order to study the effects of ASATs on reducing the energy loss during the stance phase, a simplified model of bipedal walking is introduced consisting of a foot, a leg and an ASAT which is installed parallel to the ankle joint. A linear spring, with adjustable stiffness, is included in the model to simulate i the generated force by the trailing leg during the double support phase. The concept of impulsive constraints is used to establish the mathematical model of impacts in the collision phase which includes the heel-strike and the foot-touch-down. For the fourth stage, an energy-feedback-based controller is designed to automatically adjust the stiffness of the ASAT which reduces the energy loss during the foot-touch-down. In the final stage, a speed tracking (ST) controller is developed to regulate the velocity of the biped at the midstance. The ST controller is an event-based time-independent controller, based on geometric progression with exponential decay in the kinetic energy error, which adjusts the stiffness of the trailing-leg spring to control the injected energy to the biped in tracking a desired speed at the midstance. Another controller is also integrated with the ST controller to tune the stiffness of the ASAT when reduction in the speed is desired. Then, the local stability of the system (biped and the combination of the above three controllers) is analyzed by calculating the eigenvalues of the linear approximation of the return map. Simulation results show that the combination of the three controllers is successful in tracking a desired speed of the bipedal walking even in the presence of the uncertainties in the leg’s initial angles. The outcomes of this research show the significant effects of adjustable stiffness artificial tendons on reducing the energy loss during bipedal walking. It also demonstrates the advantages of adding elastic elements in the bipedal walking model which benefits the efficiency and simplicity in regulating the speed. This research paves the way toward developing the dynamic walking robots with adjustable stiffness ability which minimize the shortcomings of the two major types of bipedal walking robots, i.e., passive dynamic walking robots (which are energy efficient but need extensive parameters tuning for gait stability) and actively controlled walking robots (which are significantly energy inefficient).
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影响因子：
3.3
作者：
HE, JP;KRAM, R;MCMAHON, TA
通讯作者：
MCMAHON, TA
影响因子：
2.4
作者：
BLICKHAN, R
通讯作者：
BLICKHAN, R
DOI：
10.1115/1.1427703
发表时间：
2002-02-01
影响因子：
1.7
作者：
Kuo, AD
通讯作者：
Kuo, AD
影响因子：
2.4
作者：
F. Zajac
通讯作者：
F. Zajac
影响因子：
2.4
作者：
Farley, CT;Morgenroth, DC
通讯作者：
Morgenroth, DC