兼顾稳定与灵活的欠驱动双足机器人奔跑运动控制研究

发布时间：2018-01-28 11:53

本文关键词： 欠驱动机器人奔跑步态调节推力-恢复未知不平整地面　出处：《浙江大学》2015年博士论文　论文类型：学位论文

【摘要】：欠驱动双足机器人是实现高速高效双足运动的良好平台,但其稳定性与灵活性一直是控制领域的难点。现今快速奔跑欠驱动机器人往往只具备单一固定步态,缺乏对步长和步速的调节,在受到外界扰动或不平整地面环境时极易摔倒。针对这些难点,本文以欠驱动奔跑机器人为研究对象,设计了一系列欠驱动控制策略并提出一类新的奔跑运动准则,兼顾了欠驱动机器人稳定性与灵活性的运动指标。本文研究的工作集中在以下三个方面：首先,针对多自由欠驱动机器人往往只具有单一步态,难以进行步态调节的缺陷,本文设计了欠驱动自由度为2的四连杆被动机器人,这个机器人在平整地面上存在一个不需要外部控制输入的被动极限环。在这个模型上结合受控的拉格朗日方法、基于事件的方法和能量成形控制,实现了欠驱动自由度为2的奔跑机器人稳定的步态调节,增强了欠驱动机器人的运动灵活性。其次,机器人系统稳定性要求其状态为周期性极限环,而灵活性允许其状态为任意非周期轨迹。针对奔跑过程中稳定性与灵活性要求的矛盾,本文提出一类新的奔跑运动性能指标：奔跑持续性指标,以保证机器人能够实现持续的奔跑运动而不摔倒。这与机器人实际平稳运动要求相符,为实现机器人灵活多样的运动形式提供理论依据。在此指标下提出了奔跑持续性准则,基于弹簧-倒立摆模型研究机器人质心位置、速度以及地面反作用力问的相互关系,并计算奔跑可行状态的集合。当机器人系统状态始终在奔跑可行集内,机器人即进行奔跑可持续运动。最后,基于奔跑持续性准则提出奔跑机器人在受扰环境下的平衡控制策略,根据受扰后的质心速度和角度恒速着地碰撞策略设计平衡控制器,使得系统状态始终沿着奔跑可行集的中心部分改变以适应外部受扰环境,首次解决了欠驱动机器人奔跑过程中的推力-恢复问题以及不平整地面环境的适应问题。实验仿真结果验证欠驱动机器人能够在一步之内达到新的奔跑可持续步态,欠驱动机器人在受扰环境下的平衡能力,是其真正适应在人类物理环境的关建所在,推进了欠驱动机器人的实用化。本文提出的控制器设计方法与奔跑持续性准则,在相应的各个章节给出了详细的理论分析与数学仿真验证。
[Abstract]:Underactuated biped robot is a good platform to realize high speed and high efficiency biped motion, but its stability and flexibility are always the difficulties in control field. Nowadays, fast running underactuated robot usually only has a single fixed gait. Due to the lack of adjustment of step size and speed, it is easy to fall when disturbed by the outside world or uneven ground environment. In view of these difficulties, the underactuated running robot is taken as the research object in this paper. In this paper, a series of underactuated control strategies are designed and a new running motion criterion is proposed, which takes into account the stability and flexibility of the underactuated robot. The work of this paper is focused on the following three aspects: First of all, in view of the defects that multi-freedom underactuated robot usually has only a single gait and it is difficult to adjust gait, a four-link passive robot with underactuated degree of freedom of 2 is designed in this paper. The robot has a passive limit cycle on the leveling ground that does not require external control input. The model combines the controlled Lagrangian method, event-based approach and energy shaping control. A running robot with underactuated degree of freedom of 2 is realized, and the movement flexibility of the underactuated robot is enhanced. Secondly, the stability of the robot system requires its state to be periodic limit cycle, while the flexibility allows its state to be an arbitrary aperiodic trajectory. In this paper, a new performance index of running motion, running persistence index, is proposed to ensure that the robot can run continuously without falling down, which is in line with the requirements of the robot's steady motion. In order to provide a theoretical basis for the realization of flexible and diverse motion forms of the robot, a running persistence criterion is proposed under this index, and the center of mass position of the robot is studied based on the spring-inverted pendulum model. The relationship between the velocity and the ground reaction force is discussed, and the set of running feasible states is calculated. When the robot system state is always in the running feasible set, the robot can run sustainably. Finally, the balance control strategy of the running robot in disturbed environment is proposed based on the running persistence criterion, and the balance controller is designed according to the centroid velocity and angular impact strategy. The system state is always changed along the center of the running feasible set to adapt to the external disturbed environment. The thrust-recovery problem of underactuated robot and the adaptation of uneven ground environment are solved for the first time. The experimental results show that the underactuated robot can achieve a new sustainable running step in one step. State. The balance ability of underactuated robot in disturbed environment is the key point of its real adaptation to human physical environment, which promotes the practical application of underactuated robot. In this paper, the controller design method and running persistence criterion are presented, and detailed theoretical analysis and mathematical simulation are given in the corresponding chapters.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TP242

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