一类新的PPA型三连杆欠驱动机器人的控制策略

PPA型机器人是一类新型的三连杆欠驱动机械系统,具有3个自由度,但只有1个驱动装置.针对这类欠驱动机器人的运动控制,提出一种分区的控制策略,使之从垂直向下的位置摇起到垂直向上的位置,并实现稳定控制.首先,将系统的运动空间划分为摇起区和吸引区;其次,应用一种基于Lyapunov函数的控制方法来增加系统能量和控制驱动杆姿态,实现摇起操作;再次,采用最优控制方法设计平衡控制,实现稳定的平衡控制;最后,通过仿真实验验证了所提出控制方法的有效性.     

欠腱驱动多指灵巧手的设计

提出一种欠腱驱动多指灵巧手，它具有结构简单，操作灵巧，控制容易，较高的操作适应性，每个多指节手指仅用一个腱驱使手指弯曲运动。文中描述了欠腱驱动多指灵巧手的结构设计与手指位移分析，与现有的多指灵巧手和欠驱动多指杆机器人手相比，这种手指灵巧手的结构更为简单紧凑，且能减少控制的复杂性、重量和成本，并能实现多功能地抓取不同物体的能力。     

基于DSP技术的2R欠驱动机器人控制系统设计

采用DSP作为主处理器,设计出一种欠驱动机器人控制系统,满足了机器人实时动力学控制对高速运算的要求.实验结果表明,所设计的欠驱动机器人控制系统功能完善,实时性好,控制系统稳定且效果良好.     

A solution to leader following of underactuated surface vessels with actuator magnitude and rate limits

This article investigates the leader following of underactuated surface vessels that operate in the presence of environmental disturbances, model uncertainties, and actuator saturation. What makes the design of controller challenging is that the sway cannot be directly controlled. Furthermore, the actuator is formulated with magnitude saturation and rate saturation. To express the effect of magnitude saturation and rate saturation, a continuous function is employed to model actuator. An auxiliary dynamic system is used to solve the problem of magnitude saturation and rate saturation. A disturbance observer is designed to provide estimation of the environmental disturbances and model uncertainties, and achieve finite time convergence of estimation error. A control law is designed based on disturbance observer, backstepping technique, and auxiliary dynamic system. The uniform ultimate boundedness of all signals in the closed-loop control system is proved. Simulations demonstrate the performance of the proposed controller.     

Position control for planar four-link underactuated manipulator with a passive third joint

This paper presents a position control strategy based on the differential evolution (DE) algorithm for a planar four-link underactuated manipulator (PFUM) with a passive third joint, which is to move its end-point from any initial position to any target position. Based on the structural characteristic of the PFUM, a model reduction method is conceived to reduce the PFUM to a planar virtual three-link manipulator and a planar Acrobot in turn. Considering the existence of the angle constraint in the planar Acrobot, the DE algorithm is used to optimize and coordinate the control objective of each reduced system, and also to ensure the target angles of the planar Acrobot corresponding to the target position of the PFUM can be found. Simulations demonstrate the validity of the proposed control strategy.     

面向不平地面的双足欠驱动步行稳定控制

为实现双足机器人在不平地面上的欠驱动步行,提出一种基于质心运动状态的稳定步行控制策略。考虑地面柔性,使用柔性接触模型描述“机器人足部地面”柔性接触,并通过解耦建模的方式建立了“机器人地面”前向与侧向耦合动力学模型。根据人类变速步行特征,提出基于机器人质心速度控制的步行控制策略,将三维步行解耦为前向和侧向的主从控制,通过控制质心位移实现质心速度控制,进而实现稳定步行。搭建三维欠驱动双足步行机器人样机,在地面高度变化不大于0.032 m的不平地面上成功实现了平均步行速度0.216 m/s、步幅为0.31倍腿长的欠驱动步行。试验结果表明,所提控制策略可通过质心速度控制来实现不平地面上的欠驱动稳定步行。     

欠驱动蛇形机器人模块的设计研究

依据现有的欠驱动理论,结合摩擦盘运动分解合成机构,设计出一种欠驱动蛇形机器人模块,并研究其运动规律。通过分析研究表明运用这样的摩擦盘传动机构作为关节模型,可以建立起欠驱动蛇行机器人模块。由于采用了欠驱动方式使得结构紧凑,有利于降低机身的重量;使其具有更大的灵活性和适应性,对蛇形机器人走向实用具有重要的意义。     

Sliding mode coordination control for multiagent systems with underactuated agent dynamics

In this paper, we develop a new integrated coordinated control and obstacle avoidance approach for a general class of underactuated agents. We use graph-theoretic notions to characterise communication topology in the network of underactuated agents as determined by the information flow directions and captured by the graph Laplacian matrix. Obstacle avoidance is achieved by surrounding the stationary as well as moving obstacles by elliptical or other convex shapes that serve as stable periodic solutions to planar systems of ordinary differential equations and using transient trajectories of those systems to navigate the agents around the obstacles. Decentralised controllers for individual agents are designed using sliding mode control approach and are only based on data communicated from the neighbouring agents. We demonstrate the efficacy of our theoretical approach using an example of a system of wheeled mobile robots that reach and maintain a desired formation. Finally, we validate our results experimentally.     

Acrobot动态伺服控制及其对称虚约束方法研究

研究了Acrobot这一垂直平面欠驱动机械臂的动态伺服控制问题. 该问题期望驱动Acrobot到达构形空间中任意目标位置. 由于Acrobot不能稳定在除平衡点外的位置, 因此考虑将系统镇定到经过目标点的周期轨道上. 利用虚约束来描述这样的轨道, 进而给出了在所选虚约束作用下系统的零动态和积分曲线. 接着设计了级联形式的控制器, 内环控制器基于改进的反馈线性化方法, 引入了一个使内环呈现二阶系统特性的虚拟输入, 在该虚拟输入的基础上, 设计了基于Lyapunov稳定性理论的外环控制器. 最后通过数字仿真证明所提出的方法合理有效, 并且获得比基于能量的动态伺服方法更优的结果.