Nearly optimal neural network stabilization of bipedal standing using genetic algorithm

In this work, stability control of bipedal standing is investigated. The biped is simplified as an inverted pendulum with a foot-link. The controller consists of a general regression neural network (GRNN) feedback control, which stabilizes the inverted pendulum in a region around the upright position, and a PID feedback control, which keeps the pendulum at the upright position. The GRNN controller is also designed to minimize an energy-related cost function while satisfying the constraints between the foot-link and the ground. The optimization has been carried out using the genetic algorithm (GA) and the GRNN is directly trained during optimization iteration process to provide the closed loop feedback optimal controller. The stability of the controlled system is analyzed using the concept of Lyapunov exponents, and a stability region is determined. Simulation results show that the controller can keep the inverted pendulum at the upright position while nearly minimizing an energy-related cost function and keeping the foot-link stationary on the ground. The work contributes to bipedal balancing control, which is important to the development of bipedal robots.     

倒立摆系统的自摆起和稳定控制

为了实现一级倒立摆系统自摆起和稳定控制，该文采用了最优控制与PID控制相结合的控制方法。首先，采用Bang—Bang控制理论设计开环时间最优控制器，实现倒立摆的平稳快速摆起，同时设计经典PID控制器控制小车位置；然后采取线性二次型最优控制理论设计LQR控制器，将倒立摆稳定在平衡位置。计算机仿真和倒立摆系统实时仿真表明，文中提出的控制策略和控制算法得到了很好的验证，取得了满意的效果。     

Global stabilization of the unstable Reaction-Wheel Pendulum

The paper deals with the problem of the Reaction Wheel Pendulum stabilization about unstable (inverted) position for arbitrary initial conditions. Considered mechanical system consists of a physical pendulum with a symmetric disk attached to the end of the pendulum, which is free to spin about an axis parallel to the axis of rotation of the pendulum. The disk is actuated by a DC-motor. The coupling torque generated by the angular acceleration of the disk is used to control of the pendulum. The switching control law is proposed to swinging up the pendulum and balancing it about the inverted position. The nonlinear swinging up control law is proposed ensuring global stabilization of the pendulum about inverted position. The Energy-based Speed-gradient (EBSG) control scheme is used to designing the swinging-up controller. The modification of the EBSG method is proposed to ensure attainability of the inverted position of the pendulum for all initial states of the system. The balance controller is designed on the basis of the Variable Structure Control with forced sliding mode. Numerical simulation results are presented showing achievement of the posed control goal by means of the control action of small magnitude.     

Design of optimized fuzzy cascade controllers by means of Hierarchical Fair Competition-based Genetic Algorithms

In this study, we present a design of an optimized fuzzy cascade controller based on Hierarchical Fair Competition-based Genetic Algorithms (HFCGA) for a rotary inverted pendulum system. In this system, one controls the movement of a pendulum through the adjustment of a rotating arm. The objective is to control the position of the rotating arm and to make the pendulum maintain the unstable equilibrium point at vertical position. To control the system, we design a fuzzy cascade controller scheme which consists of two fuzzy controllers arrange in a cascaded topology. The parameters of the controller are optimized by means of the HFCGA algorithm. The fuzzy cascade scheme comprises two controllers located in two loops. An inner loop controller governs the position of the rotating arm while an outer controller modifies a set point of the inner controller implied by the changes of the angle of pendulum. The HFCGA being a computationally effective scheme of the Parallel Genetic Algorithm (PGA) has been developed to eliminate an effect of premature convergence encountered in Serial Genetic Algorithms (SGA). It has emerged as an effective optimization vehicle to deal with very large search spaces. A comparative analysis involving computing simulations and practical experiment demonstrates that the proposed HFCGA based fuzzy cascade controller comes with superb performance in comparison with the conventional Linear Quadratic Regulator (LQR) controller as well as HFCGA-based PD cascade controller.     

Attitude control of a triple inverted pendulum

The paper is concerned with the attitude control of a triple inverted pendulum. The lowest hinge is free for rotation and the torques of the upper two hinges are manipulated not only to stabilize the pendulum but also to control its attitude. The control system is designed by using CAD developed by the author and is realized by a minicomputer. The designed controller is a robust servo controller for a linearized model in the neighbourhood of the upright position of triple inverted pendulum. Experimental results show that the designed controller works satisfactorily.     

倒立摆的一种模糊控制方法

提出一种模糊控制方案,实现对倒立摆系统的平衡控制.针对倒立摆系统多变量的特性,采用双模糊控制器方案,分别对摆杆倾角和小车位移设计模糊控制器,大大降低了设计难度;为了实现对摆角和位移双重控制的功能,采用两个控制器轮流控制的策略,当摆角偏差或角速度值较大时,摆角控制器起作用,保持摆杆的垂直,反之,位移控制器起作用,调整小车位置不越界.在实际的物理设备上进行了实时控制实验,实验结果验证了方案的正确性和有效性.     

Stabilization of the inverted spherical pendulum via Lyapunov approach

In this paper a nonlinear controller is presented for the stabilization of the spherical inverted pendulum system. The control strategy is based on the Lyapunov approach in conjunction with LaSalle's invariance principle. The proposed controller is able to bring the pendulum to the unstable upright equilibrium point with the position of the movable base at the origin. The obtained closed‐loop system has a very large domain of attraction, that can be as large as desired, for any initial position of the pendulum which lies above the horizontal plane. Copyright © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

基于DSP实现的一阶倒立摆控制

倒立摆是控制领域中典型的被控对象。本文通过智能控制算法实现倒立摆的起摆控制。当摆杆的角度进入稳定区域时,通过PID控制算法使摆杆稳定。整个控制过程由基于DSP(DigitalSignalProcessor)为核心的控制器来实现。经过实物检验,成功地实现了一级倒立摆的稳摆和起摆控制。     

一级直线倒立摆匀速行走的模糊控制研究与实现

当前针对倒立摆的研究一般是把角度控制或者位置控制作为控制目标,很少着眼于速度控制,有鉴于此,设计了一种简单的模糊控制器,应用于一级直线倒立摆的匀速行走控制中;仿真实验和实物实时控制实验均验证了该控制器的有效性,对于设定的速度整定值,通过调整几个比例环节的系数,系统具有很好的动态性能指标,而且控制器在有外界扰动时体现了很好的抗扰性;考虑到实际物理系统中倒立摆行程的限制,设计的自动换向开关实现了倒立摆在一段给定的行程上匀速来回行走的控制目标,通过手动切换开关也能实现倒立摆的位置控制。     

Non-local stabilization of a spherical inverted pendulum

We design a non-linear stabilizing control law for a four degree of freedom spherical inverted pendulum. The pendulum is a slim cylindrical beam attached to a horizontal plane via a universal joint; the joint is free to move in the plane under the influence of a planar force. The upright position is an unstable equilibrium of the uncontrolled system because of gravity. The objective is to design a controller so that it stabilizes the upright position starting from any position in the upper hemisphere with arbitrary velocity. We achieve this by first transforming the original system to an appropriate upper triangular form and then designing a controller which incorporates a high gain design with the method of non-linear forwarding. The control law is evaluated through computer simulations.