Fast inverse dynamics computation in real-time robot control

In this paper, two fast algorithms for the inverse dynamics computation in real-time robot control are developed by using simple Lagrange-Euler formulation. The high computational efficiency of the proposed algorithms can make the inverse dynamics computation of any practical robot to be implemented on a current microcomputer in real-time. As compared with other existing algorithms, the algorithms proposed in this paper are, computationally, the fastest of all existing algorithms for robot dynamics computation.     

Embedded Model Control: outline of the theory

Embedded Model Control allows one to proceed systematically from fine plant dynamics and control requirements to the Embedded Model (EM), which is the core of control design and algorithms. The model defines three interconnected parts: the controllable dynamics, the disturbance class to be rejected and the neglected dynamics. Controllable and disturbance dynamics must be observable from the plant measurements. Control algorithms are designed around the first two parts, while stability and performance are constrained by the third one. The key design issue is discriminating between driving noise and neglected dynamics, to guarantee updating disturbance in view of its rejection. To this end, concept and equations of the 'error loop' are outlined: it maps error sources to performance and shows how to discriminate destabilizing sources, while meeting performance requirements. An introductory example with analytical and simulated results illustrates the design steps.     

Adaptive control of electromechanical executive systems

A problem is solved of synthesis of control algorithms providing the efficient functioning of executive systems with changes in parameters of controlled objects and under external disturbances. The algorithms are synthesized on the basis of concepts of inverse problems of dynamics in combination with minimization of local functionals characterizing the energy of motion in the neighborhood of phase paths of reference models. A peculiarity of the algorithms consists in the fact that, in their structures, loops of control functions are formed which hold the functional values in a small neighborhood of the extremum minimum. Analytical studies of dynamics of controlled processes are performed and it is shown that, with an increase in operating speed of loops of control functions, the processes in the system approach the processes in reference models. With fairly high operating speed of such loops, dynamical characteristics of systems remain stable regardless of disturbances of parameters and coordinates.     

Recent developments in multibody dynamics

Multibody system dynamics is based on classical mechanics and its engineering applications originating from mechanisms, gyioscopes, satellites and robots to biomechanics Multibody system dynamics is characterized by algorithms or formalisms, respectively, ready for computer implementation As a result simulation and animation are most convenient Recent developments in multibody dynamics are identified as elastic or flexible systems, respectively, contact and impact problems, and actively controlled systems Based on the history and recent activities in multibody dynamics, recursive algorithms are introduced and methods for dynamical analysis are presented Linear and nonlinear engineering systems are analyzed by matrix methods, nonlinear dynamics approaches and simulation techniques Applications are shown from low frequency vehicles dynamics including comfort and safety requirements to high frequency structural vibrations generating noise and sound, and from controlled limit cycLes of mechanisms to penodic nonlinear oscillations of biped walkers The fields of application are steadily increasing, in particular as multibody dynamics is considered as the basis of mechatronics     

纳米工程中大规模分子动力学仿真算法的研究进展

综述了借助分子动力学仿真方法研究纳米工程领域中的单晶材料纳米压痕、拉伸、切削和磨削,非晶材料的纳米压痕和多晶材料的塑性变形等方面.介绍提高单机仿真规模的Verlet列表法、Cell Linked链表法、网格邻近列表链表法和列表势等串行算法,还描述原子分解法、作用力分解法和空间区域分解法等通过增加CPU的数量使仿真规模得到大大提高的并行算法.同时,从串行算法和并行算法两方面对国内外学者在该领域的研究现状进行较全面的综述.最后,指出目前的分子动力学仿真规模还不足以满足需求,仿真算法还需本质上的突破.     

The connected graph method in mathematical modeling of system dynamics for systems with distributed link masses

Dynamic equations of a holonomic system in generalized coordinates with distributed link masses are obtained with the connected graph method. It is shown that these equations are identical to the equations obtained from the dynamic equations of this system in the Lagrange form. The structure of these equations is analogous to the structure of the equations of dynamics of a holonomic system with localized masses. They can be used as a mathematical base for algorithms for producing equations of multilink mechanism dynamics.     

Innovation sequence application to aircraft sensor fault detection: comparison of checking covariance matrix algorithms

In this paper, the algorithms verifying the covariance matrix of the Kalman filter innovation sequence are compared with respect to detected minimum fault rate and detection time. Four algorithms are dealt with; the algorithm verifying the trace of the covariance matrix of the innovation sequence, the algorithm verifying the sum of all elements of the inverse covariance matrix of the innovation sequence, the optimal algorithm verifying the ratio of two quadratic forms of which matrices are theoretic and selected covariance matrices of Kalman filter innovation sequence, and the algorithm verifying the generalized variance of the covariance matrix of the innovation sequence. The algorithms are implemented for longitudinal dynamics of an aircraft to detect sensor faults, and some suggestions are given on the use of the algorithms in flight control systems.     

机器人动力学模拟

本文主要讨论了具有球腕式结构的机器人动力学模拟。文中结合六自由度仿人操作手,提出了用系统分解法进行运动反解。以凯恩方程为基础建立机器人动力学模型。     

Algorithm research and realization of the turning control system for heavy transportation vehicle

The dynamics of turning system which is a nonlinear system normally has great impact on the transportation speed of the vehicle having heavy load and large size.The dynamics of turning system depends on control algorithm and its implementation,but the existing control algorithms which having high dynamics in the application of heavy transportation vehicle are complex for realization and high hardware requirement.So,the nonlinear turning system is analyzed for improving its dynamics by researching new efficient control algorithm.The models of electromagnetic valve,hydraulic cylinder and turning mechanical part are built individually to get the open-loop model of the turning system following characteristics analyzed.According to the model,a new control algorithm for heavy transportation vehicle which combined PID with Bang-Bang control is presented.Then the close-loop model of turning system is obtained under Matlab/Simulink environment.By comparing the step response of different control algorithms in the same conditions,the new algorithm’s validity is verified.On the basis of the analysis results,the algorithm is adopted to implement the turning control system by using CAN field bus and PLC controllers.Furthermore,the turning control system has been applied in one type of heavy transportation vehicle.It reduces the response time of turning system from seconds level to 250 ms,and the speed of heavy transportation vehicle increases from 5 km/h to 30 km/h.The application result shows that the algorithm and turning control system have met all the turning requirements.This new type of turning control algorithm proposed is simple in implementation for fast response of nonlinear and large-scale turning system of heavy transportation vehicle.     

产品创新设计平台PCD框架

根据创新计算的旋转动力学理论,提出了产品创新设计平台PCD框架,包括理论基础、平台结构、数学模型和创新推理框架,集成了创造性联想算法、创造算法和发明创造技法的自动化实现。平台结构是开放的、增量式的,需要时很容易扩展。     

Adaptive fuzzy wavelet network control of second order multi-agent systems with unknown nonlinear dynamics

In this paper, consensus problem is considered for second order multi-agent systems with unknown nonlinear dynamics under undirected graphs. A novel distributed control strategy is suggested for leaderless systems based on adaptive fuzzy wavelet networks. Adaptive fuzzy wavelet networks are employed to compensate for the effect of unknown nonlinear dynamics. Moreover, the proposed method is developed for leader following systems and leader following systems with state time delays. Lyapunov functions are applied to prove uniformly ultimately bounded stability of closed loop systems and to obtain adaptive laws. Three simulation examples are presented to illustrate the effectiveness of the proposed control algorithms.     

Multibody dynamics in arterial system

There are many things in common between hemodynamics in arterial systems and multibody dynamics in mechanical systems Hemodynamics is concerned with the forces generated by the heart and the resulting motion of blood through the multi-branched vascular system The conventional hemodynamics model has been intended to show the general behavior of the body arterial system with the frequency domain based linear model The need for detailed models to analyze the local part like coronary arterial tree and cerebral arterial tree has been required recently Non-linear analysis techniques are well-developed in multibody dynamics In this paper, the studies of hemodynamics are summarized from the view of multibody dynamics Computational algorithms of arterial tree analysis is derived, and proved by experiments on animals The flow and pressure of each branch are calculated from the measured flow data at the ascending aorta The simulated results of the carotid artery and the ihac artery show in good accordance with the measured results     

Multibody contact dynamics on mechanisms with deep groove ball bearing joints

The dynamics of ball bearings are important to fatigue breakage, dynamic performance and motion precision of mechanisms connected by ball bearings joints with multi-clearances. In this study, a new method is proposed for multibody dynamics analysis on mechanisms under the effects of radial internal clearances and impact of balls/cage pockets interactions of ball bearings. Including balls/rings interactions and balls/cage pockets interactions, the three dimensional dynamics models of the crank slider mechanism are established and calculated by generalized-α algorithms on the basis of Hertzian contact theory and penalty function method. The rules of eccentric trajectories of inner and outer ring center for one ball bearing joint are verified with the results calculated by XU’s references. The results of dynamic errors, motion trajectories, dynamic forces are achieved under different speeds, radial clearances and number of ball bearings. The speeds and radial clearances are critical to the dynamic performances and motion precision of mechanisms, especially the number of ball bearings. The number of ball bearings is important to impact force and motion stability of the mechanism.     

Tracking control of nonholonomic mobile agents with external disturbances and input delay

This paper investigates the tracking control problem of chained-form nonholonomic multiagent systems (MASs). In contrast to the existing works in which some algorithms have been designed for ideal conditions, the destructive factors including external disturbances and input delay are considered in the dynamics of the agents in this work. Two distributed controllers are proposed such that the states of the controlled agents can track the states of the target in the presence of external disturbances and input delay. For this purpose, a distributed controller is firstly suggested based on a switching method to solve the tracking control problem for nonholonomic MASs with external disturbances. Then, the proposed control law is extended based on a state predictor for the tracking control of agents in the presence of input delay. The stability analysis of the two distributed controllers is also provided. Simulation results show the promising performance of the proposed algorithms.     

基于任务的可重构模块机器人构形确定方法

可重构机器人为柔性加工系统提供了更多的选择,但复杂多变的任务、环境以及机器人模块无穷组合,为机器人构形的确定带来了很大的难题。采用遗传算法和迭代算法分两级搜索对机器人构形组合进行优化设计:运用遗传算法对机器人构形进行进化设计,满足工作空间的可达性、环境避障、线性和角度误差、末端操作灵巧度、运动关节的动力学要求、期望模块数目等性能指标要求。运用迭代算法对构形进行运动学逆解求解,计算空间工作点的可达性适应度。根据可装配的模块机器人及模块化思想,建立各个模块的速度、加速度等动力学表达式及相关修正公式,采用补偿迭代法来自动生成动力学方程,计算运动模块驱动性能的适应度。用专家经验对搜索得到适应度较高的构形进行修正,得到满足工作要求的机器人构形。最后给出实例验证。     

Shift speed improvement of a metal belt CVT

This paper presents a CVT line pressure control strategy for the increased shift speed. Firstly, an algorithm to increase the CVT shift speed is suggested based on a modified CVT shift dynamics and shift speed maps are constructed. In addition, simplified dynamic models of the line pressure and the ratio control valve are derived by considering the CVT shift dynamics, and low level control algorithms for the ratio and the line pressure control are proposed. Using the shift speed maps and the simplified dynamic models of the CVT system, shift performance is investigated. It is found from the experimental and simulation results that improved shift speed can be achieved by increasing the line pressure.     

Control of a manipulator robot by neuro-fuzzy subsets form approach control optimized by the genetic algorithms

In this paper, we describe a new form of neuro-fuzzy-genetic controller design for nonlinear system derived from a manipulator robot. The proposed method combines fuzzy logic and neuronal networks which are of growing interest in robotics, the neuro-fuzzy controller does not require the knowledge of the robot parameters values. Furtheremore, the genetic algorithms (GAs) for complex motion planning of robots require an evaluation function which takes into account multiple factors. An optimizing algorithm based on the genetic algorithms is applied in order to provide the most adequate shape of the fuzzy subsets that are considered as an interpolation functions. The proposed approach provides a well learning of the manipulator robot dynamics whatever the assigned task. Simulation and practical results illustrate the effectiveness of the proposed strategy. The advantages of the proposed method and the possibilities of further improvements are discussed.     

Algorithms of take-off and landing termination control for single-rotor helicopters

A procedure for the structural synthesis of control algorithms and the calculation of their parameters is stated. It is demonstrated by theoretical analysis and the mathematical simulation of control process dynamics that the synthesized algorithms can implement an assigned dynamic behavior in systems and provide for their stability during parametric and coordinate disturbances.     

A drive with a high-speed pneumatic jet engine. Dynamics and control

A drive consisting of a pneumatic high-speed jet engine, transfer mechanism, and a control device used for switching the gas main ball valve is examined. A mathematical model is constructed, its dynamical criteria are determined, and a survey of the gear dynamics is carried out. The usefulness of simple control algorithms of relay action is demonstrated, with a feedback contour connected to speed, enabling the valve plug to be turned with a smooth and continuous approach to the final position.     

基于数字滤波的非参数模型直流调速系统

针对直流调速系统不同的外部噪声和干扰,采用算术平均滤波和一阶低通滤波修正非参数模型算法,实现对调速系统中非参数模型控制算法的改进,使控制精度得到较大的改善。利用Matlab软件进行仿真实验,验证了该方法对电机这种具有不确知动态的非线性系统的稳定性和抑止外部干扰和噪声的有效性。