An improved model-based predictive control of vehicle trajectory by using nonlinear function

A new model-based predictive control algorithm for vehicle trajectory control is proposed by using vehicle velocity and sideslip angle. Based on the error function combined with vehicle velocity and side slip of a bicycle model, a predictive control method has been proven to be useful on low velocity. Thus, it could be applied for an autonomous vehicle without a driver. Although an autonomous robot is not necessary to be driven with a high velocity, a commercial vehicle has to be driven at high velocity. Thus the previous predictive control formulation is not enough for a commercial driving system. This study is proposed to enhance the capacity of the predictive controller for rather high speed vehicles. This paper was presented at the 4th Asian Conference on Multibody Dynamics(ACMD2008), Jeju, Korea, August 20–23, 2008. Mr. Jeong-Han Lee is pursuing a Ph.D. degree in Mechanical Engineering at Pusan National University under the supervision of professor Wan-Suk Yoo. His research interests are focused on the area of adaptive control using multibody dynamics. Dr. Wan-Suk Yoo received his Ph.D. degree in 1985 from the University of Iowa. In 1994, he became a full professor at the Pusan National University, and he was selected an ASME fellow. He is serving as a vicepresident of the KSME.     

Selection of modeling coordinates for forward dynamic multibody simulations

Modeling mechanical systems in a manner that allows the models to be simulated quickly is vital in many fields, such as real-time simulation and control. Modeling these systems using their symbolic equations, rather than the more widely-used numerical methods, generally produces faster solution times. However, the number, complexity, and computational efficiency of these equations is highly dependent upon which coordinate set was used to model the system. Most coordinate selection methods established thus far are based on the assumption that minimizing the number of modeling coordinates will produce models with faster simulation times. This paper will show that this technique is not always valid and proposes a new technique of selecting a system’s coordinates based on a series of heuristics. A large part of these heuristics will be established by closely analyzing a specific technique used to formulate a system’s equations, and the effect each step of this formulation process will have on the complexity of the final system equations.     

Analysis of nonlinear structural dynamics by the concept of stability measure

Engineering structures may collapse under dynamic loading, resulting in large displacement motions. The generation of the equations of motion, and an approach for the stability assessment of nonlinear vibrations are presented. The Duffing oscillator is used as an example for the application of the method presented.     

柔性多体系统动力学单向递推组集建模方法

提出了一种柔性多体系统动力学计算机辅助建模方法，即单向递推组建模方法。在运动学正向递推过程中程式化地组集建立链状，树状及含闭环的柔性多体系统用铁相对坐标及模态坐标表达的动力学方程，且有传统的绝对坐标方法及铰相对坐标方法的优点并克服了它们的不足。结果的形式同多刚体系统动力学方程兼容，并适合处理变结构多体机械系统的仿真。由于各条链上递推组集的独立性，本方法极易并已发展为并行计算方法。     

可变形多体系统动力学及接触力学在凸轮机构学中的应用述评

高速、高精度控制与传动中凸轮机构仍然具有无可替代的优越性。但当前面临的问题往往是加工精度已经达到，而速度比国外产品低得多，迫切要求深入分析机构的动态特性。为此必须借助可变形多体系统动力学及接触力学的最新成果。本文结合弹性动力学与接触力学介绍凸轮机构动力学的若干前沿课题。评介已进行的工作，并整理资料为有关研究提供素材。对机构学其他领域的研究也有参考价值。     

螺旋弹簧悬架安装倾角分析

为减小麦弗逊悬架减振器内部摩擦，这里结合悬架多刚体运动学分析和压缩螺旋弹簧径向弯曲变形理论对悬架螺旋弹簧安装倾角进行了参数分析，讨论了倾角参数对弹簧径向位移、对减振器侧向载荷以及对车身冲击作用的影响。     

基于多体模型的汽车半主动悬架控制方法研究

针对半主动悬架控制中的两个重要问题——系统模型的建立和控制策略的确定进行了深入的研究,建立了汽车的多体动力学方程,提出了半主动悬架模糊神经网络控制方法,设计了控制系统,应用遗传算法优化了控制器的参数和结构,用基于变尺度的BFGS算法优化神经网络权值,在仿真研究的基础上进行了试验研究,结果表明提出的方法能明显改善悬架性能。     

Constraint embedding in kinematics and dynamics of hybrid manipulator systems

An approach to kinematics and dynamics based on kinematic influence coefficient matrices is proposed for applications to the analysis and control of motion controlled multibody systems, e.g., hybrid robotic manipulator systems. The scheme is unique in a sense that all the kinematic constraints are completely embedded into the formulations at the kinematics level and equation of motion of the system is obtained in a closed form with respect to the minimal set of independent joint coordinates. Furthermore, all kinematic and dynamic formulations are expressed compactly in the same format by using two special algebraic operators. This isomorphic formalism allows systematic transformations of kinematic and dynamic informations between different sets of coordinates in a purely algebraic way.     

多刚体系统运动学分析的自然坐标法及在悬架运动学分析中的应用

本文介绍了一种适用于计算机分析的多刚体系统运动学分析的自然坐标法。利用自然坐标描述多刚体系统时,只需要一些点和一些单位向量,刚体的约束方程和运动副的约束方程组成了多刚体系统的运动学约束方程。约束方程均为线性或二次方程,因此求解方便。文中利用该方法分析了Maepherson悬架的轮胎横向滑移量、主倾内倾角等与车轮上、下跳动距离的关系。