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。     

A recursive subsystem synthesis method for repeated closed loop structure in multibody dynamics

A recursive subsystem synthesis method has been proposed for efficient analysis for a repeated closed loop structure in multibody dynamics. Virtual work form of equations of motion has been used to reduce subsystem equations of motion. Position, velocity, and acceleration analyses are carried out subsystem by subsystem in the forward recursive fashion. Effective mass matrices and force vectors are computed subsystem by subsystem in the backward recursive fashion. An excavator example is used for a repeated closed loop structure to validate the proposed method. This paper was presented at the 4th Asian Conference on Multibody Dynamics(ACMD2008), Jeju, Korea, August 20–23, 2008. Sung-Soo Kim received a B.S. degree in Agricultural Engineering from Seoul National University in 1981. He then went on to receive his M.S. and Ph.D. degrees in Mechanical Engineering from the University of Iowa in 1983 and 1988, respectively. Dr. Kim is currently a Professor in the Department of Mechatronics Engineering at Chungnam National University in Daejeon, Korea. His research interests are real-time multibody formulation and its application to the automotive systems and military robot systems.     

A Decentralized Approach to Estimate Activity-Based Costs and Near-Optimal Resource Allocation in Flexible Manufacturing Systems

Flexible manufacturing systems (FMSs) can apply the efficiencies of large-scale production to small batch production. The coordination of FMS activities is a complex task; this paper presents a decentralized pricing mechanism that can be used to estimate the activity–based costs and manage the activities of the FMS efficiently. The pricing mechanism described in this paper does not require systemwide information to compute prices; instead, the pricing mechanism samples and uses the demand information at each CNC machine to compute rental prices at that machine. We derive the theoretical formula for rental prices supporting the optimal performance and propose simulation studies to estimate the rental prices for real-time price changes in a decentralized manner. Results from a preliminary simulation study indicate that stable rental prices can be estimated and significant improvements can be realized by using the pricing mechanism.     

A fuzzy expert system to increase accuracy and precision in measurement system analysis

In this paper, we have presented the first proposal to apply measurement system analysis (MSA) in fuzzy environment. Nowadays, because the quality control techniques are applied a lot in manufacturing, research and development environments, many decisions are made in processes and equipment evaluation, control, and improvement. Besides, the philosophy of measurement system analysis (MSA) depends on measurement error which hides true process capability; therefore, it must be implemented prior to any process improvement activities to minimize the measurement errors. Since the capability of each quality system is related to the accuracy of its measurement system, this research develops a novel methodology to increase precision and accuracy of MSA. To do so analyzing measurement systems under fuzziness of indices are investigated to make the environment more realistic. In this article, not only fuzzy measurement system analysis with gauge repeatability and reproducibility (GR&R) index as a triangular fuzzy number is proposed, but a fuzzy measurement system analysis a fuzzy expert system is presented to make more reliable and appropriate decisions. At the end, the applicability of the proposed methodology has been demonstrated within a case study in automotive parts industry to show impact of uncertainty in the reality.