The transfer matrix method for multibody systems is a new method with very high computational speed developed in recent 20 years for studying multibody system dynamics. By combining transfer matrix method for multibody systems, computer graphics, and open-source software, this article puts forward an approach and software MSTMMSim for visualized simulation and design of mechanical system dynamics. The approach includes the following procedures in sequence: design of functional model, design of three-dimensional solid model, design of dynamics model, automated formation of dynamics equations, and software MSTMMSim for visualized simulation and design of mechanical system dynamics. The proposed method and software provide a platform to realize the simulation and design of complex mechanical systems with the following characteristics: (1) automatic deduction of the overall transfer equation, (2) high computational speed, and (3) high visualization and programming of dynamics simulation and design process. The proposed method and software are verified by the practical example of simulation and design of a tank system dynamics using this platform. KeywordsMultibody system dynamics, transfer matrix method for multibody systems, visualized simulation and design, pre-processor, transfer matrix method for multibody system solver, post-processor, software Date

The hysteresis characteristics resulted from piezoelectric actuators (PAs) and the residual vibration in the rapid positioning of a two-dimensional piezo-driven micro-displacement scanning platform (2D-PDMDSP) will greatly affect the positioning accuracy and speed. In this paper, in order to improve the accuracy and speed of the positioning and restrain the residual vibration of 2D-PDMDSP, firstly, Utilizing an online hysteresis observer based on the asymmetrical Bouc-Wen model, the PA with the hysteresis characteristics is feedforward linearized and can be used as a linear actuator; secondly, zero vibration and derivative shaping (ZVDS) technique is used to eliminate the residual vibration of the 2D-PDMDSP; lastly, the robust model reference adaptive (RMRA) control for the 2D-PDMDSP is proposed and explored. The rapid control prototype of the RMRA controller combining the proposed feedforward linearization and ZVDS control for the 2D-PDMDSP with rapid control prototyping technique based on the real-time simulation system is established and experimentally tested, and the corresponding controlled results are compared with those by the PID control method. The experimental results show that the proposed RMRA control method can significantly improve the accuracy and speed of the positioning and restrain the residual vibration of 2D-PDMDSP.

In the future, the tactical edge is far away from the command center, the resources of communication and computing are limited, and the battlefield situation is changing rapidly, which leads to the weak connection and fast changes of network topology in a harsh and complex battlefield environment. Thus, to meet the needs of communication and computing to build a new generation of computing architecture for real-time sharing and service collaboration of tactical edge resources to win the future war, the dispersed computing (DCOMP) seeks a new solution to satisfy the requirements of fast and efficient sensing, transmission, integrating, scheduling, and processing of various information in the tactical edge. Through the research of a traditional computing paradigm of mobile cloud computing (MCC), fog computing (FC), mobile edge computing (MEC), mobile ad hoc network (MANET), etc., it can be found that these computations have difficulty in meeting the high changing and complex battlefield environment and we propose a novel architecture of DCOMP to build a scalable, extensible, and robust decision-making system, to realize powerful and secure communication, computing, storage, and information processing capabilities for the tactical edge. We illustrate the fundamental principles of building a network model, channel allocation, and forwarding control mechanism of the network architecture for DCOMP called DANET and then design a new architecture, programming model, task awareness, and computing scheduling for DCOMP. Finally, we discuss the main requirements and challenges of DCOMP in future wars.

The complex mechanical systems such as high-speed trains, multiple launch rocket system, self-propelled artillery, and industrial robots are becoming increasingly larger in scale and more complicated in structure. Designing these products often requires complex model design, multibody system dynamics calculation, and analysis of large amounts of data repeatedly. In recent 20 years, the transfer matrix method of multibody system has been widely applied in engineering fields and welcomed at home and in abroad for the following features: without global dynamic equations of the system, low orders of involved system matrices, high computational efficiency, and high programming. In order to realize the rapid and visual simulation for complex mechanical system virtual design using transfer matrix method of multibody system, a virtual design software named MSTMMSim is designed and implemented. In the MSTMMSim, the transfer matrix method of multibody system is used as the solver for dynamic modeling and calculation; the Open CASCADE is used for solid geometry modeling. Various auxiliary analytical tools such as curve plot and animation display are provided in the post-processor to analyze and process the simulation results. Two numerical examples are given to verify the validity and accuracy of the software, and a multiple launch rocket system engineering example is given at the end of this article to show that the software provides a powerful platform for complex mechanical systems simulation and virtual design.

In order to accurately model the hysteresis and dynamic characteristics of piezoelectric stack actuators (PSAs), consider that a linear force and a hysteresis force will be generated by piezoelectric wafers under the voltage applied to a PSA, and the total force suffering from creep will result in the forced vibration of the two-degree-of-freedom mass-spring-damper system composed of the equivalent mass, stiffness, and damping of the piezoelectric wafers and the bonding layers. A modified comprehensive model for PSAs is put forward by using a linear function, an asymmetrical Bouc-Wen hysteresis operator, and a creep function to model the linear force, the hysteresis force, and the creep characteristics, respectively. In this way, the effect of the bonding layers on the hysteresis and dynamic characteristics of PSAs can be analyzed via the modified comprehensive model. The experimental results show that the modified comprehensive model for PSAs with the corresponding parameter identification method can accurately portray the hysteresis and dynamic characteristics of PSAs fabricated by different layering/stacking processes. Finally, the theoretical analyzing on utilizing the modified comprehensive model to linearize the hysteresis characteristics and design the dynamic characteristics of PSAs is given.

The piezo-positioning system with high dynamic performance is urgently needed in the field of precision manufacturing and precision instrumentation. The observed rate-dependent hysteresis presents more challenges and difficulties for accurately modeling the response behavior of the piezoelectric stack actuators over the last several decades. Our previous research shows that the rate-dependent characteristics may be caused by the dynamic characteristics of the power amplifier. In order to achieve the high-bandwidth and high-speed motion control accuracy, we propose an open-loop compensation control method of a piezo-positioning mechanism based on a composite electromechanical dynamic model. The dynamic model can describe the dynamic characteristics of the power amplifier, the inverse piezoelectric effect and the dynamics of the mechanism. Experimental results show that the proposed control method can achieve precise motion control of the piezo-positioning mechanism within 1–800 Hz bandwidth.

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