Dynamic Simulations of Nonlinear Multi-Domain Systems Based on Genetic Programming and Bond Graphs

A dynamic simulation method for non-linear systems based on genetic programming （GP） and bond graphs （BG） was developed to improve the design of nonlinear multi-domain energy conversion systems. The genetic operators enable the embryo bond graph to evolve towards the target graph according to the fitness function. Better simulation requires analysis of the optimization of the eigenvalue and the filter circuit evolution. The open topological design and optimized convergence for the operation, but also the design of nonlinear multi-domain systems. space search ability of this method not only gives a more reduces the generation time for the new circuit graph for

Global Dynamic Modeling of Electro-Hydraulic 3-UPS/S Parallel Stabilized Platform by Bond Graph

Dynamic modeling of a parallel manipulator（PM） is an important issue. A complete PM system is actually composed of multiple physical domains. As PMs are widely used in various fields, the importance of modeling the global dynamic model of the PM system becomes increasingly prominent. Currently there lacks further research in global dynamic modeling. A unified modeling approach for the multi-energy domains PM system is proposed based on bond graph and a global dynamic model of the 3-UPS/S parallel stabilized platform involving mechanical and electrical-hydraulic elements is built. Firstly, the screw bond graph theory is improved based on the screw theory, the modular joint model is modeled and the normalized dynamic model of the mechanism is established. Secondly, combined with the electro-hydraulic servo system model built by traditional bond graph, the global dynamic model of the system is obtained, and then the motion, force and power of any element can be obtained directly. Lastly, the experiments and simulations of the driving forces, pressure and flow are performed, and the results show that, the theoretical calculation results of the driving forces are in accord with the experimental ones, and the pressure and flow of the first limb and the third limb are symmetry with each other. The results are reasonable and verify the correctness and effectiveness of the model and the method. The proposed dynamic modeling method provides a reference for modeling of other multi-energy domains system which contains complex PM.

基于Bond Graph的电机驱动转子系统振动特性研究

电机驱动的转子系统是工业领域中很常见的机电耦合系统,其动力学行为及振动特性是影响机电系统安全运行的重要因素。Bond Graph作为一种基于功率流的建模方法,对复杂的耦合系统动力学建模具有独特的优势。基于Bond Graph建立了电机驱动转子系统的动力学分析模型,以该模型为基础仿真分析了机电耦合系统的动力学特性。结合转子试验台,研究了电机工况变化及不对中故障情况下,转子系统的振动特性变化规律。仿真结果与试验台实验结果相吻合,验证了该Bond Graph模型的准确性和有效性。

An Approach to Representation for Principle Scheme Design

One of the open issues in principle scheme design of mechanical systems is principle representation, which not only outlines the physical principles, but also facilitates the design synthesis. An energy-based approach to represent principle scheme design is proposed. Firstly, an energy interaction model of mechanical systems is established and an intermediate model is derived, in which principle scheme design is transformed into solving the energy functions of system. Then the energy functions are modeled with the language of bond graphs, and principle representation for components is presented. Finally, characteristics of the developed representation approach are analyzed and a design example of gate drive system is given to demonstrate this approach.

Model-Based Fault Tolerant Control for Hybrid Dynamic Systems with Sensor Faults

A model-based fault tolerant control approach for hybrid linear dynamic systems is proposed in this paper. The proposed method, taking advantage of reliable control, can maintain the performance of the faulty system during the time delay of fault detection and diagnosis (FDD) and fault accommodation (FA), which can be regarded as the first line of defence against sensor faults. Simulation results of a three-tank system with sensor fault are given to show the efficiency of the method.

Modeling and Simulation of Hydraulic Hammer for Sleeve Valve

Hydraulic hammer is commonly used hydraulic equipment in engineering work. The characteristics, high acceleration, high frequency and inertial working pressure, make it greatly different from the working conditions of conventional hydraulic equipment, while hydraulic hammer for sleeve type is also not the same as other hydraulic hammers in structure, efficiency and working performance. Based on the principle of hydraulic hammer for sleeve type, the mathematical model of hydraulic hammer for sleeve type was set with various conditions in the reciprocating movement of piston. In addition, more detailed sketch model can be easily built with the mathematical model in multi-domain system analysis software, AMESim. The simulation system of breaker built based on the principle of power bond graph structures in AMESim system is considered comprehensively to achieve its functions and characteristics, which can quickly realize the calculation of main simulation parameters for impactor. The calculated parameters can be proved to be biased with the test prototype. So these parameters must be optimized by Design Exploration to find the appropriate parameters.

EXPERIMENTAL STUDY ON INFLUENCE OF SUPPLIED PRESSURE FLUCTUATION ON OUTPUT ARACTERISTIC OF PRESSURE CONTROL SYSTEM OF ROLLING MILL

The infulence of supplied pressure fluctuation on output accuracy for the electro hydraulic pressure control system of the rolling mill is discussed.Based on the bond graph theory and experimental study,the relationship between the variation of system output pressure and the supplied pressure fluctuation and the influence of the system bandwidth on system output pressure are provided.A theoretical base for determining the allowable fluctuation range of pressure and accurate design of constant pressure source system is obtained.

Modelling and simulation of flight control electromechanical actuators with special focus on model architecting, multidisciplinary effects and power flows

In the aerospace field, electromechanical actuators are increasingly being implemented in place of conventional hydraulic actuators. For safety-critical embedded actuation applications like flight controls, the use of electromechanical actuators introduces specific issues related to thermal balance, reflected inertia, parasitic motion due to compliance and response to failure. Unfortunately, the physical effects governing the actuator behaviour are multidisciplinary, coupled and nonlinear. Although numerous multi-domain and system-level simulation packages are now available on the market, these effects are rarely addressed as a whole because of a lack of scientific approaches for model architecting, multi-purpose incremental modelling and judicious model implementation. In this publication, virtual prototyping of electromechanical actuators is addressed using the Bond-Graph formalism. New approaches are proposed to enable incremental modelling,thermal balance analysis, response to free-run or jamming faults, impact of compliance on parasitic motion, and influence of temperature. A special focus is placed on friction and compliance of the mechanical transmission with fault injection and temperature dependence. Aileron actuation is used to highlight the proposals for control design, energy consumption and thermal analysis, power network pollution analysis and fault response.

Multi-level virtual prototyping of electromechanical actuation system for more electric aircraft

Electromechanical actuators（EMAs） are becoming increasingly attractive in the field of more electric aircraft because of their outstanding benefits, which include reduced fuel burn and maintenance cost, enhanced system flexibility, and improved management of fault detection and isolation. However, electromechanical actuation raises specific issues when being used for safetycritical aerospace applications like flight controls： huge reflected inertia to load, jamming-type failure, and increase of backlash with service due to wear and local dissipation of heat losses for thermal balance. This study proposes an incremental approach for virtual prototyping of EMAs. It is driven by a model-based system engineering process in order to enable simulation-aided design.Best practices supported by Bond graph formalism are suggested to develop a model＇s structure efficiently and to make the model ready for use（or extension） by addressing the above mentioned issues. Physical effects are progressively introduced, and the realism of lumped-parameter models is increased step-by-step. In particular, multi-level component models are architected to ensure continuity between engineering activities. The models are implemented in the AMESim simulation environment, and simulation responses are given to illustrate how they can be used for preliminary sizing, control design, thermal balance verification, and faults to failure analysis. The proposed best practices intend to provide engineers with fast, reusable, and efficient means to assess performance virtually and enhance maturity, performance, and robustness.

Structural Topology and Dynamic Response Analysis of an Electric Torque Vectoring Drive-Axle for Electric Vehicles

In-wheel motor-drive electric vehicles have the advantage of independently controllable wheel torque and the disadvantages of unsprung mass rise and power restriction.To address the disadvantages,a centralized layout electric torque vectoring drive-axle system(E-TVDS)with dual motors is proposed,which can realize arbitrary distribution of driving torque between the left and right wheels.First,the speed and torque distribution principle of E-TVDS based on velocity diagram are analyzed,and a virtual prototype of the whole vehicle with basic gear ratio relation model of the E-TVDS is built for simulation to verify the theoretical results and the basic effect of E-TVDS on the steering performance of the vehicle.Second,the charac-teristics of 36 types of the novel E-TVDS topology structure are compared and analyzed,and the optimal structure scheme is selected.Third,the accurate multiple degrees of freedom dynamic model for the optimal structure is established by using the bond graph method,and its dynamic response characteristics are analyzed.The results show that the vehicle equipped with the proposed E-TVDS can distribute the driving torque with the almost identical amount but opposite sign between the left and right wheels in any direction,and varying amount according to different chassis dynamics control requirements,and the torque response performance is great with little delay and overshoot.The function and dynamic response of the proposed E-TVDS show that it has potential application value for various performance improvements of electric vehicles.