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Chongqing, China

Gao F.,Chongqing University | Li X.,Chongqing University | Li Y.,Changan Automobile Co.
Proceedings of the World Congress on Intelligent Control and Automation (WCICA)

In practice, models always have uncertainties due to unavoidable factors. A multiple model robust control method for linear multi-input and multi-output plants with large parametric uncertainty is presented in this paper. The candidate controllers are designed by H-inf control method and by analyzing how model uncertainty influences the error of estimated output, a new estimator and switching index, which can evaluate the system norm of model uncertainty, are proposed. By this way, the control system can be equivalent to a switching system with small uncertainty whose system norm is limited. The robust stability of the closed control system is studied by using small gain theorem. And furthermore simulations have been done on a second order inertial system to validate its effectiveness of this new multiple model robust control method. © 2014 IEEE. Source

Lu S.,Chongqing University | Li Y.,Chongqing University | Dong Y.,Changan Automobile Co.
Applied Mechanics and Materials

This paper presents a new correlated methodology for engineers to develop a specific vehicle-Unimog associated with a unique structure of movement transmission. A complicated multi-body dynamic model which includes the front/rear axle suspension with thrust tube and coil springs, the steering system, tire and road exciting model is established based on the virtual reality (VR) technology. The topology and kinematics relation of the whole system are analyzed firstly, then the proper constrain pairs are applied among them to satisfy the amazing flexibility and ride comfort of the real vehicle. To more accurately model the real system, some key parameters are acquired by the way of experiment and prediction, respectively. And a triangle function method which combined the inverse Fourier and discrete random producer is proposed based on the standard PSD (power spectrum density). Finally, the ride performance has been evaluated on the random road by simulation and field test. The results show that the applied constraint of the model is correct and the kinematics relation matches the actual condition well. The consistency trends both in time and frequency domain for virtual and field test result show that the established model is effective. © 2011 Trans Tech Publications. Source

Lan L.-P.,Beijing Institute of Technology | Xiang J.-H.,Beijing Institute of Technology | He L.-G.,Changan Automobile Co.
Neiranji Xuebao/Transactions of CSICE (Chinese Society for Internal Combustion Engines)

For effectively suppressing seal failure caused by deformation of cylinder liner in high power diesel engine, the out-of-roundness and Fourier spectrum analysis of the cross section of cylinder liner inner surface were applied as liner deformation evaluation indexs. The cylinder liner deformation characteristics were analyzed under the pre-tightening condition of a composite model with cylinder, cylinder head, cylinder liner. The influence laws of pre-tightening force of head bolts, sink hole depth of head bolts and distribution locations of head bolts on cylinder liner deformation have been studied and compared with test results. The results show that: under the pre-tightening condition, the cylinder liner presents elliptical deformation at the upper cross-sections and small deformation at the lower position; with the increase of bolt pre-tightening force, whole cylinder liner deformation increases; and then, when the depth of bolt sink hole increases, the second order Fourier deformation of cylinder liner increases, the fourth order decreases;moreover, the increase of the angle between the line of diagonal bolts and the center line of inlet and outlet could reduce the deformation of cylinder liner significantly. © 2015, Chinese Society for Internal Combustion Engines. All right reserved. Source

The assembly effect of automotive exterior parts directly affects the automobile modeling design, and the gap and flush of automotive exterior parts are essential to evaluate assembly effect of automotive exterior parts. In the assembly relation of the machine, the assembly dimensional chain consists of relevant parts size or mutual position relation. The gap and flush of automotive exterior parts can be considered as a closing link of assembly dimensional chain, while the size and position relation of parts do influence the gap and flush, that should be understood as component link of assembly link. According to the basic principle of the mathematical statistics, the assembly dimensional chain should be calculated by statistical tolerance formula. In the four parameters, there are four different optimizing methods of tolerance allocation when three of them are stable. The analysis of assembly dimensional chain of automotive exterior parts should not be adopted into earlier designing stage, but also into later producing stage. © Springer-Verlag Berlin Heidelberg 2015. Source

Kuti O.A.,Hiroshima University | Kuti O.A.,Federal University of Technology Akurre | Zhu J.,Hiroshima University | Nishida K.,Hiroshima University | And 2 more authors.

The influence of injection pressure up to ultra-high value of 300 MPa, nozzle hole diameters of 0.16 and 0.08 mm and fuel properties such as boiling point, cetane number and oxygen content on spray, ignition and combustion characteristics of biodiesel fuel in diesel engine were investigated. Biodiesel from palm oil source (BDF) and for comparison the JIS #2 diesel fuel were utilized. The Mie-scattering technique was used for characterizing the evaporating spray formation processes while the OH chemiluminescence technique was used to determine the ignition and the lift-off length of the combusting flame. Furthermore, the two color pyrometry was applied to study the soot formation processes. The results obtained indicated that due to higher boiling point, the BDF produced longer liquid phase length as compared to diesel. It was observed that the ignition region was larger for the 0.16 mm nozzle as compared to the 0.08 mm. Due to the enhanced mixing processes, ignition delay decreased as the injection pressure increased from 100 to 300 MPa respectively and also by reducing the nozzle hole diameter to 0.08 mm. Higher cetane number and oxygen content of the BDF facilitated shorter ignition delay as compared to diesel. The percentage stoichiometry air entrained increased by decreasing the nozzle hole diameter. The BDF flame produced shorter lift-off length and lower percentage stoichiometry air. Under higher injection pressures and decreasing nozzle diameter, the BDF produced less soot as compared to diesel. The fuel oxygen content in the biodiesel fuel played a greater role in the soot formation processes. © 2010 Elsevier Ltd. All rights reserved. Source

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