International Journal of Engineering Systems Modelling and Simulation (9 papers in press)
Redesign and Evaluation of an Equation-Based Model Reduction Method in OpenModelica
by Fatemeh Davoudi, Oliver Lenord, Niklas Worschech, Umut Durak, Sven Hartmann
Abstract: Even in times of a continuously growing computational power and progressing miniaturization of computers and control devices, the demand for model reduction techniques persists. This is due to the intrinsic conflict between precision and performance of simulations in general. The trade-off between precision and performance depends on the purpose of the simulation as well as the runtime requirements of the target device. Detailed models of physical systems used in an early stage of the system design process typically result in rather complex dynamic models. In later stages of the design process, when the design space has been narrowed down to a concrete design, it is often desirable to replace these detailed models by simpler ones. The reduced models are expected to run multitudes faster while preserving important properties of the original model required for control design and validation purposes. Equation-based model order reduction is a promising approach to serve the needs. This paper presents a redesigned implementation of a equation-based model reduction method in the OpenModelica compiler. For evaluation purposes the reduction method is applied to a simple sample model (two mass spring damper). The performance of the generated reduced model and the cost of the reduction process are evaluated. The reduced model generated by the reduction algorithm is compared with the results of a theoretically derived reduced model. In the conclusions deficits of the current implementation are discussed. Proposals for further improvements of the implementation and enhancements of the methodology for extended control design use cases are given in the outlook.
Keywords: model reduction; parametric model reduction; non-linear model reduction; proper model generation; Modelica; OpenModelica; residual ranking.
Finite element analysis of the vertical roller mill based on ANSYS Workbench
by Weihua Wei, Yuantong Li, Hongwei Zhu, Peng Jin
Abstract: By using of element analysis software ANSYS Workbench, the static analysis of lower rocker arm and column, and the modal analysis of column are carried out. The three-dimensional models of lower rocker arm and column were imported into the ANSYS Workbench for meshing. The loads and constraints were imposed on the meshed model to solve for the stress and deformation. The contour plots of stress and the total deformation of the lower rocker arm and column indicate that the structure meets the design requirements in strength and stiffness, which verifies the reliability of the structure. Through the modal analysis of column under free and constrained states, the first eight natural frequencies and vibration modals under free and constrained states are obtained, which can intuitively reflect the dynamic characteristics of the column itself, help to avoid structural resonances in engineering applications, and provide a theoretical basis for the optimization design and fault detection of the column.
Keywords: vertical roller mill; lower rocker arm; column; static analysis; modal analysis; ANSYS Workbench.
Three-dimensional Image Reconstruction Method for Human maxillofacial defect images Based on Block Sample Feature Matching
by Lingling Cui
Abstract: In traditional methods, template matching of human face image sample and edge contour segmentation are ignored, and the application is susceptible to the robustness of skin color features and pose changes, resulting in poor accurate three-dimensional reconstruction and recognition of human maxillofacial defect images. Therefore a three-dimensional image reconstruction method for human maxillofacial defect images based on block sample feature matching is proposed. A feature matching template of human maxillofacial images is constructed, and template matching and three-dimensional edge contour segmentation are performed to the sample images through the blocking technique. The simulation results show that this method has good feature detection and detection ability in three-dimensional reconstruction of human maxillofacial defect images and can provide high accuracy in three-dimensional reconstruction.
Keywords: Human maxillofacial defect; image; three-dimensional reconstruction; corner detection.
Stress and Deformation Analysis of A Reinforced Continuous Girder Bridge
by Dongyu Ji, Xiaofen Li
Abstract: In order to study the stress and deformation of reinforced concrete continuous beam bridge, numerical simulation analysis of reinforced concrete continuous girder bridge is carried by finite element method. The results show that, the tensile stress of the bridge deck generally appears in the lower part of the span and the upper part of the support, while the compressive stress generally appears in the upper part of the span and the lower part of the support; The displacement of bridge superstructure is larger than that of substructure and soil layer, the vertical deformation of the bridge is mainly caused by the gravity of the bridge. The research results provide some references for the design and construction of continuous girder bridge.
Keywords: Box girder; Continuous girder bridge; Numerical simulation; Calculation model; Stress distribution.
Detection of spindle thermal state accuracy of vertical CNC machine tool
by Jianchen Wang, Xiaolei Deng
Abstract: In order to test the thermal accuracy of spindle system of mining vertical CNC machine tools, to enhance the error compensation ability of the system accuracy detection model and improve the machine tool processing accuracy, a test platform for thermal accuracy of spindle system was constructed. Five-point method was used to test the thermal accuracy of spindle system, and thermocouple and infrared thermal imager were used to measure the spindle system. Temperature change data at key points of temperature rise are used to identify temperature sensitive measurement points by grey comprehensive correlation analysis method. A thermal accuracy prediction model based on cooperative quantum particle algorithm is constructed. The prediction effect of the model is evaluated. The experimental results show that the thermal accuracy detection model has high detection accuracy.
Keywords: CNC machine tools; spindle system; detection of thermal state accuracy; model.
Experimental evaluation of new navigator of mobile robot using fuzzy Q-learning
by Fadhila Lachekhab, Mohamed Tadjine, Mohamed Kesraoui
Abstract: In this paper, we propose an approach of fusing the fuzzy control actions of the obstacle avoidance and goal-seeking which utilises fuzzy logic and reinforcement learning for navigation of a mobile robot in unknown environments. The proposed reactive navigator consists of three modules: move to goal, obstacle avoidance, and fuzzy behaviour supervisor. The selection of the actions available in each fuzzy rule is learned through reinforcement learning (Q-learning algorithm). A new and powerful method is used to construct automatically these rules. The experiments carried out on the Pioneer 2P mobile robot have shown that the navigator is able to perform a successful navigation task in various unknown environments with smooth action and exceptionally good robustness.
Keywords: fuzzy Q-learning; FQL; fuzzy inference system; fusing behaviours; mobile robot; Pioneer 2P; unknown environment; temporal difference; reinforcement learning.
Networked multi pipeline pressure synchronous coordinated predictive control based on the model free adaptive method
by You Wu, Guo-Ping Liu
Abstract: In order to achieve the rapid and accurate synchronous coordination of multi pipeline pressure systems using networked control system theory, an adjacent cross-coupling structure is adopted to improve the synchronisation performance. Considering the possible limitations of network communication, a networked predictive control algorithm based on model free adaptive control is proposed to compensate the delay caused by network. The above two strategies are combined to form the networked multi pipeline pressure synchronous coordination predictive control systems. The simulation experiments of synchronous coordinated control of three pipeline pressure systems are carried out on Simulink platform. The simulation results show that the proposed control scheme can compensate the network delay, and improve the dynamic and synchronous performance. The effectiveness of the control scheme is verified.
Keywords: networked control system; NCS; pressure control; model free adaptive control; MFAC; synchronous coordination; data-based predictive control.
Dynamical and steady state performance analysis of DC series motor and induction motor powered by an autonomous PV generator using MPPT
by Mohammed Ibrahim Abuashour, Tha'er Omar Sweidan
Abstract: This paper presents the dynamical and steady state analysis of DC series motor and induction motor fed by photovoltaic generator at different solar irradiance levels. The maximum power point of current/voltage (I/V) characteristic of the PV generator is achieved for different solar intensities, by utilising an open voltage method. The nonlinear operational behaviour of (I/V) characteristics of the PV generator at various solar intensities and the magnetisation curve of the ferromagnetic material of the DC series motor are modelled by high order polynomial mathematical expressions. The dynamical and steady state analysis of the DC series motor and induction motor fed by PV generator at different solar intensity has been tested and investigated; also the dynamical and steady state analysis of DC series motor and induction motor is also farther investigated and studied as a step change in solar intensity levels with fixed loads torque for both motors. All numerical simulations are executed using MATLAB software.
Keywords: induction motor; DC series motor; maximum power point tracking; MPPT; PV generator; dynamical analysis; steady state analysis.
Body scanning oriented 3D object modelling method based on multi-view depth camera
by Ping Xu, Fengjun Hu, Ji Gao, Jianwei Lin, Huafeng Chen
Abstract: To implement the human body scanning process, in this paper, we propose a novel 3D object modelling method based on multi-view depth camera. The main innovations of this paper lie in that we model 3D object via fusing several depth images captured from depth cameras. Different from the 3D scanner-based 3D object modelling, this proposed method is much cheaper and easier to operate. To construct the multiple depth camera system, a camera is located at the centre point, and others are positioned at four directions with the same intervals. Afterwards, a cost function is defined to fuse the multiple views of depth images based on depth map of the surface points. Experimental results demonstrate that the proposed method can effectively 3D scan the human body, and our method is slightly inferior to 3D scanner. However, the proposed depth camera based method is much cheaper and easier to master.
Keywords: body scanning; 3D object modelling; depth camera; Kinect; cost function.