Co-simulation Model Research Articles

Tracking Control for Robotic Manipulators using Fractional Order Controllers with Computed Torque Control

This paper presents the tracking tasks control for a robotic manipulator employing a fractional order PID controller with the computed torque control strategy. The proposed control strategy is contrasted with an integer order PID controller with the computed torque control strategy. The robotic system is a two degree of freedom manipulator simulated using a MSCADAMS/MATLAB cosimulation model. The manipulator dynamic model is identified employing the recursive least squares algorithm. The fractional order PID controller is tuned using optimization techniques. Controllers robustness is evaluated against the presence of external disturbances in the joints torques, random noise in the feedback loop and payload variations. Obtained results show that the fractional order PID controller with the computed torque control strategy has better performance and robust stability against the presence of the analyzed external disturbances for tracking tasks.

Electro-hydraulic velocity and position control based on independent metering valve control in mobile construction equipment

Abstract Independent metering valve control system can overcome the shortcomings of the traditional four-side linkage valve controlled system, such as poor controllability and large energy consumption, especially under the overrunning load condition. Current researches mainly focus on the velocity, pressure and energy consumption characteristics of the hydraulic system. However, with the intelligent development of mobile machinery and the continuous improvement of work quality requirements, each actuator should not only meet the velocity and output force requirements, but also achieve high positioning accuracy. Therefore, according to the independent metering valve control system and pump-valve hybrid control principle, a velocity and position combined control strategy based on mode switching is proposed to control the boom and arm of hydraulic excavator. Then, a mechanical-hydraulic co-simulation model including the whole hydraulic excavator is established to verify the strategy, predict control characteristics and determine the controller parameters. Furthermore, a test prototype based on the above principle is established, and the boom and arm operating characteristics with the proposed strategy are tested and analyzed. The results show that the hydraulic cylinders can move smoothly along the expected trajectory under the premise of low energy consumption. The operate velocity fluctuation is small and the positioning error to the target position is about 1 mm. Due to the boom cylinder and arm cylinder in the research are separately typical two and four quadrants working actuators, the research work has universal significance to smooth, high-precision and low energy consumption automation operation of various types of mobile machineries.

Real-Time Implementation of Parallel Architecture Based Noise Minimization from Speech Signals on FPGA

In recent years, the real time hardware implementation of LMS based adaptive noise cancellation on FPGA is becoming popular. There are several works reported in this area in the literature. However, NLMS based implementation of adaptive noise cancellation on FPGA using Xilinx System Generator (XSG) is not reported. This paper explores the various forms of parallel architecture based on NLMS algorithm and its hardware implementation on FPGA using XSG for noise minimization from speech signals. In total, the direct form, binary tree direct form and transposed form of parallel architecture of normalized least mean square (NLMS), delayed normalized least mean square and retimed delayed normalized least mean square algorithms are implemented on FPGA using hardware co-simulation model. The performance parameters (SNR and MSE) of these algorithms are analyzed for the adaptive noise cancellation system and the comparison is made with parallel architectures of least mean square (LMS), delayed least mean square, and retimed delayed least mean square algorithms respectively. The hardware utilization of all the said algorithms are also analyzed and compared. The result shows that NLMS based implementations outperform than that of LMS for all forms of parallel architecture for the given parameters with negligence increase in device utility. The binary tree direct form of retimed delayed NLMS achieves the maximum SNR improvement (39.83 dB) in comparison to other NLMS variants at the cost of optimum resource utilization.

Fractional order PID for tracking control of a parallel robotic manipulator type delta

This paper presents the tracking control for a robotic manipulator type delta employing fractional order PID controllers with computed torque control strategy. It is contrasted with an integer order PID controller with computed torque control strategy. The mechanical structure, kinematics and dynamic models of the delta robot are descripted. A SOLIDWORKS/MSC-ADAMS/MATLAB cosimulation model of the delta robot is built and employed for the stages of identification, design, and validation of control strategies. Identification of the dynamic model of the robot is performed using the least squares algorithm. A linearized model of the robotic system is obtained employing the computed torque control strategy resulting in a decoupled double integrating system. From the linearized model of the delta robot, fractional order PID and integer order PID controllers are designed, analyzing the dynamical behavior for many evaluation trajectories. Controllers robustness is evaluated against external disturbances employing performance indexes for the joint and spatial error, applied torque in the joints and trajectory tracking. Results show that fractional order PID with the computed torque control strategy has a robust performance and active disturbance rejection when it is applied to parallel robotic manipulators on tracking tasks.

Analyzing horizontal and vertical urban expansions in three East Asian megacities with the SS-coMCRF model

A recently proposed method based on the spectral similarity-enhanced Markov chain random field cosimulation (SS-coMCRF) model has provided a practical approach for estimating both horizontal and vertical urban expansion of megacities using Landsat images. Estimating vertical urban growth – the area change of mid-rise or taller buildings (MTBs) – makes it possible to gain some new insights into the urban expansion of megacities. This study makes use of the new approach to examine the horizontal and vertical urban expansion of three capital megacities (Beijing, Seoul, and Tokyo) in East Asia during the late 1980s to the mid-2010s. In contrast to previous studies that only assessed horizontal urban growth, which usually showed almost no increase in urban area in some highly developed cities, this study indicates some different findings: (1) Both horizontal and vertical urban expansion had been happening in the three megacities during the studied period, especially with respect to vertical urban expansion. During the studied period there were 20.7 km2, 11.3 km2, and 6.8 km2 MTB area increases in Beijing, Seoul, and Tokyo, respectively. (2) Different cities showed some differences in growth patterns, mainly because they were at different urban development stages and impacted by different local situations in terms of geography, population, and development policies. (3) A similarity is that the three megacities all tended to horizontally expand initially and then grow vertically in the already developed areas. This study may provide a useful new perspective on the urban expansion of megacities.

Connectivity-based optimization of vehicle route and speed for improved fuel economy

Traditionally, vehicle route planning problem focuses on route optimization based on traffic data and surrounding environment. This paper proposes a novel extended vehicle route planning problem, called vehicle macroscopic motion planning (VMMP) problem, to optimize vehicle route and speed simultaneously using both traffic data and vehicle characteristics to improve fuel economy for a given expected trip time. The required traffic data and neighbouring vehicle dynamic parameters can be collected through the vehicle connectivity (e.g. vehicle-to-vehicle, vehicle-to-infrastructure, vehicle-to-cloud, etc.) developed rapidly in recent years. A genetic algorithm based co-optimization method, along with an adaptive real-time optimization strategy, is proposed to solve the proposed VMMP problem. It is able to provide the fuel economic route and reference speed for drivers or automated vehicles to improve the vehicle fuel economy. A co-simulation model, combining a traffic model based on SUMO (Simulation of Urban MObility) with a Simulink powertrain model, is developed to validate the proposed VMMP method. Four simulation studies, based on a real traffic network, are conducted for validating the proposed VMMP: (1) ideal traffic environment without traffic light and jam for studying the fuel economy improvement, (2) traffic environment with traffic light for validating the proposed traffic light penalty model, (3) traffic environment with traffic light and jam for validating the proposed adaptive real-time optimization strategy, and (4) investigating the effect of different powertrain platforms to fuel economy using two different vehicle platforms. Simulation results show that the proposed VMMP method is able to improve vehicle fuel economy significantly. For instance, comparing with the fastest route, the fuel economy using the proposed VMMP method is improved by up to 15%.

ANSYS‐MATLAB co‐simulation of mucus flow distribution and clearance effectiveness of a new simulated cough device

Coughing is an irritable reaction that protects the respiratory system from infection and improves mucus clearance. However, for the patients who cannot cough autonomously, an assisted cough device is essential for mucus clearance. Considering the low efficiency of current assisted cough devices, a new simulated cough device based on the pneumatic system is proposed in this paper. Given the uncertainty of airflow rates necessary to clear mucus from airways, the computational fluid dynamics Eulerian wall film model and cough efficiency (CE) were used in this study to simulate the cough process and evaluate cough effectiveness. The Ansys-Matlab co-simulation model was set up and verified through experimental studies using Newtonian fluids. Next, model simulations were performed using non-Newtonian fluids, and peak cough flow (PCF) and PCF duration time were analyzed to determine their influence on mucus clearance. CE growth rate (λ) was calculated to reflect the CE variation trend. From the numerical simulation results, we find that CE rises as PCF increases while the growth rate trends to slow as PCF increases; when PCF changes from 60 to 360L/min, CE changes from 3.2% to 51.5% which is approximately 16 times the initial value. Meanwhile, keeping a long PCF duration time could greatly improve CE under the same cough expired volume and PCF. The results indicated that increasing the PCF and PCF duration time can improve the efficiency of mucus clearance. This paper provides a new approach and a research direction for control strategy in simulated cough devices for airway mucus clearance.

Improving Object-Based Land Use/Cover Classification from Medium Resolution Imagery by Markov Chain Geostatistical Post-Classification

Land use/land cover maps derived from remotely sensed imagery are often insufficient in quality for some quantitative application purposes due to a variety of reasons such as spectral confusion. Although object-based classification has some advantages over pixel-based classification in identifying relatively homogeneous land use/cover areas from medium resolution remotely sensed images, the classification accuracy is usually still relatively low. In this study, we aimed to test whether the recently proposed Markov chain random field (MCRF) post-classification method, that is, the spectral similarity-enhanced MCRF co-simulation (SS-coMCRF) model, can effectively improve object-based land use/cover classifications on different landscapes. Four study areas (Cixi, Yinchuan and Maanshan in China and Hartford in USA) with different landscapes and classification schemes were chosen for case studies. Expert-interpreted sample data (0.087% to 0.258% of total pixels) were obtained for each study area from the original Landsat images used in object-based pre-classification and other sources (e.g., Google satellite imagery). Post-classification results showed that the overall classification accuracies of the four cases were obviously improved over the corresponding pre-classification results by 14.1% for Cixi, 5% for Yinchuan, 11.8% for Maanshan and 5.6% for Hartford, respectively. At the meantime, SS-coMCRF also reduced the noise and minor patches contained in pre-classifications. This means that the Markov chain geostatistical post-classification method is capable of improving the accuracy and quality of object-based land use/cover classification from medium resolution remotely sensed imagery in various landscape situations.

An Electromechanical Co-Simulation Model Based on Lumped Parameter Model of Ball Screw Feed Drive System

The continuous search for efficiency put forward higher requests to the machine tool for high speed and high acceleration, which makes the large-size and lightweight-designed feed drive system more likely to produce vibration during high-speed and high-acceleration feed operation. Ball screw feed system is the most widely used linear drive system in the field of industrial automation. Electromechanical Co-Simulation for ball screw feed drive dynamics is an important technique for solving vibration problems occurs in the feed motion. In view of the shortcomings of the current dynamic simulation model in the study of vibration of ball screw feed drive system, taking a ball screw feed drive system test bench as an example, an electromechanical co-simulation model based on the lumped parameter model of ball screw feed drive system was built up in this paper. Firstly, based on the axial and rotation vibration integrated dynamic modeling method of ball screws, the lumped parameter model of ball screw feed system was established. Secondly, through the integration of the simulation model of semi-closed-loop cascade control system and the lumped parameter model of ball screw feed drive system, an electromechanical co-simulation model was built up. Simulation result shows that, the co-simulation model of ball screw feed drive system can predict the vibration occurs in the feed operation caused by the servo controller, ball screw feed system or the coupling between them.

Study on dynamic characteristics and control algorithm design for fuel metering valve of high-pressure pump

High rail pressure and multiple injections are crucial to improve diesel engine performance in terms of fuel efficiency and exhaust emission. As a drawback, rail pressure oscillations and complex pressure-wave propagation phenomena have impact on the control accuracy and response speed. Fuel metering valve, installed on the inlet of high-pressure pump, is the main mechanical actuator to adjust the rail pressure value. In this paper, the co-simulation model was established to investigate the dynamic process which is divided into three phases. The motion dead zones of the valve member and spring preload are the main factors for non-linearity working zone of the fuel metering valve. Therefore, the corresponding segmented control algorithm is designed to adjust the rail pressure based on the fuel flow rate and ideally realize synchronization of the control signals and rail pressure response.

Comparison of RFIC PA Die and Laminate Co-Simulation Methods

Package (such as LGA, MCM etc.) with main circuits on Die(s) situated on a substrate and with OMN in the substrate laminate is one of the most popular design styles for RFIC PAs in recent times. In practical design, the overall circuit of the RFIC PA is often designed using ADS Schematic simulation tool. The main circuit is then layout for Die design, and the OMN circuit is layout for laminate design. As the actual parasitics associated with the real RF circuits with high packing dense have significant effects on the RFIC performance, the traditional closed-form circuit models may be no longer valid, and co-simulations of the Die circuit or Die layout EM model and the laminate layout EM model are often considered in order to improve simulation accuracy. There are some generally considered co-simulation methods in practical design, such as Die circuit + Laminate Momentum, Die circuit +Laminate HFSS, Die layout Momentum +Laminate Momentum, Die layout Momentum +Laminate HFSS, Die layout +Laminate ADS Nested Technology, etc. Design engineers might be confused about which co-simulation methods should take for RFIC PA design and development. This paper reviews, compares and discusses the above co-simulation methods in the aspects of algorithms of the simulators, co-simulation modeling method, complexity to build model, run time, and the difference between simulation and measurement results by giving an example of a self-developed RFIC PA operating at 2GHz. It endeavors to draw helpful conclusions for simulation experiences in practical RFIC PA design, and a co-simulation method with Die layout Momentum EM model +Laminate HFSS EM model is recommended based on the software versions used in this work.

Optimization of CVT Efficiency Based on Clamping Force Control

In order to improve the transmission efficiency of CVT under various driving conditions, this paper proposes an integrated control strategy for optimization of clamping force in pulley. The strategy is based on driving conditions identification and slip trend observer. A Simulink-AMESim co-simulation model is established. Simulation conditions include the acceleration conditions, uphill road conditions, and urban + suburban circle conditions, simulation results show that the new strategy can optimize the transmission efficiency of CVT and therefore increase the fuel efficiency of the vehicle.

Design and analysis of doubly salient permanent magnet dual-mechanical port motor for offshore ships

To meet the requirements of the energy power transmission of the hybrid propulsion system, this paper proposes a new type of the doubly salient permanent magnet dual-mechanical port motor. The structure, electromagnetic properties and temperature field analysis are investigated by means of the finite element analysis method. Besides, it studies the output characteristic by establishing a co-simulation model based on the field-circuit coupled method. The simulation results prove that the motor has inherited the advantages of the doubly salient permanent magnet motor, has high reliability and high power density. Meanwhile, the dual-mechanical port can realize the synthesis and distribution of the motor’s energy flow under different operating conditions.

Multi-Phase Modular Drive System: A Case Study in Electrical Aircraft Applications

In this article, an advanced multiphase modular power drive prototype is developed for More Electric Aircraft (MEA). The proposed drive is designed to supply a multi-phase permanent magnet (PM) motor rating 120 kW with 24 slots and 11 pole pairs. The power converter of the drive system is based on Silicon Carbide Metal Oxide Semiconductor Field-Effect Transistor (SiC MOSFET) technology to operate at high voltage, high frequency and low reverse recovery current. Firstly, an experimental characterization test is performed for the selected SiC power module in harsh conditions to evaluate the switching energy losses. Secondly, a finite element thermal analysis based on Ansys-Icepak is accomplished to validate the selected cooling system for the power converter. Thirdly, a co-simulation model is developed using Matlab-Simulink and LTspice® to evaluate the SiC power module impact on the performance of a multiphase drive system at different operating conditions. The results obtained show that the dynamic performance and efficiency of the power drive are significantly improved, which makes the proposed system an excellent candidate for future aircraft applications.

An Object-Oriented Modeling Approach to Virtual Prototyping of Marine Operation Systems Based on Functional Mock-Up Interface Co-Simulation

This paper presents an object-oriented modeling (OOM) approach to model development of marine operation systems, specifically the hydraulic systems of marine cranes. Benefited from the rapid development of computation technology, many modeling and simulation techniques and software tools have proved to be very useful during the product and system development process. However, due to the increasing complexity of the physical systems, many challenges still exist regarding model flexibility, model integration, simulation accuracy, stability, and efficiency. The goal of introducing OOM to complex dynamic systems is to provide flexible, effective, and efficient models for different simulation applications. Previous work presented a virtual prototyping (VP) framework based on the functional mock-up interface (FMI) standard. The advantage of using FMI co-simulation is that modeling and simulation of stiff and strongly coupled systems can be distributed. As a result, the modeling tradeoffs between simulation accuracy and efficiency can be evaluated. The essential features of OOM and its application within dynamic operation system domain are highlighted through a case study. These features include model causality, model encapsulation, and inheritance that facilitate the decomposition and coupling of complex system models for co-simulation. The simulation results based on the proposed VP framework showed speedups in the computation efficiency at the cost of moderate accuracy loss.

Acceleration of Simulated Fault Injection Using a Checkpoint Forwarding Technique

Simulated fault injection (SFI) is widely used to assess the effectiveness of fault tolerance mechanisms in safety-critical embedded systems (SCESs) because of its advantages such as controllability and observability. However, the long test time of SFI due to the large number of test cases and the complex simulation models of modern SCESs has been identified as a limiting factor. We present a method that can accelerate an SFI tool using a checkpoint forwarding (CF) technique. To evaluate the performance of CF-based SFI (CF-SFI), we have developed a CF mechanism using Verilog fault-injection tools and two systems under test (SUT): a single-core-based co-simulation model and a triple modular redundant co-simulation model. Both systems use the Verilog simulation model of the OpenRISC 1200 processor and can execute the embedded benchmarks from MiBench. We investigate the effectiveness of the CF mechanism and evaluate the two SUTs by measuring the test time as well as the failure rates. Compared to the SFI with no CF mechanism, the proposed CF-SFI approach reduces the test time of the two SUTs by 29%–45%.

Study of Dynamic Characteristics for Hydraulic System on 300MN Die-forging Press

The faults such as seal breakdown and pressure sensor damage occur in 300MN Die-forging press frequently. First, the fault phenomenon and harm of the hydraulic system was compiled statistics, the theoretical analysis of the hydraulic impact of hydraulic system are carried out based on the momentum theorem; Then, the co-simulation model of hydraulic system was established by AMESim and Simulink software and the correctness was verified. Finally, the dynamic characteristics of hydraulic system for the key working condition “forging stroke changing to mold collision” was analyzed, the influences rules of system parameters such as the leak gap of valve, diameter of water way pipeline, emulsion temperature and air contain act on hydraulic system are obtained. This conclusions have a theoretical guiding significance to the improvement and maintains of high pressure and large flow hydraulic system.

A Coupling Simulation and Modeling Method for High Temperature Superconducting Magnets

Under transient operating conditions, especially in the case of alternating current or pulse current, the high temperature superconducting (HTS) magnet will suffer ac losses leading to changes in the temperature and critical current distribution throughout the magnet. A magneto-thermal model is needed to simulate this process. In fact, the state change of the magnet will lead to a nonlinear performance of the HTS magnet in the power system. This paper introduces a coupling simulation and modeling method for the HTS magnet based on a cosimulation model built in MATLAB and COMSOL. The HTS magnet element is a customized module created via the self-code S-Function in MATLAB. A magneto-thermal finite element model based on the PDE and Heat Transfer modules of COMSOL is built into the S-Function. This model allows the state of the HTS magnet to be monitored during the operating process. A small-scale HTS magnet including three single pancake coils with a dc excitation system is illustrated to verify the nonlinear characteristic of the HTS magnet and the effectiveness of this coupling simulation and modeling method.

Detecting horizontal and vertical urban growth from medium resolution imagery and its relationships with major socioeconomic factors

ABSTRACTUrban growth consists of horizontal and vertical expansions. An integrative framework for estimating horizontal and vertical expansions of city urban areas using Landsat images was presented. It includes following steps: (1) a spectrum-based classifier (here Support Vector Machine) is first used to preclassify Landsat images; (2) the spectral similarity-enhanced Markov chain random field cosimulation model is then applied to postclassify the preclassified images and detect building shadows; and (3) a morphological operator based on spatial logic reasoning is used to estimate mid-rise or taller buildings (MTBs) from detected shadows. Both horizontal urban growth and vertical urban growth in the main city area of Guangzhou for the time period of 1993–2013 were detected. The accuracy of identified MTBs by shadows was validated to be 78.1% on average for 2013. The case study indicates that Guangzhou had undergone both horizontal and vertical urban growth from 1993 to 2013, and vertical urban growth followed horizontal urban growth successively. The relationships between the horizontal and vertical urban growth and three major socioeconomic factors during the studied period were analysed. Results indicate that both the total area of built-up areas and the total area of detected MTBs are significantly correlated with population density, real gross domestic product, and fixed investment (i.e. investment in fixed assets such as land, buildings), respectively. While population density is the major driving force of horizontal urban expansion, fixed investment is the major driving force of vertical urban expansion for the city as a whole. Although the method is not perfect currently in detecting MTBs in various situations and the case study is mainly exploratory, the proposed framework and the case study can be helpful in quantitatively exploring the horizontal urban growth and vertical urban growth of a city and their causes.

The Coordinated Control of Wheeled Mobile Robot on Loose Soil

Generating the coordinated tractive force of each wheel for the robot is an important control objective in order to ensure the wheels to be the driven wheel but not the towed wheel. The tractive force is different between the front wheel and the following rear wheel because of the wheel’s unequal sinkage caused by the compaction of loose soil. In this study, the mathematical model of sinkage is established to investigate the influence of repetitive passing on wheel sinkage, and the wheels’ tractive performance is deduced on basis of the terramechanics. The equal drawbar pull generated by all the wheels under the optimal efficiency analysis is defined as the index to evaluate the wheel’s motion consistency, as well as the coordinated control objective of wheeled mobile robot on loose soil. Furthermore, dynamic model of a six-wheel mobile robot is established and the fuzzy sliding mode controller is designed. Meanwhile, the validity of the proposed modeling and control method is demonstrated through the ADAMS co-simulation model. The result shows that control system has good performance in simulation.