dynamic modeling

Piezoelectric dispensers are widely applicable devices across many industries. However, their electromechanical structure often poses complexity in dynamic modeling. The interplay of many components especially compliant mechanisms and piezoelectric actuators makes modeling of the system challenging. In this study, the components of the system have been modeled individually and coupled together to predict the system behavior. For analyzing the bridge-type compliant mechanism, an appropriate method is proposed to model the structure with limited states. The mentioned method can predict the component behavior without sacrificing the precision which makes it ideal for coupling with other components' dynamics. Additionally, a non-linear modeling approach is introduced to capture the piezoelectric non-linear hysteresis behavior. Finally, by coupling the whole system dynamic, a comprehensive model is reached. The model developed for the compliant mechanism is individually validated by FEM software and experiments to prove the accuracy. The hysteresis nonlinear model is also identified and validated with the experiments with R squared exceeding 0.98. The entire coupled dynamics of the electromechanical system are identified and tested across several input frequencies. R-squared values exceed 0.95 for all input frequencies, affirming the accuracy of the dynamic model. Overall, the developed model is functional in the design and optimization of piezoelectric dispensers, as well as in automatic control system designs.

Despite the extensive progress in the field of biomechanics of human gait, a suitable gait model with the ability to simulate the control system of the human brain has not yet been presented, especially in 3D mode. The importance of the issue increases when the simulation of human walking is one of the main requirements of designers of biomechanical equipment such as artificial organs, wearable robots and humanoid robots. Regarding the constraints and complexities of previous studies, in this research, a forward dynamic 3D model of gait based on sliding mode controller (SMC) is presented, which simulates the walking behavior of healthy individual on the ground in different movement phases. One of the strengths of this research is the comprehensive and analytical review of 3D rotation consequences of the joints coordinate systems, which is done with 11 DOF inverse dynamic model. Based on the obtained results, the SMC controller is well able to produce stable 3D human gait. Also, in 3D gait analysis, the Cardan rotation sequence is not suitable and YXZ order should be used. This outcome is a very useful result for 3D motion generation for human like walking pattern. The results of this study can be used in the design of humanoid robots, active and passive prostheses. Also, the presented model can simulate the walking of an amputee with a prosthesis and the role of the controller in the path, which is very important and beneficial in terms of rehabilitation.

This research aims to model the nonlinear dynamics of the space propulsion system equipped with an electro-pump. For modeling, this system includes the combustion chamber, fuel and oxidizer tanks, and the corresponding pressurization system. A set of governing equations has been modeled in the Simulink of MATLAB software. The results of the modeling including changes in the angular velocity versus the time, changes in combustion chamber pressure versus the time, and changes in the mass flow rate of the fuel and oxidizer to the combustion chamber versus the time, are presented. In the end, the obtained results are compared with the results of the available engine and in addition to validating the results, it is possible to confirm and validate the performance of the electro-pump in a liquid fuel engine. The results showed that the angular velocity rate, the average acceleration rate of the combustion chamber, the average flow rate of the oxidizer to the combustion chamber and the average flow rate of the fuel to the combustion chamber obtained from the simulation and the available reference have a maximum error of 20%. The amount of difference in the conceptual design stage is free of problems. In addition, the trend of the graphs is similar.

The use of a systematic view has increased to deal with social and environmental problems in recent years. Recently, various models have been developed to address urban water issues. Most of them are focused on runoff and storm water management and few have addressed the problems of the Drinking water system. However, the lack of an effective model that supports complex and multi-objective urban water system in terms of management and decision-making is felt. This article focuses on the importance of a sustainable approach to the conventional approach in urban water management and the need to change attitudes due to the current state of water resources. In this paper a novel system dynamics model has been developed, taking into account the technical, economic, social, environmental and government subsystems that simulate and predict the results of urban water management measures. The results of the implementation of the proposed model on the city of Isfahan showed that the model has a high precision in simulating system condition. The model error rate in simulation of different parameters is less than 5%. Therefore, the model can be used as a tool for analyzing different management strategies before implementing and spending time and cost to assist decision makers.

Pneumatic Soft bending actuators as safe and highly adaptable robots are being considered by researchers, such that they become an ideal choice for making devices that interact more with humans. These advantages come along with several disadvantages. Their great adaptability is provided by their high degrees of freedom, and consequently, it makes the modeling a significant challenge for researchers. In this paper, the modeling of a soft fiber-reinforced bending actuator that is in contact with the environment has been conducted by utilizing the finite rigid element method. This method provides a context within which the modeling theories of traditional rigid robots, such as the Denavit-Hartenberg method, become usable for a soft continuum actuator. Therefore, in the following, resorting to this theory, the static and dynamic behavior of a soft actuator under the effect of the external load has been investigated and compared with the empirical results derived from a fabricated actuator. The results show a minimum accuracy of 9 percent, although being as simple as can be used for other purposes like implementing control systems based on that.

As a subset of mobile robots, the tractor-trailer mobile robot has been widely used in various applications in the past decades, including military and civilian missions, due to its advantages, such as a more expansive working space, high maneuverability, and load-carrying capacity has been used. One of the main challenges in controlling the tractor-trailer robot's speed is the tractor drives' dynamics. In this article, to complete the modeling after investigating the kinematic and dynamic equations governing the tractor-trailer robot, coupled dynamics have been presented by considering the dynamics of the tractor wheels. In the following, using the coupled dynamics, a suitable controller has been designed to control the robot's speed to achieve the desired value and the position point by point. Various simulations are presented to demonstrate the dynamic performance and the proposed controller. According to the simulation results, the presented theory improves the performance of the designed control system.

In this paper, the effect high penetration of renewable energy resources on the transmission network stability is investigated. By increasing the number of inverter-based resources, the overall inertia of the network decreases and the stability of the network is affected. In order to analyze the behavior of low-inertia grids, initially according to the type of traditional power plants and wind turbines, appropriate dynamic modeling has been done. Then, by creating a short circuit, the effect of increasing the penetration of wind turbines on the voltage and frequency stability is evaluated. The effect of duration and location of the fault on network stability has also been investigated. The study network is a modified Kundur’s four-machine system modeled in PowerFactory.

Machines with permanent magnet excitation have higher efficiency and more reliability than machines with electric excitation. Among the permanent magnet machines, the crossover machines have a higher ratio of power to volume and electric torque to volume, so that at the same power, their size is smaller than the usual permanent magnet machines. And this is the reason why researchers have paid attention to crossover machines in recent years. Cross-phase generators can be made with a smaller pole pitch than other machines. These features make these machines have a higher power density than other permanent magnet machines. The copper winding of the crossover generators is simple, and their passive copper winding is considerably less than other machines, so the mass of active materials required to produce power and electric torque can be less than other machines. In other words, a smaller volume of active materials per unit of electric torque can be obtained by these machines. Therefore, this generator creates high power and torque by creating a large number of poles and a small pole pitch, and it can be a suitable option for use in the production of electrical energy from wind power, especially at low wind speeds.  The lack of a suitable dynamic model and the application of this generator, dynamic modeling and simulation, are necessary to analyze its performance under different conditions. Therefore, this article presents a dynamic model for this generator to be connected to the wind turbine, and then simulates the wind turbine based on this generator by simulating the turbine-generator system.

The design of a controller for a thrust vector control system of UAV has been studied through the robust  H∞ control method. In the first, the governing space-state equations of the system have been derived using the bond graph approach. Then, the critical performance parameters of the system were evaluated and identified according to the operational feasibility and the range of successful performance of the system. Next, the weight functions of the robust H∞,including the indeterminate weight function under the influence of specified uncertainties, were determined. Finally, the consistency of robust control in the presence of uncertainties was evaluated and the results of deflection of thrust vectoring nozzle were compared with the performance results of an optimized PID controller. The simulation results are determined using the MATLAB environment. The results of this study showed that the bond-graph method has good validity for modeling of this system and the designed robust controller can also meet its mission requirements

Due to the limited resources of fossil fuels and the pollution caused by them, the use of clean fuels seems necessary. In this regard, the development of electric or hybrid vehicles has great importance. In recent years, research areas related to autonomous electric vehicles have attracted the attention of automotive researchers and industrialists. These cars have different categories in terms of capabilities, including intelligent vehicle speed control. In this paper, dynamic modeling and longitudinal speed control of a level-one autonomous electric vehicle using GT-SUITE and MATLAB are investigated. Also, the model created in GT-SUITE software is validated with the help of data obtained from open-loop experimental tests. Then, after connecting the two software, the proportional-integral controller is designed to control the longitudinal speed of the vehicle and its parameters are adjusted.  Finally, the performance of the designed controller in controlling the vehicle speed in the presence of various conditions (road slope, wind blowing, and different velocity reference inputs) is evaluated.

This paper focuses on 3-D dynamic modeling of a transport quadrotor with cable in the presence of load generating stochastic forces. In many practical cases, we are dealing with payloads that generate oscillating forces with random amplitude and frequency by their inherent dynamics or interacting with the environment. These forces can greatly affect the dynamics of the transport system. The innovation of the present study is to consider these forces and show their impact on quadrotor’s dynamics. Furthermore, in order to make the model more compatible with the real system, it is assumed that the connection point of cable and quadrotor is not located on the center of gravity of flying vehicle and the cable's inertia is considered in the modeling process. To this end, the systems’ equations of motion are derived based on both Euler-Lagrange and Newton-Euler methods. After obtaining equations of motion, the verification of the model is investigated in three steps. In the first step, by performing simulation, the validity of the nonlinear model is investigated and dynamical analysis is expressed. In the next step, by evaluating the structure of the model, it is shown that the equations of motion satisfy some structural features of a desirable dynamic model. Then, by setting some parameters and variables to zero, it is shown that simpler models provided in some references can be achieved from this comprehensive model. At the end, the conclusion of this work is presented.

The fuel cell, as an efficient and environmentally friendly energy source, has received much attention in recent years. In this paper, a comprehensive model of the 6-kW proton exchange membrane (PEM) fuel cell, including dynamic model along with the electrical model, is presented. The mass balance and thermodynamic energy balance, temperature dynamics, open-circuit output voltage, voltage losses, and the formation of charge double layer in the PEM fuel cell are modeled. The connection of fuel cells to the microgrids in applications such as distributed power generation, power systems of naval defense systems, and military ships requires DC-DC power converters with high voltage gain, high capability of power processing, and high levels of current absorbed from the dc source. In this context, this paper proposes the use of an interleaved boost DC-DC converter and an interleaved boost with voltage multiplier converter (IBVM) to connect the fuel cell to the microgrids. Then a model predictive control algorithm is proposed for the two proposed converter as a current-mode controller to control the injected current by fuel cell as well as to smooth output fluctuations of the fuel cell. Compared with traditional cascade linear control, the proposed scheme avoids PID parameters tuning, PWM modulation, and coordinate transformation. The simulation results are given to confirm the effectiveness of the proposed control method, the chosen converters, and the obtained model of PEM fuel cell.

The effect of climatic and climatic changes in different geographical areas on the types of plants, animals and objects and the importance of protecting the items has led to the study of ideas related to control of air variables in desired conditions. All of the ideas studied in this field lead to the separation of under the control area in order to reduce the effect of the environment on the control variables. This area is then modeled as a system with a defined energy and mass exchange with the environment. In the present study, thermal modeling, dynamic modeling, and control of the variables of a museum which is considered an enclosed area have been investigated. For dynamic modeling, the one-dimensional heat transfer method is used for area elements (DETECt 2.3.1 method). After dynamic modeling, temperature and humidity control have been done using model-reference and modified adaptive methods. Numerical simulation results include the behavior of the system with and without using the controller, the variation of the dynamic variables, and changes in the control signal and the adaptive gains. The results show the success of control methods in the control of temperature and humidity of the studied area.

In this paper, the influence of the rotor circuit on the characteristics of the brushless doubly-fed induction machine (BDFIM) is investigated. For this purpose, a dynamic model is provided for the nested-loop BDFIM. The model is based on the coupled circuits of the stator windings and the rotor loops. By using the winding function method, the self- and mutual-inductances of the coupled circuits are obtained as functions of the rotor position and design parameters. This model is used as a fast tool to predict the dynamic performance of the BDFIM and is verified by means of time-stepping Finite Element Analysis (FEA). Using the provided dynamic model, some characteristics of the BDFIM such as the Joule loss and the magnetic coupling between the power and control windings at no-load conditions are studied. Using the developed model, the effect of the number and the arc span of the rotor loops on the no-load characteristic of the BDFIMs is studied.