Sharif Digital Repository

This paper presents an active suspension system for passenger cars, using adaptive critic-based neurofuzzy controller. The model is described by a system with seven degrees of freedom. The car is subjected to excitation from a rode surface and wheel unbalance. The main superiority of the proposed controller over previous analogous fuzzy logic controller designed approaches, e.g., genetic fuzzy logic controller, is its online tuning characteristic and remarkable reduced amount of computations used for parameter adaptation, which makes it desirable for real time applications. Considering the simplicity of this controller and its independence from the system model, this control method has the... 

This paper first will describe @Home Mobile Robot and DC motors. In continuous, is designed a Direct current (DC) motor for special task due to specific speed diagram for considered robot. This robot wants to work in intermittent operation condition. Finally is done a speed control on a selected permanent magnet brushed DC motor using of Linear-Quadratic-Regulator (LQR), Linear-Quadratic-Gaussian (LQG) and Fuzzy logic controllers  

This paper focuses on the biomechanical aspects of human load carrying in order to provide a physiological framework for designing the more anthropometric assistive systems. An 8degrees-of-freedom musculoskeletal model with twenty functional muscle groups in the lower extremity was developed to simulate the movement in sagittal plane. Inverse dynamics based optimization approach was employed to estimate the excitation level of the muscles. Activation patterns of the muscles illustrate the importance role of the soleus in supporting of the body during load carrying. Also power distribution analysis of the muscles reveals that the plantar flexors of the ankle, extensors of the knee and hip... 

This paper will first describe the Linear-Quadratic-Gaussian (LQG) and Lead-Compensator when the Proportional-Integral-Derivative (PID) controllers are inactive for procedures that have large delay time (LDT) in transfer stage. Therefore in those states, LQG and Lead Compensator perform better than the PID controllers. The constrained LQG is optimal and stabilizing. The solution algorithm is guaranteed to terminate in finite time with a computational cost that has a reasonable upper bound compared to the minimal cost for computing the optimal solution. In this work all actual working area condition for instance noises and disturbances are considered. Eventually, LQG and Lead Compensator have... 

In this paper, we consider a control strategy of multi-robot systems, or simply, swarms, based on emotional control technique. First, we briefly discuss a "kinematic" swarm model in n-dimensional space introduced in an earlier paper. In that model, motion of every swarm member is governed by predefined inter-individual interactions. Limitations of every member's field of view are also considered in that model. After that, we consider a general model for vehicle dynamics of each swarm member, and use emotional control theory to force their motion to obey the dynamics of the kinematic model. Based on the kinematic model, stability (cohesion) analysis is performed and coordination controller.is... 

In this paper, we consider a control strategy of multi-robot systems, or simply, swarms, based on emotional control technique. First, we briefly discuss a "kinematic" swarm model in n-dimensional space introduced in an earlier paper. In that model, motion of every swarm member is governed by predefined inter-individual interactions. Limitations of every member's field of view are also considered in that model. After that, we consider a general model for vehicle dynamics of each swarm member, and use emotional control theory to force their motion to obey the dynamics of the kinematic model. Based on the kinematic model, stability (cohesion) analysis is performed and coordination controller is... 

Buried pipe lines are an efficient way of transporting of water, sewage, oil, and gas resources in all over the world. Since the buried pipe lines are exposed to many unexpected conditions, such as landslides, corrosion, fatigue, earthquakes, material flaws or even intentional damaging, so the inspection requirements lead to adoption of new method of maintenance, protection and conserving. This report aims to improve the trustworthiness, reliability, yet economical technologies for monitoring of behavior and manner of buried pipe lines during operation and assessing the risk of pipe lines failure. Distributed sensors (piezoelectric) are surface designed and embedded to investigate the... 

This paper presents an attempt to control the chaotic behavior of Rayleigh-Bénard convection system in weakly elastic fluids. In this article, a nonlinear model is presented which fundamentally refers to a model introduced by Khayat. The nonlinear model has chaotic behavior which is controlled by using sliding mode method. In the presence of uncertainty for some parameters of the model, a controller is designed to stabilize the dynamic of the system on the desired trajectory. Different simulation results are presented to demonstrate the effectiveness of the designed controller in tracking different desired trajectories. ©2009 IEEE  

Due to the nonlinear dynamics of hydraulic systems, applying high performance closed-loop controllers is complicated. In this paper, a single-rod hydraulic actuator is considered in which load displacement (for positioning purposes) is controlled via manipulation of the input voltage to the servo-valve. Dynamics of the servo-valve is described by first and second order transfer functions (named as Models 1 and 2). Through linearization of the system around its operating points, dynamics of the hydraulic actuator is represented in the state space. A full-order observer is designed for on-line states estimation. Then, feedback control system is designed for both regulation and tracking... 

Naturalness in Text-to-Speech (TTS) systems is very important in achieving high quality waveform. The naturalness of the waveform is highly correlated to phonetic coverage and prosodic features such as loudness, duration and pitch. This paper addresses the implementation of a prosodic TTS for Azeri. The TTS system to which the prosodic information is added, is a concatenative synthesizer based on diphones. For adding prosody and increasing naturalness, we have obtained a primary pitch curve for each word, based on the location of the stressed syllable. Also using sentence type effects, the final pitch contour has been modified. As far as we know, the output speech that is produced with this... 

The vibration suppression of semi-actively controlled jacket-type offshore platforms using Magnetorheological (MR) dampers is studied. The main goal of using MR damper system is to reduce vibration caused by wave hydrodynamic forces. A fixed jacket-type offshore platform affected by wave-induced hydrodynamic forces and controlled by MR dampers is modelled as a semi-active controlled system with 30 DOFs. In comparison with earlier studies, an improvement in problem modelling is made. Based on the wave theory and Morison equation, an exosystem is designed to simulate regular wave forces. The necessary input voltage to MR dampers to generate desired damping force is derived by clipped optimal... 

In this paper, a novel design approach for determination of the optimal Fractional Order PID (FOPID) controllers, using the Particle Swarm Optimization (PSO) method is presented. Fractional calculus can provides good performance and robustness for FOPID controllers in comparison with the conventional PID and even other types of classical controllers, because of the arbitrary order of fractional calculus presented in this scheme. This paper demonstrates in details how to employ the PSO method to search efficiently for the optimal FOPID controller parameters in SISO and MIMO systems. The proposed approach is applied to an electromagnetic suspension system as an example to illustrate the design... 

The Dual-Arm Cam-Lock robot is a reconfigurable manipulator formed by two parallel cooperative arms. Based on the application, these arms may loose some degrees of freedom by locking into each other. However, they are considered as redundant arms when operating without any locked joints/links. In this paper, a method is introduced to find the optimal configuration of this manipulator. The objective is to find the configuration in which maximum cooperative force is exerted to an object in a specific direction. The dynamics of the robot is parametrically formulated for different configurations, and by considering the geometrical constraints optimization is performed using fine-mesh and genetic... 

The dynamics of the flexible robot arm subjected to tip mass during an actual deployment is studied. The Euler-Bernoulli beam theory and the real deployment are considered in the simulation. A new real axial velocity profile is developed. This new suggested profile simulates the actual deployment such that the arm movement starts from immovability and after attaining the final required length comes back again to the static state. Using Lagrange's equation, the equations of motion of the system are derived to study the system dynamics in this suggested deployment profile. A series approximation is used to represent the lateral elastic displacements. Using variables separation and also some... 

In this paper, the agent velocity in robotic swarm was determined by using particle swarm optimization (PSO) to maximize the robotic swarm coordination velocity. A swarm as supposed here is homogenous and includes at least two members. Motion and behavior of swarm members are mostly result of two different phenomena: interactive mutual forces and influence of the agent. Interactive mutual forces comprise both attraction and repulsion. To be more realistic the field of the swarm members' view is not infinity. So influence of the coordinator agent on the robotic swarm would be local. The objective here is to guide the robotic swarm with maximum possible velocity. According to equation motion... 

In this paper, the agent velocity in robotic swarm was determined by using particle swarm optimization (PSO) to maximize the robotic swarm coordination velocity. A swarm as supposed here is homogenous and includes at least two members. Motion and behavior of swarm members are mostly result of two different phenomena: interactive mutual forces and influence of the agent. Interactive mutual forces comprise both attraction and repulsion. To be more realistic the field of the swarm members' view is not infinity. So influence of the coordinator agent on the robotic swarm would be local. The objective here is to guide the robotic swarm with maximum possible velocity. According to equation motion... 

In this paper, nonlinear vibration of a micro cantilever exposed to a constant velocity flow is studied. In order to obtain vibration frequency and time response of the micro beam the variational iteration method is used as a novel tool for solving nonlinear differential equations. Results of the analytical solution are compared with those obtained by Runge-Kutta method which shows very good agreement between them. Results confirm that frequency of vibration depends on the flow velocity. Also, the high sensitivity of the vibration frequency to the flow velocity means that it can be an effective indicator of velocity  

An integrated procedure for mathematical modeling and power control balance for a SPA (Split Parallel Architecture) hydraulic hybrid vehicle is presented in this paper. Dynamic mathematical model of the powertrain is constructed firstly, which includes five modules: diesel engine, traction motor, starter, loading pump and accumulator. Based on the mathematic model of control modes a stability analysis is done. For some control modes a Sliding Mode Control is designed, which uses full-states closed-loop feedback. The paper finally illustrates and discusses the results of simulation. The results show that the performance and stability of control modes are proper and a power control strategy... 

Dynamic behavior of a electrostatically actuated MEMS resonator is investigated. A double clamped micro-beam under distributed DC and AC actuation is used. Corresponding single degree of freedom model is derived using Galerkin's decomposition method. Homotopy Perturbation Method (HPM) is implemented in order to derive analytical expression for frequency response of the micro-resonator. Comparison of the obtained results with the numerical simulations confirms that HPM agrees very well with numerical simulations for a wide range of parameters. Obtained analytical solution can be used for design and optimization of MEMS resonators