Sharif Digital Repository

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... 

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  

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 mechatronic design of a novel mechanism for ball and plate system is discussed. A webcam provides the system with feedback of the ball's position. A heuristic technique for image processing is introduced. The kinematics and dynamics of the system are also described. Supervisory fuzzy control and sliding control techniques are proposed to perform position control for the system. Experimental results corroborate the validity of the controllers. © 2008 IEEE  

In this paper, important issues that could come up in practice of Active Disturbance Rejection Control (ADRC) due to a common assumption and some inevitable practical restrictions are investigated. The main idea behind ADRC is modeling effects of both internal uncertainties and external disturbances as an extra state called the total disturbance which is timely estimated. In the majority of recent works, it is assumed that time derivative of total disturbance is bounded. First we prove that, beside the system characteristics, the validity of this assumption strongly depends on the tuning parameters, even in the case of simple classes of linear second order systems. Thus, one should be... 

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... 

Effects of fringing electrostatic fields on the behavior of a double clamped initially curved microbeam are investigated. Galerkin's decomposition method is applied on the governing Euler-Bernoulli equation with distributed electrostatic force to obtain the lumped-parameter model of the system. The resulting single degree of freedom model is obtained with the Palmer's formula as a model for the fringing field effects. To derive an applied form of the fringing field effect in lumped model, we have used Genetic Algorithms as an optimization method. Then using the lumped model, we have investigated the system nonlinear dynamics. Comparison of the obtained bifurcation diagrams with 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  

The canonical problems in control of the biped robots arise from underactuation, impulsive nature of the impact with the environment and existence of the many degrees of freedom in their mechanism. Since biped walkers have fewer actuators than degrees of freedom, they are underactuated mechanical systems. In this paper according to the humans and animals locomotion algorithms, the stability of an underactuated biped walker with point feet is done by Central Pattern Generator (CPG) and feedback networks. For tuning the parameters of the CPG network, the control problem is defined as an optimization problem. This optimization problem is solved by using of Genetic algorithm. Also a new feedback... 

Micro/Nano mechatronic systems might be defined as systems that include nano- or micro-scale components. These components can be sensors, actuators, and/or physical structures. Furthermore, the high-precision control laws for such small scales are important to ensure stability, accuracy, and precision in these systems. In this writing, four categories of such small-scale systems are considered by providing multifarious novel or key examples from the literature: control engineering and modeling, design and fabrication, measurement engineering, and sensor/actuator development. The applications discussed in the examples vary from nano-positioners, crucial in systems such as atomic force... 

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... 

The proposed current harmonic model for high-power synchronous machines is dependent on the inductances of quadrature and direct axes. Variation of these parameters, as a consequence of modification in operating point, aging and temperature rise, in-progress pulse patterns, are no longer optimal solutions for minimization of harmonic losses. On the other hand, offline calculation of optimal pulse patterns for slight changes in these parameters, and storing them in read-only memories to serve as look-up tables, give rise to immoderate computational burden and unmanageable look-up tables. Notwithstanding performing online identification process and offline calculation of optimal pulse... 

In this paper a linear delayed feedback control is proposed and experimentally applied to eliminate chaos in a nonlinear electrical circuit which is known as Sprott circuit. The chaotic behavior of the system is suppressed by stabilizing one of its first order Unstable Periodic Orbits (UPOs) by a controller designed based on so-called Pyragas method. The effectiveness of this method, firstly, is numerically investigated by stabilizing the unstable first order periodic orbit and then verified experimentally by a laboratory setup. ©2007 IEEE  

Cooperative systems have been extensively investigated in literature. Herein the criteria and implementation for finding the optimal configuration of the Dual-Arm Cam-Lock (DACL) robot manipulators at a specific point with the objective to optimize the applicable task-space force in a desired direction are addressed. The DACL robot manipulators are reconfigurable arms formed by two parallel cooperative manipulators. Some of their joints may lock into each other. Therefore, the arms normally operate redundantly. However, when higher structural stiffness is needed these two arms can lock into each other in specific joints and loose some degrees of freedom. The dynamics of the DACL robot is... 

In this paper, a novel thermal microactuator is designed which is capable of producing bi-directional lateral and rotational output and one of its applications as a two DOF micromanipulator is shown. Also, by carefully choosing the doping level, temperature distribution is determined by considering the dependency of silicon's resistivity and conductivity to temperature. Using variable separation method an equation in terms of elliptic integrals is reached and after imposing boundary conditions the exact temperature distribution is obtained numerically. Currents at each branch is updated due to the last temperature distribution and this process is repeated several times until the final... 

In this paper, a novel microfabrication process of a six DOF thermal compliant nanopositioner is presented. The microfabrication process was based on bulk micromachining process. By using this process some important operational restrictions which are usually created by surface micromachining were removed. Moreover, this novel process does not need SOI wafers and needs only ordinary wafers. Therefore, it makes microfabrication process cheaper than surface micromachining processes where SOI wafer should be used. This method is completely appropriate for microactuators which have 120 degree misalignment. Finally, a primary test by using interferometer method was used to test connection of... 

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  

This paper presents an offline path planning method in 3D space for a surveillance aerial vehicle. In this method, the aerial vehicle is supposed to visit particular points on the path, and the collision between the vehicle and the fixed obstacles in the environment must be avoided. In order to accomplish the mission, first, the path is generated using B-splines. Then, the feasibility of tracking the designed path for the vehicle is considered by analyzing the vehicle's dynamic constraints, such as limitations on deflections of control surfaces. The analysis is supported by a simulation. Potential extension of the proposed analysis to multiple aerial vehicles has been also discussed at the... 

Aerial tail-sitters have drawn many attentions in recent years. The main challenge of employing these vehicles is to ensure safe and efficient takeoff and landing. The aim of the current study is to develop a gradient-base optimization algorithm for a jet aerial tail-sitter in order to obtain minimum time trajectories in transition flight phases. The vehicle is supposed to utilize thrust vectoring system instead of conventional control surfaces that will pose minimal drawbacks in terms of low speed efficiency and complexity. The time-optimal trajectories are computed using the nonlinear dynamic equations of motion of the vehicle in order to make sure that the vehicle can follow the optimum...