Sharif Digital Repository

This study deals with a generalised version of lead/lag compensators known as fractional-order lead/lag compensators. Exact and simple formulas are found for designing this introduced type of fractional-order compensators in order to provide the required magnitude and phase at a given frequency. Also, the region in the phase-magnitude plane, which is accessible by these compensators, is analytically found. Moreover, numerical examples and experimental results are presented to show the applicability of the achievements of this study in control system design  

Unmanned helicopters have gained great importance during recent years due to their special abilities such as hover flight, vertical take-off and landing, maneuverability and superior agility. The advances in electronic devices technologies lead to more powerful and lighter processors to be used in avionic systems which have attracted more attention to these UAVs. The first steps of utilizing an unmanned helicopter are dynamic modeling, control system design and performing model-in-the-loop (MIL) and hardware-in-the-loop (HIL) tests which are presented in this paper. In this research, MIL and HIL tests of an unmanned helicopter are done using novel Linux-based flight control system built on... 

Unmanned helicopters have gained great importance during recent years due to their special abilities such as hover flight, vertical take-off and landing, maneuverability and superior agility. The advances in electronic devices technologies lead to more powerful and lighter processors to be used in avionic systems which have attracted more attention to these UAVs. The first steps of utilizing an unmanned helicopter are dynamic modeling, control system design and performing model-in-the-loop (MIL) and hardware-in-the-loop (HIL) tests which are presented in this paper. In this research, MIL and HIL tests of an unmanned helicopter are done using novel Linux-based flight control system built on... 

Unmanned helicopters have gained great importance during recent years due to their special abilities such as hover flight, vertical take-off and landing, maneuverability and superior agility. The advances in electronic devices technologies lead to more powerful and lighter processors to be used in avionic systems which have attracted more attention to these UAVs. The first steps of utilizing an unmanned helicopter are dynamic modeling, control system design and performing model-in-the-loop (MIL) and hardware-in-the-loop (HIL) tests which are presented in this paper. In this research, MIL and HIL tests of an unmanned helicopter are done using novel Linux-based flight control system built on... 

As the first review in this field, this paper presents an in-depth mathematical view of Intelligent Flight Control Systems (IFCSs), particularly those based on artificial neural networks. The rapid evolution of IFCSs in the last two decades in both the methodological and technical aspects necessitates a comprehensive view of them to better demonstrate the current stage and the crucial remaining steps towards developing a truly intelligent flight management unit. To this end, in this paper, we will provide a detailed mathematical view of Neural Network (NN)-based flight control systems and the challenging problems that still remain. The paper will cover both the model-based and model-free... 

A new method of integrated guidance and control for homing missiles with actuator fault against manoeuvring targets is proposed. Model of the integrated guidance and control system in the pitch plane with actuator fault and some uncertainty is developed. A control law using combination of adaptive backstepping and sliding mode approaches is designed to achieve interception in the presence of bounded uncertainties and actuator fault. Simulation results show that new approach has better performance than adaptive backstepping and has good performance in the presence of actuator fault  

Purpose - The purpose of this paper is to develop a novel solution for the predicted error and introduces a systematic method to develop optimal and explicit guidance strategies for different missions. Design/methodology/approach - The predicted error is derived from its basic definition through analytic]al dynamics. The relations are developed for two classes of systems. First, for systems in which the acceleration commands are truncated at a specified time. Second, for systems in which the corrective maneuvers are cut off at a specified time. The predicted error differential equation is obtained in a way that allows for derivation of several optimal and explicit guidance schemes. Findings... 

The loads induced on the spacecraft orbiting the Earth by the deploying elastic arm are investigated. The coupled equations of motion of the arm with the vehicle orbital mechanics are used to describe the 3D dynamic behavior of the flexible-appendage and the related disturbing loads induced on the spacecraft. To this end, an equivalent dynamical system is derived for the arm by applying an attached Non-Newtonian Reference Frame which is subjected to the orbital motion and geocentric pointing maneuver of the spacecraft. With the help of the Assumed Modes Method, the behavior of the arm attached to the spacecraft in Keplerian orbits is studied. The results show that deploying the arm in some... 

Due to their agile manoeuvrability and simplicity of construction, quadrotor are employed in a variety of applications. Most of their expenses are due to complex control systems, since, to reduce these expenses, low cost control methods which are based on linear models should be used to achieve an autonomous flight. First, the process of accurate dynamic modeling of a sample quad rotor which is simulated by MATLAB SIMULINK is presented. Then, a frequency sweep input stimulates the virtual model in order to identify a linear model based on frequency response analysis. Consequently, the desired linear model is obtained in both hover and yaw mode of motion. However, pitch and roll mode were too... 

In this paper, we propose a leader following control for autonomous air robots. The separated design strategy with kinematic acceleration commands is used. The location of the robot with respect to the leader is specified by a range and two angles. We obtain the kinematic model of the system represented by the state-space equations. The controller is designed based on the sliding mode control which asymptotically stabilizes the tracking errors in presence of uncertainties and disturbances. In order to implement the leader following controller in the air robots, a control system is introduced which converts the acceleration commands to the actuator commands. Simulations are provided to show... 

A practical procedure is developed for the design of passive control systems using viscous fluid dampers for nonlinear structures. The design methodology takes advantage of the modification of the damping, strength, and stiffness properties of the structure to achieve the desired relative displacement and absolute acceleration response. For this purpose, a study of poles in the complex plane is used to determine the required changes in the dynamic properties of nonlinear structures. Furthermore, a relatively simple relation between the ductility demands of highly damped single- and multiple-degree-of-freedom (SDF and MDF respectively) systems is established to reduce the computational burden... 

The governing differential equation of motion for an undamped thin rectangular plate with a number of bonded piezoelectric patches on its surface and arbitrary boundary conditions is derived using Hamilton's principle. A moving mass traveling on an arbitrary trajectory acts as an external excitation for the system. The effect of the moving mass inertia is considered using all the out-of-plane translational acceleration components. The method of eigenfunction expansion is used to transform the equation of motion into a number of coupled ordinary differential equations. A classical closed-loop optimal control algorithm is employed to suppress the dynamic response of the system, determining the... 

ABSTARCT: A practical procedure is developed for the design of passive control systems using viscous fluid dampers for nonlinear structures. The design methodology takes advantage of the modification of the damping, strength, and stiffness properties of the structure to achieve the desired relative displacement and absolute acceleration response. For this purpose, a study of poles in the complex plane is used to determine the required changes in the dynamic properties of nonlinear structures. Furthermore, a relatively simple relation between the ductility demands of highly damped single- and multiple-degree-of-freedom (SDF and MDF respectively) systems is established to reduce the... 

In the field of mobile robotics, legged locomotion plays an essential role in transporting robots over various terrain types. A significant portion of research on legged robots has been focused on one-legged robots. In contrast with different types of locomotion of multi-legged robots, one-legged robots have only one type of motion, called hopping. Hopping motion, as a type of hybrid behavior, is generally comprised of flight and stance phases. Dynamic stabilizing of hopping motion provides a challenging control problem because of its nonlinear and hybrid behavior. The majority of one-legged hopping robots investigated so far are only capable of hopping with one side of their leg. In this... 

The governing differential equation of motion for an undamped thin rectangular plate with a number of bonded piezoelectric patches on its surface, and arbitrary boundary conditions are derived using Hamilton's principle. A moving mass traveling on an arbitrary trajectory acts as an external excitation for the system. The effect of moving mass inertia is considered using all the out-of-plane translational acceleration components. The method of eigenfunction expansion is used to decouple the equation of motion into a number of coupled ordinary differential equations. A classical closed loop optimal control algorithm is employed to suppress the dynamic response of the system by determining the... 

In this paper, a new reinforcement learning approach is proposed which is based on a powerful concept named Active Learning Method (ALM) in modeling. ALM expresses any multi-input-single-output system as a fuzzy combination of some single-input-singleoutput systems. The proposed method is an actor-critic system similar to Generalized Approximate Reasoning based Intelligent Control (GARIC) structure to adapt the ALM by delayed reinforcement signals. Our system uses Temporal Difference (TD) learning to model the behavior of useful actions of a control system. The goodness of an action is modeled on Reward-Penalty-Plane. IDS planes will be updated according to this plane. It is shown that the... 

The complexity associated with musculoskeletal modeling, simulation, and neural control of the human spine is a challenging problem in the field of biomechanics. This paper presents a novel method for simulation of a 3D trunk model under control of 48 muscle actuators. Central pattern generators (CPG) and artificial neural network (ANN) are used simultaneously to generate muscles activation patterns. The parameters of the ANN are updated based on a novel learning method used to address the kinetic redundancy due to presence of 48 muscles driving the trunk. We demonstrated the feasibility of the proposed method with numerical simulation of experiments involving rhythmic motion between upright... 

In this paper, the design of a formation flight controller is investigated. Each vehicle in the formation is controlled by designing two separate control loops. The formation flight controller placed in the outer loop employs behavior-based control as a distributed control strategy to steer the vehicle by producing acceleration commands and the control system placed in the inner loop is to convert these commands to the actuator commands. Leader following architecture is applied to define the structure for the formation flight. To study the pragmatic issues of the proposed formation flight controller, it is implemented into multiple micro air vehicles which are modeled by a... 

This paper addresses the effect of different optimization criteria for the control purpose of vehicle suspension. In the present study, active vibration control system for a 5 degree-of-freedom (DoF) pitch-plane suspension model with bounce and pitch motions is investigated. In the proposed vehicle model, the impact of the wheel-axle-brake assemblies' masses is also considered. The developed model is controlled using a fuzzy logic controller (FLC) to minimize the vibration of the driver's seat. The controller is designed to control the applied force to the seat. Furthermore, in order to determine the optimal value of fuzzy system parameters, genetic algorithm (GA) optimization search is used...