Sharif Digital Repository

The control of a brachiation robot has been the primary objective of this study. A brachiating robot is a type of a mobile arm that is capable of moving from branch to branch similar to a long-armed ape. In this paper, to minimize the actuator work, Pontryagin's minimum principle was used to obtain the optimal trajectories for two different problems. The first problem considers “brachiation between fixed branches with different distance and height,” whereas the second problem deals with the “brachiating and catching of a moving target branch”. Theoretical results show that the control effort in the proposed method is reduced by 25% in comparison with the “target dynamics” method which was... 

Human running can be stabilized in a wide range of speeds by automatically adjusting muscular properties of leg and torso. It is known that fast locomotion dynamics can be approximated by a spring loaded inverted pendulum (SLIP) system, in which leg is replaced by a single spring connecting body mass to ground. Taking advantage of the inherent stability of SLIP model, a hybrid control strategy is developed that guarantees a stable biped locomotion in sagittal plane. In the presented approach, nonlinear control methods are applied to synchronize the biped dynamics and the spring-mass dynamics. As the biped center of mass follows the mass of the mass-spring model, the whole biped performs a... 

In this paper, a novel robust adaptive control method is proposed for controlling the Lorenz chaotic attractor. A new backstepping controller for the Lorenz system based on the Lyapunov stability theorem is proposed to overcome the singularity problem that appeared in using the typical backstepping control method. By exploiting the property of the system, the resulting controller is shown to be singularity free and the closed loop system is globally stable. Due to unavailability of system states measurement in practice, the controller is selected such that only one system state is needed. To overcome the problem of parameter uncertainty, an additional term to Lyapunov function is added and... 

The preparation of microcapsules containing perphenazine by solvent evaporation using ethyl cellulose is described. The microparticles are formed after solvent evaporation and polymer precipitation. The drug was dissolved in a polymer solution and emulsified into an aqueous phase to form microcapsules. To study the effects on particle size, encapsulation efficiency and morphology, three different molecular weights of ethyl cellulose (Mw=47000, 71000 and 99000) were used. Covalent bonding of drugs to polymers via hydrolytically or enzymatically cleavable covalent bond was achieved for sustained drug delivery. The release rate of perphenazine from these systems was investigated  

In the past decade, distribution network operators have been broadly engrossed toward automated distribution networks. The operators acknowledge network automation as an efficient investment toward a better service reliability. This paper aims to provide a new long-term cost/benefit analysis for an optimal level of distribution network automation. In the analysis, reduction in customer outage cost is considered as the benefit of implementing automation systems with capital investment, and annual operation and maintenance costs. In the Finnish regulation model, there is a special incentive based on customer outage cost reduction. As the main contribution of this paper, the impact of earth... 

Societal concerns over global warming issues and dependence on fossil fuels have caused the vehicle market share of plug-in hybrid electric vehicles (PHEVs) to grow. A large penetration of PHEVs, however, would likely put higher stress on power systems. To lessen the PHEVs' harmful impacts on the distribution grid, this paper proposes a two-stage charging control strategy modeled on a renewable-based energy hub. In the first stage, a home-based charging control method is formulated in which the charging cost of PHEVs is considered as an objective. Running this procedure by PHEV schedulers in houses, in the second stage of the proposed strategy, the PHEV coordinator agent (PCA) applies a... 

Trying to find the most efficient and cost-effective decisions on the maintenance of different component types in power distribution systems is an increasingly challenging concern largely driven by the current financial constraints in distribution utilities worldwide. In regard to deal with this challenge, the paper presents a practical application of the Delphi method and the Modified Analytical Hierarchical Process (MAHP) that can be used to find the most critical component types of the system in order to assist in accordingly allocating the available maintenance budget. The proposed approach involves the experience and knowledge held by experts and the historical empirical performance... 

This paper investigates the main features of the PHEV centralized and decentralized charging control mechanisms, their requirements and also impacts on distribution system performance. A home-based charging control scenario as well as a coordinated charging control algorithm for the charging management of PHEVs is devised in this paper. Both the owner preferences and system operator concerns are taken into consideration in an optimization-based framework. The total network losses and charging costs are set as the constraints to the proposed optimization approach. Various aspects of the two mechanisms are discussed and comprehensively compared by their application on the IEEE 34-bus test... 

Demand response (DR) as a state-of-the-art program is accommodated in the energy efficiency contexts of the smart grid. Lack of the customer knowledge about how to respond to the time-differentiated tariffs and offered controlling signals is the major obstacle in the way of broad DR implementing. As a solution, an optimization method, namely load control (LC), is proposed to automatically control the on/off status of the responsive appliances in a smart home. This paper focuses on the direct load control (DLC) program in the category of incentive-based DR programs. LC is extended to consider inconvenience cost of the DLC implementation for DLC program participants. Outputs of the extended LC... 

Although demand response (DR) potentially brings miscellaneous advantages, it is currently faced with challenges in its implementation due to customers' difficulty in manually responding to the time-varying prices. This paper presents an optimal and automatic residential load commitment (LC) framework to achieve the household minimum payment. Problem decision variables are the operating status of responsive appliances and charging/discharging cycles of battery storage and plug-in hybrid electric vehicles (PHEVs). Storage capability in residential centers provide the customers with this opportunity to not only supply the local demand during the high price hours but also sell the energy back... 

Monitoring/control infrastructures are often assumed to be fully reliable in power system reliability studies. However, recent investigations on blackouts have revealed the crucial impacts of monitoring/control system malfunctions. This paper addresses the impact of situational awareness and controllability on power system reliability assessment. A methodology is proposed to simulate a situation in which a limitation of either or both monitoring and control functions could spread the consequence of power system events throughout the grid. It is assumed that the monitoring/control infrastructure is based on a wide-area measurement system (WAMS). While the proposed methodology is applicable to... 

Plug-in hybrid electric vehicle (PHEV) technology provides one of the most promising solutions to tackle the threatening challenges such as air pollution in urban areas. Dramatic increases in the number of PHEVs could have major impacts on power system operations because of their high electricity demand. From the distribution system operator facet, distribution system congestion during PHEVs charging is an economic and security concern. It is, therefore, necessary to investigate the effects of widespread using of PHEVs on the performance of distribution networks. In this paper, PHEV characteristics are exactly studied and a comprehensive model for investigation of PHEV impacts is achieved.... 

The deployment of flexible ac transmission system (FACTS) devices, despite miscellaneous benefits and applications, has been restricted mainly due to their large investment costs. Accordingly, the notion of distributed FACTS (D-FACTS) was recently proposed. Distributed static series compensators (DSSCs), as a new member of D-FACTS, are directly clamped to conductors of transmission lines. The possibility of controlling the compensation rate of DSSCs from the control center affords the active control of network power flow. This paper presents a comprehensive reliability model for the DSSC. The model is then reduced and a state-space representation is extracted for a transmission line with a... 

This paper discusses various aspects of unified power flow controller (UPFC) control modes and settings and evaluates their impacts on the power system reliability. UPFC is the most versatile flexible ac transmission system device ever applied to improve the power system operation and delivery. It can control various power system parameters, such as bus voltages and line flows. The impact of UPFC control modes and settings on the power system reliability has not been addressed sufficiently yet. A power injection model is used to represent UPFC and a comprehensive method is proposed to select the optimal UPFC control mode and settings. The proposed method applies the results of a contingency... 

In this paper, the tip tracking control problem of a Timoshenko micro-cantilever beam is investigated. The beam is actuated by a piezoelectric layer laminated on one side of the beam. Dynamic equations of the beam and piezoelectric layer are found using the Hamilton principle. By employing the Galerkin projection method, state space representation of the system is derived. Then, a cascade control loop is used for tracking control of the beam's tip. The cascade control structure consists of an inner loop stabilizer and an outer loop proportional-integral-derivative controller. The stabilizer has a linear feedback form whose states are obtained through a linear observer which is based on the... 

In this study tracking problem of tip of a micro cantilever, actuated by electrostatic, is investigated. Dynamic model of the system is a PDE. Using electrostatic actuation.introduced significant nonlinearity in dynamic model of the system. Control goals are achieved by means of backstepping for SI and feedback linearization for MI system. Performance of control system is inspected for some assumptions and simplifications. The results are in according to numerical simulations  

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... 

The taping mode Atomic Force Microscopic (T-AFM) can be properly described by a sinusoidal excitation of its base and nonlinear potential interaction with sample. Thus the cantilever may cause chaotic behavior which decreases the performance of the sample topography. In this paper a nonlinear delayed feedback control.is proposed to control.chaos in a single mode approximation of a T-AFM system. Assuming model parameters uncertainties, the first order Unstable Periodic Orbits (UPOs) of the system is stabilized using the sliding nonlinear delayed feedback control. The effectiveness of the presented methods is numerically verified and the results show the high performance of the control.er  

The taping mode Atomic Force Microscopic (T-AFM) can be assumed as a cantilever beam which its base is excited by a sinusoidal force and nonlinear potential interaction with sample. Thus the cantilever may cause chaotic behavior which decreases the performance of the sample topography. In order to modeling, using the galerkin method, the PDE equation is reduced to a single ODE equation which properly describing the continuous beam. In this paper a nonlinear delayed feedback control.is proposed to control.chaos in T-AFM system. Assuming model parameters uncertainties, the first order Unstable Periodic Orbits (UPOs) of the system is stabilized using the sliding nonlinear delayed feedback... 

In this paper, a new approach for controlling the sway angle of the load in trolley cranes is presented which is based on the flexibility of the cable and variation of its length by the time. The crane dynamics has been described by hybrid PDE and ODE equations which uses the PDE as the equations of motion for the flexible cable and ODE for those of the trolley and the load. The purpose of the controller is to transport the load to the desired position and to eliminate its sway angle at the destination. The control law is based on the Lyapunov's second method. The efficiency of the proposed controller is demonstrated via various simulations