Showing papers by "Mahdi Baradarannia published in 2016"

Leader-Follower Fixed-Time Consensus for Multi-agent Systems with Heterogeneous Non-linear Inherent Dynamics

Abstract: In this paper the leader-follower fixed-time consensus of multi agent systems with non-linear inherent dynamics is investigated. The non-linear inherent dynamics for followers and leader are supposed to be different. A distributed control protocol is proposed based on fixed-time consensus and it is shown that the proposed method solves leader-following fixed-time consensus. Finally, simulations are performed to show the efficiency of the theoretical results.

Time Optimal Control and Switching Curve Analysis for Caputo Fractional Systems

Abstract: In this paper we present a method for fractional time optimal control problems in terms of Caputo fractional derivatives. The studies up to now are about systems in terms of Riemann-Liouville fractional derivatives. But in this paper we investigated Caputo fractional systems. Firstly, by utilizing matrix approach method to discrete fractional derivatives, fractional Caputo derivative is solved. Then, the original problem is solved by traditional optimal problem solvers. Finally, time optimal problem is studied for a double fractional integrator and a method for obtaining switching curve has presented.

Rigid spacecraft attitude regulation with delayed feedback and actuator faults

Abstract: The work presented in this paper discusses time delay compensation of a rigid spacecraft with faulty actuators. The proposed method consists of a nominal controller and an extended state observer. Based on the backstepping method, the nominal control is designed to stabilize the spacecraft in the presence of delayed inputs. Then, the discrepancy between the nominal plant and real system which is influenced by faulty actuators, model uncertainties, and external disturbances is estimated by the extended state observer and actively compensated. The proposed controller does not require exact knowledge of delay, actuator faults and disturbances. By adjusting controller parameters, using the Lyapunov-krasovski method and properties of modified Rodrigues parameters, it is proved that the investigated control scheme can stabilize the system with respect to a small neighborhood of the origin. Numerical simulation results demonstrate that the acceptable performance of the controlled system is guaranteed in the presence of retreated inputs, the considered faults are tolerated and disturbances are rejected.

Vibration Attenuation of Nonlinear Hysteretic Structures with Fully Unknown Parameters

Abstract: Natural hazards such as earthquakes have threatened the life of human beings during the history.As a consequence, the vibration mitigation of structures has caught great importance. Activecontrol of structures is one of the rapidly emerging areas in the concept of structural control. Thispaper presents a control method to deal with this subject when the dynamics of the structure ishysteretic and the parameters of the structure contain uncertainties. The hysteresis behavior of thestructure is modeled using Bouc-Wen equation and the uncertainty is considered in its parameters.For control purpose, sliding mode method and its adaptive version are used. The salient point ofadaptive sliding mode technique is that it does not use the uncertainty bounds in its controller; thisis correspondent to the fact that the estimation of the structural parameters may not be exact. Theefficiency of the proposed method is shown with a simulation.