In this paper, a saturated PD based Fault Tolerant Control is proposed for a quadrotor suffering a severe fault in one of its actuators, on top of a new control scheme assuming the fault has been already detected by the system. Whenever a severe fault occurs in system, the PD control is reconfigured by adding relevant trirotor control equations to the control laws. To tune the optimal parameters of the controllers, a Particle Swarm Optimization algorithm (PSO) is used. The stability of the upgraded PD is proved by using Lyapunov theorem. Simulation Results with some induced disturbance demonstrated the effectiveness of the proposed controller in controlling the damaged quadrotor until it finishes its path. © 2017 IEEE.
Publication Date: 0
IEEE Transactions on Vehicular Technology (00189545)55pp. 1725-1730
Antilock braking systems (ABS) have been developed to improve vehicle control during sudden braking especially on slippery road surfaces. The objective of such control is to increase wheel tractive force in the desired direction while maintaining adequate vehicle stability and steerability and also reducing the vehicle stopping distance. In this paper, an optimized Fuzzy controller is proposed for antilock braking systems. The objective function is defined to maintain wheel slip to a desired level so that maximum wheel tractive force and maximum vehicle deceleration are obtained. All components of fuzzy system are optimized using genetic algorithms. The error based global optimization approach is used for fast convergence near optimum point. Simulation results show fast convergence and good performance of the controller for different road conditions. ©2005 IEEE.
This paper proposes an active disturbance rejection control (ADRC) method based on generalized proportional integral (GPI) observer to control of a biped robot while considering its complicated structure and possible disturbances. These observers are used to estimate time-varying disturbances and possible uncertainties. Generally, implying GPI observer on robotic systems is accompanied by a PD-controller in feedback, which is not efficient enough due to abrupt velocity changes of the biped in impact phase, and consequently, a higher level of input torque is required. Thus, applying the back-stepping technique to the mentioned method is suggested. In this study, a two-nested control loop is designed for a 3D biped robot. The back-stepping method with a GPI observer is used in the inner control loop to improve the custom method. Joint trajectories are designed by an offline method and modified by an online method in the outer loop to maintain the stability of the biped. The efficiency of the proposed control strategy is depicted for the biped in the presence of time-varying disturbances through MATLAB simulation. © 2019 IEEE.
Anti-lock braking systems (ABS) have been developed to reduce tendency for wheel lock and improve vehicle control during sudden braking especially on slippery road surfaces. The objective of such control is to increase wheel tractive force in the desired direction while maintaining adequate vehicle stability and steerability and also reducing the vehicle stopping distance. In this paper, a genetic-fuzzy ABS controller is designed. The objective function is defined to maintain wheel slip to a desired level so that maximum wheel tractive force and maximum vehicle deceleration are obtained. All components of the fuzzy system that is Takagi-Sugeno-Kang (TSK) type are obtained using a genetic algorithm. Simulation results show very good performance of the controller for different road conditions. © 2005 IEEE.
In this paper, the problem of Lyapunov Exponents (LEs) computation from chaotic time series based on Jacobian approach by using polynomial modelling is considered. The embedding dimension which is an important reconstruction parameter, is interpreted as the most suitable order of model. Based on a global polynomial model fitting to the given data, a novel criterion for selecting the suitable embedding dimension is presented. By considering this dimension as the model order, by evaluating the prediction error of different models, the best nonlinearity degree of polynomial model is estimated. This selected structure is used in each point of the reconstructed state space to model the system dynamics locally and calculate the Jacobian matrices which are used in QR factorization method in the LEs estimation. This procedure is also applied to multivariate time series to include information from other time series and resolve probable shortcoming of the univariate case. Finally, simulation results are presented for some well-known chaotic systems to show the effectiveness of the proposed methodology. © 2003 EUCA.
One of the main problems in the islanded microgrids is the frequency regulation. Moreover, there are several uncertainties and disturbances in the islanded microgrids that may lead to the instability. To solve this problem, this paper proposes the design of a multi-objective Linear Matrix Inequalities (LMIs) based regulator. It considers the LMI conditions in such a way that the design criterion holds. It also considers the disturbances, including solar radiation, wind speed, and load demand variations. With extracting microgrid state space model, it builds a framework to synthesize the controller. Next, it presents the mixed robust design criteria to set up the multi-objective function. The controller design process includes two steps: state feedback and observer designs. With considering weighing functions in the design process, it determines the optimal solution of the objective function. The obtained solution is the state feedback matrix, and it forms the controller by combining the state feedback matrix with a state observer. We have applied the designed controller to the islanded microgrid, and the effect of disturbances is evaluated together with parametric uncertainties. The proposed regulator is compared with the traditional PI method. The results show that the designed regulator has robust performance as well as robust stability. © 2017 IEEE.
This paper presents an analysis on electrolytic capacitor-less inverter and proposes a strategy for resonance suppression control for a DC-link voltage and input current in electrolytic capacitor-less inverter. The proposed electrolytic capacitor-less inverter can operate both in the motoring mode and regenerating mode owing to its inherent bidirectional power flow capability of the active front-end rectifier whose switching frequency is equal to the input line frequency. However, in the electrolytic capacitor-less inverter, the DC-link voltage is fluctuating with six times of the frequency of input three phase source due to its small DC link capacitance. Also, an input filter should be employed to remove the high frequency component generated by PWM inverter. By the input filter, the DC-link voltage can be resonant, and a specific resonance suppression control is required when the input line-to-line voltage is low and the demanded power is large. In this paper, a novel resonance suppression strategy is proposed for a stable operation of the electrolytic capacitor-less inverter. The experimental results show the effectiveness of proposed strategy. ©2009 IEEE.
