Observer-based Backstepping Control Research Articles

Observer-Based Backstepping Controller for Microalgae Cultivation

Microalgae are microscopic plants that exist in an aquatic environment. They are involved in the production of high value compounds and also have applications in energy production. In this work, the regulation of biomass concentration in a bioreactor is investigated by using an observer-based backstepping control approach. The process is controlled to operate in a constant biomass concentration mode, in order to maintain the culture at a desired concentration and to sustain high biomass production levels. Combined with the backstepping controller, a nonlinear Lipschitz observer is proposed. On the basis of the Droop model, which describes the dynamic behavior of the microalgae process and based on the biomass measurements, the stability of the state error dynamics can be guaranteed. Finally, simulations and comparisons with a PI controller are developed to show the performance of the nonlinear observer-based controller in set point tracking and load rejection in the presence of parameter uncertainties.

Observer-based backstepping control of linear stepping motor

This paper introduces an observer-based control approach for linear stepping motor (LSM) drive systems. The nonlinear motor dynamics is addressed in the backstepping control framework. Based on this model, a systematic analysis and design algorithm is developed to deal with stabilization and trajectory tracking of linear stepping motor systems. Moreover, to broaden the application range, the backstepping control method is extended to the output feedback control scheme. With simply measuring mover position, an observer-based backstepping controller is constructed to ensure satisfactory performance. In contrast to the conventional current regulated control strategy, this investigation considers a voltage-controlled pulse-width modulation (PWM) strategy with a complete theoretic exploration. The numerical simulations and experimental results illustrate the correctness and effectiveness of proposed approach.

Adaptive interconnected observer-based backstepping control design for sensorless induction motor

In this paper, an observer-based controller scheme is designed to robustly drive a sensorless Induction Motor (IM) even for the case of low frequencies with unknown load torque. Combining the field oriented control strategy with the backstepping control method, we introduce additional integral terms to improve the robustness properties of the controller in spite of uncertainties and perturbations. The estimation of the fluxes, the speed, the load torque and moreover the stator resistance is given by an adaptive interconnected observer. The practical stability of the proposed observer–controller scheme is proved. Finally, some experimental test results are given on the framework of a specific sensorless induction motor benchmark.

Observer-based backstepping control of the half-direct permanent magnet wind power generation system

In this paper, an observer-based backstepping controller is presented for the half-direct permanent magnet wind power generation system. The technology of backstepping is introduced to design the controller for maximum power point tracking at the operation region with low and moderate wind, and the high-gain observer is designed to estimate the unmeasurable variables needed for the controller design. Moreover, a switching mechanism is proposed, in which an online rotational speed is defined for the startup-to-grid-connected switch of the half-direct permanent magnet wind power generation system. Then, the stability of the designed closed-loop controlled system is analysed, based on the Lyapunov asymptotical stability theory. Simulation results are presented to show the efficiency of the proposed control law.

Observer-based backstepping force control of an electrohydraulic actuator

A backstepping approach is used in this paper to design a nonlinear controller for force control of a single-rod electrohydraulic actuator. The control design guarantees the convergence of the tracking error. The implementation of the control design requires system states for feedback, but in this case only the force output is available. To overcome this problem, a PI observer is used to estimate the states of the system. Experimental results have illustrated the success of the observer-based backstepping controller. The results are also compared to those obtained with conventional P and PI controllers. It can be shown that the observer-based backstepping controller has a relatively better tracking performance.

A New Flux Observer Design for Backstepping Controls of Induction Motors

A new observer for estimation of rotor fluxes is proposed to improve traditional backstepping controls of AC induction motors. The estimated torque and flux tracking errors are added to the observation. The new observer-based backstepping control guarantees asymptotic convergence to zero of both position and flux tracking errors, and exhibits less sensitivity to variation of rotor resistance. Simulation and experimental results verify the proposed approach.