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For the coupling problems of looper tension and height control system of hot continuous rolling mil l, a robust control strategy based on decentralized control method was proposed. The integrated model of looper tension and height control system was established firstly. The looper height and tension control system was regarded as two independent systems, and the coupling between each other was regarded...
The paper studies the robust control problem of discrete-time systems with state saturation. First the paper introduces an ellipsoid and supposes that the invariant set of the system contains the ellipsoid. By using matrix norm theory we obtain one sufficient condition of the stability of the discrete-time system with state saturation. The attraction domain of the system is estimated. Then the paper...
The dynamical characteristics of hypersonic vehicles make them challenging to achieve the robust flight. The vehicle dynamics involve parametric uncertainties, serious coupling, nonlinearity, unmodeled uncertainties and external disturbances. A robust nonlinear controller is proposed consisting of a feedback linearization controller and a linear robust controller to restrain the effect of the multiple...
Robust velocity and height control problem is dealt with for hypersonic vehicles subject to highly nonlinearity and uncertainties. The linear robust controller design for nonlinear systems suffers from the conservation problem, because the nonlinear dynamics are considered as uncertainties. In this paper, a feedback linearization controller is firstly applied to achieve the dynamic decoupling of the...
This paper deals with the disturbance rejection problem in a repetitive control system (RCS) with time-varying uncertainties. The RCS is first described in the two-dimensional (2D) form. Next, an equivalent-input-disturbance (EID)-based estimator is incorporated into the 2D RCS to solve the problem of aperiodic disturbance rejection. Under this configuration of the system, while a periodic reference...
This paper presents robust PID (proportional integral derivative) controller tuning using genetic algorithm and small-gain approach for wastewater treatment. In operational terms, the main control objective is to maintain the concentration of the biomass directly proportional to the influent flow rate with the various disturbance compensation, noisy measurements and varying process model parameters...
This paper presents a new switching control approach for robust output feedback control of a class of discrete-time linear systems subject to polytopic time-varying uncertainties. The proposed robust switching controller, which stabilizes the closed-loop system with a pre-specified H∞ performance level, consists of a family of dynamic output feedback controllers (of an arbitrary state order) and a...
In this paper, the robust stabilization problem for a class of discrete-time uncertain nonlinear systems is investigated by using a neuro-optimal control strategy. The robust stabilization problem is converted into an optimal control problem under some proper conditions. Then, in order to deal with the transformed optimal control problem, the discrete-time generalized Hamilton-Jacobi-Bellman equation...
Unmodeled disturbances always exist in physical servo systems and degrade their tracking performance. In this paper, a practical method named robust control based on disturbance estimation is proposed and integrated for high-accuracy motion control of a dc motor. A finite-time disturbance observer (FTDO) for the unmodeled disturbances is designed and disturbance estimation is used to compensate the...
Modeling uncertainties and measurement noise in physical servo systems severely deteriorate their tracking performance. In this paper, an output feedback control strategy which integrates a discontinuous robust control with extended state observer via feed-forward cancellation technique is proposed for high precision motion control of a dc motor. The designed extended state observer can estimate the...
For the quadrotor unmanned aerial vehicle, a position tracking controller is developed using saturated robust integral of sign of error (RISE). The quadrotor dynamics are nonlinear and underactuated. Also, the dynamics are affected by added disturbance and uncertainty caused by ground effect. High gain controllers (such as RISE) can compensate for these effects but they do not consider the fact that...
In this paper, a modified version of composite nonlinear feedback (CNF) control method is proposed to achieve fast and accurate trajectory tracking for linear systems subject to input saturation and unknown disturbances. The basic idea is to incorporate a reference generator which constructs the target state vector corresponding with the trajectory reference signal, and an extended state observer...
Due to the ground effect, it is difficult for quadrotor to take off or land precisely. This paper presents a new ground effect model of quadrotor based on the Cheeseman's model for helicopter, and a ground effect compensator is introduced into the control system. Meanwhile by combining the proportional-integral-derivative (PID) control method and the robust compensation technique, a robust altitude...
The spacecraft attitude motion equations described by the Euler angles are expressed in vector form and viewed as two blocks, a kinematics block and a dynamics block. Based on Lyapunov stability theory, a robust dynamic surface control algorithm is designed for the nonlinear control system of attitude tracking of spacecraft in the presence of parameter uncertainty and external disturbances. Then,...
Even through being an effective approach to handle robustness, the single H∞ controller is challenging to meet strict performance requirement when the modeling mismatch is relatively large. This paper presents a supervisory method to enhance the robust stability and performance of H∞ control using a multiple model switching configuration. A new scheduling logic which selects the most proper controller...
During inertia phase of automatic transmission, slip velocity control is made worse due to uncertainty of valve dynamics and frictional coefficient. This paper proposes a design method of filter used for disturbance observer to overcome the issue. Small gain theorem and a mixed sensitivity problem are applied to robust design of the filter. Robustness of the slip velocity control is made clear through...
Load frequency control is an important measurement to ensure the safe and economical operation of power system. In this paper, by taking into account the random disturbances brought by the renewable energy resources, the robust load frequency control problem for interconnected power systems with time delay is considered in detail. Considering the signal transmission delay, two controller designing...
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