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This paper addresses consensus tracking problem for multi-agent linear systems subject to exogenous disturbances generated from heterogeneous exosystems. Firstly, by using the dynamic gain technique, a nonlinear disturbance observer is presented to estimate the disturbances generated from heterogeneous nonlinear exosystems. Secondly, with the help of this nonlinear disturbance observer, a distributed...
The purpose of the paper is to propose a new control scheme in active front steering (AFS) for vehicle stability using disturbance observer method. In the paper, the ideal yaw rate can be calculated on the linear two-degrees-of-freedom vehicle model. In addition, the actual sideslip angle can also be estimated by using a state observer. Based on this, two kinds of baseline AFS controllers are proposed...
In this paper, the design problem of sliding mode observer is addressed for a class of linear continuous-time systems with actuator faults and limited data communication. A new descriptor sliding mode observer approach is developed to solve this design issue, where a discontinuous input is constructed to reject actuator faults. It is proved that the lower bound on the density of the quantizer is 1...
This paper focuses on the transition flight control for a small tilt rotor unmanned aerial vehicle (UAV). Aiming at the longitudinal model of a tilt rotor UAV, a novel sliding mode control (SMC) method is proposed to guarantee that the states converge to the desired sliding surfaces in finite time. Moreover, extended state observers (ESOs) are provided to enhance the system's robustness to the uncertainties...
Aiming at the time-varying load torque disturbance in the vibration displacement system of continuous casting mold driven by servo motor, an extended state observer (ESO) based backstepping sliding mode control method is proposed. Firstly, a mapping function is established to deal with the non-uniqueness of the nonlinear inverse relationship from eccentric shaft angle to mold displacement. Secondly,...
The tail-sitter unmanned aerial vehicle (UAV) is a kind of vertical take-off and landing (VTOL) UAV which has the merits of both fixed-wing and rotary-wing. The tail-sitter UAV in this paper has three flight modes. The most important stage is the transition stage. The model for the transition stage is established and a transition flight strategy is constructed so that the UAV can change vertical takeoff...
This paper develops a sliding mode control (SMC) approach for a class of uncertain nonlinear systems with unmatched uncertainties/disturbances. The newly proposed method is based on a novel fixed-time convergent sliding mode disturbance observer which can estimate the unmatched disturbance in a fixed time (time whose upper estimate is independent of the initial conditions). By designing a novel sliding...
An active disturbance rejection controller (ADRC) is designed and originally implemented on a real torsional plant. The torsional plant resembles the dynamics of a rotational system. Due to mass imbalance, centrifugal imbalance, and the non-coincidence between the principal and geometric axes of a rotating disc, the system parameters of this torsional plant are varying constantly. In addition, an...
The problem of unknown input reconstruction for nonlinear dynamic system is addressed in this paper. A system inversion based method as well as a combination method which integrates sliding mode observer with system inversion is implemented for achieving this purpose on a Hex reactor system. The second order sliding mode observer is considered to exactly estimate the successive derivatives of the...
The problem of delay-dependent observer-based robustly passive control is addressed for neutral type descriptor Markov jump systems with time-varying delays. The parameter uncertainties of the system are assumed unknown and norm-bounded. Using Lyapunov-Krasovskii functional method and weighted matrix, a delay-dependent robustly passive condition for closed-loop system is given. Then, the sufficient...
This paper concerns disturbance rejection for a repetitive-control system (RCS) with unknown time-varying uncertainties and nonlinearity. The design of the RCS is based on the concept of equivalent input disturbance (EID). First, an EID estimator is constructed through a state observer with dynamic coefficient matrix that effectively estimates the total effect of the uncertainties and nonlinearity...
For a class of linear systems with external smooth disturbances, control design is considered to attenuate the effect of the disturbances on the outputs of the systems. To deal with the unmatched disturbances, a disturbance-dependent state transformation is introduced, so that the transformed disturbances satisfy the matching condition in the new state coordinates, and therefore we design controllers...
For a class of fractional-order systems with uncertainty and disturbance, sliding mode control method is presented based on disturbance observer. To estimate the compound disturbance, extended fractional-order disturbance observer is proposed, which can compensate more extensive disturbances than vanishing disturbances. By using the sliding mode theory, fractional-order integral-type sliding mode...
Time-varying formation tracking problems for high-order nonlinear multi-agent systems are investigated by using a distributed observer-based method. Different from the previous work, the states of followers form a predefined time-varying formation while tracking the states of the leader with unknown but bounded control input. Besides, the dynamics of each agent is high-order and has nonlinearity....
In this paper we reinvestigate the distributed state observer for a spatially interconnected system composed of many subsystems interacting with each other. Several LMI based conditions are provided which are less conservative than or complement with the existed ones. These conditions utilize effectively the block-diagonal characteristic of system parameters and the sparseness of subsystem connection...
In this paper, the consensus for a class of nonlinear heterogeneous multi-agent systems (MAS) subject to unknown external disturbances is investigated. Firstly, the neighbor-based distributed finite-time observers are proposed for the followers to estimate the position and velocity of the leader. Then, a novel distributed adaptive control laws is designed by means of linear sliding mode (LSM). One...
An observer-based fault-tolerant control scheme is developed for the attitude stabilization control of the rigid spacecraft in the presence of constants and time-varying actuator faults as well as external disturbances. The proposed iterative learning observer employs a learning mechanism to estimate the fault torque values combined with external disturbances, furthermore, the sign function and the...
This paper deals with sensorless vector control of induction motor (IM) based on model reference adaptive system (MRAS) theory and sliding mode technique. An adaptive-gain supertwisting (ASTW) sliding mode speed controller is designed to provide good speed tracking performance in the presence of load torque variation. A stator current and rotor flux sliding mode observer (SMO) is designed, which is...
For polynomial fuzzy system with time delay, this paper presents a new polynomial fuzzy observer design approach via sum of squares approach. We propose an algorithm to design polynomial fuzzy controller and observer satisfying the stability of the overall control system in addition to converging state estimation error to zero. The stability analysis for the augmented systems of the time-delay polynomial...
Electric Power Assisted Bicycle (EPAC) is becoming the transport and fitness tools that people pursue because of its green, healthy and economical characteristics. Compared to the conventional electric bike, EPAC not only reduces the burden on the rider, but also maintains the original bicycle characteristics. Nowadays, there is few study of the control approach adaptive to road slope and load for...
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