Considering the variations of inertia in real applications, an adaptive control scheme for the permanent-magnet synchronous motor speed-regulation system is proposed in this paper. First, a composite ...control method, i.e., the extended-state-observer (ESO)-based control method, is employed to ensure the performance of the closed-loop system. The ESO can estimate both the states and the disturbances simultaneously so that the composite speed controller can have a corresponding part to compensate for the disturbances. Then, considering the case of variations of load inertia, an adaptive control scheme is developed by analyzing the control performance relationship between the feedforward compensation gain and the system inertia. By using inertia identification techniques, a fuzzy-inferencer-based supervisor is designed to automatically tune the feedforward compensation gain according to the identified inertia. Simulation and experimental results both show that the proposed method achieves a better speed response in the presence of inertia variations.
The speed regulation problem for permanent magnet synchronous motor (PMSM) servo system is studied in this paper. In order to optimize the control performance of the PMSM servo system, the predictive ...functional control (PFC) method is introduced in the control design of speed loop. The PFC-based speed control design consists of two steps. A simplified model is employed to predict the future q -axis current of PMSM. Then, an optimal control law is obtained by minimizing a quadratic performance index. However, it is noted that the standard PFC method does not achieve a satisfying effect in the presence of strong disturbances. To this end, an improved PFC method, called the PFC+ESO method, is developed. It introduces extended state observer (ESO) to estimate the lumped disturbances and adds a feedforward compensation item based on the estimated disturbances to the PFC speed controller. Simulation and experiment comparisons are made for these PFC methods and proportional-integral method with antiwindup control method to verify the effectiveness of the proposed methods.
In this paper, finite-time position consensus and collision avoidance problems are investigated for multi-AUV (autonomous underwater vehicle) systems. First, based on the homogeneous control method, ...finite-time position consensus algorithms are proposed for both leaderless and leader–follower multi-AUV systems without considering collisions between the AUVs. Specifically, in the leader–follower case, a novel distributed finite-time observer is developed for the followers to estimate the leader’s velocity. Second, by constructing collision avoidance and connectivity maintenance functions, modified consensus algorithms containing corresponding gradient terms are presented for multi-AUV systems of both cases, which guarantee collision avoidance, connectivity maintenance, velocity matching, and consensus boundedness. Simulations demonstrate the effectiveness of the proposed control algorithms.
The attitude synchronization problem for a group of flexible spacecraft is discussed in this note. Meanwhile, the communication delay among these spacecraft is also considered. By combining the ...method of backstepping design with the finite-time control technique, a distributed delayed attitude control algorithm is proposed which is the neighbor-based design. Under the proposed control algorithm, it is shown that the attitude synchronization can be achieved asymptotically. Finally, an example is given to verify the efficiency of the proposed method.
This paper develops a sliding-mode control (SMC) approach for systems with mismatched uncertainties via a nonlinear disturbance observer (DOB). By designing a novel sliding surface based on the ...disturbance estimation, a DOB-based SMC method is developed in this paper to counteract the mismatched disturbance. The newly proposed method exhibits the following two attractive features. First, the switching gain is only required to be designed greater than the bound of the disturbance estimation error rather than that of the disturbance; thus, the chattering problem is substantially alleviated. Second, the proposed method retains its nominal performance, which means the proposed method acts the same as the baseline sliding-mode controller in the absence of uncertainties. Simulation results of both the numerical and application examples show that the proposed method exhibits much better control performance than the baseline SMC and the integral SMC (I-SMC) methods, such as reduced chattering and nominal performance recovery.
This technical note studies the finite-time consensus problem of leader-follower higher-order multi-agent systems with mismatched disturbances. To solve such a problem, by combining the non-singular ...terminal sliding-mode control (NTSMC) and disturbance observer based control (DOBC) methods together, a distributed active anti-disturbance cooperative control scheme is proposed. Firstly, to estimate the matched/mismatched disturbances of each follower, a finite-time disturbance observer is constructed. Secondly, by distributedly employing the mismatched disturbances estimates, integral-type non-singular terminal sliding-mode surfaces are designed for followers. Thirdly, distributed protocols are proposed based on the surfaces. In the presence of mismatched disturbances, these protocols achieve finite-time output consensus for the agents. Simulations validate the correctness and effectiveness of the proposed control scheme.
This note investigates the finite-time attitude control problems for a single spacecraft and multiple spacecraft. First of all, a finite-time controller is designed to solve finite-time attitude ...tracking problem for a single spacecraft. Rigorous proof shows that the desired attitude can be tracked in finite time in the absence of disturbances. In the presence of disturbances, the tracking errors can reach a region around the origin in finite time. Then, based on the neighbor rule, a distributed finite-time attitude control law is proposed for a group of spacecraft with a leader-follower architecture. Under the finite-time control law, the attitude synchronization can be achieved in finite time.
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•The sensitivity of different pollution sources to water quality indices is different.•The most effect factor on water quality was Shannon's Diversity Index (SDI).•The scale effects ...of different pollution sources are significantly different.•Land use pattern has a controlling effect on water quality indices.
Understanding the scale relationship between landscape pattern and water quality is of great significance for improving water pollution and guiding the rational planning of land use in watersheds. At present, most existing studies take the watershed as a whole to explore the scale relationship between landscape pattern and water quality. Research on different types of pollution sources is still lacking. According to the characteristics of the pollution source in the watershed, the study of the multiscale effects of landscape pattern of different pollution source areas on water quality will help better the understanding of the impact of the surrounding landscape on the water quality of rivers, which is very important for local river management. In this study, a typical plateau lake basin, the Fuxian Lake basin, is taken as the research area, and the scale relationship between the surface landscape pattern and water quality in different pollution sources is taken as the research object. The redundancy analysis and multiple regression modeling are used to explore the impact of landscape pattern on water quality. The results show that the key landscape metrics that affect water quality indices in different pollution source areas and at different scales are quite different. Shannon's diversity index (SDI) had a significant effect on total phosphorus (TP) across the entire watershed. In the urban region, SDI and the mean shape index (MSI) have the greatest impact on chemical oxygen demand (COD) at the sub-watershed scale. In the phosphorus mining region, the landscape metrics SDI, Shannon's evenness index (SEI), and patch cohesion index (COHES) have significant effects on water quality, especially on TP. In the farmland and village region, the other 7 landscape metrics excluding the number of patches (NumP) become the leading indicators affecting water quality at different scales, among which total nitrogen (TN) has a particularly significant influence. Overall, the factor with the greatest effect on water quality was SDI in different pollution source areas. In terms of the scale effect, the landscape pattern has the strongest effect on water quality changes in the urban and phosphorus mining regions at sub-watershed scales, while in the farmland and village region, 300 m and 500 m are the areas where the landscape pattern has the strongest effect on water quality. These findings can provide decisional support for improving the water quality of lakes and rivers from the perspective of sustainable landscape management.
Disturbance-observer-based control (DOBC) and related methods have been researched and applied in various industrial sectors in the last four decades. This survey, at first time, gives a systematic ...and comprehensive tutorial and summary on the existing disturbance/uncertainty estimation and attenuation techniques, most notably, DOBC, active disturbance rejection control, disturbance accommodation control, and composite hierarchical antidisturbance control. In all of these methods, disturbance and uncertainty are, in general, lumped together, and an observation mechanism is employed to estimate the total disturbance. This paper first reviews a number of widely used linear and nonlinear disturbance/uncertainty estimation techniques and then discusses and compares various compensation techniques and the procedures of integrating disturbance/uncertainty compensation with a (predesigned) linear/nonlinear controller. It also provides concise tutorials of the main methods in this area with clear descriptions of their features. The application of this group of methods in various industrial sections is reviewed, with emphasis on the commercialization of some algorithms. The survey is ended with the discussion of future directions.
In this paper, we discuss the finite-time consensus problem for leaderless and leader–follower multi-agent systems with external disturbances. Based on the finite-time control technique, continuous ...distributed control algorithms are designed for these agents described by double integrators. Firstly, for the leaderless multi-agent systems, it is shown that the states of all agents can reach a consensus in finite time in the absence of disturbances. In the presence of disturbances, the steady-state errors of any two agents can reach a region in finite time. Secondly, for the leader–follower multi-agent systems, finite-time consensus algorithms are also designed based on distributed finite-time observers. Rigorous proof is given by using Lyapunov theory and graph theory. Finally, one example is employed to verify the efficiency of the proposed method.
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