Current Issue : October - December Volume : 2020 Issue Number : 4 Articles : 5 Articles
This paper analyzes one kind of optimal control problem which is described by forward-backward stochastic differential equations with\nLevy process (FBSDEL).Wederive a necessary condition for the existence of the optimal control by means of spike variational technique,\nwhile the control domain is not necessarily convex. Simultaneously, we also get the maximum principle for this control system when\nthere are some initial and terminal state constraints. Finally, a financial example is discussed to illustrate the application of our result....
In this paper, a method of fault diagnosis (FD) and fault-tolerant tracking control (FTTC) is investigated for non-Gaussian\nnonlinear stochastic distribution control (SDC) systems with missing measurements.Thephenomenon of the randomly occurring\nmissing measurements is described as a Bernoulli process. The missing measurements during transmission are compensated with\nthe data successfully transmitted at the previous moment. The residual signal of the fault diagnosis observer is different from that\nof the general system. Using the integral of the error of the output probability density function (PDF) as the driving information,\nthe system state and fault can be estimated by an adaptive fault diagnosis observer. Then, a novel fault-tolerant tracking controller\nis designed based on a discrete-time 2-order sliding mode to make the post-fault PDF still track the target. Two simulated\nexamples are included to illustrate the effectiveness of the theoretical results....
Chaotification can be employed to weaken or eliminate the feature of line spectra of waterborne noise. The efficiency of this\nmethod lies on the use of small control. The analysis reveals that the critical control gain depends on the stiffness of vibration\nisolation systems. Thus, an isolation raft system based on quasi-zero-stiffness (QZS) property is proposed for line spectrum\nchaotification. A nonlinear time-delay controller is derived accordingly. Comparative analysis shows that the new approach allows\nmuch smaller control, and the intensity of line spectra is further reduced. Numerical simulations also indicate other advantages\nwith the introduction of QZS system into chaotification....
This manuscript addresses a novel output model predictive controller design for a\nrepresentative model of continuous stirred-tank reactor (CSTR) and axial dispersion reactor with\nrecycle. The underlying model takes the form of ODE-PDE in series and it is operated at an\nunstable point. The model predictive controller (MPC) design is explored to achieve optimal\nclosed-loop system stabilization and to account for naturally present input and state constraints.\nThe discrete representation of the system is obtained by application of the structure properties\n(stability, controllability and observability) preserving Cayley-Tustin discretization to the coupled\nsystem. The design of a discrete Luenberger observer is also considered to accomplish the output\nfeedback MPC realization. Finally, the simulations demonstrate the performance of the controller,\nindicating proper stabilization and constraints satisfaction in the closed loop....
Soil compaction is an important procedure of precision seeding operation. In this paper, a precise downforce control system based\non fuzzy PID was proposed in order to improve the quality of the soil compaction and the accuracy of setting working parameters.\nThe conventional mechanism of seeders for soil compaction was optimised. The compressing spring of the compaction\nmechanism was replaced by a linear motor, which is actively controlled to adjust downforce in real time. A force sensor was\nconnected in series with the linear motor to detect the actual downforce from a press wheel acting on soil. The detected downforce\nwas employed as feedback for the fuzzy PID model. A slave real-time control system was constructed by using an STM32\nmicrocontroller. A user interface was designed for the portable master computer system based on the ForLinx embedded platform\nto facilitate the setting of target downforce and display the actual downforce in real time. Meanwhile, it was able to adjust the\nsystem for different operating requirements, such as soil stiffness, moisture, and crop species. Experiments were conducted on a\nsoil bin, and the results indicated that the active control system has better performance than the conventional passive system in\ndownforce control. The downforce was stable with a variance less than 2.6% under different conditions, and it was 8.11% less than\nthe conventional passive system....
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