High purity distillation processes have been widely used in the chemical industry. These processes have unique characteristics including higher order, nonlinearity, strong coupling, and time delay. In order to overcome these control issues, an active disturbance rejection generalized predictive control strategy is designed for the distillation column with time delay. The strategy combines the structures of both active disturbance rejection control and generalized predictive control. A delayed designed extended state observer can estimate the model uncertainty and external disturbance, and a non‐incremental generalized predictive control is proposed to deal with the integrators with time delay. Therefore, it rejects disturbances well and has the capability of overcoming time delay. The computation load is also less than the generalized predictive control. In the simulation experiments, the proposed strategy is compared with robust control and model predictive control. The results illustrate that the proposed control strategy has improved robustness performance in dealing with model uncertainties, various disturbances, and time delay.
As an organic piezoelectric material, polyvinylidene fluoride (PVDF) can be utilized to fabricate thin film with high mechanical properties, and this film can be used to form flapping wing membrane. This type of wing with piezoelectric effect can solve the problems of the flight conditions measurement of flapping-wing micro aerial vehicles (FMAVs) in practical flapping flight. This study focuses on analysing the voltage outputs generated by PVDF membrane, and proposes two output voltage signal characteristics that can be used to deduce the flight conditions of FMAV, i.e. the voltage wave scale and voltage wave phase difference. The linear plate theory and unsteady aerodynamics coupling with piezoelectric equation are adopted to calculated the voltages generated by inertia and aerodynamic forces. The reasons and applications of scale and phase difference are analysed and discussed, and practical examples are demonstrated to illustrate specific impacts on these two signals.
Energy harvesting from aeroelastic response tends to have a wide application prospect, especially for small-scale unmanned aerial vehicles. Gusts encountered in flight can be treated as a potential source for sustainable energy supply. The plate model is more likely to describe a low aspect ratio, thin plate wing structure. In this paper, the Von Kármán plate theory and 3D doublet lattice method, coupled with a piezoelectric equation, are used to build a linear state-space equation. Under the load of “one-minus-cosine” discrete gust, the effects of flow speed and gust amplitude, thickness of piezoelectric ceramic transducer (PZTs) layers, and mounted load resistance are investigated. Results reveal that the PZTs layers on the wing root of the leading edge can obtain the highest electrical parameters. The flow velocity, thickness of the PZTs layers and load resistance are used to optimize energy harvesting data.
The jet pipe electro-hydraulic servo valve is a typical two-stage flow control servo valve, its static and dynamic characteristics are analyzed in this paper. The interaction of the mechatronic and hydraulic system is considered by multidomain simulation tool, the all key parameters are tunable and this provides the optimal possibility to develop a high-performance jet pipe electro-hydraulic servo valve.
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