Adaptive feedforward and feedback control schemes for sliding mode controlled power converters

For the sour water strippers in petroleum refinery plants, three prediction models were developed first, including the estimators of sour water feed concentrations using convenient online measurements, the minimum reboiler duty and the corresponding internal temperature at a specific location (Tstage,29). Feedforward control schemes were developed based on these prediction models. Four categories of control schemes, including feedforward, feedback, feedback with external reset, and feedforward-feedback, were proposed and evaluated by the rigorous dynamic simulation model of the sour water stripper for their dynamic responses to the sour water feed stream disturbances. The comparison of control performance, in terms of the settling time, integrated absolute error (IAE) of the NH3 concentration of the stripped sour water and IAE of the specific reboiler duty, reveals that FFT (feedforward control of Tstage,29) and FBA-DT3 (feedback control with 3 min concentration measurement delay) are the best control schemes. The second-best control scheme is FBAT (cascade feedback control of concentration with temperature).

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A computationally efficient adaptive robust control scheme for a quad-rotor transporting cable-suspended payloads

Proceedings of the Institution of Mechanical Engineers Part G Journal of Aerospace Engineering ◽

10.1177/09544100211013617 ◽

2021 ◽

pp. 095441002110136

Author(s):

Nasim Ullah ◽

Irfan Sami ◽

Wang Shaoping ◽

Hamid Mukhtar ◽

Xingjian Wang ◽

...

Keyword(s):

Robust Control ◽

Fractional Order ◽

Sliding Mode ◽

Adaptive Robust Control ◽

Computationally Efficient ◽

Control Scheme ◽

Control Schemes ◽

Adaptive Laws ◽

Unknown Disturbances ◽

The Stability

This article proposes a computationally efficient adaptive robust control scheme for a quad-rotor with cable-suspended payloads. Motion of payload introduces unknown disturbances that affect the performance of the quad-rotor controlled with conventional schemes, thus novel adaptive robust controllers with both integer- and fractional-order dynamics are proposed for the trajectory tracking of quad-rotor with cable-suspended payload. The disturbances acting on quad-rotor due to the payload motion are estimated by utilizing adaptive laws derived from integer- and fractional-order Lyapunov functions. The stability of the proposed control systems is guaranteed using integer- and fractional-order Lyapunov theorems. Overall, three variants of the control schemes, namely adaptive fractional-order sliding mode (AFSMC), adaptive sliding mode (ASMC), and classical Sliding mode controllers (SMC)s) are tested using processor in the loop experiments, and based on the two performance indicators, namely robustness and computational resource utilization, the best control scheme is evaluated. From the results presented, it is verified that ASMC scheme exhibits comparable robustness as of SMC and AFSMC, while it utilizes less sources as compared to AFSMC.

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Input–output linearization minimum sliding-mode error feedback control for spacecraft formation with large perturbations

Proceedings of the Institution of Mechanical Engineers Part G Journal of Aerospace Engineering ◽

10.1177/0954410014533674 ◽

2014 ◽

Vol 229 (2) ◽

pp. 352-368 ◽

Cited By ~ 6

Author(s):

Lu Cao ◽

Xiaoqian Chen

Keyword(s):

Feedback Control ◽

Sliding Mode ◽

Error Feedback ◽

Input Output ◽

Spacecraft Formation ◽

Input Output Linearization

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Model-Based Design Approach to Improve Performance Characteristics of Hydrostatic Bearing Using Multivariable Optimization

Mathematics ◽

10.3390/math9040388 ◽

2021 ◽

Vol 9 (4) ◽

pp. 388

Author(s):

Waheed Ur Rehman ◽

Xinhua Wang ◽

Yiqi Cheng ◽

Yingchun Chen ◽

Hasan Shahzad ◽

...

Keyword(s):

Mathematical Model ◽

Feedback Control ◽

External Load ◽

Sliding Mode ◽

Feedforward Control ◽

Spindle Speed ◽

Performance Criteria ◽

Model Based ◽

Hydrostatic Bearings ◽

Robust Control Design

Research in the field of tribo-mechatronics has been gaining popularity in recent decades. The objective of the current research is to improve static/dynamics characteristics of hydrostatic bearings. Hydrostatic bearings always work in harsh environmental conditions that effect their performance, and which may even result in their failure. The current research proposes a mathematical model-based system for hydrostatic bearings that helps to improve its static/dynamic characteristics under varying conditions of performance-influencing variables such as temperature, spindle speed, external load, and clearance gap. To achieve these objectives, the capillary restrictors are replaced with servo valves, and a mathematical model is developed along with robust control design systems. The control system consists of feedforward and feedback control techniques that have not been applied before for hydrostatic bearings in the published literature. The feedforward control tries to remove a disturbance before it enters the system while feedback control achieves the objective of disturbance rejection and improves steady-state characteristics. The feedforward control is a trajectory-based controller and the feedback controller is a sliding mode controller with a PID sliding surface. The particle swarm optimization algorithm is used to tune the 6-dimensional vector of the tuning parameters with multi-objective performance criteria. Numerical investigations have been carried out to check the performance of the proposed system under varying conditions of viscosity, clearance gap, external load and the spindle speed. The comparison of our results with the published literature shows the effectiveness of the proposed system.

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