Cascade controllers design based on model matching in frequency domain for stable and integrating processes with time delay

2022 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Mohd Atif Siddiqui ◽  
Md Nishat Anwar ◽  
Shahedul Haque Laskar
Keyword(s):  
Time Delay ◽  
Frequency Domain ◽  
Disturbance Rejection ◽  
Low Frequency ◽  
Cascade Control ◽  
Model Matching ◽  
Content Type ◽  
Proportional Integral ◽  
Load Disturbance ◽  
Wide Range

Purpose This paper aims to present an efficient and simplified proportional-integral/proportional-integral and derivative controller design method for the higher-order stable and integrating processes with time delay in the cascade control structure (CCS). Design/methodology/approach Two approaches based on model matching in the frequency domain have been proposed for tuning the controllers of the CCS. The first approach is based on achieving the desired load disturbance rejection performance, whereas the second approach is proposed to achieve the desired setpoint performance. In both the approaches, matching between the desired model and the closed-loop system with the controller is done at a low-frequency point. Model matching at low-frequency points yields a linear algebraic equation and the solution to these equations yields the controller parameters. Findings Simulations have been conducted on several examples covering high order stable, integrating, double integrating processes with time delay and nonlinear continuous stirred tank reactor. The performance of the proposed scheme has been compared with recently reported work having modified cascade control configurations, sliding mode control, model predictive control and fractional order control. The performance of both the proposed schemes is either better or comparable with the recently reported methods. However, the proposed method based on desired load disturbance rejection performance outperforms among all these schemes. Originality/value The main advantages of the proposed approaches are that they are directly applicable to any order processes, as they are free from time delay approximation and plant order reduction. In addition to this, the proposed schemes are capable of handling a wide range of different dynamical processes in a unified way.

Cascade control for heterogeneous multirotor UAS

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Ayaz Ahmed Hoshu ◽  
Liuping Wang ◽  
Alex Fisher ◽  
Abdul Sattar
Keyword(s):  
Control System ◽  
Disturbance Rejection ◽  
Unmanned Aircraft ◽  
Cascade Control ◽  
Underactuated System ◽  
Content Type ◽  
Control Approach ◽  
Robust Control System ◽  
And Control ◽  
Stable Control

PurposeDespite of the numerous characteristics of the multirotor unmanned aircraft systems (UASs), they have been termed as less energy-efficient compared to fixed-wing and helicopter counterparts. The purpose of this paper is to explore a more efficient multirotor configuration and to provide the robust and stable control system for it.Design/methodology/approachA heterogeneous multirotor configuration is explored in this paper, which employs a large rotor at the centre to provide majority of lift and three small tilted booms rotors to provide the control. Design provides the combined characteristics of both quadcopters and helicopters in a single UAS configuration, providing endurance of helicopters keeping the manoeuvrability, simplicity and control of quadcopters. In this paper, rotational as well as translational dynamics of the multirotor are explored. Cascade control system is designed to provide an effective solution to control the attitude, altitude and position of the rotorcraft.FindingsOne of the challenging tasks towards successful flight of such a configuration is to design a stable and robust control system as it is an underactuated system possessing complex non-linearities and coupled dynamics. Cascaded proportional integral (PI) control approach has provided an efficient solution with stable control performance. A novel motor control loop is implemented to ensure enhanced disturbance rejection, which is also validated through Dryden turbulence model and 1-cosine gust model.Originality/valueRobustness and stability of the proposed control structure for such a dynamically complex UAS configuration is demonstrated with stable attitude and position performance, reference tracking and enhanced disturbance rejection.

Evaluation of Surface Vibrations in the Low and High Frequency Domain

1995 ◽  
Author(s):  
Peter Fischer ◽  
Helmut J. Pradlwarter ◽  
Gerhart I. Schuëller
Keyword(s):  
Frequency Domain ◽  
High Frequency ◽  
Flow Characteristics ◽  
Low Frequency ◽  
Structural Response ◽  
Short Wave ◽  
Fe Model ◽  
Special Cases ◽  
Wide Range ◽  
Surface Vibrations

Abstract The frequency domain of many problems in structural dynamics encompasses a wide range, covering nearly static behavior up to vibration flow characteristics similar to heat transfer. This work presents an uniform approach for low and high frequency vibration analysis, which is based on Finite Element modeling of the structure. Vibrations in the low frequency range are determined by an efficient superposition technique of complex modes, which accounts accurately for any linear damping effect. The modal method is extended to the high frequency domain by applying different levels of averaging to the response and eigenfrequencies and by the introduction of random properties of modeshapes. The high frequency domain is defined by the size of the Finite Elements, i.e. short wave lengths of high frequency modeshapes cannot be represented by the FE-model. The response computation of isolated structures is extended to substructures of complex systems by prescribing stochastic multi-support base excitation at the substructure boundaries. It may be noted, that the presented approach of stochastic high frequency dynamics contains, as special cases, the expressions of the structural response of Statistical Energy Analysis, Bolotin’s integral method and the results of Asymptotic Modal Analysis.

Identification and evaluation for the dynamic signals caused by pressure fluctuation of aerostatic slider

2018 ◽  
Vol 70 (6) ◽  
pp. 927-934 ◽  
Author(s):  
Dongju Chen ◽  
Jihong Han ◽  
Xianxian Cui ◽  
Jinwei Fan
Keyword(s):  
Wavelet Transform ◽  
Correlation Analysis ◽  
Frequency Domain ◽  
Low Frequency ◽  
Measured Signal ◽  
Analysis Method ◽  
Content Type ◽  
Correlation Analysis Method ◽  
The Impact ◽  
Signal Correlation

Purpose To identify the dynamic feature of the aerostatic slider caused by gas film, an evaluation system by a piezoelectric acceleration sensor is presented in time and frequency domain. Design/methodology/approach The dynamic pressure fluctuation is evaluated by the wavelet transform, cross correlation analysis and power spectral density (PSD). Wavelet transform is used to process the measured result of the aerostatic slider and the signal is decomposed into high-frequency and low-frequency signal. Correlation analysis method is used to evaluate the impact of the initial gas gap on the fluctuation in time domain. Findings According to the PSD analysis of the processed signal in the frequency domain, the natural frequency of the aerostatic slider is identified from the measured signal in frequency domain; this method provides a basis for the identification of guideway errors. Research limitations/implications The method can also be applied to the error identification of other components of the machine tool. Originality/value Wavelet transform is used to process the measured result of the aerostatic slider by acceleration sensor, and the signal is decomposed into high-frequency and low-frequency signal. Correlation analysis method is used to evaluate the impact of the initial gas gap on the fluctuation in time domain. According to the PSD analysis of the processed signal in the frequency domain, the natural frequency of the aerostatic slider is identified from the measured signal in frequency domain; this method provides a basis for the identification of slider errors.

The wide range of output frequency regulation method for the inverter using the combination of PWM and DDS

2019 ◽  
Vol 38 (4) ◽  
pp. 1323-1333 ◽  
Author(s):  
Wojciech Pietrowski ◽  
Wojciech Ludowicz ◽  
Rafal Marek Wojciechowski
Keyword(s):  
Single Phase ◽  
Pulse Width Modulation ◽  
Harmonic Distortion ◽  
Low Frequency ◽  
Modulation Method ◽  
Frequency Regulation ◽  
Content Type ◽  
Output Waveform ◽  
Wide Range ◽  
Single Phase Inverter

Purpose The specific modulation methods are used to control different kind of single-phase, as well as three-phase, inverters to ensure flexibility and high quality of the output waveform. This paper aims to present a combination of two classical methods, namely, pulse width modulation method and direct digital synthesis modulation method. Design/methodology/approach The total harmonic distortion of output waveforms of single-phase inverter based on elaborated modulation method has been determined by means of fast Fourier transform analysis. Tests have been carried out by using standard low-frequency application and also a wireless resonant energy link system. Findings Applying appropriate timer parameters of microcontroller enables to obtain a waveform for given output parameters (amplitude, frequency, frequency modulation index, etc.). The only limitation is the computing power of a microcontroller. Originality/value The elaborated method can be successfully used in both low- and high-frequency application ensuring high level of output waveform quality. Additional signal generators and the control of amplitude modulation ratio are no longer indispensable, what simplify immensely a control system.

Towards a transformer transient model as a lumped-distributed parameter system

2017 ◽  
Vol 36 (3) ◽  
pp. 741-750 ◽  
Author(s):  
Sergey E. Zirka ◽  
Yuriy I. Moroz ◽  
Ebrahim Rahimpour
Keyword(s):  
Power Transformer ◽  
Low Frequency ◽  
Fortran Program ◽  
Transient Model ◽  
Content Type ◽  
Voltage Range ◽  
Three Phase ◽  
Wide Range ◽  
Loss Prediction ◽  
Zero Sequence

Purpose The purpose of this study is to develop a topological model of a three-phase, three-limb transformer for low-frequency transients. The processes in the core limbs and yokes are reproduced individually by means of a dynamic hysteresis model (DHM). A method of accounting for the transformer tank with vertical magnetic shunts at the tank walls is proposed and tested on a 120 MVA power transformer. Design/methodology/approach The model proposed has been implemented independently in a dedicated Fortran program and in the graphical pre-processor ATPDraw to the ATP version of the electromagnetic transient program. Findings It was found that the loss prediction in a wide range of terminal voltages can only be achieved using a DHM with variable excess field component. The zero sequence properties of the transformer can be accurately reproduced by a duality-derived model with Cauer circuits representing tank wall sections (belts). Research limitations/implications In its present form, the model proposed is suitable for low-frequency studies. Its usage in the case when transformer capacitances are involved should be studied additionally. Practical/implications The presented model can be used either as an independent tool or serve as a reference for subsequent simplifications. Social/implications The model proposed is aimed at meeting the needs of electrical engineering and ecology-minded customers. Originality/value Till date, there were no experimental data on zero-sequence behavior of three-phase, three-limb transformer with vertical magnetic shunts, so no verified transient model existed. The model proposed is probably the first that matched this behavior and reproduced measured no-load losses for a wide voltage range.

Sensitivity model based PID controller for various high-order processes

2019 ◽  
Vol 38 (6) ◽  
pp. 1855-1873 ◽  
Author(s):  
Sreya Ghosh ◽  
Somnath Pan
Keyword(s):  
Control System ◽  
Pid Controller ◽  
Reference Model ◽  
High Order ◽  
Model Matching ◽  
Content Type ◽  
Set Point ◽  
Model Based ◽  
Load Disturbance ◽  
Matching Technique

Purpose This paper aims to propose a reference model based simple strategy for the design of proportional-integral-derivative (PID) controller using frequency response matching for high-order stable, integrating and unstable processes that may have time-delay and non-minimum phase zero. Design/methodology/approach The reference sensitivity model is designed fulfilling stability conditions of the control system responses such as set-point response, load-disturbance response and noise response along with transient response criteria. The analytical controller thus designed is approximated to a PID controller using a simple formula based on a model-matching technique at low frequency. Findings PID controllers are designed for examples with varied dynamics taken from the literature, and the performances of the designed control systems are compared with some methods prevalent in the literature to show the efficacy of the proposed work. Overall, the method gives satisfactory set-point, as well as load-disturbance responses and controller-outputs in all the cases considered. Originality/value The method is applicable to high-order processes of various monotonic or oscillating dynamics without requiring process reduction. The PID controller designed considering a reference model with suitable criteria ensuring stability and a modified model matching technique, which provides a stable control system for all these high-order processes.

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