International Journal of Systems, Control and Communications (8 papers in press)

Regular Issues

• Fixed-time prescribed performance fault-tolerant control for quadrotor UAV based on ESO  
  by Lei Liu, Junfang Li, Yuehui Ji, Junjie Liu, Yu Song, Wenxing Niu 
  Abstract: Considering the need for high precision control in the flight process of quadrotor unmanned aerial vehicle (UAV), a kind of fault-tolerant control strategy based on fixed-time prescribed performance control (FXTPPC) and extended state observer (ESO) is designed to solve the control problem of quadrotor UAV in the case of external disturbance, output error constraint and fault. Firstly, a simplified model of quadrotor UAV is established. Secondly, a double closed-loop fixed-time continuous output feedback controller based on inner loop attitude control and outer loop position control is designed. The actuator fault, sensor fault and external disturbance are estimated and compensated by ESO in real time to effectively solve the quadrotor stability control problem. Further, a FXTPPC function is introduced to convert the original constrained nonlinear system into the equivalent unconstrained nonlinear system. Finally, the stability analysis shows that the designed controller can guarantee the stability of system. Simulation results also verify the effectiveness of the proposed scheme. The tracking error can converge rapidly to the range specified by the performance function within the fixed-time.
  Keywords: quadrotor UAV; actuator fault; sensor fault; output error constraint; fixed-time continuous output feedback controller; FXTPPC; extended state observer; ESO.
  DOI: 10.1504/IJSCC.2022.10052557
   
  
• A wideband G-shaped array antenna for X and Ku band applications  
  by Ponugoti Vamshi, Mysa Hari Haran Kumar, Vaishnavi Govind, V. Harini, Aylapogu Pramod Kumar 
  Abstract: A wideband microstrip G-shaped antenna array is described in this study that performs in X and Ku band applications. The wideband operation, transmitted power, bandwidth, gain, and polarisation type all have a role in the choice of radiating element form. The reflection coefficient values are observed as -10.6 dB, -10.5 dB, -12.09 dB, -11.14 dB, -13.8 dB, -14.2 dB and -20.46 dB at resonating frequencies like 8.21 GHz, 10.45 GHz, 11.7 GHz, 12.2 GHz, 12.47 GHz, 14 GHz, and 15 GHz with again values of 2.42 dBi, 2.86 dBi, 4.24 dBi, 3.32 dBi, 4.09 dBi, 6.25 dBi and 6.34 dBi. The suggested antenna prototype is constructed and simulated for a frequency range of 10 GHz to 16 GHz, with a fractional bandwidth of 46.15%. According to the simulation findings, the suggested wideband array antenna design is theoretically viable.
  Keywords: antenna array; wideband; microstrip; multiband; polarisation.
  DOI: 10.1504/IJSCC.2023.10053673
   
  
• New result about parameters identification of delayed chaotic systems: a target system-based method  
  by Qianwen Xue, Fei Wang, Xin Sui 
  Abstract: In this paper, the parameter identification problem of a class of time-delay chaotic systems is studied based on the method of target systems. First of all, this paper gives a time-delay chaotic system model with unknown parameters, a target system and adaptive feedback controllers. Then, the corresponding updated laws of the adaptive parameters and control gains are designed, and it is strictly proved that the adaptive parameters will converge to the real values of unknown parameters through Lyapunov stability theory and Babarat's lemma. Finally, we give several numerical simulation examples to verify the effectiveness of the theoretical results. We show that the unknown parameters of some systems cannot be identified by the classical adaptive synchronisation method, but the method proposed in this paper can still work.
  Keywords: parameters identification; adaptive synchronisation; delayed chaotic systems.
  DOI: 10.1504/IJSCC.2022.10049473
   
  
• Performance analysis of channel estimation techniques for 5G massive MIMO-OFDM system  
  by T. Aravinda Babu, K. Deergha Rao 
  Abstract: Massive MIMO systems are now being developed for the 5G requirement, combining the OFDM technology to provide very high data rates in a frequency selective fading channel. The data rate and latency play an essential part in the construction of 5G standards. The channel estimation (CE) is critical in a massive MIMO OFDM system. However, the latency may be more traditional channel estimators like least squares (LS) and minimum mean square error (MMSE) estimators because it involves matrix inversion. The proposed system uses the QR decomposition orthogonal matching pursuit (QRDOMP) channel estimation method, which does not involve matrix inverse. After channel estimation, different linear equalisation techniques such as MMSE and AMP are used to detect the signal. In this paper, the BER and latency performance of the proposed system with various channel estimation techniques (LS, MMSE, and QRDOMP) using AMP equalisation is analysed in comparison to that of the MMSE equalisation.
  Keywords: massive MIMO; OFDM; channel estimation; channel equalisation; QRDOMP; approximate message passing; AMP; QAM.
  DOI: 10.1504/IJSCC.2022.10050384
   
  
• Evaluation criteria for network security solutions based on behaviour analytics  
  by Manya Ali Salitin, Ali Hussein Zolait 
  Abstract: This research aims to develop a set of evaluation criteria to identify and select a reliable user entity behaviour analytics (UEBA) solution for enterprises. A quantitative method is used to validate a set of evaluation criteria. Data were obtained from 280 high-profile network security professionals and analysed. Researchers used confirmatory factor analysis to validate the measurement model for convergent validity and reliability of criteria constructs, including evaluating the priority of each criterion item by security professionals. Findings depict that UEBA criteria are a multidimensional construct comprising six factors: 1) general capabilities; 2) use cases; 3) log reports for analysis of user behaviour; 4) profiling models; 5) alert reports; 6) integration with other solutions. Although the study's limitation might come from the respondents if selected globally, the results might be somewhat different. The novelty of this research work lies in developing and validating an instrument, empirically tested and validated by network security professionals and used by them to choose a reliable solution for their companies and what features of network security solutions are must as per the perception of high profile users.
  Keywords: user entity behaviour analytics; UEBA; security solution; security measurement model; network security; security solutions criteria.
  DOI: 10.1504/IJSCC.2022.10050498
   
  
• Fast-convergent model predictive control of omni-directional mobile robots  
  by Yin Hu, Minghui Zhao, Xuebo Zhang 
  Abstract: Omni-directional wheeled mobile robots (OWMRs) present high manoeuvrability and can move in all directions of the plane. However, for active-caster-type OWMRs (ACT-OWMRs), satisfying physical constraints of multiple motors is challenging. To guarantee motor constraints and improve the tracking control performance, a new model predictive control (MPC)-based controller termed as 'MPC-FCR' is designed, which embeds a real-time fast-convergent trajectory planner to generate high efficient gentle reference trajectory. Such a framework has two main advantages. First, the gentle trajectory generation module is formulated as a constrained optimisation problem, which can achieve fast convergence performance while satisfying the robot constraints. Second, both motor and robot constraints are considered in MPC-FCR control law. The proposed MPC-FCR is implemented to achieve real-time performance within a control period of 20 milliseconds. Experimental results show the superior performance of MPC-FCR in terms of convergence speed and the capability to handle physical constraints, compared with the classical controller.
  Keywords: trajectory tracking control; model predictive control; fast-convergent gentle trajectory planning; omni-directional wheeled mobile robot.
  DOI: 10.1504/IJSCC.2022.10051433
   
  
• A compact low profile wideband circularly polarised antenna for WLAN applications  
  by Aylapogu Pramod Kumar 
  Abstract: In the past decade, the rapid improvement in wireless communication system has motivated extended research on low profile, compact and cost effective circularly polarised wideband patch antenna. A flexible and new design of wideband circularly polarised antenna finds application of WLAN. The proposed CP wide band antenna contains a rectangular radiating patch with slots on the opposite sides of the patch to achieve CP and the o-shaped semi-circle with squares inscribed to get wide band with truncated ground to achieve two resonating frequencies on little cost FR4-substrate bear thickness of 1.6 mm. The proposed final design of the antenna is resonating at frequencies 4 GHz and 5 GHz respectively with good impedance matching values of -37.44 dB and -49.72 dB. The propose structure is maintaining its VSWR at the respective bands from 1-2 with antenna gain around 2.5 dBi. The main objective of this article is to achieve the wide bandwidth and circular polarisation with minimal interferences.
  Keywords: WLAN; gain; bandwidth; S₁₁; VSWR.
  DOI: 10.1504/IJSCC.2022.10051617
   
  
• Study of decoupling between closely spaced microstrip MIMO antennas using microstrip resonator  
  by Swati Bhattacharjee, Chandan Kumar Ghosh 
  Abstract: This paper presents a novel decoupling technique between two closely spaced MIMO antennas whose edge-to-edge spacing is 0.03 λ (1.975 mm) where λ is the wavelength in the dielectric medium. The closely spaced MIMO antennas have a major disadvantage of high mutual coupling (MC) which affects its entire characteristics; thereby degrading the antenna performance. To overcome this problem, a microstrip resonator structure is introduced in between the antennas that act as a decoupled device. The microstrip resonator acts as an electrical wall between the MIMO antennas. The antenna parameters are simulated using IE3D EM simulator and a suppression of 48 dB MC is achieved at the resonant frequency of 4.85 GHz. The MIMO antennas have been fabricated and the results are compared with the simulated ones. The antenna finds its suitability in applications in fields of wireless communication, WLAN and satellite communication systems.
  Keywords: microstrip antenna; MIMO; mutual coupling; MC; microstrip resonator; wireless communication.
  DOI: 10.1504/IJSCC.2022.10051961