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### International Journal of Systems, Control and Communications

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International Journal of Systems, Control and Communications (19 papers in press)

Regular Issues

•  Open Access Autonomous leader-follower formation control of non-holonomic wheeled mobile robots by incremental path planning and sliding mode augmented tracking control ( Free Full-text Access )
by Kishorekumar H. Kowdiki, Ranjit Kumar Barai, Samar Bhattacharya
Abstract: This paper presents a novel robust and autonomous formation control scheme for wheeled mobile robots in the leader-follower formation control framework considering their non-holonomic constraints. In the proposed formation control scheme, the leader robot of the group plans its path of navigation autonomously in a cluttered environment by employing incremental path planning by modified artificial potential field. Then, the follower robots in the group plan their path in order to follow the leader robot by maintaining a particular formation using the separation-bearing (l − Ψ) control. Then the formation control problem has been transformed into a trajectory tracking control problem. The kinematic control component of the tracking controller provides the necessary velocity input for eliminating the non-holonomic constraints, whereas, the sliding mode augmented robust trajectory tracking control component minimises the effects of nonlinearities, model uncertainties, parameter variations, and disturbances. The effectiveness of the proposed control law has been established by simulation studies.
Keywords: artificial potential field; autonomous navigation; formation control; leader-follower; trajectory tracking; kinematic control; sliding mode control.

• Improved finite frequency Hoo filtering for Takagi-Sugeno fuzzy systems
by Abderrahim EL-AMRANI
Abstract: This paper investigates the design problem of Hoo filtering for discrete non-linear systems in the Takagi-Sugeno (T-S) form. Our aim is to design a new filter guaranteeing an Hoo performance level in specific finite frequency (FF) ranges. Using the well-known generalised Kalman Yakubovich Popov lemma, Finslers lemma, sufficient conditions for the existence of Hoo filters for different FF ranges are proposed and then unified in terms of solving a set of linear matrix inequalities (LMIs). Two examples are given to illustrate the effectiveness and the less conservatism of the proposed approach in comparison with the existing methods.
Keywords: Finite Frequency; Hoo Filtering; Takagi-Sugeno (T-S) Fuzzy Systems; Linear Matrix Inequalities (LMIs).

by Wesam Jasim, Dongbing Gu
Abstract: In this work, a leader-follower formation control problem of quadrotors is investigated. The quadrotor dynamic model is represented by unit quaternion with the consideration of external disturbance. Nonlinear $H_{\infty}$ design approach is introduced and robust controllers for both leader and follower robots are derived by solving a Hamilton-Jacobi inequality following from a result for general nonlinear affine systems. Then some robustness conditions of the proposed controllers are obtained by selecting appropriate parametrised Lyapunov functions. The resultant state feedback controllers establish the asymptotically stability of the closed-loop nonlinear system. In addition, integral backstepping (IB) controllers are also derived for the leader-follower formation control problem. The purpose of designing IB controllers is to evaluate the robustness of $H_{\infty}$ controllers by comparison. The simulation results from both types of controllers are compared and robustness performance of the $H_{\infty}$ controllers over the IB controllers are demonstrated.

• Analytic Hierarchy Process Based Model Reduction of Higher Order Continuous Systems Using Sine Cosine Algorithm
by Tapan Prakash, S.P. Singh, V.P. Singh
Abstract: The analysis of higher order systems is tedious and cumbersome task. This motivated analysts to reduce higher order systems into lower order models using mathematical approaches. In this paper, an analytic hierarchy process (AHP) based approximation of stable higher order systems to stable lower order models using sine cosine algorithm (SCA) is presented. The stable approximant is deduced by minimizing the relative errors in between time moments and Markov parameters of the system and its approximant. In order to match the steady states of the system and its approximant, the first time moment of the system is retained in the approximant. AHP is utilized to convert multi-objective problem of minimization of errors in between time moments and Markov parameters into a single objective problem by proper assignment of weights. To ensure the stability of the approximant, Hurwitz criterion is utilized. The systematic nature and efficacy of the proposed technique is validated by deriving approximants for three different test systems.
Keywords: Analytic hierarchy process; model reduction; Padé approximation; Routh approximation; sine cosine algorithm.

• Low power Experimental Prototype of a controlled Three- Phase Inverter using D.S.P (TMS320F2812) for a Hydraulic Energy Conversion Chain Application
by Chirine BENZAZAH, Loubna LAZRAK, Soukaina EL DAOUDI, Mustapha AIT LAFKIH
Abstract: This paper deals with a part implementation of the distributed generation chain system based on hydraulic power source operated in low power and controlled by DSP F2812. The experimental part of the chain includes a controlled two-level three phase inverter connected, via an LC filter, to a load. This latter consists of a balanced three phase resistive without neutral point joint, for this reason, the implementation requires fewer sensors as measuring devices. The proposed control strategy uses just two regulation loops; one of them is for the AC output voltages and the other one is for the input inductor currents of LC filter. This strategy was developed on Matlab-Simulink and implemented in eZdsp TMS320F2812 DSP board from Spectrum Digital. To confirm the efficiency and robustness of the chain part implementation, the experimental results using the implemented inverter was compared with a compact industrial module 7MBR15SA120 inverter mounting with the same control interface and measurement cards. The experimental waveforms comparison prove that there is a good match between the two practice prototypes, validate the theoretical study as well as the simulation results obtained and confirm the effectiveness of the proposed control strategy.
Keywords: (three phase inverter; DSP F2812 controller; CCS; MATLAB interface; Digital model; Power Integrated Module 7MBR15SA120; IRGPS60B120KDP).

• Performance Superiority of CA_TM Model Over N-P Algorithm in Detecting 2 Fluctuating Targets with Four Degrees of Freedom
Abstract: The receiving of targets information mixed with undesired contribution of clutter causes affects the operation of radar systems. Modern radars have adopted adaptive processing techniques to mitigate the deleterious effects of the unwanted clutter and jammer. In this regard, the CFAR processors play a vital role in organizing the detection of fluctuating targets in heterogeneous background environments. Specifically, the popular CA-CFAR processor is incapable of maintaining its design false alarm probability when facing clutter with statistical variations. OS and TM algorithms have been suggested to achieve robust estimates of the threshold in heterogeneous situations. These techniques, however, do not fully utilize the a priori information related to the clutter distribution resulting in degradation in their detection performance in homogeneous clutter. In order to simultaneously exploit the merits of CA, and OS or TM processors, a hybrid combination of them have been recently proposed. They are named as CA_OS and CA_TM approaches. This paper is devoted to the analysis of these new models in the case where the radar receiver post-detection integrates M-pulses to carry out its object. Closed-form expression is derived for their detection performance. The primary as well as the outlying targets are assumed to be fluctuating following χ2-distribution with four-degrees of freedom in their fluctuation. Our simulation results reveal that the new version CA_TM exhibits a homogeneous performance that outweighs that of the classical Neyman-Pearson (N-P) detector which is employed as a baseline comparison for other techniques in the CFAR world.
Keywords: adaptive processors; clutter and interference; derived detectors; χ2-distribution; Swerling models; SWIII & SWIV; postdetection integration of M pulses; multitarget environments.

• Robust Output Feedback Control for Uncertain Chaotic Systems
Abstract: Chaos phenomena can be found in many scientific disciplines such as astronomy, biology, chemistry, engineering, geology, mathematics, medicine, meteorology, and even social sciences. Such phenomena can seriously affect the behavior of some vital applications such as communications and security systems. Hence, a controller is required to handle chaotic behaviors that affect systems stability. In this paper, a robust output feedback controller is proposed to stabilize electronic circuits used in communications and security systems that exhibit chaotic behaviors. The proposed controller is designed to deal with unknown system parameters and time-varying uncertainties. Only the system output is utilized in the proposed controller and other states are estimated. Therefore, a high gain observer is utilized. Numerical study is introduced in this paper to demonstrate the robustness and effectiveness of the proposed controller. The controller performance is investigated under various system configurations and different operating conditions and a satisfactory tracking is observed.
Keywords: chaotic system; control of sprott circuit; robust control; output feedback control; high gain observer.

• Adaptive Neural network control for a class of MIMO Non-affine uncertain systems with input dead-zone nonlinearity and external disturbance
by Zerari Nassira, Mohamed Chemachema, Najib Essounbouli
Abstract: This paper studies an adaptive tracking control for a class of multi-input multi-output (MIMO) non-affine nonlinear systems, with input Dead Zone nonlinearity and external disturbances. By using the mean-value theorem, the system model is transformed into an affine form so as the difficulty in controlling non-affine systems is overcome. In the proposed control design, neural networks (NNs) are used to approximate the unknown nonlinearities based on their universal approximation properties. To compensate for approximation errors and external disturbances, an adaptive robust control term is introduced. In comparison with existing approaches, the structure of the designed controller is considerably simpler, and can handle a wider range of nonlinear systems. The stability of the closed-loop system is investigated by using Lyapunov theory. The simulation results illustrate the proposed method.
Keywords: Adaptive control system; Neural networks; Multi-input Multi-output (MIMO) unknown non-affine Systems; Dead Zone input.

• Scalable Energy Efficient Routing Mechanism Prolonging Network Lifetime in Wireless Sensor Networks
by Omkar Singh, Vinay Rishiwal
Abstract: Due to the tiny size, nodes in a Wireless Sensor Network (WSN) are restricted in battery capacity. As a result, a node and in turn a network of such nodes is not operational for a long time. Further, in some hostile area battery cannot be replaced easily once deployed. Therefore, an energy conservation scheme or algorithm is needed to prolong the network lifetime. In this paper, an Energy Efficient Routing Scheme (EERS) is proposed and evaluated. This scheme extends the lifetime of network by selecting the finest shortest path to transmit data packets to the destined nodes. EERS selects a path/quality link over which it has minimum number of hops with maximum remaining energy over that path. Proposed scheme EERS is compared with other existing schemes for different parameters and varying size of network (100-1000 nodes). The Simulation results shows that the EERS scheme prolongs the network lifetime 10%-15% as compared to other considered schemes. EERS also minimizes the delay for transmitting data packets and increases the packet delivery ratio.
Keywords: WSN; Routing; Energy; DEEC; EESAA; EAP; EERS.

• Robust H control for uncertain 2D state-delayed systems in the second FM model
by Khalid Badie, Mohammed Alfidi, Zakaria Chalh
Abstract: This paper investigates the problem of robust H control for two-dimensional (2D) discrete state delay systems described by the Fornasini-Marchesini (FM) second model. The parameter uncertainties are supposed to be norm-bounded. Our attention is focused on designing H state feedback controllers guaranteeing the asymptotic stability and H performance of the corresponding closed-loop system. A sufficient condition for H disturbance attenuation performance for the nominal 2D discrete state delay system is first obtained. Next, a stabilising state feedback controller is designed such that the resulting closed-loop system is asymptotically stable and achieves a prescribed H disturbance attenuation level. Furthermore, the resulting criteria are extended to robust H control of the uncertain 2D state-delay system. Two examples are given to demonstrate the advantages of the proposed methods.
Keywords: 2D discrete system; robust H control; FM second model; linear matrix inequality; LMI.
DOI: 10.1504/IJSCC.2019.10020332

• Optimal design of broadband matching networks using cuckoo search optimisation algorithm
Abstract: In this work, a novel evolutionary optimisation algorithm is introduced for the design of broadband matching networks connecting a resistive source generator and a complex inductive load. Impedance matching networks are the key for full transfer of power to the load. They should offer matching over the entire frequency concerned band. A low noise amplifier (LNA) is also optimised to attain the target gain and noise figure specifications over a definite bandwidth, throughout lumped LC elements. Cuckoo search optimisation algorithm (CSOA) is inspired by the life of a bird family, called cuckoo, offers excellent results with simple tuning parameters compared to previous conventional and meta-heuristic optimisation algorithms. It is extremely powerful in solving engineering optimisation problems. Simulation results for broadband impedance matching networks are presented and analysed and the optimised matching network improves well the performances of the circuit.
Keywords: broadband; matching network; low noise amplifier; LNA; antenna; cuckoo search algorithm.
DOI: 10.1504/IJSCC.2019.10018571

• FBMC vs. OFDM: 5G mobile communication system
by Arun Kumar, Shikha Bharti, Manisha Gupta
Abstract: The study presents the designing of an orthogonal frequency division multiplexing (OFDM) and filter bank multi carrier (FBMC) modulation techniques. The proposed method consists of OFDM and FBMC prototype filters for transmitting and receiving the data symbols. Both of them are multicarrier technologies used to increase the performance of wireless communication system. Transmission waveform, bit error rate (BER), peak average power ratio (PAPR), capacity and spectrum sensing measurements were simulated and analysed.
Keywords: filter band multi carrier; FBMC; orthogonal frequency division multiplexing; OFDM; peak average power ratio; PAPR; capacity; bit error rate; BER.
DOI: 10.1504/IJSCC.2019.10019229

• Performance analysis of various soft computing controller-based dynamic voltage restorer
by J. Kohila, A. Muthu Kumar, S. Kannan
Abstract: The implementation of custom power devices (CUPD) such as dynamic voltage restorer (DVR), distribution static compensator (DSTATCOM) and unified power quality conditioner (UPQC) has become essential for reducing the impact of PQ problems. More specifically, DVR plays vital role for proving solution to the voltage sag problems and to restore the load voltage with in few milliseconds. The performance of the DVR depends on the control strategy adopted with the algorithm. Synchronous reference frame theory (SRFT)-based ANFIS controller is proposed in this paper. The performance of the proposed control strategy is simulated for various conditions like line to ground, double line to ground and three phase fault in MATLAB/Simulink. From the simulation study, it is found that the ANFIS-based DVR helps to mitigate the voltage sag and reduces the harmonics. The proposed ANFIS-based DVR compared with PI, fuzzy and ANN-based controllers.
Keywords: dynamic voltage restorer; DVR; synchronous reference frame theory; SRFT; power quality.
DOI: 10.1504/IJSCC.2019.10020334

• A conceptual framework for securing industrial control systems: smart grid environment
by Saqib Ali, Mohammed Al Abri
Abstract: Cyber physical systems (CPSs) utilised in many of the critical infrastructures including the smart grid. The operational activities of smart grid's CPS use different industrial solution such as industrial control systems (ICS) for monitoring and controlling the physical architecture of smart grid. Therefore, it is quite essential to keep these industrial control systems secure and safe from potential hazards and cyber world as it may be harmful for human safety, strategic infrastructure of a country and also for the economy. The study gathered the scattered guidelines, best practices and policies available from various organisations such as National Institute of Standards and Technology (NIST), ISO, and North American Electric Reliability Corporation (NERC) for the purpose of developing safe and secure ICS security systems and also the knowledge about the issues involved in ICS security and protection. A conceptual framework is proposed and developed to address the shortcomings in-order to protect the ICS systems in a smart grid environment. The proposed framework was developed by reviewing related studies, standards and utilising IT security working experience. This framework will not only expand the horizon of knowledge but also provides pathway for the development of existing activities of CPS applications such as smart grid.
Keywords: industrial control systems; ICS; supervisory control and data acquisition; SCADA; cybersecurity; cyber physical systems; CPSs; smart grid.
DOI: 10.1504/IJSCC.2019.10021994

• Optimisation of PTS technique for PAPR reduction in MIMO-OFDM-based CRNS
by Sharanjit Kaur, Inderdeep Kaur Aulakh
Abstract: In CRNs, the available spectrum has to be shared between various users, OFDM has a feature that supports multiuser access by assigning subcarriers to different users. In wireless transmissions, PAPR is the key challenge in OFDM that affects the BER. In this paper, the main focus is on PTS. The drawback of existing PTS technique is that the number of multiplications of IFFT sub-sequences with the phase vectors required in it are very high. To reduce computational complexity, optimisation is performed. BPSO is used to find optimised phase vector. This phase vector will be one having reduced PAPR. The purpose is to find out the absolute convergence of MIMO multiplexing to reduce the internal phase to phase PAPR in cognitive radio based networks. Results show that in case of PTS-BPSO error reduces at higher rate with less PAPR. BER is reduced at different SNR values as compared to conventional approach.
Keywords: orthogonal frequency division multiplexing; OFDM; partial transmit sequence; PTS; binary particle swarm optimisation; BPSO; particle swarm optimisation; PSO; peak-to-average power ratio; PAPR; bit error rate; BER.
DOI: 10.1504/IJSCC.2019.10021995

• Design of an automatic voltage regulator based on symmetric root locus technique
by Rittu Angu, R.K. Mehta
Abstract: An automatic voltage regulator (AVR) design based on symmetric root locus (SRL) technique for a synchronous machine infinite bus (SMIB) power system is presented. The SRL technique is used to minimise the amplifier saturation by placing the closed-loop poles (CLPs) of the system at desired locations. The desired CLPs are decided by considering the dominant pole locations that provide maximum damping on the SRL plot. The design incorporates an extended estimator to deal with uncertainties introduced due to variations of parameters or operating conditions. They reconstruct the state information including the state of disturbance dynamics simultaneous to implement full state feedback and using the reconstructed disturbance estimate to compensate the effect of external disturbance or parameter uncertainties. The performance of the system is analysed through simulating at different operating conditions. The control method improves the tracking response and provides zero estimation error in the steady-state. Illustrative examples have been provided to demonstrate the effectiveness of the developed methodology.
Keywords: synchronous machine infinite bus; SMIB; automatic voltage regulator; AVR; symmetric root locus; SRL; extended estimator.
DOI: 10.1504/IJSCC.2019.10022001

• Precoded GFDM system for self-interference mitigation
by Mohsen Farhang, Hossein Khaleghi Bizaki
Abstract: Generalised frequency division multiplexing (GFDM) is a multicarrier transmission scheme that offers a flexible framework to address diverse requirements of fifth generation of cellular networks. Compared to orthogonal frequency division multiplexing (OFDM), the application of pulse shaping in GFDM can control the out of band (OOB) radiation and enables relaxed synchronisation requirements. However, the sub-carriers in GFDM are no longer orthogonal and there is inherent interference. Since this interference is known at the transmitter, it can be mitigated by means of precoding techniques. In this paper, Tomlinson-Harashima precoding (THP) scheme is applied to GFDM transceiver and its performances is compared to previous methods in terms of bit error rate (BER) and peak to average power ratio (PAPR). The results show that the proposed precoder outperforms previous methods in both BER and PAPR.
Keywords: generalised frequency division multiplexing; GFDM; precoding technique; non-orthogonal waveform; self-interference.
DOI: 10.1504/IJSCC.2019.10022002

• Anti aging controllable true random number generator for secured AES-based crypto system
by Muthukumar Arunachalam, Sivasankari Narasimhan, Rampriya Kaniram
Abstract: A tetrahedral oscillator-based true random number generator for secret key generation in cryptosystem has been proposed. The circuit is made to behave correctly for a long time. By applying pass transistors, the aging effects due to hot carrier injection (HCI) and negative bias temperature instability (NBTI) are reduced. This fact is helpful to achieve the goal and its performances have also been improved. Pass transistor makes the transistors to operate only at enabling times. Thus, bit flipping in normal designs are reduced. Due to the complexity in the tetrahedral oscillator hacking will be very tough. The secret key generated from TRNG circuit is adopted in advanced encryption standard (AES) cryptosystem to maintain an off-chip database. Moreover, controlling circuits for TRNG have been introduced because in any of the cryptosystem man-in-middle attack is possible. To avoid this controlling circuits are used to identify the authenticity of customers. Simulation results explain that our aging resistant design can be used for generating more reliable keys. Although the operating conditions changes, the DC operating point of the system does not change more. The randomness is also shown through NIST tests.
Keywords: aging; advanced encryption standard; AES; cryptosystem; personality ID; TRNG; hash function; tetra hedral oscillator; sampling; pass transistors; operating point.
DOI: 10.1504/IJSCC.2019.10022004

• Robust finite frequency H filtering for uncertain continuous-time systems
by Kaoutar Lahmadi, Abderrahim El-Amrani, Bensalem Boukili, Ismail Boumhidi
Abstract: In this paper, the H filtering problem for a class of continuous-time polytopic uncertain systems is studied. Different from the traditional methods dealing with polytopic uncertainties in the full frequency domain, not only its values but also the finite frequency (FF) cases are considered. Our goal is to design a the filters guaranteeing an H performance level in the finite frequency (FF) domains. By using the generalised Kalman-Yakubovich-Popov (gKYP) lemma, polynomially parameter-dependent Lyapunov function and some key matrices, we establish new sufficient conditions to characterise this problem in terms of linear matrix inequalities (LMIs). Finally, a two examples are used to show the superiority and effectiveness of the proposed methods.
Keywords: finite frequency; H performance; continuous-time systems; linear matrix inequalities; LMIs.
DOI: 10.1504/IJSCC.2019.10022005