# Forthcoming articles

International Journal of Systems, Control and Communications

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International Journal of Systems, Control and Communications (18 papers in press)

Regular Issues

•  Open Access Autonomous Leader-Follower Formation Control of Nonholonomic Wheeled Mobile Robots by Incremental Path Planning and Sliding Mode Augmented Tracking Control. ( Free Full-text Access )
by Kishorekumar Kowdiki, Ranjit Kumar Barai, Samar Bhattacharyya
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 nonholonomic 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 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 nonholonomic constraints, whereas, the sliding mode augmented robust trajectory tracking control component minimizes 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.

• Robust $H_{infty}$ Control for Uncertain 2-D State-Delayed Systems in the Second FM Model
by Khalid Badie, Zakaria CHALH, Mohammed Alfidi
Abstract: This paper investigates the problem of robust $H_{infty}$ control for twodimensional (2-D) discrete state delay systems described Fornasini-Marchesini (FM) second model. The parameter uncertainties are supposed to be normbounded.rnOur attention is focused on designing $H_{infty}$ state feedback controllers guaranteeing the asymptotic stability and $H_{infty}$ performance of the corresponding closed-loop system. A sufficient condition for $H_{infty}$ disturbance attenuation performance for the nominal 2-D discrete state delay system is first obtained. Next, a stabilizing state feedback controller is designed such that the resulting closedloop system is asymptotically stable and achieves a prescribed $H_{infty}$ disturbance attenuation level. Furthermore, the resulting criteria are extended to robust $H_{infty}$ control of the uncertain 2-D state-delay system. Two examples are given to demonstrate the advantages of the proposed methods.
Keywords: 2-D discrete system; robust $H_{infty}$ control; FM second model; LMI.

• Optimal Design of Broadband Matching Networks using Cuckoo Search Optimization 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

• PERFORMANCE ANALYSIS OF VARIOUS SOFT COMPUTING CONTROLLER BASED DYNAMIC VOLTAGE RESTORER
by Kohila Ramkumar, Muthukumar A, Kannan S
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; Power Quality; Synchronous Reference frame theory.

• 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

• A conceptual framework for securing industrial control systems: smart grid environment
by Saqib Ali
Abstract: Cyber-Physical Systems (CPS) utilized 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 organizations such as NIST, ISO, 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 utilizing 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; SCADA; Cybersecurity; Cyber Physical Systems; Smart Grid.

• OPTIMIZATION OF PTS TECHNIQUE FOR PAPR REDCUTION IN MIMO-OFDM BASED CRNs
by Sharanjit Kaur, Inderdeep Kaur Aulakh
Abstract: In cognitive radio networks, the available spectrum has to be shared between various users, OFDM (orthogonal frequency division multiplexing) has a feature that supports multiuser access by assigning subcarriers to different users. In wireless transmissions, OFDM is an emerging expertise as it provides flexibility and high speed data transmission. PAPR is the key challenge in OFDM based cognitive radio system that affects the BER. Many techniques such as clipping & filtering method, partial transmit sequence, tone reservation, selective mapping can be used to reduce the PAPR in OFDM based cognitive radio. In this paper, the main focus is on partial transmit sequence. The existing PTS technique works well in reduction of PAPR. But the major drawback of this technique is that the number of multiplications of IFFT sub-sequences with the phase vectors required in it are very high. Hence the computational complexity of the overall technique increases. To reduce this search and computational complexity, optimization is performed in this paper. Binary particle swarm optimization (BPSO) is used to find the optimized phase vector. This phase vector will be the one having reduced PAPR. Thus the computations are reduced in proposed approach. The purpose of proposed approach is to find out the absolute convergence of MIMO multiplexing to reduce the internal phase to phase PAPR in cognitive radio based networks. The only difference between BPSO and PSO is that in BPSO velocity of the particles are bounded between [0, 1]. The proposed results shows that in case of PTS-BPSO error reduces at higher rate with less PAPR. When the OFDM signal length is 1k then the PAPR is reduced from 11 dB to 5.1 dB. Also in case of Bit error rate for proposed approach the BER is reduced at different SNR values as compared to conventional approach because the PAPR is less due to BPSO optimization.
Keywords: OFDM; PTS; BPSO; PSO; PAPR; BER.

• Design of an automatic voltage regulator based on symmetric root locus technique
by Rittu Angu
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 minimize 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; automatic voltage regulator; symmetric root locus; extended estimator.

• Precoded GFDM System for Self-Interference Mitigation
by Hossein Khaleghi Bizaki, Mohsen Farhang
Abstract: Generalized 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 synchronization requirements. However, the subcarriers 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: GFDM; non-Orthogonal waveform; Precoding technique; Self-Interference.

• 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 crypto system has been proposed. The circuit is made to behave correctly for a long time. By applying pass transistors, the aging effects due to HCI and NBTI are reduced. This fact is helpful to achieve the goal and its performances has 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 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 doesnt change more. The randomness is also shown through NIST tests.
Keywords: Aging; AES; Cryptosystem; Personality ID; TRNG.

• Robust Finite Frequency Hoo Filtering for Uncertain Continuous-Time Systems
by Kaoutar LAHMADI, Abderrahim EL-AMRANI, Bensalem Boukili, Ismail Boumhidi
Abstract: This paper investigates the Hoo filtering problem for uncertain continuous-time systems with finite frequency (FF) specifications. Our goal is to design a new filter guaranteeing an Hoo performance level in specific finite frequency ranges. By virtue of the generalized Kalman-Yakubovich-Popov (gKYP) lemma, Finsler's lemma, polynomially parameter-dependent Lyapunov function and some key matrices to eliminate the product terms between the filter parameters and the Lypunov matrices, we establish some sufficient conditions to characterize this problem in terms of linear matrix inequalities (LMIs). Finally, Illustrative examples are provided to show the usefulness and potential of the proposed results.
Keywords: Finite Frequency Hoo performance Continuous-time Systems Linear Matrix Inequalities (LMIs).

• 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.

• A new PIDF controller structure for delayed process
by Bharat Verma, Prabin Kumar Padhy
Abstract: A new proportional-integral-derivative (PID) control structure (PIDF) for delayed processes is proposed in this paper. It consists of a derivative controller (D) in feedback with a standard proportional-integral (PI) controller. The proposed PIDF controller improves the robustness with respect to time delay and de-noising capability. The proposed controller is similar to a PI controller with a low pass filter in series, which minimises the effect of high-frequency measurement noise. The robustness of the proposed PIDF controller, with respect to the process-delay variation, is verified through simulation of four different processes and results are compared with standard PID controller. The parameters of PID and PIDF controller are tuned by minimising the integral time square error (ITSE) objective function with the help of genetic algorithm.
Keywords: robust control; linear control; dominant pole; PID controller; PIDF controller; delayed process.
DOI: 10.1504/IJSCC.2019.10019518

• Fault-tolerant multi-agent scheme for leader/follower formation control of homogeneous mobile robot team
by Abdelfetah Hentout, Abderraouf Maoudj, Mohamed Ouahal, Abdennour Gasmi
Abstract: This paper deals with fault-tolerance and formation control problems for homogeneous mobile robots under leader/follower failures by using the multi-agent paradigm. These issues are addressed by a cooperative approach supported by two kinds of agents: 1) robot agents (classified into a leader and a set of followers depending on their objective function), assigned to robots for collecting information, making decisions and transferring them to physical robots for execution; 2) supervisory agent (an interface between the control system and the team), synchronises and coordinates tasks of the other agents. These agents interact by a negotiation protocol to satisfy their objectives: 1) preserve predefined leader/follower formation; 2) conserve robots order inside the formation; 3) manage dynamic disturbance events (e.g., unexpected breakdown, integration of new robots). To validate this scheme and evaluate its performances, different simulations are examined by using ten robots evolving inside a grid environment cluttered with static obstacles with/without failures.
Keywords: multi-agent control scheme; leader/follower line formation; fault-tolerance; homogeneous robot team.
DOI: 10.1504/IJSCC.2019.10019520

• Frequency control of an isolated power system considering mutual effects of AGC in presence of energy storage units
by Mallareddy Mounica, Chinta Durga Prasad, Ravi Kumar Jatoth
Abstract: Automatic generation control (AGC) of an isolated power system is investigated in this paper. Performance analysis is carried out by considering the mutual coupling effect between load frequency control (LFC) and automatic voltage regulator (AVR) control loops by adding one fixed and one variable energy storage systems (ESS). The insertion of storage devices reduces the frequency oscillations for various load changes and also reduces the mutual effect of LFC and AVR. Simultaneous coordinated tuning of secondary controller and variable storage unit with particle swarm optimisation (PSO) and improved particle swarm optimisation (IPSO) is carried out to provide control strategy for the system. The system is simulated both in presence and absence of secondary controller in which IPSO gives better performance results than PSO. The simulation is carried out in MATLAB/Simulink software.
Keywords: load frequency control; LFC; automatic voltage regulation; mutual coupling effects; energy storage systems; ESS; power compensation; particle swarm optimisation; PSO; improved PSO; settling time.
DOI: 10.1504/IJSCC.2019.10019517

• Hybrid clipping-PTS using enhanced PSO with Cauchy mutation to reduce PAPR of FBMC 5G systems
by Mohamed Hussein Moharam, Mamdouh Gouda, Hadia M. El Hennawy
Abstract: The first issue of this paper is to make particle swarm optimisation (PSO) on partial transmit sequence (PTS) and clipping methods not simultaneously to get optimal phase factor sets using two sub-block partition and select the optimum level of clipping ratio respectively in order to lessen PAPR. Second issue is to make PSO of hybrid PTS with clipping (PSO-H-CPTS) which is used for the reduction in FBMC/OQAM system. The last issue is describe the joint optimisation between PSO and Cauchy mutation with the hybrid clipping and PTS techniques which is produce best result than other proposed algorithms, the experimental results shows that EPSO-H-CPTS improve the results by 71.5% than conventional traditional PAPR in both clipping and PTS where the PAPR reached to a value 2.9 dB after using joint optimisation hybrid techniques.
Keywords: FBMC/OQAM; orthogonal frequency division multiplexing; OFDM; particle swarm optimisation; PSO; clipping partial transmit sequence; C-PTS; EPSO-H-CPTS; peak to average power ratio; PAPR; complementary cumulative distribution function; CCDF; active constellation extension with tone reservation; TRACE; bit error rate; BER.
DOI: 10.1504/IJSCC.2019.10019523

• A novel self-tuning PI controller for a DFIG-based wind turbine system
by Shubhranshu Mohan Parida, Pravat Kumar Rout, Sanjeeb Kumar Kar
Abstract: This article presents a novel self-tuning proportional integral (ST-PI) controller for a grid connected wind turbine based on doubly-fed induction generator (DFIG) to regulate the active and reactive power under variable wind speed conditions. The gains of the controller are dynamically adjusted according to the error variation during transient conditions to damp the system oscillations faster with better settling time and lesser overshoot. They are designed to vary continuously according to the error based on tanh function logic within a pre-determined range. The proposed self-tuning controller is able to circumvent the problems usually associated during application of conventional PI controller with constant gain such as robustness, adaptability and wide range of operation. Simulation analysis and comparative studies with conventional PI controller reveal the efficacy of the proposed control scheme. Simulation is done for the system model to test the proposed approach using MATLAB.
Keywords: proportional integral controller; PI; self-tuning PI controller; ST-PI; doubly-fed induction generator; DFIG; wind turbine; WT; distributed generator; DG.
DOI: 10.1504/IJSCC.2019.10019522