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Gait design for walking biped robots, that can preserve stability against a known range of disturbances, is very important in real applications. Designing an exponentially stable walking gait with desired features for biped robots has been recently done by an online reinforcement learning method. However, the designed gait might not be robust enough against disturbances. In this paper, we extend a robust version of the method against modeling errors/disturbances. It is done by minimizing the costs of worst rollouts which are generated in the presence of different modeling errors/disturbances. The proposed method's ability to adapt the controller is studied for some robust applications. The simulation shows that the resulted gaits are exponentially stable and robust against modeling errors/disturbances in a feasible range. [ABSTRACT FROM AUTHOR]

In this paper, the robust sampled-data input H∞ control of uncertain continuous switched time-delay systems with linear fractional perturbations and aperiodic sampling is considered. Some delay-dependent LMI optimisation results are proposed to achieve the design of robust controller for switched system with switching signal selection and arbitrary switching. Practical implementation of the proposed synchronous switching of switching signal and sampled-data input is easy and available. Finally, some numerical examples are illustrated to show the main results. [ABSTRACT FROM AUTHOR]

With the development of technology, people work hard on image processing and artificial intelligence which require a lot of computer resources. Instead of simply speeding up calculations with processors, people develop the technology of the Cloud with the Internet which performs high‐quality calculations and has quite a huge amount of storage. Thus, in this paper, the authors use a kind of encryption methods, Secure Multi‐Party Computation (SMPC), to protect the important information which is based on the absence of a trusted party and does not use specific keys or methods to maintain the confidentiality of data. Furthermore, the authors also use the error correction, Berlekamp–Welch (BW) algorithm, to double‐check the correction of the information. To apply the two algorithms to image enhancement and convolution neural networks (CNN), the authors will also discuss the homomorphism in all operations, including addition, multiplication, division etc., and find the best way to encrypt and decrypt the information. Finally, the authors will implement the system with cloud computing to decrease the consumption of computer resources and build a system that can do image enhancement and CNN. [ABSTRACT FROM AUTHOR]

This paper investigates the robust synchronisation problem for a class of Rössler systems with multiple time delays. Based on the proportional-integral switching surface, a sliding mode control (SMC) is derived to not only guarantee synchronisation between the master and slave Rössler systems with multiple time delays but also have aH∞noise perturbation attenuation performance. The parameter matrix necessary for constructing both PI switching surface and the SMC can be easily solved by linear matrix inequality optimisation technique. The simulations results are presented to show the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, synchronization of Sprott chaotic systems and its application in secure communication are presented. We first utilize a proportional-integral-derivative (PID) control scheme to solve the synchronization problem of chaotic systems. Then for the purpose of application to secure communication, a state signal of the analog chaotic system is converted to a digital train with variable pulse width (square wave with random frequency) by voltage controlled oscillator (VCO). The original digital message is masked by the digital train generated from VCO in the chaotic transmitter via a logical exclusive-OR (XOR) operation and it can be successfully recovered by another VCO and XOR operation at the chaotic receiver due to the synchronization. To verify the system performance, basic electronic components containing operational amplifiers (OPAs), resistors and capacitors are used to implement the proposed PID-based chaotic secure communication system. Finally, the experimental results validate the proposed chaotic communication approach. [Copyright &y& Elsevier]

Abstract: This study is concerned with a deterministic response time design for computer-based systems in the nuclear industry. In current approach, Petri nets are used to model the requirement of a system specified with sequence diagrams. Also, the linear logic is proposed to characterize the state of changes in the Petri net model accurately by using symbolic time representation for the purpose of acquiring deterministic behavior. An illustrative example of the bistable processor logic is provided to demonstrate the practicability of the proposed approach. [Copyright &y& Elsevier]

This paper investigates the guaranteed cost control of chaos problem in 4D Lorenz-Stenflo (LS) system via Takagi-Sugeno (T-S) fuzzy method approach. Based on Lyapunov stability theory and linear matrix inequality (LMI) technique, a state feedback controller is proposed to stabilize the 4D Lorenz-Stenflo chaotic system. An illustrative example is provided to verify the validity of the results developed in this paper. [ABSTRACT FROM AUTHOR]

This paper investigates the guaranteed cost control of chaos problem in permanent magnet synchronousmotor (PMSM) via Takagi-Sugeno (T-S) fuzzy method approach. Based on Lyapunov stability theory and linear matrix inequality (LMI) technique, a state feedback controller is proposed to stabilize the PMSM systems. An illustrative example is provided to verify the validity of the results developed in this paper. [ABSTRACT FROM AUTHOR]

This paper investigates the guaranteed cost control problem of uncertain non-linear systems with time-varying delays via the Takagi-Sugeno fuzzy model approach. Based on the Lyapunov-Krasovskii functional theory and the linear matrix inequality technique, a state feedback controller is proposed to stabilise the non-linear systems and minimise the guaranteed cost of the closed-loop systems. Both delay-dependent and delay-independent stability criteria are derived to guarantee the asymptotic stability of closed-loop systems. Furthermore, the supplementary requirement that the time-derivative of time-varying delays must be smaller than one is released for the proposed delay-dependent stability criterion. Two illustrative examples are provided to verify the validity of the results developed in this paper. [ABSTRACT FROM AUTHOR]

Abstract: This paper investigates the global asymptotic stability (GAS) for a class of nonlinear neural networks with multiple delays. Based on Lyapunov stability theory and the linear matrix inequality (LMI) technique, a less conservative delay-dependent stability criterion is derived. The present result is shown to be less conservative than those given in the literature. [Copyright &y& Elsevier]

Abstract: This article investigates the H ∞ synchronization problem for a general class of chaotic systems. Based on Lyapunov theory, linear matrix inequality (LMI) and linear matrix equality (LME) formulation, the output feedback controller is established to not only guarantee stable synchronization of both master and slave systems but also reduce the effect of external disturbance to an H ∞-norm constraint. Two illustrative examples are provided to demonstrate the effectiveness of the developed theoretical results. [Copyright &y& Elsevier]

This paper investigates the switching on switching rule and sampling input to guarantee (Q,S,R)- γ -dissipative and H 2 performances for switched systems with mixed time delays. Synchronous switching can be used to overcome the difficulty in implementation of real-time switching for signals and sampling. The design of sampling input under arbitrary switching for a switched system is also considered in this paper. A new proposal for a full matrix formulation approach and inequality are applied to achieve the main results. Finally, some numerical examples are illustrated to show the efficiency of the main contribution. [ABSTRACT FROM AUTHOR]

In this paper, we propose synchronous switching of rule and input to achieve H∞ performance for an uncertain switched delay system with linear fractional perturbations. Our developed simple scheme utilizes the linear matrix inequality optimization problem to provide a feasible solution for the proposed results; if the optimization problem was feasible, our proposed robust H∞ control could be designed. The feasibility of the optimization problem could be solved using the LMI toolbox of Matlab. In this paper, robust control with sampling is proposed to stabilize uncertain switching with interval time-varying delay and achieve H∞ performance. Interval time-varying delay and sampling were considered instead of constant delay and pointwise sampling. A full-matrix formulation approach is presented to improve the conservativeness of our proposed results. Some numerical examples are demonstrated to show our main contributions. [ABSTRACT FROM AUTHOR]

The purpose of this research is to develop a high-efficiency, low-cost, and easy-to-use tracking system for vehicles, and it is expected that the system can be extended to areas such as service robots, autonomous driving, and manufacturing. In this paper, we introduced an object detection algorithm based on convolutional neural networks to realize face recognition, which has better efficiency and robustness than traditional machine learning methods. With the concept of edge computing, we deployed the model on the local embedded system to improve the information transmission and security issues of cloud computing. In order to realize the tracking system, this paper builds a mecanum-wheel vehicle with omnidirectional mobility, and proposes a parallel-cascade PID controller architecture based on the mecanum-wheel vehicle. The fixed distance linear tracking control can be realized through the dual-loop feedback control of distance and yaw angle; moreover, the vehicle slipping which is caused by difference rotation speed can be improved. Finally, through algorithm optimization, controller parameter adjustment, and system integration, an omnidirectional mobile vehicle with recognition and tracking functions is realized. The experiment results indicate that the system is stable and robust during actual operation. [ABSTRACT FROM AUTHOR]

The real time switching signal design and control input are developed to guarantee the passivity and H2 performance of switched systems with interval time‐varying delay and linear fractional perturbations. For the difficulty in real time switching, a synchronous switching on signal and sampled‐data control based on sampling instant is proposed to achieve the mixed performance (passivity/H2) of system under consideration. On the other hand, the sampled‐data controls under arbitrary switching are also considered for the capture anytime and at sampling instant of switching signal, respectively. The proposed LMI conditions can be implemented numerically by Matlab toolbox. Full matrix formulation approach is used to present the main results and improve the conservativeness of the published results. New inequality and Lyapunov–Krasovskii functional are developed to achieve better proposed results in this article. Finally, some numerical examples are illustrated to show the use of our main results. [ABSTRACT FROM AUTHOR]

This paper deals with the H∞ synchronization problem of switched chaotic systems accompanied by a time-driven switching law and its application to secure communications. Based on the Lyapunov stability theory and linear matrix inequality (LMI) and linear matrix equality (LME) optimization techniques, an output feedback controller that guarantees the synchronization of switched master-slave chaotic systems is designed. A chaotic encryption technique that uses synchronization is proposed for securely transmitting a message over public channels. Numerical simulations of both analog and digital security communication systems are conducted to demonstrate the effectiveness of the proposed methods. [ABSTRACT FROM AUTHOR]

Abstract: This paper investigates the robust chaos suppression problem for some classical Rössler systems using the sliding mode controller (SMC). Based on the proportional-integral (PI) switching surface, a SMC is derived to not only guarantee asymptotical stability of the equilibrium points of the Rössler systems but also reduce the effect of noise perturbation to an -norm performance. The parameter matrix necessary for constructing both PI switching surface and the SMC can be easily solved by the linear matrix inequality (LMI) optimization technique. Finally, two illustrative examples are provided to demonstrate the efficacy of the proposed control methodology. [Copyright &y& Elsevier]

Abstract: The aim of this paper is to propose an output coupling and feedback scheme, which is not only to guarantee the asymptotic synchronization between the master and the slave chaotic systems with multiple time-delays but also to attenuate the effects of noise perturbation on the overall error system to a prescribed level in terms of the performance index -norm. The output coupling and feedback gain is derived on the basis of the Lyapunov theory and the linear matrix inequality (LMI) technique. Some numerical examples are given to demonstrate the effectiveness of the main results. [Copyright &y& Elsevier]

A novel technique for transmission of information through visible light communication (VLC) is developed in this study. A light-emitting diode is used as the light source at the transmitting side to send the encrypted information. At the receiving side, a light sensor, OPT-101, is used to receive the light signals that carry the encrypted information. The Arduino Due microcontroller board is used for digital signal processing at both the transmitting and receiving sides. Furthermore, to prevent the transmitted message from being intercepted, two chaotic systems, a master and a slave, with a synchronization controller are designed to obtain the transmitted audio signals. The design enables not only a VLC system with the light transmission path as a straight line (so that data cannot be stolen) but also the encryption of the audio signals with the chaotic system (Rössler system) to enhance data transmission security. The effectiveness of this system is then experimentally verified. [ABSTRACT FROM AUTHOR]

In this paper, the mixed performance and reachable set of uncertain discrete systems with slow variation interval time-varying delay are considered. The original uncertain discrete systems with interval time-varying delay are first transformed into a switched system. Then, the proposed improved results are used to guarantee the stability and reachable set of the uncertain system with slow variation interval time-varying delay. The mixed performance (H2/H∞) can be derived in the same formulation simultaneously. The design scheme of robust switched control is also developed in this paper. The gains of the controller can be designed and switched to achieve stabilization and mixed performance of the system according to the delay value. Some comparisons with published results are made to show the main contribution of the proposed approach. Finally, some numerical examples are illustrated to show the main results. [ABSTRACT FROM AUTHOR]

Study design: Controlled laboratory study. Objectives: To examine characteristics of neck movement at three-dimensional planes for subjects with mechanical neck disorder (MND) and measure cervical range of motion, coupling motion, and calculation of the upper cervical rotation ratio. Background: MND is characterized by symptoms of neck pain, headache, dizziness and limited range of motion (ROM). However, the characteristics of neck movements across the three-dimensional planes in MND patients remain unknown. Methods: Forty participants were recruited, which consisted of twenty-seven subjects with MND and 13 healthy subjects. A three-dimensional electromagnetic motion capture device with custom data analysis software was used to measure the neutral position of the neck and the range of motion of upper and lower cervical spine. Results: The results indicate that subjects with MND had significantly decreased ROM in right rotation (p< 0.05) and extension (p< 0.05) movements compared to the healthy group. Increased coupling motion (p< 0.05) in the rotation plane during cervical flexion was also found in the MND group compared to control group. For rotations in neutral or in flexion positions, rotation to the right showed smaller range of motion compared to rotation to the left. Conclusion: In this study, MND was associated with altered cervical movement patterns with increases in coupling motion. The findings may help to differentiate MND from whiplash-associated disorder. Increasing upper cervical spine rotation mobility may be crucial for treating deficiencies in neck rotation in patients with MND. [ABSTRACT FROM AUTHOR]

Study design: Controlled laboratory study. Objectives: To examine characteristics of neck movement at three-dimensional planes for subjects with mechanical neck disorder (MND) and measure cervical range of motion, coupling motion, and calculation of the upper cervical rotation ratio. Background: MND is characterized by symptoms of neck pain, headache, dizziness and limited range of motion (ROM). However, the characteristics of neck movements across the three-dimensional planes in MND patients remain unknown. Methods: Forty participants were recruited, which consisted of twenty-seven subjects with MND and 13 healthy subjects. A three-dimensional electromagnetic motion capture device with custom data analysis software was used to measure the neutral position of the neck and the range of motion of upper and lower cervical spine. Results: The results indicate that subjects with MND had significantly decreased ROM in right rotation (p< 0.05) and extension (p< 0.05) movements compared to the healthy group. Increased coupling motion (p< 0.05) in the rotation plane during cervical flexion was also found in the MND group compared to control group. For rotations in neutral or in flexion positions, rotation to the right showed smaller range of motion compared to rotation to the left. Conclusion: In this study, MND was associated with altered cervical movement patterns with increases in coupling motion. The findings may help to differentiate MND from whiplash-associated disorder. Increasing upper cervical spine rotation mobility may be crucial for treating deficiencies in neck rotation in patients with MND. [ABSTRACT FROM AUTHOR]