Search

This work investigates the tracking control problem for underactuated mechanical systems. To this end, we develop an extension of the dynamic tube Model Predictive Control (MPC) approach by combining an MPC design, an ancillary energy shaping controller constructed with the Interconnection and Damping Assignment Passivity-Based Control methodology, and an analytical expression of the dynamic tube. In addition, we extend the proposed approach by including the adaptive compensation of a class of unknown disturbances. The stability analysis is presented by employing a Lyapunov approach. The effectiveness of the proposed controller is demonstrated with simulations on two underactuated systems: a two-mass-spring-damper system with uncertain damping and either linear or nonlinear spring; an inertia-wheel-pendulum with unmodeled disturbances.

This paper dealt with the problem of output tracking for neutral Markov jump systems with multiple delays based on generalized non-fragile asynchronous feedback control. Attention is focused on the design of generalized non-fragile asynchronous feedback controller to ensure that the closed-loop system is stochastically stabilization and meet an expected mixed $$ H_\infty $$ and passivity performance index. The modes of devised generalized non-fragile asynchronous feedback controller are assumed to run asynchronously with neutral Markov jump systems, which is described by a hidden Markov model. The sufficient conditions for the solvability of generalized non-fragile asynchronous feedback control problem are obtained based on decomposed free weighting matrices technique and linear matrix inequalities. The usefulness and effectiveness of output tracking based on generalized non-fragile asynchronous feedback controller are demonstrated by a numerical example and a practical example of neutral partial element equivalent circuit.

The problem of mixed $$H_{\infty }$$ and passivity performance analysis is investigated for interfered digital filters under Markovian jumping parameters, time-varying delays and various combinations of quantization and overflow nonlinearities. By virtue of Lyapunov–Krasovskii stability approach, a novel sufficient condition is derived such that the underlying system is stochastically stable and satisfies a prescribed mixed $$H_{\infty }$$ and passivity performance index. In a unified framework, the proposed criterion can be used for the $$H_{\infty }$$ performance, the passivity and the mixed $$H_{\infty }$$ and passivity performance of digital filters. Moreover, the problem is formulated to obtain optimal performance index (i.e. $$H_{\infty } ,$$ passivity and mixed $$H_{\infty }$$ and passivity) of interfered digital filters. At last, two numerical examples and an interfered digital filter with tridiagonal state-space model are applied to demonstrate the effectiveness of the proposed approach.

The performance of mixed $$H_{\infty }$$ and passivity for T-S fuzzy system under the non-fragile memory sampled-data controller is considered in this paper. We construct a non-fragile memory sampled-data controller, which includes a constant signal transmission delay. And by constructing an augment Lyapunov–Krasovskii functional (LKF), taking into account Wirtinger-based integral inequality and the Convex combination technique, we can get a new criteria that mixed $$H_{\infty }$$ and passivity for closed-loop system. Numerical examples are used to demonstrate the effectiveness and superiority of the results.

This paper considers the topic of the observer-based non-fragile mixed passivity and H∞ state feedback control for time-varying delay and norm-bounded parameter uncertainties fuzzy stochastic Markovian jump system subject to quantized measurements. The aim of this paper is to provide a suitable observer-based non-fragile state feedback controller to enhance stochastic stabilization of the closed-loop system and satisfy mixed passivity and H∞ performance. By constructing mode-dependent Lyapunov-Krasovskii functional, novel conditions are achieved in virtue of linear matrix inequalities. Two examples including truck-trailer model are given to illustrate the effectiveness of the developed method.

This paper deals with the event triggered filtering problem for a class of delayed discrete-time Markov jump neural networks, where a resilient filter with parameter uncertainties is adopted. The aim of this paper is to design a suitable filter which ensures that the filtering error system is stochastically stable and satisfies a prescribed mixed passivity and H∞ performance. Sufficient conditions for solvability of such a problem are developed. Based on the obtained conditions, an explicit expression of the desired resilient filter is proposed. Finally, an example is presented to show the usefulness of the proposed scheme.

In this paper, we study the problem of passivity analysis and feedback passification for discrete-time switched systems. Main objectives are to design a switching law and controllers to guarantee the passivity of closed-loop systems. The switching law is designed by introduced mode-dependent persistent dwell time (MPDT). This guarantees each subsystem is with its own PDT, which upgrades the degree of flexibility for constructing switching signal. Further, by using quasi-parameter-varying (QPV) storage functions, a class of QPV output feedback controllers matching different switching period of MPDT is constructed. More importantly, the controllers are allowed to be reduced order by transforming partial measurable state and output directly. This simplifies the overall complexity in the process of passification. Under the proposed switching and control strategies, a non-weighted switched time parameter-dependent passivity index of the closed-loop systems is satisfied, which further illustrates the relationship between switching behavior and passivity. Finally, an example is employed to demonstrate the effectiveness of the presented results.

Numerous studies have identified deficits in the self-monitoring system that are associated with schizophrenia. However, the tasks used in the few previous studies generally involved complex cognitive processes and rarely compared between patients with and without passivity experiences (PE). Here, we examined the deficits in internal motor predictive representation in patients with and without PE, and in healthy controls using a novel paradigm which involved minimal cognitive processes. All participants completed a modified joint position matching (mJPM) task, in which they were required to replicate a voluntary, a passive verbally-cued, and a passive tactile-cued movement under blinded conditions. The absolute difference between the target spot and replicated spot was measured and compared. We hypothesised that if there was a failure in the internal motor predictive representation, patients with PEs would replicate less accurately in the voluntary condition, relative to passive conditions while the healthy controls would be more accurate, and, therefore, significant interactions between groups and conditions would be revealed. Both healthy controls and patients without PEs replicated more accurately in the voluntary condition compared with the passive conditions. The patients with PEs were less accurate in the voluntary condition compared with the passive tactile condition. A significant interaction was observed between patients with vs. without PEs × voluntary vs. passive tactile conditions. The findings suggested the relationship between deficits in motor self-monitoring in the prediction process and PEs, thus showing the need to highlight the link between motor performance and PEs.

This paper deals with the non-fragile state estimator design to study the robust extended dissipativity criterion for a class of discrete-time neural networks (DNNs) involving uncertainties as well as time-varying delay components. The requisite of the proposed problem is to design a proper state estimator such that the dynamics of the corresponding estimation error is extended dissipative having external disturbance and unpredictable fragility performance. By constructing an appropriate Lyapunov–Krasovskii functional (LKF), the sufficient conditions for the extended dissipativity performance of the error system obtained by means of the proposed DNNs and its estimator which includes the $$H_{\infty }$$ performance, $$L_{2}-L_{\infty }$$ performance, passivity and dissipativity performance in a unified framework. The established theoretical results are expressed in terms of linear matrix inequalities (LMIs) that can be easily checked by using the standard numerical softwares. In order to analyze the applicability and effectiveness of the proposed theoretical results, numerical examples including a quadruple tank process (QTP) system model have been illustrated with simulation results.

This paper investigates asynchronous mixed passivity and $$H\infty $$ filter design for fuzzy jump systems with time-varying delays. Firstly, new time delay-dependent stability conditions for the fuzzy Markovian jump systems are obtained by constructing a mode-dependent Lyapunov functional and introducing free weight matrices technique. Secondly, the asynchronous filter is designed via linear matrix inequalities, which can ensure stochastic stability and the mixed passivity and $$H\infty $$ performance of the augmented Markovian jump filtering error system. A numerical example and a single-link robot arm are utilized to show the effectiveness of the method.

Properties of a passive film formed on pure nickel in an anaerobic alkaline solution are investigated by a first-principles calculation and electrochemical experiments in this work, and both results show agreement with each other. The formation energy of nickel vacancies is lower than that of oxygen vacancies in the NiO film, which is consistent with the deduction of the point defect model in which nickel vacancies impart p-type semiconducting character to the passive film, as confirmed by Mott–Schottky analysis. The density of nickel vacancies (approximately 1021 cm−3) in the passive film increases with temperature but decreases with the film-formation potential. The thickness of the passive film increases linearly with the film-formation potential, as verified both by Auger electron spectroscopy and electrochemical impedance spectroscopy. The diffusion coefficient of the nickel vacancies increases from 10−18 to 10−16 cm2/s as the temperature rises from 298 to 348 K, respectively, in experiments using high-field equations and first-principles calculation.

In this article, we investigate the robust passivity and stability analysis of uncertain complex-valued impulsive neural network (UCVINN) models with time-varying delays. Many practical systems are subject to uncertainty in the real-world environments. As a result, we consider the uncertainty of norm-bounded parameters to achieve more realistic system behaviors. By using appropriate Lyapunov–Krasovskii functionals and integral inequalities, sufficient conditions for the robust passivity and global asymptotic stability of UCVINNs are derived by separating complex-valued neural networks into real and imaginary parts. The criteria are given in terms of linear matrix inequalities (LMIs) that can be checked by the MATLAB LMI toolbox. Finally, numerical simulations are presented to illustrate the merits of the obtained results.

This paper investigates the issue of passivity and passification for delayed Markov jump bidirectional associate memory (BAM)-Type neural networks via non-uniform sampled-data control. By utilizing the Lyapunov–Krasovskii functional strategy, a novel delay-dependent passivity criterion is developed with respect to linear matrix inequalities to guarantee the Markov jump delayed BAM neural frameworks to be passive. At that point, in view of the got passivity conditions, the passification issue is further tackled by planning a mode-dependent non-uniform sampled-data controller design is presented. Finally, a numerical example is provided to illustrate the applicability and effectiveness of the theoretical result.

This paper considers the move from passivity to a generative passivity in Merleau-Ponty’s ontology. In The Visible and the Invisible Merleau-Ponty calls this generative passivity a “secondary passivity” and in his passivity lectures he describes it as “passivity without passivism.” The paper argues that this secondary passivity must be understood in terms of an ecart within the phenomena. That is, in terms of a separation and distance which is matrixed and configured within what appears. This is the basis for Merleau-Ponty’s statement in his passivity lectures that “the touchstone of a theory of passivity,” is a “notion of oneiric symbolism,” and why for him passivity is intimately connected to a “primordial symbol.” If the symbolic is so associated with passivity, the symbolic also does not concern origins but is both the ontological limit and divergence in phenomena. This association forces Merleau-Ponty to consider what it means for phenomenological reflection retrace its steps back to an initial event of expression and even whether phenomenology is ultimately served by description. Finally, this paper considers Merleau-Ponty’s attitude toward the literary usages of language as a means of doing a phenomenology of the secondary passivity.

The focus of this paper is to address a novel control technique for stability and transparency analysis of bilateral telerobotic systems in the presence of data loss and time delay in the communication channel. Different control strategies have been reported to compensate the effects of time delay in the communication channel; however, most of them result in poor performance under data loss. First, a model for data loss is proposed using a finite series representation of a set of periodic continuous pulses. To improve the performance and data reconstruction, a holder circuits is also introduced. The passivity of the overall system is provided via the wave variable technique based on the proposed model for the data loss. The stability analysis of the system is then derived using the Lyapunov theorem under the time delay and the data loss. Finally, experimental results are given to illustrate the capability of the proposed control technique.

The interaction between the three-phase voltage source converters (VSCs) and the power grid may cause high-frequency resonant instable problems. Studies have indicated that the non-passivity of VSCs is the main reason that leads to the resonances. The above-mentioned passive means that the equivalent output admittance of the VSC has a positive real part. In this paper, a novel damped Smith predictor is proposed to suppress the resonant instability problem that caused by time delay. The research proved that the proposed Smith predictor can significantly improve the passivity of the VSC by reducing the width of the negative real part at the high-frequencies. Simulation and experimental results demonstrate that the proposed Smith predictor can distinctly improve the robustness of the VSC.

Nonlinear dynamical and time varying parameters of the permanent magnet synchronous generator (PMSG), make it difficult to control. This paper presents a new passivity-based control (PBC) of tidal turbine based PMSG, connected to the grid through a back-to-back converter. The control problem is challenging for at least two reasons. First, the dynamics of the conversion system are described by a highly coupled set of nonlinear differential equations and various uncertainties of the PMSG model. Second, it is preferable to operate this kind of systems at the point of maximum power, which is a nonlinear function. To this end, two kinds of control strategies have been used. A new passivity-based voltage controller (PBVC) design applied to the machine-side, that ensures asymptotic convergence to the MPPT is presented. A proportional integral derivative (PID) is added to design a desired torque dynamic in order to guarantee a fast convergence and stability of the closed loop system, which allows to the PMSG to operate at an optimal speed. Secondly, a classical proportional integral (PI) controllers is applied to the grid-side in order to regulate the DC-Link voltage and to deliver only the active power into distribution network. Finally, the obtained simulation results under MATLAB/Simulink, show that the proposed control strategy ensures stability and fast response of the DC-link voltage and the reactive power generated is extremely minimized.

In this paper, we present two adaptive control approaches to handle uncertainties caused by parametric and modeling errors in a class of nonlinear systems with uncertainties. The methods use the Port-controlled Hamiltonian (PCH) modelling framework and the interconnection and damping assignment passivity-based control (IDA-PBC) control design methodology being the most effectively applicable method to such models. The methods explore an extension on the classical IDA-PBC by adopting the state-transformation, yielding a dynamic state-feedback controller that asymptotically stabilizes a class of underactuated mechanical systems and preserves the PCH structure of the augmented closed-loop system. The results are applied to the underactuated mechanical systems that are a class of mechanical systems with broad applications and are more interesting as well as challenging control problems within this context. The results are illustrated with numerical simulations applied to two underactuated robotic systems; the Acrobot and non-prehensile planar rolling robotic (disk-on-disk) systems.

This paper foucuses on the study of finite-time extended dissipative control for a class of switched nonlinear systems. An event-triggered communication scheme is proposed to reduce the transmitted data of the system state. Sufficient conditions for finite-time extended dissipative control for the switched nonlinear systems are addressed, based on extended dissipative, we can solve the H∞, L2 − L∞, Passivity and (Q, S, R)-dissipativity performance at the same time. T-S fuzzy models are applied to represent the nonlinear subsystems. Linear matrix inequality techniques are used for the design of the fuzzy controller. Finally, numerical examples are presented.

In order to solve the problem of excessive damage to doubly fed induction generator (DFIG) system under the condition of unbalanced voltage, this paper presents an improved coordinated control strategy based on doubly-fed induction generator (DFIG) wind power system, which can solve these problems well. The innovation of this paper is that the parallel grid-side converter (PGSC) uses a passivity-based controller (PBC) based on the Port Control Hamiltonian Dissipation (PCHD) model. Not only can four different control goals be achieved, namely, constant voltage of DC bus voltage, grid-side active power without second harmonics, grid-side reactive power without second harmonics, and grid-side current without negative sequence component, but also to ensure that the balance of stator and rotor current without distortion, the DFIG output power and electromagnetic torque without pulsation. The proposed coordinated control strategy has the characteristics of not changing the control strategy of the rotor-side converter and avoiding complex high-order matrix. The experimental results on the software platform and the hardware platform show that the proposed coordinated control strategy has the advantages of fast response, strong anti-interference ability, high stability, less control parameters.

This paper addresses the problem of asymptotic stability and position tracking in nonlinear teleoperation systems interacting with non-passive operator and environment. A nonlinear control law which is designed based on Interconnection and Damping Assignment Passivity-Based Control (IDA-PBC) scheme, uses the positions and velocities of the joints of manipulators to provide asymptotic stability of tracking errors. Using the Lyapunov–Krasovskii theorem, sufficient conditions are derived in terms of computationally amenable Linear Matrix Inequalities (LMIs), to tune the controller parameters in the presence of asymmetrical varying time delay in the communication channel. The proposed controller synthesis methodology requires no known passive part in the dynamical model of interaction forces. Moreover, using the integral control notion, the asymptotic stability of the synchronization errors is assured. Comparative simulation results are presented to demonstrate the superiority of the proposed method compared to some rival ones. Finally, experimental results from a laboratory teleoperator are reported to confirm the applicability of the introduced scheme.

The studies conducted on the prevalence of the lifelong form of anorgasmia in Iran indicate clear differences in its prevalence in women in Iranian culture compared to western culture. The authors have attributed such differences to the differences in assessment tools, sample size, and poor study methods, as well as cultural barriers to the use of questionnaires, and the effects of culture on sexual disorders. In this article this issue has been formulated from a cultural concept of passivity. In Iranian culture, passivity is regarded as one of the dominant roles of women in sex, which can be called “The Queen’s Passivity”. Indeed, this special kind of passivity before men has certain privileges for the woman as a queen. This is “passivity resulting in authority”, which is an important feature of this culture and all evidence suggests that passivity and anorgasmia accompany each other in this culture and the profound meaning of its suffering should be somewhat sought in the “man king-queen’s passivity” relationship, which has denied many Iranian women the experience of pleasure of orgasm for thousands of years. This hypothesis has been explained by making reference to important cultural and religious resources in Iranian culture in this article and it has been argued that if anorgasmia can be better explained culturally, then this problem should not be considered a psychiatric disorder. This point is not taken into account in DSM5 diagnostic criteria for anorgasmia and the lack of attention to this issue can be one of the reasons for the greater report of anorgasmia in Iran.

In this paper, we study the problem of passivity analysis of fractional-order neural networks (FONNs) with a time-varying delay. By using the Razumikhin fractional-order theorem, we first derive an improved sufficient criterion for asymptotic stability of FONNs with a bounded time-varying delay. Then, based on the proposed stability criterion and some auxiliary properties of fractional calculus, a delay-dependent condition is established to ensure the passivity of the considered system. These conditions are order-dependent and in the form of linear matrix inequalities, which therefore can be efficiently solved in polynomial time by using the existing convex algorithms. Some numerical examples are provided to show the effectiveness of the obtained results.

This paper addresses the passivity problem for delayed non-autonomous discrete-time inertial neural networks (NDINN), including the discrete-time switched inertial neural networks (DSINN) with state-dependent discontinuous right-hand side as its special case. First, we take a linear transformation to transform the original network into first-order difference equations. Second, by utilizing the Lyapunov direct method and with the help of the property of maximum singular value, we present a passivity criterion for the NDINN with delay-dependent linear matrix inequalities. Combining with the characteristic function method, the proposed analytical approach for NDINN is further extended to the DSINN. Finally, two simulation examples validate the efficacy of the analytical results.

This the first time that the problem of global asymptotic stability analysis, and mixed $H_{\infty }$ and passive control for a class of control fractional-order nonlinear systems has been studied in this paper. By using the Lyapunov direct method and some properties of fractional calculate, we propose sufficient conditions to ensure the unforced system to be asymptotically stable with mixed $H_{\infty }$ and passivity performance level. Further, mixed $H_{\infty }$ and passive control design with an appropriate gain matrix has been derived to achieve the stabilization for fractional-order system with nonlinear perturbations and order $0 < \alpha < 1$ . These conditions are in the form of linear matrix inequalities, which therefore can be efficiently solved by using existing convex algorithms. The effectiveness of our results is illustrated through three numerical examples.

This article considers the passivity control of chaotic systems under the presence of uncertainties and perturbations. Passivity-based controllers are applied that can achieve stabilization at any equilibrium point of the system, or synchronization. The control laws that are introduced consist of two parts. The first part is implemented to achieve the necessary conditions for the application of the passivity method, and the second makes the system settle at its equilibrium points in the control case, or to achieve synchronization in the second case. Furthermore, numerical, as well as microcontroller implementations, by using Arduino, are performed to illustrate the effectiveness and practicality of the proposed method.

In “The rise of the robots and the crisis of moral patiency”, John Danaher argues that the rise of AI and robots will dramatically suppress our moral agency and encourage the expression of moral passivity. This discussion note argues that Danaher needs to strengthen his argument by supporting two key assumptions, that (a) AI will otherwise be friendly or neutral (instead of simply destroying humans), and that (b) humans will largely succumb to the temptation of over-relying upon AI for motivation and decision-making in their personal lives.

The effect of solution annealing temperature on microstructure and the corresponding AC (alternating current) corrosion behavior was investigated by electrochemical impedance spectroscopy, polarization curve, Mott–Schottky curve and immersion test. With or without AC application, the 2507 SDSS (super-duplex stainless steel) samples annealed at various temperatures exhibit a difference in corrosion resistance. Among them, the corrosion resistance first increases and then decreases as the annealing temperature increases, that is, the 2507 SDSS annealed at 1060 °C has the optimum corrosion resistance, followed by the specimen annealed at 1000 °C, and finally the specimen at 1120 °C. The variation trends of Rct, Rf and ip can verify the above law. The σ phase and an excessive amount of α phase within the microstructure can decrease the corrosion resistance. Additionally, the stability and protective property of passive film formed on the electrode surface is associated with the microstructure of 2507 SDSS. An imposed AC can decrease the passivity of 2507 SDSS and damage the film formed on the sample surface. Furthermore, the corrosion rate and pitting sensitivity of the SDSS increase with the increasing AC current density.

This work aims to study the problem of output strictly passive $$H_\infty $$ control for discrete-time linear switched singular systems. By using multiple storage functions and iteration technique, some sufficient conditions are obtained based on output strict passivity and proportional plus derivative state feedback, which can guarantee that the closed-loop systems are normal and stable and satisfy a given $$H_\infty $$ performance. Proportional plus derivative state feedback sub-controllers with explicit expressions are designed. Proportional plus derivative state feedback can not only eliminate impulse phenomena, but also eliminate state jumps caused by incompatible initial conditions of subsystems at switching instants. A numerical example is given to verify the applicability of the results.

The passivity, low power consumption, memory characteristics and nanometer size of memristors make them the best choice to simulate synapses in artificial neural networks. In this paper, based on the proposed associative memory rules, we design a memristor neural network with plasticity synapses, which can perform analog operations similar to its biological behavior. For the memristor neural network circuit, we also construct a relatively simple Pavlov’s dog experiment simulation circuit, which can effectively reduce the complexity and power consumption of the network. Some advanced neural activities including learning, associative memory and three kinds of forgetting are realized based on the spiking-rate-dependent plasticity rule. Finally, the Simulation program with integrated circuit emphasis is used to simulate the circuit. The simulation results not only prove the correctness of the design, but also help to realize more efficient, simpler and more complex analog circuit of memristor neural network and then help to realize more intelligent, smaller and low-power brain chips.

The problem of controlling the relative position and velocity in multi-spacecraft formation flying in the planetary orbits is an enabling technology for current and future research. This paper proposes a family of tracking controllers for different dynamics of Spacecraft Formation Flying (SFF) in the framework of port-Hamiltonian (pH) systems through application of timed Interconnection and Damping Assignment Passivity-Based Control (IDA-PBC). The leader–multi-follower architecture is used to address this problem. In this regard, first we model the spacecraft motion in the pH framework in the Earth Centered Inertial frame and then transform it to the Hill frame which is a special local coordinate system. By this technique, we may present a unified structure which encompasses linear/nonlinear dynamics, with/without perturbation. Then, using the timed IDA-PBC method and the contraction analysis, a new method for controlling a family of SFF dynamics is developed. The numerical simulations show the efficiency of the approach in two different cases of missions.

Handling loads with small swings is difficult for a 3-dimensional overhead crane due to its hard nonlinearity. Moreover, the nonlinear dynamics increases the complexity of the required feedback, thus making the closed-loop system sensitive to a variation in the cable length that negatively influences the damping feature. To address these problems, a significant storage function characterized by the desired damping is constructed based on passivity. Consequently, a nonlinear controller is delivered by enforcing the coupled–dissipation inequality, thus drastically increasing the damping of the closed-loop system. In particular, new coupled–dissipation signals are fabricated to augment the coupling between the trolley movement and the payload sway. Due to its very simple structure that excludes the cable length, the proposed controller is robust to unknown cable lengths and easy to implement. In the frame of the Lyapunov theory, LaSalle’s invariance principle is applied to illustrate the corresponding stability. The effectiveness of the proposed control on improving the system performance is verified through simulation results.

This paper is devoted to studying the issue of passive fuzzy controller design for a class of nonlinear distributed parameter systems represented by semi-linear parabolic partial differential equations. The main objective of this paper is to develop two kinds of fuzzy controllers, one is static output feedback controller (SOFC), the other is dynamic output feedback controller (DOFC), which can guarantee both the stability and passivity of the designed closed-loop system. For the purpose of achieving the anticipated target, in this paper, the semi-linear parabolic PDE systems are assumed to be exactly represented by a Takagi-Sugeno (T-S) fuzzy parabolic PDE model. Furthermore, two examples are given to demonstrate the effectiveness of the controller design scheme.

This paper investigates the finite-time robust passive control of nonlinear discrete time-delay systems via static output feedback. The considered discrete time-delay system has uncertain terms which are due to parametric uncertainties and exogenous disturbances. The disturbances are unknown time-varying signals with known upper bounds. In order to design the suitable control law, some sufficient conditions (in terms of some matrix inequalities) should be satisfied. These conditions are derived using the Lyapunov–Krasovskii functional approach. The passivity property of the closed-loop system is also presented in the form of matrix inequalities. These conditions are then converted to linear matrix inequalities (LMIs), and the gain of the controller is obtained from the feasibility testing of the resulting LMIs. Finally, the efficiency of the proposed controller is demonstrated through computer simulations for numerical and practical (Chua’s circuit) examples.

Carbonation results in a decrease in the pH of the cementation matrix when CO2(g) from the environment diffused into the concrete structure that can cause the loss of passivity condition on the reinforcing steel surface and leads to early failure of concrete by corrosion attack. There are several monitoring techniques to evaluate the process of lowering the pH in the concrete, named carbonation depth progress. In this research, an electrochemical AC impedance spectroscopy (EIS) technique has been used as an effective laboratory tool for monitoring the evolution of the carbonation progress. A comparison with the traditional phenolphthalein colorimetric technique was also discussed here. Particularly, monitoring is achieved by measuring the change in electrical resistance (Rpo) and capacitance (Cpo) of the concrete bulk, which is obtained from the semicircle at high-frequency region of a typical EIS diagram. According to the EIS results, carbonation progress was observed by a significant increase in the diameter of the semicircle, thus demonstrating the increase in resistivity of ions transmission due to blockade of pores by precipitation of CaCO3 compounds. Furthermore, it was possible to predict the specific time at which the carbonation front reaches the steel-rebar interface at low frequency region and possibly starting a considerable corrosion attack. Finally, the results suggested that EIS technique could be considered a practical tool for evaluating the carbonation progress of reinforced concrete structures without causing structural damage, in addition to the sensitivity of this technique with sufficient accuracy to predict the activation of the reinforcing steel.

A fractional frequency transmission system (FFTS) is the most competitive choice for long distance transmission of offshore wind power, while the Hexverter, as a newly proposed direct AC/AC converter, is an attractive choice for its power conversion. This paper proposes a novel control scheme characterizing the global stability and strong robustness of the Hexverter in FFTS applications, which are based on the interconnection and damping assignment passivity-based control (IDA-PBC) methodology. Firstly, the frequency decoupled model of the Hexverter is studied and then a port-controlled Hamiltonian (PCH) model is built. On this basis, the IDA-PB control scheme of the Hexverter is designed. Considering the interference of system parameters and unmodeled dynamics, integrators are added to the IDA-PB controller to eliminate the steady-state error. In addition, the voltage-balancing control is applied in order to balance the capacitor DC voltages to obtain a better performance. Finally, the simulation results and experimental results are presented to verify the effectiveness and superiority of the IDA-PB controller.

This paper investigates the problem of robust decentralized fault-tolerant resilient control for fractional-order large-scale interconnected uncertain system, and the problem considered here is subject to mixed H∞ and passivity performance constraint, external disturbances, controller perturbations and control input saturation. Based on the Lyapunov approach, the sufficient conditions are derived in terms of linear matrix inequalities to ensure the asymptotic stabilization of the fractional-order large-scale system with a prespecified mixed H∞ and passivity performance index. The main objective of this work is to design a robust decentralized fault-tolerant resilient controller which compensates both actuator fault and input saturation in its design for obtaining the required result. Finally, a numerical example is included to illustrate the effectiveness of the designed control law. The simulation results reveal that our proposed controller not only can effectively deal with actuator faults, but also has very good robustness for input saturation and external disturbances.

This proposed research work is devoted to the problem of passivity analysis for uncertain BAM neural networks with leakage, discrete and distributed delays using novel summation inequality. The uniqueness of this proposal is from the deliberation of an advanced inequality (i.e., novel summation inequality) which is novelty than the famous Jensen inequality engaged in the framework of discrete-time neural networks systems. For the investigation of continuous-time neural networks, Wirtinger-based integral inequality was currently engaged whereas novel summation inequality is for discrete-time neural networks. With the assistance of Lyapunov-Krasovskii functional, some conditions are derived and entrenched in terms of linear matrix inequalities which can be easily checked by some available software packages. Two benchmark examples are proposed and lead better upper bounds for the tolerable time delay than existing literatures to show the fruitfulness and efficacy of the proposed work.

This study addresses the sliding mode control (SMC) issue for time-delay Markovian jump singular systems. Firstly, the T-S fuzzy mode is established for the system. Secondly, novel integral-type fuzzy sliding surfaces are constructed for accommodating the system’s model characteristics. Thirdly, free-weighting matrix technique combined with Lyapunov-Krasovskii functional are used for guaranteeing the admissibility and passivity of the system. Finally, the effectiveness of the proposed approach is verified by simulation result.

This paper is focused on a finite-time reliable control design for nonlinear quadrotor attitude dynamic model against the actuator faults and external disturbances. By the utilization of an appropriate Lyapunov–Krasovskii functional, a finite-time performance analysis criterion is derived to obtain the robust reliable tracking control design for quadrotor dynamic model. Then, a fault-tolerant tracking control is designed such that the attitude of the quadrotor is reliable in the sense that it is finite-time bounded and satisfies the suggested mixed $$H_\infty $$ and passivity performance index under given constraints. Also, the finite-time fault-tolerant controller gain is derived by solving the obtained linear matrix inequalities based on the convex optimization technique. Finally, simulation results are provided to verify the effectiveness and robustness of the proposed control design law.

In this paper, the locally fixed-time and globally fixed-time stabilization problems for the port-Hamiltonian (PH) systems via the interconnection and damping assignment passivity-based control technique are discussed. The definitions of fixed-time stability region (or region of attraction) and fixed-time stability boundary are given in this paper. From this starting point, the sufficient condition of globally fixed-time attractivity of a prespecified locally fixed-time stability region is obtained. Combining the locally fixed-time stability and the globally fixed-time attractivity of a prespecified locally fixed-time stability region, the globally fixed-time stabilization problem for PH system is effectively solved. Furthermore, the globally fixed-time control scheme independent of locally fixed-time stability region has also been derived by constructing a novel Lyapunov function. A illustrative example shows that the results obtained in this paper work very well in fixed-time control design of PH systems.

Herein, the effect of high chloride ion (Cl−) concentration on the corrosion behavior and passive film breakdown of 13Cr martensitic stainless steel under CO2 environment was demonstrated. The Cl− concentration was varied from 30 to 150 g/L and cyclic potentiodynamic polarization was conducted to investigate the influence of the Cl− concentration on the corrosion potential (Ecorr), passive breakdown potential (Epit), and repassivation potential (Erep). The results of the polarization curves revealed that 13Cr stainless steel is susceptible to pitting under high Cl− concentration. The passive breakdown potential and repassivation potential decreased with the increase of Cl− concentration. The semiconducting behavior of the passive film was investigated by Mott-Schottky analysis and the point defect model (PDM). It was observed that the iron cation vacancies and oxygen vacancies were continuously generated by autocatalytic reactions and the higher Cl− concentration resulted in higher vacancies in the passive film. Once the excess vacancies condensed at the metal/film interface, the passive film became locally detached from the metal, which led to the breakdown of the passive film.

Willis metamaterial enables exotic manipulations of acoustic waves with a precise combination of bulk modulus, mass density, and Willis parameters. While the realization of unrestricted and completely decoupled constitutive parameters would extend the horizon of future applications, the restriction of passivity and reciprocity dictate a hard bound in the values of achievable polarizabilities and correlations between them. Here, we break the bound of passivity and reciprocity by instituting a basis and independent kernel for each constitutive polarization in a virtualized metamaterial platform, active metamaterials realizing artificial polarization with the digital convolution. We demonstrate decoupled control of all four constitutive parameters in a nonreciprocal regime, at the same time achieving values of polarizabilities beyond the passivity limit. Broadband, flat-response nonreciprocal Willis coupling is also demonstrated with analytically designed causal frequency dispersion. Our approach will be useful for nonreciprocal wave manipulation and communication for broadband operation. Metamaterials are designed to control unconventional wave properties in acoustic systems with a range of applications such as acoustic cloaking. Here, the authors design an active acoustic Willis metamaterial that can realize decoupled polarizabilities beyond the bound of passivity and reciprocity.

Teleoperation systems have been presented to handle objects in environments in which the presence of operators are impracticable, unsafe or less effective. In this paper, a passive control strategy employing the new outputs to state synchronization of the master and slave robots is developed to attain position coordination during contact tasks. The proposed control scheme includes position signals plus force signals. However, force measurement in such applications is a major limitation. Therefore, a modified force estimation algorithm is proposed to predict external forces applied on the master and slave robots. The closed-loop bilateral teleoperation system is investigated by employing Lyapunov stability criteria. Finally, the experimental results demonstrate the efficiency of the proposed control scheme. It is observed that, in the presence of the estimated external forces in the control scheme, the slave robot follows the master position in both free and contact motion, and force reflecting occurs properly as well. Moreover, it is verified that the external forces are estimated appropriately through the proposed force estimation algorithm.

The tests were performed using a new equipment, built to simulate aqueous erosion and monitor its electrochemical behaviour. This test was called electrochemical slurry erosion wear method. In this equipment, it is possible to measure the effect of simultaneous erosion wear and electrochemical tests on the passive film behaviour. This kind of test on titanium was not found in the literature review, until now. The aim of this study was to analyse the behaviour of the passive titanium oxide layer, employing polarization curves simultaneously to the slurry erosion wear, unprecedented in the study of titanium passivity under erosive wear, varying the stirring speed and amount of erodent. Therefore, the hydrodynamic shear stress incurred under different stirring speed conditions exerts influence on the corrosion resistance of commercially pure titanium (Ti–Cp).

The passivity-based controller is one of most widely-used controllers for robot manipulators. Since it strongly exploits the system properties, it does not produce unnecessarily large control effort and has inherent robustness against plant uncertainty and disturbance. This paper presents an inner-loop controller which can enhance the robustness of the passivity-based tracking controllers. The inner-loop controller developed in this paper robustly estimates the lumped disturbance, which is defined by the effect of plant uncertainty and external disturbance, and generates a compensating signal so that the closed-loop system consisting of the uncertain robot, disturbance observer, and passivity-based controller behaves like the nominal closed-loop system composed of the nominal model of the robot and the passivity-based controller. It is seen that the tracking error can be made arbitrarily small by choosing the controller parameters appropriately and the performance of the proposed controller is validated through numerical simulations.

This paper proposes a new control framework for a cooperative robotic system which consists of two manipulators to grasp and handle an object with known geometry. Based on passive decomposition approach, the dynamics of the cooperative system are decomposed into the shape and locked systems, considering uncertainty in the dynamics of the robots. Two higher-order sliding mode controllers are designed for them and are tuned by genetic algorithm in the form of an optimization problem. Using the passivity property of passive decomposition approach, the proposed new higher-order sliding mode controllers ensure passivity of the closed loop system. Stability and convergence of the tracking errors are proved by defining a Lyapunov function and using Barbalat’s lemma. Eventually, the comparative simulation results confirmed that the proposed control scheme works well and as expected, works better than the classical sliding mode controllers.

Comparative studies of precipitation-hardening corrosion-resistant nickel-base alloys used in the oil and gas industry are conducted. Corrosion-electrochemical properties of EP718 and Inconel 718 alloys are studied, and composition and microstructure are analyzed. It is observed that the passivity of these alloys may be affected significantly by the amount and composition of nonmetallic inclusions. It is demonstrated that these alloys may be used as analogs.

This paper studies the passivity of the T–S fuzzy singular system with randomly occurring uncertainties via the event-based sliding mode control. The sliding surface function is designed such that the resulting sliding mode dynamics can be expressed by the considered system. Some sufficient conditions are proposed to guarantee the sliding mode dynamics is generalized admissible and robustly passive. Under the aperiodic sampled-data environment, the sliding mode control law is proposed via the event-triggered method. It guarantees that the state trajectory of the system can be driven onto the predefined sliding surface in a finite time and keep it forever. Finally, three examples are given to demonstrate the feasibility and superiority of the design method.

The control problem for linearised three-dimensional perturbations about a nominal laminar boundary layer over a flat plate (the Blasius profile) is considered. With a view to preventing the laminar to turbulent transition, appropriate inputs, outputs, and feedback controllers are synthesised that can be used to stabilise the system. The linearised Navier–Stokes equations are reduced to the Orr–Sommerfeld and Squire equations with wall-normal velocity actuation entering through the boundary conditions on the wall. An analysis of the work-energy balance is used to identify an appropriate sensor output that leads to a passive system for certain values of the streamwise and spanwise wavenumbers. Even when the system is unstable, it is demonstrated that strictly positive real feedback can stabilise this system using the special output.