Iterative learning fault-tolerant control for discrete-time nonlinear systems subject to stochastic actuator faults

This paper is concerned with an iterative learning fault-tolerant control strategy for discrete-time nonlinear systems where actuator faults arbitrarily occur. First, the stochastic faults occurring in multiplicative and additive manner are considered. Then, statistical behaviors of both faults-corrupted control signals from the actuator to the plant and faults-free ones from the iterative learning controller to the actuator are analyzed. Meanwhile, sufficient conditions of convergence for the proposed strategy are established by resorting to the time-weighted norm technique. Finally, two numerical examples are provided to illustrate the effectiveness and reliability of the proposed results. Both theoretical analysis and simulations indicate that the developed strategy is satisfactory in preserving decent tracking accuracy of the addressed systems subject to actuator faults.

Adaptive Fault-Tolerant Control of a Hybrid VTOL UAV against Actuator Faults and Model Uncertainties under Fixed-Wing Mode

This paper proposes an adaptive fault-tolerant control strategy for a hybrid vertical take-off and landing (VTOL) unmanned aerial vehicle (UAV) to simultaneously compensate actuator faults and model uncertainties. With the proposed adaptive control schemes, both actuator faults and model uncertainties can be accommodated without the knowledge of fault information and uncertainty bounds. The proposed control scheme is constructed with two separate control modules. The low-level control allocation module is used to distribute the virtual control signals among the available redundant actuators. The high-level control module is constructed with an adaptive sliding mode controller, which is employed to maintain the overall system tracking performance in both faulty and uncertain conditions. In the case of actuator faults and model uncertainties, the adaptive scheme will be triggered to generate more virtual control signals to compensate the virtual control error and maintain the desired system tracking performance. The effectiveness of the proposed control strategy is validated through comparative simulation tests under different faulty and uncertain scenarios.

Control Signal Analysis of Four Ring Space Stabilized Platform

In order to build a four ring space stable platform using free rotor gyroscope, the spatial layout of gyroscope and frame axis should be briefly analyzed, and the installation shafting should be orthogonal or perpendicular to each other to facilitate control and decoupling. On this basis, through the sensitive angle analysis of gyro and frame shafting, the control signals acting on each frame are deduced. Finally, through the physical design of the control loop of the space stability platform, the correctness of the research method and design form is demonstrated, which has theoretical guiding significance for the design of the space stability control loop.

A Switched Capacitor Memristor Emulator using Stochastic Computing

Due to the increased use of memristors, and its many applications, the use of emulators has grown in parallel to avoid some of the difficulties presented by real devices such as variability and reliability. In this paper, we present a memristive emulator designed using a Switched Capacitor (SC), this is, an analog component/ block and a control part or block implemented using stochastic computing (SCo) and therefore fully digital. Our design is thus a mixed signal circuit. Memristor equations are implemented using stochastic computing to generate the control signals necessary to work with the controllable resistor implemented as switched capacitor.

Adaptive multilayer management remotely operated underwater vehicle

В статье рассматривается самоорганизующаяся адаптивная система управления телеуправляемыми необитаемыми подводными аппаратами. Адаптивная нейронная система многослойного управления построена по принципу декомпозиции мультичастотного набора входных сигналов, формируемых в адаптивном джойстике управления. Декомпозиция наборов последовательностей управляющих сигналов проходит процедуру трешолдинга, разделения по оценкам спектра мультичастотного сигнала управления. Каскадный алгоритм построен по принципу интерполяции и децимации коэффициентов фильтра. Трешолдинг реализуется свёрткой форматного кадра управляющего сигнала с коэффициентами всплеск формирующего фильтра в базисе всплесков Добеши. Интерполяция коэффициентов фильтра происходит сдвигом частоты, децимация схлопыванием коэффициентов фильтра. Спектральные оценки, построенные по среднеквадратическому значению спектра, укладываются в спектральный радиус нормированного сигнала и формируют матрицу математического ожидания адаптивного сигнала управления. Реакции пилота телеуправляемого необитаемого подводного аппарата формируют управляющие сигналы в трёх плоскостях с заданными скоростями и моментами. Трешолдинг в базисе всплесков позволяет формировать сигналы управления с оптимальной крутизной выходной характеристики, что позволяет отказаться от необходимой ручной регулировки мощностей движителей двигательно-рулевого комплекса, при реализации полуавтоматичеcкого и автоматического управления. Обратная связь системы управления по наблюдаемой динамике позволяет реализовать функцию автопилота, с учётом заданных критериев качества. The article discusses the self-organizing adaptive system management remotely operated underwater vehicle. Adaptive neural system of multilayer control is built on the principle of decomposition of multi-frequency set of input signals generated in adaptive joystick of management. The decomposition of the sets of control signal sequences undergoes the procedure of tresholding, separation by estimates of the spectrum of the multi-frequency control signal. The cascade algorithm is based on the principle of interpolation and decimation of filter coefficients. Tresholding is implemented by convolving the format frame of the control signal with wavelet coefficients of the forming filter in the basis of Dobeshi wavelet. Interpolation of filter coefficients occurs by frequency shift, decimation by collapse of filter coefficients. Spectral estimates based on the standard value of the spectrum fit into the spectral radius of the normalized signal and form a matrix of mathematical expectation of the adaptive control signal. The reactions of the pilot of a remotely operated underwater vehicle form control signals in three planes with given speeds and moments. Tresholding in the basis of wavelets allows you to generate control signals with an optimal slope of the output characteristic, which allows you to abandon the necessary manual adjustment of the powers of the propulsion engines of the engine-steering system, when implementing semi-automatic and automatic control. Feedback of the control system according to the observed dynamics allows implementing the autopilot function, taking into account the specified quality criteria.

Bringing It All Together

The main goal of the article “The Neural Foundations of Aesthetic Appreciation” was to bring together the available evidence on the neural underpinnings of aesthetics from neuroimaging and neurology and offer an integral interpretative model. The authors relate how they wanted to explain how aesthetic appreciation was related to brain activity and why some studies had found that activity in some regions and other studies had found it in other regions. The authors proposed that there might be at least two stages of appreciation. The first stage is the formation of an initial impression. It involves perceptual processes interacting with attentional control signals and is mediated by a fronto-parieto-occipital network. The second stage is a deeper evaluation of the image and involves affective processes, searching for meaning, recalling personal experiences, and activating knowledge stored in memory.

Study on the Lower Extremity Rehabilitation Device RHleg

<p class="0abstract">This paper introduces a device to support lower extremity rehabilitation for stroke patients. First, the device's mechanical structure has been presented; the device has a simple structure and fully meets the exercise function for the patient. The equipment is controlled by control and monitoring software, which is designed from Visual Basic software. The control circuit is the Arduino 2560 circuit, responsible for receiving the angle sensor signal and measuring the current during operation. In addition, the control circuit provides control signals to the actuator and communicates with the software using the rs232 cable. Next, the mathematical model of the device has been established, and we use MatLab software to simulate the response of the device to the PID controller. Simulation results for fast response time and slight overshoot. Finally, an experiment on volunteers was conducted, the results showed that the device was stable and safe to operate. Thus, the RHleg device has been successfully designed and manufactured, tested on volunteers with good results, and this is the basis for us to continue moving towards patient testing.</p>

Hybrid Decentralized Nonlinear Control System for Manipulation Robot with Input Saturations

The paper is devoted to consideration of the problem of constructing a discrete-continuous decentralized nonlinear combined control system for two-link robotic manipulator with restrictions in control signals. The mathematical model of the manipulator is presented as a two-channel dynamic plant with nonlinear cross-links. As methods for solving this problem V. M. Popov’s hyperstability criterion and the conditions of L-dissipativity are used. With the help of simulation, the quality of the proposed control system is shown. The results obtained in article may be useful for construction the control systems for manipulators with many degrees of freedom and also for control various mechanical systems.

Method of Formation of Reference Control Signals for Redundant Manipulators

The paper is devoted to preservation of dynamic control accuracy of working tools of multilink manipulators when they move along arbitrary spatial trajectories, taking into account the design limits in all degrees of freedom and special cases of position of their links. Preservation of control accuracy is proposed to be ensured by eliminating reach of all degrees of freedom of the manipulators to the limits and to indicated special positions, characterized by ambiguity in solving the inverse kinematic problems of the manipulators, as well as excluding the reach of their working tools to boundaries of working area due to use of a redundant degree of freedom when approaching indicated undesirable positions. The performed simulation has confirmed efficiency of the proposed method.