Output Delay Research Articles

Delayed finite-dimensional observer-based control of 1D parabolic PDEs via reduced-order LMIs

Recently a constructive method was introduced for finite-dimensional observer-based control of 1D parabolic PDEs. In this paper we present an improved method in terms of the reduced-order LMIs (that significantly reduce the computation time) and introduce predictors to manage with larger delays. We treat the case of a 1D heat equation under Neumann actuation and non-local measurement, that has not been studied yet. We apply modal decomposition and prove L2 exponential stability by a direct Lyapunov method. We provide reduced-order LMI conditions for finding the observer dimension N and resulting decay rate. The LMI dimension does not grow with N. The LMI is always feasible for large N, and feasibility for N implies feasibility for N+1. For the first time we manage with delayed implementation of the controller in the presence of fast-varying (without any constraints on the delay-derivative) input and output delays. To manage with larger delays, we construct classical observer-based predictors. For the known input delay, the LMIs’ dimension does not grow with N, whereas for unknown one the LMIs dimension grows, but it is essentially smaller than in the existing results. A numerical example demonstrates the efficiency of our method.

Concealed Automated Trash Bin with Shredder for Solid Wastes

The common difficulty in populated developing countries like the Philippines is inappropriate waste management practices. The improper use of waste bins and waste segregation are some of those. One of the major causes is the irresponsibility of the people. As expected, the consequences are environmental and health risks experienced by people. The countermeasure to minimize these risks is the solution proposed by people, particularly the development of an automated segregation system. The waste bins are designed to be concealed to conserve space, slow down the decomposition rate and reduce the foul odor of waste. The design is fully automated to minimize direct contact with the waste. The classifying section is capable of collecting and segregating waste using a gripper, servo motors, ultrasonic, capacitive, and photoelectric sensors. To conserve power, the segregated waste is held in a storage bin prior to shredding. Shredded waste is routed to their respective transport bins for collection after shredding.The ultrasonic sensors provide data about the capacity of the transport bins and allow the GSM module to send an SMS informing the concerned authority regarding the bins’ status. These messages facilitate easier waste collection. Two tests were conducted to determine the performance of the prototype: response-time and garbage level detection tests. The result shows that the prototype performed well and can successfully achieve the desired function. It took 23.745 and 2.711 seconds to collect and segregate the waste, respectively. Likewise, the monitoring system successfully expedited the checking of the waste bins. However, it is recommended to include quality of output and SMS delay tests. These tests can improve the overall performance of the prototype.

Surface engineering boron/graphite fluoride composite with enhanced ignition and combustion performances

Boron (B) shows great potential applications in the military and aerospace industry due to its high calorific value. However, the reactivity is limited by the inert oxide layer (B2O3) that covers the B particles. Herein, nano-Al, and Fluorographene (FG) are employed as coating materials to enhance the ignition and combustion efficiency of boron. When graphite fluoride (GF) was utilized as an oxidizer (the B/GF mass ratio is 1:9), the maximum heat release of B@nano-Al/GF (∼5.6 kJ/g) and B@FG/GF (∼5.4 kJ/g) were markedly higher than that of raw B/GF (∼2.5 kJ/g), ascribed to the self-activation effect of the coating layer. On this basis, the combustion experiments were performed and their performances were compared and studied. Specifically, the ignition delay time of B@nano-Al/GF and B@FG/GF was decreased to 320 ms 262 ms, respectively, compared with that of raw B/GF (380 ms) with 15 W laser power. This is consistent with the ignition burning test, where the B@6%nano-Al/GF and B@2%FG/GF have higher flame height than raw B/GF. However, the maximum pressure and pressurization rate decreased for B@6%nano-Al/GF and B@2%FG/GF because of the reduced amount of gas caused by decreased boron content. Additionally, the effects of the B/GF mass ratio (1:9, 2:8, 3:7, 4:6) on the combustion performances of composites were fully studied. The pressure output, combustion reaction, and ignition delay time are reduced with B/GF mass ratios increased. This work could provide a general approach to improve the ignition and combustion performance of boron.

High-order sliding mode-based synchronisation of fractional-order chaotic systems subject to output delay and unknown disturbance

This work deals with chaos synchronisation. One of the commonly used methods is the master-slave configuration, where the response of the chaotic receiver (slave) system must converge to the chaotic trajectory of the transmitter (master). The major problem with this configuration is the delay that occurs during the transmission of the drive signal from the master to the slave, which can degrade the synchronisation. The objective of this paper is to propose a solution to the synchronisation problem of nonlinear fractional-order chaotic systems in the presence of a transmission delay at the output and unknown disturbance. The proposed approach consists of combining a fractional high-order sliding mode observer (FHOSMO) and a predictor arranged in a cascade to compensate for the delayed transmission signal from the transmitter to the receiver. The observer permits to estimate the delayed states and the delayed total disturbance (uncertainties and external disturbances) in finite time. These estimates are injected into the predictor to obtain the estimated states at the current time. The finite time convergence of the proposed method is established. The numerical simulations illustrate the theoretical results and the performance of the proposed method. The proposed synchronisation method is compared with other synchronisation methods using the chattering free sliding mode approach such as the fractional first-order sliding mode observer using the continuous function instead of the discontinuous sign function and the fractional second-order sliding mode observer. In addition, a conventional first-order sliding mode observer with the sign function is also considered.

Design Of Monitoring System of Height, Weight and Body Mass Index Using Android-Based Nodemcu ESP8266

Generally, height and weight measurements are carried out separately as well as to determine the Body Mass Index must be calculated manually using specific formulas that not everyone understands, so it is difficult to know whether the body has reached a normal number or not. This study will provide suggested solutions to support the body to be healthy in measuring devices and android applications, for height measurement using ultrasonic sensors, weight using loadcell sensors and NodeMCU ESP8266 as data processors. The results of measuring height and weight appear on an LCD, the results of Body Mass Index (BMI) and the recommended solutions to meet standard body numbers in calculating BMI appear on the android application. Based on the results of the tests carried out, it is known that designing a measuring instrument with NodeMCU ESP8266 based on Android has been successfully carried out. The measuring instrument by implementing the Ultrasonic Sensor HC-SR04 as a height measurement can perform a success percentage of 96.95% and Loadcell Sensor as a weight measurement can perform the percentage of success is 98.97%, while in measuring Body Mass Index (BMI) can do a success percentage of 90.84%, the measuring instrument can also emit sound in the form of body condition in accordance with the measurement results obtained by the microcontroller with a success percentage of the sound output of 100% but has an average percentage of voice output delay variations of 2.1 seconds.

A note on invertibility and relative degree of MIMO LTI systems

The property of system invertibility is important both from a theoretical standpoint and an important consideration in left and right inversion problems that deal with input estimation and tracking control respectively. Nuances associated with the notion of relative degree in multi-input, multi-output (MIMO) systems on account of input–output delays pose challenges in system inversion problems and are more acute in the case of non-square systems. In this note, using the LTI discrete-time MIMO systems framework, we review existing notions of relative degree and develop new definitions and generalizations for relative degree to help address some of the gaps in system inversion problems. In doing so, we also show through simple but elegant results that existence of well-defined relative degree for an LTI MIMO system implies its invertibility. Furthermore, we also highlight the utility of these ideas in practical tracking control and input estimation situations and problems.

Development of a Piezoelectric Actuated Tactile Stimulation Device for Population Receptive Field Mapping in Human Somatosensory Cortex With fMRI.

Multichannel tactile stimulation devices is need to investigate human finger population receptive field (pRF) characteristics in the primary somatosensory cortex during functional magnetic resonance imaging (fMRI). To accurately characterize right-hand somatosensory representation based on the Bayesian pRF model. Prospective. A water phantom and six healthy participants (four males, mean 23.8 years old). T1-weighted magnetization-prepared rapid gradient-echo, T2*-weighted echo planar imaging at 3T. The piezoelectric actuated tactile stimulation device consisted of execution unit and control unit. The output performance of the device was measured by a laser displacement sensor. The effect of the device on images' signal-to-noise ratio (SNR) was measured by phantom experiments. The activation representation arrangement order, relative volumes, and receptive field size of the right hand were assessed during the along-digits and cross-digits paradigms. The normality of the data was tested by the Shapiro-Wilk method. A paired-sample t test was performed to test pRF characteristics for all digit pairings. The significance level was set to P=0.05 (false discovery rate [FDR] correct). Percussive stimulation provided by the piezoelectric actuated tactile stimulator had a stable displacement (2.64 mm) over a wide range of vibration frequencies (0-30 Hz). The output delay of the device was 1millisecond. The device did not affect the image's SNR (without the device: SNR=138.24 ± 7.87, temporal SNR [TSNR]=440.03 ± 52.08. With the device: SNR=138.06 ± 8.44, TSNR=438.52 ± 56.38. PSNR =0.88, PTSNR =0.46). Representations of right-hand fingers showed the same arrangement order in both experiments (D1-D5 arranged along the central sulcus). However, the relative volumes of D3 showed significant differences in S1 (P=0.003). Among four subareas, the relative volumes of D3 were significantly different in area 1 (P=0.047). This developed stimulator, through experimental verification, could play a role in pRF mapping exploration. 2 TECHNICAL EFFICACY STAGE: 1.

Event-triggered predictive control of nonlinear stochastic systems with output delay

In this paper, we focus on the stabilization of nonlinear stochastic systems with output delay. Based on the predictive scheme and event-triggering mechanism (ETM), a novel event-triggered predictive control is proposed to exponentially stabilize such stochastic systems. Moreover, this novel control law allows non-uniform sampled measurements and large delays involved in the output. Simultaneously, the control input error induced by ETM is considered and a positive lower bound on the inter-event times is obtained. Finally, an illustrative example is given to demonstrate the obtained results.

Delay Analysis and the Control of Electro-Hydrostatic Actuators

The electro-hydrostatic actuator (EHA) has a high energy density and a compact structure so it is widely used in all/more electric aircraft. To gain energy-saving capability, the hydraulic lock can be applied in the EHA system, which can overcome the change of load after the position control is complete, reducing the motor’s need to work continuously. Due to the use of a hydraulic lock in the EHA system, there is a more significant position output delay compared with the EHA system. The delay would lead to a dynamic response error. Therefore, an electro-hydrostatic actuator with a bidirectional hydraulic lock (BHL-EHA) model is established that can reflect the position output delay and it can be used to analyze its influence factors. According to the analysis, the factors affecting the delay are pump speed, external load, hydraulic lock cracking pressure, friction load, pump displacement, fluid volume of the system, and effective bulk modulus; thus, an equation that can be used to calculate the delay is proposed. At the same time, the experimental system of the BHL-EHA system is established, and the parameters of the experimental facility are completely consistent with the simulation model. Finally, a delay compensation control method is proposed, and the control time parameter t0 is calculated based on the equation proposed above. The results of the simulation and the experiment show that the method can compensate for the delay caused by the hydraulic lock. Combined with a feedforward control, the method can dismiss the dynamic response error of 0.6 Hz sinusoidal tracking characteristics.

Output Feedback Stabilization for a Wave-ODE Cascade System with the Time-Varying Input and Output Delay

Output Feedback Stabilization for a Wave-ODE Cascade System with the Time-Varying Input and Output Delay

MTPA control of permanent magnet synchronous motor based on dual-vector model predictive control.

The vector control of the permanent magnet synchronous motor (PMSM) is affected by cross-coupling, output delay, parameter mismatch, and other factors; thus, resulting in its poor steady-state and insufficient dynamic performance. To address these problems, the design proposed in this study adopts a model predictive current control strategy. In the traditional model predictive control, the absolute value of the difference between the predicted output current of the inverter and the reference current is used as the cost function instead of the minimum value of the valence function, i.e., the optimal solution of the system, and the best switching state is outputted. The design proposed in this study adopts the dual-vector model to predict the current control. Firstly, the reference voltage vector was predicted on basis of the deadbeat idea, which reduced the calculation burden of processor. Next, in order to further improve the stability of the system, a two-vectors duty cycle calculation method was introduced. Then, simplifies the selection range of the two voltage vectors. While ensuring the accuracy of the voltage vector, the control is reduced. Reduce the amount of calculation in the system, thereby improving its robustness. Finally, based on the principle of current vector tracking error minimization, the duration of the selected voltage vector was determined. Last but not the least, the control strategy is applied to the MTPA control to increase the operating efficiency of the control motor. The improved control strategy can effectively reduce the torque ripple and improve the dynamic and steady-state performance of the system. Simulation results verify the feasibility and effectiveness of the proposed control algorithm.

Adaptive neural smooth finite-time controller for large-scale stochastic nonlinear state-constrained systems with feasibility removal and time delays

This paper studies the adaptive smooth finite-time neural controller design for large-scale stochastic nonlinear systems subject to command filter and time-delay interactions. The main features are (1) the communication interconnection has the output delay between subsystems; (2) the smooth finite time strategy is given for stochastic disturbances; (3) all states are confined in the constrained space without feasibility conditions. First, the state time-delay interactions are tackled by the appropriate establishment of Lyapunov–Krasovskii functionals. Second, for full-state constraints, state-related mappings are employed to remove the feasibility. Then, by constructing the switching virtual control signals, the smooth fast finite-time feature is attached to the controller. Finally, based on finite-time stability theory in probability, command filter, and backstepping technique, the smooth fast finite-time neural controller is constructed to make that all system states converge in finite time, all closed-loop variables are bounded in probability, and full-state constraints are satisfied. Simulation results are provided to test the correctness of the method.

Output Feedback Synchronization for Networks of Hyperbolic PDE–ODE Systems

This paper considers the output feedback design for the leader-follower synchronization of a network of linear hyperbolic PDE–ODE systems and in particular ODE agents subject to distinct input and output delays. For a communication restricted by a directed graph, a cooperative state feedback is designed using a local backstepping stabilization of the PDE subsystem and a cooperative decoupling transformation. With this, the synchronization problem is traced back to a simultaneous stabilization of the boundary ODEs without introducing additional dynamics in the networked controller. For general PDE–ODE agents an observer using absolute measurements is proposed, while for ODE agents with delays the observer only requires relative measurements. The results of this paper are demonstrated for the output feedback synchronization of ODE agents with distinct input and output delays.

Control of Large-Scale Delayed Networks: DDEs, DDFs and PIEs

Delay-Differential Equations (DDEs) are the most common representation for systems with delay. However, the DDE representation has limitations. In network models with delay, the delayed channels are typically low-dimensional and accounting for this heterogeneity is challenging in the DDE framework. In addition, DDEs cannot be used to model difference equations. In this paper, we examine alternative representations for networked systems with delay and provide formulae for conversion between representations. First, we examine the Differential-Difference (DDF) formulation which allows us to represent the low-dimensional nature of delayed information. Next, we consider the coupled ODE-PDE framework and extend this to the recently developed Partial-Integral Equation (PIE) representation. The PIE framework has the advantage that it allows the H∞-optimal estimation and control problems to be solved efficiently using the recently developed software package PIETOOLS. In each case, we consider a very general class of networks, specifically accounting for four sources of delay - state delay, input delay, output delay, and process delay. Finally, we use a scalable network model of temperature control to show that the use of the DDF/PIE formulation allows for optimal control of a network with 40 users, 80 states, 40 delays, 40 inputs, and 40 disturbances.

State Observation of Affine-in-the-States Systems with Unknown Time-Varying Parameters and Output Delay

In this paper we address the problem of adaptive state observation of affine-in-the-states time-varying systems with delayed measurements and unknown parameters. The development of the results proposed in the [Bobtsov et al. 2021a] and in the [Bobtsov et al. 2021c] is considered. The case with known parameters has been studied by many researchers—see [Sanz et al. 2019, Bobtsov et al. 2021b] and references therein—where, similarly to the approach adopted here, the system is treated as a linear time-varying system. We show that the parameter estimation-based observer (PEBO) design proposed in [Ortega et al. 2015, 2021] provides a very simple solution for the unknown parameter case. Moreover, when PEBO is combined with the dynamic regressor extension and mixing (DREM) estimation technique [Aranovskiy et al. 2016, Ortega et al. 2019], the estimated state converges in fixed-time with extremely weak excitation assumptions.

TDS-CONTROL: a MATLAB package for the analysis and controller-design of time-delay systems*

This paper presents TDS-CONTROL, a MATLAB package for the analysis and design of controllers for linear time-invariant systems with discrete delays. The code is based on a state-space representation of such systems in terms of delay-differential algebraic equations with input, output, and state delays. As such, a broad class of (interconnected) systems can be considered, including neutral systems. The controller design algorithms are based on optimizing a certain objective function, such as the spectral abscissa, the H-infinity norm, or the pseudo-spectral abscissa, with respect to the controller parameters. For example, to design a stabilizing controller the spectral abscissa, i.e., the real part of the right-most characteristic root, is minimized. As a strictly negative spectral abscissa is a necessary and sufficient condition for stability, the presented design method is not conservative and a stabilizing controller can be computed whenever it exits. This comes however at the cost of having to solve a non-smooth, non-convex optimization problem. The class of considered controllers consists of static and dynamic output-feedback controllers. By allowing to fix certain entries in the controller matrices, it is also possible to design structured controllers such as decentralized, overlapping and PID controllers. Finally, as a wide-range of delay systems can be considered, the software package takes the sensitivity of certain quantities, such as the spectral abscissa and the H-infinity norm, with respect to infinitesimal delay perturbations explicitly into account.

Predictor-based periodic event-triggered control for nonlinear uncertain systems with input delay

In this paper we investigate the problem of predictor-based periodic event-triggered control for a class of nonlinear uncertain systems subject to input delay. When only sampled-data output is available, a novel predictor-based continuous-discrete observer is first designed to estimate system state, and an event-triggered controller is second proposed to globally exponentially stabilize the nonlinear uncertain system. Under the proposed control method, the effects of input delay and sampling of output can be considerably compensated thanks to prediction technique. As a byproduct, the Zeno behavior is avoided in nature since the proposed event-triggering mechanism is detected in the form of discrete-time. Some sufficient stability conditions on maximum allowable sampling period and input delay are presented by using feedback domination technique and small-gain argument.

Characterisation of analogue front end and time walk in CMOS active pixel sensor

In this work we investigated a method to determine time walk in an active silicon pixel sensor prototype using Edge-TCT with infrared laser charge injection. Samples were investigated before and after neutron irradiation to 5· 10^14n_ eq/cm^2. Threshold, noise and calibration of the analogue front end were determined with external charge injection. A spatially sensitive measurement of collected charge and time walk was carried out with Edge-TCT, showing a uniform charge collection and output delay in pixel centre. On pixel edges charge sharing was observed due to finite beam width resulting in smaller signals and larger output delay. Time walk below 25 ns was observed for charge above 2000 e^- at a threshold above the noise level. Time walk measurement with external charge injection yielded identical results.

LMI-Based H∞ Controller of Vehicle Roll Stability Control Systems with Input and Output Delays.

Many of the current research works are focused on the development of different control systems for commercial vehicles in order to reduce the incidence of risky driving situations, while also improving stability and comfort. Some works are focused on developing low-cost embedded systems with enough accuracy, reliability, and processing time. Previous research works have analyzed the integration of low-cost sensors in vehicles. These works demonstrated the feasibility of using these systems, although they indicate that this type of low-cost kit could present relevant delays and noise that must be compensated to improve the performance of the device. For this purpose, it is necessary design controllers for systems with input and output delays. The novelty of this work is the development of an LMI-Based H output-feedback controller that takes into account the effect of delays in the network, both on the sensor side and the actuator side, on RSC (Roll Stability Control) systems. The controller is based on an active suspension with input and output delays, where the anti-roll moment is used as a control input and the roll rate as measured data, both with delays. This controller was compared with a controller system with a no-delay consideration that was experiencing similar delays. The comparison was made through simulation tests with a validated vehicle on the TruckSim® software.

Nonlinear Control System for Non-Affine Undefined Plants with Output Delays

The article deals with the problem of synthesis of the control algorithms for combined nonlinear control system for one class of single-channel non-affine priory uncertain plants with state delay in the presence of permanent bounded external noises and at measuring only the plant’s output signal. 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 operation quality of the obtained system at different values of the plant relative order and its parameters is shown. The results obtained in article may be useful for construction the control systems for different dynamic plants which contains input nonlinearities and state delays.