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This work studies the ${H}_{\infty }$ -based minimal energy control with a preset convergence rate (PCR) problem for a class of disturbed linear time-invariant continuous-time systems with matched external disturbance. This problem aims to design an optimal controller so that the energy of the control input satisfies a predetermined requirement. Moreover, the closed-loop system asymptotic stability with PCR is ensured simultaneously. To deal with this problem, a modified game algebraic Riccati equation (MGARE) is proposed, which is different from the game algebraic Riccati equation in the traditional ${H}_{\infty } $ control problem due to the state cost being lost. Therefore, a unique positive-definite solution of the MGARE is theoretically analyzed with its existing conditions. In addition, based on this formulation, a novel approach is proposed to solve the actuator magnitude saturation problem with the system dynamics being exactly known. To relax the requirement of the knowledge of system dynamics, a model-free policy iteration approach is proposed to compute the solution of this problem. Finally, the effectiveness of the proposed approaches is verified through two simulation examples. [ABSTRACT FROM AUTHOR]

Quasi-two-dimensional (quasi-2D) perov- skites possess the preponderances of large exciton binding energy and quantum confinement effects compared with three-dimensional (3D) perovskites. The unique properties of quasi-2D perovskite have attracted extensive attention in the field of optoelectronic devices, especially in the light emitting diode (LED) direction. However, the adverse effects between the perovskite emission layer and the popularly used hole transport layer (HTL) Poly(3,4-ethylenedioxythiophene):poly (styrene sulfonate) (PEDOT:PSS) have degrade the device performance, such as large energy level barrier and exciton quenching. Here we demonstrated high performance of LED with enhanced brightness and efficiency by modifying the PEDOT:PSS with NdBr3, which not only decreases exciton quenching, but also decreases HOMO level of the PEDOT:PSS, thereby improving the charge balance. The final performance of the perovskite light-emitting diode (PeLED) device was obtained with a maximum luminance of 18684 cd m−2, a maximum current efficiency (CE) of 48.4 cd A−1 and an external quantum efficiency (EQE) of up to 15.5% when using NdBr3 modified PEDOT:PSS. [ABSTRACT FROM AUTHOR]

This article designs performance adjustable event- and self-triggered policies for nonlinear multiagent systems with controller output fluctuations. In the provided event-triggered mechanism, a performance adjustable function is introduced, which can freely adjust the system sampling frequencies and state convergence rates. In the proposed self-triggered policy, continuous measurement error monitoring and neighbors’ event listening are avoided, thereby further saving system sensor resources. Furthermore, under a unified framework, the controllers’ inherent nonlinearities and the influence of data quantization in digital communication networks are studied. In comparison with the previous event-triggered sampling schemes, the developed policies do not only study the multiagent coordinated control in terms of system sampling performance and state convergence performance but are also suitable for the scenarios with controller output fluctuations. Numerical simulation results verify the effectiveness and superiority of the proposed policies. [ABSTRACT FROM AUTHOR]

This article presents integral-type edge event- and self-triggered policies for Lipschitz nonlinear multiagent systems, in which only edge states are employed by all controllers. An integral-type triggering function is designed to determine event instants, and the considered system can achieve Zeno-free triggering. An integral-type edge self-triggered policy is then designed to avoid sensors’ continuous measurements. Compared to traditional event-triggered schemes, the proposed strategies have relaxed triggering conditions and lowered the event frequencies. Also, the proposed edge self-triggered algorithm can avoid the requirement for continuous measurement error monitoring. Numerical simulations are given to demonstrate the effectiveness of the theoretical conclusions. [ABSTRACT FROM AUTHOR]

This paper introduces a novel consensus-based labeled multi-Bernoulli (LMB) filter to tackle multi-target tracking (MTT) in a communication resource-sensitive distributed sensor network (DSN). Although consensus-based approaches provide effective tools for distributed fusion and MTT, the requirement of iterative communication makes it impractical in resource limited situations. To deal with this issue, two event-triggered strategies are proposed and incorporated into the consensus-based LMB. Focusing on the information discrepancy between the local multi-target probability density function (PDF) and the time prediction of the latest broadcast one, the integral-triggering strategy (ITS) is introduced. Furthermore, by proving that the information discrepancy (Kullback-Leibler divergence) between two LMB densities with the same label space can be decomposed into the sum of the information discrepancy of each LMB component pair (LMB components with the same label), the separated-triggering strategy (STS) is proposed. The performance of the proposed algorithms is demonstrated in a distributed multi-target tracking scenario via numerical simulations. [ABSTRACT FROM AUTHOR]

This brief studies the synchronization problem of nonlinear multi-agent systems (MASs) with the quadratic condition (QUAD-condition) via prescribed performance control (PPC), where a novel performance function is employed that can configure the convergence rate arbitrarily. With the designed protocol, all relative states’ evolution is within the preset performance envelopes, and the system achieves state synchronization asymptotically. In comparison with the existing studies, we first investigate the coordinated control of QUAD nonlinear MASs with prescribed trajectory behaviors. Moreover, the convergence rate of the proposed performance constraint function can be selected arbitrarily, which has better versatility. Simulations on coupled chaotic circuit networks verify the theoretical results. [ABSTRACT FROM AUTHOR]

Path planning and formation control are both challenging and critical issues in robotics, which involve computing an optimal path from the initial position to target while keeping the desired formation. This brief studies the path planning and formation control problem for multiple unmanned aerial vehicles (multi-UAVs) in 3-D constrained space. Considering the local minimum of artificial potential function (APF), an effective improved artificial potential function (IAPF) based path planning approach is proposed for the multi-UAV systems. By introducing a rotating potential field, the UAVs can escape from the common local minimum and oscillations efficiently. Afterwards, by using the leader-follower model, a formation controller based on potential function method is developed to ensure that the follower UAVs keep the desired angles and distances with the leader, and a Lyapunov function is designed to analyze the closed-system stability. Finally, simulation studies under different environmental constraints confirm the efficiency of the proposed approaches in addressing the path planning and formation control issues in 3-D space. [ABSTRACT FROM AUTHOR]

This brief studies the simultaneous estimation of states and uncertainties in general continuous-time systems. In particular, we present a novel time-varying learning intensity (TLI) learning observer (LO). It has the advantage of inheriting the valuable properties of conventional LOs with a simple structure, i.e., the uncertainty estimation is achieved using simply one algebraic equation with low computational costs. The foremost difference in comparison with conventional LOs is the utilization of the TLI approach, which attenuates the overshooting response in the case of large estimation errors and obtains decent performance improvement. Simulations for constant and time-varying signals demonstrate a notable performance boost of TLI-LO. [ABSTRACT FROM AUTHOR]

InP quantum dots (QDs)-based light-emitting diodes (QLEDs) are considered as one of the most promising candidates for environmentally cadmium (Cd)-free electroluminescence devices. However, the performance of InP QLEDs still lags far behind that of Cd-containing QLEDs, which limits their practical applications in next-generation displays and lighting. Here, we report an all-solution processed green InP QLED, which is enabled by an electron transport layer (ETL) of In-doped ZnO (IZO) nanoparticles (NPs). The ETL of IZO NPs can not only suppress the exciton quenching of InP QDs emitting layer due to the reduced defect states, but also improve the charge balance by partially blocking the injection of electrons, and thus the device performance. The optimized InP QLED exhibits a maximum external quantum efficiency (EQE) of 5.42% corresponding to a current efficiency (CE) of 21.22 cd A−1, which is three times higher than that of the control device based on ZnO ETL, respectively. Our work suggests that IZO NPs can function as a good ETL material in QLEDs and other optoelectronic devices. [ABSTRACT FROM AUTHOR]

Earth geomagnetic field provides very important information for autonomous navigation. However, in practice, magnetometer measurements are easily distorted by outer disturbances, as shown in the right diagram. In a recent study, the real-time magnetometer disturbance estimation problem has been solved via a constrained nonlinear programming for better underwater navigation accuracy. However, the employed interior-point optimizer will require considerable computational resources and cannot always guarantee optimality during optimization updates. This paper further investigates this problem and refines the solution by introducing the trust-region method. The challenge of the designed approach mainly falls into finding out the feasible regions of the possible solutions. Geometric analysis and algebraic elimination methods are taken into account to give globally optimal solutions to the trust-region solver. Experimentations are conducted to verify the correctness of the proposed method. Moreover, it is also confirmed that the trust-region technique can continuously and accurately propagate so that high-frequency dynamic magnetic disturbances can be efficiently estimated. [ABSTRACT FROM AUTHOR]

This brief investigates event-triggered control for spacecraft attitude stabilization under the influence of actuator output nonlinearities. Under a designed event-triggered policy, the influences of actuators’ inherent nonlinearity and network quantized transmission are evaluated under a unified framework. Compared with the previous results, the influences of data transmission and actuators’ inherent nonlinearities are uniformly described as the actuator output nonlinearities, and the event-triggered policy reduces the effects of constants commonly introduced into triggering conditions on the final state convergence regions and achieves Zeno-free triggering. Simulations verify theoretical results. [ABSTRACT FROM AUTHOR]

This brief investigates the problem of trajectory tracking control for dynamic positioning vessels under unknown and time-varying sea loads. A novel event-based prescribed performance control (PPC) scheme is proposed to address this problem. Firstly, an integral disturbance observer (IDO) is introduced to estimate the sea loads, and a new-type performance function (PF), which has advantages of flexible shape and appointed-time convergence, is proposed to form the funnel envelops for the trajectory tracking errors. Subsequently, by employing the IDO and the new-type PF, a dynamic event-triggered control policy is designed in the PPC framework to achieve the assigned trajectory tracking mission in an appointed-time with guaranteed performance bounds and less operating frequency of the actuator. The salient feature of the derived controller is that it can achieve a trade-off between the tracking performance and actuators’ operating frequency in a well-balanced way, which is of great importance for practical engineering applications. Finally, simulation results are given to show the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

A novel integrated quantized- and event-based control (IQEC) scheme for intra-spacecraft with communication-saving ability is proposed to address the attitude tracking control problem. The IQEC scheme reduces the control updating frequency and the data length per transmission based on the event-based control and quantized communication techniques, thus reducing the system communication occupation. By suitable control system configuration, the purpose of communication-saving is achieved, from sensors to the computing unit and from the computing unit to actuators. The proposed algorithm’s effectiveness is verified via numerical simulation that uses a general actuator model with second-order dynamics. [ABSTRACT FROM AUTHOR]

Hand-eye calibration (HEC) is a kernel technique guaranteeing precision industrial visual servoing and robotic grasping. Extensive studies have been conducted to various closed-form and iterative solutions to HEC problems using different pose parameterizations. However, these approaches are either sensitive to input noise or time-consuming for implementation. This article provides a new perspective on a deterministic solution to two major branches of HEC problems of forms AX = XB and AX = YB. We use symbolic methods to derive a globally optimal solution. Different from representatives based on optimization, this method is not only the most accurate against others but also with repeatability of 100%. Experiments via industrial robotic manipulator verify the superiority of the proposed algorithm. [ABSTRACT FROM AUTHOR]

In many pose estimation problems, rotation matrices can not always be estimated subject to all nonlinear rigidity constraints. Therefore, engineers tend to obtain the nearest rotation matrix of an improper one, which is called the rotation orthonormalization problem. In this brief, we show a circuit synthesis of such problem by using only simple algebraic components. We give theoretical convergence analysis of the designed circuit. By using the proposed circuit, rotation orthonormalization can be easily performed without the need of previous sophisticated processes like singular value decomposition (SVD) and eigen-decomposition (EIG). Experiments of the developed method’s characteristics are conducted. The circuitized scheme has also been implemented on an FPGA platform. [ABSTRACT FROM AUTHOR]

For visually aided industrial robots, the transformation between the mounted visual information system and the end-effector must be calibrated prior to the practical use. However, during the data acquisition stage, measurement uncertainties will lead to inevitable mismatched data. This article proposes a novel correspondence matching method for the hand-eye calibration system of the type $\boldsymbol {AX} = \boldsymbol {XB}$. The correspondence matching refers to the problem of finding out the well-matched $\boldsymbol {A}$ and $\boldsymbol {B}$ and the relative time delay between them, from a series of measurements. A neat Lie algebra formulation has been obtained to cast the original problem into a high-dimensional point-cloud registration problem. This solution allows for the simultaneous solution of the hand-eye calibration, correspondence matching, and time-delay estimation as well as the uncertainty description of the obtained results. Synthetic simulations verify the correctness of the proposed method. Experimental studies have also confirmed its practical feasibility on an automatic welding platform. [ABSTRACT FROM AUTHOR]