Tracking Deviation Research Articles

Fuzzy adaptive finite-time output feedback control of stochastic nonlinear systems

An adaptive finite-time approach to the feedback control of stochastic nonlinear systems is presented. The fuzzy logic system (FLS) and a state observer are used to estimate the uncertain function and unmeasured state of the controlled system, respectively. A dynamic surface control (DSC) scheme is employed to deal with the “computational explosion” problem, which is inherent in traditional backstepping methods since the repetitive calculation of the derivatives of virtual control signals is avoided. A new output feedback controller is developed to guarantee that all the signals of the controlled system are bounded within a finite time range and the tracking deviation can converge to an arbitrarily small residual set within finite time. Simulations confirm the analytical and theoretical results of the presented algorithm.

Impact of assimilation of SCATSAT-1 data on coupled ocean-atmospheric simulations of tropical cyclones over Bay of Bengal

This study examines the impact of assimilation of the surface winds obtained from SCATterometer SATellite-1 (SCATSAT-1) in predicting the tropical cyclones over the Bay of Bengal using a coupled ocean-atmospheric model. Three sets of numerical experiments are conducted for six cyclones during post-monsoon (VARDAH, GAJA, PHETHAI) and pre-monsoon cyclones (MORA, FANI, AMPHAN). The first experiment, ‘CONTROL’, is conducted with the Weather Research and Forecasting - Ocean Mixed Layer (WRF-OML) model initialized using Global Forecasting System analysis and ocean initial conditions obtained from the HYbrid Coordinated Ocean Model (HYCOM) model. The second experiment, ‘PREPBUFR’, is conducted by assimilating the National Center for Environmental Prediction (NCEP) prepared BUFR observations with the WRF-OML model and three-dimensional variational assimilation method. Further, the 'SCATSAT' experiment is conducted as PREPBUFR, but additionally, the SCATSAT-1 surface wind vectors are assimilated. Our results of the simulated tracks from three experiments suggest that CONTROL and PREPBUFR simulations exhibit faster translation speed and more track deviations than the India Meteorological Department (IMD) observations. The realistic representation of low-level cyclonic vortex through the assimilation of SCATSAT-1 winds seems to produce positive feedback to both track and intensity, producing a significant improvement in predicting intensity and marginal enhancement on simulation of track and translation speed. The assimilation of winds further improved the representation of different life cycles of the storms as seen in IMD. The analysis of air-sea parameters, in terms of mixed layer deepening, sea surface temperatures, and air-sea flux exchanges, suggests that the response of air-sea feedback is strong in SCATSAT compared to PREPBUFR and CONTROL. Overall, the assimilation of SCATSAT surface winds improved the WRF-OML performance on the prediction of track and intensity, upper ocean response, primary and secondary circulations of tropical cyclones, and the rainfall distributions.

Tracking deviation correction control for landing taxiing of amphibious unmanned aerial vehicles

Air cushion landing system (ACLS) can help airplane realize amphibious take-off and landing. Even so, vehicle with the ACLS is more susceptible to uncertainties such as crosswind, unmolded dynamics and high nonlinearities than other take-off/landing methods, resulting in difficulty escalation for the tracking deviation correction (TDC) control. In this paper, to deal with the TDC problem for the airplane, a disturbance attenuation predictive control scheme is proposed. To enhance system robustness, a disturbance observer (DO) is designed to attenuate uncertainties through an online feedback compensation way. To degrade the influences such as input surging/saturation and large overshoot induced by sudden occurrence of uncertainties, a type of predictive controller considering tracking error and input power is developed. Contrast simulations are conducted to show the superiorities of the proposed control scheme.

Aircraft Track Anomaly Detection Based on MOD-Bi-LSTM

In order to ensure flight safety and eliminate hidden dangers, it is very important to detect aircraft track anomalies, which include track deviations and track outliers. Many existing track anomaly detection methods cannot make full use of multidimensional information of the relevant track. Based on this problem, an aircraft track anomaly detection method based on the combination of the Multidimensional Outlier Descriptor (MOD) and the Bi-directional Long-Short Time Memory network (Bi-LSTM) is proposed in this paper. Firstly, track deviation detection is transformed into the track density classification problem, and then a multidimensional outlier descriptor is designed to detect track deviation. Secondly, track outliers detection is transformed into a prediction problem, and then a Bi-LSTM model is designed to detect track outliers. Experimental results based on real aircraft track data indicate that the accuracy of the proposed method is 96% and the recall rate is 97.36%. It can detect both track deviation and track outliers effectively.

Design and Test of Auxiliary Steering System of High Clearance Sprayer Chassis Based on Self-steering Structure

A hydraulic assisted steering method was proposed to solve the problem of steering instability caused by insufficient reverse resistance moment of wheel hub motor in four-wheel independently electrically driven high clearance sprayer. Firstly, the principle of steering chassis structure of four-wheel independently electrically driven high clearance sprayer is briefly introduced. On this basis, hydraulic auxiliary steering system is designed. Then a simplified 2-DOF vehicle steering model is established to analyze the Angle control of the auxiliary steering system. Finally, simulation and road surface test are carried out respectively to verify the performance of steering and auxiliary steering coordination control. Under the working conditions of the steering system alone and the steering system and the auxiliary steering system together, the four-wheel electric drive sprayer carried out the obstacle crossing test and the downslope test with the slope of 15° respectively at the speed of 1 m/s on the smooth road surface. The test results show that in the downhill test, the maximum tracking deviation of the steering system alone is 6.1°, the maximum tracking deviation of the steering and auxiliary steering coordination is 0.9°, the maximum tracking deviation of the steering system alone is 12.0°, and the maximum tracking deviation of the steering and auxiliary steering coordination is 1.2° in the obstacle breaking test. The test results verify the feasibility and stability of the hydraulic steering system proposed in this paper. The system has good test performance and can meet the practical requirements.

Iterative Gradient Descent-Based Finite Control Set Predictive Current Control With Least-Squares Optimized Duty Cycles

Finite Control Set Predictive Current Control (FCS-PCC) is widely recognized as a competitive control strategy in the field of electrical drives, due to its superiority of fast dynamic response and low switching frequency. However, FCS-PCC is penalized by its inherent drawback that the discrete nature of switching states leads to relatively high torque and current deviations. In this paper, an iterative gradient descent method combined with least squares optimized duty cycles is presented to improve the steady-state performance of FCS-PCC. Unlike the cost function optimization in the conventional FCS-PCC, the quadratic programming problem is solved from a geometric perspective, by obtaining the gradient descent which minimizes the tracking deviation in the fastest manner. To synthesize the gradient descent, the optimal stator current derivatives in the current and previous iteration are employed, and their duty cycles are determined by the least squares method. The abovementioned procedures are iteratively repeated in the dichotomy-based periods. The experimental performance of the proposed gradient descent based FCS-PCC is verified at a 8 kHz sampling frequency, which is compared with that of conventional and dichotomy-based FCS-PCC. It is validated that the proposed algorithm outperforms the conventional and dichotomy-based FCS-PCC at both the steady-state and transient state.

Bi-criteria Aircraft Trajectory Optimization in Implementing the Area Navigation Concept

To solve a problem of bi-criteria optimization of an aircraft flight trajectory using the data of satellite navigation systems, the authors suggest an approach based on the game theory methods. The target was set to organize trajectory control with two partial criteria of optimality (desired track deviation and position-fixing error) minimized simultaneously. It is shown that the minima of individual partial criteria are generally achieved with different control inputs and hence with different flight path parameters so there is a need to form an additional strategy for decision making in a bi-criteria optimization problem taking into account existing restrictions. Based on the multi-criteria optimization methods, an algorithm for aircraft trajectory control was synthesized. The comparative analysis of the research results shows that the synthesized algorithms of optimal control based on the suggested approach make it possible to find a compromise solution for a multi-criteria trajectory optimization problem in the area of global navigational satellite system augmentation. Proposals were drawn up to construct spatial programmed trajectories aiming to high-accuracy navigational sightings.

An Underwater Micro Cable-Driven Pan-Tilt Binocular Vision System With Spherical Refraction Calibration

To improve the operation performance of underwater robots, a novel micro cable-driven pan-tilt camera system is developed, which can play an important role in underwater environmental perception and visual measurement. The designed camera system encompasses three parts: a miniature mechanical structure, a real-time target tracking and location module, and an underwater spherical refraction calibration module. Originally, a cable-driven model is adopted to establish a micro and flexible pan-tilt structure, for which the corresponding active target tracking and location algorithms are proposed. More importantly, for eliminating the measurement error caused by the underwater spherical refraction, an advanced nondominated sorting genetic algorithm (NSGA-II)-based underwater calibration algorithm is presented with the aid of the comprehensive geometric spherical refraction model. By integrating the flexible pan-tilt camera and the proposed calibration algorithm, the performance of underwater environmental perception and visual measurement can be greatly improved. Finally, extensive experiments in air and underwater scenarios are conducted. According to the utilized evaluation index, the deviation of target tracking and underwater location errors can be maintained within 0.06 rad and 21 mm, respectively. The proposed vision system sheds light on precise perception and interaction tasks of underwater vehicles.

Roll Stability and Path Tracking Control Strategy Considering Driver in the Loop

A study pointed out that the delay time of the driver's nervous system has a significant effect on the roll stability of the vehicle. However, the existing researches on vehicle rollover prevention control rarely consider the influence of driver factors on vehicle roll stability. Aiming at this problem, a vehicle roll stability and path tracking control strategy considering driver in the loop is proposed to assist different types of drivers. It includes the supervisory decision layer and execution layer. The supervisory decision layer selects the corresponding control mode according to the driver's steering wheel angle change rate, path tracking deviation and vehicle roll stability information. The execution layer includes three modes: human-machine shared steering, active braking and integrated chassis control. The human-machine shared steering and active braking modes assist the driver to improve the roll stability and path tracking accuracy. The integrated chassis control mode is used for the automatic driving of vehicles under emergency conditions. Simulation results show that the proposed control strategy can effectively improve the vehicle roll stability and path tracking accuracy, and reduce the driver's operating burden.

Fuzzy Finite-Time Tracking Control for a Class of Nonaffine Nonlinear Systems With Unknown Dead Zones

This paper addresses the finite-time tracking control problem for a class of nonaffine nonlinear systems with unknown dead zones using an adaptive fuzzy control scheme. The unknown nonlinear functions of the system are approximated by the fuzzy logic systems and a finite-time stability theorem is used to construct the control signal. The novelty of the proposed control method is that the tracking system can reach the stable equilibrium within a finite period of time without the knowledge of the boundaries of the dead zone parameters. The simulation results show that the system is semi-global practical finite-time stable and the tracking deviation converges to a small neighborhood of zero in a finite period of time.

Dynamic photogrammetry applied to a real scale heliostat: Insights into the wind-induced behavior and effects on the optical performance

Wind loads may decrease a heliostat’s optical performance by affecting its shape and orientation. As small scale wind tunnel or numerical models cannot reflect a heliostat’s dynamic behavior entirely, in this study we investigated a real scale Stellio heliostat installed on the DLR heliostat testing platform where it was exposed to the natural wind. The wind-induced response was captured with a dynamic photogrammetry system that combines a high spatial and high temporal resolution. As its application to a heliostat is novel, the first focus of this paper is to validate the applied setup and the accuracy of measured displacements. The second focus is to discuss the wind-induced Stellio behavior. A method is presented which allows for separating the total wind-induced behavior into a tracking- and a slope-relevant part. Based on this separation, the wind-induced tracking deviation (0.44mradRMS) during the investigated measurement period (mean wind speed ≈4.8m/s, mean turbulence intensity ≈26%) reached a level of approximately one third of a heliostat’s typical total tracking deviation. Likewise, during the time step of largest deformations, the wind-induced slope deviation (0.75mradRMS) of the most affected facet reached a level of approximately one third of a Stellio facet’s total slope deviation. However, wind-induced slope deviations occurred only locally and temporally. Furthermore, wind-excited eigenfrequencies were revealed to have a negligible impact on both the tracking and slope deviation in case of the Stellio. Oscillations and deformations related to frequencies below the eigenfrequencies were rather found to have a predominant impact on the optical performance.

Coordinated control based path following of distributed drive autonomous electric vehicles with yaw-moment control

This research seeks to study the path following issue for distributed drive autonomous electric vehicles (DDAEV). In order to improve the tracking accuracy and vehicle stability, coordinated control of tracking deviation compensation and vehicle stability by yaw-moment is proposed. Based on the three degree-of-freedom vehicle model, model predictive control is used to calculate the steering angle of front wheels to control the vehicle along the reference path by autonomous steering. In this process, two sliding surfaces whose control targets are tracking deviation and yaw rate deviation are first set, then two sliding surfaces are combined into one coordinated sliding surface with weight coefficients considering the vehicle stability, and finally the yaw-moment is figured out and distributed with the constant torque requirement of the vehicle. Carsim co-simulation with Simulink and Hardware-in-the-Loop experiment are conducted, which shows that compared to autonomous steering control, coordinated control achieves better path following accuracy and vehicle stability for DDAEV under different driving conditions.

INCREASE OF OPERATING RELIABILITY OF THE TRAVEL WHEEL USING THE USE OF THE ELASTIC INSERTS

The aim of research is to substantiate the rational design of the travel wheel based on the determination of the dynamic forces arising from the movement of the freight carriage and the crane bridge. The research methodology is based on analytical methods for studying dynamic forces in the mechanism of movement of the cargo carriage of an overhead crane. The obtained solution of the three-mass dynamic scheme of the movement of the freight carriage. To verify the theoretical data obtained, an experiment was carried out on an overhead crane with a lifting capacity of 5 , span of 22.5 m, lifting height of 8 m, operating mode of 7 K. The study of the vibration state was carried out on the crane beam in the middle of the span, on the axis of the driven wheel of the crane trolley with an elastic insert and on the axis of the drive wheel of the crane trolley of a conventional design. Crane wheels are the fastest wearing parts of a crane. A decrease in their durability leads to an increase in repair costs and crane downtime. Therefore, increasing the durability of crane travel wheels is an urgent task of modern crane construction. All designs of travel wheels are quite rigid and do not perceive shocks and distortions arising from the deviation of the rail track from the recommended values and lead to significant wear of the flanges and rails. The analysis of the obtained solutions showed that when using a travel wheel with an elastic insert, the dynamic factors during the movement of the freight carriage decrease. Dependences are obtained for determining the dynamic forces arising from the movement of the travel crane wheel, taking into account the rigidity of the elastic ring, which is installed in the travel wheel. The analysis of the regularities of the formation of vibration signs at different points of the overhead crane structure is carried out. The proposed design and calculation method for a travel wheel with an elastic insert improves its operational reliability

Sliding mode control of an ozone generator based on dual AC/DC/AC power converters

The aim of this study was to design a first-order sliding mode controller for dual AC/DC/AC power converters to regulate the production of a corona discharge ozone generator. The design is presented in the two following parts: (a) The first part regulates a three-branch (phase) AC/DC converter to control the DC intermedium voltage that is required to produce the desired ozone concentration, while (b) the second part regulates a one-phase DC/AC power conversion circuit that regulates amplitude of the AC voltage that must be injected into the reaction chamber of the ozone generator. For the first section, the controller regulates the switching sequence yielding the control of the input currents, which defines the amplitude of the DC voltage. In the second, the switching control regulates the amplitude of the expected output AC signal, which depends on the obtained DC voltage from the AC/DC section. This structure represents a novel form to adjust the functioning of the AC/DC/AC power device, which has not been used before in the context of ozone production. Lyapunov’s second method was the main tool for confirming the existence of an asymptotical equilibrium state point for the trajectory tracking deviation for both sections of the power converter. The voltage amplitude was tested on a previously validated mathematical model of a corona-effect ozone generator performance. Several numerical evaluations illustrated the efficient performance of the suggested discontinuous controller and considering the proposed switching sequence that realizes the control action. The proposed controller was contrasted with a usual proportional/integral/derivative (extended state) design, which is a common technique to regulate the ozone generation system.

Design and performance analysis of an annular fresnel solar concentrator

In this paper, an annular Fresnel solar concentrator (AFSC) is proposed. This novel concentrator was incorporated with a series of annular mirrors, and its performance was simulated using MATLAB software. The influences of different structures were also simulated. The tracking deviation, device deviation, and comprehensive deviation were analysed using different deviation angles. The results demonstrated that this concentrator could simply adjust the concentrating ratio, which reached 300 when the maximum concentrator height was 0.78 m and the maximum diameter was only 1.72 m. Non-linear changes in the performance of the annular Fresnel reflector occurred when the structure size increased linearly. Further, the radiation distribution and performance of the annular Fresnel reflector were found with different deviations. When the tracking deviation angle was 0.5°, the receiving rate was 98.37%. This new AFSC has excellent concentrated solar power (CSP) application prospects.

Decadal behaviors of tropical storm tracks in the North West Pacific Ocean

Quantitative analysis on the shape of 959 tropical storm (TS) tracks in the North West Pacific (NWP) basin was carried out over the period from 1977 to 2016 by using International Best Track Archive for Climate Stewardship (IBTrACS) provided by National Oceanic and Atmospheric Administration (NOAA) based on an established track sinuosity metric. Track sinuosity is a measure of deviation of a storm track from its straight–line path between the cyclogenesis and cyclolysis locations. More sinuosity in the storms' tracks makes it rather challenging for the atmospheric models to accurately assess the storms' respective locations on the map and potentially causes higher damages due to lack of precise information about their movement. Statistical analysis was carried out on spatial and temporal trends (monthly to decadal) of the TS track shape and the obtained results were mapped based on sinuosity categories within a GIS environment. The sinuosity distribution results are normalized using a cube–root transformation function to reduce skewness and obtain sinuosity index (SI). Distinct enhancement of TS sinuosity was noticed from the months July to October (JASO). It is also detected that early months of TS season like June–August have dominance of more predictable straighter storm tracks over sinuous kind of tracks, and vice-versa in the case of late months of season like September–October. It is also evident that there is a one- to three-year cyclic pattern of changing sinuosity over the NWP basin. The 1987–1996 decade had the maximum dominance of sinuous tracks in comparison to the other three decades. Significant longitudinal eastward shift (from 110°–140° E to 130°–160° E) in majority of cyclogenesis locations is observed as sinuosity in storm track increases from straight to sinuous patterns. Similar shift for latitudinal track was not found. Finally, we investigate the sinuosity based on the warm/cold phase of the ENSO. Warm phase of ENSO is found to be associated with a greater number of TS with higher SI values in the NWP basin. These TS during warm phase mostly originate in the eastern part of the basin where a vast open area of warm sea surface temperature encourages their formation and intensification. Lastly, the study found a moderate positive relationship between SI and TS' longevity and distance coverage, which are crucial information for disaster risk assessment, mitigation and preparedness.

Non-uniform sizing of PV cells in the dense-array module to match the non-uniform illumination in dish-type CPV systems

Abstract To reduce the efficiency reduction caused by non-uniformity of illumination, a dense-array module with non-uniform sizing of photovoltaic (PV) cells is proposed for dish-type concentrating PV systems. The non-uniform-sized dense-array module has been designed and analyzed theoretically at the ideal irradiance of Gaussian distribution, which consists of 48 silicone solar cells. Using the ZEMAX optical simulation software, the realistic distribution of the Gaussian-like facula on the PV module has been modelled in a dish-type concentrator system. The experiments are done under the conditions of different alignments to imitate the different two-axis tracking accuracy with or without a homogenizer. Besides, the performances of dense-array modules with the classical uniform-sized and the proposed non-uniform-sized PV cells are analyzed under various illumination distributions using ZEMAX, respectively. Results show that when the deviation angle of tracking is 0, 0.02, 0.2, the photoelectric conversion efficiency and output power of the proposed non-uniform size dense-array module considerably exceeds the traditional uniform size module. Furthermore, when the tracking deviation angle is no more than 0.02°, it is a very definite possibility that the dish-type concentrator system with non-uniform-sized dense-array module need not a homogenizer as a secondary optical element, which may hence simplify the system structure.

Investigating the mix of strategic choices and performance of transaction platforms: Evidence from the crowdfunding setting

AbstractResearch SummaryThe platform literature offers keen insights on the pricing and non‐pricing strategies that transaction platforms undertake. We supplement this work by studying how platforms mix together their strategic choices and the association with platforms’ performance. To that end, we focus on crowdfunding platforms; a prominent setting of transaction platforms. We present an inductive large‐N study of the population of 788 crowdfunding platforms that operated in EU‐15 countries up to 2018. Our contribution is threefold: (a) identifying common mixes of strategic choices; (b) tracking deviations from these mixes; and (c) associating these with platforms’ survival and growth. We discuss our findings and how they advance knowledge at the intersection of the platform and strategic management literatures.Managerial SummaryNotable transaction‐platforms such as eBay, LinkedIn, and Tencent have an aggregate market‐value in the hundreds of billions of dollars. We know that platforms’ success is driven by the strategic choices they undertake. Yet, we know less about how they mix together these choices and the association with platforms’ performance. Our study addresses this gap by focusing on a prominent setting: crowdfunding. Using data on the population of 788 crowdfunding platforms in EU‐15 countries, we show that these platforms cluster around three common mixes of strategic choices. Moreover, crowdfunding platforms do not strictly adhere to the strategy mix they are affiliated with. Interestingly, there is a positive association between the degree to which a platform's choices differentiate from its strategy mix and platform's subsequent performance.

Integral terminal sliding mode control unified with UDE for output constrained tracking of mismatched uncertain non-linear systems

This paper presents a novel integral terminal sliding mode control (ITSMC) algorithm compounded with Barrier Lyapunov’s Function (BLF) for high precision output tracking objective of uncertain N-dimensional strict feedback class of non-linear systems subjected to non-infringement of system output constraint. Besides, the proposed algorithm also employs uncertainty and disturbance estimator (UDE) technique for abating the existence of unknown mismatched and matched uncertainties. Most of the preliminary SMC schemes encompass the UDE technique to cope with unknown matched uncertainties only. However, the presented method embodies the dynamic surface control (DSC) architecture to get rid of the matching architectural constraint in UDE approach as well as ‘complexity explosion’ concern in backstepping approach. Additionally, the introduced method also applies the notion of symmetric BLF to enforce strict bounds on output tracking deviation from its reference value. To emphasize on the strengths of devised methodology, two examples are simulated by comparing the derived outcomes with already existing techniques in literature.

Teleoperation of Collaborative Robot for Remote Dementia Care in Home Environments.

As a senile chronic, progressive and currently incurable disease, dementia has an enormous impact on society and life quality of the elderly. The development of teleoperation technology has changed the traditional way of care delivery and brought a variety of novel applications for dementia care. In this paper, a telerobotic system is presented which gives the caregivers the capability of assisting dementia elderly remotely. The proposed system is composed of a dual-arm collaborative robot (YuMi) and a wearable motion capture device. The communication architecture is achieved by the robot operation system (ROS). The position-orientation data of the operator’s hand are obtained and used to control the YuMi robot. Besides, a path-constrained mapping method is designed for motion trajectory tracking between the robot and the operator in the progress of teleoperation. Meanwhile, corresponding experiments are conducted to verify the performance of the trajectory tracking using the path-constrained mapping method. Results show that the position tracking deviation between the trajectory of the operator and the robot measured by dynamic time warping distance is 1.05 mm at the sampling frequency of 7.5 Hz. Moreover, the practicability of the proposed system was verified by teleoperating the YuMi robot to pick up a medicine bottle and further demonstrated by assisting an elderly woman in picking up a cup remotely. The proposed telerobotic system has potential utility for improving the life quality of dementia elderly and the care effect of their caregivers.