Practical Tracking Research Articles

Practical consensus tracking control of multiple nonholonomic wheeled mobile robots in polar coordinates

SummaryThis paper proposes a sliding‐mode control (SMC) method to achieve practical cooperative consensus tracking for a network of multiple nonholonomic wheeled mobile robots (MNWMRs) with input disturbances. A novel SMC surface under the nonholonomic constraints is first formulated to characterize the network communication interactions among the networked robots under the framework of polar coordinates. A unified distributed consensus tracking strategy is then proposed by systematically combining a position controller and a direction controller. Furthermore, a simple yet general criterion is derived to achieve the desired practical consensus of trajectory tracking and posture stabilization for MNWMRs. In particular, for a specific common consensus trajectory, the complete asymptotic tracking in heading direction can be fully guaranteed when the perfect asymptotic position‐tracking errors are realized. Accordingly, the developed consensus tracking strategy for MNWMRs demonstrates some advantages of control performance including stability, robustness, and effectiveness over the existing control method proposed for their single‐robot counterparts. Some comparative simulation results are given to confirm the effectiveness of the proposed cooperative consensus control method.

Practical tracking control with prescribed transient performance for Euler-Lagrange equation

This paper is devoted to the practical tracking control with prescribed transient performance for a class of uncertain Euler-Lagrange (EL) equations. Remarkably, the system allows serious nonparametric uncertainties since all the system matrices are unknown and do not necessarily have known bounds. Moreover, the reference trajectory to be followed is more general since it does not necessarily have known bound or require to be twice-continuously differentiable but those of literature must do. For this, a funnel-based control scheme is proposed to overcome the serious uncertainties, and in turn to achieve certain prescribed closed-loop performance. Specifically, a funnel to which the tracking error belongs is first skillfully constructed with the aid of a time-varying function about a prescribed tracking accuracy parameter. Based on the funnel, a time-varying controller is designed which guarantees that all the closed-loop system signals are bounded while the tracking error evolves in the funnel set, that is, the system output tracks the reference trajectory with the prescribed convergence rate before the prescribed time. Finally, two application examples are used to validate the effectiveness of the theoretical results.

Practical detection and tracking of flying small objects in infrared images

Practical detection and tracking of flying small objects in infrared images

Practical torque tracking control of electro-hydraulic load simulator using singular perturbation theory

Nonlinear and high-order characteristics could directly hinder the application of many advanced control algorithms for electro-hydraulic system which is a coupling system with double-dynamics of mechanical and hydraulic components. In this paper, a practical torque tracking control using singular perturbation theory is proposed for electro-hydraulic load simulator. The system model is transformed into a singularly perturbed form including a slow mechanical system and a fast hydraulic system. To achieve high accuracy and strong robustness, an active disturbance rejection control based on desired model compensation is developed for the slow mechanical system. It is proved that the mechanical system with developed slow controller is exponentially stable. A proportional control law is employed for the fast hydraulic system. This hydraulic system with developed fast controller is demonstrated to be exponentially stable. Stability of the whole closed-loop system is theoretically analyzed using the extended Tikhonov’s theorem. Experimental results validate the presented control scheme.

Adaptive Tracking Control of Cooperative Robot Manipulators With Markovian Switched Couplings

Many cooperative robotic systems have not only modeling heterogeneity and uncertainty but also switched couplings, causing control difficulties. Here, we develop a neural network adaptive control framework for cooperative robot manipulators with unknown Euler–Lagrange dynamics and Markovian switched couplings. Second-order Markovian switching networks are used for modeling such cooperative robotic systems, which admit a hybrid neural network control with a desired tracking performance. The hybrid neural network control scheme contains a distributed adaptive controller and a hybrid adaptation law, enabling learning in the closed-loop system. The position and velocity tracking errors are shown to be practically uniformly exponentially stable in the mean-square sense, respectively, guaranteeing the second-order practical tracking. The results also suggest that the neural weight evolves with practical convergence to the ideal, showing the effect of network structure on the adaptation capacity.

Bounded Analysis and Practical Tracking Control of Complex Stochastic Nonlinear Systems with Unknown Control Coefficients

This paper mainly focuses on the output practical tracking controller design for a class of complex stochastic nonlinear systems with unknown control coefficients. In the existing research results, most of the complex systems are controlled in a certain direction, which leads to the disconnection between theoretical results and practical applications. The authors introduce unknown control coefficients, and the values of the upper and lower bounds of the control coefficients are generalized by constants to allow arbitrary values to be arbitrarily large or arbitrarily small. In the control design program, the design problem of the controller is transformed into a parameter construction problem by introducing appropriate coordinate transformation. Moreover, we construct an output feedback practical tracking controller based on the dynamic and static phase combined by Ito stochastic differential theory and selection of appropriate design parameters, ensuring that the system tracking error can be made arbitrarily small after some large enough time. Finally, a simulation example is provided to illustrate the efficiency of the theoretical results.

Realization of Exact Tracking Control for Nonlinear Systems via a Nonrecursive Dynamic Design

This paper investigates a novel nonrecursive tracking control law design for a class of nonlinear systems via dynamic output feedback. As the main contribution of this paper, a global nonrecursive tracking design procedure is first proposed to render a simple construction of a realizable output feedback control law, whose gain selections follow the conventional pole placement approach while the stability margin can be guaranteed via a sufficiently large scaling gain. By introducing a Lyapunov function which neglects the virtual controllers in essence, rigorous analysis is presented to ensure the global stability. In addition, finite-time and asymptotical tracking results can now be achieved within the same design framework whereas the tunable homogeneous degree plays as a key role. As another contribution, by proposing a saturated dynamic compensator, a less ambitious but practical control objective, namely semiglobal stability is achieved of the closed-loop system to relax the requirement of the restrictive growth conditions for global control design. Taking consideration of the case when system is subject to mismatched disturbances, a unified design and stability analysis framework shows that the practical tracking result can also be realized. A numerical example is provided to illustrate the effectiveness of the nonrecursive design and the simplicity of the proposed tracking control algorithm.

Improved generalized labeled multi-Bernoulli filter for non-ellipsoidal extended targets or group targets tracking based on random sub-matrices

For non-ellipsoidal extended targets and group targets tracking, using an ellipsoid to approximate the target extension may not be accurate enough because of lacking shape and orientation information. In consideration of this, we model a non-ellipsoidal extended target or target group as a combination of multiple ellipsoidal sub-objects, each represented by a random matrix. Besides, in practical tracking scenes, the knowledge of detection probability is of critical importance, which, however, is prior unknown due to the fluctuation of target parameters. Thus based on the aforementioned random sub-matrices model, an improved generalized labeled multi-Bernoulli (GLMB) filter is presented for the tracking of non-ellipsoidal extended targets or group targets in the case of unknown detection probability. In addition, a cheaper Gibbs sampling based joint prediction and updating implementation of the proposed GLMB filter is given, within which the extended targets or group targets are modeled using Beta gamma Gaussian inverse Wishart (BGGIW) distributions, achieving the estimation to detection probability, measurement rate, and extension state of each sub-object and the kinematic state with the positions of all sub-objects and unified kinematics for each extended target or target group. The simulation results demonstrate the effectiveness of the proposed filter.

Event-Triggered Tracking Control: a Discrete-Time Approach

In this work, the problem of designing event-triggered control strategies for disturbance rejection and reference tracking for discrete-time linear systems is addressed. Based on the Lyapunov theory, LMI-based conditions for the guarantee of perfect reference tracking/disturbance rejection under the proposed event-trigger strategy are derived. Furthermore, to avoid that the ETC strategy degenerates to a periodic one (in the case of non constant signals), a practical tracking/rejection solution considering a trade-off between the reduction of the control updates and the tolerance to a small error in steady state is proposed. The conditions are then casted in LMI-based optimization problems to compute the triggering functions aiming at reducing the control updates while ensuring the perfect or the practical tracking.

Tracking and Tracing for Data Mining Application in the Lithium-ion Battery Production

The production of Lithium-Ion Battery (LIB) cells is characterized by the interlinking of different production processes with a manifold of intermediate products. To be able to ensure high quality and enable a traceability of different production and product characteristics (e.g. energy consumption, material), a tracking and tracing concept is required. In this paper, a practical tracking and tracing concept throughout the production of LIB cells, enabling inline data-driven applications, is introduced. As a part of this concept an intelligent tracking and tracing platform is shown, which allows the generation of a pre-clustered data sets to facilitate future data-driven applications.

Nanjinganthus is an angiosperm, isn’t it?

ABSTRACT Nanjinganthus is an Early Jurassic angiosperm recognized based on the study of over 200 specimens. However, some other authors have misinterpreted these fossils. Here the authors try to remedy the problems, by pointing out the logical pitfalls in these publications and underscoring a long-used, workable criterion for early angiosperms. The paper explains the cons and pros of this criterion, hoping to bring palaeobotany and plant taxonomy back to a consistent and practical track. Nanjinganthus is an angiosperm.

Effects of the Carrier Phrase on Word-Recognition Performances by Younger and Older Listeners Using Two Stimulus Paradigms

Background: In the 1950s, with monitored live voice testing, the vu meter time constant and the shortdurations and amplitude modulation characteristics of monosyllabic words necessitated the use of the carrierphrase amplitude tomonitor (indirectly) the presentation level of the words. This practice continues withrecorded materials. To relieve the carrier phrase of this function, first the influence that the carrier phrasehas on word recognition performance needs clarification, which is the topic of this study.<br />Purpose: Recordings of Northwestern University Auditory Test No. 6 by two female speakers were usedto compare word recognition performances with and without the carrier phrases when the carrier phraseand test word were (1) in the same utterance stream with the words excised digitally from the carrier (VA-1speaker) and (2) independent of one another (VA-2 speaker). The 50-msec segment of the vowel in thetarget word with the largest root mean square amplitude was used to equate the target word amplitudes.<br />Research Design: A quasi-experimental, repeated measures design was used.<br />Study Sample: Twenty-four young normal-hearing adults (YNH; M = 23.5 years; pure-tone average[PTA] = 1.3-dB HL) and 48 older hearing loss listeners (OHL; M = 71.4 years; PTA = 21.8-dB HL) participatedin two, one-hour sessions.<br />Data Collection and Analyses: Each listener had 16 listening conditions (2 speakers 3 2 carrier phraseconditions 3 4 presentation levels) with 100 randomized words, 50 different words by each speaker.Each word was presented 8 times (2 carrier phrase conditions 3 4 presentation levels [YNH, 0- to24-dB SL; OHL, 6- to 30-dB SL]). The 200 recorded words for each condition were randomized as 8,25-word tracks. In both test sessions, one practice track was followed by 16 tracks alternated betweenspeakers and randomized by blocks of the four conditions. Central tendency and repeated measuresanalyses of variance statistics were used.<br />Results: With the VA-1 speaker, the overall mean recognition performances were 6.0% (YNH) and 8.3%(OHL) significantly better with the carrier phrase than without the carrier phrase. These differences werein part attributed to the distortion of some words caused by the excision of the words from the carrierphrases. With the VA-2 speaker, recognition performances on the with and without carrier phrase conditionsby both listener groups were not significantly different, except for one condition (YNH listeners at8-dB SL). The slopes of the mean functions were steeper for the YNH listeners (3.9%/dB to 4.8%/dB) thanfor the OHL listeners (2.4%/dB to 3.4%/dB) and were <1%/dB steeper for the VA-1 speaker than for theVA-2 speaker. Although the mean results were clear, the variability in performance differences betweenthe two carrier phrase conditions for the individual participants and for the individual words was strikingand was considered in detail.<br />Conclusion: The current data indicate that word recognition performances with and without the carrierphrase (1) were different when the carrier phrase and target word were produced in the same utterancewith poorer performances when the target words were excised from their respective carrier phrases(VA-1 speaker), and (2) were the same when the carrier phrase and target word were produced as independentutterances (VA-2 speaker).<br />See the Supplementary Data tab for supplementary materials.

Global output tracking by state feedback for high-order nonlinear systems with time-varying delays

This paper focuses on the problem of global practical output tracking for a class of high-order non-linear systems with time-varying delays (via state feedback). Under mild growth conditions on the...

Novel Generalized Predictive Control for Photoelectric Tracking System Based on Improved Objective Function and Predictive Value Correction

Novel generalized predictive control (GPC) is proposed to deal with the problems of cumulative deviation of the predicted value, long control process and large noise that often encountered in conventional GPC. First, the objective function of GPC is improved based on integral time square error (ITSE) criterion, and the output expression under soft constraint is deduced. Then, the predicted value is corrected by adopting the integral weighting method, the convergence of which is demonstrated. Finally, both the simulations and hardware experiments are conducted in a practical photoelectric tracking system. It turns out that the superiority of the improved GPC in control precision, dynamic response and robustness is verified.

Global Practical Tracking for a Hovercraft with Unmeasured Linear Velocity and Disturbances

This paper addresses the design and experimental validation of a trajectory tracking controller for an underactuated hovercraft with unmeasured linear velocity and subject to time-varying disturbances. The unmeasured linear velocity and disturbances are recovered by designing nonlinear observers. A control law is proposed that, in closed-loop with the velocity and disturbance observers, can robustly steer the hovercraft toward and stay within a neighborhood of a reference trajectory. To demonstrate the performance and robustness of the proposed control strategy, we present and analyze experimental results obtained with a model-scale hovercraft.

Fully Adaptive Practical Time-Varying Output Formation Tracking for High-Order Nonlinear Stochastic Multiagent System With Multiple Leaders.

Fully adaptive practical time-varying output formation tracking issues of high-order nonlinear stochastic multiagent systems with multiple leaders are researched, where the adaptive fuzzy-logic system (FLS) is introduced for estimating the mismatched integrated uncertain items. Distinctive with former results, stochastic noise is considered in the dynamics, and the followers are required for achieving the time-varying output formation tracking in probability of the convex combination of the leaders' outputs. First, a fully adaptive practical time-varying output formation tracking protocol is put forward, which only utilizes the neighboring relative information, and the global interaction topology information is not used. Besides, the designed protocol employs the adaptive FLSs to estimate the mismatched uncertainties of the followers and the leaders, and the uncertain boundary functions of the stochastic noise. Then, the design process of control protocol and parameter adaptive update law is summarized within four steps in an algorithm. Third, the stability and the properties of the proposed protocol and algorithm are analyzed by employing the Lyapunov theories and stochastic stability theories. Finally, numerical simulation results illustrate the effectiveness of achieved protocol and algorithm.

Practical formation‐containment tracking for multiple autonomous surface vessels system

Practical formation-containment tracking issues for the multiple autonomous surface vessels system with multiple leader vessels are considered. The follower vessels' states are designed to track the convex combination of the leader vessels' states, which are required to actualise the predefined time-varying formation tracking. Firstly, this study establishes the dynamic models of the multiple vessels system, where the outer-loop kinematic model and inner-loop dynamic model are considered simultaneously. Then, the practical formation-containment tracking protocols are devised based on distributed extended state observers, where the mismatched uncertainties and leader vessels' control input signals are estimated and compensated. Thirdly, an algorithm is presented to give the procedures for designing the control protocols, in which the feasible time-varying formations of leader's vessels are raised. A series of linear matrix inequalities are solved for obtaining the control parameters. Sufficient conditions for actualising the practical formation-containment tracking are derived. Finally, numerical simulation results reveal the effectiveness of the acquired theories.

Robust Path Tracking by a Dubins Ground Vehicle

The robust linear tracking technique is applied to a practical path tracking problem for a ground vehicle modeled as a Dubins car. The tracking control is designed based on the optimal strategy in an auxiliary linear-quadratic differential game for a linearized vehicle model. In contrast with a purified theoretic setup, the real-life problem is complicated by a nonconstant speed and control saturation. Moreover, the actual path generating control can be unknown to the tracking strategy designer. These issues required additional design blocks: speed tracking loop and leading angle differentiation, both based on similar tracking algorithms. The saturation effect is considered by using command reinforcement. Numerical and experimental results are presented and compared. Robustness with respect to unknown disturbances is demonstrated. Novel analytic results on the tracking error/control effort tradeoff are also presented.

Large-Angle Velocity-Free Attitude Tracking Control of Satellites: An Observer-Free Framework.

The challenging problem on the design of a large-angle attitude tracking controller for rigid satellites without angular velocity measurements is investigated in this article. An efficient and practical angular velocity-free control strategy with a simple, yet efficient structure is proposed. The attitude tracking maneuver is accomplished with the desired attitude pointing accuracy ensured despite disturbances. Compared with the existing observer-based velocity-free schemes, no observer is embedded into the control scheme. The developed approach can be implemented online and in real time. It does not require expensive online computation, enabling its convenient application to practical large-angle attitude tracking maneuvers. The presented control solution is numerically and experimentally validated on a rigid satellite testbed.

Image Tracking of Rotating Scene Based on Fusion of MEMS-IMU Data and Vision Data

Image tracking is a research field in constant evolution due to the new technological advances. The limited-space and low-cost features of missiles restrict the application and development of image tracking. Missile-borne image guidance system is still facing a series of difficult issues of anti-interference. This paper constructs a practical image tracking model using Kalman Filter based on fusion of MEMS-IMU Data and Vision Data after deriving the transformation matrix between the image sequences and MEMS-IMU data. The tracking model is tested by experiments. The result shows tracking based on fusion of MEMS-IMU Data and Vision Data is an effective solution of rotating scene and tracking accuracy is about 4 times better than vision only. The achievements can be not only used in military field such as Precision Guided Weapons and Photoelectric Reconnaissance Device, but also broadly applied in commercial products such as Virtual Reality, Intelligent Robot, Unmanned Airborne Vehicle and so on.