Control Effectors Research Articles

Tracking Control Based on Control Allocation with an Innovative Control Effector Aircraft Application

This paper proposes a control allocation method for the tracking control problem of a class of morphing aircraft with special actuators which are different from the conventional actuation surfaces. This design of actuators can bring about some potential advantages to the flight vehicles; however, due to the integral constraints, the desired control cannot be performed accurately; therefore, it leads to undesirable tracking errors, so influencing the performance of the system. Because the system could be control allocated, based on the designed cost function that describes the tracking errors, the cuckoo search algorithm (CSA) is introduced to search for the optimum solution within the calculated actuator execution commands that are equivalent to the desired commands. Several improvement measures are proposed for boosting the efficiency of the CSA and ensuring reasonable solutions. Simulation results show that the proposed control allocation method is necessary and effective, and the improvement measures are helpful in obtaining the optimum solution.

Trim and Structural Optimization of Subsonic Transport Wings Using Nonconventional Aeroelastic Tailoring

Several minimum-mass aeroelastic optimization problems are solved to evaluate the effectiveness of a variety of novel tailoring schemes for subsonic transport wings. Aeroelastic strength and panel buckling constraints are imposed across several trimmed maneuver loads, in addition to flutter constraints. Tailoring with metallic thickness variations, functionally graded materials, composite laminates, tow steering within composite laminates, and distributed trailing-edge control effectors are all found to provide reductions in structural wing mass with varying degrees of success. The question as to whether this wing mass reduction will offset the increased manufacturing cost is left unresolved for each case.

Flight Control with Optimal Control Allocation Incorporating Structural Load Feedback

Advances in sensors and avionics computation power suggest real-time structural load measurements could be used in flight control systems for improved safety and performance. A conventional transport flight control system determines the moments necessary to meet the pilot’s command while rejecting disturbances and maintaining stability of the aircraft. Control allocation is the problem of converting these desired moments into control effector commands. In this paper, a framework is proposed to incorporate real-time structural load feedback and structural load constraints in the control allocator. Constrained optimal control allocation can be used to achieve desired moments without exceeding specified limits on monitored load points. Furthermore, certain criteria can be minimized, such as loads on certain parts of the aircraft. Flight safety issues can be addressed by using system health monitoring information to change control allocation constraints during flight. The framework to incorporate structural loads in the flight control system and an optimal control allocation algorithm are described and demonstrated on a nonlinear simulation of a generic transport aircraft with flight dynamics and static structural loads.

Regulation of kinetochore-microtubule attachments through homeostatic control during mitosis.

Faithful chromosome segregation during mitosis is essential for genome integrity and is mediated by the bi-oriented attachment of replicated chromosomes to spindle microtubules through kinetochores. Errors in kinetochore-microtubule (k-MT) attachment that could cause chromosome mis-segregation are frequent and are corrected by the dynamic turnover of k-MT attachments. Thus, regulating the rate of spindle microtubule attachment and detachment to kinetochores is crucial for mitotic fidelity and is frequently disrupted in cancer cells displaying chromosomal instability. A model based on homeostatic principles involving receptors, a core control network, effectors and feedback control may explain the precise regulation of k-MT attachment stability during mitotic progression to ensure error-free mitosis.

Midline 1 controls polarization and migration of murine cytotoxic T cells.

Midline 1 (MID1) is a microtubule-associated ubiquitin ligase that regulates protein phosphatase 2 A levels. Loss-of-function mutations in MID1 lead to the human X-linked Opitz G/BBB (OS) syndrome characterized by defective midline development during embryogenesis. We have recently shown that MID1 is strongly up-regulated in murine cytotoxic T lymphocytes (CTLs), and that it has a significant impact on exocytosis of lytic granules and the killing capacity of CTLs. The aims of the present study were to determine the localization of MID1 in migrating CTLs, and to investigate whether MID1 affects CTL polarization and migration. We found that MID1 mainly localizes to the uropod of migrating CTLs and that it has a substantial impact on CTL polarization and migration in vitro. Furthermore, analysis of contact hypersensitivity responses supported that MID1 controls effector functions of CTLs in hapten-challenged skin in vivo. These results provide significant new knowledge on the role of MID1 in CTL biology.

A complex immunological idiotypic network for maintenance of tolerance.

A complex immunological idiotypic network for maintenance of tolerance.

Adaptive neural observer‐based backstepping fault tolerant control for near space vehicle under control effector damage

In this study, a theoretical framework for reconfigurable flight control is developed and applied to near space vehicle (NSV) attitude dynamics. First, NSV reentry mode is described. Second, an adaptive neural network observer is proposed, which ensures asymptotic convergence of the state observer error to zero under control effector damage and uncertainty. Next, a reconfigurable command-filter backstepping controller is designed based on the adaptive neural network observer. The authors focus is on the accommodation of the control effector damage, uncertainty and resulting disturbances. It is shown that the presented new control design results in asymptotic convergence of the attitude tracking error to zero. Finally, simulation results are given to demonstrate the effectiveness and potential of the proposed fault tolerant control scheme.

Attitude Control of Flying Wing UAV Based on Active Disturbance Rejection Control and Multi-Object Nonlinear Control Allocation

For the attitude control of flying wing UAV, need to consider the problems of model parameters perturbation and external disturbances, and resolve the special problems of redundant control surfaces and nonlinear control efficiency. The control problem of attitude tracking is investigated based on active disturbance rejection control (ADRC) and multi-object nonlinear control allocation. ESO are designed to estimate and compensate for disturbance. It can improve both the robustness and control performance of the control system. Control allocation make full use of the redundant control effectors to realize the integrated tradeoff multi-object control allocation under varying flight conditions and missions.

Ellagic acid inhibits adipocyte differentiation through coactivator-associated arginine methyltransferase 1-mediated chromatin modification

Chromatin remodeling is a key mechanism in adipocyte differentiation. However, it is unknown whether dietary polyphenols are epigenetic effectors for adiposity control. Ellagic acid (EA) is a naturally occurring polyphenol in numerous fruits and vegetables. Recently, EA-containing foods have been reported to reduce adiposity. In the present study, we sought to determine whether EA inhibits adipogenesis by modifying chromatin remodeling in human adipogenic stem cells (hASCs). qPCR microarray of chromatin modification enzymes revealed that 10 μmol/L of EA significantly inhibits histone deacetylase (HDAC)9 down-regulation. In addition, EA was associated with up-regulation of HDAC activity and a marked reduction of histone acetylation levels. However, chemical inhibition of HDAC activity or depletion of HDAC9 by siRNA were not sufficient to reverse the antiadipogenic effects of EA. Intriguingly, EA treatment was also associated with reduced histone 3 arginine 17 methylation levels (H3R17me2), implying the inhibitory role of EA in coactivator-associated arginine methyltransferase 1 (CARM)1 activity during adipogenesis. Boosting CARM1 activity by delivering cell-penetrating peptides of CARM1 not only recovered H3R17me2 but also restored adipogenesis evidenced by H3 acetylation at lysine 9, HDAC9 down-regulation, PPARγ expression and triglyceride accumulation. Taken together, our data suggest that reduced CARM1 activity by EA results in a decrease of H3R17me2 levels, which may interrupt consecutive histone remodeling steps for adipocyte differentiation including histone acetylation and HDAC9 dissociation from chromatin. Our work provides the mechanistic insights into how EA, a polyphenol ubiquitously found in fruits and vegetables, attenuates human adipocyte differentiation by altering chromatin remodeling.

Active fault‐tolerant control for near space vehicles based on reference model adaptive sliding mode scheme

SUMMARYIn this paper, an adaptive sliding mode (ASM) scheme is proposed for fault identification and fault‐tolerant control of near space vehicles (NSVs). First, the attitude dynamic model is introduced, and a baseline controller based on reference sliding mode scheme is designed in the case of no faults. Then fault parameterizations with actuator dynamics is presented for several classes of faults: lock‐in‐place, float, hard‐over, and loss of effectiveness. On the basis of adaptive observer design, fault parameters can be accurately estimated on‐line. Furthermore, an ASM fault‐tolerant controller is designed for both cases of actuator dynamic faults and control effector damage. Finally, simulation experiments show that the proposed ASM scheme is able to quickly and accurately identify faults and reconfigure the controller, resulting in excellent overall system performance. Copyright © 2012 John Wiley & Sons, Ltd.

High-Efficiency Thrust Vector Control Allocation

A generalized approach to the allocation of redundant thrust vector slew commands for multi-actuated launch vehicles is presented, where deflection constraints are expressed as omniaxial or elliptical deflection limits in gimbal axes. More importantly than in the aircraft control allocation problem, linear allocators (pseudoinverses) are preferred for large booster applications to facilitate accurate prediction of the control-structure interaction resulting from thrust vectoring effects. However, strictly linear transformations for the allocation of redundant controls cannot, in general, access all of the attainable moments for which there is a set of control effector positions that satisfies the constraints. In this paper, the control allocation efficiency of a certain class of linear allocators subject to multiple quadratic constraints is analyzed, and a novel single-pass control allocation scheme is proposed that augments the pseudoinverse near the boundary of the attainable set. The controls are determined over a substantial volume of the attainable set using only a linear transformation; as such, the algorithm maintains compatibility with frequency-domain approaches to the analysis of the vehicle closed-loop elastic stability. Numerical results using a model of a winged reusable booster system illustrate the proposed technique’s ability to access a larger fraction of the attainable set than a pseudoinverse alone.

Blended wing body lateral-directional stability investigation using 6DOF simulation

Presently at the Von Karman Institute for Fluid Dynamics, a comprehensive research investigation is being performed on the lateral-directional stability characteristics of a business jet class blended wing body. This paper presents an innovative MATLAB-based methodology using a multi-disciplinary design and optimization code written by the author, which combines various flow solvers, structural solvers, and aircraft design equations, to gain a comprehensive understanding of the overall vehicle performance while simultaneously creating a database for six-degrees-of-freedom (6DOF) flight simulation. Initial validation of the design was achieved through the Monte Carlo analysis of a 6DOF flight simulator, testing the take-off and landing flight regimes where the blended wing body is prone stall and departure due to asymmetric flow over the wing. Differential control effectors on the bottom of the wing, called “belly-flaps,” are investigated for lateral-directional control. Initial test results show that optimal span is 20% b/2, chord 20% [Formula: see text], located at 62% croot, with zero separation from vehicle centerline.

An Anticipative Control Approach and Interactive GUI to Enhance the Rendering of the Distal Robot Interaction with its Environment during Robotized Tele-Echography

Performing a robotized telemedicine act via specific networks brings forth the issue of transparency in order to enable the operator, e.g. the medical ultrasound specialist, to safely and accurately perform bilateral tele-operation tasks despite the long time delays inherent to the communication link. To counter these effects, two strategies are combined to improve, at the operator site, the rendering of the interactions between the remote robotic systems with its environment (i.e. the patient), and the control of the robot’s orientation at the operator site. The first approach is the development of a new control architecture based on an internal model providing an anticipated value of the distant environment stiffness; it is complemented with a graphic user interface (GUI) which provides the expert with the real-time relative position of the haptic probe with the robot’s end effector for better tele-operated control. These combined strategies provide the expert with an improved interactive tool for tele-diagnosis.

Robust control allocation with adaptive backstepping flight control

For the enhancement of survivability and maneuverability, modern aircraft systems have redundant control effectors. Control allocation is a useful method for distributing control signals among the individual effectors. In order to implement a control allocation scheme, the control system is designed using two-step procedures. In the first step, the control law is designed by adaptive backstepping control. The second step is to design the control allocator. A robust control allocation method is presented in this paper, which is motivated from the concept of the worst-case robust approximation approach. By assuming uncertainties in the control effectiveness matrix, the worst-case robust control allocation problem is investigated. The proposed robust control allocation technique is compared with weighted least squares control allocation. In particular, nonlinear simulations demonstrate that the proposed robust control allocation method has satisfactory performance and robustness for the assumed uncertainties in the control effectiveness matrix.

Interferon α/β receptor signaling plays a critical role in regulatory T cell development and function (P1093)

Abstract Type I IFNs are a family of cytokines with both antiviral and immunomodulatory properties. While the antiviral effects are appreciated, the immunomodulatory properties are less clear. Given the immunomodulatory properties of Treg, we have considered a possible role for IFNα/βR signaling in Treg development/function. Treg from WT and IFNα/βR deficient (-/-) mice were equal in number and in vitro/in vivo suppressive activity. Therefore, we set up a model to test IFNα/βR-/- Treg fitness in a competitive environment using bone marrow chimeras reconstituted with a 1:1 mixture of WT and IFNα/βR-/- cells. While the WT to IFNα/βR-/- ratio of all T cells was significantly skewed toward WT in these mice, skewing was most pronounced in the Treg compartment. The disadvantage of the IFNα/βR-/- Treg in the competitive environment was likely due to a defect in development and/or survival, as the ratio of IFNα/βR-/- Treg was markedly decreased in the thymus, and peripheral IFNα/βR-/- Treg had a significantly higher frequency of active caspase positive cells. The fitness of IFNα/βR-/- Treg was further examined in a disease model by testing their capacity to rescue the scurfy disease phenotype. IFNα/βR-/- Treg in chimeric mice reconstituted with scurfy and IFNα/βR-/- bone morrow were unable to control effector T cell activation and tissue inflammation. Collectively, these data demonstrate a critical role for IFNα/βR signaling in the development and/or survival of Treg.

Role of MGL and galectin-1 cross-talk in the regulation of T cell apoptosis (P1288)

Abstract Recently we showed that the interaction of MGL, expressed by tolerogenic dendritic cells (DCs), with GalNAc-decorated CD45 on effector cells inhibits T cell function leading to T cell death. The LacNAc binding lectin Gal1 also binds CD45 inducing apoptosis of Th1 and Th17 effector T cells. However, whether these lectins may act in concert to control effector T cell functions remain to be explored. Firstly, we incubated both lectins with Jurkat T cells and measured apoptosis by annexin V. We found higher and faster apoptosis induction compared to each lectin alone. A mechanistic analysis of this result by ImageStream® technology revealed that MGL triggers Gal1 expression that later colocalizes with CD45 in the membrane inducing high levels of receptor clustering and, in this manner, leads to augmented apoptosis. This effect is CD45 mediated and T cell specific, since Jurkat T cells devoid of this receptor or CD45-expressing carcinoma or adenocarcinoma cell lines are protected from apoptosis when incubated with MGL. Next, we isolated and activated mouse CD4+ T cells and showed that MGL1 but not MGL2 homologue induces apoptosis. However, there is no additive effect in primary CD4+ T cells. Although more work is required to fully elucidate the observed effects, these results indicate that both MGL and Gal1 may modify effector T cell function, through the interaction with specific CD45 glycoforms, potentially contributing to the homeostasis of the immune response.

AMPK: a metabolic switch for CD8+ T-cell memory.

Adenosine monophosphate-activated protein kinase (AMPK) is a serine/threonine kinase and is crucial for cellular energy homeostasis. The exact role of AMPK during memory CD8(+) T-cell differentiation, a process that changes from the metabolically active state of effector T cells to one of quiescence in memory cells is not well understood; however, a report by Cantrell and colleagues [Eur. J. Immunol. 2013. 43: 889-896] in this issue of the European Journal of Immunology shows that AMPK, by sensing glucose stress, is an important upstream molecule of mammalian target of rapamycin (mTOR) complex 1 for memory CD8(+) T-cell differentiation. This study provides new insights into how AMPK monitors energy stress to control effector and memory CD8(+) T-cell formation as discussed in this Commentary.

Novel robust control framework for morphing aircraft

This paper develops a robust control methodology for a class of morphing aircraft, which is called innovative control effector (ICE) aircraft. For the ICE morphing aircraft, the distributed arrays of hundreds of shape-change devices are employed to stabilize and maneuver the air vehicle. Because the morphing aircraft have the inherent uncertainty and varying dynamics due to the alteration of their configuration, a desired control performance can not be satisfied with a fixed feedback controller. Therefore, a novel control framework including an adaptive flight control law and an adaptive allocation algorithm is proposed. Firstly, a state feedback adaptive control law is designed to guarantee closed-loop stability and state tracking in the presence of uncertain dynamics caused by the wing shape change due to different flight missions. In the control allocation, many distributed arrays are managed in an optimal way to improve the robustness of the system. The scheme is used to an uncertain morphing aircraft model, and the simulation results demonstrate their performance.

ChemInform Abstract: Synthesis of Oligonucleotide‐Peptide Conjugates for Biomedical and Technological Applications

AbstractReview: 19 refs.

What nervous systems do: early evolution, input–output, and the skin brain thesis

Nervous systems are standardly interpreted as information processing input–output devices. They receive environmental information from their sensors as input, subsequently process or adjust this information, and use the result to control effectors, providing output. Through-conducting activity is here the key organizational feature of nervous systems. In this paper, we argue that this input–output interpretation is not the most fundamental feature of nervous system organization. Building on biological work on the early evolution of nervous systems, we provide an alternative proposal: the skin brain thesis (SBT). The SBT postulates that early nervous systems evolved to organize a new multicellular effector: muscle tissue, the primary source of animal motility. Early nervous systems provided a new way of inducing and coordinating self-organized contractile activity across an extensive muscle surface underneath the skin. The main connectivity in such nervous systems runs across a spread out effector and is transverse to sensor-effector signaling. The SBT therefore constitutes a fundamental conceptual shift in understanding both nervous system operation and what nervous systems are. Nervous systems are foremost spatial organizers that turn large multi-cellular animal bodies into dynamic self-moving units. At the end, we briefly discuss some theoretical connections to central issues within the behavioral, cognitive and neurosciences.