Short-range Guidance Research Articles

Machine learning-based electro-magnetic field guided localization technique for autonomous underwater vehicle homing

Precise guidance is the primary requirement for the reliable homing of autonomous underwater vehicles (AUV). The necessity for accurate short-range position tracking arises due to the limitations of the inertial sensors’ cumulative integral drift, unreliable acoustic positioning system in very short ranges, and non-propagation of high-frequency electromagnetic signals of the GPS system. In this article, a very low-frequency electro-magnetic (EM) field is generated for very short-range guidance for the homing operation of underwater vehicles. The design and modeling of the 3-axis low-frequency EM-based shallow water submerged Docking Station (DS) at 10 m depth is explained and the EM field is generated for a 20 m range in the 3-axis plane using two perpendicular coils operated in distinct frequencies. The stochastic magnetometer measurement model is used to estimate the relative kinematics of the underwater vehicle with respect to the EM docking coil. The EM field datasets generated from EM field maps around DS are used for training and validating with different Machine Learning (ML) algorithms. The designed ML aided EM-based tracking technique guidance algorithms are validated for underwater vehicle localization that requires a precise and reliable homing process to the DS even in turbid waters, bio-fouling environment, and reflective boundaries though it has limitations in presence of ambient ferromagnetic sources. Numerical simulations have been carried out with conventional methods and ML algorithms on the generated EM data. The results indicate that the position accuracy achieved is within 1% for ML-aided EM based guidance techniques when compared to the conventional algorithm which has a position accuracy of 3%. ML aided techniques are advantageous as they are independent of the dynamic ocean environment and the underwater vehicle configuration and the Time to Home (ToH) to the DS is simulated in different scenarios, is 160 s–200 s with a vehicle speed of 0.25 m/s. It is observed that the vehicle can choose the shortest path for homing operation with the measured EM field values and with aid of ML techniques.

Deep Learning Aided Magnetostatic Fields Based Real-Time Pose Estimation of AUV for Homing Applications

Autonomous underwater vehicles (AUVs) require a submerged docking station (DS) for recharging their batteries and data transfer purposes, in order to increase the vehicle endurance and updating its missions in the current subsea scenarios. Hence, a precise short-range guidance toward the DS is needed for AUVs for a reliable homing process in dynamic ocean environments. In this letter, a deep learning (DL) aided short-range guidance technique is proposed for reliable and precise homing of AUVs using an intelligent magnetic field guidance. A magnetic field is generated up to 20 m range from the dipole coil wound on the DS. The 64 bit microcontroller-based data acquisition system with a three-axis geomagnetic sensor embedded with DL hardware is developed as a prototype for estimating the AUV pose relative to the DS. A DL model is trained with the acquired magnetic field data with the coordinates of the AUV. The customized DL model is envisaged for predicting range and bearing angle simultaneously and has been developed with required hidden layers and activation functions. In this problem, the optimal DL model with two hidden layers and 64 neurons provides 94% accuracy in the prediction of AUV pose parameters i.e., range and bearing angle relative to DS. The DL model is embedded with the AUV hardware for real-time pose estimation of the AUV toward the DS. The proposed DL-based methodology is robust for AUV homing applications when compared to conventional approaches and machine learning techniques in dynamic environments.

Aviation radio control systems as complex technical systems. Part 1. Analysis of the possibilities of multicriteria optimization

The need to take into account the increasing requirements for expanding the field of application conditions, taking into account an increasingly wide range of possible conditions, increasing requirements for the volume and reliability of the information used, combined with increasing requirements for improving the efficiency of operation, predetermined the emergence of a new type of information management systems, called "complex technical systems" (CTS). In general, the CTS is understood as a set of functionally related control and information subsystems united by a common goal of joint solution of a group of tasks. The most striking example of CTS is aviation radio control (RC) systems, which are able to solve the general task of destroying targets in several stages, using various methods of route control and guidance on them in conditions of high initial uncertainty due to a variety of possible objects of influence of varying degrees of importance and the random nature of their spatial location. At the same time, the task of destroying objects of the opposing side is solved, as a rule, in several stages, including long-range (command), short-range guidance (homing) and the use of weapons. It should be emphasized that the choice of indicators of excellence that reflect various aspects of the functioning of the CTS (aircraft RC systems) is by no means a trivial task. Within the framework of the "system – environment" approach, which takes into account the specific conditions of the use of the CTS, in addition to performance indicators that reflect the degree of compliance of the system with its purpose, such indicators as functional stability (survivability), dynamism and informativeness are increasingly in demand, which, as a rule, contradict each other. It should be noted that due to the heterogeneity of the tasks being solved and the inconsistency of the requirements, it is necessary to take into account the need to use a multicriteria approach to the synthesis of control methods and information support algorithms. However, the methods of multicriteria optimization used in practice have a number of significant drawbacks that make it difficult to use them in the development of promising CTS (RC systems). At the same time, it is very tempting to use the mathematical apparatus of the statistical theory of optimal control (STOC) for multicriteria optimization of the CTS, which allows to avoid the above disadvantages to some extent. The expediency of using STOC for solving multicriteria problems is due to the fact that the very formulation of the STOC problem and the resulting optimization procedures already contain a solution to the two-criterion problem of obtaining a system that is jointly the best in both accuracy and costeffectiveness of management. The analysis of various approaches to solving multicriteria problems has shown that the most rational is to reduce them to a singlecriteria problem with further use as a basic variant of local STOC optimization.

Real time large scale in vivo observations reveal intrinsic synchrony, plasticity and growth cone dynamics of midline crossing axons at the ventral floor plate of the zebrafish spinal cord.

How axons are wiring the vertebrate spinal cord has in particular been studied at the ventral floor plate using fixed samples or looking at single growing axons with various microscopy techniques. Thereby may remain hidden important live organismal scale information concerning dynamics and concurrent timing of the many axons simultaneously crossing the floor plate. Here then, applying light-sheet microscopy, axonal growth and guidance at the floor plate are followed in vivo in real time at high resolution along several hundred micrometers of the zebrafish spinal cord by using an interneuron expressing GFP as a model axon. The commissural axons are observed crossing the ventral floor plate midline perpendicularly at about 20 microns/h and in a manner dependent on the Robo3 receptor. Commissural growth rate reaches a minimum at the midline, confirming previous observations. Ipsilateral axons extend concurrently, at three to six times higher growth rates. At guidance points, commissural axons are seen to decrease their growth rate and growth cones increase in size. Commissural filopodia appear to interact with the nascent neural network, and thereby trigger immediate plastic and reversible sinusoidal-shaped bending movements of neighboring commissural shafts. A simple protocol isolating single neuronal cells from the spinal cord is developed to facilitate further molecular characterization. The recordings show the strikingly stereotyped spatio-temporal control that governs midline crossing. The live observations give renewed perspective on the mechanisms of axonal guidance in the spinal cord that provide for a discussion of the current distinction between diffusible long-range versus substrate-bound short-range guidance cues.

The method of exact solution of the problem of short-range guidance with two turns

The task of determining the guidance parameters by the “two-turn maneuver” method is related to numerical solution of an equation defining the trajectory of the fighter-interceptor. We propose an easy-to-implement in software approach which is based on the exact solution of the problem at each step of the iterative process constructed by one of the parameters

Model Development and Hindcast Simulations of NOAA’s Integrated Northern Gulf of Mexico Operational Forecast System

NOAA’s National Ocean Service is upgrading three existing northern Gulf of Mexico (GOM) operational nowcast/forecast systems (OFS) by integrating them into one single system (INGOFS) and developing additional domain coverage to encompass the lower Mississippi River, Lake Pontchartrain, Texas coastal embayments, and Mexican coastal waters. The system will produce real-time nowcast and short-range forecast guidance for water levels, 3-dimensional currents, water temperature, and salinity. INGOFS will be implemented using the Finite Volume Community Ocean Model (FVCOM). This paper describes the model configuration and results from a one-year (2 August 2016–1 August 2017) hindcast simulation. The model grid is composed of about 300,000 nodes and 600,000 elements, and has a spatial resolution ranging from 45 m near the coast to around 10 km on the open ocean boundary. It uses the FVCOM wetting and drying feature, the quadratic bottom friction scheme, and the two-equation model of the Mellor-Yamada Level 2.5 turbulence closure scheme. The hindcast results of water levels, surface temperatures, and salinity were verified by comparing the model time series with in situ observations. The root-mean-squared errors are about 0.08 m for water levels, about 1.1 °C for temperatures, and about 3.7 psu for salinity. The hindcast configuration will be further tested in a nowcast/forecast environment for a one-year period. The upgraded system is anticipated to be in operational production in mid-2020.

Model Development and Hindcast Simulations of NOAA’s Gulf of Maine Operational Forecast System

The National Ocean Service (NOS) of National Oceanic and Atmospheric Administration is developing an operational nowcast/forecast system for the Gulf of Maine (GoMOFS). The system aims to produce real-time nowcasts and short-range forecast guidance for water levels, 3-dimensional currents, water temperature, and salinity over the broad GoM region. GoMOFS will be implemented using the Regional Ocean Model System (ROMS). This paper describes the system setup and results from a one-year (2012) hindcast simulation. The hindcast performance was evaluated using the NOS standard skill assessment software. The results indicate favorable agreement between observations and model forecasts. The root-mean-squared errors are about 0.12 m for water level, less than 1.5 °C for temperature, less than 1.5 psu for salinity, and less than 0.2 m/s for currents. It is anticipated to complete the system development and the transition into operations in fiscal year 2017.

Frazzled promotes growth cone attachment at the source of a Netrin gradient in the Drosophila visual system.

Axon guidance is proposed to act through a combination of long- and short-range attractive and repulsive cues. The ligand-receptor pair, Netrin (Net) and Frazzled (Fra) (DCC, Deleted in Colorectal Cancer, in vertebrates), is recognized as the prototypical effector of chemoattraction, with roles in both long- and short-range guidance. In the Drosophila visual system, R8 photoreceptor growth cones were shown to require Net-Fra to reach their target, the peak of a Net gradient. Using live imaging, we show, however, that R8 growth cones reach and recognize their target without Net, Fra, or Trim9, a conserved binding partner of Fra, but do not remain attached to it. Thus, despite the graded ligand distribution along the guidance path, Net-Fra is not used for chemoattraction. Based on findings in other systems, we propose that adhesion to substrate-bound Net underlies both long- and short-range Net-Fra-dependent guidance in vivo, thereby eroding the distinction between them.

Control over spacecraft center of mass movement during soft rendezvous with orbital object at the short-range guidance segment

Control over spacecraft center of mass movement during soft rendezvous with orbital object at the short-range guidance segment

Editorial: Mechanisms of Neuronal Migration during Corticogenesis.

Editorial: Mechanisms of Neuronal Migration during Corticogenesis.

Cellular projections from sensory hair cells form polarity-specific scaffolds during synaptogenesis.

The assembly of a nervous system requires the extension of axons and dendrites to specific regions where they are matched with appropriate synaptic targets. Although the cues that guide long-range outgrowth have been characterized extensively, additional mechanisms are required to explain short-range guidance in neural development. Using a complementary combination of time-lapse imaging by fluorescence confocal microscopy and serial block-face electron microscopy, we identified a novel type of presynaptic projection that participates in the assembly of the vertebrate nervous system. Synapse formation by each hair cell of the zebrafish's lateral line occurs during a particular interval after the cell's birth. During the same period, projections emerge from the cellular soma, extending toward a specific subpopulation of mature hair cells and interacting with polarity-specific afferent nerve terminals. The terminals then extend along the projections to reach appropriately matched presynaptic sites, after which the projections recede. Our results suggest that presynaptic projections act as transient scaffolds for short-range partner matching, a mechanism that may occur elsewhere in the nervous system.

Two specific populations of GABAergic neurons originating from the medial and the caudal ganglionic eminences aid in proper navigation of callosal axons

The corpus callosum (CC) plays a crucial role in interhemispheric communication. It has been shown that CC formation relies on the guidepost cells located in the midline region that include glutamatergic and GABAergic neurons as well as glial cells. However, the origin of these guidepost GABAergic neurons and their precise function in callosal axon pathfinding remain to be investigated. Here, we show that two distinct GABAergic neuronal subpopulations converge toward the midline prior to the arrival of callosal axons. Using in vivo and ex vivo fate mapping we show that CC GABAergic neurons originate in the caudal and medial ganglionic eminences (CGE and MGE) but not in the lateral ganglionic eminence (LGE). Time lapse imaging on organotypic slices and in vivo analyses further revealed that CC GABAergic neurons contribute to the normal navigation of callosal axons. The use of Nkx2.1 knockout (KO) mice confirmed a role of these neurons in the maintenance of proper behavior of callosal axons while growing through the CC. Indeed, using in vitro transplantation assays, we demonstrated that both MGE- and CGE-derived GABAergic neurons exert an attractive activity on callosal axons. Furthermore, by combining a sensitive RT-PCR technique with in situ hybridization, we demonstrate that CC neurons express multiple short and long range guidance cues. This study strongly suggests that MGE- and CGE-derived interneurons may guide CC axons by multiple guidance mechanisms and signaling pathways.

Cajal-Retzius Cells Instruct Neuronal Migration by Coincidence Signaling between Secreted and Contact-Dependent Guidance Cues

Cajal-Retzius (CR) cells are a transient cell population of the CNS that is critical for brain development. In the neocortex, CR cells secrete reelin to instruct the radial migration of projection neurons. It has remained unexplored, however, whether CR cells provide additional molecular cues important for brain development. Here, we show that CR cells express the immunoglobulin-like adhesion molecule nectin1, whereas neocortical projection neurons express its preferred binding partner, nectin3. We demonstrate that nectin1- and nectin3-mediated interactions between CR cells and migrating neurons are critical for radial migration. Furthermore, reelin signaling to Rap1 promotes neuronal Cdh2 function via nectin3 and afadin, thus directing the broadly expressed homophilic cell adhesion molecule Cdh2 toward mediating heterotypic cell-cell interactions between neurons and CR cells. Our findings identify nectins and afadin as components of the reelin signaling pathway and demonstrate that coincidence signaling between CR cell-derived secreted and short-range guidance cues direct neuronal migration.

Distinct expression patterns of syndecans in the embryonic zebrafish brain

Axon pathfinding in the neuroepithelium of embryonic brain is dependent on a variety of short and long range guidance cues. Heparan sulfate proteoglycans such as syndecans act as modulators of these cues and their importance in neural development is highlighted by their phylogenetic conservation. In Drosophilia, a single syndecan is present on the surface of axon growth cones and is required for chemorepulsive signalling during midline crossing. Understanding the role of syndecans in the vertebrate nervous system is challenging given that there are four homologous genes, syndecans 1–4. We show here that syndecans 2–4 are expressed in the zebrafish embryonic brain during the major period of axon growth. These genes show differing expression patterns in the brain which provides putative insights into their functional specificity.

Molecular and cellular mechanisms of lamina-specific axon targeting.

The specificity of synaptic connections is directly related to the functional integrity of neural circuits. Long-range axon guidance and topographic mapping mechanisms bring axons into spatial proximity of target cells and thus limit the number of potential synaptic partners. Synaptic specificity is then achieved by extracellular short-range guidance cues and cell-surface recognition cues. Neural activity may enhance the precision and strength of specific circuit connections. Here, we focus on one of the final steps of synaptic matchmaking: the targeting of synaptic layers and the mutual recognition of axons and dendrites within these layers.

Many Paths to Synaptic Specificity

The most impressive structural feature of the nervous system is the specificity of its synaptic connections. Even after axons have navigated long distances to reach target areas, they must still choose appropriate synaptic partners from the many potential partners within easy reach. In many cases, axons also select a particular domain of the postsynaptic cell on which to form a synapse. Thus, synapse formation is selective at both cellular and subcellular levels. Unsurprisingly, the nervous system uses multiple mechanisms to ensure proper connectivity; these include complementary labels, coordinated growth of synaptic partners, sorting of afferents, prohibition or elimination of inappropriate synapses, respecification of targets, and use of short-range guidance mechanisms or intermediate targets. Specification of any circuit is likely to involve integration of multiple mechanisms. Recent studies of vertebrate and invertebrate systems have led to the identification of molecules that mediate a few of these interactions.

Short-range guidance of autonomous vehicles—a comparative study

In this paper, two generic line-of-sight (LOS) sensing-based short-range guidance methodologies are presented for the docking of autonomous vehicles. The first method utilizes a passive LOS sensing scheme to provide vehicle corrective motions, while the latter method utilizes active sensing. The novelty of the proposed guidance methodologies is their applicability to situations that do not allow for direct proximity measurements of the vehicle. In such instances, one must employ a guidance-based technique to move the vehicle to its desired pose using corrective actions at the final stages of its motion. The objective of both proposed guidance methods is, thus, to successfully minimize the systematic errors of the vehicle, while allowing it to converge to its desired pose within random noise limits. Both techniques were successfully tested via simulations and are discussed herein in terms of convergence rate and accuracy, in addition to the types of localization problems that each method should be used in.

Using antibodies to direct axon regrowth

After a peripheral motor nerve injury, a complex series of events is set in motion. Within a few hours, the proximal side of the lesion closes with a membranous seal, through which axonal branches begin to emerge. The navigation of these branches is thought to be controlled by short-range guidance cues from the distal nerve stump, within which Schwann cells rearrange to support the new outgrowth. However, complete recovery is rare, on account of aberrant re-innervation of motor targets. Malfunctions in axon guidance cause targets to become innervated by ‘foreign’ axons, and supernumerary branching of axons leaving the proximal stump leads to simultaneous projection along several different fascicles. Recent work by Streppel et al. has addressed this problem from the point of view of axonal branching, looking at the extent to which a blockade of the growth factors known to be involved in this process can reduce erroneous re-innervation [1].

Some Questions of Safety And Efficiency Control of A Space Robotic Module's Flight Near by a Space Station

The problem of safety and economic control of a free-flying space robotic module during its flights near by a Space Station with using of the space robotic module single axis motion model (Rutkovsky and Sukhanov, 2000) is considered. A special method of short-range guidance for the translational motion's control is used. This method realises the module's motion along the corridors of safety (Kirchhof et al., 2000). An efficiency of the control is realized by decreasing of energy consumption for angular stabilization at the expense of the module main body turns as the result of "motions changing" between the main body and manipulators of the module.

Optimal and near-optimal take-off manoeuvres in the presence of windshear

This paper is concerned with the development of short-range forward-look guidance strategies for take-off manoeuvres in the presence of windshear, with reference to flight in the vertical and horizontal planes. In addition to the horizontal shear, the presence of a downdraught is assumed. First, two open-loop optimal escape strategies are considered, i.e. a performance maintaining strategy and a survival strategy, where it is assumed that the windshear is detected in an early stage of the encounter. Next, two closed-loop guidance strategies featuring short-range forward-look detection, which closely approximate the open-loop optimal solutions, are developed. Numerical results show that lateral manoeuvring, in which an aircraft is turned away from the microburst, improves the flight performance significantly in both optimal escape strategies. The simulation results demonstrate that the employed closed-loop guidance strategies are able to approximate closely the open-loop optimal trajectories, in both longitudinal and lateral escape manoeuvres.