Entry Vehicle Research Articles

A Distributionally Robust Fusion Framework for Autonomous Multisensor Spacecraft Navigation during Entry Phase of Mars Entry, Descent, and Landing

A robust multisensor navigation filter design for the entry phase of next-generation Mars entry, descent, and landing (EDL) is presented. The entry phase is the longest and most uncertain portion of a Mars landing sequence. Navigation performance at this stage determines landing precision at the end of the powered descent phase of EDL. In the present work, measurements from a ground-based radio beacon array, an inertial measurement unit (IMU), as well as an array of atmospheric and aerothermal sensors on the body of a Mars entry vehicle are fused using an M-estimation-based iterated extended Kalman filtering (MIEKF) framework. The multisensor approach enables an increased positioning accuracy as well as the estimation of parameters that are otherwise unobservable. Furthermore, owing to the proposed statistically robust filter formulation, states and parameters can be accurately estimated in the presence of non-Gaussian measurement noise. Deviations from normally distributed observation noise correspond to outlier events such as sensor faults or other sources of spurious sensor data such as interference. The proposed framework provides a significant reduction in estimation error at the parachute phase of EDL, thereby increasing the likelihood of a pinpoint landing at a chosen landing site. Six states and three parameters are estimated. The suggested method is compared to the extended Kalman filter (EKF) and the unscented Kalman filter (UKF). Detailed simulation results show that the presented fusion architecture is able to meet future pinpoint planetary landing requirements in realistic sensor measurement scenarios.

A deep learning-based approach to time-coordination entry guidance for multiple hypersonic vehicles

AbstractA multiple-vehicles time-coordination guidance technique based on deep learning is suggested to address the cooperative guiding problem of hypersonic gliding vehicle entry phase. A dual-parameter bank angle profile is used in longitudinal guiding to meet the requirements of time coordination. A vehicle trajectory database is constructed along with a deep neural network (DNN) structure devised to fulfill the error criteria, and a trained network is used to replace the conventional prediction approach. Moreover, an extended Kalman filter is constructed to detect changes in aerodynamic parameters in real time, and the aerodynamic parameters are fed into a DNN. The lateral guiding employs a logic for reversing the sign of bank angle, which is based on the segmented heading angle error corridor. The final simulation results demonstrate that the built DNN is capable of addressing the cooperative guiding requirements. The algorithm is highly accurate in terms of guiding, has a fast response time, and does not need inter-munition communication, and it is capable of solving guidance orders that satisfy flight requirements even when aerodynamic parameter disruptions occur.

RFID Based Vehicle Entry System

Abstract: Each organization provides transportation vehicles and employs people to keep records of the entry and exit of those vehicles. The entry and exit times of vehicles are recorded using RFID. Radio frequency identification (RFID) is a wireless technology system consisting of her two components of a tag and a system. Radio frequency identification (RFID) is also used for vehicle monitoring. How the use of electromagnetic or capacitive coupling in the high-frequency portion of the electromagnetic spectrum draws attention to objects, animals, or people. An RFID chip contains a radio transmitter that transmits a coded identification number when interrogated by a reader. Some of his RFID tags can be inspected from a few meters away, out of sight of the reader. Bulk reads allow near-parallel analysis of tags. This small type is incorporated into customer products for identification and even implanted in pets. RFID has many uses in our daily life. Tags can be attached to any object and used to track and manage inventory, people, and more. For example, it can be attached to vehicles, laptops, books, cell phones, etc., and the owner or student can use her Google spreadsheet to track the vehicle by location. User can scan her QR or access Google Sheets

Flow and radiation modeling over a Martian entry vehicle

The high-temperature shock layer around re-entry vehicles strongly emits radiation through atomic lines and molecular bands. Radiative heat transfer strongly affects boundary layer flow and heat transfer. A novel spectral model based on k-distribution is implemented and coupled with a hypersonic flow solver in OpenFOAM to simulate heat transfer over a Martian entry vehicle. The Navier-Stokes equations with finite rate chemistry are used to model hypersonic chemically reacting flows. The convective terms in the governing equations are treated with various flux schemes (HLL, AUSM+, Kurganov, and Tadmor). The non-gray radiative properties of shock layer gases were modeled with the Emission-weighted Full Spectrum k-distribution (EFSK) method. The Radiative Transfer Equation (RTE) is solved with the P1 radiative solver to calculate the wall heat flux and radiative heat source term. At a high Mach number, the radiative heat flux is dominant compared to the convective heat flux. The numerical results for Mach number 26 are compared with published data and are found to be in good agreement. All the flux schemes provided results in close agreement, with minor differences, especially near the wall for the AUSM+ flux scheme.

3D ray tracing solver for communication blackout analysis in atmospheric entry missions

During the atmospheric entry phase at hypersonic speed, the radio communication from/to a space vehicle can be disrupted due to the formation of a plasma sheath within the surrounding flow field. In order to characterize such communication blackout phases, this work presents a numerical methodology combining Computational Fluid Dynamic (CFD) simulations of ionized chemically reacting entry flows by means of Computational Object-Oriented Libraries for Fluid Dynamics (COOLFluiD) and a ray tracing analysis by means of the newly developed BlackOut RAy Tracer (BORAT). The latter is based on the numerical solution of the 3D Eikonal system of equations, offering a fast, efficient and accurate method to analyse the interaction between electromagnetic signals and weakly ionised plasmas. The proposed methodology, and BORAT in particular, is first verified on popular benchmark cases and then used to analyse the European Space Agency (ESA) 2016 ExoMars Schiaparelli entry flight into Martian environment. The corresponding results demonstrate the validity of the proposed ray tracing approach for predicting communication blackout, where signals emitted from the on-board antenna undergo reflection and refraction from the plasma surrounding the entry vehicle, and the advantage of a 3D approach for analysing real flight configuration.

IoT-Enabled Smart Parking: Enhancing Efficiency and Sustainability in Smart Cities

The field of smart parking is growing rapidly and has many potential applications in densely populated urban areas. Internet of Things (IoT) and Arduino-based smart parking systems offer an innovative solution to solve parking problems in real time. Among other things, these systems reduce traffic congestion, improve road safety, reduce greenhouse gas emissions, and improve user experience. In this paper, we present a smart parking system that uses an innovative architecture and algorithm to optimize vehicle parking. The system also tracks cars, their location, entry and exit details, and account management. An infrared sensor is integrated into the system to monitor the entry and exit of vehicles. This sensor uses beams of light to detect the presence of vehicles in a specific parking area, allowing for efficient use of available parking space. This project has many benefits, such as optimized space utilization, reduced congestion and pollution, and an improved user experience. The system can be deployed in a variety of environments, including underground parking garages, shopping malls, airports, and train stations.

Urban emissions cut: Russian and Chinese experience

This study is aimed at analyzing the opinions and proposals of scientists from Russia and China on reducing harmful emissions into the atmosphere produced by urban transport. Many factors of air pollution are similar in the cities of these countries. Therefore, Chinese and Russian researcher’ proposals could be mutually useful for solving issues of improving air quality and reducing emissions. The study is based on a comprehensive data analysis. First of all, the Air Quality Index in the cities of China and Russia was analyzed using the World's Air Pollution resource. Statistical data and the results of a survey of the population on the causes of air pollution in the cities of their residence and measures to improve it were used; the publications of Russian and Chinese authors. As a general approach to address this issue, it is proposed to switch to electric public transport, including electric buses; restriction on trips by private vehicles to certain areas of cities; restriction on the entry of commercial vehicles during the hours of the greatest traffic. The Chinese authors propose a ban the sale of cars. Russian scientists have substantiated the idea of the influence of building density on the dispersion of polluted air.

Indirect neural-based finite-time integral sliding mode control for trajectory tracking guidance of Mars entry vehicle

This article presents an indirect neural-based finite-time integral sliding mode control algorithm for the reference trajectory tracking guidance of Mars entry vehicle under uncertainties. The proposed controller is developed as a combination of finite-time integral sliding mode controller and indirect neural identification. The finite-time integral sliding mode controller is designed by constructing a new type of finite-time integral sliding mode surface to prevent the singularity problem. Moreover, the neural network (NN) is combined with the finite-time integral sliding mode controller to identify the lumped uncertainty and attenuate the chattering phenomenon. Particularly, the concept of indirect neural identification is adopted and only a single adaptive parameter is required to be learned online. In this way, the proposed controller is not only strongly robust against aerodynamic and density uncertainties, but also computationally simple for onboard implementations. Stability argument indicates that the proposed controller can ensure the radial distance tracking error and its time differentiation regulate to the small residual sets around zero in finite time. Lastly, the effectiveness and excellent guidance performance of the proposed control algorithm are demonstrated through simulation studies on a Mars Science Laboratory-type (MSL-type) entry vehicle.

Study on Impact Load and Head Cap Load Reduction Performance of Vehicle Entering Water at High Speed

Aiming at the problem of high-speed entry of vehicles with a diameter of 200 mm, a numerical model of high-speed entry of vehicles is established based on the arbitrary Lagrange–Euler (ALE) algorithm, and the numerical simulation of high-speed entry of flat-nosed and round-nosed vehicles is carried out. On this basis, the experimental research on the entry of vehicle with buffer caps is carried out. The following conclusions are obtained through simulation. The peak value of the axial load of the vehicle raises with the increase of the inlet velocity and angle, while the stable value only raises with the increase of the inlet velocity. The impact load on the round-nosed vehicle is obviously smaller than that on the flat-nosed vehicle when the water entry angle is greater than 80°. The peak value of axial load can be reduced by 22% when entering water vertically at 100 m/s. The following conclusions are obtained through experiments. The buffer head cap has a significant load reduction effect. It shows compaction, cracks and breakage under the impact of water. These processes can absorb part of the impact energy, reduce the peak value of axial load and increase the pulse width. The load reduction rate grows from 4.7% to 18.5% when the length of the buffer head cap is increased from 200 mm to 300 mm while the water inlet speed is the same. The damage level of the head cap increases sharply, and the load reduction rate raises when the water entry speed is increased while the length of the buffer head cap is the same.

Research on RCS Jet Interaction Characteristics of the Capsule Entry Vehicle at Subsonic and Transonic Speed

In this paper, the RCS jet interaction characteristics of the capsule entry vehicle were studied by numerical simulation. The jet interference characteristics under different re-entry ballistic parameters were compared. The influence of the angle of attack on the jet flow field structure and aerodynamic characteristics was analyzed.

ANALISIS KINERJA RUAS JALAN KELAPA 2 ENTROP JAYAPURA

Roads are a very important means of land transportation for people to connect one area to another. It also functions and plays a role in improving the regional economy, it is also needed for transportation activities to facilitate the safe and comfortable movement of goods and services. One of the factors is Jalan Kelapa 2 Entrop being the busiest road in Jayapura City because this road is a connecting road for the people of Keerom Regency and Jayapura City. The author conducted research by direct observation to the field and retrieved the data needed to support the research such as intersection geometry conditions, traffic volume, speed and side resistance. The data was then processed and analyzed using the 1997 Indonesian Highway Capacity Manual method. The research was carried out by observing for three days and carried out in the morning, afternoon and evening according to traffic congestion conditions. Based on the calculation results, a solution or alternative is obtained, namely prohibiting the entry and exit of vehicles on the side of the road and imposing a ban on parking on the east side of the road, also obtaining a road capacity value of 1312.84 pcu/hour, DS of 0.76 and FV 28.18 km/ hours, so that the degree of saturation is 0.76, so it still meets the normal limit requirements based on the 1997 Indonesian Road Capacity Manual.

Mars Entry, Descent, and Landing Instrumentation 2 Trajectory, Aerodynamics, and Atmosphere Reconstruction

On February 18th, 2021, the Mars 2020 entry system successfully delivered the Perseverance rover to the surface of Mars at Jezero Crater. The entry capsule carried a set of instrumentation installed on the heat shield and backshell, named the “Mars Entry, Descent, and Landing Instrumentation 2.” The instruments include pressure transducers, thermocouples, heat flux gauges, and radiometers to measure the aerodynamic and aerothermodynamic performance of the entry vehicle. This paper describes the trajectory and atmosphere reconstruction results based on the pressure sensor measurements. The process uses a Kalman filter approach to estimate the freestream atmospheric properties from the pressure measurements combined with a model of the pressure distribution of the heatshield and other sensor inputs, including an inertial measurement unit and other on-board navigation sensors, and several external atmospheric observations. The results indicate that the upper altitude density was up to 150% higher than nominal, which is consistent with the observed early entry guidance start time. The density below 40 km was within 12% of the preflight predictions. The reconstructed axial force coefficient was approximately 2% lower than the preflight prediction across the flight range.

An Efficient MAC Protocol for Blockchain-Enabled Patient Monitoring in a Vehicular Network

Blockchain is an emerging computing platform that provides recording and tracking facilities to substantially increase the security issues in healthcare systems. The evolution of wireless body area networks requires the continuous monitoring of the health parameters of traveling patients while traveling on road. The health parameter data of each patient are sent to the Road Side Units (RSUs) for generating the blocks by computing the required hash functions. A major challenge in such a network is to efficiently exchange the data blocks between mining RSUs and vehicles using a medium access protocol with a reduced number of collisions. The medium access problem becomes more challenging due to the vehicle mobility, high vehicle density and the varying nature of the data generated by the vehicles. In this work, a TDMA-based MAC protocol to meet an Adaptive Patients Data traffic for Vehicular Network (TAPDVN) is proposed. TAPDVN is specifically designed for patients in a vehicular network by considering the frequent entry and exit of vehicles in a mining node’s coverage area. It allows mining nodes to adjust time slots according to the sensitive patient’s data and allows the maximum number of patient vehicular nodes by considering their sensitivity to send their data in a session to compute their hash values accordingly. Simulation results verify that the proposed scheme accommodates the maximum number of high-risk patient data and improves bandwidth utilization by 20%.

TRAPSim: An agent-based model to estimate personal exposure to non-exhaust road emissions in central Seoul

Non-exhaust emissions (NEEs) from brake and tyre wear cause detrimental health effects, yet their relationship with mobility has not been examined rigorously. We constructed an agent-based traffic simulator to illustrate the coupled problems of emissions, behaviour, and the estimated exposure to PM10 for groups of drivers and subway commuters in Seoul CBD. Having calibrated the parameters, the results regarding the air quality revealed that roughly 25–30% of the roadside PM10 was significantly higher than the background PM10. Additionally, compared to intra-urban cars, pedestrians who commuted for longer periods of time and were exposed to more ambient particles suffered significant health losses; however, drivers only became aware of the health risk when PM10 levels were consistently high for a few days. Compared to the business-as-usual scenario of vehicle entry, a 90% vehicle restriction was able to reduce PM10 by 18–24% and cut the percentage of resident drivers who were at risk. However, it was not effective for subway commuters. Using an agent-based traffic simulator in a health context can provide insights into how exposure and health effects can vary depending on the time of exposure and the form of transportation.

Study on the Development of Multi-Purpose Fire Engines through Vehicle Safety Factor Design

With the recent rapid economic growth, the construction of high-rise buildings such as new town apartment complexes, residential-commercial complexes, and office buildings has increased. This study thus attempted to develop a multi-purpose fire engine to enhance the response to a fire and rescue efforts in line with the steady increase in the demand for safety in high-rise buildings, through a design that combined techniques that focused on large ladders and a midsized 5-ton fire pump engine. A ladder function was added to the most widely used fire engine, with the design incorporating a maximum ladder height of 20 m for fire suppression and lifesaving. A basket was fitted to the end of the ladder to enable firefighters to safely perform these tasks, while the outrigger was designed to vertically descend to allow ladder work as long as vehicle entry is possible despite illegally parked cars. Based on the chassis of a commercial 5-ton fire engine as a type of conventional midsized pump engine, the result was a multi-purpose fire engine developed for special uses that require both fire pump and ladder functions. The multi-purpose fire engine was designed in consideration of safety factors for the direct rescue of people from buildings using a basket rated for a maximum load of 250 kg, through the application of a boom in addition to the common fire pump. It is expected that after their rapid arrival at the scene of a fire, such multi-purpose fire engines could be used for firefighting or lifesaving at relatively low 2-6-story buildings. It is anticipated that the present investigation and other relevant studies will allow the application of this novel design to various other vehicle types such as water tanks, chemical tanks, and rescue vehicles.

The Effect of Roll Rate on Simulated Entry Vehicle Ballistic Range Tests

Free-flight computational fluid/rigid-body dynamics simulations are now being explored as a way to augment physical experiments for characterizing the dynamic behavior of blunt-body atmospheric entry vehicles. Initializing these simulations with accurate initial conditions is critical to achieving validation against experimental results and characterizing vehicle behavior. This paper explores the impact of a nonnegligible initial roll rate on numerical free-flight simulations of ballistic range tests using the FUN3D Navier–Stokes flow solver and POST2 trajectory propagator. These ballistic range shots were performed on a model of the Supersonic Inflatable Aerodynamic Decelerator at the NASA Ames Hypervelocity Free-Flight Aerodynamics Facility. In the absence of measured roll data, a method for reconstructing the initial roll rate is developed assuming that a nonnegligible roll rate accounts for the exchange in amplitude between the experimental pitch and yaw data. Simulations of three shots spanning a range of initial roll rates are executed to evaluate the new method. Results are validated against the physical ballistic range tests. Simulations with the reconstructed roll rate are more accurate to the experimental data than those assuming a negligible initial roll rate. Direct calculation of the pitch damping coefficient also captures the effect of roll rate on pitching moment.

The influence of shock speed variation on radiation and thermochemistry experiments in shock tubes

Shock tubes are a crucial source of experimental data for the aerothermodynamic modelling of atmospheric entry vehicles. Notably, many chemical-kinetic and radiative models are validated directly against optical measurements from these facilities. Typically, the incident shock speed at the location of the experimental measurement is taken to be representative of the test slug; however, the shock velocity can vary substantially upstream of this location. These variations have been long posited as a source of disagreement with computational predictions, although a definitive link has proved elusive. This work describes a series of experiments which aim to isolate and confirm the importance of the shock deceleration effect. This is achieved by generating different shock trajectories and comparing the post-shock trends in atomic oxygen emission and electron density. These trends are shown to be directly linked to the upstream shock speed variations using a recently developed numerical tool (LASTA). The close agreement of the comparisons confirms the importance of shock speed variation for shock tube experiments; these findings have direct and potentially critical relevance for all such studies, both past and present.

The Magnetization of an Underwater Caldera: A Time‐Lapse Magnetic Anomaly Study of Axial Seamount

AbstractAxial Seamount in the northeast Pacific erupted in 2015, 2011, and 1998. Although monitored by the Regional Cabled Array of the Ocean Observatory Initiative, few magnetic surveys have been conducted over the region. This study uses high‐resolution magnetic data over the seamount collected by autonomous underwater vehicle Sentry during three years (2015, 2017, and 2020). The goal is to investigate whether there are temporal changes in the near‐surface magnetic field observable over the time scale of one volcanic cycle. We compare magnetic maps from repeated tracklines from each year. We find maps of the yearly difference in magnetization show coherent patterns that are not random. The central region of the caldera has become more magnetic during recent years, suggesting cooling of the surficial lava flows since 2015. Sentry data are more sensitive to shallow crustal structure compared to sea surface data which show longer wavelength anomalies extending deeper into the crust.

Relative Timing of Off‐Axis Volcanism From Sediment Thickness Estimates on the 8°20’N Seamount Chain, East Pacific Rise

AbstractVolcanic seamount chains on the flanks of mid‐ocean ridges record variability in magmatic processes associated with mantle melting over several millions of years. However, the relative timing of magmatism on individual seamounts along a chain can be difficult to estimate without in situ sampling and is further hampered by Ar40/Ar39 dating limitations. The 8°20’N seamount chain extends ∼170 km west from the fast‐spreading East Pacific Rise (EPR), north of and parallel to the western Siqueiros fracture zone. Here, we use multibeam bathymetric data to investigate relationships between abyssal hill formation and seamount volcanism, transform fault slip, and tectonic rotation. Near‐bottom compressed high‐intensity radiated pulse, bathymetric, and sidescan sonar data collected with the autonomous underwater vehicle Sentry are used to test the hypothesis that seamount volcanism is age‐progressive along the seamount chain. Although sediment on seamount flanks is likely to be reworked by gravitational mass‐wasting and current activity, bathymetric relief and Sentry vehicle heading analysis suggest that sedimentary accumulations on seamount summits are likely to be relatively pristine. Sediment thickness on the seamounts' summits does not increase linearly with nominal crustal age, as would be predicted if seamounts were constructed proximal to the EPR axis and then aged as the lithosphere cooled and subsided away from the ridge. The thickest sediments are found at the center of the chain, implying the most ancient volcanism there, rather than on seamounts furthest from the EPR. The nonlinear sediment thickness along the 8°20’N seamounts suggests that volcanism can persist off‐axis for several million years.

Linear Pseudospectral Entry Guidance Algorithm Using Differential Flat Output for High Lift-to-Drag Ratio Entry Vehicle

Linear Pseudospectral Entry Guidance Algorithm Using Differential Flat Output for High Lift-to-Drag Ratio Entry Vehicle