ALHAT System Architecture and Operational Concept

Brady, Tye; Schwartz, Jana L.

doi:10.1109/aero.2007.352725

Cited by 29 publications

(18 citation statements)

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“…The TSAR package mimicked a 30° trajectory approach to those terrains during which overlapping flashes were collected, starting at 750m slant range, and a Lidar DEM was generated from them. The sensor flashes were simulated using a high-fidelity flash Lidar model provided by NASA Langley Research Center [3]. A Lidar with 256x256 detector and 1° FOV, mounted on a gimbal platform, was assumed.…”

Section: Resultsmentioning

confidence: 99%

“…More recently, technologies for automated detection of rocks and craters from EO imagery were selected by NASA's New Millennium program but a funding shortfall precluded further development [18,31,32]. A recent study recommended active sensing as the best choice for a lunar mission due to its ability to work under any sun illumination [3]. In 2007, the ALHAT project began an end-to-end technology development, including HDA, using a Lidar [11].…”

Section: Previous Workmentioning

confidence: 99%

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Probabilistic Hazard Detection for Autonomous Safe Landing

Ivanov

Huertas

Carson

2013

AIAA Guidance, Navigation, and Control (GNC) Conference

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Future generation of landing craft will autonomously look at the surface during the terminal phase of powered descent and then, in real-time, choose and divert to a safe landing site in order to avoid hazards. Enabling technologies for such capability have been under development in recent years in the Autonomous Landing Hazard Avoidance Technology (ALHAT) project funded by NASA's Exploration Technology Development Program.ALHAT is a comprehensive system that spans the approach and landing events -from de-orbit coasting to touchdown. In this paper, we focus on ALHAT's perception task of detecting hazards in the sensed terrain and of selecting candidate safe sites for landing. This task, named Hazard Detection and Avoidance (HDA), occurs in the middle of the landing sequence. Our approach to HDA employs a probabilistic model in order to better manage the ubiquitous uncertainties associated with noisy sensor measurements and navigation. Also, we explicitly take into account the geometry of the lander and its interaction with the surface when assessing hazards. Experimental results on synthetic Lunar-like terrain show that our HDA algorithm can designate safe landing locations for a variety of terrain types and density and abundance of hazards. The complete ALHAT system is undergoing ground field-testing, and is scheduled for additional field tests on a one-hectare, lunar-like, hazard field recently constructed at NASA's Kennedy Space Center (KSC). Although the focus of ALHAT is on autonomous planetary landings, a number of terrestrial applications can also benefit from out HDA system.

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Section: Resultsmentioning

confidence: 99%

Section: Previous Workmentioning

confidence: 99%

Probabilistic Hazard Detection for Autonomous Safe Landing

Ivanov

Huertas

Carson

2013

AIAA Guidance, Navigation, and Control (GNC) Conference

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“…A fuel-optimized approach/landing trajectory (i.e., fast and low, or shallow perspective, with the velocity being arrested just before touchdown) to the lunar surface was used to generate the Small OTW view condition. This type of trajectory is being considered for the Altair lunar missions [8]. An Apollo-like approach/landing trajectory was used to generate the Large OTW view condition.…”

Section: Independent Variable -Out the Window Vertical Field-of-regardmentioning

confidence: 99%

“…Preliminary concepts and operations [8][9] anticipated for the Altair Lunar Lander are contradicting Apollo's experience in the use of a pilot's natural vision as the primary landing aid. First, preliminary design concepts for a Lunar Lander show significantly less external visibility for the astronauts than that provided to the Apollo astronauts.…”

Section: Introductionmentioning

confidence: 99%

Effects of synthetic and enhanced vision technologies for lunar landings

Kramer

Prinzel

Bailey

et al. 2009

2009 IEEE/AIAA 28th Digital Avionics Systems Conference

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Eight pilots participated as test subjects in a fixedbased simulation experiment to evaluate advanced vision display technologies such as Enhanced Vision (EV) and Synthetic Vision (SV) for providing terrain imagery on flight displays in a Lunar Lander Vehicle. Subjects were asked to fly 20 approaches to the Apollo 15 lunar landing site with four different display concepts -Baseline (symbology only with no terrain imagery), EV only (terrain imagery from Forward Looking InfraRed, or FLIR, and LIght Detection and Ranging, or LIDAR, sensors), SV only (terrain imagery from onboard database), and Fused EV and SV concepts. As expected, manual landing performance was excellent (within a meter of landing site center) and not affected by the inclusion of EV or SV terrain imagery on the Lunar Lander flight displays. Subjective ratings revealed significant situation awareness improvements with the concepts employing EV and/or SV terrain imagery compared to the Baseline condition that had no terrain imagery. In addition, display concepts employing EV imagery (compared to the SV and Baseline concepts which had none) were significantly better for pilot detection of intentional but unannounced navigation failures since this imagery provided an intuitive and obvious visual methodology to monitor the validity of the navigation solution.

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“…To improve the accuracy of the landing, new navigation systems have been developed over the years. Such is the case of Magnolia-1, a robust algorithm for autonomous hazard detection and avoidance (HDA) that requires no input from classical inertial sensors, since the hazard assessment and navigation is done by using imaging camera [9]. Hypersonic guidance has also been studied as an option.…”

Section: Introductionmentioning

confidence: 99%

Use of Modern Digital Software to Model the Motion Dynamics of Spacecraft during Landing

Koryanov

Heras

2020

ITM Web Conf.

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Landing systems for future space missions in Earth and Mars require trustable technologies capable of achieving their aim in the most accurate way possible. For this purpose, systems should go through rigorous dynamic simulations run by precise and efficient software. This study aims to approximately determine the dynamic motion of a landing vehicle using the modern digital software of Universal Mechanism and MATLAB. Universal Mechanism applies the classic mechanics theory on a model based on the geometry of the spacecraft, taking into account the environmental conditions that affect its motion and the properties of the ground to resist its impact [1]. The forces implied in the vehicle phase of descent are also included in MATLAB code to calculate the landing area of the vehicle according to its re-entry velocity [2-4]. Studies were conducted for different initial conditions and approaches to the surface. As a result, the values of the arising overloads and forces acting on the descent vehicle were obtained [1]. The data provided by the simulations conclude the safest landing options that should be taken into account for the success of future missions.

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ALHAT System Architecture and Operational Concept

Cited by 29 publications

References 0 publications

Probabilistic Hazard Detection for Autonomous Safe Landing

Probabilistic Hazard Detection for Autonomous Safe Landing

Effects of synthetic and enhanced vision technologies for lunar landings

Use of Modern Digital Software to Model the Motion Dynamics of Spacecraft during Landing

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