Actual Landing Research Articles

First rocks sampled in Antarctica (1840): Insights into the landing area and the Terre Adélie craton

In January 1840, Dumont d’Urville's expedition landed along the coast of “Terre Adélie” and took three rock specimens, the first ever sampled on the Antarctic continent. The petrological and geochemical study of these samples, stored at the “Muséum national d’histoire naturelle”, in Paris, characterizes them as migmatitic cordierite+microcline-bearing paragneiss and mesocratic quartz+biotite-bearing amphibolite. The paragneiss reached 670°C at 3.2 kbar, suggesting an abnormal high-T gradient of ca. 60°C/km during the regional metamorphism that affected the “Terre Adélie” craton 1.7Ga ago. The studied samples are identical to the rocks observed at the “Rocher du Débarquement”, confirming that this was the actual landing place. On the other hand, quartz diorite and volcanic rocks reportedly sampled in Adélie Land during the same expedition and stored at Le Mans and Toulouse Museums do not originate from Antarctica. The examination of Dumont d’Urville's map suggests an icecap shrinking by 9 km in the landing area since 1840.

Designation and Control of Landing Points for Competitive Robotic Table Tennis

Competitive robotic table tennis involves many topics such as smart ball returning strategy, precise motion control, etc. It remains a quite challenging task due to the unpredictable, uncooperative incoming ball and the requirement of a smart strategy to defeat the opponent. Designation and control of landing points is one basic aspect of ball returning strategies in competitive robotic table tennis because different landing points require the opponent to make different efforts to return the ball. In this paper, we present a method to designate desired landing points based on competitiveness level. We also propose a learning based landing point control approach to minimize the error of the actual landing points with respect to the designated landing points. The proposed methods have been verified through experiments on a humanoid table tennis robot.

Ground-Based Videometric Method and System for the Real-Time Measurement of Aircraft Landing Track

This paper proposes a ground-based videometric method and system for measuring the glide track of landing aircraft in real time. The proposed method is applicable for large-scale measurement via regional relays with multiple cameras. Its measurement ranges from kilometers away to the landing point, and it simultaneously fulfills the real-time measurement of the position and trajectory of aircraft. The real-time measurement result of the actual aircraft landing process shows a deviation from DGPS(Difference Global Positioning System) as small as 20 cm in the measuring region of 1 km. The proposed measurement method for aircraft landing track based on videometrics can establish a new type of landing aid system removed from radar and GPS.

Mars Science Laboratory Flyaway Guidance, Navigation, and Control System Design

This paper describes the flyaway guidance, navigation, and control system design that was successfully used during the landing of NASA’s Mars Science Laboratory on Mars on 5 August 2012. One of the most challenging phases of the Mars Science Laboratory mission is the entry, descent, and landing that starts with the Mars atmospheric entry and ends with the rover Curiosity landing on Mars and the descent stage with the sky crane crashing to the surface. Because the two-way signal’s communication time between Earth and Mars is about 26 min and the fact that the end-to-end entry, descent, and landing takes about 7 min, the lander must be controlled completely autonomously. At the last step of the landing, the rover is lowered to the surface by using a new sky crane, which resides on the descent stage of the lander. The sky crane slowly descends toward the Martian surface as the rover is lowered. Once the touchdown is detected, the onboard control system flies the descent stage as far away as possible from the rover. This phase of the landing is called the “flyaway.” The flyaway is the last phase, and its main goals are to move the sky crane, which may contain unused propellant, to a safe distance and to avoid plume impingement on the sensitive science instruments on the rover during the flyaway maneuver. The coupled attitude and translational motion is planned, that is, rotational and translational trajectories are time profiled by the onboard guidance algorithm. The trajectories obey the control authority constraints, due to maximum torque and force, while maximizing the divert distance. These guidance trajectories are tracked by using feedback control laws that provide robustness to any model uncertainties and disturbances forces and torques. Simulation results predicted that a desirable performance would be achieved in terms of the flyaway distance and the plume avoidance. Finally, the actual landing on Mars on 5 August 2012 was extremely successful, and the results were consistent with predictions.

Adding Active Learning to LWR for Ping-Pong Playing Robot

In this brief, we consider the problem of controlling the racket attached to the ping-pong playing robot, so that the incoming ball is returned to a desired position. The maps that are used to calculate the racket's initial parameters are described. They are implemented with the locally weighted regression (LWR). An active learning approach based on the fuzzy cerebellar model articulation controller (FCMAC) is proposed, and then it is added to the LWR, which is regarded as lazy learning. A learning algorithm that is used for updating the experience data in the fuzzy CMAC according to the errors between the actual and desired landing positions is presented. A series of experiments has been performed to demonstrate the applicability of the proposed method.

항공기 착륙거리의 여유분 산정에 관한 연구

운항의 여러 단계 중 착륙단계에서 조종사들이 많은 부담을 느낀다. 이는 조종사들이 항공기 속도를 줄이고 접지하여 완전히 정지하는 동안 착륙안전에 영향을 미치는 여러 요소가 있기 때문이다. 만일 착륙하는데 활주로길이가 충분하다면 부담이 적을 수도 있다. 그러나 항상 그런 경우만 있는 것은 아니다. 따라서 착륙성능이 제한범위 내에 있는지 아닌지를 확인할 필요가 있다. 필요착륙거리는 시험비행 조종사에 의해 실증되어진 실제착륙거리에다가 항공사의 평균적인 조종사들을 위한 여유분을 포함한 것이다. FAR의 AFM(항공기 비행규정) 인가는 건조 및 습윤 활주로에서 수동착륙을 기반으로 한다. 기타 다른 활주로 조건에서는 인가가 필요하지 않다. JAR에서는 빙설/윤활활주로에서도 정해진 여유분을 포함시키도록 규정하고 있다. 자동착륙은 인가사항이 아니므로 실제착륙거리만 제공된다. 본 논문에서는 각 활주로 조건에서 포함된 거리 여유분을 분석하고자 한다. 또한 특정한 활주로 조건에서 여유분이 규정되어 있지 않은 경우 대안을 제시하고자 한다. Among the phases of flight operations pilots feel much pressure in landing segment. There is a number of factors affecting landing safety while pilots reduce aircraft speeds and make a touchdown and stop completely. If runway length is sufficient for landing, there maybe is no problem. But it is not the case all the time. So it is necessary to confirm whether landing performance is within limits or not. Required landing distance is actual landing distance demonstrated by flight test pilot plus allowances for average airline pilots. FAR(Federal Aviation Regulations) AFM certification is based upon manual landing for dry and wet runway. Other runway conditions are not the certification basis. JAR dictates even contaminated/slippery runway is included by prescribed allowances. Automatic landing is not certification basis, so actual landing distances are provided. In this paper I would like to analyze distance allowances included in each type of runway condition. In addition there is no regulation about allowances for specific runway condition, I would suggest adequate allowances for that case.

Aircraft landing problems with aircraft classes

This article focuses on the aircraft landing problem that is to assign landing times to aircraft approaching the airport under consideration. Each aircraft's landing time must be in a time interval encompassing a target landing time. If the actual landing time deviates from the target landing time additional costs occur which depend on the amount of earliness and lateness, respectively. The objective is to minimize overall cost. We consider the set of aircraft being partitioned into aircraft classes such that two aircraft of the same class are equal with respect to wake turbulence. We develop algorithms to solve the corresponding problem. Analyzing the worst case run-time behavior, we show that our algorithms run in polynomial time for fairly general cases of the problem. Moreover, we present integer programming models. We show by means of a computational study how optimality properties can be used to increase efficiency of standard solvers.

Landing Performance Optimization Algorithm of Civil Aircrafts

This paper explains and demonstrates how to calculate and optimize landing performance. According regulation requirement, it needs to consider the different requirements [1], including landing field length, missed approach climb gradient, brake energy and tire speed. Weights limited by the different requirements are calculated, the minimum of these weights limited are determined as the actual allowed maximum landing weight.

Developmental Changes of Misconception and Misperception of Projectiles

This study investigated the developmental changes of perceptual and cognitive commonsense physical knowledge. Children 4 to 9 years old (N = 156; 79 boys, 77 girls) participated. Each child was asked to predict the landing positions of balls that rolled down and fell off a virtual ramp and to choose the most natural-looking motion from different projectile motions depicted. The landing position of the most natural-looking projectile was compared with the predicted landing position and also compared with the actual landing position. The results showed children predicted the ball's landing position closer to the ramp than the actual position. Children also chose the depiction in which the ball fell closer to the ramp than the accurate position, although the error in the prediction task was larger than in the perception task and decreased with age. The results indicated the developmental convergence of explicit reasoning and implicit perception, which suggest a single knowledge system with representational re-description.

Entry, Descent, and Landing Performance of the Mars Phoenix Lander

On May 25, 2008, the Mars Phoenix Lander successfully landed on the northern arctic plains of Mars. An overview of a preliminary reconstruction analysis performed on each en-try, descent, and landing phase to assess the performance of Phoenix as it descended is pre-sented and a comparison to pre-entry predictions is provided. The landing occurred 21 km further downrange than the predicted landing location. Analysis of the flight data revealed that the primary cause of Phoenix’s downrange landing was a higher trim total angle of at-tack during the hypersonic phase of the entry, which resulted in Phoenix flying a slightly lift-ing trajectory. The cause of this higher trim attitude is not known at this time. Parachute deployment was 6.4 s later than prediction. This later deployment time was within the varia-tions expected and is consistent with a lifting trajectory. The parachute deployment and in-flation process occurred as expected with no anomalies identified. The subsequent parachute descent and powered terminal landing also behaved as expected. A preliminary reconstruc-tion of the landing day atmospheric density profile was found to be lower than the best apri-ori prediction, ranging from a few percent less to a maximum of 8%. A comparison of the flight reconstructed trajectory parameters shows that the actual Phoenix entry, descent, and landing was close to pre-entry predictions. This reconstruction investigation is currently on-going and the results to date are in the process of being refined.

Landing-Site Dispersion Analysis and Statistical Assessment for the Mars Phoenix Lander

Landing-Site Dispersion Analysis and Statistical Assessment for the Mars Phoenix Lander

Jumper Kinematics on Terrain Park Jumps: Relationship between Takeoff Speed and Distance Traveled

Abstract The performance of individuals jumping tabletop features in terrain parks has not been widely studied. A field study was conducted to measure the takeoff speed and horizontal distance achieved by jumpers at two tabletop style jump features: A smaller jump at Snow Summit, CA and a larger jump at Mammoth Mountain, CA, USA. Analyses were also conducted to determine the effects of equipment type (skis versus snowboard) on jumper kinematics. Before each data collection session, the physical dimensions of the jump were measured and recorded. For consecutive jumpers, the speed parallel to the ramp was measured at the end of the takeoff by using a laser speed trap accurate to 0.11 m/s. The landing zone was marked at 3.0 m intervals with colored dye, beginning just past the flat deck portion of the jump. A high-definition video camera was used to record the landing of each jumper, and the landing point of the projected center of mass was determined by using photogrammetry, accurate to within 5 cm. The actual landing distances measured in the field were compared to predicted landing distances by using ordinary ballistic equations. A total of 280 jumps was observed on the two features: 105 on skis and 175 on snowboards. The correlation coefficients between the square of the takeoff speed and the landing distance for the smaller and larger jumps were 0.75 (R2=0.56) and 0.41 (R2=0.16), respectively. The measured landing distances differed significantly from those predicted by models using the ballistic equations of motion. The average landing distance beyond the knuckle was 2.4 m on the smaller jump and 2.1 m on the larger jump. For both features, skier and snowboarder jumpers did not differ in average landing distance.

Mars Surface Exploration Caching from an Orbiting Logistics Depot

E XPLORATION missions on Earth have used the principle of caching for centuries. Caching involves prepositioning discrete quantities of supplies at specific locations along a route in order to lighten the burden or extend the range of an exploring party. Historical missions that made use of caching on Earth are the Lewis and Clark expedition in 1803–1806 [1] and the ill-fated Imperial Trans-Antarctic Expedition of 1914–1917 [2]. Caching may play an important role in the future of manned planetary exploration as well. Without it, exploration sorties are inherently limited to a specific distance from a base or landing location given by the type of transportation vehicles used, the size of the crew, the mix and quantity of consumables, operational rules, and the nature of the terrain. For manned lunar missions, for example, this distance has been estimated at 3 km for exploration on foot, 5–15 km with unpressurized rovers, and up to 30 kmwith pressurized rovers [3]. In part, exploration range is determined by the quantity of consumables that can be carried along, limiting the amount of useful exploration that can be done at distances greater than 30 km from the landing site or base. Similar issues exist for manned Mars exploration. This Note explores the concept of storing caches in a logistics depot on orbit and deliberately deploying them to the surface to extend human exploration range.Wewill useMars as the motivating context, but the idea may apply to other situations as well. We first introduce the concept and then perform initial sizing of such a depot. This Note does not explore the full tradespace of orbital depots and caching architectures. Caching in space exploration can be implemented as two different architectures: direct entry from inspace trajectory and orbital entry from a low Mars orbit. While the direct entry does not contain the Martian orbit insertion maneuver and can be more efficient in terms of required V, this Note only considers the orbital entry because of the following two reasons. First, the short time gap between deployment decision and actual landing of the supply unit provides meaningful flexibility to operate on orbit. Secondly, advanced propulsion systems such as a nuclear electric propulsion system (NEP) and solar electric propulsion can significantly reduce the cost resulting from the orbit insertion, and the efficiency gap gets very small. Let us consider an orbiting logistics depot that is composed of a cluster of supply units deployed to aMartian orbit. Each prepackaged supply unit contains supply items (fuel and consumables) that allow extending the range of humans exploring the surface of Mars. Figure 1 shows the orbiting depot concept and its concept of operations. Typically, one or more surface vehicles start exploration from a base and return to the base before all fuel and consumables (e.g., fuel, food, water, and oxygen) have been expended. This is the case of an unassisted surface route, yielding a total distanceD. In this case, the amount of fuel and consumables that can be used during a single route is determined by the capacity of the surface exploration vehicle. Now suppose that there is a logistics depot in Martian orbit and it is possible to command the depot to drop a supply unit (pod) filled with a known mix and quantity of consumables corresponding approximately to a vehicle’s capacity. If the supply unit lands at such a location that the surface exploration vehicle can reach the unit before it runs out of consumables, the vehicle’s range can effectively be doubled to 2D. This is the case of the depot-assisted surface route shown in Fig. 1 (right) along with a simulated pod landing error ellipse. In the following sections we discuss the most important design decisions for such an orbiting depot, including orbit selection, individual supply unit design, and depot operations. These calculations are meant to establish a realistic “strawman” for the concept. Studies regarding detailed design in the context of specific surface exploration campaign strategies are left for future work.

Probabilistic modelling of the role of the human factor in the Helicopter-Landing-Ship (HLS) situation

This analysis contains a novel attempt to quantify, on the probabilistic basis, the role that the human factor plays, in terms of the total operation time, in the Helicopter-Landing-Ship (HLS) situation. The considered operation time includes the time required for the officer-on-ship-board and the helicopter pilot to make their go-ahead decisions, and the time needed for the actual landing. It is assumed, for the sake of simplicity, that these times could be approximated by the Rayleigh law, while the duration of the lull follows the normal (Gaussian) law. Safe landing can be expected if the probability that it takes place during the lull time in the sea condition is sufficiently high. We develop a simple, easy-to-use and physically meaningful model to evaluate this probability. Our model can be used in the risk analysis of the landing situation, as well as in the probabilistic assessment of the strength of the helicopter undercarriage, if necessary. The model can be employed also when developing guidelines for personnel training and particularly when there is a need (intent) to establish (specify) the acceptable (allowable) decision making time.

Helicopter Landing Ship: Undercarriage Strength and the Role of the Human Factor

We address, using probabilistic modeling and the extreme-value-distribution technique, the helicopter undercarriage strength in a helicopter-landing-ship situation. Our analysis contains an attempt to quantify, on the probabilistic basis, the role of the human factor in the situation in question. This factor is important from the standpoint of the operation time that affects the likelihood of safe landing during the lull period in the sea condition. The operation time includes (1) the time required for the officer-on-ship-board and the helicopter pilot to make their go-ahead decisions and (2) the time of actual landing. It is assumed, for the sake of simplicity, that both these times could be approximated by Rayleigh’s law, while the lull duration follows the normal law with a high enough ratio of the mean value to the standard deviation. Safe landing could be expected if the probability that it occurs during the lull time is sufficiently high. The probability that the helicopter undercarriage strength is not compromised can be evaluated as a product of the probability that landing indeed occurs during the lull time and the probability that the relative velocity of the helicopter undercarriage with respect to the ship’s deck at the moment of encounter does not exceed the allowable level. This level is supposed to be determined for the helicopter-landing-ground situation. The developed model can be used when developing specifications for the undercarriage strength, as well as guidelines for personnel training. Particularly, the model can be of help when establishing the times to be met by the two humans involved to make their go-ahead decisions for landing and to actually land the helicopter. Plenty of additional risk analyses (associated with the need to quantify various underlying uncertainties) and human psychology related efforts will be needed, of course, to make such guidelines practical.

Post-saccadic location judgments reveal remapping of saccade targets to non-foveal locations

The present study addresses the question of how objects are localized across saccades. In a task requiring participants to compare the location of a post-saccadic probe with the pre-saccadic target, we investigated the roles of saccade landing site and post-saccadic probe location. Saccade landing sites vary from trial to trial because of oculomotor error but can also be shifted by saccadic adaptation. Visual targets were extinguished during the saccade and reappeared after a short blank to counteract saccadic suppression of displacement. Performance in localizing targets after unadapted saccades was nearly veridical and independent of actual landing site, showing that trial-to-trial oculomotor error did not contribute to post-saccadic localization. This result suggests that much of the oculomotor error of saccades is included in the efference copy vector and this allows the recovery of a remapped target location that is often not foveal, but stable and accurate across trials. Displacement judgments relative to this remapped location will be independent of trial-to-trial variability in landing site. After adapted saccades, post-saccadic localization shifted in the direction opposite to adaptation but again, trial-by-trial landing site variability did not correlate with performance. This result suggests that the efference copy matches the planned upcoming saccade, be it adapted or not.

Mesoscale and large‐eddy simulation model studies of the Martian atmosphere in support of Phoenix

In late May of 2008, the NASA/JPL Phoenix spacecraft will touch down near its targeted landing site on Mars (68.2°N, 126.6°W). Entry, descent, and landing (EDL) occurs in the late afternoon (∼1630 hours local solar time (LST)) during late northern spring (Ls ∼ 78°). Using a mesoscale and a large‐eddy simulation (LES) model, we have investigated the range of conditions that might be encountered in the lower atmosphere during EDL. High‐resolution (∼18 km) results from the Oregon State University Mars MM5 (OSU MMM5) are used to understand the hazards from the transient circulations prominent during this season. Poleward of ∼80°N these storms produce strong winds (∼35 m s−1) near the ground; however, owing to the synoptic structure of these storms, and the deep convective mixed layer equatorward of the seasonal cap boundary during EDL, our modeling suggests the spacecraft would not be in winds stronger than ∼20 m s−1 at parachute separation. The storm‐driven variability is much weaker at Phoenix latitudes than it is poleward of the seasonal cap edge (result from an extensive sensitivity study). The OSU MLES model is used to explicitly simulate the hazards of convection and atmospheric turbulence at very high resolution (100 m). This modeling suggests that an upper bound for the maximum expected horizontal‐mean atmospheric turbulent kinetic energy (TKE) is ∼12 m2 s−2, seen ∼3 km above the ground at ∼1430 hours LST. TKE amplitudes are greatest when the horizontal mean wind is large (shear production) and/or the surface albedo is low (a lower albedo enhances buoyancy production, mimicking decreased atmospheric stability after a storm advects colder air into the region). LES simulations predict deep mixed layers (∼6–7 km), ∼1.5 km deeper than the mesoscale model (∼5 km). Mesoscale modeling suggests that the actual landing site differs meteorologically from other longitudes (larger‐amplitude diurnal wind cycle), a consequence of the strong thermal circulations that are excited by the very large regional topography. The OSU MLES model was modified for this work to utilize time‐ and height‐dependent geostrophic wind forcing (constructed from OSU MMM5 results). With this forcing, the OSU MLES provides a site‐specific simulation, where the time/height variability of the horizontal mean LES wind field is in good agreement with the OSU MMM5. On the basis of some statistical analysis, we have good confidence that the “full‐spectrum” wind field is within engineering guidelines for Phoenix EDL.

Age, growth, maturity, mortality, and yield-per-recruit for annular sea bream (Diplodus annularis L.) from the eastern middle Adriatic Sea

The population dynamics parameters of Diplodus annularis from the eastern middle Adriatic Sea were studied. Total lengths of 1704 specimens ranging from 3.3 to 23.0 cm were obtained from commercial and fishery-independent catches (2000–2002). The species spawns from April through the end of August, with a peak in May. Overall male to female ratio was 1.00 : 1.05. The species is a rudimentary hermaphrodite in the Adriatic Sea. Total lengths (TL) at 50% maturity were 9.0 cm for males and 10.0 cm for females. These estimated sizes were smaller than the minimum legal landing size (MLS = 15 cm) and greater than the actual minimum landing size (Lc = 7.1 cm) for the bottom trawl net. All specimens sampled were fully mature above 13 cm TL. The oldest individual was 13 years old. Length–weight relationship showed close to isometric growth (b = 3.073). Parameters of the von Bertalanffy growth equation were: L∞ = 23.95 cm; K = 0.126 per year; t0 = −1.664 year; r2 = 0.896. The low value of total mortality (Z = 0.72) was a consequence of the relatively low rate of natural mortality (M = 0.39) and fishing mortality (F = 0.33). The exploitation ratio was E = 0.46. Estimated parameters and the relative yield-per-recruit analysis did not indicate any overexploitation of the species in the study area. However, the estimates include uncertainties and require further confirmation, especially of the natural mortality.

Mars exploration rovers navigation results

The twin Mars Exploration Rovers, Spirit and Opportunity, were launched on June 10, 20033 and July 8, 2003, from Cape Canaveral, Florida. Spirit and Opportunity were targeted for landings at Gusev Crater (arrival on January 4, 2004) and Meridiani Planum (arrival on January 25, 2004). The primary navigation challenge was to deliver each spacecraft to the desired atmospheric entry interface point with sufficient accuracy such that each lander would touch down within a specified landing ellipse (about 70 km × 5 km) determined to be safe for landing and also judged to be scientifically interesting. In order to achieve landing within the target ellipse, precise control of the inertial entry flight path angle (FPA) at atmospheric entry was required. The maximum allowable errors in FPA following TCM-5 (trajectory correction maneuver #5) at Entry (E) — 2 days were ±0.12° (3σ) for Spirit and ±0.14° (3σ) for Opportunity. Achieving these entry delivery accuracies necessitated significant improvements to the interplanetary navigation system used for MER. These improvements included new processes and software for orbit determination, propulsive maneuver design, and entry, descent, and landing (EDL) trajectory simulation. The actual achieved atmospheric entry accuracies for Spirit and Opportunity significantly exceeded the requirements. At the navigation data cutoff for the TCM-5 final design, the orbit determination FPA knowledge error was ±0.028° (3σ ) for Spirit and ±0.035° (3σ ) for Opportunity. Because of exceptionally accurate navigation performance, TCM-5 (E — 2 days) and TCM-6 (E — 4 hours) were canceled for both Spirit and Opportunity. The actual landing locations (determined from in-situ Doppler tracking between the MER rovers and the Mars Odyssey orbiter) differed from the target landing points by 10.1 km (downtrack) for Spirit and 24.6 km (downtrack) for Opportunity. The majority of the landing position offsets for both landers was primarily caused by variations in atmosphere and spacecraft aerodynamic modeling from what was predicted. The amount of the landing position offset caused by navigation-only errors was only 3.3 km (uptrack) for Spirit and 9.7 km (downtrack) for Opportunity.

Effect of Saccadic Adaptation on Localization of Visual Targets

Objects flashed briefly around the time of a saccadic eye movement are grossly mislocalized by human subjects, so they appear to be compressed toward the endpoint of the saccade. In this study, we investigate spatial localization during saccadic adaptation to examine whether the focus of compression tends toward the intended saccadic target or at the endpoint of the actual (adapted) movement. We report two major results. First, that peri-saccadic focus of the compression did not occur at the site of the initial saccadic target, but tended toward the actual landing site of the saccade. Second, and more surprisingly, we observed a large long-term perceptual distortion of space, lasting for hundreds of milliseconds. This distortion did not occur over the whole visual field but was limited to a local region of visual space around the saccade target, suggesting that saccadic adaptation induces a visuo-topic remapping of space. The results imply that the mechanisms controlling saccadic adaptation also affect perception of space and point to a strong perceptual plasticity coordinated with the well-documented plasticity of the motor system.