Landing Errors Research Articles

Semi-analytic approximate time-optimal asteroid landing with dimensionality reduction shooting

Pinpoint landing on asteroid is very challenging due to the uncertainties of the gravitational field, which highlights the urgent need for autonomous landing algorithms under such uncertainties. Some well-known guidance algorithms, such as APDG and real-time convex programming, either ignore thrust boundary constraints or are severely time consuming. In addition, these algorithms have the same difficulty in analyzing landing errors due to model uncertainty propagation, making the reliability of the algorithms in actual landings questionable. To address these challenges, we propose a landing framework that combines model identification, trajectory analytical solution and closed-loop corrections to achieve near-optimal real-time landing control. Firstly, we simplified the landing scenario, focusing on reducing the dimension of shooting variables to enable rapid trajectory calculation. Secondly, we derived error propagation equations and established criteria for trajectory replanning based on landing error prediction. Finally, we validated our approach with practical examples of the Shoemaker probe landing on Eros 433. Through real-time landing error estimation, our proposed framework enables spacecraft to achieve near time-optimal land within a given error threshold.

Fuel-optimal powered descent guidance for lunar pinpoint landing using neural networks

This paper presents a Neural Networks (NNs) based approach to generate the fuel-optimal powered descent guidance for lunar pinpoint landing. According to Pontryagin’s Minimum Principle, the optimality conditions are first derived. To generate the dataset of optimal trajectories for training NNs, we formulate a parameterized system, which allows for generating each optimal trajectory by a simple propagation without using any optimization method. Then, a dataset containing the optimal state-thrust vector pairs can be readily collected. Since it is challenging for NNs to approximate a bang-bang (or discontinuous) type of optimal thrust magnitude, we introduce a regularisation function to the switching function so that the regularized switching function approximated by a simple NN can be used to represent the optimal thrust magnitude. Meanwhile, another two well-trained NNs are used to predict the thrust steering angle and the time of flight given a flight state. Finally, numerical simulations show that the proposed method is capable of generating the optimal guidance that steers the lunar lander to the desired landing site with acceptable landing errors.

Cognitive-Motor Dual-Task Performance of the Landing Error Scoring System.

The Landing Error Scoring System (LESS) is a common assessment used to determine biomechanical landing errors. However, this assessment is completed as a single motor task, which does not require additional attentional resources. It is unclear if the LESS can be used to detect cognitive-motor interference (i.e., dual-task cost) in biomechanical errors associated with lower extremity injury. To determine if the LESS is a suitable clinical assessment of dual-task performance in uninjured females and to evaluate whether specific landing criteria are more affected by an additional cognitive load than others. Observational Cross-Sectional Design. Setting: University research laboratory. Twenty uninjured, physically active females participated. Intervention(s): Participants performed the LESS under three different conditions: baseline landing with no cognitive distraction (Single), a visual-based dual-task (Visual), and a number-based dual-task (Number). Mean sagittal, frontal, and total LESS scores were compared between conditions using a one-way repeated measures analysis of variance with Tukey post hoc corrections. Cohen's d effect sizes with 95% confidence intervals were used to determine the magnitude of differences. The frequency of errors for each individual LESS item under the three conditions were compared using Chi-Squared analyses. Participants exhibited greater sagittal plane (P=.013, d=0.91 [0.26, 1.56]) and total (P=.008, d=1.03 [0.37, 1.69]) errors during the Visual condition compared to the Single condition. Frontal plane errors were significantly greater during the Number condition compared to the Single condition (P=.008, d=1.03 [0.37, 1.69]). The frequency of errors observed for each LESS item did not statistically differ between conditions (all P>.05). The LESS was able to detect a dual-task cost in landing errors during both the Visual and Number conditions. We recommend developing clinically-oriented solutions to incorporate similar dual- task paradigms in traditional injury risk reduction programs.

Effect of Footwear Versus Barefoot on Double-Leg Jump-Landing and Jump Height Measures: A Randomized Cross-Over Study.

Assessing individuals in their own athletic footwear in clinics is common, but can affect movement, performance, and clinical measures. The aim was to compare overall Landing Error Scoring System (LESS) scores, injury risk categorization, specific LESS errors, and jump heights between habitual athletic footwear and barefoot conditions. Randomized cross-over laboratory study. Eighty healthy individuals (55% male) completed the LESS following standard procedures (i.e., land from a 30-cm box to a distance of 50% of body height and then jump upwards maximally). Participants performed the LESS three times in two randomized conditions: footwear and barefoot. LESS data were extracted from 2D videos to compare group-level mean LESS scores, group-level and individual-level injury risk categorization (5-error threshold), specific landing errors, and jump heights between conditions. LESS scores were significantly greater (0.3 errors, p=0.022) and jump heights were significantly lower (0.6 cm, p=0.029) in footwear than barefoot, but differences were trivial (d = 0.18 and -0.07, respectively) and not clinically meaningful. Although the number of high injury-risk participants was not statistically different at a group level (p=1.000); 27 individuals (33.8%) exhibited a clinically meaningful difference between conditions of one error or more in LESS score, categorization was inconsistent for 16.3% of individuals, and four of the 17 landing errors significantly differed between conditions. At a group level, habitual athletic footwear does not meaningfully influence LESS scores, risk categorization, or jump height. At an individual level, footwear can meaningfully affect LESS scores, risk categorization, and alter landing strategies. Use of consistent protocol and footwear is advised for assessing movement patterns and injury risk from the LESS given the unknown predictive value of this test barefoot. Level 3.©The Author(s).

Ankle dorsiflexion range of motion and landing postures during a soccer-specific task.

Ankle dorsiflexion range of motion (DF-ROM) has been shown to be associated with poor landing posture. However, previously used tasks have been controlled, and it is unclear whether clinical measurements of the ankle DF-ROM, are associated with landing positions during sport-specific task. This study sought to determine the relationship between ankle DF-ROM and landing positions. Thirty male soccer players participated in this study. The ankle DF-ROM was measured by the weight bearing lunge test in degrees using a cell phone app (TiltMeter). Landing patterns were assessed during a soccer-specific task using landing error scoring system items using Kinovea software. Simple correlations were used to evaluate the relationships between ankle DF-ROM and landing error scores. Significant correlations were found between ankle DF-ROM and landing errors (r = -0.450, P = 0.006). A decreased ankle DF-ROM was associated with greater landing errors in a soccer specific situation. These results suggest that ankle DF-ROM may serve a useful clinical measure for identifying poor landing posture in the real-world environment. Therefore, assessment of ankle DF-ROM could be included in the screening process, which could help identify the cause of the faulty motion.

Mission Analysis for Landing on Pluto from a Fast, Hyperbolic Trajectory

The results of a Pluto landing analysis study for a fast, hyperbolic approach trajectory are presented by assuming the use of a novel entry, descent, and landing system called an enveloping aerodynamic decelerator. A landing site uncertainty analysis is performed for an 11 September 2040 arrival by means of a Monte Carlo simulation to map key trajectory, aerodynamic, system, and atmosphere uncertainties to landing zone errors. The estimated 3 landing error ellipse is about 430 by 190 km. The band of feasible landing sites is between 35°N and 10°S latitude on the surface of Pluto.

Effect of an overhead goal on landing error scoring system and jump height measures

ObjectivesCompare overall Landing Error Scoring System (LESS) scores, risk categorisation, specific LESS errors, and double-leg jump-landing jump heights between overhead goal and no goal conditions. DesignRandomised cross-over. SettingLaboratory. Participants76 (51% male). Main outcome measuresParticipants landed from a 30-cm box to 50% of their body height and immediately jumped vertically for maximum height. Participants completed three trials under two random-ordered conditions: with and without overhead goal. Group-level mean LESS scores, risk categorisation (5-error threshold), specific landing errors, and jump heights were compared between conditions. ResultsMean LESS scores were greater (0.3 errors, p < 0.001) with the overhead goal, but this small difference was not clinically meaningful. Similarly, although the number of high-risk participants was greater with the overhead goal (p = 0.039), the 9.2% difference was trivial. Participants jumped 2.7 cm higher with the overhead goal (p < 0.001) without affecting the occurrence of any specific LESS errors. DiscussionPerforming the LESS with an overhead goal enhances sport specificity and elicits greater vertical jump performances with minimal change in landing errors and injury-risk categorisation. Adding an overhead goal to LESS might enhance its suitability for injury risk screening, although the predictive value of LESS with an overhead goal needs confirmation.

Dynamic knee valgus in anterior cruciate ligament non-contact injury and reinjury in professional female athletes. Determinant or not?

Dynamic Knee Valgus (DKV) is correlated with both, Anterior Cruciate Ligament (ACL) injury and hip and ankle disorders in female athletes and has a more significant prevalence compared with male athletes because of numerous factors. The aim of this study is to determine if the connexion between DKV, landing errors, and non-contact ACL injury and re-injury in high-performance, adult, female team sport athletes can be eliminated by changing the frontal plane movement pattern and the landing errors during the rehabilitation process (RHB), a process which was focussed on dynamic knee stability with multidimensional single-leg jump landing training, on 3D knee balance improvement and multistimulus perturbation challenges and tasks,+ eccentric &amp; concentric exercise, strength &amp; conditioning, aerobic training that lasted from 26 - 44 weeks. Assessing and eliminating-reducing DKV during the RHB is mandatory in lowering the re-rupture rates in female professional athletes after ACL surgery and in preventing opposite knee trauma.

Performance analysis of the vectorized high order expansions method in the accurate landing problem of reusable boosters

This paper addresses the design of the terminal phase maneuver of the booster landing in the presence of initial deviations and uncertainties. The primary purpose of this study is to evaluate the effectiveness of the vectorized high order expansions method to extract commands and near-optimal trajectory, while the accurate satisfaction of the terminal conditions is of great importance. After reviewing high order expansions methods, the Vectorized High Order Expansions method is briefly discussed. Then, the solution for the booster landing problem is extracted up to the third order. To study the solution quality in the presence of uncertainties, mass, density, and gravity are assumed to be constant in extracting the 3rd order solution. The assumptions however are eliminated in the simulations, and the effectiveness of high order expansions solution is studied subjectively and numerically in the presence of initial deviations and uncertainties. After implementing simulations and considering different assumptions, it will be shown that the 3rd order solution holds a desirable quality in accurately satisfying final conditions in presence of uncertainties and initial deviations and provides far better results than the 1st order solution. Moreover, in this paper, a novel method is proposed for online updating, and the performance and effect of this modification are studied using simulations. Reviewing the results of the 3rd order solution combined with the online update strategy, it becomes clear that the implementation of the online update significantly reduces landing point errors and improves the performance of the high order method. Furthermore, the study compares the performance of this strategy with the well-known state-dependent Riccati equation method to better evaluate the effectiveness of the proposed approach.

Guidance for precision landing on asteroid using active hopping trajectory

In the landing mission on low-gravity asteroids, the probe may have a large position error when touching the surface or hop away from the desired target after a collision. To achieve a precision landing, a guidance method using an active hopping trajectory is proposed. In contrast to passive hopping, the active hopping strategy can reduce the landing errors by controlling the collision attitude sequence of the probe. The collision attitude sequence is determined by dynamically planning the hopping trajectory which consists of an active hopping phase and a braking phase. The active hopping phase achieves an expected range with a small number of hops, and the braking phase eliminates the probe's horizontal velocity and provides feedback for the range adjustment of the active hopping phase. The guidance method based on the hopping trajectory planning is then verified in a simulated asteroid landing scenario. The results show that the method is effective in reducing the landing errors, robust to the environmental parameter perturbations, and applicable to landings on inclined surfaces.

The development of a clinical screening tool to evaluate unilateral landing performance in a healthy population

ObjectivesTo develop a clinical tool to evaluate unilateral landing quality in a healthy population. The reliability of the novel tool was evaluated, and the influence of gender and leg-dominance was investigated. DesignAn experimental study for developing a test protocol, scoring criteria, and scoring method, based on observable landing errors, for the novel Unilateral Landing Error Scoring System (ULESS). SettingControlled lab environment. ParticipantsHealthy participants (25♂ and 25♀) performed the ULESS. Main outcome measuresThe ULESS was scored with video analysis. Unilateral landing performance, measured with the ULESS, was compared to bilateral landing performance. ResultsSixteen items to assess trunk, pelvic, and lower limb movement patterns during a unilateral landing task resulted in a composite score on an interval scale. Moderate to excellent intra- and inter-tester reliability (ICC(2,1) = 0.77–0.90) was determined. The ULESS was able to identify moderate to poor unilateral landing quality in subjects with good to excellent bilateral landing quality. No main effect of gender (p = 0.19) or leg-dominance (p = 0.65) on ULESS scores was found. ConclusionModerate to excellent reliability can be expected when using the newly developed protocol and scoring method. The ULESS is feasible to perform with limited materials.

Association Between Cognitive Function and Mechanical Pattern of Landing

Introduction: In examining the factors affecting sports injuries, the emphasis is always on physical variables, while cognitive and psychological characteristics can also be effective. Hence, the present study aimed to investigate the relationship between sustained attention as a neurocognitive function and landing error as a mechanical factor associated with lower limb injuries. Materials and Methods: 44 female basketball players aged 18-25 years at the national league level participated in this study. The participants were assessed using the continuous performance test, and their landing-jumping was evaluated by the landing error scoring system in two conditions of high and low cognitive load. Results: The results showed that people’s landing errors increased significantly as a result of increased cognitive needs (P=0.0001). Also, the findings revealed a positive correlation between omission and commission errors with landing error scores in both low and high cognitive load conditions (P&lt;0.05). Conclusion: Sustained attention could predict the landing error score that is considered a key risk factor of lower limb injuries. It is recommended that multiple cognitive and physical assessments be used to identify athletes at risk of injury. Hence, cognitive enhancement protocols may be effective along with physical preparation programs.

2020 도쿄올림픽대회 남자 도마 종목 연기내용 분석 : 신재환선수 금메달 획득원인과 보완방안

The purpose of this study was to analyze the exercise contents at men’s vault final at the 2020 Tokyo Olympics Games in 2021. All vault exercises(n=16) performed by 8 gymnasts were examined using video analysis by international judges. Gymnasts’s scores(difficulty, execution and final scores)and landing errors were defined as variables.<BR> Two gymnasts performed 6.0 difficulties of Yonekura(KOR) and Re Se Gwang 2(TUR). The success and errors rate for landing has affected final score and ranking. We also found that no one(16 vault exercises) has succeeded in landing phase. The overall average deduction are 1.156 points, 0.406 points for landing, 0.250 points for the 2nd flight, and 0.175 points for preflight. For Shin Jae-hwan to maintain his world ranking in men’s vault exercise, the penalty in the Yonekura element for legs separation of 0.3 during the first flight and the handstand position must be reduced. Also, we suggest that he must focus on preparation for landing and stick landing with complete twist. In addition, in the Yeo2 element, it is necessary to focus on improving hip straight during flight phase and increasing landing success rate.

Does SportsMetrics Soccer Training Improve LESS and Dynamic Balance in Soccer Players? A randomized controlled trial

Purpose: Compared with other sports, soccer is an activity with a relatively high incidence of injury. To decrease the number of injuries, prevent early retirement, and provide a healthy and safe environment for players, preventive programs are highly recommended. This study aimed to investigate the effect of Sportsmetrics Soccer Training (SMST) on Landing Error Scoring Systems (LESS) and dynamic balance in soccer players. Methods: This study was a randomized controlled trial with pretest-posttest design and training (TG) and control (CG) groups. The statistical population comprised young soccer players over 18 years old recruited from Zulfaqarnasab Soccer Academy in Sanandaj City, Iran. The study participants were 29 soccer players with three years of experience in soccer clubs. The subjects were randomly assigned into TG (n=14, mean±SD age=18.40±0.5 years, mean±SD height=180.40±6.86 cm, mean±SD weight=70.47±9.62 kg) and CG (n=15, mean±SD age=18.64±0.08 years, mean±SD height=179.57±6.72 cm, mean±SD weight=64.64±6.61 kg). The TG group performed SMST three times a week for six weeks (each session lasted 35 to 45 minutes). The CG did not receive any intervention. The LESS (intraclass correlation [ICC]=0.82-0.99) and the Y-balance (ICC=0.91- 0.99) were used for assessing landing errors and dynamic balance. The obtained data were analyzed using the Analysis of Covariance (ANCOVA) (P≤0.05) in SPSS (version 24). Results: The TG showed a significant improvement in scores of LESS (F=48.23, P=0.0001), anterior reach (F=18.26, P=0.0001), posteromedial reach (F=21.15, P=0.0001), and posterolateral reach (F=17.94, P=0.0001) in posttest compared to their baseline results. Conclusion: The present study results showed that SMST could improve LESS score and Y-balance, so we recommend that soccer coaches use SMST to prevent injury.

Effects of Open Skill Visuomotor Choice Reaction Time Training on Unanticipated Jump-Landing Stability and Quality: A Randomized Controlled Trial.

Adapting movements rapidly to unanticipated external stimuli is paramount for athletic performance and to prevent injuries. We investigated the effects of a 4-week open-skill choice-reaction training intervention on unanticipated jump-landings. Physically active adults (n = 37; mean age 27, standard deviation 2.7 years, 16 females, 21 males) were randomly allocated to one of two interventions or a control group (CG). Participants in the two intervention groups performed a 4-week visuomotor open skill choice reaction training, one for the upper and one for the lower extremities. Before and after the intervention, two different types of countermovement jumps with landings in split stance position were performed. In the (1) pre-planned condition, we informed the participants regarding the landing position (left or right foot in front position) before the jump. In the (2) unanticipated condition, this information was displayed after take-off (350–600 ms reaction time before landing). Outcomes were landing stability [peak vertical ground reaction force (pGRF) and time to stabilization (TTS)], and landing-related decision-making quality (measured by the number of landing errors). To measure extremity-specific effects, we documented the number of correct hits during the trained drills. A two-factorial (four repeated measures: two conditions, two time factors; three groups) ANCOVA was carried out; conditions = unanticipated versus pre-planned condition, time factors = pre versus post measurement, grouping variable = intervention allocation, co-variates = jumping time and self-report arousal. The training improved performance over the intervention period (upper extremity group: mean of correct choice reaction hits during 5 s drill: +3.0 hits, 95% confidence interval: 2.2–3.9 hits; lower extremity group: +1.6 hits, 0.6–2.6 hits). For pGRF (F = 8.4, p < 0.001) and landing errors (F = 17.1, p < 0.001) repeated measures effect occurred. Significantly more landing errors occurred within the unanticipated condition for all groups and measurement days. The effect in pGRF is mostly impacted by between-condition differences in the CG. No between-group or interaction effect was seen for these outcomes: pGRF (F = 0.4, p = 0.9; F = 2.3, p = 0.1) landing errors (F = 0.5, p = 0.6; F = 2.3, p = 0.1). TTS displayed a repeated measures (F = 4.9, p < 0.001, worse values under the unanticipated condition, improvement over time) and an interaction effect (F = 2.4, p = 0.03). Healthy adults can improve their choice reaction task performance by training. As almost no transfer to unanticipated landing successfulness or movement quality occurred, the effect seems to be task-specific. Lower-extremity reactions to unanticipated stimuli may be improved by more specific training regimens.

Adaptive nonlinear relative motion control of quadrotors in autonomous shipboard landings

The relative motion control for the unmanned quadrotors autonomous shipboard landings is investigated in this study. The shipboard landing missions are divided into two phases including the position approaching phase and the vertical landing phase. Relative pose kinematics and dynamics are modeled in the quadrotor’s body-fixed frame, where the kinematic couplings resulted from the difference between ship’s centre of mass and desired landing site and the unknown external disturbances of two vehicles are considered in the modeling and control design. In the position approaching phase, because of the under-actuated property of quadrotors, the adaptive backstepping technique is combined with an auxiliary system and a command filter to develop the guidance and control laws. Subsequently, the relative altitude-attitude controller is designed for the vertical landing phase. Stability analysis shows that the position approaching errors in the first phase and the landing errors in the second phase ultimately converge to small neighborhoods of zero, and numerical simulation validates the effectiveness of the proposed strategy.

Output-constrained fixed-time control for autonomous ship landing of helicopters

In this paper, we consider a fixed-time autonomous ship landing control design for helicopters subject to asymmetric output constraints, model uncertainties and external perturbations. By incorporating a universal barrier function into the backstepping design, an output-constrained fixed-time control algorithm is proposed, where a new adaptive estimation method is introduced to compensate the effects resulting from uncertainties and disturbances. To avoid crash and overcome the limitation of the helicopter’s under-actuated property, the whole landing operation is completed in a dual-phase landing sequence with two controllers, which are both designed based on the output-constrained fixed-time control algorithm. The proposed control strategy guarantees that the tracking and landing errors converge into a small neighborhood of zero in a fixed settling time without violating the constraint requirement. Numerical comparative simulations are executed to further verify the prominent control performance.

Precision Landing Test and Simulation of the Agricultural UAV on Apron.

Unmanned aerial vehicle (UAV) has been used to assist agricultural production. Precision landing control of UAV is critical for application of it in some specific areas such as greenhouses or livestock/poultry houses. For controlling UAV landing on a fixed or mobile apron/platform accurately, this study proposed an automatic method and tested it under three scenarios: (1) UAV landing at high operating altitude based on the GPS signal of the mobile apron; (2) UAV landing at low operating altitude based on the image recognition on the mobile apron; and (3) UAV landing progress control based on the fixed landing device and image detection to achieve a stable landing action. To verify the effectiveness of the proposed control method, apron at both stationary and mobile (e.g., 3 km/h moving speed) statuses were tested. Besides, a simulation was conducted for the UAV landing on a fixed apron by using a commercial poultry house as a model (135 L × 15 W × 3 H m). Results show that the average landing errors in high altitude and low altitude can be controlled within 6.78 cm and 13.29 cm, respectively. For the poultry house simulation, the landing errors were 6.22 ± 2.59 cm, 6.79 ± 3.26 cm, and 7.14 ± 2.41cm at the running speed of 2 km/h, 3 km/h, and 4 km/h, respectively. This study provides the basis for applying the UAV in agricultural facilities such as poultry or animal houses where requires a stricter landing control than open fields.

ACL Injury Prediction in Footballers Using Landing Error Scoring System (LESS)

Background: The use of clinical field assessment tools is popular in sports rehabilitation settings. The purpose of these tools is not only prediction of injury but also to assist in development of injury prevention programs. Landing Error Scoring System (LESS) is a clinical tool that evaluates biomechanical performance during a jump-landing task with particular focus on aspects related to an increased risk for ACL injury. Objective: Of this study was to find the most common faulty biomechanics in football players. Method: This is an evaluation-based study which predicts the risk of ACL injuries in 30 football players based on their jump landing mechanics. This evaluation was carried out with the help of software Kinovea that helps in analysis of joint kinematics. The data captured with the help of off-the-shelf cameras in frontal and sagittal planes and analysed. The frequency of common errors was identified. Result: It was found out that 20% of the players had poor landing mechanics having maximum errors, 20% had moderate errors, while 13% had good score and 47% had excellent landing mechanics. The most common error was knee valgus at initial contact, stance width wider and knee valgus displacement. Conclusion: LESS is beneficial in identification of faulty biomechanics. LESS when used along with Kinovea helps analyse common jump landing errors. Knee valgus along with internal rotation of tibia was found to be the common error which predisposes footballers to ACL injury.

Are biomechanical stability deficits during unplanned single-leg landings related to specific markers of cognitive function?

ObjectivesCognitive skills such as working memory or inhibitory control are suggested to have an impact on injury risk during time-constrained athletic movements. Thus, the aim of this study was to gain further insights into the cognitive processes associated with biomechanical stability in unplanned jump-landings. DesignCross-sectional. MethodsTwenty male participants (27±4years) performed 70 counter-movement jumps with single-leg landings on a pressure plate. Equally balanced and in randomized order, these were to be performed either planned (landing leg indicated before take-off) or unplanned (visual cue during flight). Biomechanical stability was estimated from vertical peak ground reaction force (pGRF), time to stabilization (TTS), center of pressure path length (COP), and the number of standing errors (ground touch with free leg). In addition, decision-making was assessed as the amount of landing errors (wrong/both feet) in the unplanned condition. Cognitiive function was measured using computerized as well as pen-and-paper-testing. ResultsUnplanned landings produced higher COP values (p<0.001, d=1.1) and more standing errors (p<0.001, d=0.9) than the pre-planned condition. Decreased postural stability (COP) was related to lower inhibitory control (p=0.036, r=0.48). There was a correlation between the increase in standing errors and better cognitive flexibility/working memory (p=0.037, r=−0.48) and short-term memory (p=0.028, r=0.50). The opposite was found for the unplanned landing errors: poor decision-making was associated with deficits in cognitive flexibility/working memory (p=0.022, r=0.54) and short-term memory (p=0.019, r=−0.55). ConclusionsCognitive function may be an important, but under-researched moderator of unplanned jump-landing safety. Further research should elucidate the development of training methods aiming to improve movement-related decision-making and landing stability under time constraints.