• Title/Summary/Keyword: Landing velocity

Search Result 98, Processing Time 0.021 seconds

Analysis of Optimal Landing Trajectory in Attitude Angular Velocity Influence at Powered Descent Phase of Robotic Lunar Lander (무인 달착륙선의 동력하강단계에서 자세각속도 영향에 따른 최적화 착륙궤적 분석)

  • Park, Jae-ik;Rew, Dong-Young
    • Journal of the Korean Society for Aeronautical & Space Sciences
    • /
    • v.46 no.5
    • /
    • pp.402-409
    • /
    • 2018
  • In this paper, we propose a lunar landing scenario of a robotic lunar landing mission and implements an optimal landing trajectory at the powered descent phase based on the proposed scenario. The change of attitude of the lunar lander in the power descent phase affects not only the amount of fuel used but also sensor operation of image based navigation. Therefore, the attitude angular velocity is included in the cost function of the optimal control problem to minimize the unnecessary attitude change when the optimal landing trajectory generates at powered descent phase of the lunar landing. The influence of the change of attitude angular velocity on the optimal landing trajectory are analyzed by adjusting the weight of the attitude angular velocity. Based on the results, we suggest the proper weight to generate the optimal landing trajectory in order to minimize the influence of the attitude angular velocity.

Effects of Landing Height and Knee Joint Muscle Fatigue on Movement of the Lower Extremity during Cutting After Landing (착지 높이와 무릎관절 근육 피로가 착지 후 방향 전환 동작 시 하지관절의 움직임에 미치는 영향)

  • Kim, You-Kyung;Youm, Chang-Hong
    • Korean Journal of Applied Biomechanics
    • /
    • v.25 no.3
    • /
    • pp.311-322
    • /
    • 2015
  • Objective : The purpose of this study was to investigate the effects of landing height and knee joint muscle fatigue on the movement of the lower extremity during cutting after landing. Method : Subjects included 29 adults (age: $20.83{\pm}1.56years$, height: $172.42{\pm}9.51cm$, weight: $65.07{\pm}10.18kg$). The subjects were asked to stand on their dominant lower limb on jump stands that were 30 and 40 cm in height and jump from each stand to land with the dominant lower limb on a force plate making a side step cutting move at a $45^{\circ}$ angle with the non-dominant lower limb. The fatigue level at 30% of the knee extension peak torque using an isokinetic dynamometer. Results : The results showed that the difference of landing height increased maximum range of motion and angular velocity of hip, knee, and ankle joints in the sagittal plane, and in the angular velocity of motion of the hip joint in the sagittal plane. The maximum range of motion of the knee joint in the sagittal plane and the frontal plane decreased on landing from both heights after the fatigue exercise. The angular velocity of the hip joint in the sagittal plane, and the maximum range of motion of the hip joint in the transverse plane decreased for both landing heights after the fatigue exercise. The angular velocity of the hip joint in the frontal plane decreased for the 30 cm landing height after the fatigue exercise. On the other hand, the angular velocity and maximum range of motion of the ankle joint in the sagittal plane for both landing heights, and the angular velocity and maximum range of motion of the ankle joint in the frontal plane increased on landing from the 40 cm height after the fatigue exercise. Conclusion : Different landing heights of 30 and 40 cm and 30% fatigue of peak torque of knee extensor found a forefoot and stiff landing strategy, when cutting after landing. These results might be due to decline in the shock absorption capability of the knee joint and the movement capability related to cutting while increasing the contribution of the ankle joint, which may cause increased ankle joint injuries.

Dynamic Analysis of Aircraft Landing Gear under Nonstationary Random Excitations (비정상 랜덤 가진력을 받는 항공기 착륙장치의 동특성 해석)

  • 황재혁;유병성;박명호
    • Journal of KSNVE
    • /
    • v.8 no.2
    • /
    • pp.251-259
    • /
    • 1998
  • The motion of an aircraft landing gear over rough runway at variable speed is nonstationary. In this paper, a method for the computation of nonstationary response variance is presented which uses a state space form for the combination of landing gear and runway excitation. The dynamic characteristics of the landing gear under nonstationary random excitations has also been analyzed using the proposed method. The formulation is for linear systems of arbitrary order and allows any deterministic velocity history. It has been found by a series of simulation that correlation parameter, damping coefficients of landing gear and tire, and velocity profiles play a prominent role on the dynamic characteristics.

  • PDF

The Kinematical Analysis of Parallel Bars Double Piked Landing Motion (평행봉 double piked 내리기 동작의 운동학적 분석)

  • Kwon, Oh-Seok
    • Korean Journal of Applied Biomechanics
    • /
    • v.20 no.3
    • /
    • pp.311-318
    • /
    • 2010
  • This study examined the double piked dismount among the landing techniques of parallel bars based on three-dimensional motion analysis. Four male national gymnasts were the subjects. This study was performed to provide quantitative data highlighting players strengths and weaknesses to enable more stable landing technique. The variables analyzed were the position and velocity of center of gravity(CG) and angles of shoulder joints, hip joints, and trunk. The results are as follows: S1 secured the height of flight with fast vertical rise. After the easy spin in the air, he conducted a stable landing maintaining a proper hip joints angle. S2, S3, and S4, however, began the backward somersault already before leaving the bars, so they moved backward greatly making it more difficult to achieve a higher flight path. As a result, they couldn't control the velocity of their backward movement at landing. For a stable landing, they have to maintain the negative shoulder angle when rising, minimize both antero-posterioror side-to-side movements by doing a strong tap using hip joints, to secure the height of flight before the somersault. Results also show that at the descent, they should conduct rapid spinning by increasing their shoulder and hip joints to the maximum while controlling their velocity.

Analysis of Successful Landing by the Type of the Salto Backward (뒤 공중 돌기 유형에 따른 착지동작의 성공요인 분석)

  • Han, Yoon-soo
    • Korean Journal of Applied Biomechanics
    • /
    • v.14 no.1
    • /
    • pp.1-12
    • /
    • 2004
  • The purpose of this study is to provide training materials for practical use by investigating the kinematical variables of the successful landing by the type of the salto backward such as Tuck, Pike. For this study, the subjects are 4 male national gymnasts using 3-dimensional cinematographic method. Based on the results of this study, the conclusions are drawn as follows. 1. In flight phase, Tuck and Pike show fast extension after completing minimum angle of hip joint passing through the peak. It is very important factor to control body with gaining time before landing while decreasing the velocity of flight rotaion. 2. In Landing phase, the angles of each joint for successful landing are shown as $92deg{\sim}100deg$ for knee angle, $52deg{\sim}57deg$ for hip angle, and $56deg{\sim}70deg$ for shoulder angle. 3. Tuck and Pike dramatically decrease the height of COG, and horizontal/vertical velocity of COG from TD to LD. Also, it is shown that the knee angle, the hip angle and the shoulder angle decrease drastically. On the other hand, the angular velocity of trunk rotation shows negative direction and due to this, the angle of trunk rotation is shown as re-flexion.

Dynamic Analysis of Aircraft Landing Gear under Nonstationary Random Excitations (비정상 랜덤 가진력을 받는 항공기 착륙장치의 동특성 해석)

  • 황재혁;유병성;박명호
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 1997.04a
    • /
    • pp.60-68
    • /
    • 1997
  • The motion of an aircraft landing gear over rough runway at variable speed is nonstationary. In this paper a method for the computation of nonstationary response variance is presented which uses a state space form for the combination of landing gear and runway excitation. The dynamic characteristics of the landing gear under nonstationary random excitations has also been analyzed using the proposed method. The formulation is for linear systems of arbitrary order and allows any deterministic velocity history. It has been found by a series of simulation that correlation parameter, damping coefficients of landing gear and tire, and velocity profiles plays a prominent role on the dynamic characteristics.

  • PDF

Effect of Added Mass between Male and Female on The Lower Extremity Joints Angular Velocity, Moment, Absorb Energy During Drop Landing (착지 시 외부 무게 부하에 따른 남성과 여성의 하지 관절 각속도, 모멘트, 에너지 흡수에 미치는 영향)

  • Kwon, Moon-Seok
    • Korean Journal of Applied Biomechanics
    • /
    • v.22 no.3
    • /
    • pp.325-332
    • /
    • 2012
  • This study aimed to analyze the effects of external load between male and female on angular velocity, moment, and absorbed energy of the lower-extremity joints during drop landing. The study subjects were 9 male($mass=70.82{\pm}4.64kg$, $height=1.71{\pm}0.04m$, $age=24.5{\pm}1.84years$), 9 female($mass=50.14{\pm}4.09kg$, $height=1.61{\pm}0.03m$, $age=23.6{\pm}2.62years$), without any serious musculoskeletal, coordination, balance, or joint/ligament problems for 1 year before the study. The angular velocity, flexion/extension and abduction/adduction moments, and absorbed energy of the lower-extremity joints were compared between the men and women during drop landing under 4 different conditions of external load(0%, 8%, 16%, and 24%) by using two-way repeated ANOVA(p < .05). The women landed with a greater peak angular velocity of the ankle joint, greater peak inversion moment, and lower peak hip-extension moment than the men did, under all 4 conditions. Additionally, the landing characteristics of the women were distinct from those of the men; the women showed a greater peak knee-adduction moment and greater absorbed energy of the knee joint. These differences indicate that anterior cruciate ligament(ACL) strain was greater in the women than in the men and therefore, women may be at a higher potential risk for noncontact injuries of the ACL with an increase in external load.

Analysis of the Differences of the Shock Attenuation Strategy between Double-leg and Single-leg Landing on Sagittal Plane using Statistical Parametric Mapping (Statistical Parametric Mapping을 이용한 시상면에서의 양발 착지와 외발 착지의 전략 차이)

  • Ha, Sunghe;Park, Sang-Kyoon;Lee, Sae Yong
    • Korean Journal of Applied Biomechanics
    • /
    • v.29 no.4
    • /
    • pp.255-261
    • /
    • 2019
  • Objective: The purpose of this study was to investigate differences of shock attenuation strategies between double-leg and single-leg landing on sagittal plane using statistical parametric mapping. Method: Nine healthy female professional soccer players (age: 24.0±2.5 yrs, height: 164.9±3.3 cm, weight: 55.7±6.6 kg, career: 11.2±1.4 yrs) were participated in this study. The subjects performed 10 times of double-leg and single-leg landing from the box of 30 cm height onto force plates respectively. The ground reaction force, angle, moment, angular velocity, and power of the ankle, knee, and hip joint on sagittal plane was calculated from initial contact to maximum knee flexion during landing phase. Statistical parametric mapping was used to compare the biomechanical variables of double-leg and single-leg landing of the dominant leg throughout the landing phase. Each mean difference of variables was analyzed using a paired t-test and alpha level was set to 0.05. Results: For the biomechanical variables, significantly increased vertical ground reaction force, plantarflexion moment of the ankle joint, negative ankle joint power and extension moment of the hip joint were found in single-leg landing compared to double-leg landing (p<.05). In addition, the flexion angle and angular velocity of the knee and hip joint in double-leg landing were observed significantly greater than single-leg landing, respectively (p<.05). Conclusion: These findings suggested that negative joint power and plantarflexion moment of the ankle joint can contribute to shock absorption during single-leg landing and may be the factors for preventing the musculoskeletal injuries of the lower extremity by an external force.

Velocity Pattern Generation for the Position Control Elevator (엘리베이터 위치제어를 위한 속도패턴 발생)

  • 김경서;박창훈;강기호;한권상
    • The Transactions of the Korean Institute of Power Electronics
    • /
    • v.4 no.6
    • /
    • pp.616-623
    • /
    • 1999
  • Elevator velocity pattern is basL'C! on combining the time-based velocity pattern according to which the car m trip from starting position to vicinity of target position, and distance-based velocity pattern for precise landing ( of car. To obtain the lide comfortability, the impact caused by velocity pattern switching should be minimizLD b by removing the discontinuity of velocity and acceleration. In this paper, new velocity pattern generation m method which ensure the continuity of velocity and acceleration during pattern switching is proposed. P ProPOSLD velocity pattern also shorten the landing time to the target position.

  • PDF

The kinematic analysis of the Hurdling of Men's 110m Hurdle (남자 국가대표 110m허들선수의 허들동작에 관한 운동학적 분석)

  • Lee, Jung-Ho
    • Korean Journal of Applied Biomechanics
    • /
    • v.14 no.1
    • /
    • pp.83-98
    • /
    • 2004
  • The purpose of this study was to determine the kinematic variables of the hurdling for a korea record holder (A) and a national hurdle representative (B). after the kinematic variables such the distance and the distance and height of C.G, the velocity and the angle were analyzed about the hurdling. The results were summarized as follows; 1. In terms of the distance and the height of C.G, subject A showed long in horizontal distance from C.G to the take-off phase, but showed short in the landing phase. Subject B showed short in horizontal distance from C.G to the take-off phase, and showed long in the landing phase. 2. In terms of the velocity of C.G, Subject A showed fast C.G velocity in horizontal direction to the braking phase, Subject A and B showed slower C.G velority in the landing phase, but Subject A showed height C.G velocity in vertical direction to the to the take-off, the landing, and propulsion phase 3. In terms of the angle of C.G and lean of C.G to front at the braking and the take-off phase. Subject A kept the less angle in the maximum trunk lean to front at the flight phase as comparison with Subject B. 4. In terms of the velocity of the knee and the ankle joint. Subject A showed fast in the resultant velocity of the left ankle joint the take-off phase, but showed slow in the left knee joint. Subject B showed fast in the resultant velocity of the left knee joint the take-off phase, but showed slow in the right knee and the right ankle joint.