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第三十九届中国控制会议

作者： Li Pengcheng Yao Xiaolan Xu Ning School of Automation Beijing Institute of Technology

In this paper, the trajectory optimization of alpine skiing is studied based on Radau pseudospectral method（RPM）. First, the kinetic model of alpine skiing is established by Newton’s second law, then the boundary constraints are considered, and the trajectory optimization of alpine skiing is converted into the optimal control problem which takes the minimum time consumption as the cost function. Finally, the optimal control problem is transcribed to a nonlinear programming problem（NLP） by RPM, and the optimal solution is obtained. Simulation results show that RPM can effectively generate a continuous optimal path meet the requirement of accuracy.

关键词： alpine skiing Trajectory optimization Optimal control Radau pseudospectral method

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“When you’re down, stay down”:A lesson for all competitive alpine skiers supported by an ACL rupture measured in vivo

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Journal of Sport and Health Science 2022年第1期11卷 14-20页

作者： Jörg Spöorri Erich Müller Josef Kröoll Sports Medical Research Group Department of OrthopaedicsBalgrist University HospitalUniversity of ZurichZurich 8008Switzerland University Centre for Prevention and Sports Medicine Department of OrthopaedicsBalgrist University HospitalUniversity of ZurichZurich 8008Switzerland Department of Sport Science and Kinesiology University of SalzburgHallein-Ri 5400Austria

Background:During an experiment,a ski racer equipped with various measurement devices suffered an anterior cruciate ligament(ACL)rupture in his right *** aim of this study was to describe the underlying injury mechanism from a functional ***:Eight giant slalom turns(i.e.,4 left turns),followed by 1 left turn at which the ACL injury occurred,were recorded by 2 video cameras,electromyography of 4 relevant muscle groups,inertial measurement units to measure knee and hip angles,and pressure insoles to determine ground reaction ***:Due to a loss of balance,the ski racer began to slide sideways at the apex of a left *** sliding,his right(outside)leg was actively abducted upward without touching the *** ski racer then attempted to stand up again by dropping his leg back towards the snow *** end of this dropping was accompanied by a decrease in electromyographic activity in the knee stabilizing *** the inside edge of the outer ski caught the snow surface,a rapidly increasing peak force,knee flexion,and an aggressive sudden activation of the vastus medialis muscle were observed,while biceps femoris and rectus femoris further decreased their activation *** likely resulted in excessive anterior translation of the tibia relative to the femur,causing damage to the ***:Our example emphasizes that ski racers should not get up until they stop ***:“When you’re down,stay down.”

关键词： alpine skiing Athletes Injury mechanism Injury prevention Knee injuries

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The Influence of Ski Type on Muscle Activity, Performance, and Self-Efficacy in Young alpine Ski Racers

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Journal of Science in Sport and Exercise 2021年第3期3卷 312-319页

作者： Heidi B.Nunnikhoven Cory Snyder Ronald W.Kipp Michael J.Decker John G.Seifert Movement Science Laboratory Montana State UniversityBozemanMT 59717USA Squaw Valley Ski Team Olympic ValleyCAUSA University of Denver DenverCOUSA Department of Sport and Exercise Science University of SalzburgHallein-RifAustria Athletes Performance Center Red Bull SportsSalzburgAustria

Wide skis are the most popular ski sold in the United States and are skied routinely in all types of terrain,especially by young *** study investigated the influence of slalom(SL,64 mm underfoot width)and wide skis(WS,97.7 mm underfoot width)on perceptual responses,timed performance,edge inclination angles,and EMG in young alpine ski *** subjects,mean age 12.8±0.5 years,completed one run on each of two courses which were set to approximate the different turning radii of each *** completed a Likert-type questionnaire to assess components of self-efficacy after each *** activity was recorded on the gluteus medius(GM),vastus lateralis,tibialis anterior and peroneus longus(PL).Per-ceptions of confidence,aggressiveness,speed,and skiing on line were significantly greater,by about 31%,for SL than WS regardless of *** times were significantly less by 4% for SL than WS,peak edge inclination angle was 7%greater for SL than WS,and PL activity was 40% less for SL compared to *** racers are developing skills to improve their racing techniques and are still forming technique strategies to deal with the many factors present in skiing which may disrupt learning *** lower perceptual and performance responses on WS,young ski racers who ski on groomed snow with WS could be interfering with the adaptation of fundamental racing technique at a critical time in their development.

关键词： alpine skiing Electromyography Ski type Confidence

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Research on indoor multi-degree-of-freedom ski training system

Research on indoor multi-degree-of-freedom ski training syst...

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第40届中国控制会议

作者： Boyang Li Qing Fei Hongqing Cao School of Automation Beijing Institute of Technology

In this paper, a multi-freedom ski training system is introduced for indoor alpine skiing training and *** translation platform and the six-degree-of-freedom platform are adopted in the system to realize a wide range of slalom training and terrain simulation. Combining the washout algorithm with the virtual scene and terrain information in Unity3 D, the system provides users with the real physical and visual experience of alpine skiing. In the design of washout algorithm, sparrow search algorithm（SSA） is used to optimize the parameters of washout filter, which can achieve a less sensation error and a higher efficiency of the workspace usage. Simulation and experimental results show that our system can give users a real alpine skiing experience, and facilitate the users to ski training and experience the terrain of the ski trail.

关键词： alpine skiing 6-DOF Platform Washout Algorithm Sparrow Search Algorithm Unity3D

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