# Progress in Ski Jumping Technology Based on Biomechanical Sport Research Methods
## 2 Progress of Different Research Methods
### Motion Video Capture and Analysis
used a differential global navigation satellite system (GNSS) to measure the difference between elite ski jumpers on a normal (HS106) and large hill (HS140). They concluded that the high lift-drag ratio had no significant effect on the flight distance of HS106 but significantly impacted the flight distance of HS140 [40]. It is a pity that the visual field of these images does not cover the stable flight stage and that there is also a lack of synchronous data on the different motion stages to describe overall motion performance. A new technology developed during the Beijing Winter Olympics--the Intel 3 DAT athlete tracking system that assists scientific training, using video motion capture technology and an AI image processing system--can realize the three-dimensional attitude reconstruction of athletes, perform accurate quantitative evaluation of movements, and control measurement error below 5 mm [41]. Figure 1 inllstrated an \"ultra-high-speed 4K orbital camera system\" which was used in the Beijing Winter Olympics. It was developed by the China Central Television, called the Cheetah system, which uses \"time slice\" technology to freeze multiple key gestures of the complete motion process in the same picture and completes the key indicator analysis within 3 s [42]. [PERSON] and his colleagues used the kinematic data inversion method to calculate the ground reaction force from the kinematic data collected during mountain platform jumps and compared it with the take-off force measured by the Pedar insole simultaneously. The results showed a reasonably high agreement between measured and calculated forces (less than 5% difference when considering aerodynamic lift), justifying the estimation of ground reaction forces from kinematic data [34]. [PERSON] et al. used the inverse dynamics method to calculate the kinematics data collected during the competition: the external force on the centroid; the moment of the ankle joint, knee joint, and hip joint; and the torque on the snowboard during the take-off and early flight stages [43]. Multi-disciplinary principles underpin ski jumping performance; different mountain conditions, climate conditions, departure grids, and measurement tools will impact the research results. However, a consensus can be reached in kinematic research that the final velocity of each different motion stage becomes the initial velocity of the next stage and significantly impacts the final flight distance. The main problem faced by motion video capture and analysis is measurement accuracy, such as errors in measuring the body attitude angle when wearing a ski suit, the measurement error of the snowboard angle, and the resulting attitude when the mountain background or protection fence interferes. Errors in angle measurement, centroid estimation, and the position of the centroid and the resultant moment in the flight system are essential reasons for determining flight. On the other hand, there needs to be more data consistency between different hardware systems and video analysis (parsing) software. At the same time, ski jumpers are limited by nerve fatigue, and the number of videos that can be collected in daily ski jumping training and sports technology are also limited. Most of the conclusions reached in the literature are qualitative descriptions and time series diagrams of various parameters in the motion process based on experimental data [37], and there are few clear conclusions regarding quantitative analysis.