A posture and trajectory visualization method for precise cornering in competitive bobsleigh

Abstract

The present invention discloses a method for visualizing the posture and trajectory of precise cornering in competitive bobsleigh events. The method comprises the following steps: determining whether a trigger signal has been received; if so, the bobsleigh appears and the laser array begins sampling until the bobsleigh leaves; calculating the trajectory coordinates, processing the binary (t, D) to obtain the bobsleigh trajectory coordinate binary (t, Pos); calculating the bobsleigh speed data; performing real-time visualization, performing a linear transformation on the Pos matrix, and after completing the first coordinate system, rendering the bobsleigh's posture, trajectory, and speed information to the key corners of the track model; establishing a cornering evaluation model, calculating the evaluation parameters that affect the cornering time score, and using the Pearson correlation coefficient to quantify the correlation between the score and each evaluation parameter to reduce the cornering time. The present invention can achieve centimeter-level positioning accuracy, fully parallelizes the laser ranging array data processing, has high real-time performance, and fundamentally avoids the defects of inconsistent posture, trajectory, and speed information.

Description

Technical Field

[0001] The present invention relates to a visualization technology for competitive bobsleigh motion data, specifically a method for visualizing posture and trajectory for precise cornering in competitive bobsleigh events. Background Art

[0002] Competitive bobsleigh is an extremely fast-moving sport, reaching speeds exceeding 140 km / h, making it difficult for athletes to accurately perceive their gliding state and characteristics. Competitions take place on an icy track approximately 1500-2000 meters long, with a large vertical drop and numerous curves. The bottleneck for athletes' competitive performance lies in safely negotiating the curves at high speeds. Capturing the trajectory and posture of a bobsleigh through corners is crucial for training athletes. However, the characteristics of bobsleigh and luge make achieving this requirement extremely challenging.

[0003] The most common method for assessing athlete performance is to install photocells on the track to record the athlete's time and speed as they pass. Chinese patent CN114663498A discloses a "distributed point big data service and method," describing a speed identifier placed on a helmet to collect current speed. If the athlete is currently at top speed, the device determines whether the athlete's posture is seriously out of alignment based on the degree of symmetry of the ice surface ahead. If this is determined to be a serious deviation, both track and vehicle deceleration measures are implemented.

[0004] Photoelectric gates can only capture instantaneous information at specific locations, but cannot reveal the continuous state and characteristics of the entire skating process, especially around corners, which are crucial for competitive performance. The technical solution proposed in Chinese patent CN114663498A can only quantify speed, but cannot obtain high-precision trajectory or quantitative posture information, making it of limited help in improving athletes' skating skills and competitive performance.

[0005] Existing positioning systems calculate the trajectory of high-speed objects in a non-real-time and delayed manner. Satellite-based positioning systems cannot locate objects indoors if the signal is lost, and signal loss also occurs outdoors. Obtaining a high-precision trajectory requires additional post-processing after the object has completed its movement, which results in a delay in the solution. Furthermore, IMU-based positioning systems also suffer from lag issues.

[0006] Because the snowmobile moves so quickly, traditional single-sensor sensing methods are prone to loss of position due to the time required for hardware startup and communication. Furthermore, current positioning systems have a low positioning frequency and cannot achieve high accuracy in high-speed scenarios.

[0007] In terms of visualization and data twinning, existing positioning technologies often use longitude and latitude coordinates to determine object trajectories, which are inconsistent with the building model's coordinate system. This conversion can result in a loss of positioning accuracy. However, the trajectory coordinates calculated by the laser array positioning system can be converted to the building model coordinate system through a linear transformation, without loss of accuracy. Summary of the Invention

[0008] In response to the above-mentioned defects and improvement needs of the existing technology, the present invention provides a posture and trajectory visualization method for precise cornering in competitive bobsleigh events. While ensuring the safety of athletes' sliding, a laser ranging array can be used to collect the trajectory and posture information of the bobsleigh and skeleton at the bend, and these data can be visualized to achieve accurate perception and integration of the sliding state of the bobsleigh and skeleton, thereby solving the technical problems of the national bobsleigh and skeleton team in analyzing the sliding rules and winning factors, and can effectively help athletes improve their sliding skills and competitive results.

[0009] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0010] The present invention provides a method for visualizing posture and trajectory of precise cornering in competitive bobsleigh events, comprising the following steps:

[0011] 1) Determine whether a trigger signal is received. If a trigger signal is received, it means that a snowmobile has appeared, and the laser array begins sampling until the snowmobile leaves the laser array;

[0012] 2) Calculate the track coordinates: process the output tuple (t, D) in step 1) to obtain the track coordinate tuple (t, Pos);

[0013] 3) Calculation of bobsleigh speed data;

[0014] 4) Real-time visualization: linear transformation of the Pos matrix is ​​performed. After completing the coordinate system, the bobsleigh’s posture, trajectory, and speed information are rendered to the key corners of the track model to ensure real-time visualization.

[0015] 5) Establish a cornering evaluation model. After the above data collection process, the evaluation parameters that affect the cornering time score are calculated. The cornering evaluation model uses the Pearson correlation coefficient to quantify the correlation between the score and each evaluation parameter, so that athletes can conduct targeted training to reduce cornering time.

[0016] Step 1) is specifically as follows:

[0017] 101) A trigger signal generating device is arranged in front of the laser array;

[0018] 102) generating a trigger signal by a trigger signal generating device;

[0019] 103) After the laser array enabling component receives the trigger signal, the laser array starts sampling until the snowmobile leaves the laser array. The data output by the laser array is a binary tuple: (t, D), where t is the sampling timestamp and D is the distance matrix, which is defined as follows:

[0020]

[0021] The size of the laser array is m*n, and the bobsleigh attitude matrix Q can be obtained after filtering.

[0022] The trigger signal generating device integrates a vibration sensor, a Hall sensor and a light curtain sensor.

[0023] Step 2) trajectory coordinate calculation is to process the output of step 2) two-tuple (t, D) to obtain the snowmobile trajectory coordinate two-tuple (t, Pos), specifically:

[0024] 201) Pos is the coordinate matrix of the snow vehicle trajectory at time t, which is defined as follows:

[0025]

[0026] where x i is the x-axis coordinate calculated by the cross section of the i-th laser array, y i is the y-axis coordinate calculated by the cross section of the i-th laser array, z i is the z-axis coordinate calculated from the i-th laser array cross section, 1≤i≤m;

[0027] When the snowmobile passes through the laser array, a cross-sectional curve of the snowmobile is obtained, and the curve is converted into a polygon by simplifying the curve into a straight line.

[0028] 202) After obtaining the posture matrix Q, the centroid of the polygon formed by the posture matrix Q is calculated;

[0029] 203) x in the Pos matrix i The coordinates are determined by the installation position of the laser array and the calculation rules are as follows:

[0030]

[0031] Among them, offset is along the track axis x i The offset distance relative to x1, x1 is the x-axis coordinate of the first row of laser nodes, its value is 0, x i is the x-axis coordinate of the laser node row numbered i;

[0032] 204) According to the installation position of each laser node in the laser matrix, determine the L matrix, which is defined as follows:

[0033]

[0034] l i,j Represents the y-coordinate of the laser node numbered (i, j); for the laser node numbered (i, j), its coordinate value is (x i ,l ij ,0);1≤i≤m,1≤j≤n;

[0035] 205) For the Pos matrix (y i ,z i ), calculated using the following formula:

[0036]

[0037]

[0038]

[0039] Where A is an intermediate variable in the calculation process, representing the area of ​​the polygon approximating the cross section of the snowmobile, n is the number of laser array rows, d i,j The ranging result returned by the laser ranging node numbered (i, j);

[0040] At this point, the solution of the Pos matrix is ​​completed, and the trajectory of the snowmobile and the binary (t, D) are obtained.

[0041] Step 3) Calculate the snowmobile speed data as follows:

[0042] 301) for (1.1)(1.2) at speed 2 The tuple represents the speed of the snowmobile at time t:

[0043]

[0044] Mean represents the mean operation, Pos t is the snowmobile trajectory matrix at time t, Pos t-1 is the previous snowmobile trajectory matrix at the adjacent t time, Δt is Pos t With Pos t-1 The time interval between two sampling calculations;

[0045] 302) Using the Mean function to calculate the mean value of the matrix column, the speed v of the snowmobile is:

[0046]

[0047] in is the speed of the bobsleigh.

[0048] Step 5) The evaluation parameters that affect the cornering time score include: track length len, cornering entry angle deg_in, cornering exit angle deg_out, maximum cornering speed v_max, minimum cornering speed v_min, and average cornering speed v_avr; where the cornering entry angle deg_in and cornering exit angle deg_out are calculated based on the curvature of the track curve.

[0049] In step 4), the Pos matrix is ​​transformed into Pos′ through threading. The Pos′ coordinate system is the three-dimensional track model coordinate system. The calculation formula is as follows:

[0050] Pos'=RPos

[0051] Where R is the rotation matrix.

[0052] The present invention has the following beneficial effects and advantages:

[0053] 1. This paper proposes a method for visualizing the posture and trajectory of competitive bobsleigh for precise cornering. Using a laser array, the posture of the bobsleigh and luge can be captured at high frequency at key corners on the track, and the trajectory can be calculated. Speed ​​information is then derived from the trajectory, achieving centimeter-level positioning accuracy. The laser ranging array data processing is fully parallelized, resulting in high real-time performance.

[0054] 2. The method of the present invention can simultaneously obtain the posture, trajectory and speed of the bobsleigh and snowmobile, fundamentally avoiding the inconsistency of the three pieces of information. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 This is a flow chart of the method for visualizing posture and trajectory for precise cornering in competitive bobsleigh events according to the present invention;

[0056] Figure 2 A system architecture for application of the method of the present invention;

[0057] Figure 3 This is a diagram showing the software components of the method of the present invention;

[0058] Figure 4 A cross-sectional view of the laser array structure used in the method of the present invention;

[0059] Figure 5 This is a three-dimensional schematic diagram of the laser array structure used in the method of the present invention. DETAILED DESCRIPTION

[0060] The present invention will be further described below with reference to the accompanying drawings.

[0061] like Figure 1 As shown, the present invention proposes a posture and trajectory visualization method for precise cornering in competitive bobsleigh events, comprising the following steps:

[0062] 1) Determine whether a trigger signal is received. If a trigger signal is received, it means that a snowmobile has appeared, and the laser array begins sampling until the snowmobile leaves the laser array;

[0063] 2) Calculate the track coordinates: process the output tuple (t, D) in step 1) to obtain the track coordinate tuple (t, Pos);

[0064] 3) Calculation of bobsleigh speed data;

[0065] 4) Real-time visualization: linear transformation of the Pos matrix is ​​performed. After completing the coordinate system, the bobsleigh’s posture, trajectory, and speed information are rendered to the key corners of the track model to ensure real-time visualization.

[0066] 5) Establish a cornering evaluation model. After the above data collection process, the evaluation parameters that affect the cornering time score are calculated. The cornering evaluation model uses the Pearson correlation coefficient to quantify the correlation between the score and each evaluation parameter, so that athletes can conduct targeted training to reduce cornering time.

[0067] Step 1) is specifically as follows:

[0068] 101) A trigger signal generating device is arranged in front of the laser array;

[0069] 102) generating a trigger signal by a trigger signal generating device;

[0070] The trigger signal is generated by a trigger signal generating device, which has the characteristics of strong fault tolerance and high sensitivity; the device needs to be arranged in front of the laser array, greater than or equal to 30m; the trigger signal generating device integrates vibration sensors, Hall sensors, and light curtain sensors to avoid the failure to generate a trigger signal due to the snowmobile moving too fast. At the same time, multi-sensor fusion avoids false triggering of the trigger signal; the vibration sensor provides high sensitivity and foresight for the trigger signal generating device, so that the trigger signal generating device does not need to be arranged too far away from the laser array, reducing the transmission time delay with the laser array. Specifically, the vibration sensor can enable the system to enter a high-precision capture state in advance, reducing software and hardware overhead while effectively avoiding capture loss.

[0071] 103) After the laser array enabling component receives the trigger signal, the laser array starts sampling until the snowmobile leaves the laser array. The data output by the laser array is a binary tuple: (t, D), where t is the sampling timestamp and D is the distance matrix, which is defined as follows:

[0072]

[0073] The size of the laser array is m*n, and the bobsleigh attitude matrix Q can be obtained after filtering.

[0074] Step 2) trajectory coordinate calculation is to process the output of step 1) two-tuple (t, D) to obtain the snowmobile trajectory coordinate two-tuple (t, Pos), specifically:

[0075] 201) Pos is the coordinate matrix of the snow vehicle trajectory at time t, which is defined as follows:

[0076]

[0077] where x i is the x-axis coordinate calculated by the cross section of the i-th laser array, y i is the y-axis coordinate calculated by the cross section of the i-th laser array, z i is the z-axis coordinate calculated from the i-th laser array cross section, 1≤i≤m;

[0078] When the snowmobile passes through the laser array, a cross-sectional curve of the snowmobile is obtained, and the curve is converted into a polygon by simplifying the curve into a straight line.

[0079] 202) After obtaining the posture matrix Q, the centroid of the polygon formed by the posture matrix Q is calculated;

[0080] 203) x in the Pos matrix i The coordinates are determined by the installation position of the laser array and the calculation rules are as follows:

[0081]

[0082] Among them, offset is along the track axis x i The offset distance relative to x1, x1 is the x-axis coordinate of the first row of laser nodes, its value is 0, x i is the x-axis coordinate of the laser node row numbered i;

[0083] 204) According to the installation position of each laser node in the laser matrix, determine the L matrix, which is defined as follows:

[0084]

[0085] l i,j Represents the y-coordinate of the laser node numbered (i, j); for the laser node numbered (i, j), its coordinate value is (x i ,l ij ,0);1≤i≤m,1≤j≤n;

[0086] 205) For the Pos matrix (y i ,z i ), calculated using the following formula:

[0087]

[0088]

[0089]

[0090] Where A is an intermediate variable in the calculation process, representing the area of ​​the polygon approximating the cross section of the snowmobile, n is the number of laser array rows, d i，j The ranging result returned by the laser ranging node numbered (i, j);

[0091] At this point, the solution of the Pos matrix is ​​completed, and the trajectory of the snowmobile and the binary (t, D) are obtained.

[0092] Step 3) Complete the snowmobile speed data calculation:

[0093] 301) For the speed tuple The speed of the snowmobile at time t is:

[0094]

[0095] Mean represents the mean operation, Pos t is the snowmobile trajectory matrix at time t, Pos t-1 is the previous snowmobile trajectory matrix at the adjacent t time, Δt is Pos t With Pos t-1 The time interval between two sampling calculations;

[0096] 302) Using the Mean function to calculate the mean value of the matrix column, the speed v of the snowmobile is:

[0097]

[0098] in is the speed of the bobsleigh.

[0099] Step 4) achieves real-time visualization by performing a thread transformation on the Pos matrix to Pos′, where the Pos′ coordinate system is the 3D track model coordinate system. The calculation formula is as follows:

[0100] Pos'=RPos

[0101] Where R is the rotation matrix. After completing coordinate system 1, the bobsleigh's posture, trajectory, and speed information can be rendered at key corners on the track model. Because the calculation methods in steps 2) and 3) are vectorized and implemented on a professional hardware platform, real-time visualization is guaranteed. Coaches use this visualization and the digital twin results to analyze cornering posture, trajectory, and speed, as well as exit posture, trajectory, and speed, helping athletes improve their skating skills and competitive performance.

[0102] Step 5) is to establish a cornering evaluation model; cornering time is the indicator that athletes and coaches are most concerned about. After the above collection process, the evaluation parameters that affect the cornering time score are calculated, including: track length len, cornering entry angle deg_in, cornering exit angle deg_out, maximum cornering speed v_max, minimum cornering speed v_min, and average cornering speed v_avr. The cornering entry angle deg_in and cornering exit angle deg_out are calculated based on the curvature of the track curve. The cornering evaluation model uses the Pearson correlation coefficient to quantify the correlation between the score and each evaluation parameter, so that athletes can conduct targeted training to reduce cornering time.

[0103] like Figure 2 The following figure shows the hardware components of the present invention. When the bobsleigh is under the laser array, the laser array outputs the distance between each laser node and the bobsleigh surface. The programmable logic gate array is responsible for bobsleigh posture acquisition, trajectory calculation, and speed calculation. The host computer is responsible for visualization and cornering evaluation modeling.

[0104] like Figure 3 As shown, the software components of the present invention include posture acquisition and trajectory speed calculation components running on the programmable logic gate array, and real-time visualization components and cornering evaluation model components running on the host computer.

[0105] like Figure 4 The cross section of the hardware structure of the present invention is shown in FIG. There are n laser nodes in the cross section, which return n measurement results and are the components of the laser array yOz surface structure.

[0106] like Figure 5 The figure shows a three-dimensional diagram of the hardware structure of the present invention. The figure defines the complete three-dimensional coordinate system of the laser array; the signal trigger device needs to be placed closer to the starting point than the laser array.

[0107] The method of the present invention describes a forward triggering method in step 1), which can quickly start the laser array to avoid missing high-speed moving bobsleigh and snowmobile, reduce the power consumption of the laser array system, and increase the life of the laser array system; the forward triggering device has the characteristics of strong fault tolerance and high sensitivity.

[0108] Hardware-accelerated parallel processing of the laser rangefinder array's output matrix data is implemented on a field-programmable gate array (FPGA), improving the system's real-time performance. Steps 2 and 3 describe methods for calculating the bobsleigh's trajectory coordinates from the posture data. Based on this, a method for calculating the bobsleigh's velocity from the trajectory coordinates was designed, completing the unified calculation of posture, trajectory, and velocity, achieving complete synchronization among the three. A key aspect of the trajectory calculation method is the approximation of the bobsleigh's cross-section using straight lines instead of curved lines.

[0109] In step 5), a cornering evaluation model was established to quantify the impact of various factors on cornering time; this model can help coaches and athletes find training focus, pass corners safely and quickly, and achieve precise cornering.

[0110] The method of the present invention can achieve centimeter-level positioning accuracy, fully parallelize the laser ranging array data processing, and has high real-time performance; it can simultaneously obtain the posture, trajectory, and speed of the bobsleigh, fundamentally avoiding the defect of inconsistency among the three pieces of information.

Claims

1. A method for visualizing posture and trajectory of precise cornering in competitive bobsleigh, characterized by The following steps are involved: 1) Determine whether a trigger signal is received. If a trigger signal is received, it means that a snowmobile has appeared, and the laser array begins to collect data until the snowmobile leaves the laser array; 2) Calculate the track coordinates: process the output tuple (t, D) in step 1) to obtain the track coordinate tuple (t, Pos); 3) Calculation of bobsleigh speed data; 4) Real-time visualization: linear transformation of the Pos matrix is ​​performed. After completing the coordinate system, the bobsleigh’s posture, trajectory, and speed information are rendered to the key corners of the track model to ensure real-time visualization. 5) Establish a cornering evaluation model. After the above data collection process, the evaluation parameters that affect the cornering time score are calculated. The cornering evaluation model uses the Pearson correlation coefficient to quantify the correlation between the score and each evaluation parameter, so that athletes can conduct targeted training to reduce cornering time. Step 2) trajectory coordinate calculation is to process the output of step 2) two-tuple (t, D) to obtain the snowmobile trajectory coordinate two-tuple (t, Pos), specifically: 201) Pos is the coordinate matrix of the snow vehicle trajectory at time t, which is defined as follows: where x i is the x-axis coordinate calculated by the cross section of the i-th laser array, y i is the y-axis coordinate calculated by the cross section of the i-th laser array, z i is the z-axis coordinate calculated from the i-th laser array cross section, 1≤i≤m; When the snowmobile passes through the laser array, a cross-sectional curve of the snowmobile is obtained, and the curve is converted into a polygon by simplifying the curve into a straight line. 202) After obtaining the posture matrix Q, the centroid of the polygon formed by the posture matrix Q is calculated; 203) x in the Pos matrix i The coordinates are determined by the installation position of the laser array and the calculation rules are as follows: Among them, offset is along the track axis x i The offset distance relative to x1, x1 is the x-axis coordinate of the first row of laser nodes, its value is 0, x i is the x-axis coordinate of the laser node row numbered i; 204) According to the installation position of each laser node in the laser matrix, determine the L matrix, which is defined as follows: l i,j Represents the y-coordinate of the laser node numbered (i, j); for the laser node numbered (i, j), its coordinate value is (x i ,l ij ,0);1≤i≤m,1≤j≤n; 205) For the Pos matrix (y i ,z i ), calculated using the following formula: Where A is an intermediate variable in the calculation process, representing the area of ​​the polygon approximating the cross section of the snowmobile, n is the number of laser array rows, d i，j The ranging result returned by the laser ranging node numbered (i, j); At this point, the solution of the Pos matrix is ​​completed, and the trajectory of the snowmobile and the binary (t, D) are obtained.

2. The method for visualizing posture and trajectory for precise cornering in competitive bobsleigh according to claim 1, characterized in that: Step 1) is specifically as follows: 101) A trigger signal generating device is arranged in front of the laser array; 102) generating a trigger signal by a trigger signal generating device; 103) After the laser array enabling component receives the trigger signal, the laser array starts sampling until the snowmobile leaves the laser array. The data output by the laser array is a binary tuple: (t, D), where t is the sampling timestamp and D is the distance matrix, which is defined as follows: The size of the laser array is m*n, and the bobsleigh attitude matrix Q can be obtained after filtering.

3. The method for visualizing posture and trajectory for precise cornering in competitive bobsleigh according to claim 2, characterized in that: The trigger signal generating device integrates a vibration sensor, a Hall sensor and a light curtain sensor.

4. The method for visualizing posture and trajectory for precise cornering in competitive bobsleigh according to claim 1, characterized in that: Step 3) Calculate the snowmobile speed data as follows: 301) For the speed tuple The speed of the snowmobile at time t is: Mean represents the mean operation, Pos t is the snowmobile trajectory matrix at time t, Pos t-1 is the previous snowmobile trajectory matrix at the adjacent t time, Δt is Pos t With Pos t-1 The time interval between two sampling calculations; 302) Using the Mean function to calculate the mean value of the matrix column, the speed v of the snowmobile is: in is the speed of the bobsleigh.

5. The method for visualizing posture and trajectory for precise cornering in competitive bobsleigh according to claim 1, characterized in that: Step 5) The evaluation parameters that affect the cornering time score include: track length len, cornering entry angle deg_in, cornering exit angle deg_out, maximum cornering speed v_max, minimum cornering speed v_min, and average cornering speed v_avr; where the cornering entry angle deg_in and cornering exit angle deg_out are calculated based on the curvature of the track curve.

6. The method for visualizing posture and trajectory for precise cornering in competitive bobsleigh according to claim 1, characterized in that: In step 4), the Pos matrix is ​​transformed into Pos′ through threading. The Pos′ coordinate system is the three-dimensional track model coordinate system. The calculation formula is as follows: Pos'=RPos Where R is the rotation matrix.

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