A method and device for controlling the coordination of a kayaker's power output

Abstract

The application provides a kayak athlete power output coordination control method, comprising: collecting the paddle water entry depth, the angle of attack deflection angle, the athlete power time and the hull acceleration, obtaining the complete record containing the paddle track arc and the hull acceleration change; according to the change of the straight line track and the arc track when the hull accelerates, the angle of attack deflection angle is extracted, the deviation degree of the angle of attack deflection angle and the effective propulsion angle range is evaluated, and the proportion of energy loss caused by the lateral component force under different deviation degrees is identified; according to the power output timing coordination score, the smoothness of the power transmission among the athlete, the paddle and the hull is analyzed, and the stability of the transmission efficiency in the acceleration stage is identified after removing the interference signal; according to the track optimization direction adjustment training system collection setting, the track optimization direction is returned to the collection density adjustment link, and the time interval setting of the next data collection is determined.

Description

Technical Field

[0001] This invention relates to the field of information technology, and in particular to a method and device for controlling the coordination of power output of rowing athletes. Background Technology

[0002] Rowing, a competitive sport demanding high levels of strength and coordination, hinges on how athletes efficiently propel the boat forward through paddling motions. Research in this area is crucial for improving athlete performance and optimizing training methods, directly impacting breakthroughs in competition results and technological innovation. For a long time, researchers have been dedicated to exploring the optimal match between paddling motion and boat motion to achieve higher propulsion efficiency and more stable speed. However, existing methods for analyzing rowing propulsion efficiency often overlook the complex dynamic impact of boat speed changes on paddling motion. Many traditional views focus solely on whether the paddle trajectory is close to a straight line, arguing that a straight trajectory reduces water resistance, without fully considering the effects of instantaneous acceleration or deceleration of the boat during paddling. This one-sided perspective leads to insufficient understanding of the coordination between paddling motion and boat motion, making it difficult to reveal the deeper issues of power transmission efficiency. The dynamic matching between the shape of the paddle trajectory and boat speed fluctuations has not yet been effectively resolved. The shape of the paddle trajectory, as a key factor affecting propulsion efficiency, directly determines the attitude of the paddle blades in the water and the direction of power transmission. If the paddle trajectory cannot adjust in time with changes in boat speed, it will cause the paddle blades to deviate from the direction of the water flow, generating ineffective lateral force and thus reducing overall propulsion. For example, during the acceleration phase, if the paddle trajectory remains too rigidly straight, the blade angle will not adapt to changes in the water flow, resulting in wasted power and even affecting boat stability. This contradiction between trajectory shape and speed fluctuations has become a core obstacle hindering the optimization of rowing technique. Therefore, how to dynamically adjust the paddle trajectory shape according to real-time changes in boat speed during rowing to ensure efficient power transfer and coordinated movements has become a key issue in the analysis and optimization of power output for rowing athletes. Summary of the Invention

[0003] This invention provides a method for controlling the coordination of power output in rowing athletes, mainly comprising: Acquire three-dimensional coordinate data of the propeller blades moving underwater and hull acceleration data, and generate a record containing the changes in the radii of the propeller blade trajectory and the hull acceleration. Based on the records, the morphological features of the propeller trajectory are extracted, the straight trajectory and the arc trajectory are distinguished, and the accompanying changes of the straight trajectory and the arc trajectory during the acceleration of the ship are determined. The deviation between the blade angle of attack deflection and the propulsion angle range is analyzed by the accompanying changes, and the proportion of energy loss caused by the lateral force is calculated. Based on the energy loss ratio and the athlete's exertion time, the time deviation between the exertion time and the peak acceleration is evaluated to generate a power output timing coordination score. The smoothness of force transmission is analyzed by the coordination score, and the stability of transmission efficiency during the acceleration phase is identified. Based on the stability of the transmission efficiency, a coordination report is generated to assess the differences in propulsion angle maintenance among different trajectory morphologies and determine the direction of trajectory optimization.

[0004] Furthermore, the acquisition of three-dimensional coordinate data of the propeller blade's underwater motion and hull acceleration data, and the generation of a record containing the propeller blade trajectory radii and hull acceleration changes, includes: The three-dimensional coordinate sequence of the propeller blades is obtained by an underwater camera device, and the depth of the propeller blades entering the water is calculated. The pressure change curve of the paddle handle is obtained from the force sensor to identify the moment when the athlete exerts force. The instantaneous acceleration of the ship is calculated based on the three-dimensional coordinate sequence. If the rate of change of acceleration exceeds a preset threshold, the data acquisition time interval is adjusted. By resampling the three-dimensional coordinate sequence and pressure change curve at adjusted time intervals, the blade position sequence under different sampling densities can be obtained. The angle of attack deflection is calculated based on the blade position sequence, and the blade trajectory arc curve is obtained by fitting. The entry depth, angle of attack deflection, moment of force application, and hull acceleration values ​​are matched to form a complete record.

[0005] Furthermore, the step of extracting the blade trajectory morphology features based on the records, distinguishing between straight trajectories and curved trajectories, and determining the accompanying changes of the straight trajectories and curved trajectories during ship acceleration includes: Read the three-dimensional coordinate points of the blade from the record and calculate the angle between the vectors of adjacent coordinate points; If the angle between the vectors of adjacent coordinate points deviates from the horizontal angle by more than a preset radian threshold, it is marked as an arc-shaped trajectory point; otherwise, it is marked as a straight trajectory point. The trajectory is segmented based on a sequence of continuously marked coordinate points; Extract the numerical sequence of ship acceleration for the corresponding time period from the records, calculate the magnitude of acceleration change during the straight trajectory segment and the arc trajectory segment, and determine the accompanying change characteristics of the straight trajectory and the arc trajectory during ship acceleration.

[0006] Furthermore, the step of analyzing the deviation between the blade angle of attack deflection and the propulsion angle range through the accompanying changes, and calculating the proportion of energy loss caused by the lateral force, includes: The blade angle of attack value is read based on the accompanying changes, compared with the preset propulsion angle range, and the difference between the angle of attack and the center value is calculated. If the difference between the angle of attack and the center value exceeds a preset threshold, it is determined to be a deviation state, and the time and angle value of the deviation are recorded. The thrust projection component and lateral component are calculated using the angle of attack value at the deviation time, and the response delay time is obtained based on the component ratio. The average response delay time under different trajectory patterns was statistically analyzed to determine the adaptability index; The instantaneous energy loss rate is calculated based on the proportion of the lateral component, and the average loss rate is statistically calculated according to the deviation angle interval.

[0007] Furthermore, the step of assessing the time deviation between the moment of force exertion and the peak acceleration based on the energy loss ratio and the athlete's force exertion time, and generating a force output timing coordination score, includes: Read the loss value sequence from the energy loss ratio and extract the power generation start timestamp; The peak acceleration time point is identified by differential operation on the hull acceleration sequence, and the time difference between the force exertion start time stamp and the peak time point is calculated. The degree of synchronization is determined based on the time difference, the frequency of occurrence of different degrees of synchronization is counted, and the proportion of highly synchronized states is calculated as the synchronization score. The rigidity of the trajectory is assessed based on the variance of the blade angle within the straight trajectory segment, and the correlation between the variance and the proportion of energy loss is calculated to obtain the influence coefficient. The final coordination score is calculated using the synchronicity score and the influence coefficient.

[0008] Furthermore, the step of analyzing the smoothness of force transmission through the coordination score and identifying the stability of transmission efficiency during the acceleration phase includes: Based on the coordination score, divide the interval and read the athlete's force curve, propeller propulsion curve, and boat speed curve. Calculate the rate of change of the curve values, and after time alignment, calculate the phase difference value to obtain the power transmission smoothness index. Interference signals are identified and removed through filtering, and the ratio of the variance of the data before and after filtering is calculated as the smoothness. The transmission characteristic value is determined based on the smoothness index and smoothness. The start and end times of the acceleration phase are identified by the feature value sequence, the instantaneous transmission efficiency is calculated, and the stability of the transmission efficiency is determined based on the standard deviation of the efficiency sequence.

[0009] Furthermore, based on the aforementioned transmission efficiency stability, a coordination report is generated to assess the differences in propulsion angle maintenance among different trajectory morphologies and determine the trajectory optimization direction, including: A coordination report is generated based on the aforementioned transmission efficiency and stability indicators; Extract the effective propulsion angle retention rate of the arc trajectory and the straight trajectory from the coordination report, calculate the difference between the two and obtain the comparison results; The lateral force loss ratio for the corresponding time period is used as an energy loss indicator by comparing the results. If the retention rate of the arc-shaped trajectory is higher than that of the straight-line trajectory and the loss index is lower than the preset threshold, then the arc-shaped trajectory is determined as the recommended trajectory shape; otherwise, the straight-line trajectory is determined as the recommended trajectory shape, and the trajectory optimization direction is obtained.

[0010] Furthermore, the method also includes: adjusting the data acquisition settings according to the trajectory optimization direction to determine the next acquisition time interval.

[0011] Furthermore, based on the trajectory optimization direction, the data acquisition settings are adjusted to determine the next acquisition time interval, including: Key areas are collected based on the recommended trajectory shape mapping in the trajectory optimization direction; If an arc-shaped trajectory is recommended, then set the sampling frequency of the arc segment to twice the standard frequency; If a straight line trajectory is recommended, the sampling frequency of the straight line segment is set to twice the standard frequency to obtain a differentiated acquisition configuration; The differentiated acquisition configuration is transmitted to the acquisition density adjustment module via control signals. The specific time interval is calculated based on the frequency multiple relationship to determine the time interval setting for the next data acquisition.

[0012] The technical solutions provided by the embodiments of the present invention may include the following beneficial effects: This invention discloses a method and device for controlling the coordination of force output in rowing athletes. Addressing the core business scenario of the impact of paddle trajectory morphology on force transmission efficiency and boat stability in rowing, this invention dynamically adjusts data acquisition density and combines underwater cameras and force sensors to acquire key data such as paddle entry depth, angle of attack deflection, and boat acceleration in real time. By analyzing the paddle trajectory curvature and acceleration changes, this invention distinguishes between straight and curved trajectories, assesses the impact of angle of attack deflection on propulsion efficiency, identifies energy loss caused by lateral force components, and combines the synchronization of the athlete's force application timing and peak acceleration to generate a force output timing coordination score. Finally, a coordination report is generated, proposing the optimal trajectory morphology to avoid force waste and maintain boat stability. This invention uses a feedback loop to transmit the optimized direction back to the data acquisition settings, achieving adaptive adjustment and significantly improving the accuracy and efficiency of the training system. Attached Figure Description

[0013] Figure 1 This is a flowchart of a method for controlling the coordination of power output in rowing athletes according to the present invention. Detailed Implementation

[0014] The technical solutions of the embodiments of the present invention will be clearly and thoroughly described below with reference to the accompanying drawings. The described embodiments are merely some embodiments of the present invention.

[0015] Example 1: like Figure 1 This embodiment of a method for controlling the coordination of power output in rowing athletes may specifically include: S101. Collect the blade entry depth, angle of attack deflection, moment of the athlete's exertion, and hull acceleration to obtain a complete record including the blade trajectory arc and changes in hull acceleration.

[0016] Three shooting angles are set before and after the blade's entry point into the water using an underwater camera device to acquire a three-dimensional coordinate sequence of the blade's underwater motion. The depth of the blade relative to the horizontal plane is calculated based on the vertical coordinate difference between adjacent points in the coordinate sequence. Simultaneously, the pressure change curve at the propeller handle is read from a force sensor, and the moment with the largest slope of the pressure curve is identified as the moment the athlete exerts force. The instantaneous acceleration of the hull is calculated based on the three-dimensional coordinate sequence, and the rate of change of acceleration is calculated as (a...). t+1 -a t ) / Δt, where a is the acceleration and Δt is the time interval. If the rate of change exceeds the threshold of 2 m / s 3 If the rate of change is less than the threshold, the data acquisition interval is shortened to half of the original interval. If the rate of change is less than the threshold, the standard acquisition interval of 0.02 seconds is maintained. The three-dimensional coordinate sequence and pressure change curve are resampled using the adjusted time interval to obtain the blade position sequence under different acquisition densities. Trajectory points are extracted from the blade position sequence and cubic spline interpolation is performed. This interpolation uses the trajectory points as input and natural boundary conditions as parameters. A piecewise polynomial function is used to fit a smoothly connected blade trajectory curvature curve. The water depth, angle of attack deflection, power generation time marker, and hull acceleration value at each sampling time are matched to obtain a complete record containing the changes in blade trajectory curvature and hull acceleration.

[0017] Specifically, in one implementation, the underwater camera device employs high-speed waterproof cameras, installed at three positions on the bottom of the rowing boat: front, side, and rear. Each camera captures the paddle movement at 120 frames per second. Using triangulation, the two-dimensional image information from the three angles is fused into the three-dimensional spatial coordinates of the paddle. Each coordinate point includes three components: X-axis lateral position, Y-axis longitudinal position, and Z-axis vertical height. The vertical height component directly reflects the paddle's depth relative to the water surface; a negative Z-axis coordinate indicates the paddle is underwater, and its absolute value is the actual depth. A force sensor is installed at the connection between the paddle handle and the athlete's grip, sampling at a frequency of 500 Hz, accurately capturing subtle changes in the athlete's force application. The slope of the pressure curve is calculated by dividing the pressure difference between two adjacent sampling points by the time interval, specifically k = (P2 - P1) / Δt, where k is the slope, P1 and P2 are adjacent pressure values, and Δt is the time interval of 0.002 seconds. When k suddenly increases from less than 0.1 to a peak value greater than 5 within 0.01 seconds, this moment is marked as the athlete's main exertion point by comparing three consecutive k values. This moment corresponds to the critical node where the paddle blades begin to generate maximum propulsion force on the water. The calculation of the hull acceleration is based on the position change of the hull reference point in the three-dimensional coordinate sequence. The instantaneous acceleration value is obtained through the finite difference method. The input is the position sequence x(t), and the output is a = (x(t + 2Δt) - 2x(t + Δt) + x(t)) / (Δt). 2 Δt represents the time step. When the rate of change of acceleration exceeds a set threshold, the acquisition interval is automatically shortened from the standard 0.02 seconds to 0.01 seconds, thereby capturing denser data points during periods of rapid change in boat speed and ensuring that no key motion details are missed. By synchronously integrating camera coordinates, force data, and acceleration sequences, a complete record of the athlete's paddling cycle is formed.

[0018] In one embodiment, the angle of attack deflection characterizes the change in the angle between the blade plane and the longitudinal axis of the hull, which directly affects the direction of the water flow's effect on the blade. By calculating the angle between the vector formed by adjacent sampling points and the hull's forward direction, the blade's attitude adjustment at each moment can be quantified. The specific calculation process is as follows: Let the vector formed by adjacent sampling points be A, and the vector of the hull's forward direction be B. Then, the angle θ is calculated using the formula θ=arccos((A·B) / (|A||B|)), where A·B is the vector dot product, and |A| and |B| are the vector magnitudes, respectively. Cubic spline interpolation is used to smoothly connect discrete trajectory points, generating a continuous and smooth trajectory arc curve. This curve not only retains the positional information of the original sampling points but also supplements the motion details within the sampling interval through the interpolation algorithm, making the analysis of the trajectory morphology more accurate.

[0019] Preferably, the complete record is stored using a time-series data structure, with each timestamp corresponding to a set of four-dimensional vectors containing water depth, angle of attack deflection, force marker, and acceleration. This structured storage method facilitates subsequent analysis of the dynamic correlation between the propeller trajectory morphology and the ship's motion state.

[0020] S102. Extract the magnitude of the blade trajectory radii from the complete record of the changes in the hull acceleration, identify the differences in trajectory radii to distinguish between straight trajectories and curved trajectories, and determine the accompanying changes of straight trajectories and curved trajectories during hull acceleration.

[0021] The three-dimensional coordinates of the propeller blades at each sampling moment are read from the complete record. The trajectory shape is determined by calculating the angle between the two vectors formed by three adjacent coordinate points. If the angle deviates from the horizontal angle by more than a preset threshold of 0.1 radians, the point is marked as an arc trajectory point; otherwise, it is marked as a straight trajectory point. Coordinate points with the same label are defined as a continuous sequence of the same trajectory type, and each trajectory segment is statistically obtained. Based on the time range of the trajectory segments, the corresponding ship acceleration value sequence is extracted from the complete record. The change amplitude of acceleration value during the straight trajectory segment and the change amplitude of acceleration value during the arc trajectory segment are calculated, and the accompanying change characteristics of the straight trajectory and arc trajectory during ship acceleration are determined accordingly.

[0022] Specifically, in one implementation, when reading the three-dimensional coordinate points of the propeller blade one by one from the complete record, each coordinate point contains timestamp information and spatial location information. Three adjacent coordinate points form two vectors, and the cosine value of the angle between these two vectors is calculated using the vector dot product formula. Then, the actual angle is obtained using the inverse cosine function.

[0023]

[0024] This is the formula for calculating a vector composed of adjacent coordinate points. v1 represents the first vector, P1 and P2 represent two adjacent coordinate points, x1, y1, and z1 represent the coordinate components of the first point, and x2, y2, and z2 represent the coordinate components of the second point. The vector components are obtained by subtracting the starting point coordinates from the ending point coordinates.

[0025]

[0026] This is the core formula for calculating the cosine of the angle between two vectors. θ represents the angle between two vectors, a and b represent the two vectors, a·b represents the vector dot product, and |a| and |b| represent the magnitudes of the two vectors, respectively. x a y a z Let b represent the three components of vector a. x b y bz The three components of vector b are represented by the cosine of the included angle, which is obtained by dividing the dot product by the product of the magnitudes.

[0027]

[0028] This is a formula for converting cosine values ​​into actual angles using the inverse cosine function. θ represents the final angle, u and v represent two vectors, arccos represents the inverse cosine function, u·v represents the vector dot product, |u| and |v| represent the vector magnitudes, and 180 / π is the conversion coefficient from radians to degrees. The preset radian threshold for obtaining the angle value in degrees is set to 15 degrees. When the difference between the calculated angle and 180 degrees exceeds this threshold, it indicates that the blade trajectory has significant curvature, and this coordinate point is marked as an arc-shaped trajectory point. A continuous sequence of arc-shaped trajectory points constitutes an arc-shaped trajectory segment, and a continuous sequence of straight-line trajectory points constitutes a straight-line trajectory segment. The accompanying change characteristics are characterized by the amplitude of the acceleration value change, which is calculated using the difference between the maximum and minimum acceleration values ​​within that time period. When the acceleration change amplitude corresponding to the straight trajectory segment is less than 0.5 m / s², it indicates that the straight rowing motion is accompanied by a stable propulsion output; when the acceleration change amplitude corresponding to the arc trajectory segment is greater than 1.5 m / s², it indicates that the arc rowing motion is accompanied by rapid acceleration and deceleration switching. This accompanying change characteristic directly reflects the impact of different trajectory shapes on the propulsion efficiency of the ship.

[0029] S103. Extract the angle of attack deflection angle based on the accompanying changes of the straight trajectory and arc trajectory during hull acceleration, assess the degree of deviation between the angle of attack deflection angle and the effective propulsion angle range, and identify the proportion of energy loss caused by the lateral component force under different degrees of deviation.

[0030] The blade angle of attack values ​​are read at various moments based on the accompanying changes in straight and curved trajectories during ship acceleration. These values ​​are compared with a preset effective propulsion angle range of -15 to +15 degrees. The absolute difference between the blade angle of attack value and the zero-degree center value is calculated. If the difference exceeds 15 degrees, a deviation is identified, and the time of deviation, the deviation angle value, and the corresponding trajectory shape marker are recorded. The projected component of the blade propulsion force in the ship's forward direction, Fp=F, is calculated using the angle of attack value at the time of deviation. cos(a) and the lateral component perpendicular to the direction of travel, Fs=F sin(a), where F is the total propulsion force of the blade and a is the angle of attack at the deviation time; the response delay time tau is calculated based on the ratio of the lateral component to the projected component = sampling time interval / (1 - |lateral component perpendicular to the forward direction / projected component of the propulsion force of the blade in the forward direction of the hull|). This formula is based on a first-order dynamic response model to reflect the true response time of the blade to changes in the water flow; for each trajectory segment, the response delay time of all deviation times is collected and its mean is calculated. The mean response delay time of all deviation times in the straight trajectory segment and the mean response delay time in the arc trajectory segment are statistically analyzed. The reciprocal of the mean is used as the adaptability index for different trajectory shapes. This index is used to evaluate the response adaptability of the blade under the corresponding trajectory. The lateral force ratio is obtained by dividing the lateral component by the total propulsion force of the blade. The lateral force ratio is used as the instantaneous energy loss rate. According to the deviation angle value, it is divided into three intervals: less than 5 degrees, 5 to 10 degrees, and greater than 10 degrees. The average loss rate of all sampling times in each interval is calculated to identify the energy loss ratio caused by the lateral force under different deviation degrees.

[0031] Specifically, in one implementation, the effective propulsion angle range is set based on fluid dynamics principles. When the blade angle of attack is maintained within the range of -15 degrees to +15 degrees, the water flow can smoothly flow along the blade surface, forming a stable propulsion force. Beyond this range, vortex separation occurs on the back of the blade, leading to a sharp decrease in propulsion efficiency. When reading the angle of attack value, data is collected every 0.01 seconds by an angle sensor installed on the blade and compared in real time with the preset range.

[0032] Specifically, the propulsion decomposition process involves vectoring the total propulsion generated by the propeller blades according to the angle of attack. When the angle of attack is zero degrees, all propulsion acts in the direction of the ship's forward movement; when the angle of attack deviates from zero degrees, the propulsion is decomposed into an effective component in the forward direction and a lateral component perpendicular to the forward direction. The lateral component not only fails to contribute to propulsion but also causes lateral swaying of the hull, affecting navigation stability. The response delay time is calculated by multiplying the ratio of the lateral component to the effective component by the sampling time interval. This time reflects the reaction time required for the propeller blades to adjust their attitude to adapt to changes in the water flow. The adaptability index is characterized by the reciprocal of the mean response delay time; a larger value indicates a stronger adaptability of the trajectory shape to changes in the water flow. In a straight trajectory, due to the small change in propeller attitude, the response delay time is usually below 0.05 seconds; while in an arc trajectory, because the propeller blades need to continuously adjust the angle of attack, the response delay time may reach more than 0.1 seconds, resulting in a significant decrease in the adaptability index.

[0033] Preferably, the division of deviation ranges takes into account the impact of different deviation angles on energy loss. Deviations of less than 5 degrees fall within the normal fluctuation range, with energy loss rates typically below 10%; deviations of 5 to 10 degrees generate significant lateral forces, increasing the loss rate to 15% to 25%; deviations greater than 10 degrees enter the stall region, where the loss rate may exceed 30%. By statistically analyzing the average loss rate within each range, the impact of different paddling techniques on propulsion efficiency can be quantitatively assessed.

[0034] In one embodiment, an athlete used an arc-shaped paddling trajectory during the acceleration sprint phase, with the angle of attack frequently deviating by more than 10 degrees. This resulted in the lateral force accounting for 35% of the total propulsion, severely impacting acceleration. By adjusting to a straight trajectory and controlling the angle of attack to within 5 degrees, the energy loss rate was reduced to 8%, and acceleration performance was significantly improved.

[0035] S104. Based on the proportion of energy loss caused by lateral force and the athlete's exertion time, analyze the synchronicity between the exertion time and the peak acceleration of the ship, evaluate the time deviation between the exertion time and the peak acceleration, and obtain the power output timing coordination score.

[0036] The energy loss sequence at each sampling moment is read based on the proportion of energy loss caused by the lateral force. The start time stamp of the force exertion is extracted from the athlete's force exertion time marker. The peak acceleration time point is identified by performing differential operations on the boat acceleration sequence. The time difference between the start time stamp of the force exertion and the peak acceleration time point is calculated to obtain the synchronization index of force exertion and acceleration. The degree of synchronization is judged by the absolute value of the time difference. When the time difference is less than 0.05 seconds, it is recorded as highly synchronized; 0.05 to 0.1 seconds is recorded as moderately synchronized; and greater than 0.1 seconds is recorded as out-of-synchronization. The frequency of each synchronization level in the entire paddling cycle is counted, and the proportion of highly synchronized states is calculated as the synchronization score. The stiffness of the trajectory is evaluated based on the variance of the blade angle within the straight trajectory segment. The smaller the variance value, the stiffer the trajectory. The correlation between the variance value and the energy loss proportion of the corresponding time period is calculated to obtain the influence coefficient of the stiff trajectory on the power transmission efficiency. The synchronicity score is multiplied by 100 to obtain the base score. The base score is then reduced according to the influence coefficient. If the influence coefficient is greater than 0.3, 30 points are reduced; if it is between 0.1 and 0.3, 15 points are reduced; and if it is less than 0.1, no reduction is made to obtain the force output timing coordination score.

[0037] Specifically, in one implementation, reading the loss value sequence involves continuously recording the percentage of energy loss at each sampling moment to form time-series data. This sequence reflects the energy waste caused by blade angle deviation during paddling; a larger value indicates lower propulsion efficiency at that moment. The motive force start time stamp is determined by detecting abrupt changes in the pressure sensor signal. When the pressure value increment between two consecutive sampling points exceeds three times the average increment of the previous period, that moment is marked as the motive force start point.

[0038] Specifically, the differential calculation of the ship's acceleration sequence uses the central difference method. For the acceleration value a(t) at time t, the rate of change of acceleration is calculated by dividing a(t+1) - a(t-1) by twice the sampling interval. When the rate of change changes from a positive value to a negative value, it indicates that the acceleration has reached a local maximum, and this moment is the peak acceleration time point. This method can accurately capture the inflection point of the acceleration curve and avoid misjudgment caused by noise interference. The time difference is obtained by subtracting the force-generating start timestamp from the peak time point. A positive value indicates that the force generation precedes the acceleration peak, and a negative value indicates that the force generation lags behind the acceleration peak. The absolute value reflects the degree of delay in force transmission. The three-level classification of synchronization is based on the statistical analysis of a large amount of experimental data. In the highly synchronized state, the athlete's force can be immediately converted into ship acceleration, and the force transmission path is smooth; moderate synchronization indicates a slight transmission delay, which may be caused by minor deviations in the blade entry angle or depth; the out-of-synchronization state means that the timing of the force generation is seriously mismatched with the rhythm of the ship's movement, and a large amount of energy is lost during the transmission process. By analyzing the frequency of different levels of synchronization throughout the entire paddling cycle, an athlete's rhythm control ability can be comprehensively assessed.

[0039] In one possible implementation, the assessment of trajectory stiffness is based on the statistical properties of the blade angle sequence. For a straight trajectory segment, the blade angle values ​​of all sampling points within the segment are extracted, and the variance of these angle values ​​is calculated. The variance reflects the degree of dispersion of the angle values ​​around the mean; the smaller the variance, the smaller the angle variation, and the closer the trajectory is to a straight line, exhibiting stiffness. Although this stiff trajectory appears stable, it lacks the ability to flexibly adjust to changes in water flow, causing the blades to fail to maintain an ideal angle of attack and generating additional lateral force. The correlation calculation uses the Pearson correlation coefficient method, matching the variance sequence of trajectory stiffness with the energy loss percentage sequence for the corresponding time period. The formula for calculating the Pearson correlation coefficient r is r = cov(X,Y) / (σX). σX and σY are the covariances of X and Y, respectively, and the standard deviations of X and Y are the standard deviations of X and Y, respectively. The specific steps are: first, calculate the mean of the two sequences; then, calculate the covariance and standard deviation; finally, substitute these values ​​into the formula. The absolute value of the correlation coefficient reflects the strength of the association between the two sequences. A positive correlation indicates that the more rigid the trajectory, the greater the energy loss, while a negative correlation has the opposite effect. When the absolute value of the correlation coefficient is greater than 0.7, a strong correlation is considered, and the absolute value of the correlation coefficient is used as the influence coefficient. When the absolute value of the correlation coefficient is between 0.3 and 0.7, the influence coefficient is taken as 0.8 times the absolute value of the correlation coefficient. When it is less than 0.3, the correlation is considered weak, and the influence coefficient is taken as 0.1. This segmented processing method can more accurately reflect the actual impact of rigid trajectories on the efficiency of force transmission.

[0040] For example, the calculation of the synchronization score involves quantifying the proportion of highly synchronized states. If, out of 100 sampling moments, 60 moments are in a highly synchronized state, 25 moments are in a moderately synchronized state, and 15 moments are out of sync, then the proportion of highly synchronized states is 60%, and the synchronization score is 60 points. This score directly reflects the accuracy with which the athlete grasps the timing of their power exertion.

[0041] Understandably, using a percentage system for the base score facilitates understanding and comparison. Multiplying the synchronicity score by 100 yields a base score ranging from 0 to 100, representing the theoretical level of coordination without considering the impact of trajectory stiffness. The reduction rule is designed to account for the weakening effect of the influence coefficient on actual coordination; a larger influence coefficient indicates a more severe negative impact from stiff trajectories, requiring a greater reduction in score.

[0042] For example, a rower's synchronization score during training was 0.75, indicating that he was in a highly synchronized state 75% of the time, with a base score of 75. Simultaneously, the angular variance of the straight trajectory segment was detected to be 2.3 degrees², with a correlation coefficient of 0.45 with the energy loss percentage, determining an influence coefficient of 0.36. According to the reduction rule, an influence coefficient greater than 0.3 requires a reduction of 30 points, resulting in a power output timing coordination score of 45. This indicates that although the timing of force exertion was relatively good, the rigid paddling trajectory severely affected power transfer efficiency. Furthermore, this scoring mechanism can help coaches identify the key technical problems of athletes. A high synchronization score combined with a low coordination score indicates that the problem mainly lies in overly rigid trajectory control; a low synchronization score indicates a need to focus on training the timing of force exertion. Through regular evaluation and comparison, the effectiveness of technical improvements can be tracked, providing a quantitative basis for adjusting training programs.

[0043] S105. Analyze the smoothness of power transmission among the athlete, the paddle, and the hull based on the power output timing coordination score, and identify the stability of the transmission efficiency during the acceleration phase after eliminating interference signals.

[0044] Based on the power output timing coordination score, the coordination score is divided into three intervals: high, medium, and low. Three sets of time-series data—the athlete's force curve, the propeller propulsion curve, and the boat's speed curve—are read. The rate of change between adjacent moments is calculated. After time alignment of the rate of change sequences of the three curves, the phase difference is calculated. The cosine of the phase difference is used to obtain the power transmission smoothness index. A median filter with a window size of 5 is used to process the three sets of time-series data. Outliers with amplitudes exceeding twice the standard deviation are identified and marked as interference signals. After removing these interference signals, the correlation coefficient ratio of the data before and after filtering is calculated as the smoothness. The purified transmission characteristic value is determined by the weighted sum of the smoothness index and the smoothness. The start and end times of the acceleration phase are identified by abrupt changes in the purified transmission characteristic value sequence. The ratio of the athlete's output power to the boat's acquired power at each moment during the acceleration phase is used as the instantaneous transmission efficiency. The standard deviation of the instantaneous transmission efficiency sequence is used to assess the fluctuation of the transmission process. If the standard deviation is less than a preset threshold, the transmission efficiency is considered stable.

[0045] Specifically, in one implementation, the interval division of the force output timing coordination score uses an equidistant method, dividing the score range of 0 to 100 into a low coordination interval (below 40 points), a medium coordination interval (40 to 70 points), and a high coordination interval (above 70 points). Different intervals correspond to different force transmission characteristics: the low coordination interval indicates severe transmission obstacles, the medium coordination interval has room for improvement, and the high coordination interval represents good transmission performance. The acquisition frequency of the three sets of time series data is consistent, all at 100 Hz. The athlete's force curve is acquired through strain gauge sensors on the paddle handle, reflecting the change in the pulling force applied by the arm; the paddle blade propulsion curve is measured through pressure sensors at the paddle root, recording the force of the paddle blade on the water; and the boat speed curve is recorded in real time by a GPS speed sensor. When calculating the rate of change of values ​​between adjacent moments, the forward difference method is used, subtracting the previous moment's value from the subsequent moment's value and then dividing by the time interval. The rate of change sequence of the three curves reflects the dynamic response characteristics of each link. The time offset that maximizes the correlation coefficient is found through sliding correlation calculation; this offset is the phase difference value. The median filter window size is set to 5 sampling points. For each data point, the median of the five points (two points before and two points after the median) is taken as the filtered output. This method can effectively eliminate impulse interference while preserving the signal's edge characteristics. Smoothness is obtained by calculating the ratio of the signal variance before filtering to the signal variance after filtering. The larger the ratio, the more noise components are in the original signal, and the more obvious the filtering effect.

[0046] Preferably, the purified transmission characteristic values ​​are calculated using a weighted sum method, with the smoothness index weight set to 0.7 and the smoothness index weight set to 0.3. This weight allocation emphasizes both the temporal matching of force transmission and the impact of signal quality. Abrupt point identification is achieved by calculating the first-order difference of the transmission characteristic value sequence and finding points exceeding a threshold. Periods with three or more consecutive abrupt changes are marked as acceleration phases.

[0047] In one embodiment, instantaneous power transfer efficiency is calculated as the ratio of the athlete's output power to the power gained by the boat. The athlete's output power is equal to the product of the force exerted and the propeller speed, while the power gained by the boat is equal to the product of the propulsion force and the boat speed. When the standard deviation of the power transfer efficiency sequence is less than 0.1, the power transfer process is considered stable, indicating that a good power transfer chain has been formed among the athlete, propeller, and boat.

[0048] S106. Generate a coordination report based on the stability of the transmission efficiency during the acceleration phase, evaluate the difference between the arc trajectory and the straight trajectory in maintaining an effective propulsion angle, identify the optimal trajectory shape to avoid wasting power and maintain the stability of the hull, and obtain the trajectory optimization direction.

[0049] Based on the stability values ​​of the transmission efficiency during the acceleration phase, various indicators are compiled into a coordination report. From this report, the ratio of the effective propulsion angle maintenance time to the total time within the arc-shaped trajectory segment is extracted as the arc-shaped trajectory maintenance rate. The same ratio is extracted for the straight-line trajectory segment as the straight-line trajectory maintenance rate. The difference between the two maintenance rates is calculated to obtain the trajectory shape comparison result. Using this trajectory shape comparison result, the proportion of lateral force loss in the corresponding time period is used as the energy loss index. If the arc-shaped trajectory maintenance rate exceeds the straight-line trajectory maintenance rate and the energy loss index is below a preset threshold, the arc shape is determined as the recommended trajectory shape; otherwise, the straight line is determined as the recommended trajectory shape, thus obtaining the trajectory optimization direction.

[0050] Specifically, in one implementation, the coordination report is presented in tabular form, including transmission efficiency stability values, start and end times of each trajectory segment, trajectory type markings, and relevant performance indicators. The hold rate is calculated based on the cumulative time within each trajectory segment where the angle of attack is within the effective propulsion angle range, divided by the total duration of that trajectory segment.

[0051] Specifically, the identification of curved and straight trajectory segments is determined by trajectory curvature. Curvature is equal to the absolute value of x derivative and y derivative minus x derivative and y derivative divided by the cube root of the square of x derivative plus the square of y derivative, where x and y are the coordinates of the trajectory points, x derivative and y derivative are the corresponding first derivatives, and x derivative and y derivative are the second derivatives. If the curvature of a sequence of 5 consecutive sampling points is greater than the threshold of 0.1 per meter, it is classified as a curved trajectory segment; otherwise, it is classified as a straight trajectory segment. The effective propulsion angle range is set from -15 degrees to +15 degrees, within which the blades can generate effective propulsion. The energy loss index is obtained by calculating the ratio of lateral force Fs to total force Ft, i.e., Fs divided by Ft, to obtain the lateral force loss ratio data. When searching, the trajectory segment's time stamp is used for matching. When the retention rate of the curved trajectory is more than 10% higher than that of the straight trajectory, and the energy loss index is less than 20%, the curved trajectory is recommended; otherwise, the straight trajectory is recommended. The trajectory optimization direction includes recommended trajectory shape types and the range of key parameters that need to be adjusted, providing clear guidance for training improvement.

[0052] S107. Adjust the training system acquisition settings according to the trajectory optimization direction, and send the trajectory optimization direction back to the acquisition density adjustment stage to determine the time interval setting for the next data acquisition.

[0053] Based on the recommended trajectory shape type and key parameter range in the trajectory optimization direction, the recommended shape is mapped to the key acquisition area. If an arc trajectory is recommended, the sampling frequency of the arc segment is set to twice the standard frequency; if a straight trajectory is recommended, the sampling frequency of the straight segment is set to twice the standard frequency, resulting in a differentiated acquisition configuration. This differentiated acquisition configuration is transmitted to the acquisition density adjustment module of the training system via control signals. The specific time interval is calculated based on the frequency multiple relationship in the configuration: a 0.005-second interval is used for key areas, and a 0.01-second interval is used for non-key areas, thus determining the time interval setting for the next data acquisition.

[0054] Specifically, in one implementation, the trajectory optimization direction includes a recommended trajectory morphology type identifier and corresponding suggested ranges for key parameters. The morphology type identifier uses binary encoding, with an arc trajectory encoded as 1 and a straight trajectory encoded as 0. Key parameters include suggested angle of attack range, paddling frequency range, and depth of entry range.

[0055] Specifically, the differentiated acquisition configuration is implemented through a lookup table. When the recommended trajectory is an arc, the system automatically sets the sampling frequency of the arc segment to 200 Hz, while keeping the straight segment at 100 Hz; conversely, when a straight trajectory is recommended, the sampling frequency of the straight segment is increased to 200 Hz, while the arc segment remains at 100 Hz. This differentiated setting allows for denser data sampling of the trajectory patterns of interest. The control signal is transmitted to the acquisition controller of the training system via a serial communication protocol. After receiving the configuration information, the controller calculates the corresponding timer parameters based on the frequency value using the formula T = 1 / f, where T is the acquisition interval in seconds and f is the frequency in Hz. For example, 200 Hz corresponds to T = 1 / 200 = 0.005 seconds, and 100 Hz corresponds to T = 1 / 100 = 0.01 seconds. The new acquisition settings can be automatically applied at the start of the next training cycle.

[0056] Example 2: The present invention also discloses an apparatus for implementing the rowing athlete's power output coordination control method in Embodiment 1, comprising: Data acquisition module: acquires three-dimensional coordinate data of the propeller blades moving underwater and hull acceleration data, and generates records containing the changes in propeller blade trajectory radii and hull acceleration. Analysis and Calculation Module: Extracts blade trajectory morphology features from the records, distinguishes between straight and curved trajectories, and determines the accompanying changes of the straight and curved trajectories during hull acceleration; analyzes the deviation between the blade angle of attack deflection and propulsion angle range through these accompanying changes, and calculates the proportion of energy loss caused by the lateral force component; based on the proportion of energy loss and the athlete's exertion time, assesses the time deviation between the exertion time and the peak acceleration, and generates a power output timing coordination score. Identification module: Analyzes the smoothness of force transmission through the coordination score, and identifies the stability of transmission efficiency during the acceleration phase; Output module: Generates a coordination report based on the transmission efficiency stability, evaluates the differences in propulsion angle maintenance among different trajectory morphologies, and determines the direction of trajectory optimization.

[0057] It should be noted that the above data acquisition module specifically includes a camera device. Furthermore, the process of analyzing morphological features, calculating, identifying, and outputting data by each of the above modules is described in Example 1, and will not be elaborated here to avoid redundancy.

[0058] In summary, the method and device for controlling the coordination of rowing athlete power output disclosed in this invention analyzes the changes in paddle trajectory curvature and acceleration, distinguishes between straight and curved trajectories, assesses the impact of angle of attack deflection on propulsion efficiency, identifies energy loss caused by lateral force components, and generates a power output timing coordination score by combining the synchronicity of the athlete's force exertion moment and peak acceleration. This results in a coordination report that guides the control of rowing athlete power output coordination, avoiding energy waste and maintaining the optimal trajectory shape for boat stability. This invention uses a feedback loop to transmit the optimized direction back to the data acquisition settings, achieving adaptive adjustment and significantly improving the accuracy and efficiency of the training system.

[0059] The above embodiments are merely one of the preferred embodiments of the present invention and should not be used to limit the scope of protection of the present invention. Any modifications or refinements made to the main design concept and spirit of the present invention that are not of substantial significance, but solve the same technical problem as the present invention, should be included within the scope of protection of the present invention.

Claims

1. A method for controlling the coordination of power output in rowing athletes, characterized in that, include: Acquire three-dimensional coordinate data of the propeller blades moving underwater and hull acceleration data, and generate a record containing the changes in the radii of the propeller blade trajectory and the hull acceleration. Based on the records, the morphological features of the propeller trajectory are extracted, the straight trajectory and the arc trajectory are distinguished, and the accompanying changes of the straight trajectory and the arc trajectory during the acceleration of the ship are determined. The deviation between the blade angle of attack deflection and the propulsion angle range is analyzed by the accompanying changes, and the proportion of energy loss caused by the lateral force is calculated. Based on the energy loss ratio and the athlete's exertion time, the time deviation between the exertion time and the peak acceleration is evaluated to generate a power output timing coordination score. The smoothness of force transmission is analyzed by the coordination score, and the stability of transmission efficiency during the acceleration phase is identified. Based on the stability of the transmission efficiency, a coordination report is generated to assess the differences in propulsion angle maintenance among different trajectory morphologies and determine the direction of trajectory optimization.

2. The method for controlling the coordination of power output in rowing athletes as described in claim 1, characterized in that, The process of acquiring three-dimensional coordinate data of the propeller blade's underwater motion and hull acceleration data, and generating a record containing the propeller blade trajectory radii and hull acceleration changes, includes: The three-dimensional coordinate sequence of the propeller blades is obtained by an underwater camera device, and the depth of the propeller blades entering the water is calculated. The pressure change curve of the paddle handle is obtained from the force sensor to identify the moment when the athlete exerts force. The instantaneous acceleration of the ship is calculated based on the three-dimensional coordinate sequence. If the rate of change of acceleration exceeds a preset threshold, the data acquisition time interval is adjusted. By resampling the three-dimensional coordinate sequence and pressure change curve at adjusted time intervals, the blade position sequence under different sampling densities can be obtained. The angle of attack deflection is calculated based on the blade position sequence, and the blade trajectory arc curve is obtained by fitting. The entry depth, angle of attack deflection, moment of force application, and hull acceleration values ​​are matched to form a complete record.

3. The method for controlling the coordination of power output in rowing athletes as described in claim 1, characterized in that, The step of extracting propeller trajectory morphology features from the records, distinguishing between straight and curved trajectories, and determining the accompanying changes of the straight and curved trajectories during ship acceleration includes: Read the three-dimensional coordinate points of the blade from the record and calculate the angle between the vectors of adjacent coordinate points; If the angle between the vectors of adjacent coordinate points deviates from the horizontal angle by more than a preset radian threshold, it is marked as an arc-shaped trajectory point; otherwise, it is marked as a straight trajectory point. The trajectory is segmented based on a sequence of continuously marked coordinate points; Extract the numerical sequence of ship acceleration for the corresponding time period from the records, calculate the magnitude of acceleration change during the straight trajectory segment and the arc trajectory segment, and determine the accompanying change characteristics of the straight trajectory and the arc trajectory during ship acceleration.

4. The method for controlling the coordination of power output in rowing athletes as described in claim 1, characterized in that, The process of analyzing the deviation between the blade angle of attack deflection and the propulsion angle range through the accompanying changes, and calculating the proportion of energy loss caused by the lateral force, includes: The blade angle of attack value is read based on the accompanying changes, compared with the preset propulsion angle range, and the difference between the angle of attack and the center value is calculated. If the difference between the angle of attack and the center value exceeds a preset threshold, it is determined to be a deviation state, and the time and angle value of the deviation are recorded. The thrust projection component and lateral component are calculated using the angle of attack value at the deviation time, and the response delay time is obtained based on the component ratio. The average response delay time under different trajectory patterns was statistically analyzed to determine the adaptability index; The instantaneous energy loss rate is calculated based on the proportion of the lateral component, and the average loss rate is statistically calculated according to the deviation angle interval.

5. The method for controlling the coordination of power output in rowing athletes as described in claim 1, characterized in that, The process of assessing the time deviation between the moment of force exertion and the peak acceleration, based on the energy loss ratio and the athlete's force exertion timing, generates a force output timing coordination score, including: Read the loss value sequence from the energy loss ratio and extract the power generation start timestamp; The peak acceleration time point is identified by differential operation on the hull acceleration sequence, and the time difference between the force exertion start time stamp and the peak time point is calculated. The degree of synchronization is determined based on the time difference, the frequency of occurrence of different degrees of synchronization is counted, and the proportion of highly synchronized states is calculated as the synchronization score. The rigidity of the trajectory is assessed based on the variance of the blade angle within the straight trajectory segment, and the correlation between the variance and the proportion of energy loss is calculated to obtain the influence coefficient. The final coordination score is calculated using the synchronicity score and the influence coefficient.

6. The method for controlling the coordination of power output in rowing athletes as described in claim 1, characterized in that, The process of analyzing the smoothness of force transmission through the coordination score and identifying the stability of transmission efficiency during the acceleration phase includes: Based on the coordination score, divide the interval and read the athlete's force curve, propeller propulsion curve, and boat speed curve. Calculate the rate of change of the curve values, and after time alignment, calculate the phase difference value to obtain the power transmission smoothness index. Interference signals are identified and removed through filtering, and the ratio of the variance of the data before and after filtering is calculated as the smoothness. The transmission characteristic value is determined based on the smoothness index and smoothness. The start and end times of the acceleration phase are identified by the feature value sequence, the instantaneous transmission efficiency is calculated, and the stability of the transmission efficiency is determined based on the standard deviation of the efficiency sequence.

7. The method for controlling the coordination of power output in rowing athletes as described in claim 1, characterized in that, The process of generating a coordination report based on the stability of the transmission efficiency, evaluating the differences in propulsion angle maintenance among different trajectory morphologies, and determining the direction of trajectory optimization includes: A coordination report is generated based on the aforementioned transmission efficiency and stability indicators; Extract the effective propulsion angle retention rate of the arc trajectory and the straight trajectory from the coordination report, calculate the difference between the two and obtain the comparison results; The lateral force loss ratio for the corresponding time period is used as an energy loss indicator by comparing the results. If the retention rate of the arc-shaped trajectory is higher than that of the straight-line trajectory and the loss index is lower than the preset threshold, then the arc-shaped trajectory is determined as the recommended trajectory shape; otherwise, the straight-line trajectory is determined as the recommended trajectory shape, and the trajectory optimization direction is obtained.

8. The method for controlling the coordination of power output in rowing athletes as described in claim 1, characterized in that, The method further includes: adjusting the data acquisition settings according to the trajectory optimization direction, and determining the next acquisition time interval.

9. The method for controlling the coordination of power output in rowing athletes as described in claim 8, characterized in that, The step of adjusting the data acquisition settings according to the trajectory optimization direction and determining the next acquisition time interval includes: Key areas are collected based on the recommended trajectory shape mapping in the trajectory optimization direction; If an arc-shaped trajectory is recommended, then set the sampling frequency of the arc segment to twice the standard frequency; If a straight line trajectory is recommended, the sampling frequency of the straight line segment is set to twice the standard frequency to obtain a differentiated acquisition configuration; The differentiated acquisition configuration is transmitted to the acquisition density adjustment module via control signals. The specific time interval is calculated based on the frequency multiple relationship to determine the time interval setting for the next data acquisition.

10. An apparatus for implementing the method for controlling the coordination of power output in rowing athletes as described in any one of claims 1-9, characterized in that, include: Data acquisition module: acquires three-dimensional coordinate data of the propeller blades moving underwater and hull acceleration data, and generates records containing the changes in propeller blade trajectory radii and hull acceleration. Analysis and Calculation Module: Extracts blade trajectory morphology features from the records, distinguishes between straight and curved trajectories, and determines the accompanying changes of the straight and curved trajectories during hull acceleration; analyzes the deviation between the blade angle of attack deflection and propulsion angle range through these accompanying changes, and calculates the proportion of energy loss caused by the lateral force component; based on the proportion of energy loss and the athlete's exertion time, assesses the time deviation between the exertion time and the peak acceleration, and generates a power output timing coordination score. Identification module: Analyzes the smoothness of force transmission through the coordination score, and identifies the stability of transmission efficiency during the acceleration phase; Output module: Generates a coordination report based on the transmission efficiency stability, evaluates the differences in propulsion angle maintenance among different trajectory morphologies, and determines the direction of trajectory optimization.

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