CN118267687A - Force measuring system and method for measuring and evaluating comprehensive technical ability of rock climbing athlete - Google Patents

Abstract

The present invention provides a force measurement system and method for measuring and evaluating the comprehensive technical ability of rock climbers, including: a portable detachable steel frame structure, a force sensor and a computer; the portable detachable steel frame structure is composed of a plurality of steel pipes to form a climbing frame for rock climbers to climb, and the force sensor can be simply and portablely installed and adjusted; the force sensor is used to measure the triaxial force value applied by the rock climber on the rock point; the computer is used to explore the mechanical relationship between the human-fulcrum according to the triaxial force value measured by the force sensor, analyze the factors affecting the successful completion of technical movements, quantify the strength index of the hands, feet and dynamic movement technology of rock climbers at different rock points, establish a method and index for monitoring and evaluating the hand, foot and dynamic movement technology level of rock climbers, and provide a systematic and scientific quantitative index for rock climbing training. The present invention can measure and evaluate the comprehensive technical ability of rock climbers.

Description

A force measurement system and method for measuring and evaluating the comprehensive technical ability of rock climbers

Technical Field

The present invention relates to the technical field of sports equipment, and in particular to a force measuring system and method for measuring and evaluating the comprehensive technical ability of rock climbers.

Background technique

Rock climbing requires athletes to climb with their hands free, and their hands and feet must adapt to the characteristics of the rock wall and rock points to choose appropriate technical movements and make corresponding adjustments. Rock climbing is a continuous action consisting of three links: grabbing the rock points, completing the hand and foot techniques, and pushing and pulling the body to move. Among them, the effective grabbing and stepping on the rock points by rock climbers are the most basic links, and are the prerequisite for rock climbing to further support suspension, movement, and climbing techniques.

Rock climbing is not only time-consuming, but also the rock features of the rock walls and routes are complex and diverse during the climbing process, which places high demands on the athlete's technical level and comprehensive qualities such as strength. Rock climbing requires athletes to flexibly choose appropriate technical movements based on route characteristics, rock wall angles and shapes, and rock geometry. The athlete's hand grasping of the rock needs to choose appropriate technical movements based on the rock's changing shape, size, angle and other characteristics. The selection of hand and foot techniques and the completion effect are important factors affecting climbing performance.

At present, there is no literature that proposes a force measurement system for quantitatively measuring and evaluating the comprehensive technical ability of rock climbers' hands and feet, so as to quantitatively obtain the mechanical relationship between the person and the fulcrum of the rock climbing action. Therefore, there is a need for a method to measure and evaluate the technical strength indicators of the hands and feet of rock climbers at different rock points, to establish a method and indicator for monitoring and evaluating the technical level of rock climbing hands, and to provide systematic and scientific quantitative indicators for rock climbing training to fill this technical research gap.

Summary of the invention

The present invention provides a force measurement system and method for measuring and evaluating the comprehensive technical ability of rock climbers, which is used to measure and evaluate the comprehensive technical ability of rock climbers. The technical solution is as follows:

The present invention provides a force measuring system for measuring and evaluating the comprehensive technical ability of rock climbers, comprising:

Portable and removable steel frame structure, load cell and computer;

The portable and detachable steel frame structure is constructed by combining a number of steel pipes to form a climbing frame for rock climbers to climb, and the force sensor can be installed and adjusted in a simple and portable manner;

The force sensor is used to measure the triaxial force values applied by the rock climber on the rock point;

The computer is used to explore the mechanical relationship between the person and the fulcrum based on the three-axis force values measured by the force sensor, analyze the factors that affect the successful completion of technical movements, quantify the strength indicators of the hands, feet and dynamic movement techniques of rock climbers at different rock points, establish methods and indicators for monitoring and evaluating the hand, foot and dynamic movement technical levels of rock climbers, and provide systematic and scientific quantitative indicators for rock climbing training.

On the other hand, a method for measuring and evaluating the comprehensive technical ability of a rock climber is provided, wherein the above-mentioned force measurement system is used for measurement and evaluation, and the method comprises:

S1. Recruit a number of rock climbers and record their personal information;

S2. Determine the test action and plan, assemble the rock point-sensor complex according to the test action plan, install the force sensor composed of the rock point-sensor complex, arrange the test environment, debug and check the force measurement system;

S3, rock climbers complete pre-test warm-up preparations;

S4. According to the specific test requirements, the rock climber completes the specified test action techniques, and the triaxial force values applied by the rock climber on the rock point are measured. The test action techniques include action techniques in the three categories of hand techniques, foot techniques and dynamic movement;

S5. Based on the three-axis force values, explore the mechanical relationship between the person and the fulcrum, analyze the factors that affect the successful completion of technical movements, quantify the strength indicators of the hands, feet and dynamic movement techniques of rock climbers at different rock points, establish methods and indicators for monitoring and evaluating the levels of hands, feet and dynamic movement techniques of rock climbers, and provide systematic and scientific quantitative indicators for rock climbing training.

Compared with the prior art, the above technical solution has at least the following beneficial effects:

1) The force measuring system for measuring and evaluating the comprehensive technical ability of rock climbers of the present invention can be installed at any rock point position, and the number, type, angle, etc. of rock points can be selected and installed according to the test and evaluation objectives; the rock points on the simulated wall position can also be flexibly changed to form various combinations of different types of rock points and different distances between rock points. The force test is relatively quick and the feedback is fast. It can be used to monitor the scientific training of athletes, overcome the problems of slow feedback and no quantitative data in the technical analysis of video shooting movements, and make up for the deficiency of over-reliance on the experience of coaches.

2) The force measurement system and method for measuring and evaluating the comprehensive technical ability of rock climbers in the present invention can construct a data set of interaction forces between hands, feet and rock points in rock climbing, and can further compare the hand techniques, foot techniques and dynamic movement technical abilities of different athletes, or compare the left and right side techniques of the same athlete, or compare the hand techniques, foot techniques and dynamic movement technical abilities of the same athlete before and after stage training.

3) The force measurement system and method for measuring and evaluating the comprehensive technical ability of rock climbers of the present invention can diagnose and optimize the corresponding action techniques of athletes during rock climbing based on the mechanical elements related to the rock climbing action techniques, form an evaluation report, quickly perform sports technical analysis, and put forward suggestions for improvement.

4) The force measuring system for measuring and evaluating the comprehensive technical ability of rock climbers of the present invention has the characteristics of being portable, easy to install, disassemble and transport, and having stable performance.

5) The force measurement system and method for measuring and evaluating the comprehensive technical ability of rock climbers of the present invention can be applied to the selection and daily training of high-level athletes, the construction of a digital training system, and intelligent auxiliary training.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

FIG1 is a schematic diagram of a force measurement system for measuring and evaluating the comprehensive technical ability of a rock climber provided by an embodiment of the present invention;

FIG2 is a physical diagram of a force measurement system for measuring and evaluating the comprehensive technical ability of a rock climber provided by an embodiment of the present invention;

FIG3 is a physical diagram of a force measuring system and a protection device for measuring and evaluating the comprehensive technical ability of a rock climber provided by an embodiment of the present invention;

FIG4 is a flow chart of a method for measuring and evaluating the comprehensive technical ability of a rock climber provided by an embodiment of the present invention;

FIG5 is a side view of a rock climber performing a grip test using the left hand of a rock climber using gripping, half gripping, and full gripping, respectively, according to an embodiment of the present invention;

FIG6 is a dynamic force curve diagram of a rock climber using gripping, half gripping, and full gripping to grip a rock point, respectively, according to an embodiment of the present invention;

FIG7 is a schematic diagram of moment analysis of a rock climber under different body posture conditions provided by an embodiment of the present invention;

FIG8 is a schematic diagram of a body center of mass trajectory and target rock points of a rock climber during dynamic movement provided by an embodiment of the present invention;

FIG. 9 is a diagram showing a gripping and pinching technique test performed by a rock climber with surface electromyography electrodes attached thereto according to an embodiment of the present invention.

Figure numerals: 111 is a horizontal bar of a portable detachable steel frame structure, 112 is a force sensor fixing bar, 113 is a vertical bar of a portable detachable steel frame structure, 114 is a fastener of a connecting bar, 115 is a side bar, 116 is a bottom bar sleeve, 117 is a bottom bar; 121 is a force sensor (rock point-sensor complex); 131 is a sensor connecting steel plate; 141 is a wooden board or a hard plastic board.

Detailed ways

In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

The embodiment of the present invention provides a force measurement system for measuring and evaluating the comprehensive technical ability of rock climbers, comprising: a portable and detachable steel frame structure, a force measurement sensor and a computer;

The portable and detachable steel frame structure is constructed by combining a number of steel pipes to form a climbing frame for rock climbers to climb, and the force sensor can be installed and adjusted in a simple and portable manner;

The force sensor is used to measure the triaxial force values applied by the rock climber on the rock point;

The computer is used to explore the mechanical relationship between the person and the fulcrum based on the three-axis force values measured by the force sensor, analyze the factors that affect the successful completion of technical movements, quantify the strength indicators of the hands, feet and dynamic movement techniques of rock climbers at different rock points, establish methods and indicators for monitoring and evaluating the hand, foot and dynamic movement technical levels of rock climbers, and provide systematic and scientific quantitative indicators for rock climbing training.

To simulate a real rock climbing scene, a climbing frame consisting of a portable detachable steel frame structure with a height of 2.4 meters and a width of 2.2 meters is designed and built in an embodiment of the present invention, as shown in FIGS. 1 and 2 .

Optionally, the portable detachable steel frame structure adopts universal scaffolding steel pipes and fasteners, which are convenient for disassembly and installation, and for adjusting the climbing point position as needed. The double steel pipes 112-double steel plates 131 are connected to the force sensor 121, and multiple force sensors can be installed and tested at the same time. The double steel pipes 112-double steel plates 131 and the force sensors 121 in the upper left, lower left, upper right, and lower right quarter assembly areas can all adjust their positions to simulate the hand grasping and foot pedaling positions of rock climbers in various climbing movements and postures.

Optionally, the force sensor 121 is a rock point-sensor complex, consisting of a rock point, a sensor and a force guide plate, and is connected to a steel plate to be fixed to the climbing frame. Rock points of any shape can be flexibly selected, and the rock point positions can be arranged arbitrarily as required. The sensor is a three-axis force sensor, which measures the three-axis forces of the hands and feet exerted on the rock points under different rock point characteristic conditions, using different hand and foot techniques and dynamic movements, so that rock climbers can complete the measurement and evaluation of the action technical characteristics of any combination of rock points.

Optionally, as shown in FIG3 , the force measuring system further includes a protective device 141, which is composed of a protective plate installed on the periphery after the position of the force measuring sensor is fixed, and a protective pad attached to the protective plate, which is used to prevent slippage and empty climbing during the climbing simulation test from causing unnecessary injuries to the rock climber. The force applied by the rock climber to the rock point passes through a three-axis force sensor and its amplifier and receiver, and is ultimately displayed as a corresponding three-axis force value on the rock point-three-dimensional force test system acquisition software of the computer. As shown in FIG4 , an embodiment of the present invention also provides a method for measuring and evaluating the comprehensive technical ability of rock climbers, and the above-mentioned force measuring system is used for measurement and evaluation. The method includes: S1, recruiting a number of (for example, 200) rock climbers, and recording the personal information of the rock climbers (including name, gender, age, years of training, training level, weekly training frequency and time, etc.); S2, determining the test action and plan, assembling the rock point-sensor complex according to the test action plan, installing the force sensor composed of the rock point-sensor complex, arranging the test environment, and debugging and inspecting the force measuring system;

S3. The rock climber completes the pre-test warm-up (e.g., 5-minute jogging warm-up).

S4. According to the specific test requirements, the rock climber completes the specified test action techniques, and the triaxial force values applied by the rock climber on the rock point are measured. The test action techniques include action techniques in the three categories of hand techniques, foot techniques and dynamic movement;

S5. Based on the three-axis force values, explore the mechanical relationship between the person and the fulcrum, analyze the factors that affect the successful completion of technical movements, quantify the strength indicators of the hands, feet and dynamic movement techniques of rock climbers at different rock points, establish methods and indicators for monitoring and evaluating the levels of hands, feet and dynamic movement techniques of rock climbers, and provide systematic and scientific quantitative indicators for rock climbing training.

Optionally, the S4 specifically includes:

Test the interaction force indicators between rock climbers' hands and rock holds and feet and rock holds, including but not limited to: peak force, three-dimensional peak force in vertical, front-back and left-right directions, relative peak force of peak force/body weight, relative three-dimensional peak force in vertical, front-back and left-right directions, average resultant force during rock contact time, average triaxial force during rock contact time (vertical, front-back and left-right directions), endurance duration (80% peak force duration), resultant force growth rate, vertical force growth rate, front-back force growth rate, left-right force growth rate, resultant impulse, vertical impulse, front-back impulse, left-right impulse, rock reaction force angle and lower limb force contribution rate.

The embodiment of the present invention summarizes the action technical indicators of 200 athletes to form a action technical level data set formed by rock climbers, performs statistical analysis on the action technical data set of rock climbers, analyzes the statistical distribution characteristics of various indicators, and calculates their percentile values. The rock climbing action technical data set is an open data set and is continuously updated during the test process. After completing the test of each athlete, the data set is updated to form a more comprehensive and rich data set. The embodiment of the present invention can compare the personalized athlete test data with the existing rock climber action technical data set, analyze its percentile position, and generate an evaluation report at the same time. According to the evaluation report, outstanding athletes are recommended to enter higher-level sports teams for training to complete the talent selection work.

When climbing, the hands and feet are the only points of contact between the climber's body and the rock. Compared with the feet, which are covered by shoes, the hands can respond flexibly and changeably to grab various strange-shaped rock points. Grasping the rock point is an important factor in determining the success of rock climbing.

Optionally, the action techniques of the technique specifically include:

Correctly select the technique that suits the shape of the rock point, flexibly use the friction between the fingers and the palm, and save energy as much as possible. There are many types of techniques, including but not limited to: full grab, half grab, hook, grab, pinch, buckle, wrap, forward grab, side pull, reverse support and reverse grab. Different techniques have different technical essentials and specific classifications. Rock climbers must rely on the characteristics of the rock wall and the rock point to choose the correct grip, and choose the grip that can still support and balance the body on a difficult route, as well as the technique that saves as much energy as possible. Perform technical tests on rock climbers using various techniques. For example, as shown in Figure 5, taking the technical level tests of the three techniques of grab, half grab and full grab as an example, assemble the rock point-sensor complex according to the test action plan, install the grab, half grab and full grab rock points respectively, debug and check that the force measurement system hardware and software are running normally, complete the preparations before the test, and use the force measurement system to test the rock point-sensor complex. The athletes are systematically tested for the three techniques of subjective maximum force, namely, grabbing, half-gripping and full-gripping. The data of dynamic changes of the three-axis force of various techniques over time are obtained from the force sensors respectively. The key technical indicators of various techniques are extracted from the dynamic change data of the three-axis force, including but not limited to: absolute grip peak force (the total traction peak when the subject performs subjective maximum force grip on the rock point), relative grip peak force (the total traction peak relative to the body weight when the subject performs subjective maximum force grip on the rock point), vertical peak force, front-back peak force, lateral peak force (the peak traction in each direction relative to the body weight when the subject performs subjective maximum force grip on the rock point), peak force duration (duration of 80% of the maximum force), force growth rate (the maximum value of the slope of the force value curve), impulse (integral of force over time);

In one test, a rock climber's peak forces in the Z-axis direction using the full-grab, grab and half-grab techniques were 423N, 338N and 282N respectively, and the forces in the X and Y directions were relatively small, as shown in Figure 6. Based on these values, we can see the corresponding percentile levels of this rock climber in the rock climbing action technology dataset, which are 67%, 64% and 72% for the full-grab, grab and half-grab techniques. This quantitatively measures the technical levels of the three techniques of this rock climber.

Optionally, the footwork action techniques specifically include:

The key points of rock climbing footwork are the way the feet step on the rock points and the method of applying force. Rock climbing requires the flexible use of the power of the feet. The feet are stronger than the hands and are relatively less prone to fatigue. Reasonable movement techniques require the use of the feet as the propulsion force for climbing up to reduce the weight of the hands. The hands are responsible for balancing the body and guiding the direction of advancement, and push up with the power of the feet. The elements of footwork include but are not limited to: pushing, rubbing and rubbing. Pushing is to clamp the climbing foot on a narrow rock edge, which is suitable for small rock points and rock slabs. Rubbing is to press the foot hard on the rock wall or rock point to obtain support. The rubbing action technique takes into account the effects of pushing and rubbing at the same time. There are many types of footwork, including but not limited to: straight stepping, inner stepping, outer stepping, side stepping, buckling and hooking;

Among them, when the rock climber uses the outside stepping technique, there are two rock points above and below for the rock climber to push and grasp upward, and the maximum combined force of the limbs The larger the value, the greater the dynamic acceleration a that can be provided to the rock climber. The calculation formula is:

(1)

In the formula, F is the force vector, m is the body mass of the rock climber, g is the weight acceleration vector, and a is the body center of mass acceleration vector;

When climbing, the selection and implementation of hand and foot techniques are very important. There are many different techniques for the same rock position, but even if one technique is used, some climbers can pass it smoothly while others cannot. The efficiency of hand and foot techniques varies depending on the center of gravity position, that is, the body posture and center of gravity position of the climber. The action techniques of the climber need to be analyzed:

As shown in Figure 7, in the vertical direction of gravity, when the resistance point is far away from the fulcrum, the force required at the force application point is greater, and when the resistance point is close to the fulcrum, the force required at the force application point is smaller. The smaller the horizontal distance from the center of gravity to the left foot, the better the action technique. Since the resistance torque and the power torque are equal in magnitude and opposite in direction, when the resistance arm is smaller, the resistance torque is smaller when the resistance (body weight) remains unchanged, and the power required is smaller when the force application point remains unchanged. The calculation formula is as follows:

(2)

In the formula, G is the resistance, that is, the weight of the rock climber; _L1 is the force arm of the resistance, that is, the distance from the fulcrum to the resistance point; F is the power, and _L2 is the force arm of the power, that is, the distance from the fulcrum to the force application point;

The rock climbers were tested on the outside stepping technique three times, and the dynamic data of the three-axis force changing with time during the three movements were obtained from the force sensor, including the dynamic data of the three-axis force changing with time on the four force measuring rock points of the left and right hands and the left and right feet;

The dynamic data of the triaxial force changing with time are further processed to obtain the key mechanical indicators of the left and right hands and left and right feet in the action technique, including but not limited to: absolute hand grasping and foot extension peak force, relative hand grasping and foot extension peak force (absolute peak force divided by the weight of the rock climber), vertical peak force, anterior-posterior peak force, lateral peak force, force growth rate (maximum value of the slope of the force curve), impulse (integral of force over time), upper limb peak force ratio (ratio of the sum of the peak forces of the left and right upper limbs to the peak forces of the four limbs), upper limb average force ratio (ratio of the sum of the average forces of the left and right upper limbs to the sum of the average forces of the four limbs within a certain period of time);

Compare the key mechanical indicators of the three outside stepping techniques, use video recording to assist in analyzing the differences in the effects of the three movements, analyze the completion effects of the outside stepping techniques, and evaluate the technical level of the movements:

Analyze which action technique is more labor-saving in the same rock point arrangement, how the triaxial force of the limbs changes, and form a rock climbing action characteristic data set; analyze whether the athlete's action technique is reasonable, and put forward suggestions for improvement to form an evaluation report. For the same hand and foot techniques, as shown in (a) of Figure (7), the maximum triaxial force of the right hand in the first test is 300N, and as shown in (b) of Figure (7), the maximum triaxial force of the second test is 120N. In the first action, the horizontal distance between the body center of gravity and the fulcrum is far, so it is recommended that rock climbers pay attention to shifting the body center of gravity to the left in this rock point environment.

In real rock climbing environments, some rock holds are far apart and require jumping to grab the far rock holds. Since the distance between the handholds on the rock wall is too large, the climber jumps through the path between the handholds and then grabs the next handhold, which is a dynamic movement technique. During the action, the climber completely leaves the rock wall. If the climber fails to accurately grab the next handhold, they will fall off the rock wall.

Optionally, the dynamic movement technique specifically includes:

The effective use of force in dynamic movement techniques is crucial. By increasing the time of force action to reduce the size of force, or using force to generate greater explosive force to effectively exert movement techniques and achieve the moving goal, the key to dynamic movement is to apply force to the rock points at the beginning of the upper and lower limbs to generate acceleration of the human limbs, so that the human body leaves the rock wall and flies to the next group of rock points to achieve the effect of dynamic movement. In dynamic movement, the feet generate strong thrust, and the hands play the role of pulling and controlling the direction. When the body moves to a certain height, the opposite side of the grabbing hand needs to continue to push the hand point to the end. In this process, the longer the opposite side of the protective hand acts, the more the force time can be increased to increase the movement speed, which helps to increase the jumping distance. There are many types of dynamic movement techniques, including but not limited to: squat jump, one-hand squat jump, coordinated jump, gravity assist, zero and finger jump. All dynamic movement techniques are divided into three stages: take-off stage, air stage and wall fall stage. Whether the dynamic movement of rock climbers can achieve successful movement to the target rock point depends on the movement speed formed in the take-off stage and the spatial position (distance) of the next rock point.

Regardless of the dynamic movement technique used by rock climbers, the power of dynamic movement is jointly generated by the pedaling force and the hand pulling force, and the movement of the body's center of mass always follows Newton's second law, that is, the dynamic equation of formula (1);

According to the law of momentum, the momentum generated by the climber during the take-off phase is equal to the impulse received during this phase, and the impulse received by the climber during the take-off phase is the vector sum of the impulses generated by the climber using the pedals and the hands to pull the rock:

(3)

In the formula, It is the sum of the impulse vectors generated by the forces applied to the rock by both feet and hands. is the instantaneous body mass center velocity vector of the rock climber at the end of the take-off phase;

Assuming that the climber is stationary when taking off, and the velocity of his center of mass is zero, the impulse vector is calculated according to the following formula:

(4)

In the formula, are the acting time of the force of the left foot, right foot, left hand and right hand during the take-off process, is the time-varying function of the force vector;

As shown in Fig. 8, a three-dimensional coordinate system Oxyz is established, where the origin O of the coordinate system is located on the stationary ground, and x, y, and z are the sagittal axis (front and back), coronal axis (left and right), and vertical axis (up and down) of the body of the rock climber, respectively;

At this time, formula (4) is orthogonally decomposed into three equations in three-dimensional space:

(5)

Combining formula (5) with formula (3), we can obtain the three components of the velocity of the center of mass of the rock climber after the take-off phase is completed:

(6)

In the formula, , , They are the center of mass speed of the rock climber at the instant of take-off and end of jump;

The force vector data of the feet and hands in formula (6) are measured and obtained by the force sensor, and the center of mass velocity of the rock climber after taking off is calculated by digital integration through the pedaling force of the left and right feet and the pulling force of the left and right hands;

After the rock climber completes the take-off action, he enters the air flight action. At this time, the rock climber is only affected by the gravity acting on the center of mass. The center of mass follows a parabolic motion trajectory. The coordinates of the center of mass during the body's air movement are Calculated according to the formula:

(7)

In the formula, , , They are the initial position coordinates of the center of mass of the rock climber’s body before taking off;

If the climber grabs the next rock hold without considering it, the time from the air movement to the landing is calculated by the third sub-formula of formula (7), which is set to T;

Furthermore, the rock climber adopts dynamic movement, the center of mass jumps from point A into the air, and uses the right hand to grab the target rock point C during the flight. The three-dimensional coordinates of point C are set as , the calculation formula for calculating the distance between the body center of mass and the target rock point C is:

(8)

During the parabolic motion of the center of mass in the air, the right hand needs to grasp the target rock point. During the motion, the distance between the center of mass of the body and the center of the right palm should be less than or equal to the length of the trunk plus the length of the right upper limb. Let the length of the trunk plus the length of the right upper limb be L ₀ ;

To derive the minimum value of the distance L(t) between the body mass center COM and the target rock point C, square both sides of formula (8) to obtain:

(9)

Deriving both sides of formula (9) and rearranging it, we get formula (10):

(10)

when When is the minimum value, there must be a function The derivative of is 0, as shown in formula (11):

8

(11)

Substituting equation (7) into the derivative term of equation (11) above, we obtain equation (12):

(12)

By numerically solving formula (12), we find When t _min is the minimum value, substitute t _min into formula (8) to calculate The minimum value _Lmin ;

The above derivation calculation The instantaneous t _min when is the minimum value is the result of theoretical analysis. However, in actual numerical calculation, the embodiment of the present invention can calculate the Find the minimum value of each discrete time point in the 0~T stage (for example, the interval between two adjacent time points is 0.01s).

Finish The minimum value _Lmin in the 0~T stage is used to determine the change in the distance between the rock climber's center of mass and the target rock point, and to determine whether the rock climber has a chance to grab the target rock point. The result is determined according to the following discriminant:

(13)

The force measurement system is used to assess whether a rock climber can use dynamic movement techniques to jump from point A with a center of mass at point B to grab a target rock at point C, including:

Measure and estimate the maximum distance L ₀ between the center of mass of the rock climber and the center of the right palm, and measure and calculate the initial coordinates of the center of mass before taking off in the mobile technique. , and the coordinates of the target rock point C ;

The dynamic data of the three-axis force changing with time during the action are collected from the force sensor, including the dynamic data of the three-axis force changing with time on the four force measuring rock points of the left and right feet and the left and right hands. The center of mass velocity of the rock climber after taking off is calculated using formula (6), where the velocity in the x direction is calculated by the following method:

(14)

In the formula, To calculate the force measured by the force measuring system during the take-off process The numerical integration of the pedaling force in the direction over time is calculated as The impulse in the direction, is the time interval (for example, when the sampling frequency of the force sensor is 100 Hz, ), the meanings of other numerical integral terms in formula (14) are similar, m is the body mass of the rock climber;

According to formula (14), , , Then, the dynamic changes of the center of mass trajectory coordinates of the rock climber's body during aerial motion are calculated using formula (7): ;

According to formula (8), the dynamic change of the distance L(t) from the target rock point C during the rock climber's flight in the air is calculated. On this basis, the size of L(t) and _L0 is compared according to formula (13) to determine whether the rock climber can grab the target rock point C;

In addition, when the human body jumps to the target rock point and leaves the rock point, there is no external force except gravity. At this time, the movement trajectory of the human body's center of gravity is a parabola. During the parabolic movement, one or both hands need to grasp the target rock point. During the movement, the distance between the body's center of gravity and the center of the right palm should be less than or equal to the trunk length plus the right upper limb length _L0 . Then, if the minimum distance _Lmin between the center of gravity parabola and the target rock point is greater than _L0 , the rock point cannot be grasped. The best action is to adjust the body posture and grasp the target rock point before and after approaching the minimum distance _Lmin between the center of gravity parabola and the target rock point.

When rock climbers complete all the three major types of movements, namely hand techniques, foot techniques and dynamic movements, they use the coordinated cooperation of multiple muscles to produce different forms of movements. How to analyze and evaluate the relevant muscle working characteristics of different muscles in the process of completing the movements (including activation levels and their coordinated cooperation relationships) and the effects of such working characteristics are important methods for evaluating high-level rock climbers.

Optionally, the method further comprises:

Evaluate the muscle activity and mechanical indexes of rock climbers during the three major movements of hand techniques, foot techniques and dynamic movement. For rock climbers to grasp and pinch one grasping point and two pinching points of different widths, analyze and evaluate the working characteristics and mechanical indexes of the relevant muscles, including:

As shown in Figure 9, electromyographic electrodes are attached to the skin surface of the superficial muscles of the upper limbs and trunk related to the grasping and pinching techniques (such as the superficial flexor muscles of the fingers, the extensor muscles of the fingers, the ulnar flexor muscles of the wrist, the radial flexor muscles of the wrist, the pectoralis major, the biceps brachii, the lower trapezius muscle, and the latissimus dorsi muscle);

The athletes were tested for their subjective maximum strength of grasping and pinching three times using force sensors. During the test, the dynamic change data of triaxial force over time was obtained from the force sensors. The surface electromyography (sEMG) signals of the superficial muscles of the upper limbs and trunk were synchronously collected through the surface electromyography system.

The differences in technical indicators under the three rock holding conditions were analyzed, compared and evaluated. The indicator data were defined as follows: Absolute pinch grip peak force: the total traction peak when the climbers perform subjective maximum force pinch grip on the pinch point; Relative pinch grip peak force: the total traction peak relative to the body weight when the climbers perform subjective maximum force pinch grip on the pinch point; Vertical peak force, anterior-posterior peak force, lateral peak force: the traction peaks in each direction relative to the body weight when the climbers perform subjective maximum force pinch grip on the pinch point; Peak force ratio: refers to the ratio of relative pinch grip peak force to relative grip peak force, where relative grip peak force is the total traction peak relative to the body weight when the climbers perform subjective maximum force grip on the grip point; Peak force difference refers to the difference between relative grip peak force and relative pinch grip peak force;

The average surface electromyography amplitude RMS, integrated electromyography iEMG and contribution rate of different muscles of the superficial muscles of the upper limbs were calculated, the activation degree of different muscles and the coordination relationship between different muscles, as well as the correlation between muscle activation characteristics and pinch grip strength were analyzed, and the level of individual athletes' technical movements was evaluated.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. A force measuring system for measuring and evaluating the comprehensive technical ability of rock climbers, characterized by comprising: a portable and detachable steel frame structure, a force sensor and a computer; The portable and detachable steel frame structure is constructed by combining a number of steel pipes to form a climbing frame for rock climbers to climb, and the force sensor can be installed and adjusted in a simple and portable manner; The force sensor is used to measure the triaxial force values applied by the rock climber on the rock point; The computer is used to explore the mechanical relationship between the person and the fulcrum based on the three-axis force values measured by the force sensor, analyze the factors that affect the successful completion of technical movements, quantify the strength indicators of the hands, feet and dynamic movement techniques of rock climbers at different rock points, establish methods and indicators for monitoring and evaluating the hand, foot and dynamic movement technical levels of rock climbers, and provide systematic and scientific quantitative indicators for rock climbing training. 2. The force measuring system according to claim 1 is characterized in that the portable and detachable steel frame structure adopts universal scaffolding steel pipes and fasteners, which are convenient for disassembly and installation, and convenient for adjusting the climbing point position as needed. Double steel pipes and double steel plates are used to connect with the force sensor, and multiple force sensors can be installed and tested at the same time. The double steel pipes and double steel plates and the force sensors in the upper left, lower left, upper right, and lower right quarter assembly areas can adjust the position to simulate the hand grasping and foot pedaling positions of rock climbers in various climbing movements and postures. 3. The force measuring system according to claim 1 is characterized in that the force sensor is a rock point-sensor complex, which is composed of a rock point, a sensor and a force transmission guide plate, and is connected to a steel plate to be fixed to the climbing frame. Rock points of any shape can be flexibly selected, and the rock point positions can be arranged arbitrarily as required. The sensor is a three-axis force sensor, which measures the three-axis forces of the hands and feet exerted on the rock points under different rock point characteristic conditions, using different hand and foot techniques and dynamic movements, so that rock climbers can complete the measurement and evaluation of the action technical characteristics of any combination of rock points. 4. The force measuring system according to claim 1 is characterized in that the force measuring system also includes a protection device, which is composed of a protection plate installed on the periphery after the position of the force measuring sensor is fixed, and a protection pad attached to the protection plate, which is used to prevent slipping and climbing in vain during the climbing simulation test to cause unnecessary injuries to the rock climbers. 5. A method for measuring and evaluating the comprehensive technical ability of a rock climber, using the force measurement system according to any one of claims 1 to 4 for measurement and evaluation, the method comprising: S1. Recruit a number of rock climbers and record their personal information; S2. Determine the test action and plan, assemble the rock point-sensor complex according to the test action plan, install the force sensor composed of the rock point-sensor complex, arrange the test environment, debug and check the force measurement system; S3, rock climbers complete pre-test warm-up preparations; S4. According to the specific test requirements, the rock climber completes the specified test action techniques, and the triaxial force values applied by the rock climber on the rock point are measured. The test action techniques include action techniques in the three categories of hand techniques, foot techniques and dynamic movement; S5. Based on the three-axis force values, explore the mechanical relationship between the person and the fulcrum, analyze the factors that affect the successful completion of technical movements, quantify the strength indicators of the hands, feet and dynamic movement techniques of rock climbers at different rock points, establish methods and indicators for monitoring and evaluating the levels of hands, feet and dynamic movement techniques of rock climbers, and provide systematic and scientific quantitative indicators for rock climbing training. 6. The method according to claim 5, characterized in that said S4 specifically comprises: Test the interaction force indicators between hand-rock and foot-rock of rock climbers, including but not limited to: peak force, three-dimensional peak force in vertical, front-back and left-right directions, relative peak force of peak force/body weight, relative three-dimensional peak force in vertical, front-back and left-right directions, average resultant force during rock contact time, average triaxial force during rock contact time, endurance duration, resultant force growth rate, vertical force growth rate, front-back force growth rate, left-right force growth rate, resultant impulse, vertical impulse, front-back impulse, left-right impulse, rock reaction force angle and lower limb force contribution rate. 7. The method according to claim 5, characterized in that the action techniques of the technique specifically include: Correctly select the technique that suits the shape of the rock point, flexibly use the friction between the fingers and the palm, and save effort as much as possible. There are many types of techniques, including but not limited to: full grab, half grab, hook, grab, pinch, buckle, wrap, forward grab, side pull, reverse support and reverse grab. Different techniques have different technical essentials and specific classifications. Rock climbers must rely on the characteristics of the rock wall and rock points to choose the correct grip, and choose a grip that can still support and balance the body on a difficult route, as well as a technique that saves as much effort as possible. Perform technical tests on various techniques on rock climbers, obtain data on the dynamic changes of the three-axis force of various techniques over time from the force sensor, and extract key technical indicators of various techniques from the dynamic change data of the three-axis force, including but not limited to: absolute grip peak force, relative grip peak force, vertical peak force, front-back peak force, lateral peak force, peak force duration, force growth rate, and impulse; In one test, a rock climber's peak forces in the Z-axis direction using the full-grab, grab and half-grab techniques were 423N, 338N and 282N respectively, and the forces in the X and Y directions were relatively small. Based on these values, the corresponding percentile levels of this rock climber in the rock climbing action technical data set were 67%, 64% and 72% for the full-grab, grab and half-grab techniques. This quantitatively measured the technical levels of the rock climber's three techniques. 8. The method according to claim 5, characterized in that the footwork action techniques specifically include: The key points of rock climbing footwork are the way the feet step on the rock points and the method of applying force. Rock climbing requires the flexible use of the power of the feet. The feet are stronger than the hands and are relatively less prone to fatigue. Reasonable movement techniques require the use of the feet as the propulsion force for climbing up to reduce the weight of the hands. The hands are responsible for balancing the body and guiding the direction of advancement, and push up with the power of the feet. The elements of footwork include but are not limited to: pushing, rubbing and rubbing. Pushing is to clamp the climbing foot on a narrow rock edge, which is suitable for small rock points and rock slabs. Rubbing is to press the foot hard on the rock wall or rock point to obtain support. The rubbing action technique takes into account the effects of pushing and rubbing at the same time. There are many types of footwork, including but not limited to: straight stepping, inner stepping, outer stepping, side stepping, buckling and hooking; Among them, when the rock climber uses the outside stepping technique, there are two rock points above and below for the rock climber to push and grasp upward, and the maximum combined force of the limbs The larger the value, the greater the dynamic acceleration a that can be provided to the rock climber. The calculation formula is: (1) In the formula, F is the force vector, m is the body mass of the rock climber, g is the weight acceleration vector, and a is the body center of mass acceleration vector; Analysis of the movement techniques of rock climbers: When the resistance point is far away from the fulcrum, the force required at the force application point is greater. When the resistance point is close to the fulcrum, the force required at the force application point is smaller. The smaller the horizontal distance from the center of gravity to the left foot, the better the action technique. Since the resistance torque and the power torque are equal in magnitude and opposite in direction, when the resistance arm is smaller, the resistance torque is smaller when the resistance remains unchanged, and the power required is smaller when the force application point remains unchanged. The calculation formula is as follows: (2) In the formula, G is the resistance, that is, the weight of the rock climber; _L1 is the force arm of the resistance, that is, the distance from the fulcrum to the resistance point; F is the power, and _L2 is the force arm of the power, that is, the distance from the fulcrum to the force application point; The rock climbers were tested on the outside stepping technique three times, and the dynamic data of the three-axis force changing with time during the three movements were obtained from the force sensor, including the dynamic data of the three-axis force changing with time on the four force measuring rock points of the left and right hands and the left and right feet; The dynamic data of the triaxial force changing with time are further processed to obtain the key mechanical indicators of the left and right hands and the left and right feet in the action technique, including but not limited to: absolute hand grasping and foot extension peak force, relative hand grasping and foot extension peak force, vertical peak force, front-back peak force, lateral peak force, force growth rate, impulse, upper limb peak force ratio, upper limb average force ratio; Compare the key mechanical indicators of the three outside stepping techniques, use video recording to assist in analyzing the differences in the effects of the three movements, analyze the completion effects of the outside stepping techniques, and evaluate the technical level of the movements: Analyze which action technique is more labor-saving in the same rock point arrangement, how the triaxial force of the limbs changes, and form a rock climbing action characteristic data set; analyze whether the athlete's action technique is reasonable, and put forward suggestions for improvement to form an evaluation report. For the same hand and foot techniques, the maximum triaxial force of the right hand in the first test is 300N, and the maximum triaxial force in the second test is 120N. In the first action, the horizontal distance between the body's center of gravity and the fulcrum is far, so it is recommended that rock climbers pay attention to shifting the body's center of gravity to the left in this rock point environment. 9. The method according to claim 5, characterized in that the dynamic movement technique specifically comprises: The effective use of force in dynamic movement techniques is crucial. By increasing the time of force application to reduce the size of force, or using force to generate greater explosive force, the movement technique can be effectively used to achieve the moving goal. The key to dynamic movement is to apply force to the rock points at the beginning of the upper and lower limbs to generate acceleration of the human limbs, so that the human body leaves the rock wall and flies to the next group of rock points to achieve the effect of dynamic movement. In dynamic movement, the feet generate strong thrust, and the hands play the role of pulling and controlling the direction. When the body moves to a certain height, the opposite side of the grabbing hand needs to continue to push the hand point to the end. In this process, the longer the opposite side of the protective hand acts, the more the force time can be increased to increase the movement speed, which helps to increase the jumping distance. There are many types of dynamic movement techniques, including but not limited to: squat jump, one-hand squat jump, coordinated jump, gravity assist, zero and finger jump. All dynamic movement techniques are divided into three stages: take-off stage, air stage and wall fall stage. Whether the dynamic movement of rock climbers can achieve successful movement to the target rock point depends on the movement speed formed in the take-off stage and the spatial position of the next rock point; No matter what dynamic movement technique a rock climber uses, the power of dynamic movement is formed by the force of the feet and the force of the hands, and the movement of the body's center of mass always follows Newton's second law; According to the law of momentum, the momentum generated by the climber during the take-off phase is equal to the impulse received during this phase, and the impulse received by the climber during the take-off phase is the vector sum of the impulses generated by the climber using the pedals and the hands to pull the rock: (3) In the formula, It is the sum of the impulse vectors generated by the forces applied to the rock by both feet and hands. is the instantaneous body mass center velocity vector of the rock climber at the end of the take-off phase; Assuming that the climber is stationary when taking off, and the velocity of his center of mass is zero, the impulse vector is calculated according to the following formula: (4) In the formula, are the acting time of the force of the left foot, right foot, left hand and right hand during the take-off process, is the time-varying function of the force vector; A three-dimensional coordinate system Oxyz is established, where the origin O of the coordinate system is located on the stationary ground, and x, y, and z are the sagittal axis, coronal axis, and vertical axis of the body of the rock climber, respectively; At this time, formula (4) is orthogonally decomposed into three equations in three-dimensional space: (5) Combining formula (5) with formula (3), we can obtain the three components of the velocity of the center of mass of the rock climber after the take-off phase is completed: (6) In the formula, , , They are the center of mass speed of the rock climber at the instant of take-off and end of jump; The force vector data of the feet and hands in formula (6) are measured and obtained by the force sensor, and the center of mass velocity of the rock climber after taking off is calculated by digital integration through the pedaling force of the left and right feet and the pulling force of the left and right hands; After the rock climber completes the take-off action, he enters the air flight action. At this time, the rock climber is only affected by the gravity acting on the center of mass. The center of mass follows a parabolic motion trajectory. The coordinates of the center of mass during the body's air movement are Calculated according to the formula: (7) In the formula, , , They are the initial position coordinates of the center of mass of the rock climber’s body before taking off; If the climber grabs the next rock hold without considering it, the time from the air movement to the landing is calculated by the third sub-formula of formula (7), which is set to T; Furthermore, the rock climber adopts dynamic movement, the center of mass jumps from point A into the air, and uses the right hand to grab the target rock point C during the flight. The three-dimensional coordinates of point C are set as , the calculation formula for calculating the distance between the body center of mass and the target rock point C is: (8) During the parabolic motion of the center of mass in the air, the right hand needs to grasp the target rock point. During the motion, the distance between the center of mass of the body and the center of the right palm should be less than or equal to the length of the trunk plus the length of the right upper limb. Let the length of the trunk plus the length of the right upper limb be L ₀ ; By squaring both sides of formula (8), we get: (9) Deriving both sides of formula (9) and rearranging it, we get formula (10): (10) when When is the minimum value, there must be a function The derivative of is 0, as shown in formula (11): (11) Substituting equation (7) into the derivative term of equation (11) above, we obtain equation (12): (12) By numerically solving formula (12), we find When t _{min is the minimum value,} substitute t _min into formula (8) to calculate The minimum value _Lmin ; Finish The minimum value _Lmin in the 0~T stage is used to determine the change in the distance between the rock climber's center of mass and the target rock point, and to determine whether the rock climber has a chance to grab the target rock point. The result is determined according to the following discriminant: (13) The force measurement system is used to assess whether a rock climber can use dynamic movement techniques to jump from point A with a center of mass at point B to grab a target rock at point C, including: Measure and estimate the maximum distance L ₀ between the center of mass of the rock climber and the center of the right palm, and measure and calculate the initial coordinates of the center of mass before taking off in the mobile technique. , and the coordinates of the target rock point C ; The dynamic data of the three-axis force changing with time during the action are collected from the force sensor, including the dynamic data of the three-axis force changing with time on the four force measuring rock points of the left and right feet and the left and right hands. The center of mass velocity of the rock climber after taking off is calculated using formula (6), where the velocity in the x direction is calculated by the following method: (14) In the formula, To calculate the force measured by the force measuring system during the take-off process The numerical integration of the pedaling force in the direction over time is calculated as The impulse in the direction, is the time interval, m is the body mass of the rock climber; According to formula (14), , , Then, the dynamic changes of the center of mass trajectory coordinates of the rock climber's body during aerial motion are calculated using formula (7): ; According to formula (8), the dynamic change of the distance L(t) from the target rock point C during the rock climber's flight in the air is calculated. On this basis, the size of L(t) and _L0 is compared according to formula (13) to determine whether the rock climber can grab the target rock point C; In addition, when the human body jumps to the target rock point and leaves the rock point, there is no external force except gravity. At this time, the movement trajectory of the human body's center of gravity is a parabola. During the parabolic movement, one or both hands need to grasp the target rock point. During the movement, the distance between the body's center of gravity and the center of the right palm should be less than or equal to the trunk length plus the right upper limb length _L0 . Then, if the minimum distance _Lmin between the center of gravity parabola and the target rock point is greater than _L0 , the rock point cannot be grasped. The best action is to adjust the body posture and grasp the target rock point before and after approaching the minimum distance _Lmin between the center of gravity parabola and the target rock point. 10. The method according to claim 5, characterized in that the method further comprises: Evaluate the muscle activity and mechanical indexes of rock climbers during the three major movements of hand techniques, foot techniques and dynamic movement. For rock climbers to grasp and pinch one grasping point and two pinching points of different widths, analyze and evaluate the working characteristics and mechanical indexes of the relevant muscles, including: Stick electromyographic electrodes on the skin surface of the superficial muscles of the upper limbs and trunk related to grasping and pinching techniques; The athletes were tested for their subjective maximum strength of grasping and pinching three times using force sensors. During the test, the dynamic change data of triaxial force over time was obtained from the force sensors, and the surface electromyography signals of the superficial muscles of the upper limbs and trunk were synchronously collected through the surface electromyography system. The differences in technical indicators under the three rock holding conditions were analyzed, compared and evaluated. The indicator data were defined as follows: Absolute pinch grip peak force: the total traction peak when the climbers perform subjective maximum force pinch grip on the pinch point; Relative pinch grip peak force: the total traction peak relative to the body weight when the climbers perform subjective maximum force pinch grip on the pinch point; Vertical peak force, anterior-posterior peak force, lateral peak force: the traction peaks in each direction relative to the body weight when the climbers perform subjective maximum force pinch grip on the pinch point; Peak force ratio: refers to the ratio of relative pinch grip peak force to relative grip peak force, where relative grip peak force is the total traction peak relative to the body weight when the climbers perform subjective maximum force grip on the grip point; Peak force difference refers to the difference between relative grip peak force and relative pinch grip peak force; The average surface electromyography amplitude RMS, integrated electromyography iEMG and contribution rate of different muscles of the superficial muscles of the upper limbs were calculated, the activation degree of different muscles and the coordination relationship between different muscles, as well as the correlation between muscle activation characteristics and pinch grip strength were analyzed, and the level of individual athletes' technical movements was evaluated.