WO2019101737A1

WO2019101737A1 - Method for determining the force exerted by a person on a training device

Info

Publication number: WO2019101737A1
Application number: PCT/EP2018/081918
Authority: WO
Inventors: Wolfgang Goldammer; Izzet Cicek
Original assignee: Punch-It Gmbh
Priority date: 2017-11-24
Filing date: 2018-11-20
Publication date: 2019-05-31
Also published as: DE112018006000A5

Abstract

In a method for determining the force exerted by a person, in particular a person practising a combat-type sport, on a resilient training device, e.g. by impacting on the device using an extremity, such as the hand or the foot of the person, the applied force and/or introduced energy resulting from the extent of a deflection of the training device is determined from the physical properties of the training device, wherein the movement of the extremity of the person occurring in the direction of the training device is metrologically detected, at the latest, from the time of impact of the extremity on the training device to the time at which the movement occurring in said direction stops. The deflection of the training device is determined from the movement of the extremity of the person occurring between the two above-mentioned times, and the force exerted on the training device and/or the energy introduced into the training device is determined from the deflection of the training device.

Description

Method for determining the force effect

a person on a training device

1. Technical field of the invention

The invention relates to a method for determining the force of a person, in particular a person performing a martial art, on a restoring training device, e.g. by acting on the device by means of an extremity, e.g. the hand / fist or the person's foot.

In particular, the invention relates to the determination of the force effect and other impact parameters in martial arts via motion sensors in a device worn by the athlete on the body.

2. Background

When training for martial arts, the objectification of training progress - as in most sports - is of considerable importance. Essential training elements are punches or kicks on special training equipment (sandbags, maki waras, etc.), such as: B. in DE-A-10 2011 085 719 described. Here, it is desirable for the athlete to be able to objectively measure the strength of the beats (or kicks) as well as other parameters (eg frequency of beats or kicks per time interval) in order to compare with other athletes and to assess training progress and to be able to record.

So far, there is the possibility to use training pads equipped with pressure sensors, which can be used to determine and display the impact force. This has a number of disadvantages: • The measurement of the impact force is only possible for certain training sessions (punches or kicks on a fixed pad). When using many training devices (eg sandbags, maki waras) the impact force determination can not take place in this way.

• The determination of the impact parameters is limited to the impact force. Additional parameters such as the impact velocity can not be determined or (such as the frequency of impacts) only be determined with great effort.

• The determination of the beat parameters is not personalized for the athlete, but is only displayed in the training facility.

In addition, there are concepts for determining motion sequences and stroke parameters via devices equipped with acceleration sensors that are worn on the body by the athlete (eg boxing gloves with integrated sensors - see eg US-A-2014/0248594, US-A-2014 / 0372440 and US-A-2016/0263458). This allows the determination of the beat frequency and from the acceleration data the speed of the beat can be determined.

Without reference to the properties and material parameters of the training devices used, however, it is not possible to determine from these data the force actually exerted on the training device, since an immediate use of the law of force = mass x acceleration is not used to determine the exerted force Force can be used:

• The accelerated mass is not exactly definable (in addition to the hitting hand, a part of the body that can not be precisely defined is accelerated and decelerated during the stroke).

• An application of this formula would correspond to the imaginary case that an object (eg a ball) with the appropriate speed and mass is thrown against the training device and then braked. A determination of the force on this connection therefore neglects that during the beat, a further accelerating muscle force acts, which counteracts the delay by the training device. This additional muscle power is not taken into account in the above formula. The object of the invention is a method for determining the force of a person on a retractable training device, with which the force acting on the training device, and / or the energy that has been introduced into the training device, introduced more accurate can determine or let.

To solve this problem, a method is proposed with the invention, wherein

a retractable training device is provided, in which the force and / or applied energy resulting from the extent of a deflection of the exercise device from a rest position is known or determined from the physical properties of the exercise device, the movement of the extremity in the direction of the exercise device the person is detected by measuring at the latest from the time when the extremity hits the training device until the moment when the movement has taken place in the said direction,

From the movement of the extremity of the person between the two aforementioned times, the deflection of the training device and from the deflection of the training device the force exerted on the training device and / or the energy introduced into the training device are determined.

In an advantageous embodiment of the invention can be provided that the taking place in the direction of the training device movement of the extremity of the person is detected by measurement from the time of the beginning of the movement.

It can be particularly advantageous if the movement of the limb of the person is detected metrologically by means of at least one at least one-dimensional, preferably three-dimensional sensor, in particular displacement or acceleration sensor, gyro sensor and / or magnetometer.

It may also be expedient if the at least one sensor is worn by the person on their extremity acting on the exerciser. The disadvantages of the prior art are overcome by the method according to the invention, in which the impact parameters are not determined directly but indirectly via corresponding sensors. The parameters of interest (in particular the force exerted on the impact object) are determined from the sensor data on the use of physical relationship. In addition to the determination of the force acting during the impact or kick, these relationships also allow the calculation of the energy consumed by the athlete.

The inventive method is applicable to a wide range of training devices and requires for each training device only the definition of few calibration parameters (eg mass and length of the suspension of the training device, which is acted upon by hitting, such as sandbags, or spring constant , as in Makiwaras).

The data are collected and analyzed by a device equipped with motion sensors (so-called wearable) worn by the athlete on the arm or ankle depending on whether the force is to be measured in the arm or leg. Via a corresponding wireless communication, the data can be transmitted to a receiving device, where they are subjected to further evaluations, presented to the athlete, stored and optionally sent to a cloud.

3. Scope

The concept developed is applicable to all martial arts in which an athlete beats or kicks an object, the object resisting the blow or kick of its elastic properties or gravity. In these cases, the force applied to the object, the energy transferred, and other exercise parameters such as the frequency and total number of strokes or kicks can be determined. In Fig. 1 frequently used training devices are shown, in which the invention is applicable.

In Makiwaras (Figure la) or similar devices, the impact is against an elastic object (e.g., a board). This item is deflected by the blow over a certain distance d. The force required for this purpose results from the deflection d and the material properties, which are reflected in the spring constant K. The laws of energy = force x path also determine the transmitted energy.

Objects suspended on elastic supports (FIGS. 1 b and 1 c) correspond in their physical properties to maki waras and can be treated analogously.

In the case of a sandbag (Fig. Id), it is accelerated by the impact and likewise deflected by a distance d. From this deflection d, the transmitted energy can be determined, if mass M and length of suspension L are known. This energy allows conclusions to be drawn about the impact force and the transmitted energy.

4. Operating principle

The determination of the impact parameters takes place indirectly via an analysis of the impact movement (or the tread movement). This includes, on the one hand, the acceleration phase of hand or foot. When hitting the training device then creates a strong delay of the movement. The spatially and temporally resolved determination of the position and speed of the hand or foot during the impact movement, together with material parameters of the impact object, forms the basis of the evaluations, the methodology of which is specified below.

4.1 Determination of the time-resolved coordinates of the impact movement The target parameters to be determined initially during acceleration and deceleration of hand or foot are the time-resolved coordinates of the impact movement on the three spatial axes relative to the training device.

As a basis for their determination, the signals from the acceleration sensor at short time intervals on the order of e.g. Milliseconds supplied measured values of acceleration used. By means of a recalculation (integration) on the speed and further on the distance traveled by hand or foot, the impact movement can be described via time-resolved three-dimensional coordinate values:

• For each time interval, the vector of the distance traveled depends on the spatial initial position and the speed of the hand or foot at the beginning of the time interval.

• The change in the speed in the time interval is calculated from the acceleration values. The distance and velocity vectors thus determined then form the basis for evaluating the impact movement in the next time interval.

• The initial values for the spatial position and speed available before the start of the stroke can not be calculated from the acceleration data. From the retroactive calculation of the distance and velocity vectors during the entire impact movement, these initial values can be determined relative to the training device and this provides a sufficient basis for the further evaluations of the impact parameters. The starting point for this is the data obtained at the point of impact and reversal (see section 4.2).

Since a blow or kick in practice is not completely linear in the direction of the training device, an increase in the accuracy of the determination of the temporally resolved distance and velocity vectors can be achieved by determining the rotational movement via a gyrosensor in addition to the acceleration values via an acceleration sensor becomes. Moreover, to further increase the accuracy, there is the option, instead of or in addition to the Gyro rosensor to use a magnetometer. A further increase in accuracy can be achieved by using two motion sensors each designed for low or high accelerations and providing more accurate data in the various acceleration ranges occurring during the beat.

Overall, the measured values determined by the plurality of sensors can be used to more accurately determine the determination of the time-resolved three-dimensional coordinates of hand and foot as well as the respective speed during the beat.

4.2 Determination of the primary impact or kick parameters

In order to calculate the impact parameters, the following times must first be determined:

• beginning of the flapping motion;

• Impact time of hand or foot on the exerciser and

• reversal time at which the maximum deflection d (see Fig. 1) is reached.

These times can be determined from the time-resolved analysis of the impact or tread movement in accordance with Section 4.1:

• The beginning of the flapping motion can be determined from the beginning of the acceleration phase by hand or foot.

• The time of impact of the hand or foot on the exerciser is determined as the beginning of the delay.

• At the end of the stroke at the time of reversal, the direction of movement is reversed, which can also be read off the time-resolved three-dimensional coordinates of hand and foot.

The time points determined on the one hand form the basis of the determination of the beat frequency. On the other hand, the determination of the deflection d of the training between the point of impact and the point of reversal, the determination of the applied force and the transferred energy (see Section 4.3).

The concrete implementation of this analysis to determine the primary impact parameters can be done analytically by using the time resolved results from Section 4.2 on the basis of certain acceleration or deceleration thresholds to determine the different beat phases.

An alternative is to determine the temporal parameters of the blow or kick with artificial intelligence methods. The time-resolved acceleration data obtained according to section 4.1 can be used as input values of a neural network. Additionally or alternatively, values derived therefrom (speed and distance covered) can also be transferred to a neural network.

After appropriate training of the neural network with data on real beats, this can be used to detect all or some of the above. To determine impact parameters. This applies both to isolated punches or kicks as well as to series of punches or kicks from which an appropriately trained neural network can filter out the individual events and derive their primary parameters in the form of the times of the individual events.

An additional option for increasing the accuracy in determining the impact or kick parameters is to attach to the training object another device that is equipped with appropriate sensors (accelerometer, gyrosensor and / or magnetometer). By means of this additional sensor system, the deflections of the training devices caused by the impact or kicking movements in space can be detected in three dimensions and included in the analysis. The additional use of this data, especially with sandbags (see Fig. Id) and similar training devices that can freely oscillate on a suspension, can further improve the analysis accuracy of the mathematical methods described below, by determining the relative positions and occupancy. direction of movement of the blow hand or foot and training device are included in the assessment.

4.3 Determination of the applied force and transmitted energy

From the primary parameters of the impact or kicking movement, physical forces can be used to determine the force exerted on the exerciser as well as the transmitted energy (i.e., work done), which can be derived from the type of exercise:

• In the case of makiwaras or similar elastically designed or suspended exercise machines (see figures 1a to 1c), the force to be applied for the deflection d is the product of this deflection and the spring constant K:

F = K * d

The spring constant in this case represents a material parameter to be configured, the deflection d is determined according to the previous sections. The energy to be expended is determined in this case from the equation

E = ^1/2 * K * d ²

• For a sandbag, the force to be applied is the tangent component of the weight vector and the work done is the increase in potential energy. Both can be determined from the deflection angle f of the sandbag relative to the vertical. This deflection angle f results from the deflection of the center of gravity d _s and the length of the suspension from the ceiling attachment to the center of gravity L _s as f = 2 * arcsin (d _s / 2 * L _s )

Since the impact point of the impact or kick is not necessarily at the center of gravity, the deflection of the center of gravity d _s must be determined in accordance with determined by the multiplication by the ratio of the distance between the center of gravity L _s and the point of impact L _A of the suspension: d _s = d * (l_s / L _a )

From the deflection angle f thus determined, the mass of the sandbag M and the gravitational acceleration g then give the tangential component of the weight force to be expended as:

F = M * g * sin (f)

The energy to be expended results from the potential energy of the center of gravity at the deflection by the angle f to:

E = M * g * L _s * (l - cos (f))

Thus, in makiwaras or similar elastically responsive exercise machines, the implementation requires determination of the spring constant, which may be e.g. can be determined from a simple measurement of the deflection with a train scale for force determination. For sandbags, in addition to the generally known mass, the easily measurable distances between the center of gravity and the point of impact from the suspension are to be determined.

4.4 Examples of the technical realization

The sensors to be used (acceleration sensors and possibly other supporting sensors such as gyrosensor and magnetometer) are available as standard components in the form of integrated circuits (MEMS). They are arranged in a device G to be worn on the beating arm (or forearm or wrist) or impact foot (ankle) or associated leg (upper or lower leg) (see Fig. 2). The device is a wearable, such as fitness or activity tracker with the movement required for the invention. tion and / or acceleration sensors (preferably 3D sensors) or to a smartphone with such a sensor.

To evaluate the sensor data, these should be determined and analyzed with an accurate time resolution in the millisecond range. For this purpose, a corresponding timer is required in the device.

Furthermore, the analog data must be digitally transformed and then evaluated in a CPU. This is done either through analytic algorithms or in whole or in part by using a neural network, which is implemented via appropriate software tools in the CPU.

There must also be local memory for the program components and the necessary parameters. These include the basic parameters of the training equipment used. When using a neural network, these parameters also include the connection weights of the neurons determined by the learning.

In addition, there are other components for the power supply and display and control devices.

The start of the evaluation phases takes place either via buttons or touch-sensitive sensors in the body-worn device or via gesture control (for example, turning the wrist round to start a beat evaluation).

The data is processed in the device by software. When using a display device on the device, the core data of the analysis determined are immediately displayed to the user. In addition, there is the option of transferring the data to a base unit via a wireless communication link (eg Bluetooth) for further evaluation and use. The connection with a basic device can also be used to configure the basic parameters for the training devices. If an additional sensor-equipped device is used, which is attached to the training object, the measured data can be transmitted via a wireless communication link (eg Bluetooth) to the device worn on the arm or leg and then the summary evaluation can take place in this. Alternatively or additionally, a corresponding wireless communication connection with the base unit can also be set up for the transmission and summary evaluation of the data. On the base unit, the data can then be further processed, stored and compared with data from previous training units or other athletes via the use of appropriate aps. It is also possible to organize storage and comparison of analysis data over the Internet. 4.5 Summary

In the method according to the invention, the achieved deflection of the training device can be determined from the acceleration values and possibly further sensor information by determining the physical characteristics of the impact or kick. From the physical properties of the exerciser, the impact strength in Newton can be determined by means of calibration parameters (for example, mass and length of suspension for sandbags or spring constant for maki waras) by applying the appropriate physical laws. Additional parameters such as the beat rate and motion parameters, e.g. The recovery movement can also be determined by recalculation from the acceleration values. The energy transferred to the training object can also be determined from this data.

Claims

1. A method for determining the force of a person, in particular a person performing a martial art, on a retractable training device, e.g. by acting on the device by means of a limb, e.g. the hand or foot of the person, wherein the method provides a retractable training device, in which determines the force resulting from the extent of a deflection of the training device from a rest position and / or introduced energy from the physical properties of the training device becomes,

the movement of the extremity of the person in the direction of the exerciser is detected by measurement at the latest from the point in time at which the extremity hits the exerciser until the moment when the movement takes place in said direction,

From the movement of the extremity of the person between the two aforementioned times, the deflection of the training device is determined and from the deflection of the training device the force exerted on the training device and / or the energy introduced into the training device is determined.

2. The method according to claim 1, characterized in that the taking place in the direction of the training device movement of the extremity of the person is detected by measurement from the time of the beginning of the movement.

3. Method according to claim 1, characterized in that the movement of the extremity of the person is based on at least one at least one-dimensional, preferably three-dimensional sensor, in particular displacement or acceleration sensor, gyrosensor and / or magnetometer, metrologically recorded.

4. The method according to claim 3, characterized in that the at least one sensor is carried by the person on the extremity acting on the exerciser.

5. The method according to claim 3 or 4, characterized in that by at least one attached to the training object additional sensor with appropriate functionality as the extremity carried at least one sensor, the movement of the training device relative to the movement of the force acting on the exerciser limb metrologically detected and taken into account for determining the force exerted on the training device and / or the energy introduced into the training device.