WO2001066196A2

WO2001066196A2 - Commodity

Info

Publication number: WO2001066196A2
Application number: PCT/CH2001/000372
Authority: WO
Inventors: Franz Kornfeind
Original assignee: Franz Kornfeind
Priority date: 2001-06-14
Filing date: 2001-06-14
Publication date: 2001-09-13
Also published as: WO2001066196A3; AU2001263700A1

Abstract

The invention relates to a commodity which is subjected to a mechanical-dynamic stress in a predetermined zone when used by a user, the corresponding stress being a function of the individual technique of use, as for example a training shoe (10) and the compressive stress exerted on its sole/heel zone (B1, B3). The inventive item is provided with an array of mechanical stress sensors (5) that registers the dynamic stress in the zone of interest (B) and stores the same.

Description

Commodity

The present invention relates to an article of daily use which is mechanically and dynamically loaded by a user in a predetermined range during use, and this loading is a function of the individual use technique in each case.

Such articles of daily use include, for example, articles of daily use from the field of sport, such as sports shoes, in particular jogging shoes, soccer shoes, shoes for athletic running and

Jumping disciplines, further racquets of all kinds, such as and in particular tennis racquets, squash racquets, badminton racquets or table tennis racquets, further golf clubs, hockey sticks, boxing gloves, oars, rapiers, swords and sabers, spears,

Discs, balls, sticks and skis for Nordic and Alpine disciplines, snowboards, polo bats, baseball bats, pole vaulting sticks, billiard sticks etc.

When using all of these items, the individual technique is reflected, among other things, in the mechanical stress that the item experiences when used by a viewed individual. The same applies if necessary to objects outside the sports area, such as organ or piano keyboards, to name just one example.

Very often, when such objects are used individually, there is a need to quantitatively record the respective individual technology in order, for example in the context of a training session, to quantitatively visualize the individual's technology with any deficiencies that may still be present lead, intervene correctively or to encourage motivating.

It is an object of the present invention to create a commodity of the type mentioned above, by means of which the respective mechanical usage load can be shown quantitatively - usually dynamically in time - in real time or at any later point in time.

For this purpose, the object of use mentioned at the outset is characterized in that an arrangement of mechanical load sensors is installed in the specified range.

In a first preferred embodiment of the article of daily use according to the invention, the electrical output of the arrangement of mechanical load sensors is operatively connected to the input of a storage unit on the article. With that the

The exposure history that the object experiences during use by the individual is stored on the object itself for subsequent evaluation. It should also be borne in mind that the mechanical-dynamic loads on the object are extremely slow compared to the electronic signal processing speeds that are already possible today. For example, the current data processing speeds with rates of 500 MHz and above should be pointed out. Therefore, it is entirely possible, according to a further preferred embodiment of the article of use according to the invention, to effectively connect the output signal of the arrangement of mechanical load sensors to a transmitter unit on the article of use and the to transmit the electrical output signal of the arrangement corresponding data, to receive it at a corresponding receiver unit, if necessary to store it temporarily and to evaluate it, detached from the commodity, such as on a clock.

In a further preferred embodiment variant of the commodity, to which the output of the arrangement mentioned is operatively connected to the input of a storage unit on the object, the output of this storage unit is to an evaluation unit

Display unit, still on the object, guided. This makes it possible, for example after the training has been carried out, to visualize its course directly on the basis of the load history shown, with the evaluation unit being used to carry out the visualization, object-specific, as user-friendly as possible.

In a further preferred embodiment of the commodity according to the invention, in which the

Output of the arrangement is operatively connected to a storage unit on the commodity, its output is routed to a tap output on the commodity, so that the commodity can be connected to a computer, for example after training has taken place, and, based on the stored load history, the training sequence and - success can be visualized with individual technology.

In a further preferred embodiment of the commodity according to the invention, in which the storage unit is integrated on the commodity, the latter is designed to be manually resettable, preferably by entering a code. So that will achieves that only the person who has the code, for example the trainer or teacher, can reset the memory unit and it is ensured that this only takes place after an evaluation of the training that has taken place has been carried out.

In particular in the preferred case in which the output of the arrangement of mechanical load sensors is operatively connected to a storage unit on the commodity itself, a timing unit is also provided on the commodity, which is connected to the

Write control input of the storage unit is operatively connected. Also in the sense of a reduction in the amount of data, the timing unit specifies a storage rate for the signals appearing on the output side of the arrangement mentioned, which rate - as is known to the person skilled in the art - according to the

Dynamics of the expected loading processes on the specific commodity.

Furthermore, it is preferably proposed to control write processes on the memory unit by achieving a characteristic behavior of at least part of the load detected by the arrangement.

If one looks at the objects of use mentioned at the outset, mechanical loads of interest only occur for a very short time, while in other time phases the object is not loaded. A typical example of this is a tennis racket or a sports shoe. Therefore, in many cases it makes little sense to store the output signal of the above-mentioned arrangement continuously at a predetermined time cycle if no significant signals or data appear at all over relatively long periods of time. This will be like mentions thereby resolved that the signal storage is only released when at least part of the mechanical load detected on the arrangement reaches a predetermined state. In a preferred embodiment of the latter-mentioned implementation variant of the inventive

Utility object is proposed for this purpose to operatively connect at least some of the signals from the output of the arrangement to a differentiation unit, the output of which is operatively connected to the input of a threshold-sensitive unit. The output of the threshold-sensitive unit controls the operative connection of the timing unit with the write control input or the write input of the memory unit. In many cases of stress on the mentioned

Commodities, namely the onset of relevant load periods by a given change in time of the load mentioned and also the end of such a load phase of interest. For this purpose, reference is made, for example, to a sports shoe, a tennis racket or a golf club, where the onset of a stress period of interest can be detected by an extremely rapid increase in stress over time. In a far preferred embodiment of the article of daily use according to the invention, the output of the arrangement of mechanical load sensors is operatively connected to the input of an analog / digital converter arrangement. This both in the case where the storage unit for the signals appearing at the output of the arrangement mentioned on the commodity itself is provided, as well as in the case where the signals mentioned are transmitted from the commodity via wireless transmission to a remote receiving unit via a transmitter unit and are only there evaluated.

In any case, it is proposed to convert the analog signals on the output side of the arrangement as digitally as possible and then to carry out the signal processing digitally. Furthermore, it may well be appropriate to interpose a time-domain / frequency-domain converter unit between the output of the arrangement mentioned and the input, in particular of an evaluation unit provided on the object, and to carry out the signal evaluation in the frequency domain. This may facilitate the

Computational effort for the evaluation is considerable, especially taking into account that fast miniaturized time domain / frequency domain converters (FFT) are definitely part of the state of the art today. In a further preferred embodiment of the commodity according to the invention, with the aim of integrating as little electronics as possible, it is proposed to provide the storage unit on the object that is operatively connected to the output of the arrangement, such that, for example, after the

Training the storage unit, for example in the form of a memory chip, removed from the commodity and, separated from it, can be supplied to the evaluation on a computer. Furthermore, it is entirely possible to first effectively connect the output of the arrangement to a storage unit and only to connect its output to the input of a transmitting unit for wireless communication on the consumer article according to the invention, so that, in the sense of temporary storage, independence between the wireless transmission rate and the occurrence of information at the output of the mentioned arrangement is effected.

Although a large number of articles of daily use, which may be designed according to the present invention, are already open to the person skilled in the art from the preceding explanations, specific ones of these articles according to the invention are specifically proposed. Thus, a preferred embodiment of the commodity mentioned is a string-covered racket, on which the sensor arrangement is formed on the one hand by at least part of the stringing strings and on the other hand by tension sensors that are operatively connected to these strings and integrated in the racket frame. The structure corresponding to Cartesian coordinates on a racket covered with a network of essentially orthogonal strings is exploited in that the arrangement is formed by two sets of mutually substantially orthogonal strings and sensors assigned to them, and the current load at a point on the racket surface by assignment of a one string of both sets takes place simultaneously.

Furthermore, it is proposed in the preferred embodiment of the object according to the invention as a racket that two of the rackets forming the object are provided, each with synchronously running timekeepers, and one each the arrangement of mechanical load sensors downstream evaluation unit evaluates the temporal load sequence taking place on the two rackets in a time-synchronized manner. This makes it possible to assess the reaction following the beat of a racket with a corresponding load on the other racket.

In a further preferred embodiment of the article of daily use according to the invention, it is formed by a golf club, to which the arrangement of mechanical load sensors is attached in the event of the club head being subjected to a stress area. If necessary, an arrangement of the mechanical load sensors can be provided, in particular in the case of these embodiments as a golf club or, as mentioned above, as a racket also on the club neck or racket handle, then preferably with bending sensors or torsion sensors, the output signal of which is representative of the accelerations experienced when the swing takes place. In a further preferred embodiment of the object according to the invention, it is a running or jumping shoe and the arrangement of mechanical load sensors provided according to the invention is installed in the area of the ball of the foot and possibly the heel in the area of the shoe sole. If the shoe is one

Football shoe, the arrangement of mechanical load sensors provided according to the invention is preferably installed in the area of the tip of the foot in order to register information about the ball treatment. In a further preferred embodiment of the object according to the invention, it is replaced by a Hockey stick formed, and the arrangement of mechanical load sensors provided according to the invention is preferably installed in the transition area between stick and blade. Is it like a further preferred embodiment of the invention

Commodity around a boxing glove, the arrangement provided according to the invention is installed in the latter in the punching area of the glove. Is it like another preferred

Embodiment of the present invention, around a foil, a rapier or a saber of the corresponding fencing sports, the arrangement of mechanical load sensors provided according to the invention is installed in the tip and / or, in particular in the form of bending sensors, on the blade.

As mentioned, the present invention is suitable, as is now readily apparent to the person skilled in the art, for a large number of other everyday objects of the type mentioned at the outset, such as for spears of javelin disciplines, bows for archery disciplines, skis and poles for alpine and Nordic disciplines, polo bats, baseball bats, Pole vaulting sticks, billiard sticks, oars etc. As is readily apparent to the person skilled in the art, the arrangement provided according to the invention becomes more mechanical

Load sensors installed on the relevant parts, especially where the load is significant for the individual technology. Regarding the evaluations made, it can be stated that, depending on the object of use, all sizes can be determined and displayed, which result from the measured Allow pressure loads to be derived. These can be integral sizes such as work steps performed or number of strokes etc. On the other hand, courses, directions (tennis) etc. can also be determined and displayed as a function of time, just to name a few examples. The invention is subsequently explained, for example, using figures. These show:

Fig. 1 schematically and simplified, a utility object according to the invention in the form of a running shoe, to explain the basic principle of the invention;

Fig. 2 over the time axis, purely for example, the

Course of mechanical stress when using the object according to the invention according to FIG. 1; 3 schematically, the basic concept of the present invention, in a first embodiment;

Fig. 4 in a representation analogous to that of Fig. 3, a second basic principle;

Fig. 5 in a representation analogous to that of Figs. 3 and 4, simplified, a preferred

Realization form of a commodity according to the invention;

6 schematically, simplified, the structure of a racket according to the invention; 7 in the form of a simplified signal flow / function block diagram, the evaluation system for the synchronized evaluation of the load data registered on a pair of objects according to the invention designed as rackets, and 8 simplified and schematic, an object according to the invention designed as a golf club.

1 shows a commodity according to the invention, namely using the example of a jogging shoe 10. If you look at the area of the sole in the

Foot area and area B ₃ in the heel area and the dynamic pressure loads p _x ι (t) - p _x β (t) that result locally at Xi to xs when running with the shoe 10, result in load profiles as they are - without claim to Accuracy - qualitatively and partially shown in Fig. 2. These courses and their time sequence correspond to the time-dynamic pressure distribution in the examined areas Bi and B ₃ and are, individually, dependent on the running technique. They are the basis for assessing an individual's running style and technique.

As shown schematically in FIG. 3, an arrangement 5, each with at least one mechanical load sensor 7, is installed on the utility object 10 according to the invention, for example the running shoe according to FIG. 1, in a predetermined region B of load p or load distribution of interest. Depending on the extent and type of area B, a plurality of load sensors 7 are arranged as a sensor matrix. Depending on the load, pressure sensors, tension sensors, bending sensors, torsion sensors etc. can be provided, if appropriate on an arrangement 5, appropriately, mixed.

In the arrangement according to the invention shown in FIG. 3, the electrical output A _{5 of} the arrangement 5 of mechanical load sensors 7 on the utility object 10 is led to the input E _{9 of} a storage unit 9. This is preferably done with a dashed line Analog / digital converter arrangement 11. If, as in the case of the running shoe according to FIG. 1, a plurality of load sensors 7 are provided on the arrangement 5 according to FIG. 3 and are installed at different locations along area B, the local, respective load in two or even three dimensions, as shown with p _xy , registered and, additionally, in each case as a function of time t.

By registering the electrical output signals E (p _xy (t)) on the storage unit 9, the

Load history registered. By evaluating these load profiles, knowing their place of occurrence - based on the fact that the locations of the individual sensors 7 on the utility object 10 are known - the individual technique of using the aforementioned utility object can therefore be reconstructed and visualized.

If the storage unit ah has been stored on the utility object 10, the evaluation and visualization can likewise be carried out on the utility object 10. This makes the utility object independent of external units. Otherwise, however, the content of the storage unit 9 can be read out from the object 10 and, separated from it, evaluated and displayed. Another option, which is particularly useful when the object is only very small and subject to high loads, is to design the memory unit 9, for example interchangeably, for example as an interchangeable memory chip, and to read it out from the everyday object, to evaluate it and to visualize the result accordingly. FIG. 4 shows, again schematically, a further basic embodiment variant of a utility object 10a according to the invention, such as, for example, a running shoe according to FIG. 1. Here, at the output of A5 5 generated electric signals S ₅ itself does not, or not necessarily, stored the array, but to the modulation input supplied Mod a transmitter unit 11 and wirelessly therethrough, preferably by radio, to a (not shown) from the object to be 10 remote unit with appropriate receiver and decoder transmitted. In the embodiment according to FIG. 4, however, the signals occurring at output A ₅ are also temporarily stored before they are transmitted to transmitter unit 11 for wireless transmission via an antenna arrangement 13 shown schematically in FIG. 4. Here too, the signals fed to the mod input are preferably digitized.

With this procedure, the sensor output signals can be transmitted in a time-sequential manner, and their temporal overlap is only created again at the receiving end during the evaluation (see FIG. 2).

Based on the basic principle according to FIG. 3, ie with the storage of the electrical signals S ₅ appearing at the output A _{5 of} the arrangement 5, a preferred implementation is shown schematically simplified in FIG. 5.

At least some of the output signals of the arrangement 5, S5 ^"are checked to determine whether the corresponding load reaches a predetermined state. According to FIG. 5, this is checked on the basis of the time derivative of the signals S5- at a differentiation unit 15. The For this purpose, the output signal of the differentiation unit 1-5 is further fed to a threshold-sensitive unit 17, to which at least one, as shown two, threshold value signals W _E and W _s are fed. If the time derivative of one or the signals S ₅ ^~ exceeds the threshold value W _E , the threshold-value-sensitive unit 17 triggers a switching unit 19 on the output side, which creates the operative connection between the output of the arrangement 5 and the write input E _{9 of} the memory unit 9. The subsequent signal values of the memory unit 9 are thus only written in when the threshold value given by W _E is reached by the time derivative of at least a portion S ₅ ^{~ of} the output signals S _{5 of} the arrangement 5. This is done clocked by a clock generator 19, the output of which

Write control input T of the memory unit 9 is supplied. Of course, and preferably, the control of the active connection between output A ₅ and the memory unit 9 can be controlled by the output of the threshold-sensitive unit 17 by enabling or disabling the write clock signal

Control input T take place, as shown in dashed lines.

There, in freely activated time segments, in time with the clock generator 19, the signals prevailing at output A ₅ are sampled sequentially and the

Storage unit 9 registered. If the storage unit 9 is permanently installed in the everyday object 10, its readout output A9 is routed to a connection provided on the object 10, for example a plug connection 21. The read control input L of the memory unit 9 is connected to a further connection 23, so that it is external, possibly also clocked externally via connection 23, the content of the memory unit 9 can be read out for further external evaluation.

As shown in dashed lines in FIG. 5 as an alternative or supplement, one can be on the everyday object 10 itself

Evaluation unit 25 and a display unit 27, such as an LCD screen, can be integrated. In this alternative, the output A _{9 of} the memory unit 9 is led to the input E _{25 of} the evaluation unit 25. Of course, both variants, namely readability of the

Storage unit 9 at the connection 21 and evaluation and display on the everyday object 10 itself can be combined.

Furthermore, a reset circuit is preferably provided for the memory unit 9. For this is the

Reset input R of memory unit 9 is operatively connected to output A _{29 of} a comparison unit 29. On the one hand, this is entered, preferably manually, on an input unit 31, a reset code which is compared on the comparison unit 29 with a code previously stored on a unit 33. If the two codes match, the memory unit 9 is reset via the reset input R.

A large number of different possibilities are likely to open up to the person skilled in the art, starting from the explanations in FIGS. 1 to 5, to implement the registration, evaluation and display of the individual load profiles on which the invention is based. Subsequently, only two preferred consumer articles equipped according to the invention are presented for example. In Fig. 6, a commodity according to the invention, namely a racket, is shown schematically. The racket, for example a tennis racket, a squash or badminton racket, has a string covering with horizontal 35 _h and vertical 35 _{v /} string strings which essentially cross at right angles.

The frame 37 of the racquet stringing strings 35 are _v and 35 _h on at least one side, for example, designed as piezo elements tension sensors 39 and anchored _v _h. 39 The two sets of

Tension sensors 39 _v and 39 _h according to the invention and, in a preferred embodiment, are guided to the storage unit 9 integrated on the racket, for example in the handle portion thereof. If one describes the string direction h as the x direction and the other v as the y direction, it can be seen that the string strings define the lattice of a right-angled coordinate system. The respective vertical strings 35 _v define the x coordinate values, the horizontal strings 35 _h the y coordinate values of a point Q (x ₀ , Vo) of the stringing. _Utilizing this grid structure, schematically shown in FIG. 6, the outputs A _3gv on the storage unit 9 _define storage _columns , the outputs A _39h storage _rows .

At stressed stringing points, one of the strings 35 _v and one of the strings 35 _h are stressed simultaneously. This simultaneity makes it possible in each case to store a loading value in the corresponding column and row of unit 9, with which the loading location is also registered on the clothing. Since only one value is stored in the intersection of the row and column and the sensors under consideration 39 _v , 39 _h Probably at the same time, but not necessarily showing the same load values, an average value is preferred

S (p _xy (t _n )) - S _39v + S _39h

2 saved.

This procedure allows the load on a surface to be recorded with far fewer sensors than would be necessary to selectively load the surface on this surface with a

Capture sensor matrix. Instead of (n x m) sensors, only (n + m) sensors are required.

Otherwise, the racket according to the invention is preferably designed as explained with reference to FIG. Evaluation unit 25 and display unit 27 are integrated in the handle of the racket (not shown). If a stringing area is pressurized by hitting a ball, the stringing strings and tension sensors affected define the striking area on the one hand and, on the other hand, enables e.g. the difference in the mechanical stresses of adjacent covering areas an evaluation of the angle, the energy, etc., at which the ball hit. Of course, here too, if necessary via a

4, ie a wireless data transmission is created between the respective rackets and a stationary evaluation and display station set apart from them. In order to be able to evaluate the mutual reactions in a partner game played by means of a racket, for example according to FIG. 6, ie the reaction to a hit made, the stress data of both rackets can, as shown schematically in FIG. 7, jointly apply to one

Evaluation unit 41 are given, be it by reading out the respective storage units, be it by wireless data transmission or be it by removing the storage units 9, for example in the form of a chip, and reading them in at the central evaluation unit 41. By integrating synchronized timers in the two rackets 10b, 10c , as symbolized in FIG. 7 with t _c = t _b , it becomes possible without further ado to record the chronological sequence of the stresses that have occurred in each case.

8 schematically shows the implementation of a further utility object according to the invention, namely a golf club 10d. Here, the arrangement 5 of mechanical load sensors 7 is installed in a matrix-like manner on the face F of the golf club head. It is

(not shown) a permanently installed memory unit with readout connections according to 21 of FIG. 5 is provided, an expandable memory chip, or an evaluation unit and display are integrated on the golf club, as with a display 43 according to FIG. 8 Handle of the golf club 45 - possibly also on the handle of the racket according to FIG. 6 - built-in bending and torsion sensors in order to detect the deflection or torsion occurring during the impact acceleration and to determine the impact characteristics from this by appropriate evaluation. In all the embodiment variants shown, it is advisable to carry out the evaluation of the output signals of the arrangement 5 digitally, for which purpose, in a manner known to the person skilled in the art, an analog / digital converter arrangement is interposed, as shown in FIG. 3, in the sensor arrangement and the evaluation unit. If appropriate, it can also be advantageous to carry out the evaluation of the time signals in the frequency range in accordance with the registered dynamic load profiles, for which purpose, in a likewise known manner, the

Evaluation unit is connected upstream of a time domain / frequency domain converter unit (not shown), possibly followed by a frequency domain / time domain converter unit downstream of the unit mentioned. From the load time profiles and their location assignment, variables such as speed, energy, point of impact, direction of impact, acceleration etc. can be determined specifically for the respective commodity according to the invention and can be displayed in a manner that is easy to interpret for the user.

Claims

Claims:

1. Utility object, which is mechanically and dynamically loaded by the user in use in a predetermined area and this loading is a function of the respective individual usage technology, characterized in that an arrangement of mechanical load sensors is installed in the area.

2. Utility object according to claim 1, characterized in that the electrical output of the arrangement is operatively connected to the input of a storage unit on the object.

3. Utility object according to one of claims 1 or 2, characterized in that the output of the arrangement of mechanical load sensors on the object is operatively connected to a transmission unit for wireless data transmission.

4. Commodity according to one of claims 1 to 3, characterized in that the output of the arrangement of mechanical load sensors is operatively connected to the input of a storage unit on the commodity, the output of which is operatively connected via an evaluation unit to a display unit on the object.

5. Utility object according to one of claims 1 to 4, characterized in that the output of the arrangement is operatively connected to the input of a storage unit on the utility object, the output of which is led to a tap on the object.

6. Commodity according to one of claims 1 to 5, characterized in that the output of the arrangement with the input of a storage unit on the commodity is operatively connected and the memory unit can be reset manually, preferably by entering a code.

7. commodity according to one of claims 1 to 6, characterized in that the output of the arrangement of mechanical load sensors with the input of a

Storage unit is operatively connected to the commodity and the output of a timing unit with a write control input of the storage unit.

8. Utility object according to one of claims 1 to 7, characterized in that the arrangement is mechanical

Load sensors on the output side are operatively connected to the input of a storage unit and a unit for detecting a predetermined or predeterminable state of at least some of the signals is provided at the output of the arrangement mentioned, the output of which blocks or enables write operations on the storage unit.

9. Utility object according to claim 8, characterized in that at least a part of the signals occurring at the output of the arrangement of mechanical load sensors is operatively connected to a differentiation unit, the output of which is operatively connected to the input of a threshold-sensitive unit, the output of which blocks or enables the write operations on the memory unit ,

10. Utility object according to one of claims 1 to 9, characterized in that the output of the arrangement of mechanical load sensors is operatively connected to the input of an analog / digital converter arrangement.

11. Utility object according to one of claims 1 to 10, characterized in that the output of the arrangement mechanical load sensors and the input of an evaluation unit, a time domain / frequency domain converter unit is interposed.

12. Utility object according to one of claims 1 to 11, characterized in that the output of the arrangement of mechanical load sensors is operatively connected to the input of a storage unit on the object and the storage unit on the object is replaceable.

13. Utility object according to one of claims 1 to 12, characterized in that it by a stringed

Racket is formed, on which the arrangement is formed, on the one hand, by at least some of the strings and, on the other hand, tensile sensors integrated in the racket frame and in operative connection therewith.

14. Utility object according to claim 13, characterized in that the arrangement of mechanical load sensors is formed by two sets of mutually orthogonal string strings and tension sensors assigned to them.

15. System with two of the commodities according to one of claims 13 or 14, characterized in that a synchronized time measurement is carried out on the objects and the outputs of the arrangement of mechanical load sensors provided on the objects are operatively connected to a common evaluation unit, to which the load evaluation occurred in the temporal sequence is evaluated on the two objects.

16. Utility object according to one of claims 1 to 12, characterized in that it is formed by a golf club, by which the arrangement mechanical Load sensors are attached in the ball-impact area of the club head.

17. Commodity according to one of claims 13 to 16, characterized in that a further arrangement of mechanical load sensors is attached to the handle of the commodity, preferably with bending and / or torsion sensors.

18. Utility object according to one of claims 1 to 12, characterized in that it is a running, jumping or soccer shoe or one

Hockey stick or a boxing glove or a foil, a sword or a saber.

19. System with at least one commodity according to one of claims 1 to 14, 16 to 18 or a system according to claim 15, characterized in that the output of the arrangement of mechanical load sensors can be operatively connected to an evaluation unit via a wireless transmission link.