US20050215335A1

US20050215335A1 - Position detector and method of motion analysis

Info

Publication number: US20050215335A1
Application number: US10/954,711
Authority: US
Inventors: Christian Marquardt
Original assignee: Individual
Current assignee: Individual
Priority date: 2004-03-26
Filing date: 2004-09-30
Publication date: 2005-09-29
Also published as: EP1727602B1; ATE513598T1; WO2005094949A1; EP1727602A1

Abstract

The invention relates to a position detector (3) for a method of motion analysis, especially for golf training. It is proposed that the position detector (3) be detachably mounted on a ball sport device (2) and then receive and transmit at least one position signal for the determination of the spatial position and/or the alignment of the ball sport device (2). Furthermore, the invention includes a method of motion analysis by using the position detector according to the invention.

Description

The invention relates to a position detector, as well as to a method of motion analysis.
In the game of golf, putting requires highly-developed fine motor skills from the players. During training, primary attention is normally focused on the driving technique, that is, on the static aspects of motion. During putting, the dynamics of motion can hardly be perceived with the naked eye due to the extremely low execution speed. Likewise with conventional methods of analysis, such as video analysis, the dynamic aspects of putting movements have, for methodological reasons, been analyzable only unsatisfactorily and with great difficulty. Correspondingly, the training of the short game is often quite neglected and frequently leads to unsatisfactory results, although putting makes up approximately 40% of the golf game when measured by the number of strokes.
The task of the invention is therefore to measure and improve the sequence of movements during the golf game, and especially during putting.
This task is accomplished by means of a position detector according to claim 1 and by a corresponding method of motion analysis according to claim 18.
The invention is based on the knowledge that, when learning slow movements such as putting, unnoticed systematic motion errors are also frequently learned. The execution of quick ballistic motions is always purely motor-driven and, therefore, self-organizing. In contrast to this, the execution of slow motions is always closely tied to strategy. Strategic motion errors during slow motions, such as those performed during putting, frequently go unnoticed by the golfers themselves; and it is difficult even for trainers to recognize these mistakes with the naked eye. For example, in the sport of golf, the so-called Yips syndrome leads to an unconscious twitching of the hand and wrist during the short game and thus makes precise execution of the swinging motion impossible. Yips syndrome cannot be alleviated with conventional training methods; quite the contrary, the symptoms continue to worsen with intensified practice.
The invention therefore comprises a general technical gauge for recording and analyzing the movement of a golf club using a suitable device-supported method of motion analysis. The strengths and weaknesses of the individual sequence of movements are hereby, on the one hand, displayed in detail, enabling targeted, and thus extremely efficient, training. Furthermore, motion problems, such as the Yips syndrome, can be measured early and objectively. By using the derived information, a specific treatment for these motion problems can be carried out for the first time.
In addition to this, within the framework of the invention, a position detector is provided that is detachably mounted on a golf club for the purpose of determing the spatial position and/or the alignment of the club.
Preferably, the position detector receives and transmits at least one position signal, which serves to determine the position and/or the alignment of the golf club.
The invention is not, however, limited to recording the position or alignment of a golf club, but can rather basically be used for other ball sport devices, such as, for example, billiards, cricket bats, or similar clubs. To facilitate understanding, however, the invention will be described below using a golf club.
The position detector is preferably an active position detector that transmits at least one position signal that is recorded by a stationary receiver, wherein the position and/or the alignment of the golf club is determined by the receiver dependent upon the received position signal.
Another alternative, however, is a position detector, mountable on the golf club, that is passive and has a receiver for receiving a position signal from a stationary transmitter, wherein the position and/or the alignment of the golf club is again determined by the receiver dependent upon the position signal.
The position signal is preferably an ultrasonic signal that, for example, can be transmitted with a measurement rate of between 100 Hz and 400 Hz, wherein the measurement rate in the preferred embodiment of the invention amounts to 300 Hz. The use of an ultrasonic signal as the position signal enables a high-sensitivity resolution of approximately 0.1 mm, which, during motion analysis, can expose the smallest details of the sequence of movements and also enable the identification of motion disturbances, such as, for example, Yips syndrome, which are invisible to the naked eye.
With regard to the position signal, however, the invention is not limited to an acoustical signal. The position signal can rather be an optical or a magnetic signal. In this regard, the motion-measuring components can—for example, according to the principle of optical position determination—consist of cameras or laser-light scanning; and the measuring sensors can be made of reflecting and/or actively ruminating marking dots and optically sensitive measuring surfaces. Furthermore, according to the principle of position determination, the motion-measuring components can function by using magnetic fields.
In addition to this, the position detector can also have one or more acceleration sensors that record the movement of the golf club.
In the preferred embodiment of the invention, the position detector that can be mounted on the golf club has at least three transmitters or receivers, so that the position of the individual transmitters or receivers can be precisely determined by triangulation and subsequently coordinate transformation. The individual transmitters or receivers are hereby preferably arranged on a common plane and form a triangle.
Furthermore, it is preferable for the individual transmitters to emit essentially in the same direction, wherein the individual transmitters can have a transmission angle of up to 180°, so that the position detector or an associated control unit must be only approximately aligned with the associated receivers.
When the position detector is in the mounted state according to the invention, one of the transmitters is preferably arranged flush with the shaft of the golf club, while the other two transmitters are arranged on opposite sides of this plane. This arrangement of the individual transmitters advantageously enables a simple and precise coordinate transformation and, thus, precise position determination.
The position detector according to the invention is preferably mounted on the shaft of the golf club, wherein the mounting is detachable and, for example, can be performed with a clamping screw joint. The position detector is hereby preferably rotatable around the shaft of the golf club, wherein a gauge can be used for aligning the position detector in the rotation direction relative to the golf club.
The detachable mounting of the position detector according to the invention that is on the golf club is advantageous because the position detector is also a training device, and different golf clubs can be compared to one another. For example, testing different golf clubs with the position detector according to the invention enables the direct selection of the individually optimal golf club, which otherwise is possible only with a longer use of different golf clubs.
The actual determination of the position or alignment of the golf club is hereby preferably performed via a stationary control unit, wherein the control unit is connected to the transmitters and the receivers in order to perform a transit time measurement and thus determine the position and alignment of the position detector and the golf club to which the position detector is attached. A conventional control unit, such as, for example, the one marketed by zebris Medical GmbH, Max-Eyth-Weg 42, 88316 Isny (Germany) under the brand name CMS-20 or CMS10, can be used for this.
Within the framework of the method of motion analysis according to the invention, the raw data from the aforementioned, well-known control unit, however, undergoes a kinematic analysis in order to acquire golf-specific information on golf training and, particularly, on the training of putting. For example, from the position and/or the alignment of the golf club, the following swing parameters can be determined:

- duration of backswing
- duration of follow-through
- impact time
- symmetry of the impact time
- symmetry of the velocity profile
- alignment when addressing the ball
- club head at the moment of impact
- differential value for alignment
- rotation to the moment of impact
- rotation after the moment of impact
- rotation rate per time
- horizontal angle of the club head on the swing path
- loft of the club at the moment of impact
- point of impact on the club head
- height of club at moment of impact
- length of backswing
- length of follow-through
- symmetry of swing path
- horizontal direction of the swing path at the moment of impact
- vertical incline of the swing path at the moment of impact
- maximum backswing velocity
- velocity at impact
- maximum follow-through velocity
- maximum acceleration
- acceleration after impact
- maximum braking
- average jerk during the backswing
- average jerk during the follow-through.

Additionally, within the framework of the method of motion analysis according to the invention, the variabilities of all twenty-eight (28) parameters are preferably calculated for multiple swings (typically, 5 swings), in order to describe the consistency of motion execution.
Furthermore, the individual swing parameters are preferably normalized within the framework of the method of motion analysis according to the invention, so that deviations from the norm within the individual swing parameters can be easily recognized and quantitatively evaluated.
In addition to this, the swing parameters are preferably graphically depicted within the framework of the method of motion analysis according to the invention, wherein the depiction can be performed with stored comparative values so that deviations and motion disturbances can be recognized.
Other advantageous improvements of the invention are described in the dependent claims or, together with the following description of the prefered embodiment of the invention, are discussed in more detail using the figures. Shown are:
FIG. 1 a motion-analysis system according to the invention for the training of putting in golf,
FIG. 2 a position detector according to the invention that can be mounted on a golf club,
FIG. 3 an enlarged view from FIG. 1 with the position detector from FIG. 2 mounted on the golf club,
FIGS. 4 a to 4 e the method for motion analysis according to the invention in a flowchart,
FIGS. 5 and 6 different graphic renditions on the monitor that are generated within the framework of the method for motion analysis according to the invention, as well as
FIG. 7 an alternative embodiment of a motion-analysis system according to the invention.
FIG. 1 shows a golfer 1 putting with a golf club 2, wherein an active position detector 3, which is shown in detail in FIG. 2 and subsequently described, is detachably mounted on the shaft of the golf club 2.
The position detector 3 has two attachment screws 4, 5 with which the position detector 3 can be detachably mounted on the shaft of the golf club 2. The alignment of the position detector 3 in the rotation direction around the shaft of the golf club 2 is hereby accomplished by a gauge, which, for reasons of simplification, is not shown.
The position detector 3 essentially consists of a middle part 6, on whose free end an ultrasonic transmitter 7 is attached, wherein the middle part 7 branches out on the opposite end into two side arms 8.1, 8.2, on whose free ends another ultrasonic transmitter 9 or, respectively, 10, is attached in each instance.
The ultrasonic transmitters 7, 9, 10 are hereby arranged on a plane and emit in the same direction, wherein the individual ultrasonic transmitters 7, 9, 10 have, in each instance, a transmission angle of 180° and a maximum measurement distance of approximately 2 m and enable a measurement rate totaling 300 Hz.
On the top of the position detector 3, there is a connection to which a fourth sensor can be connected in order to separately measure wrist motions. The motions of the wrist are very important, especially when Yips problems are being measured.
Furthermore, the motion-analysis system can also process other measuring signals, if a position detector attached to the body of golfer 1 is used instead of position detector 3 on golfer 2. With such a position detector, other body movements, such as movements of the head, shoulders, back, and hips, can also be measured. In another embodiment of the invention, these body-specific signals can be simultaneously registered with a second measuring sensor that is connected to the same processor via a second control unit. The signals from the motion of the golf club 2 and the motion signals of the body can be analyzed and evaluated synchronously. With such a measuring unit, the connection between good performance during the short golf game and the associated body-specific movements can be measured for the first time. Furthermore the motion-analysis system can be operated in synchronization with other measuring systems, for example, for performing a synchronous determination of the ground reaction forces using a force-distribution measuring plate.
The position detector 3 is connected by a cable 11 to a control unit 12, which can have a conventional design. For the control unit 12, one can, for example, use the CMS10 or the CMS 20S measuring system, which is marketed by the aforementioned company zebras Medical GmbH.
The communication between the position detector 3 and the control unit 12, however, can alternatively be wireless, for example, it can be performed by an optical signal. In addition, a signaling transmitter (e.g., infrared), which, for example, is fastened to the belt of the golfer 1 and controls an additional receiver, can be controlled via a shortened cable. The measuring sensor is then preferably connected by a cable to the processor 19 via the control unit 12. The control unit 12 can hereby also be integrated with the measuring sensor 14 or combined with the processor 19.
Furthermore, the control unit 12 is connected by another cable 13 to an ultrasonic measuring sensor 14, which can be designed conventionally and is available, for example, together with the aforementioned measuring system of zebras Medical GmbH. The measuring sensor 14 is hereby arranged on a tripod and has three ultrasonic receivers 16, 17, 18, which are arranged on a single plane in the shape of a triangle and which are aligned, jointly and roughly parallel, to the position detector 3, in order to receive ultrasonic signals from the ultrasonic transmitters 7, 9, 10.
Via cable 11, the control unit 12 triggers the ultrasonic transmitters 7, 9, 10 to emit ultrasonic impulses that are recorded by the ultrasonic receivers 16-18 and transmitted via cable 13 to the control unit 12. The transit times of the ultrasonic impulses of the ultrasonic transmitters 7, 9, 10 until they are received by the ultrasonic receivers 16-18 are transmitted by the measuring sensor 14, via the cable 13, to the control unit 12 and, from there, via a data interface, to the processor 19. Using triangulation, the processor 19 calculates the positions of the individual ultrasonic transmitters 7, 9, 10 in three-dimensional space from the transit time of the ultrasonic impulses. From this raw data, the processor 19 then calculates the position data of the golf club 2 in real time by using coordinate transformation. The position data of the golf club 2 are analyzed in real time, and the results are alternately displayed on a monitor 20 and saved for further analysis in a measured value file. Operator prompting is hereby possible via an input device 21.
From the enlarged representation in FIG. 3, one can see that the position detector 3 is attached to the shaft of the golf club 2 in such a way that the ultrasonic transmitter 7 is located in the middle front of the shaft, while the side arms 8.1 and 8.2 stick out laterally from the shaft of the golf club 2. This arrangement of the position detector 3 enables a precise position determination using a triangulation of the ultrasonic impulses that are emitted by the three ultrasonic transmitters 7, 9, 10.
FIGS. 4 a to 4 e show the method of motion analysis according to the invention in a flowchart. In the segment of the method shown in FIG. 4 a, preliminary tasks, such as the mounting of the position detector 3 onto the golf club 2, as well as the set-up of the measuring sensor 14 with the tripod 15 and the alignment of the measuring sensor 14 in the direction of golfer 1, are initially performed.
Furthermore, the entire system is calibrated in this segment of the method, in order to enable a precise recording of the position. For this, the club head of the golf club 2 is calibrated, in the horizontal direction, precisely in the direction of the sighted target (“alignment”), and, in the vertical direction, the club head is calibrated in the direction of the the gradient opposite the verticals (“loft”).
In the segment of the method shown in FIG. 4 b, the actual measurement of the motion of golf club 2 is then performed, wherein this segment of the method is constantly repeated in the background during operation. During a measurement in the diagnosis mode, several swings are normally performed one after the other, in order to test the consistency of motion execution. Typically, there are five putts to the same goal.
During this procedure, the ultrasonic transmitters 7, 9, 10 of the position detector 3 constantly emit ultrasonic signals that are received by the ultrasonic receivers 16 to 18 of the measuring sensor 14.
The control unit 12 then measures the transit time of the ultrasonic signals between their emission by the ultrasonic transmitters 7, 9, 10 of the position detector 3 and their reception by the ultrasonic receivers 16 to 18 of the measuring sensor 14.
Finally, from the measured transit times, the processor 19 calculates the positions of the ultrasonic transmitters 7, 9, 10, and, from these positions, it calculates the position and alignment of the club head using coordinate transformation, wherein a defined alignment of the position detector 3 relative to the golf club 2 is taken as the basis.
In order to make an operator intervention superfluous for the measuring and storing of the data on individual swings, the swing motions within the continuous data stream are automatically identified according to precisely defined criteria, a task that is performed in the segment of the method shown in FIG. 4 c. For this, diverse criteria are combined in a combination of time sequences, motion direction, and motion dynamics. First, the golf club 2 must be kept still for a certain period of time (for example, for 1 second). Then the club must be moved away from the goal in the negative direction at a certain minimum velocity. Within a certain period of time, the backward motion must then be stopped and converted seamlessly into a forward motion. Within a certain period of time, a certain forward velocity must then be exceeded. Within a certain period of time, the swing velocity must then decrease to below a certain threshold value, in order to indicate the end of the stroke. If one of the specified conditions is not met, the measurement cycle is interrupted, and the motion is rejected as invalid.
If, on the other hand, a valid swing cycle was identified in the continuous data stream, then the associated position data and the alignment of the club head of golf club 2 are stored, along with the respective measurement times for the subsequent analysis of the swing motion.
If the swing motion did not end correctly, then the segment of the method shown in FIG. 4 c is repeated. If a swing is ended and the required number of strokes have not yet been completed, then the segment of the method shown in FIG. 4 c is performed again. Otherwise, one skips to the segment of the method shown in FIG. 4 d in which the actual analysis and display of the motion data is performed as described below.
In contrast to the diagnosis mode, in the training mode, only one motion is executed each time. This is immediately analyzed in real time, and the results displayed on the monitor. Thus, the golfer 1 can immediately see how close he or she has come to the standard for each stroke. In contrast to the continuous biofeedback, here a so-called kinetic feedback is used (“knowledge of result”). Continuous motion feedback, on the other hand, would disrupt motion execution; and it has proven to be unsuitable for the learning of automated movements.
Before the data can be evaluated, they undergo an error analysis and data filtering, which is shown in FIG. 4 d. Since all biomechanical signals entail a certain error ratio and this error ratio is multiplied when dynamic aspects, such as, velocity and acceleration, are calculated, then valid data filtering plays a decisive role. On the basis of scientific findings, a sliding average filter is used here that, as has been proven, produces the best filtering results for motion data. This filter is described, for example, in MARQUARDT, C. & Mai, N.: “A computational procedure for movement analysis in handwriting” (Journal of Neuroscience Methods, 52, 39-45); thus the entire contents of this publication should be included in the existing description, and a detailed description of the data filtering is not needed here.
Since the impact time of the golf club 2 on the golf ball cannot be measured acoustically due to the low velocity of the club, the moment of impact is calculated from the data stream. In order to determine the impact time, a combination of the position when the swing begins, the club height, and the measured impact impulse of the ball on the golf club 2 is used in the acceleration signal. An additional acceleration sensor mounted on the club can also be used to determine the impact time.
In order to calculate the different motion parameters, the data of the individually stored motions are automatically classified into seven (7) different motion segments, which include:

- 1) beginning of the backswing,
- 2) beginning of the follow-through,
- 3) maximum acceleration,
- 4) impact time
- 5) maximum velocity,
- 6) maximum braking,
- 7) end of the follow-through.

Based on the seven (7) motion segments, the twenty-eight (28) different motion parameters are then calculated, some of which are shown as examples in the monitor printouts in FIGS. 5 and 6. For example, within the framework of the motion analysis, the maximum velocity and the maximum acceleration of the club head of the golf club 2 are calculated in advance. All calculated data curves can be depicted graphically and, together with the associated motion parameters, combined with one another and displayed on the monitor or printed out in any manner whatsoever.
Finally, the motion parameters (e.g., maximum acceleration) that have been determined in this way are standardized into corresponding Z values using a transformation, wherein the combined Z values form a skills profile that is graphically depicted in FIG. 6.
Additionally, an overall performance index, which reflects the performance capability of the respective golfer 1, is calculated from the Z values.
Furthermore, a competency profile of a well-known golfer can be selected as a reference from a database that is stored in the processor 19 and then displayed graphically on the monitor. In FIG. 6, this competency profile serving as reference is always shown in the middle as a gray shaded field, while the actually determined Z values of the golfer 1 appear as black bars that lie partially outside of the range of the competency profile that serves as a reference.
Finally, the determined competency profile and the competency profile selected to serve as reference are graphically depicted, whereby the monitor printouts from FIGS. 5 and 6 are to be understood only as examples.
The embodiment of a motion-analysis system according to the invention, which is shown in FIG. 7, largely corresponds to the motion-analysis system that was previously described and depicted in FIG. 1, so that, in order to avoid repetition, reference is generally made to the aforementioned description; and the same indicators are used below for corresponding components.
In this embodiment, the determination of the position and alignment of the golf club 2 is based, however, on what is basically a technically different principle. Thus, the position detector 3 has several acceleration sensors that record the acceleration of the position detector 3, from which the control unit 12, in conjunction with the processor 19, can then calculate the position and alignment of the golf club 2.
The invention is not limited to the preferred aforementioned embodiment examples. Rather, a number of variants and adaptations are possible that also make use of the scope and nature of the invention and therefore lie within the range of protection.

Claims

1. Position detector (3) characterized by a mounting arrangement with which the position detector (3) can be detachably mounted on a ball sport device (2).

2. Position detector (3) according to claim 1, characterized in that the ball sport device (2) is a golf club.

3. Position detector (3) according to one of the preceding claims, characterized by at least one transmitter (7, 9, 10) for emitting a position signal to a stationary receiver (16-18), wherein the receiver (16-18) determines the position and/or the alignment of the ball sport device (2), dependent upon the received position signal.

4. Position detector (3) according to claim 3, characterized by at least three, interspaced transmitters (7, 9, 10), each of which emits a position signal to three stationary and interspaced receivers (16-18).

5. Position detector (3) according to claim 1 or 2, characterized by at least one receiver for receiving the position signal from a stationary transmitter, wherein the receiver determines the position and/or the alignment of the ball sport device, dependent upon the received position signal.

6. Position detector (3) according to claim 5, characterized by at least three, interspaced receivers, each of which receives a position signal from three stationary and interspaced transmitters.

7. Position detector (3) according to one of the claims 3 to 6, characterized in that the transmitter (7, 9, 10) is an ultrasonic transmitter.

8. Position detector (3) according to one of the claims 3 to 7, characterized in that the transmitters (7, 9, 10) are essentially arranged on one plane (flush).

9. Position detector (3) according to one of the claims 3 to 8, characterized in that the transmitters (7, 9, 10) essentially emit the position signals in the same direction.

10. Position detector (3) according to one of the claims 3 to 9, characterized in that the three transmitters (7, 9, 10) are essentially arranged in the shape of a triangle.

11. Position detector (3) according to one of the claims 3 to 10, characterized in that one of the transmitters (7, 9, 10) is arranged, in the mounted state, flush with the shaft of the ball sport device (2), while the two other transmitters (9, 10) are arranged on opposite sides of this plane.

12. Position detector (3) according to claim 1 or 2, characterized in that the position detector has at least one acceleration sensor.

13. Position detector (3) according to one of the claims 2 to 12, characterized in that the position detector (3) can be mounted on the shaft of the ball sport device (2).

14. Position detector (3) according to one of the preceding claims, characterized in that a cable connection (11) is provided for wire communication with a stationary control unit (12).

15. Position detector (3) according to one of the preceding claims, characterized in that an additional transmitter is provided for wire communication with a stationary control unit (12).

16. Position detector (3) according to claim 15, characterized in that the additional transmitter can be attached to the body of a golfer.

17. Motion-analysis system with a position detector (3) according to one of the preceding claims and a control unit (12) that is connected to the position detector (3) in order to control and assess the motion analysis.

18. Method of motion analysis, characterized in that the motion of the ball sport device (2) during a swing is recorded and analyzed by a position detector (3) mounted on the ball sport device (2).

19. Method of motion analysis according to claim 18, characterized in that the ball sport device (2) is a golf club.

20. Method of motion analysis according to one of the claims 18 to 19, characterized by the following steps:

transmission of a position signal between the position detector (3) mounted on the ball sport device (2) and a stationary control unit (12),

determination of the position and/or the alignment of the ball sport device (2), dependent upon the position signal.

21. Method of motion analysis according to claim 20, characterized in that the transit time of the position signal between the position detector (3) and the control unit (12) is measured, and then the position and/or alignment of the ball sport device (2) is determined using the transit time.

22. Method of motion analysis according to claim 20 or 21, characterized in that the position detector (3) and the control unit (12) have several interspaced transmitters (7, 9, 10) or several interspaced receivers, among which several position signals are transmitted, wherein the position and/or the alignment of the ball sport device (2) is determined, dependent upon the position signals.

23. Method of motion analysis according to one of the claims 18 to 22, characterized in that the following data are determined from the position and/or the alignment of the ball sport device (2):

start of a swing motion and/or

end of a swing motion and/or

moment of impact of the ball sport device (2) on the ball.

24. Method of motion analysis according to one of the preceding claims, characterized in that at least one of the following swing parameters is determined for a swing from the position and/or the alignment of the golf club (2):

duration of backswing

duration of follow-through

impact time

symmetry of the impact time

symmetry of the velocity profile

alignment when addressing the ball

club head at the moment of impact

differential value for alignment

rotation to the moment of impact

rotation after the moment of impact

rotation rate per time

horizontal angle of the club head on the swing path

loft of the club at the moment of impact

point of impact on the club head

height of club at moment of impact

length of backswing

length of follow-through

symmetry of swing path

horizontal direction of the swing path at the moment of impact

vertical incline of the swing path at the moment of impact

maximum backswing velocity

velocity at impact

maximum follow-through velocity

maximum acceleration

acceleration after impact

maximum braking

average jerk during the backswing

average jerk during the follow-through.

25. Method of motion analysis according to one of the claims 18 to 24, characterized in that the variability is calculated for each of the swing parameters in order to measure motion consistency.

26. Method of motion analysis according to one of the claims 18 to 25, characterized in that the swing parameters are graphically displayed.

27. Method of motion analysis according to one of the claims 18 to 26, characterized in that the chronological sequence of the swing parameters is graphically displayed.

28. Method of motion analysis according to one of the claims 24 to 27, characterized in that the swing parameters are normalized.

29. Method of motion analysis according to one of the claims 18 to 28, characterized in that the swing parameters are compared to stored reference values and/or displayed together with the reference values.

30. Method of motion analysis according to one of the claims 28 to 29, characterized in that an Overall-Performance-Index is calculated from the normalized swing parameters in order to determine the performance of the golfer.

31. Method of motion analysis according to one of the preceding claims, characterized in that, in addition to the position determination of the club, other position signals, such as, the positions and motions of the golfer's body, are synchronously recorded and jointly analyzed.

32. Method of motion analysis according to one of the preceding claims, characterized in that, in addition to the position determination of the club, the ground reaction forces during golf play are synchronously measured and analyzed using a force measuring plate.

33. Method of motion analysis according to one of the claims 18 to 32, characterized in that motion problems, such as the Yips Syndrome, can be classified and identified already before they actually occur by using the calculated competency profile.

34. Method of motion analysis according to one of the claims 18 to 33, characterized in that the position detector has at least one acceleration sensor that produces an acceleration signal corresponding to the motion of the ball sport device.

35. Method of motion analysis according to claim 34, characterized in that the position signal that is dependent upon the transit time is balanced with the acceleration signal, in order to increase the precision.

36. Method of motion analysis according to claim 34, characterized in that the position signals and the angle signals of the club are reconstructed from the acceleration signals, in order to calculate the swing parameters from them.