EP2852442A1

EP2852442A1 - Tennis racket

Info

Publication number: EP2852442A1
Application number: EP13725144.3A
Authority: EP
Inventors: Pierre Mace; Sébastien RICCARDI
Original assignee: Babolat VS SA; Movea SA
Current assignee: Babolat VS SA
Priority date: 2012-05-23
Filing date: 2013-05-23
Publication date: 2015-04-01
Anticipated expiration: 2033-05-23
Also published as: FR2990876A1; EP2852442B1; US20150157901A1; WO2013174922A1; FR2990876B1

Abstract

The invention relates to a tennis racket. Said tennis racket includes a head including a frame surrounding a netting of string, a holding handle (2), as well as a vibration sensor (14.1), a triaxial linear acceleration sensor (14.2), and a triaxial angular speed sensor (14.3).

Description

TENNIS RACKET

The present invention relates to a tennis racket.

When a player practices tennis, it is advantageous to be able to analyze his performances, for example in order to evaluate and / or improve his playing technique.

US-A-2006/0025229 discloses a system for measuring the movement of a tennis racket, comprising a two-axis linear acceleration sensor and a triaxial angular velocity sensor. This system does not allow for satisfactory measurements of the tennis racket movement.

The invention provides an improved tennis racket for measuring parameters for analyzing gestures and strokes of the player.

For this purpose, the invention relates to a racket which comprises:

a head comprising a frame surrounding a sieve,

- a grip handle,

a vibration sensor, a triaxial linear acceleration sensor and a triaxial angular velocity sensor.

Thanks to the invention, the measurements of vibration, angular velocity and linear acceleration make it possible to obtain measurements of parameters relating to the performance of the player. These parameters are recorded by the racket and can be transferred to an analysis station such as a computer, a graphics tablet or a smartphone that processes the data recorded by the racket. The racket according to the invention is light. In addition, it has a satisfactory autonomy and mechanical strength.

According to advantageous but non-mandatory aspects of the invention, such a racket may incorporate one or more of the following features, taken in any technically permissible combination:

- The tennis racket further comprises means for storing the data recorded by the sensors and means for transmitting the data recorded by the sensors, in particular wired connection means, preferably a USB type electrical connector, and / or wireless transmission means, preferably a Bluetooth type antenna.

- The vibration sensor is attached to the head of the racket, especially by gluing.

- The head comprises connecting branches that connect the screen to the handle and the vibration sensor is fixed on a connection area of the connecting branches.

- The triaxial linear acceleration sensor and the triaxial angular speed sensor are integral with the handle. - At least one electrical circuit associated with the sensors is attached to a removable housing which is removably attached to the frame of the racket.

- At least one of the sensors is also attached to the removable housing.

- The handle is hollow and encloses the removable housing.

- The electronic circuit is equipped with the triaxial linear acceleration sensor and the triaxial angular speed sensor and attached to the removable housing.

- The removable housing is attached to the frame of the racket by means of removable fasteners, such as screws.

- The fasteners are oriented perpendicular to the handle.

- The hollow body of the handle has two inner rails parallel to the handle and the removable housing has two longitudinal grooves.

- The tennis racket further comprises a heel fixed to the housing, at the free end of the handle, by means of removable fasteners oriented parallel to the handle.

- The tennis racket also includes a rechargeable battery that powers the electronic circuit.

- The racket further comprises a heel which is fixed to the housing at the free end of the handle, and which closes the handle tightly while allowing the manipulation of control buttons of the electronic circuit.

- The vibration sensor is stuck on the frame of the racket and is connected, by means of electrical son or an electrical contact provided on the removable housing, to an electronic circuit fixed to the removable housing.

The invention will be better understood and other advantages thereof will appear more clearly in the light of the following description of two embodiments of a racket according to the invention, given solely by way of example and with reference to the accompanying drawings in which:

- Figure 1 is a front view of a racket according to the invention;

- Figure 2 is a partial exploded view and in perspective of the racket of Figure 1;

FIG. 3 is a view, on a larger scale, of detail III in FIG. 2;

- Figure 4 is a partial exploded view in perspective of the handle of a racket according to a second embodiment of the invention;

- Figure 5 is an exploded perspective view, on a larger scale, of the handle of Figure 4, being mounted;

- Figure 6 is a view along the arrow F6 in Figure 5; and - Figure 7 is a view similar to Figure 6, in the assembled configuration of the handle.

Figures 1 to 3 show a tennis racket 1, which comprises in a conventional manner a handle 2 connected to a head T including a frame 4 inside which is stretched a sieve not shown, formed of different transverse and longitudinal strings. The head T also comprises two connecting branches 6 extending divergently from the handle 2 to the frame 4. At a connection zone R of the head T with the handle 2, the connecting branches 6 are integral. one from the other.

The handle 2 comprises a hollow body 21 and generally tubular, made for example of carbon. Conventionally, the body 21 is covered with a thickness of foam surrounded by a grip, to improve grip of the handle. The body 21 of the handle 2 has a proximal longitudinal end 21 .1, located on the sieve side and connected to the connecting branches 6, and a distal longitudinal end 21 .2, free and opposite the end 21 .1. The end 21 .2 is covered by a heel 22, generally designated by the term "butt cap" in English, which allows the player's hand not to slip off the handle 2. The heel 22 comprises a body 221 covered by a cover 223 assembled with the body 221 by snapping. Thus, the user can easily remove the cover 223, without the aid of tools. In addition, flexible fastening elements, not shown, connect the cover 223 to the body 221, to avoid disengaging the cover 223 from the racket 1 when using the racket 1.

The racket 1 is equipped with a game parameter measuring system, comprising a vibration sensor 14.1 which is fixed on the connecting branches 6, at the connection zone R, in particular by gluing. The vibration sensor 14.1 is for example a piezoelectric sensor, which measures the deformations generated by the vibrations of the racket 1. As a variant, it may be an accelerometer calibrated on vibration frequencies, in particular from 100 Hz to 600 Hz.

The vibration sensor 14.1 is covered by an end portion 23 of the body 21 of the handle 2, surrounded by an attached ring 24, generally designated by the term "front cap" in English.

The vibration sensor 14.1 is connected to an electronic circuit 20, by means of unrepresented electrical wires housed in the body 21 of the handle 2. The electronic circuit 20 is mounted on plates fixed in a plastic housing 16, which is housed inside the body 21, on the side of the free end 21 .2 of the body 21. The housing 16 comprises a body 16.1 and a lid 16.2 of elongate shape. The cross-section of the body 16.1 is generally shaped "U" and the cover 16.2 closes the open side of the body 16.1. Screws are used to secure the lid 16.2 to the body 16.1.

Alternatively, the electrical wires are replaced by an electrical contact provided on the housing 16 and which receives in contact the vibration sensor 14.1 when the housing 16 is inserted into the handle 2.

On the side of the free end 21 .2 of the handle 2, the body 16.1 of the housing 16 comprises a transverse plate 16.4 perpendicular to the handle 2, whose geometry is substantially identical to the section of the body 21 of the handle 2. The electronic circuit 20 is mounted on a longitudinal plate 20.1 disposed in the volume of the housing 16, as well as on a transverse plate 20.2 fixed outside the housing 16, on the transverse plate 16.4 of the housing 16, and perpendicular to the plate 20.1.

The transverse plate 16.4 of the housing 16 has an opening 16.6 provided for the insertion of the longitudinal plate 20.1 of the electronic circuit 20 into the housing 16, for mounting the electronic circuit 20 in the housing 16.

A rechargeable electric battery 18 is connected to the cover 16.2 of the housing 16, snap-fastening, and supplies the electronic circuit 20 via unrepresented electrical wires.

The longitudinal plate 20.1 of the electronic circuit 20 carries a triaxial linear acceleration sensor 14.2, which measures the acceleration of the racket 1, as well as a triaxial angular velocity sensor 14.3, which measures the rotational speed of the racket 1. The sensors 14.2 and 14.3 measure the acceleration and the angular velocity in three directions X, Y and Z perpendicular to each other, fixed with respect to the terrestrial reference system.

The sensors 14.1 and 14.2 are fixed to the housing 16 because they are fixed to the electronic circuit 20, the electronic circuit 20 being fixed to the housing 16. In a variant, the sensors 14.1 and 14.2 are fixed on the racket 1, whereas the circuit 20 is attached to the housing 16.

The electronic circuit 20 comprises a memory, not shown, which records the measurements of the sensors 14.1, 14.2 and 14.3.

The transverse plate 20.2 carries three control buttons 15.1, 15.2 and 15.3, allowing the user to control the system for measuring the game parameters, as well as diodes 13 which light up with different colors depending on the actions of the game. on the control buttons 15.1, 15.2 and 15.3.

The longitudinal plate 20.1 carries wireless communication means, formed by a Bluetooth antenna 1 1 able to transmit and receive data by air. In addition, the longitudinal plate 20.1 is electrically connected to a connector female USB type electrical 17, which passes through the transverse plate 20.2 and which is intended to connect the racket 1 to an analysis station by a wired connection. In order to save space, the connector 17 is optionally of the mini-USB or micro-USB type. Thus, the racket 1 is able to communicate by wire or air with a computer, a smart mobile phone or a graphics tablet.

The transverse plate 20.2 is covered by a flexible element 5 having openings 51 and 52 disposed at the connector 17 and diodes 13, to allow access to the connector 17 and the visibility of the diodes 13, as well as the reliefs 53.1 and 53.2 arranged at the control buttons 15.1 and 15.2 provided to improve the manipulation of the buttons 15.

On the side of the end 21.2, four metal plates 19 are fixed to the body 21 of the handle 2.

The assembly of the various components of the handle 2 is achieved by inserting the plates 19 in the flat housing 21 .3. Then, the housing 16 is inserted into the inner volume of the body 21 of the handle 2, the side of the free end 21 .2. The transverse plate 16.4 of the housing 16 then abuts against the free end 21 .2 of the handle 2.

The housing 16 is fixed to the frame 4 of the racket 1 removably. In other words, the housing 16 is removable. More specifically, the housing 16 is removably attached to the handle 2. Four transverse screws 3 oriented perpendicularly to the handle 2 are used to secure the plates 19 and the housing 16 to the body 21 of the handle 2. The screws 3 are inserted into holes 21 .4 made in the body 21 of the handle 2, at the free end 21 .2. The screws 3 pass through holes 19.1 formed in each plate 19 and engage with holes in the housing 16. The plates 19 make it possible to improve the anchoring of the screws 3 in the body 21 of the handle 2, since the walls of the body 21 are relatively thin.

The screws 3 constitute removable fastening means for fixing the casing 16 to the frame 4 of the racket 1. Alternatively, other removable attachment means may be used.

Thus, it is possible to disassemble the casing 16 without damaging the racket 1, which makes it easier to maintain the casing 16. Moreover, the casing 16 being removable, this makes it possible to recycle the various components of the racket 1. In addition, this makes it possible to manufacture several identical housings 16 and to mount them in different rackets, which is economical. The electronic circuit 20 is assembled to the housing 16 by sliding the longitudinal plate 20.1 in the opening 16.6 of the housing 16. The transverse plate 20.2 of the electronic circuit 20 then abuts against the transverse plate 16.4 of the housing 16. The flexible element 5 is disposed against the transverse plate 20.2 of the electronic circuit, and the body 221 of the heel 22 is inserted around the free end 21 .2 of the body 21 of the handle 2.

Four longitudinal screws 7, oriented parallel to the handle 2, are used to fix the heel 22 to the housing 16. The longitudinal screws 7 each pass successively in a hole 222 formed in the body 221 of the heel 22, in a hole 53 of the element 5, in a hole 20.3 of the transverse plate 20.2 of the electronic circuit 20 and in a threaded hole 16.5 of the transverse plate 16.4 of the housing 16. Thus, the heel 22 is secured to the housing 16 and the electronic circuit 20 is held between the heel 22 and the housing 16. The heel 22 is thus integral with the body 21 of the handle 2, through the housing 16.

After the introduction of the four longitudinal screws 7, the cover 223 of the heel

22 is attached to the body 221 of the heel 22. The materials of the cover 223 and the part 5 allow the light of the diode 13 to be visible from the outside. To connect a cable to the electrical connector 17, the user removes the cover 223 from the heel 22.

In a conventional manner, weights can be fixed to the casing 16, for the balancing of the racket 1.

The antenna 1 1 is outside the body 21 of the handle 2, which allows it to send and receive signals without the material of the body 21 is a barrier.

The racket 1 has a reduced mass and a good mechanical resistance. In addition, the handle 2 is waterproof.

The remainder of the description relates to a method for measuring and calculating game parameters using the racket 1.

In a previous step a), behavioral data of the racket 1 are generated during tests, by measuring the vibrations, the linear acceleration and the angular speed of the racket, by means of the sensors 14.1, 14.2 and 14.3, for various parameters strikes the player, when he realizes specific types of shots (forehand shot, service, backhand cut ...).

Each keystroke is characterized by several parameters. For example, a first parameter is the type of shot (forehand, backhand or service), determined according to the linear acceleration of the racket 1 and its angular velocities. A second parameter is the type and amount of effect (lift, slice, or flat blow) determined by the ratio of the angular velocity of the upward movement to the advance movement of the racket 1 just before the strike.

A third parameter is the striking power, determined at the moment of striking, as a function of the linear acceleration and the angular velocities of the racket 1.

A fourth parameter is the location of the impact zone of the bale on the sieve 8, determined according to the measurements of the three sensors 14.1, 14.2, 14.3. The screen 8 can be divided into several areas shown in Figure 1: a central zone M1, generally circular, and four peripheral zones M2, M3, M4 and M5 which divide the remaining portion of the sieve 8 into four quarters: a front quarter M2 located between the central zone M1 and the end of the frame 4 opposite the handle 2, a rear quarter M4 located between the central zone M1 and the part of the frame 4 connected to the connecting branches 6, and two lateral quarters M3 and M4 located either side of the central area M1, between the front quarters M2 and rear M4. Alternatively, the division of the zones and the number of zones may be different.

The behavioral data are stored in a memory of the analysis station and indicate, for each parameter, the vibrations, the linear acceleration and the angular velocity of the racket 1.

In an initialization step b), the player turns on the racket 1 and starts the recording of the game data, using the button 15.1.

Then, in a game stage c), the player strikes balls, while the sensors 14.1, 14.2 and 14.3 record in the circuit memory 20 game data relating to vibration, angular velocity and linear acceleration racket 1.

In a transmission step d), occurring after or during the game step b), the game data is transmitted to an analysis station, by wire, using the connector 17, or by air, in using the antenna 1 1. For example, the wired connection can be used at the end of the game and the airway can be used in real time, during the game, to communicate the data to a trainer.

Finally, in an analysis step e), the analysis station compares the game data and the behavioral data of the racket 1 and determines, from this comparison, at least one parameter characterizing the player's gestures and strikes. . For example, the analysis station deduces at least one of the game parameters described above. It is thus possible to know if the player has made a forehand, a backhand or a service, if he has put the effect and to what extent, the power of the shot and the zone of impact of the ball on the sieve 4. Figures 4 to 7 show a racket sleeve 102 according to a second embodiment of the invention, the elements similar to those of the racket 1 have the same reference numerals. In the following, we do not describe the elements similar to those of racket 1.

The handle 102 comprises a hollow body 21, which has two inner rails 31 and 32 parallel to the handle 102.

The handle 102 comprises a housing 16 of elongated shape, rectangular section, in which is fixed an electronic circuit not shown. The housing 16 has two longitudinal grooves 41 and 42.

Note d1, the distance between the rails 31 and 32 of the handle 2 and h1, the height of the section of the internal volume of the body 21 of the handle 2, measured perpendicular to the distance d1. The distance d1 is less than the height h1. The rails 31 and 32 extend along a plane P1.

Note d2, the distance between the bottom of the grooves 41 and 42 of the housing 16 and h2 the height of the section of the housing 16, measured perpendicular to the distance d2. The distance d2 is greater than the height h2. The grooves 41 and 42 extend along a plane P2.

The distance h2 is slightly less than the distance d1. The distances d1 and d2 are equal to the operating clearances.

To assemble the housing to the body 21 of the handle 102, the housing 16 is inserted into the volume of the body 21 of the handle 2, by orienting the plane P1 perpendicular to the plane P2, as shown in Figures 5 and 6.

The housing 16 is pressed into the body 21 of the handle 102 until it completely extends beyond the end of the rails 31 and 32 opposite the free end 21 .2 of the body 21.

Then, the housing 16 is rotated a quarter turn around the longitudinal axis of the housing 16, which is aligned with the direction of the body 21 of the handle 102. The planes P1 and P2 are then aligned.

Then, as shown in Figure 7, the housing 16 is translated to the free end 21 .2 of the handle 2, so as to slide the rails 31 and 32 of the handle 2 in the grooves 41 and 42 of the housing.

The housing 16 is then locked in rotation about its longitudinal axis by the rails 31 and 32 of the body 21 of the handle 21. A heel 22 is fixed to the body 21 of the handle 2, by means of screws not shown, to block the translation of the housing 16 relative to the body 21, along the longitudinal axis of the housing 16 and in a direction opposite to the head of the racket.

The housing 16 is fixed to the frame 4 of the racket 1 removably. In other words, the housing 16 is removable. More specifically, the housing 16 is removably attached to the handle 2.

The screws used to attach the heel 22 to the body 21, associated with the rails 31 and 32 which cooperate with the grooves 41 and 42, constitute removable fixing means for fixing the housing 16 to the frame 4 of the racket 1.

When the cover 223 of the heel 22 covers the body 221, the heel 22 seals the sleeves 2 and 102, on the side of the free end 21 .2, which protects the electronic circuit 20 from rain or perspiration. of the player. In addition, the cover 223 of the heel 22 allows the player, when the cover 223 covers the body 221, to use the buttons 15.1 and 15.2. Indeed, the cover 223 is made of a material that has a flexibility allowing the player, when pressing the cover 223, to deform it to actuate the buttons 15.1 and 15.2. In this way, it can activate or deactivate the measurement system during the game and enable or disable the data exchange via the antenna 1 1. Button 15.2 also allows to split the recording into several game sequences: when the measuring system is active and each time the player presses this button 15.2, a time marker is created, in order to separate the recorded data into several This function allows you to analyze the game according to the chosen sequence.

The button 15.3 is not accessible when the cover 223 of the heel 22 covers the body 221. This button 15.3 resets the measurement system. To actuate it, it is necessary to remove the cover 223 and to press on the part 5 which deforms and comes into contact with the button 15.3. In this configuration, it is also possible to access the connector 17.

In the examples described, two sensors are attached to the housing 16, namely the sensors 14.2 and 14.3. Alternatively, a single sensor is attached to the housing 16, namely the sensor 14.1, 14.2 or 14.3. In another variant, the three sensors 14.1, 14.2 and 14.3 are fixed to the housing 16. Thus, at least one of the sensors 14.1, 14.2 and 14.3 is fixed to the housing 16.

Claims

1. - Tennis racket (1), including:

- a head (T) comprising a frame (4) surrounding a sieve, and

- a gripping handle (2),

characterized in that it further comprises a vibration sensor (14.1), a triaxial linear acceleration sensor (14.2) and a triaxial angular velocity sensor (14.3).

2. - Tennis racket (1) according to claim 1, characterized in that it further comprises means for storing data recorded by the sensors

(14.1, 14.2, 14.3) and means (1 1, 17) for transmitting the data recorded by the sensors (14.1, 14.2, 14.3), in particular wired connection means (17), preferably a USB type electrical connector , and/or wireless transmission means (1 1), preferably a Bluetooth type antenna.

3. - Tennis racket (1) according to one of the preceding claims, characterized in that the vibration sensor (14.1) is fixed to the head (T) of the racket (1), in particular by gluing.

4.- Tennis racket (1) according to one of the preceding claims, characterized in that the head (T) comprises connecting branches (6) which connect the sieve to the handle (2) and in that the sensor of vibrations (14.1) is fixed on a connection zone (R) of the connecting branches (6).

5.- Tennis racket (1) according to one of the preceding claims, characterized in that the triaxial linear acceleration sensor (14.2) and the triaxial angular speed sensor (14.3) are integral with the handle (2).

6. - Tennis racket (1) according to one of the preceding claims, characterized in that at least one electronic circuit (20) associated with the sensors (14.1,

14.2, 14.3) is attached to a removable housing (16) which is removably attached to the frame (4) of the racket (1).

7. - Tennis racket according to claim 6, characterized in that at least one of the sensors (14.1, 14.2, 14.3) is also fixed to the removable housing (16)

8.- Tennis racket (1) according to one of claims 6 or 7, characterized in that the handle (2) is hollow and encloses the removable housing (16).

9.- Tennis racket (1) according to one of claims 6 to 8, characterized in that the electronic circuit (20) is equipped with the triaxial linear acceleration sensor (14.2) and the triaxial angular speed sensor (14.3 ) and fixed to the removable housing (16).

10. - Tennis racket (1) according to one of claims 6 to 9, characterized in that the removable housing (16) is fixed to the frame (4) of the racket (1) by means of fixing elements ( 3) removable, such as screws.

1 1 . - Tennis racket (1) according to claims 6 and 10, characterized in that the fixing elements (3) are oriented perpendicular to the handle (2).

12. - Tennis racket (1) according to claims 6 and 8, characterized in that the hollow body (21) of the handle (2) comprises two interior rails (31, 32) parallel to the handle (2) and in that the removable housing (16) has two longitudinal grooves (41, 42).

13. - Tennis racket (1) according to one of claims 6 to 12, characterized in that it further comprises a heel (22) fixed to the housing (16), at the level of the free end (21. 2) of the handle (2), by means of removable fixing elements (7) oriented parallel to the handle (2).

14. - Tennis racket (1) according to one of claims 6 to 13, characterized in that it further comprises a rechargeable battery (18) which powers the electronic circuit (20). 15.- Tennis racket (1) according to one of claims 6 to 14, characterized in that it further comprises a heel (22) which is fixed to the housing (16), at the level of the free end ( 21.2) of the handle (2), and which seals the handle (2) while allowing the manipulation of buttons (15.1,

15.2) for controlling the electronic circuit (20).

16.- Tennis racket (1) according to one of claims 6 to 15, characterized in that the vibration sensor (14.1) is glued to the frame (4) of the racket (1) and is connected, by means of electric wires, to an electronic circuit (20) fixed to the removable housing (16).