Abstract:
A training device for rugby players, notably for a phase of the game known as the scrum, comprises: a simulation platform of the Stewart platform type, onto which a training yoke is mounted; an electronic device for closed-loop control of said simulation platform; a computer device for controlling the training device. The present invention is mainly applicable to the training, the development and the improvement of rugby players at a high level.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a National Stage of International patent application PCT/EP2011/051868, filed on Feb. 9, 2011, which claims priority to foreign French patent application No. FR 1000524, filed on Feb. 9, 2010, the disclosures of which are incorporated by reference in their entirety. 
     FIELD OF THE INVENTION 
     The present invention relates to a device for reproducing forces with six degrees of freedom, applied to the training of rugby players, notably during a phase of the game known as the ‘scrum’. The present invention is mainly applicable to the development, the training, and the improvement of rugby players of all levels. 
     BACKGROUND 
     In a Game of Rugby, One of the Phases of the Game that is particularly dangerous is the scrum. This phase of the game demands a high individual and collective technical expertise, together with an excellent physical condition for the scrum participants. Indeed, the injuries occurring during this phase of the game can be very serious, in particular for the right prop and the hooker owing to the forces that come into play and to their position in the scrum. 
     In the practice of rugby, in order to train technically and physically for the scrum, the players have static equipment available comprising for example a head yoke, for three people, allowing a first row of opponents to be simulated notably by its function as an end stop. However, this equipment does not allow the players to be prepared to undergo strong displacement forces such as those developed for example during a non-regulation forward push of the opposing pack, when a scrum collapses. Moreover, these types of equipment are not active and can only reproduce, at the most, the energy supplied and stored by the players. 
     This type of missing aspect in the training of a player makes him all the more vulnerable during matches given that he must handle unusual forces that are not reproduced in training for fear of injuries. 
     Amongst the existing training systems, a first device is described in the patent application FR2892941. The first device is a training apparatus for rugby players that can perform a measurement of forces produced by said rugby players. The first device comprises a scrum yoke, mounted onto a base unit resting on the ground. The base unit and the yoke can effect a translation under the effect of the thrusting of the players on the yoke. In addition, the yoke is mounted so as to be mobile on the base unit in order to have a degree of freedom in rotation about a substantially vertical axis. 
     A second device described in the patent application FR 2861313 describes an apparatus designed for the muscular or technical preparation of an individual. The second device comprises a machine designed to be set on the ground, support means against which the two shoulders of the person under training can rest and linking means between the support means and the machine, said linking means allowing a translational movement along a substantially horizontal axis of the support means with respect to the machine. In addition, the linking means allow a degree of rotation for the support means about a substantially horizontal axis. 
     The existing training systems can only therefore produce two degrees of freedom, one degree in translation and one degree in rotation about a vertical axis. These devices are therefore not very well adapted to a precise and tactical training such as is demanded by the high level of the current game of rugby. 
     Moreover, the existing systems have jerky and abrupt movements that can even be dangerous for the players, due to the use of pneumatic actuators or tensioning systems. Moreover, some of these systems, only used in laboratories, do not correspond to the CE directives on safety, CE being a French acronym for “Conformité Européenne” [European Conformity]. 
     SUMMARY OF THE INVENTION 
     One aim of the invention is notably to overcome the aforementioned drawbacks. For this purpose, the subject of the invention is a training device for rugby players. Said device notably comprises:
         a simulation platform, for example of the Stewart platform type, onto which a training yoke can be mounted;   an electronic device for closed-loop control of said simulation platform;   a digital device for controlling the training device.       

     The training yoke notably comprises yoke heads. Each yoke head can be connected to the simulation platform via a force sensor. The force sensors can supply measurements used for the closed-loop control of said simulation platform. 
     The measurements are notably transmitted to the computer control device for archiving and presentation to a coach for the players. 
     The computer device can supply means for programming training sequences comprising a series of commands for displacements of the platform. The series of commands can be transmitted to the electronic device for closed-loop control in order to mobilize the simulation platform. 
     The force sensors can measure forces and moments applied by the players to the yoke heads. 
     The computer device can comprise a device for driving the simulation platform in real time, said driving device being actuated by the coach. 
     The main advantages of the invention are notably that it allows:
         a manual control or an automatic control, by programming scenarios for the training device;   safe and reliable movements, closed-loop controlled to the force on the yoke;   measurements of forces and of moments produced by each yoke head;   a recording of the measurements and their presentation in an ergonomic manner;   a reproduction of forces exerted during a scrum by the opposing forwards.       

    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other features and advantages of the invention will become apparent by means of the description that follows, presented by way of non-limiting illustration and with reference to the appended drawings which show: 
         FIG. 1   a : a first view of the simulation platform of the device according to the invention; 
         FIG. 1   b : a second view of the simulation platform of the device according to the invention; 
         FIG. 2 : the training device according to the invention; 
         FIG. 3 : the degrees of freedom of the yoke of the simulation platform according to the invention. 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 1   a  and  1   b  Show Two Different Views of a Simulation platform  1  according to the invention. The simulation platform  1  according to the invention is a device designed for the training of rugby players, notably used for training of the players for a scrum situation with an opposing team. Advantageously, the simulation platform  1  replaces the opposing team during the training. The simulation platform  1  produces a movement along six axes, adapted to the mobilization of a yoke  2  according to six degrees of freedom: three degrees of freedom in translation, and three degrees of freedom in rotation. Such a simulation platform is known by the name ‘Stewart platform’, or alternatively ‘hexapod’. Advantageously, the use of a Stewart platform in the simulation platform  1  according to the invention accords it a high stability, and enables quick and accurate movements of the simulation platform  1 . 
     The simulation platform  1  comprises six axes  3 ,  4 ,  5 ,  6 ,  7 ,  8 . Each axis  3 ,  4 ,  5 ,  6 ,  7 ,  8  comprises an actuator which can take the form of an electrical linear drive. Each electrical linear drive can be actuated by a ‘brushless’ motor that advantageously runs with little noise. The simulation platform also comprises a pallet  9  composed of a metal plate. The pallet  9 , shown in  FIGS. 1   a  and  1   b , can take the form of a polygon, each polygon being formed by metal side-members. The axes  3 ,  4 ,  5 ,  6 ,  7 ,  8  are connected in pairs by means of three first articulations, on the one hand, to the pallet  9  and, on the other, to a base unit  10 . In  FIGS. 1   a  and  1   b , the base unit  10  is represented by three angle rails  10  onto which the axes  3 ,  4 ,  5 ,  6 ,  7 ,  8  are fixed by means of second articulations. Other embodiments of the base unit  10  may of course be envisioned, such as a single-piece metal plate. The angle rails  10  can be fixed onto a slab of a building for example. The yoke  2  comprises three yoke heads  11 ,  12 ,  13 . Each yoke head  11 ,  12 ,  13  is mounted onto the pallet  9  via a force sensor  14 ,  15 ,  16 . The yoke heads allow the three players of the first row to position their heads and shoulders in the yoke in order to apply a pushing force. The force sensors are notably used to measure the force applied by the three players of the first row of the scrum pack on the yoke  2 . Conventionally, a pack comprises eight players distributed as three players on a first row, four players on a second row and one player on the last row. The force sensors also allow the closed-loop control of the actuators for moving the six axes  3 ,  4 ,  5 ,  6 ,  7 ,  8 , as explained hereinafter. Placing the force sensors  14 ,  15 ,  16  as close as possible to the heads of the players with rigid yoke heads allows the training device to ensure the safety of the players using the device by, for example, imposing limits on the forces applied on the players. The rigidity of the heads allows the time delay between the forces actually applied on the player and the measurement of his effort exerted to be minimized. 
     Advantageously the use of such a platform according to the invention in the training device allows a robust and reliable training device to be made available. Indeed, the use of this type of platform  1  has been approved for many years in devices for the training of helicopter and aircraft pilots. 
       FIG. 2  shows the yoke  2  of the training device  1  according to the invention. In  FIG. 2 , the various possible movements of the yoke  2  are shown, according to various degrees of freedom, during the operation of the simulation platform according to the invention  1 . A first degree of freedom in translation is provided along a first axis  20  substantially perpendicular to the pallet  9 . A first degree of freedom in rotation is notably provided by a first rotation  21  about the first axis  20 . A second degree of freedom in translation is notably provided, by the platform  1 , along a second axis  22  substantially perpendicular to the first axis  20  and co-linear with a straight line passing through a central axis of a motion sensor  14 ,  15 ,  16 . A second degree of freedom in rotation  23  is provided by the platform  1  about the second axis  22 . A third degree of freedom in translation  24  is provided by the platform  1 , along a third axis  24  substantially perpendicular to the first axis  20  and to the second axis  22 . A third degree of freedom in rotation is provided about the third axis  24 . 
       FIG. 3  shows schematically one example of an architecture  30  of the training device according to the invention. The architecture  30  shown in  FIG. 3  comprises three separate parts  31 ,  32 ,  33 . 
     A first part  31  is a mechanical part comprising the simulation platform  1  according to the invention. 
     A second part  32  of the device according to the invention is an electronic part  32 . The electronic part  32  notably comprises six vari-speed drives  34 . Each vari-speed drive  34  is connected to an actuator for an axis  3 ,  4 ,  5 ,  6 ,  7 ,  8  shown in  FIGS. 1   a  and  1   b . The vari-speed drives  34  control the speed of the motors of each actuator. The power regulators are connected to three electronic boards  35 ,  36 ,  37 . The electronic boards  35 ,  36 ,  37  send commands to a closed-loop control for the actuators, in other words for their extension and their speed. The electronic boards  35 ,  36 ,  37  also acquire the information coming from the force sensors  14 ,  15 ,  16 . The information coming from the force sensors, in other words the forces applied on the heads of the players, is amplified by the electronic boards prior to being transmitted to a computer  38 . The electronic part also comprises an electrical power supply  39  for powering the electronic boards  35 ,  36 ,  37  and the vari-speed drives  34  with suitable voltages and currents. 
     A third part  33  of the device  30  according to the invention is a digital part  33 . A computer  38  allows the measurements from the force sensors  14 ,  15 ,  16  to be stored in a database. The measurements can thus be analyzed by a coach following a training session for example. The measurements, in other words the forces and the moments exerted by the players, can also be displayed in real time on a dedicated man-machine interface running on the computer  38 . The computer  38  can also comprise a software package for controlling the simulation platform  1 . The control software allows the simulation platform  1  to be controlled in all its degrees of freedom, with a response analogous to that of a scrum pack of opponents. The control software may itself be controlled via a man-machine interface allowing training sequences to be pre-programmed. For example, it is possible to simulate automatically either simple movements of the scrum, such as a rotation or a translation, or combinations of movements of rotation and translation. The control software can also be driven in real time by a coach by means of a ‘joystick’  300  for example. 
     Advantageously, it is thus possible to set up the training device for a reduced-power operation with the aim of teaching tactical skills and/or an understanding of risky situations. 
     The device according to the invention may also use a theoretical modeling of a scrum composed of opposing players, for which are notably available an estimation or measurements: of geometrical parameters, of parameters on inertia, of power characteristics, in order to produce training phases. 
     Another possible application of the device according to the invention is to connect remotely two devices according to the invention situated in two separate places and training two different teams in real time. The first device records the forces and the moments applied by the players of the first team on the first device. The first device transmits the measurements to the second device which, depending on these measurements, re-transmits the forces and the moments to the second team by means of the second device. It is also possible, for example, for two teams of different levels to apply a reducer coefficient to the forces and the moments applied by the second device. Advantageously, the system according to the invention can then allows two teams of the same level or of different levels to train remotely from one another and together. The device according to the invention then acts as a force transformer between the two scrum packs. 
     The device according to the invention allows the movements of a scrum composed of opposing players to be reproduced in order to establish training scenarios. The training scenarios can be generated by, for example, programming specific tactical scenarios, or a specific configuration for preparation of a match. 
     Advantageously, said device can be used over a network in order to undertake a remote training for two teams, said devices reproducing the efforts exerted by each of the teams against the opposing team. 
     The device according to the invention advantageously allows an ergonomic and dynamic yoke to be provided for a row of forwards in a rugby team, notably comprising a right prop, a hooker and a left prop. In addition, the device according to the invention allows forces, speeds and movements to be reproduced according to six degrees of freedom as in a real scrum.