EP2771079B1 - Exercise device - Google Patents

Description

The invention relates to the field of exercise machines. More particularly, the invention relates to the field of electrically powered machines designed to develop or reconstruct the musculature of a user and in particular for sports training or rehabilitation of the muscles of a user.

Muscular exercise machines include weight machines and inertia machines.

The weight machines operate on the principle of cast iron masses or other material that a user moves by providing an effort to counter the weight of the cast iron masses. These machines include presses, free bars, guided load devices etc.

Inertia machines work differently. These consist, for example, in setting a cast iron disk in motion about an axis of rotation. The user must therefore provide an adequate effort to overcome the inertia of the machine. Some machines work with the principle of moving a fluid with a fin system. Although the fluid in motion has an inertia, in these machines the user must overcome mainly the viscous friction induced by the fluids. Other machines use the principle of the eddy current system to generate these viscous friction. These machines producing viscous friction include rowing machines or indoor cycling.

The document WO2011 / 093434 discloses an exercise device as described in the preamble of claim 1.

According to one embodiment, the invention provides an exercise device comprising
a biasing element intended to be moved by the force of a user,
an electric actuator comprising a movable part, the biasing element being connected to the movable part and the biasing element being able to move the movable part,
a computer adapted to generate a control signal of the electric actuator and
an acceleration sensor coupled to the moving part for measuring the acceleration of the moving part and for transmitting the measured acceleration to the computer,
the electric actuator being adapted to exert a force on the biasing element via the moving part in response to the control signal,
in which the computer is able to generate the control signal as a function of the acceleration measured so that the force exerted by the electric actuator comprises an artificial inertia contribution substantially proportional to the acceleration measured by the acceleration sensor.

According to one embodiment, the computer is able to generate the control signal as a function of the measured acceleration and a coefficient of proportionality and the computer is able to vary the coefficient of proportionality as a function of at least one parameter chosen from position, speed and acceleration of the moving part.

According to one embodiment, the computer is able to generate the control signal so that the force exerted by the electric actuator comprises an additional load contribution having a predetermined direction.

According to one embodiment, the computer is able to generate the control signal so that the artificial inertia contribution is oriented in the same direction as the predetermined direction contribution when the measured acceleration is in the opposite direction of the contribution. predetermined meaning.

According to one embodiment, the computer is able to generate the control signal so as to cancel the artificial inertia contribution when the measured acceleration is in the same direction as the predetermined direction contribution of the electric actuator.

According to one embodiment, the connection between the biasing element and the mobile part comprises a speed reducer to increase the force of the motor. Generally, such a reducer generates additional real inertia for the user who actuates the biasing element. According to one embodiment, the artificial inertia contribution exerted by the electric actuator can compensate all or part of the additional real inertia generated by the gearbox.

According to one embodiment, the device comprises a speed sensor capable of measuring the speed of the moving part and the computer is able to generate the control signal so that the force exerted by the electric actuator comprises a viscous friction contribution. substantially proportional to the speed measured by the speed sensor.

According to one embodiment, the electric actuator is a linear motor.

According to one embodiment, the electric actuator is a rotary motor in which the movable portion comprises a rotor of the rotary motor.

• un codeur de position couplé à la partie mobile pour mesurer la position de la partie mobile, le codeur de position générant un signal de position,
• des éléments de dérivation aptes à dériver le signal de position pour déterminer l'accélération de la partie mobile.

According to one embodiment, the acceleration sensor comprises:

• a position encoder coupled to the moving part for measuring the position of the moving part, the position encoder generating a position signal,
• bypass elements adapted to derive the position signal to determine the acceleration of the moving part.

According to one embodiment, the exercise device is selected from the group consisting of rowing machines, indoor bicycles, lifting bars and guided load devices.

According to one embodiment, the movable part comprises a rotatably mounted motor shaft, the drive shaft is coupled to a gearbox, a pulley is coupled to the gearbox, a cable is fixed on the pulley at a first end of the cable, the cable is fixed on the handling element at a second end of the cable and the cable is able to wind on the pulley.

According to one embodiment, the exercise device comprises a human-machine interface allowing a user to adjust a coefficient of proportionality between the measured acceleration and the calculated artificial inertia contribution.

According to one embodiment, the computer is able to calculate the force to be exerted so that the force to be exerted by the electric actuator comprises an additional charge contribution having a predetermined direction, the human-machine interface allowing a user to adjust the additional charge contribution independently of the proportionality coefficient.

According to one embodiment, the man-machine interface allows a user to set the additional charge contribution to a zero value.

According to one embodiment, the biasing element is movable in a vertical direction and the computer is able to calculate the force to be exerted in the absence of force exerted by the user so that the force to be exerted by the electric actuator has a default load contribution compensating for a self-weight of the biasing element without causing spontaneous displacement of the biasing element in the absence of force exerted by the user.

• mesurer l'accélération d'une partie mobile d'un moteur électrique en réponse à la force d'un utilisateur exercée sur un élément de sollicitation lié à la partie mobile,
• générer un signal de commande en fonction de l'accélération mesurée et
• commander l'actionneur électrique avec le signal de commande de manière que la force exercée par l'actionneur électrique sur l'élément de sollicitation par l'intermédiaire de la partie mobile comporte une contribution d'inertie artificielle sensiblement proportionnelle à l'accélération mesurée

According to one embodiment, the invention also provides a method of controlling an exercise device comprising:

• measuring the acceleration of a moving part of an electric motor in response to the force of a user exerted on a biasing element connected to the moving part,
• generate a control signal according to the measured acceleration and
• controlling the electric actuator with the control signal so that the force exerted by the electric actuator on the biasing element through the moving part has an artificial inertia contribution substantially proportional to the measured acceleration

An idea underlying the invention is to simulate on an exercise machine, when using the machine by a user, a different inertia from the real inertia of the exercise machine using an electric actuator.

An idea underlying the invention is to design a machine that allows to vary the weight and inertia independently of one another.

Some aspects of the invention start from the idea of simulating, on the exercise machine, additional weight using the electric actuator.

Some aspects of the invention start from the idea of simulating, on the exercise machine, additional friction using the electric actuator.

Some aspects of the invention are based on the observation that combining the "inertia" type exercises characteristic of inertia machines and the "weight" type exercises that are characteristic of weight machines in a single machine makes it possible to save a lot of space and to invest less. expensive.

Certain aspects of the invention start from the idea of generating additional inertial forces during certain phases of a muscle exercise performed by the user and canceling these forces of inertia in the other phases of the exercise. muscular.

Certain aspects of the invention start from the idea of generating inertial forces without fixed load to create specific muscle stresses to the inversion of the movement of a mass launched on a substantially horizontal trajectory, in particular the inversion of the movement. of a runner.

The invention will be better understood, and other objects, details, characteristics and advantages thereof will appear more clearly in the course of the following description of several particular embodiments of the invention, given solely for illustrative and non-limiting purposes. with reference to the accompanying drawings.

• La figure 1 est une représentation schématique d'un dispositif d'exercice comportant un moteur.
• La figure 2 est une représentation schématique du système de commande du moteur représenté dans la figure 1.
• La figure 3 est un graphique de la position et de l'accélération en fonction du temps de la poignée décrite dans la figure 1 correspondant à une manipulation par l'utilisateur.
• La figure 4 est un graphique de la force exercée par le moteur lors d'une manipulation du dispositif de la figure 7.
• La figure 5 est un graphique de la force exercée par le moteur lors de la manipulation du dispositif conformément à la figure 3 correspondant à un premier type d'exercice.
• La figure 6 est un graphique de la force exercée par le moteur lors de la manipulation du dispositif conformément à la figure 3 correspondant à un second type d'exercice.
• La figure 7 est une représentation schématique d'une variante du dispositif d'exercice.
• La figure 8 est une représentation schématique partiellement en coupe d'un dispositif d'exercice comportant un moteur selon un autre mode de réalisation.
• La figure 9 est une représentation schématique fonctionnelle d'un système de commande du moteur représenté dans la figure 8.
• La figure 10 est une représentation schématique d'un exercice d'inversion du mouvement d'un coureur.
• La figure 11 est une représentation graphique du fonctionnement d'un comparateur à hystérésis pouvant être utilisé dans le système de commande de la figure 9.

On these drawings:

• The figure 1 is a schematic representation of an exercise device comprising a motor.
• The figure 2 is a schematic representation of the engine control system shown in the figure 1 .
• The figure 3 is a graph of the position and acceleration over time of the handle described in the figure 1 corresponding to a manipulation by the user.
• The figure 4 is a graph of the force exerted by the motor during a manipulation of the device of the figure 7 .
• The figure 5 is a graph of the force exerted by the engine when handling the device in accordance with the figure 3 corresponding to a first type of exercise.
• The figure 6 is a graph of the force exerted by the engine when handling the device in accordance with the figure 3 corresponding to a second type of exercise.
• The figure 7 is a schematic representation of a variant of the exercise device.
• The figure 8 is a schematic representation partially in section of an exercise device comprising a motor according to another embodiment.
• The figure 9 is a schematic functional representation of a motor control system represented in the figure 8 .
• The figure 10 is a schematic representation of an exercise of reversal of the movement of a runner.
• The figure 11 is a graphical representation of the operation of a hysteresis comparator that can be used in the control system of the figure 9 .

The Figures 1 and 2 illustrate an exercise device in which control methods according to the invention can be implemented. With reference to the figure 1 , the exercise device comprises an electric motor 1 which can rotate a shaft 2 and exert a torque on the shaft 2. A pulley 3 is tightly mounted on the shaft 2. A cable 4 is fixed at its first end in the groove of the pulley 3. This cable 4 can wind in the groove around the pulley 3. At the second end 5 of the cable is fixed a handle 6 through which a user can influence the device with its muscle strength when practicing muscle exercises.

The motor 1 comprises a position encoder 10 which measures the position of the motor shaft 2. The position is transmitted to an electronic card 7 in the form of a position signal 9. This electronic card 7 is adapted to receive this signal of position and uses the position signal 9 to generate a control signal. With this control signal, the electronic card 7 controls the torque generated by the motor 1 to control the force exerted by the motor 1, which is transmitted at the handle 6 via the pulley 3 and the cable 4 For this, the electronic card 7 transmits the signal of control to the motor 1 by the connection 8. This control signal is received by a power supply unit integrated into the motor 1 which, from this control signal, supplies a certain current to the motor 1. The current supplied by the supply member thus induces a torque on the moving part 2 and thus via the pulley 3 and the cable 4 a force on the handle 6. The force exerted by the motor 1 is substantially proportional to the current supplied by the power supply unit to the engine 1.

Many control methods can be implemented in such a device to produce different muscular stresses. A first example is to simulate the presence of a predetermined mass suspended from a cable, namely that the motor torque exerts on the handle 6 a constant load as to the direction and intensity.

When a user manipulates the handle 6 during an exercise it opposes the force of the engine 1 with the help of his muscular strength. For example, during a practicable exercise with this device, a user is positioned above the device and pulls the handle 6 from a low position to a high position with his hands. During this upward movement, the user must overcome the downward force exerted by the motor 1 on the handle 6. When the handle 6 arrives in the up position, the user performs the reverse movement and returns the handle 6 to the lower position while still being forced by the same force submitted in the same direction by the motor 1. During the descent, the user accompanies and brakes the movement of the handle down. The exercise device thus simulates a mass to be alternately raised and rested by the user

During this exercise, the position signal is continuously transmitted to the electronic card 7 which calculates and transmits to the motor continuously the corresponding control signal. Thus, the device controls the force generated by the motor 1 throughout the exercise.

However, a slight offset may be present between the moment when the encoder transmits the position and the torque exerted by the motor 1 because of the response time of the motor 1 to the control signal and the response time of the electronic card 7.

With reference to the figure 2 , the engine control means will now be described more specifically with reference to a second example.

The electronic card 7 here comprises a microprocessor 20. A position encoder 10 measures the position of the motor shaft 2, this position is encoded into a position signal which is transmitted via the connection 38 to the microprocessor 20. Thus, in a This measurement can be emitted every 30 ms and preferably every 5 ms. In this microprocessor 20, the position signal is transmitted to a branch member 13 via the connection 18. The branch member derives the position signal thereby generating a speed signal which is transmitted to a second branch member 14 via the connection 15. The second branch member derives the speed signal thereby generating an acceleration signal. The acceleration signal is transmitted via the connection 17 to a calculation module 12. Furthermore, the position signal and the speed signal are respectively transmitted to the calculation module 12 via the connections 11 and 16. The calculation module 12 calculates the control signal to be supplied to the motor and transmits it to the motor via the connection 19.

More specifically, the control signal is calculated from the acceleration so that the force exerted by the motor 1 on the handle 6 includes the downward load and a predetermined artificial inertia.

For this, the calculation module 12 takes into account the accumulation of the torque exerted by the motor 1 and the inertia of the rotating parts of the device connected to this motor which are the shaft 2, the pulley 3, the cable 4 and the handle 6 .

Indeed, when a user manipulates the handle 6: $$m_r\times \gamma =F_m+F_s$$

Where F _s is the force exerted by the user on the handle 6, F _m is the force exerted by the motor 1 on the handle 6 and controlled by the calculation module 12, m _r is the inertia of the moving parts reduced to the handle 6 and the mass of the handle 6 and γ is the acceleration of the handle 6.

Equation (1) corresponds to the fundamental principle of the dynamics applied to a system in translation. However, those skilled in the art will understand that torques exerted on a rotating system can be similarly modeled.

The force exerted by the motor F _m is composed of two components induced by the control signal: a fixed component F _ch representing the load and a component proportional to the acceleration F _i which represents the artificial inertia. So : $${\mathrm{F}}_{\mathrm{m}}={\mathrm{F}}_{\mathrm{ch}}+{\mathrm{F}}_{\mathrm{i}}$$

Or the force F _i is defined according to a coefficient of proportionality k : $$F_i=-k\times \gamma$$

The coefficient k is a parameter which is programmed in the calculation module 12.

Equation (1) can be rewritten: $$\left(m_r+k\right)\times \gamma =F_{\mathit{ch}}+F_s$$

In this way, if the coefficient of proportionality k used to produce the control signal is negative, namely -m _r < k <0, the device simulates an inertia less than the actual inertia of the device, that is to say the inertia of the rotating parts of the device. If the coefficient of proportionality k is positive, the device simulates greater inertia than the actual inertia of the device.

The user, through a not shown user interface can change the values of the fixed component F _ch and the proportionality factor k and thus determine the type of effort with which it wishes to practice. Thus, it is possible to independently vary the load of inertia. A wide range of types of muscle exercises can be offered to the user.

The user interface is connected to the calculation module 12 and is able to receive data on position, speed, acceleration or information calculated from these data, for example, the effort provided or the power expended. These data and information are calculated by the calculation module 12 from the acceleration, speed and position signals transmitted to the calculation module 12 respectively by the connections 17, 16 and 11. With these data and these information, the user interface may sensually solicit the user by displaying this information. The user can in this way follow the level of his effort during his physical exercises. However, these solicitations can be of different natures, solicitations are for example possible. Furthermore, the user interface comprises control members allowing the user to vary the values of the fixed component F _ch and the proportionality factor k , preferably independently of one another. These control members are for example buttons on the user interface corresponding to fixed component pairs F _ch and proportionality factor k predetermined. These couples define several types of exercises. A storage device, for example a memory in the calculation module 12, stores this information and data. Thanks to this storage, the user can follow the evolution of his performances over time.

With reference to Figures 3, 5 and 6 several particular examples of exercises that can be produced by the device presented above will be described.

The figure 3 represents the position of the handle 6 along the z axis of the figure 1 and the acceleration of the handle 6 as a function of time during the tensile stresses of the handle presented with reference to the figure 1 . The broken line curve 21 represents the position of the handle which is measured by the position encoder 10. The continuous curve 22 represents the acceleration corresponding to the position curve 21. By convention, we have oriented the z axis down on the figure 1 . The point 24 of the position curve 21 corresponds to the moment when the handle 6 is in the low position and the point 23 corresponds to the upper position of the handle.

For purposes of illustration between point 23 and point 25, the position curve 21 is substantially sinusoidal. Thus the acceleration also forms, along this period, a sinusoidal curve. Subsequently, the position curve is no longer sinusoidal and therefore the acceleration is no longer sinusoidal.

The figure 5 represents the force opposed by the motor 1 to the user as a function of time for the same time interval as the figure 3 . Curve 28 is constant at a threshold 26. Indeed, the figure 5 is a first exercise where the calculation module provides a control signal to the motor so that the force opposite the user is constant over time. For this, the calculation module produces a control signal inducing a force having a load component equal to the threshold 26 and a zero inertia component. In this exercise, the user therefore only opposes a fixed load and the actual inertia of the system.

The figure 6 represents a second exercise which partially uses the principle of the first exercise presented with reference to figure 5 . Curve 40 represents the force generated by the engine 1 during this exercise. It comprises two phases: a high phase 31 during which the curve is constant at the threshold 27 and a low phase during which the curve adopts the shape of the acceleration curve at the threshold 27. Indeed, the user is subjected to a load force corresponding to the threshold 27 when the measured acceleration is positive, that is to say here during high phases 31 of the handling of the handle where the handle is close to its high position 23. The user is however subjected to an additional inertial force oriented in the same direction as the load force when the measured acceleration is negative, that is to say during a low phase 29 when the handle arrives in low position 24 and the user decelerates the descent and then accelerates to pull the handle to the high position 23. This low phase corresponds to the phase 30 during which the acceleration is negative. In this way, the user is subjected to additional artificial inertia when he arrives in the low position and wishes to raise the handle to the high position, that is to say at the moment when his muscle solicitation is the most intense. Thus, the exercise device makes it possible to produce an additional stress that opposes the user during a reversal of the direction of movement of this user.

$$\mathrm{Si}\gamma <0,k=+k_0,\mathrm{i}\mathrm{.}\mathrm{e}\mathrm{.}k>0$$

For the implementation of the second exercise, the calculation module 12 applies a coefficient of proportionality k determined as follows: $$\mathrm{Yes}\gamma >0,k=0$$

$$\mathrm{Yes}\gamma <0,k=+{\mathrm{<figure-callout\; id="0"\; label="k"\; filenames="imgf0004.png"\; state="\{\{state\}\}">k</figure-callout>}}_0,\mathrm{i}\mathrm{.}\mathrm{e}\mathrm{.}k>0$$

Where k ₀ is a predetermined positive constant.

The exercises described above are given for illustrative purposes. In particular, the calculation module can control the coefficient of proportionality k in multiple ways. By way of example, the calculation module can vary the coefficient of proportionality as a function of the position or the speed of the handle. Thus, in one variant, the exercise device produces an additional inertia component when the handle reaches a certain position. In a variant of the exercise device, this additional inertia component is added when the speed is in a particular direction. In this way a multitude of interesting exercises for muscle development can be produced. This allows in particular to solicit the muscles of the user more intensely when they are in a particular position.

avec l'inertie du réducteur J_red et l'inertie réelle du moteur J_mot. Ainsi, si le rapport de réduction r est important, l'inertie réelle du système est fortement augmentée. Ainsi, l'utilisation d'un facteur proportionnel k négatif permet dans cette variante de compenser tout ou partie de l'inertie induite par ce réducteur. Cette compensation est d'autant plus précise que l'accélération qui est mesurée pour engendrer la force d'inertie artificielle est l'accélération de l'arbre moteur 2, de sorte que cette mesure prend en compte l'effet du réducteur, effet qui consiste à augmenter par le rapport r l'accélération au niveau de l'arbre moteur 2 par rapport à l'accélération exercée sur la poignée 6.In a variant of the device presented in figure 1 , the drive shaft 2 is connected to a speed reducer having a reduction ratio r. The presence of such a gearbox makes it possible to generate relatively large forces while reducing the size of the motor, in order to miniaturize the device. The pulley 3 is fixed on an output shaft of the gearbox. In this variant, the presence of a reducer greatly increases the real inertia of the moving parts of the motor 1 brought back to the handle 6. The real inertia of the device is also increased by the reduced inertia of the rotating parts of the gearbox. The inertia of the motor and the gearbox brought back to the output of the gearbox J _tot can be written: $${\mathrm{J}}_{\mathrm{early}}={\mathrm{J}}_{\mathrm{red}}+{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="imgf0001.png,imgf0004.png"\; state="\{\{state\}\}">r</figure-callout>}}^{\mathrm{2}}{\mathrm{J}}_{\mathrm{word}}$$

with the inertia of reducer J _red and the real inertia of motor J _word . Thus, if the reduction ratio r is large, the real inertia of the system is greatly increased. Thus, the use of a proportional factor k negative in this variant to compensate all or part of the inertia induced by the reducer. This compensation is all the more precise as the acceleration which is measured to generate the artificial inertia force is the acceleration of the motor shaft 2, so that this measurement takes into account the effect of the gearbox, which effect consists in increasing by the ratio r the acceleration at the level of the motor shaft 2 with respect to the acceleration exerted on the handle 6.

The very simple exercise device described with reference to Figures 1 and 2 is given as an illustration, the invention is therefore not limited to this type of exercise device. In particular, the invention can be adapted to any type of exercise machine that solicits any part of the body. By way of example, the invention may be adapted to constitute a rowing-type device, an indoor bicycle or a lifting bar.

With reference to the figure 7 there is shown an exercise device 50 for exerting the muscles of the arms in traction and thrust in which control methods according to the invention can be implemented.

The device 50 comprises two levers 53 which can be moved alternately forwards and backwards by a user. The levers 53 are each coupled to an electric motor 54 which is controlled by the control device 55. According to one embodiment, the motors 54 are controlled so as to generate a force represented by the curve 33 of the figure 4 . For simplification purposes, the rotary motion of the levers is approximated in a linear motion along the x-axis.

So, the figure 4 represents the effort opposed to a user as part of the exercise device shown on the figure 7 . The curve 33 represents the force generated by the motor and has a value proportional to the acceleration curve 30. It is assumed that a user solicits the lever 53 so that the measured position and the acceleration are the same as on the figure 3 , the x axis here replacing the z axis. In this type of exercise, the control device 55 subjects a control signal to the motors 54 which does not induce a charge component. Only a component of artificial inertia is produced by the motors 54. Thus, the effort experienced by the user is proportional to the acceleration and therefore corresponds to a simulated inertia without load that is greater than the actual inertia of the device.

This type of stress with artificial inertia without additional load is also interesting in an exercise machine soliciting the leg muscles. Indeed, the muscular stress produced by the motor when it is controlled in this way corresponds substantially to the muscular stress required to reverse the movement of a runner on a horizontal ground. Such an exercise is illustrated on the figure 10 .

On the figure 10 , the runner 34 is initially running at high speed in the x-axis direction, as shown schematically by the speed vector 35. At the end of the exercise, the runner 34 is running at high speed. speed in the opposite direction to the x-axis, as represented schematically by the speed vector 36. During the exercise, the rider 34 therefore had to slow down his movement until it stopped, for example at point x0 , then re-accelerate in the other direction. The muscles of the rider 34 were therefore solicited during this exercise essentially to overcome the inertia of the rider himself, oriented along the x axis. The force of gravity being perpendicular to the movement, it does not create any particular muscular solicitation in this exercise, that is to say that the muscular solicitation specific to the exercise is a solicitation of pure inertia. The exercise machine programmed to produce this type of solicitation is all the more advantageous as this race reversal situation is very common in ball sports, for example rugby or football.

Similarly, a control program associating the artificial inertia force with a constant load makes it possible to produce a muscular solicitation similar to the accomplishment of the same exercise on a sloping ground.

A device for simulating an additional viscous friction force will now be presented. The device is similar to the device described with the figure 7 and comprises a microprocessor having the same structure as the microprocessor 20 of the control system described in the figure 2 . The force exerted by the engine here comprises three components. The first two components correspond to the load component and the inertia component described above. The third component is a viscous friction component. So : $${\mathrm{F}}_{\mathrm{m}}={\mathrm{F}}_{\mathrm{ch}}+{\mathrm{F}}_{\mathrm{i}}+{\mathrm{F}}_{\mathrm{fv}}$$

Where the force F _fv , corresponding to the viscous friction component, is defined according to a coefficient of proportionality k ₂ and according to the speed v of the handle: $${\mathrm{F}}_{\mathrm{fv}}={\mathrm{<figure-callout\; id="2"\; label="k"\; filenames="imgf0001.png,imgf0004.png"\; state="\{\{state\}\}">k</figure-callout>}}_2\times v$$

The speed v is determined by the calculation module 12 by means of a speed signal which is transmitted to the calculation module 12 via the connection 16.

Thus, when the user moves the levers in one direction, the motor generates a torque on the lever comprising the viscous friction component proportional to the speed of movement of the lever in addition to a component of inertia. This viscous friction component causes an additional stress which opposes the direction of movement of the user. In this way, the device simulates a viscous friction that can be produced by a machine comprising a finned system.

The coefficient k ₂ can be a constant stored in the memory of the microprocessor 20. In the same way as the inertia component, the calculation module 12 can control the coefficient of proportionality k ₂ in multiple ways. By way of example, the calculation module can vary the coefficient of proportionality k ₂ as a function of the position of the handle.

With reference to figures 8 and 9 another exercise machine 60 using an electric motor will now be described. The machine 60 has a relatively similar shape to a weight machine known as a squat machine. But it can provide a much wider range of muscular solicitations.

The structure of the machine comprises a metal base 61 placed on the ground, shown in section on the figure 8 , and a guide column 62 vertically fixed to the base 61. The upper surface of the base 61 is a platform 68 for receiving an athlete, for example in standing position as shown in ghost line. A carriage 63 is slidably mounted on the column 62 by guide means not shown, so as to translate vertically along the column 62. According to one embodiment, the carriage 63 is a four-sided structure which completely surrounds column 62, one and the other having a square section. The carriage 63 carries gripping rods 69 which extend above the platform 68 and are intended to be engaged with the athlete, for example at the level of his shoulders or his arms or legs according to the invention. desired exercise.

A transmission belt 64 is mounted in the column 62 and extends between a idler pulley 65 pivotally mounted at the top of the column 65 and a driving pulley 66 pivotally mounted in the base directly above the column 62. belt 64 is a toothed belt that makes a round-trip closed loop between the pulleys 65 and 66 so as to be coupled without slipping to the drive pulley 66. The carriage 63 is secured to one of the two branches of the belt 64, by example by means of rivets 67 or other fastening means, so that it is also coupled without slipping to the drive pulley 66, any rotation of the pulley 66 resulting in a vertical translation of the carriage 63. Preferably, the belt 64 is formed of an AT10 toothed belt whose two ends are fixed to the carriage 63, so as to close the loop at the carriage 63.

A motor unit 70 is housed in the base 61 and coupled to the drive pulley 66 by means of a speed reducer 71. More specifically, the speed reducer 71 comprises an input shaft 72 coupled without sliding to the motor shaft of the motor group 70, which is shown in more detail on the figure 9 , and an output shaft 73 which carries the driving pulley 66. The speed reducer 71 imposes a reduction ratio r between the rotation speed w1 of the shaft 72 and the rotation speed w2 of the shaft 73, namely wl / w2 = r. According to embodiments, the reduction ratio r is chosen between 3 and 100, and preferably between 5 and 30.

The machine 60 also comprises a control console 74 which can be integral with the base 61 or independent thereof. In addition, a power cable 75 out of the base 61 to be connected to the power grid. The machine 60 does not require exceptional electrical power and can therefore be powered by a common home network.

The figure 9 represents more precisely the motor group 70 and its control unit 80, which is also housed in the base 61. The motor unit 70 comprises an electric motor 76, for example an autopilot synchronous motor, and a current controller 77 which controls the current supply 78 of the engine 76.

It is recalled that the synchronous motor autopilot has a constant rotor flow. This flux is created by permanent magnets or coils mounted in the rotor, while the variable stator flux is created by a three-phase winding to orient it in all directions. The electronic control of this motor is to control the phase of the current waves so as to create a rotating field, always ahead of 90 ° on the field of the magnets, so that the torque is maximum. Under these conditions, the engine torque on the drive shaft 2 is proportional to the stator current. This current is precisely controlled in real time by the control unit 80 via the current controller 77.

For this purpose, the control unit 80 comprises a low-level controller 81, for example of the FPGA type, which receives the position signal 83 from the position encoder 84 of the motor shaft 2 and performs real-time calculations. from the position signal 83 to determine the instantaneous values of the position, the speed and the acceleration of the motor shaft 2. The position encoder 84 is for example an optical device which provides two squared signals in quadrature according to the technique known.

The high-level controller 82 includes a memory and a processor and executes complex control programs from the information provided in real time by the low-level controller 81. Possible control programs have been described above with reference to the Figures 3 to 6 .

The control console 74 is connected to the high-level controller 82 via a wired or wireless TCP / IP link 85, and has an interface allowing the athlete or his trainer to select pre-recorded exercise programs or to adjust them. precisely and in a personalized way the parameters of such a program. In the example shown, the interface is a touch screen 86 which includes a slider 87 for adjusting the value of the load F _ch along a predetermined scale, for example 0 to 3000 N, and a slider 88 to adjust the value of the coefficient k along a predetermined scale, that is to say the artificial inertia force F _i .

Depending on the exercise program executed, the high-level controller 82 processes the information provided in real time by the low-level controller 81 and calculates the instantaneous torque to be exerted by the motor group 70. The base controller Level 81 generates a control signal 90 corresponding to this instantaneous torque and transmits the signal 90 to the current controller 77, for example in the form of an analog control voltage varying between 0 and 10V. Alternatively, a CAN digital interface may also be used.

The control programs for simulating different exercises can be very numerous. Preferably, regardless of the detail of the program, it is always the athlete who controls the machine 60 and the machine 60 that reacts to the solicitation exerted by the athlete on the gripping bars 69. For this, it is preferable that the machine 60 can react quickly to changes of direction imposed by the athlete, despite the friction that inevitably exist in such a mechanical system.

For this, according to one embodiment, the high-level controller 82 implements a friction compensation algorithm that will now be explained.

$$\mathrm{Fc}-\mathrm{b}<\mathit{Fch}0<\mathit{Fc}+a$$

Note the mass of the truck 63. Note Fc = mc.g, the force that must impose the motor 76 on the belt 64 to compensate for the weight of the carriage 63 without the user does not support any load. The algorithm uses parameters a and b defined by the fact that if the motor 76 applies Fc + a the carriage 63 is at the limit of the movement in the positive direction, upwards, and if the motor 76 applies Fc -b the trolley 63 is at the limit of the setting in motion in the negative direction, downward. These parameters a and b can be measured experimentally. The algorithm governs the passage of the force Fc + a to the force Fc b in the event of a change in the direction of the stress exerted by the user. The algorithm applies laws that use the linear velocity v of the carriage 63 and a coefficient kf, namely: $$\mathrm{Fch}0=\mathrm{Fc}+\mathrm{kf}\mathrm{.}\mathrm{v}$$

$$\mathrm{Fc}-\mathrm{b}<\mathit{Fch}0<\mathit{Fc}+\mathrm{at}$$

Where Fch0 denotes the force imposed by default on the belt 64 by the motor 76, namely the value that is applied when the cursor 87 is placed on the graduation 0. In other words, if the cursor 37 is placed on the graduation 3000N for an exercise program planning to exercise this load alternately in both directions, and that the carriage 63 weighs 60kg, the electric motor will actually exert a force of about 3600 N in climb and 2400 N in descent.

Thus, the higher the coefficient kf, the faster the machine reacts to changes in direction imposed by the user. Beyond a certain limit, a very strong reactivity could require a frequency filtering of the speed measurement, for example of the low-pass type of the first order.

According to the selected program, for example when an artificial inertia force proportional to the acceleration and / or a viscous force proportional to the speed is applied by the engine, or when the program provides different reactions in the concentric direction and in the the eccentric direction, the force to apply calculated can undergo a discontinuity at the time of reversal of the direction, which is necessarily detrimental to the comfort of use of the machine.

According to one embodiment, the high-level controller 82 implements an algorithm to avoid these discontinuities. To do this, the controller 82 detects a change of direction by the passage of the speed signal in a hysteresis comparator shown schematically on the figure 11 .

When starting the concentric phase, if the speed v> ε, the controller 82 triggers the passage from F2 to F1. This variation is at a constant rate of change, for example of the order of 200 N / s.

Similarly, during the passage from the concentric phase to the eccentric phase, when the speed becomes negative and passes under a threshold v <-ε, the controller 82 triggers the transition from F1 to F2. The threshold value ε is chosen so as to ensure sufficient stability, namely that the engine does not go from F1 to F2 untimely when the athlete decides to stop during his movement.

On the figure 11 it should be noted that force-versus-velocity curves between F1 and F2 values are not imposed by the system and depend in fact on the user's behavior, ie, how he varies the speed in a function of time, since the system imposes a rate of variation of force as a function of time.

In addition, the control program can prevent the motor from making more than two consecutive changes if the difference in position of the moving part between the two changes does not exceed a certain limit, for example of 10 cm.

In other embodiments, the exercise program may also comprise an elastic force contribution F _e defined as a function of a coefficient of proportionality k ₃ and as a function of the position z of the carriage 63: $${\mathrm{F}}_{\mathrm{e}}=k_3\times \left(z-z0\right)$$

0 where z is a height adjustable reference and the z position is determined by the low-level controller 81.

It is therefore understandable that many exercise programs can be designed by combining additive contributions selected from the group comprising an artificial inertia contribution proportional to the measured acceleration, a viscous friction contribution proportional to the measured speed, a elastic contribution proportional to the measured position, and a predetermined load contribution. According to one embodiment, the human-machine interface allows the user to independently adjust the parameters of each of these contributions, in particular the coefficients k , k ₂ and k ₃ .

Although the embodiments described above include rotary motors, the control methods described above may be employed with any other type of electric actuator. In particular, a linear motor can be used to generate a force on the handling element.

Moreover, the calculation of the control signal can be performed in different forms, unitarily or distributed, by means of hardware and / or software components. Useful hardware components are ASIC specific integrated circuits, FPGA programmable logic networks or microprocessors. Software components can be written in different programming languages, for example C, C ++, Java or VHDL. This list is not exhaustive.

Although the invention has been described in connection with several particular embodiments, it is obvious that it is not limited thereto and that it comprises all the technical equivalents of the means described and their combinations if they are within the scope of the invention.

The use of the verb "to include", "to understand" or "to include" and its conjugated forms does not exclude the presence of other elements or steps other than those set out in a claim. The use of the indefinite article "a" or "an" for an element or a step does not exclude, unless otherwise stated, the presence of a plurality of such elements or steps. Several means or modules can be represented by the same hardware element.

In the claims, any reference sign in parentheses can not be interpreted as a limitation of the claim.

Claims (14)

1. An exercise device comprising
   a load element (6, 69) intended to be displaced by the force of a user,
   an electric actuator (1, 76) comprising a moving part (2), the load element (6, 69) being linked to the moving part and the load element being able to displace the moving part,
   a computer (12, 80) suitable for computing a force to be exerted by the electric actuator and for generating a control signal for the electric actuator as a function of the computed force to be exerted, in such a way that the force exerted by the electric actuator (1) in response to the control signal corresponds to the computed force to be exerted and
   an acceleration sensor coupled to the moving part (2) for measuring the acceleration of the moving part and for transmitting the measured acceleration to the computer (12, 80),
   the electric actuator being able to exert a force on the load element (6, 69) via the moving part in response to the control signal,
   in which the computer (12, 80) is able to compute the force to be exerted as a function of the acceleration measured by the acceleration sensor,
   characterized in that the device also comprises:

   - a memory of the computer in which is stored a coefficient of proportionality between the measured acceleration and an additive contribution of artificial inertia, and

   - a human-machine interface (86) enabling a user to set the coefficient of proportionality,

   the computer being able to compute the additive contribution of artificial inertia as a function of the measured acceleration and of the coefficient of proportionality, the force to be exerted computed by the computer as a function of the measured acceleration including the additive contribution of artificial inertia proportional to the measured acceleration obtained by the computer as the result of a multiplication of the measured acceleration by the coefficient of proportionality stored in the memory, in such a way that the force exerted by the electric actuator (1, 76) in response to the control signal includes the additive contribution of artificial inertia proportional to the acceleration measured by the acceleration sensor and to the coefficient of proportionality stored in the memory.
2. The exercise device as claimed in claim 1, characterized in that the computer (12, 80) is able to vary the coefficient of proportionality as a function of at least one parameter chosen from the position, the speed and the acceleration of the moving part.
3. The exercise device as claimed in claim 1 or 2, characterized in that the computer (12, 80) is able to compute the force to be exerted in such a way that the force to be exerted by the electric actuator (1, 76) includes an additive contribution of additional load exhibiting a predetermined direction.
4. The exercise device as claimed in claim 3, characterized in that the computer (12, 80) is able to compute the force to be exerted in such a way that the additive contribution of artificial inertia is oriented in the same direction as the contribution of predetermined direction when the measured acceleration is in the direction opposite the contribution of predetermined direction.
5. The exercise device as claimed in claim 4, characterized in that the computer (12, 80) is able to compute the force to be exerted in such a way as to cancel the additive contribution of artificial inertia when the measured acceleration is in the same direction as the contribution of predetermined direction of the electric actuator (1, 76).
6. The exercise device as claimed in one of claims 1 to 5, characterized in that the link between the load element (6, 69) and the moving part includes a speed reducer for gearing down the force of the motor.
7. The exercise device as claimed in one of claims 1 to 6, characterized in that it comprises a speed sensor suitable for measuring the speed of the moving part (2) and that the computer (12, 80) is able to generate the control signal in such a way that the force exerted by the electric actuator (1, 76) includes an additive contribution of viscous friction substantially proportional to the speed measured by the speed sensor.
8. The exercise device as claimed in one of claims 1 to 7, characterized in that the electric actuator (1, 76) is a linear motor or a rotary motor.
9. The exercise device as claimed in one of claims 1 to 8, characterized in that the acceleration sensor comprises:

   a position coder (10, 84) coupled to the moving part (2) for measuring the position of the moving part, the position coder (10, 84) generating a position signal,

   shunt elements (13, 14) suitable for shunting the position signal to determine the acceleration of the moving part (2).
10. The exercise device as claimed in one of claims 1 to 9, characterized in that the exercise device is selected from the group comprising rowing machines, exercise bicycles, lifting bars and guided load appliances.
11. The exercise device as claimed in one of claims 1 to 10, characterized in that the computer (12, 80) is able to compute the force to be exerted in such a way that the force to be exerted by the electric actuator (1, 76) includes an additive contribution of additional load exhibiting a predetermined direction, the human-machine interface (86) enabling a user to set the additive contribution of additional load independently of the coefficient of proportionality.
12. The exercise device as claimed in claim 11, characterized in that the human-machine interface (86) enables a user to set the additive contribution of additional load to a zero value.
13. The exercise device as claimed in one of claims 1 to 12, characterized in that the load element (69, 63) can be displaced in a vertical direction and that the computer (12, 80) is able to compute the force to be exerted in the absence of force exerted by the user, in such a way that the force to be exerted by the electric actuator (1, 76) includes a default additive contribution of load compensating a specific weight of the load element (69, 63) without causing any spontaneous displacement of the load element (69, 63) in the absence of a force exerted by the user.
14. A method for controlling an exercise device comprising:

    measuring the acceleration of a moving part (2) of an electric actuator in response to the force of a user exerted on a load element (6, 69) linked to the moving part,

    computing a force to be exerted by the electric actuator as a function of the measured acceleration and

    generating a control signal for controlling the electric actuator (1, 76) with the control signal in such a way that the force exerted by the electric actuator (1, 76) in response to the control signal corresponds to the computed force to be exerted,

    characterized by the steps of:

    - providing a human-machine interface (86) enabling a user to set a coefficient of proportionality between the measured acceleration and an additive contribution of artificial inertia,

    - storing the coefficient of proportionality in a memory,

    - multiplying the measured acceleration by the coefficient of proportionality to obtain the additive contribution of artificial inertia, and

    - obtaining the force to be exerted computed as a function of the measured acceleration including the additive contribution of artificial inertia proportional to the measured acceleration, in such a way that the force exerted by the electric actuator (1, 76) on the load element (6, 69) via the moving part (2) in response to the control signal includes an additive contribution of artificial inertia proportional to the measured acceleration.

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