WO2015083057A1

WO2015083057A1 - Machine for physical exercise

Info

Publication number: WO2015083057A1
Application number: PCT/IB2014/066471
Authority: WO
Inventors: Pierpaolo Lucchetta
Original assignee: Domino S.R.L.
Priority date: 2013-12-03
Filing date: 2014-12-01
Publication date: 2015-06-11
Also published as: ITTV20130199A1

Abstract

In order to improve the performance of a machine (50) for physical exercise with a resistance element that can be moved by a user with the muscular force in a certain movement range, provided that a predefined 5 reference resistance response for (Fref) that may vary according to the movement range is imposed on the element by means of a drive (60), a method to control the machine in feedback is presented: it consists in acquiring a signal (x) indicating the position of the element within the movement range and/or the physiological condition of the user, 10 calculating a linear combination (C) of n-th derivatives, n>=0, of the indicative signal in order to obtain the reference resistance response, wherein coefficients (ai) of the linear combination have programmable values. Therefore, the coefficients of the linear combination have 15 programmable values as a function of a variance (E) between a reference programmed response (Fref) and the actual response applied to the resistance element by the user, thus increasing in a simple and repeatable way the possible exercise which can be performed with the machine. 20

Description

MACHINE FOR PHYSICAL EXERCISE

The invention refers to a machine or device for physical exercise and to its control method.

Modern machines or devices for physical exercise are generally provided with a resistance element (dumbbell, barbell, plate to push, string to pull, etc.) that can be moved by a user with muscular force.

The most recent machines are smart, so much so that the resistance response of the element may follow a programmed reference signal by means of a drive. The machine can respond in real time because the references of the control feedback loop are calculated as a function of a variable depending on the activity of the user, see for example paragraphs 26, 70, 95-96, 139 of US 2001/0195819. Also US 8 360 935 proposes the same idea.

Basically classic concepts of digital automatic feedback controls are applied. The drive is usually a Mot engine in a feedback loop 82 (Fig.1). A variable x provided by a sensor on the resistance element is sampled and an engine is driven so that the difference or error E between x and a signal or reference value F_ref is small, that is x follows the pattern of F_ref. In smart machines, F_ref is a programmable function of time t and/ or of x, that is F_ref = F_ref (t, x); see for example the graphs in fig. 3 and 5 of US 2001/0195819 and the upper part of fig. 1 as well as WO2013/060999.

These machines, even though they increased the variants of man- machine interaction greatly, have disadvantages.

First of all they can offer to the athlete only one type of physical exercise at a time (isotonic, spring simulation, simulation of a mass or isokinetic). Furthermore, they cannot really respond to the behavior of the user. A reference is imposed to the resistance element, mistakenly assuming that the athlete can always follow it. This is not true, especially in the machines for sports rehabilitation, where it is rather the contrary.

For example, during an isotonic exercise the athlete exceeds the constant resistance force and the machine can react either according to the inertia of its components or in a programmed way by simulating a viscous friction (US 8 360 935 column 8) , that is the same as adding a multiplier on the velocity loop. In any case the freedom of control on the element W is very limited; for example, there cannot be different viscous responses in different points of its movement range.

Whereas it is undoubted that a high level training, customized and even more so when it is for rehabilitation, requires that the machine is programmed in each detail of its response. WO20 13/060999, for example, permits to set the coefficients of a dynamic equation for the element W, but coefficients can be set from the keyboard and remain constants during the whole exercise.

The main purpose of the invention is to solve at least one of these problems. The invention is defined in the enclosed claims, where the dependent ones define advantageous variants.

A method is proposed to control a resistance element in feedback, belonging to a device or machine for physical exercise that can be moved by a user with muscular force in a certain movement range. A predefined reference resistance response which may vary according to the movement range is imposed to the element by means of a drive. An indicative signal of the element position is measured within the movement range and/or of the current physiological data of the user. A linear combination of n-th derivatives, n>=0, of the indicative signal is calculated to obtain the reference resistance response. One or each one of the coefficients of the linear combination has programmable values as a function of a variation (E) between a programmed reference response (F_ref) and the actual response applied to the resistance element by the user.

It is therefore possible to calculate one or each coefficient as a function of a variation or deviation between at least one of the n-th derivatives and a reference for that derivative, and the reference resistance response is calculated as a function of the variation. A comparison can be made either with a curve of the whole movement range or with the different references for the derivatives. These references can vary for each derivative and/or can be programmable, for example sample by sample, as a function of time and/or of the abovementioned signal.

In the method for obtaining the reference resistance response, it is possible to calculate the linear combination of the n-th derivatives, n>=0, of an indicative signal of the variation between the force applied to the element and the force actually applied by the user.

The abovementioned linear combination allows to program several variables of exercise and / or of control of the received signal in a simple and repeatable way, in particular it permits to easily program sequences of many different exercise types (among which the known exercises) or to change the type of simulated exercise during the exercise session. The mathematical model used to calculate the reference resistance response can be defined by the abovementioned coefficients, therefore changing them during the session and/ or upgrading them with easy programming makes the machine management much easier and provides a repeatable parametrization, that can even be exported, of an exercise created ad hoc.

It should be noted that in the method, to obtain the reference resistance response, it is possible to calculate a linear combination of n- th derivatives, n>=0, of an indicative signal also or only of the user's physical condition, wherein the coefficients of the linear combination have programmable values as indicated below.

Advantageously, coefficients can have programmable value as a function of the indicative signal. It is therefore possible for example to program a response of the machine according to the actions or physical condition of the user, e.g. by setting different response models of the resistance element within the movement range, for example by conditioning or not conditioning when preset and/ or programmable conditions take place. The number of programmable exercises increases if coefficients have different programmable values for each direction of the movement range.

These coefficients can have programmable values for example as function of time (e.g. for exercises in which resistance varies over time) and / or as a function of a variance or deviation between a programmed reference resistance response and the actual response applied by the user on the resistance element. In the latter case the response of the resistance element takes into consideration or depends on the actual behavior of the user. If for example he does not manage to exceed a preset load, the quantity of the excess can be determined and then automatically reduced, for example in the segment of the movement range where the muscular force is weaker.

In other words, the error between the indicative signal and a reference given is used to modify the response of the machine, this system allows to have more operating variants: it is possible to program the behavior of the machine when the user does not follow the reference.

The method also permits to calculate a variance or deviation between at least one of the n-th derivatives and a reference for this derivative, and the reference resistance response is calculated as a function of the variance. Unlike the previous case, here the comparison is not made with a curve of the whole movement range but with several references for the derivatives, references which can be different for each derivative and/or programmable, for example sample by sample, as a function of time and/or of the abovementioned indicative signal.

In the method for obtaining the reference resistance response it is possible to calculate the direct linear combination of n-th derivatives, n>=0, of an indicative signal of the variance between the force applied to the element and the force actually applied by the user, when the coefficients of the linear combination have programmable values like in this case. Preferably the indicative signal is acquired from the torque applied on the resistance element, from its position, from the time and from the mathematical model of the system, not by using a force sensor. This permits for example to save unwieldy and expensive load cells, which are difficult to apply on a string to pull.

A machine designed to implement the method is also proposed. It is provided with the means necessary to carry out all or some of the phases described here, in particular the claimed phases.

In general the device or machine for physical exercise proposed has a resistance element that can be moved by a user with muscular force in a certain movement range and controlled in feedback by a drive which imposes a specific resistance response that can vary according to the movement range. It includes devices for measuring or a detector (e.g. a position sensor) of an indicative signal of the element position within the movement range and / or of the current physiological data of the user (e.g. a sensor on the user), devices or an electrical circuit to calculate (e.g. a CPU or a microprocessor or electronic board) a linear combination of n-th derivatives, n>=0, of the indicative signal in order to obtain the reference resistance response, devices or programming element (e.g. a PC or a data input interface such as keyboards or a touch screen) to program the coefficients of the linear combination, wherein programming devices and/ or devices for calculating can be in their turn programmed or designed to allow the programming of the coefficients (all or some):

- as a function of the indicative signal; and / or

-differently for each direction of the movement range; and/or

- as a function of time; and / or

-as a function of the variance between a programmed reference resistance response and the response actually applied to the resistance element; and/ or

- as a function of the variance between at least one of n-th derivatives and a reference for this derivative, and the reference resistance response is calculated as a function of the variance; and/or

- in general as described above for each variant of the method, with the same advantages.

An accessory module is also proposed , it can be applied to a machine for physical exercise and it comprises

an input line to acquire an indicative signal of the position of the element within the movement range and/ or the current physiological data of the user,

devices or a circuit for calculating (e.g. a CPU or a microprocessor or an electronic board) a linear combination of n-th derivatives, n>=0, of the indicative signal to obtain a reference resistance response, devices or a programming element (e.g. a PC or a data input interface such as keyboards or touch screens) to program the coefficients of the linear combination; and an output line for a signal which contains the information on the calculated reference resistance response.

The accessory module too can in general carry out every variant of the method and/ or to contain the elements of the abovementioned machine, with the same advantages.

The advantages of the invention will be clearer thanks to the following description of a preferred model of machine, with the support of the enclosed drawing in which

Fig. 1 shows a block diagram of a preferred machine;

Fig.2 shows an axonometric view of a preferred machine;

Fig. 3 shows an axonometric view of a variant of a preferred machine;

In the figures, the same numbers indicate the same parts or parts conceptually similar.

Fig. 2 shows an example of machine 50 with a Mot electrical engine controlled by a drive 60, and it drives a movable resistance element, e.g. a grip 58 attached to a string 56 which can be pulled by the user with muscular force. The string 56 e.g. is sent back in a known way on pulleys 54 and pulled in a known way from a motor pulley 55 coupled to the Mot engine.

The goal of the machine 50 is to drive the Mot engine to control the element 58 with a regulated force Fmot (see figure 1), so that the user receives the desired resistance while working. To this end, a negative feedback loop 82 is used that can be schematized with reference F_ref, open loop transfer function G, transfer function G_mot of the Mot engine, and feedback factor H. All can be included in the drive 60.

The drive 60 is driven for example through a torque or force reference F_ref generated outside the feedback loop.

There is an electronic controller 70, outside the drive 60, provided with a processing unit 72 (e.g. a microprocessor) for calculating and generating a reference signal F_ref applied with a line 90 coming from unit 72. The unit 72 can be implemented with hardware or be a part of a computer program. The force/ torque F_mot of the Mot engine is given by the controller 70 through processing or by calculating or determining the reference F_ref, which therefore determines the reference of the drive 60 that will control its internal Mot engine in order to follow the reference.

The controller 70 can directly receive a feedback signal x on a line

62. In particular the machine 50 may comprise a force sensor to measure the force applied by the user on the element 58, e.g. an acceleration sensor or a load cell, or a position sensor to transmit a signal of the position of the element 58 along its movement path, i.e. the movement range.

In this case, the x signal is taken from one or more of these sensors. However, it is appropriate to use a drive 60 with engine with internal encoder providing an indirect kinematic value (fig.1) for the position of the element 58.

Being x the value or values acquired through the abovementioned sensors or directly from the drive 60, and if x indicates the position within the movement range or the stroke of the resistance element 58, it can conventionally take on values Xmin < X < Xmax, with Xmin aS the beginning of the movement and x_max as the end.

See fig. 1. In this example the reference signal F_ref is calculated by the unit 72 with a formula which comprises the linear combination of time derivatives of x:

Fref = Fo + ao * x + ai * dx/dt + a₂ * d²x/dt² + ...+ a_n * dⁿx/dtⁿ. (C)

Fo is optional.

Fo and/or every ai i-th coefficient (0<=i<=n) can be programmed by the user through the module 72 (the concept is schematized in fig. 1 with updating line and influence 92), for example by entering data and values with the help of a keyboard 68 and/or a display 66 (e.g. a touch screen), connected to the unit 72 and managed by it.

It should be noted that derivatives ftx/dV can be, as already mentioned, generated or calculated also in the drive 60 and read on the line 62.

Fo and/ or the coefficients can be either constants or programmable, for example as a function of one or more variants, for example, Fo and/or ai coefficients may independently have values of real numbers or zero.

E.g. : for ao <> 0 and aj = Fo = 0 for j>0 a spring resistance response is simulated; for Άι < > 0 and aj = Fo = 0 per j<> l a viscous resistance response is simulated; for a.2 < > 0 and aj = Fo = 0 for j<>2 a resistance response of a mass to be lifted is simulated: for a,- = 0 for j>=0 with Fo constant (isotonic exercise).

It is therefore possible to program responses of the resistance element that are combinations of the previous ones by simply giving the appropriate values to the ai and/or Fo coefficients. In order to increase the possible responses of the machine 50, ai and/ or Fo coefficients may not only be constants but also programmable functions of time and/ or of variable x and/ or its derivatives. Therefore, for example, it is possible to simulate a resistance force of a mass or weight which varies over time or with dⁱx/dtⁱ, which allows to change the load for example on a dumbbell or barbell according to the opening or closing angle of the elbow joint.

Furthermore, the machine 50 can be preferably programmed independently for the two directions of the movement range, for example lifting or lowering a barbell.

In this case it is sufficient to separately store the punctual value of the ai and/or Fo coefficients between 0 and x_m (outward movement) and between x_m and 0 (return movement), and/ or for the corresponding time values. In particular, it should be noted that the machine 50, even independently from formula (C), can advantageously control the Mot engine independently for the two directions of the movement range. Exercises can therefore have different and programmable responses for the two different trajectories or movements of the resistance element. Fig. 1 schematically shows that unit 70 can arithmetically calculate (see the updating lines 92) ai coefficients and the terms ftx/dV and/ or Fo separately through the calculation module 72 and selectively add the factors Fo and ai* ftx/dV to create the signal F_ref.

Possible known converters A/D and D/A for the digitalization / and analog reconstruction of the signals and gain blocks are not shown for the sake of simplicity. Known adder, multiplier or arithmetic stages executing the mathematical functions described here are not shown either.

If the unit 72 is a microprocessor, calculation can be made by using a suitable program, and the coefficients F0 and ai can be the content of regulators or memory.

The coefficients ai and/ or Fo can be calculated in real time according to programmable algorithms or functions, or more efficiently they can be stored in look-up tables in a memory 80 and read when necessary. The user can for example also import some customized coefficients ai and / or Fo in the memory 80 to program a specific exercise and/ or can save them in the memory so that they can be recalled in later sessions with no need to re-program the machine 50 every time.

The unit 70 can also make the abovementioned data of the memory 80 available externally, for example via USB or serial port or network card (not shown), to make it possible to export customizations to other machines. The unit or module 72 can also carry out additional checks such as maximum or minimum velocity check for the resistance element, that is monitor the value of dx/dt and/ or the product a^dx/dt. For example, the unit 72 continuously examines the value dx/dt and, according to its value (for example by comparing it with maximum or minimum threshold values), acts and generates a signal Fref without considering and prevailing on the result of the linear combination (C); or on the basis of the threshold value reached or surpassed, it modifies the coefficients ai and/or Fo in a programmed way. This means that for example when the machine simulates a specific weight for the resistance element, it can monitor the repetition speed of lifting exercises. If the speed is not included within certain threshold values, for example because the user is fatigued or is under little strain, the machine may modify the simulated load in real time in order to obtain a more effective exercise.

In the previous examples, the machine 50 can also vary the transfer function between x and its derivatives and F_ref in a discontinuous and/or non-linear way and in any case also in a programmable way. The negative feedback loop including the unit 72, or the unit 72 itself, can integrate or implement algebraic or mathematical blocks S to calculate the error or deviation i-th Ern between a given reference x_ref and one of the derivatives i-th of x (in this case preferably

The error Ern can be calculated as a variance between x_ref and one of the derivatives i-th of x, for example as a simple difference, in absolute value or with sign, or with a generic mathematical rule, or as argument of a mathematical function or as a mathematical model having Ern as argument or parameter. Fig 1, for example, shows the calculation of Err 2 by difference.

Therefore F_ref is calculated as a function of Ern and the loop acts to minimize it, giving the value x_ref to the selected i-th derivative.

For example, in isotonic exercises, it is possible for example to have d²x/dt² = constant and a.2= mass to be moved; the machine 50 also permits to perform an isotonic exercise with variable velocity and acceleration, thanks to the real-time calculation and updating of the coefficients ai and/ or Fo, or to the intervention of the abovementioned threshold values on some derivative of x to affect parameters of formula (C) or exclude it from control and use a different algorithm to generate Fref.

Considering that the athlete may react in different ways to the resistance F_mot or to a given reference which is a function of ftx/dV and / or Fo, the machine 50 can be further improved allowing to program one or each coefficient ai and/ or Fo also or only with respect to variances between a given reference x_ref and one of the i-th derivatives of x, which is an Ern. In other words, ai = f(Ern) and/ or Fo = f(Ern), paving the way to many new dynamic controls for the resistance element. For example, in isotonic exercises the athlete can either pull or push the resistance element (when different from the string 58) with greater force than the given force, causing its movement. The machine 50 allows to set the dynamic response of the resistance element on the basis of this movement, for example by simulating a programmable viscous friction and/or setting a speed limit.

Notably, this variant allows results which were unachievable before, for example the simulation of a viscous friction force F of the type F = Q * dx/dt, where the coefficient Q is for example a function of x and/ or dx/dt and/ or of time and/ or of Ern (for example as high as the user excesses the set speed or reference force), and it can change independently along x in both directions of the movement range.

The signal x may contain, or even just consist of, a signal containing information on the physical condition of the user, in particular during the exercise with the machine 50. In this context for example x could be

- a signal taken on the user's body to measure a physiological parameter or the muscular effort, for example a heart rate monitor or a thermometer;

- an inertial sensor placed on the user and/or on the resistance element transmitting for example data of movement to unit 70 in wireless mode, or

- a pedometer.

Then the response of the resistance element can be programmed and/or adapted to the current physical condition of the athlete.

Another variant for the signal x is that it includes, or also just consists of, the signal E inside the bock or system 82. Then the response of the resistance element can be programmed depending on and/ or adapted to the variance between the force applied on the element 58 and the force actually applied by the user.

The same signal variation described above for x, for example the formula (C), can be applied to these variants, keeping the advantages of increasing the number of responses that can be obtained from the machine 50 and/ or of the exercises that can be performed by the athlete.

For the variants described, the signal x thus defined can be calculated even without using the formula (C), but rather by using a general mathematical model calculated with unit 72.

The advantage of adapting the dynamic behavior of the machine 50 to the instantaneous physiology of the user or to the deviation from the set program remains.

The coefficients ai and F0 can be displayed, for example in a graph with single or multiple variable according to the customer's choice, on the display 66.

The programming of the parameters ai and/ or Fo can be carried out from the menu on the display 66.

Fig- 3 shows an example of machine in which the Mot engine drives a resistance element 98 in the two directions of the movement range. Here the element 98 is a swinging arm with two sleeves, arm or leg should be put in between them. Both in the extension and in the bending phase the limb is subject to the resistance controlled by the Mot engine.

It is also possible to program a unit 70, preferably also associating or integrating it with the elements 66, 68, to create an independent module which can be applied to a preexisting system 82 or machine, so that a known machine can be improved with the new exercise methodologies that can be obtained with the strategy described here. The module only requires the connection of the input line 62 and the output line 90.

The digital processing of the signal can be carried out with known programming techniques.

Claims

1. Method to control in feedback a resistance element (58) belonging to a machine (50) for physical exercise that can be moved by a user with muscular force in a certain movement range,

wherein a predefined reference resistance response (Fref), which can vary according to the movement range, is given to the element by means of a drive (60),

wherein a signal (x) indicating the position of the element within the movement range and/or the physiological condition of the user is acquired,

wherein a linear combination (C) of n-th derivatives, n>=0, of the indicative signal is calculated in order to obtain the reference resistance response,

wherein the coefficients (ai) of the linear combination have programmable values as a function of a variance (E) between a reference programmed response (Fref) and the actual response applied to the resistance element by the user.

2. Method according to claim 1 , wherein one or each of the coefficients have programmable values as a function of the indicative signal.

3. Method according to claim 1 or 2, wherein one or each of the coefficients have separately programmable values for each direction of the movement range.

4. Method according to claim 1 or 2 or 3, in which one and each of the coefficients has programmable values as a function of time.

5. Method according to one of the previous claims, wherein a variance (Erri) between at least one of the n-th derivatives and a reference (xref) for this derivative is calculated, and the reference resistance response (Fref) is calculated as a function of the variance.

6. Machine (50) for physical exercise with a resistance element

(58), movable by a user with muscular force in a certain movement range and controlled in feedback by means of a drive (60) which gives it a predefined reference resistance response (Fref) that can vary according to the movement range. It comprises

devices for measuring (60) a signal (x) indicating the element position within the movement range and/ or the current physiological data of the user,

devices to calculate (72) a linear combination (C) of n-th derivatives, n>=0, of the indicative signal to obtain the reference resistance response,

devices for programming (66, 72) in order to program the coefficients of the linear combination,

in which the devices for programming and/ or the devices for calculating are programmed or designed for allowing a programming of coefficients as a function of a variance between a reference programmed response and the actual response applied to the resistance element by the user.

7. Machine according to claim 6, in which the devices for programming and/ or the devices for calculating are programmed or designed for allowing a programming of the coefficients as a function of the indicative signal.

8. Machine according to claims 6 or 7, in which the devices for programming and/ or the devices for calculating are programmed or designed for allowing a programming of the coefficients as a function of a variance between at least one of the n-th derivatives and a reference for that derivative, and the reference resistance response is calculated as a function of the variance.

9. Machine according to one of the previous claims, in which the devices for programming and/ or the devices for calculating are programmed or designed for allowing a programming of all or some of the coefficients, as a function of the indicative signal.

10. Machine according to one of the previous claims, in which the devices for programming and/ or the devices for calculating are programmed or designed for allowing a programming of all or some of the coefficients separately for each direction of the movement range.

1 1. Machine according to one of the previous claims, in which the devices for programming and/ or the devices for calculating are programmed or designed for allowing a programming of all or some of the coefficients, as a function of time.

12. Accessory module which can be applied to a machine for physical exercise, comprising

an input line to acquire a signal indicating the position of the element within the movement range and/ or the current physiological data of the user,

devices or a circuit to calculate a linear combination of the n-th derivatives, n>=0, of the indicative signal to obtain a reference resistance response,

devices or a programming element to program the coefficients of the linear combination, and

an output line giving a signal containing the information of the reference resistance response calculated,

wherein the devices for programming and/ or the devices for calculating are programmed or designed for allowing a programming of the coefficients as a function of a variance between a programmed reference response and the response actually applied on the resistance element by the user.