FR3102579A1 - Periodic motion actuator, balancing equipment provided with such an actuator and method of operating such equipment - Google Patents

Abstract

The invention relates to a periodic motion actuator (20) for stable equilibrium swing equipment comprising: - an electric motor (22) for driving the actuator according to a periodic movement over a range of movement, - a control circuit (40) of a frequency of periodic movement, connected to the electric motor (22), and - a measurement circuit (82, 84) of the electrical energy consumption of the motor, The control circuit (40) is slaved to the circuit for measuring an electrical energy consumption (82, 84) of the electric motor (22) in order to adjust the frequency of the periodic movement to a value corresponding to a minimum electrical energy consumption of the electric motor (22). The invention also relates to balancing equipment (12) provided with such an actuator, and a method of controlling the equipment. Figure 3

Description

Periodic motion actuator, swinging equipment provided with such an actuator and method for driving such equipment

The present invention relates to a periodic motion actuator, a swing equipment provided with such an actuator, and a method for driving such equipment.

Swinging equipment is any equipment that can be used to swing or rock people or animals. Examples of such equipment include swings, rocking chairs, rocking seats, hammocks, cradles, rocking chairs, hanging chairs, prams with immobilized wheels and rocking seats for baby. More generally, it is equipment that can accommodate one or more people, or animals, and has a stable position of equilibrium. The stable equilibrium position is a position reached when the rocking motion is damped in the absence of equipment stress.

The invention finds applications for the manufacture of swinging equipment but also for the motorization a posteriori of existing swinging equipment.

State of the prior art

An illustration of the state of the art can be given, for example, by the following documents:
- US2010/0151951
- WO2014/058694
- WO98/08582

These documents describe swinging equipment, in particular swings and swings for children provided with an electric actuator. The equipment is provided with an electric motor actuator and a number of sensors and motor control means, so as to control the amplitude or phase of the swinging movement.

The aim of the invention is to provide an actuator, swinging equipment provided with the actuator, and a method for driving such equipment making it possible to maintain the equipment in an oscillatory movement capable of providing maximum well-being to the user. 'user.

The invention also aims to provide an actuator, swinging equipment provided with the actuator and a swinging body, and a method of driving such equipment to reduce the electrical energy consumed during operation.

Another object of the invention is to propose an actuator, and a simplified driving method, capable of being implemented either within the framework of the motorization of new balancing equipment or in the motorization a posteriori of existing equipment. .

Another object of the invention is to provide an actuator and a driving method that can be adapted to a very wide variety of swinging equipment.

To achieve these aims, the invention more specifically proposes a periodic motion actuator for a stable equilibrium swinging equipment comprising:
an electric motor for driving the actuator according to a periodic movement over a range of movement,
a periodic motion frequency control circuit, connected to the electric motor,
a circuit for measuring electrical energy consumption of the electric motor,
and in which:
the control circuit is slaved to the circuit for measuring electrical energy consumption of the electric motor to adjust the frequency of the periodic movement to a value corresponding to a minimum electrical energy consumption of the motor.

Unless otherwise specified, the term "periodic" is understood to encompass both periodic motions and pseudo-periodic motions. The periodic or pseudo-periodic character essentially depends on the transient or permanent regime of the oscillating movement.

Further, the term "periodic" is understood to encompass both elastic, gravity, elastic and gravity combined periodic motions, with or without significant friction.

The actuator can be one of a linear actuator, a rotary actuator, and a pendulum actuator. It can thus comprise one of a linear motor, a rotary motor and a pendulum motor. A linear motor is understood to mean an electric motor whose motion is rectilinear or a motor whose rotary motion is transformed into rectilinear motion by a mechanism such as a ball screw-nut mechanism, for example. A pendulum motor is understood to mean a motor provided with a rotor whose rotation is angularly limited to an arc of a circle of less than 360 degrees of angle, i.e. less than one complete turn. In the remainder of the description, pendulum motors and, by extension, pendulum actuators, are assimilated to rotary motors and actuators.

The motion of a rotary actuator is periodic in essence, with each complete revolution of the rotor or each revolution corresponding to a period. The range of movement of the actuator in this case is an angular range of 360 degrees of angle. As discussed below, an angular range of motion of less than 360 degrees is also contemplated. In the case of a pendular actuator, or a linear actuator, the periodic character of the movement can result from its piloting. In particular, a linear actuator can be driven to perform periodic reciprocating movements over a range of linear motion. A pendulum actuator can be driven to perform pendulum motion over an angular range less than 360 degrees of angle.

The control circuit has the particular function of fixing the frequency of the periodic movement likely to be exerted by the actuator on a swinging equipment. This frequency is proportional to the frequency of the periodic motion of the motor or the rotational speed of the motor. It is understood as a number of back and forth or back and forth movements per unit time for a linear or pendulum actuator, and as a number of revolutions per unit time for a rotary actuator.

The pilot circuit is connected to the motor. In particular, the control circuit may include an electric power supply for the electric motor. It can be one of a continuous power supply and a sequential power supply of the electric motor. In the case of a rotary actuator, the motor power supply can be continuous, and in the case of a linear or pendulum actuator, the power supply can be sequential. As opposed to the continuous power supply, which is applied continuously over the period of the movement of the actuator, by sequential power supply is meant an electrical power supply which is only applied to the motor over part of the period of its movement or a food whose characteristics change during the period of movement.

For a multi-phase synchronous rotary motor, for example a three-phase motor, the driver circuit can control the power supply supplying the currents of the different phases of the motor.

In the particular case of a rotary actuator, the frequency is simply related to the rotational speed of the motor. For a linear or pendular actuator, the control circuit can have a double function of causing a periodic back and forth movement and of fixing the frequency of this movement.

The electrical power supply of the motor may in particular be an energy storage power supply. By energy accumulator is meant an accumulator comprising one or more battery cells or an electric cell. The use of a mains power supply is also envisaged.

According to an important feature of the invention, the control circuit is slaved to the electrical energy consumption of the motor so as to adjust the frequency in a direction that reduces the electrical energy consumption. In other words, the control circuit is programmed to determine a minimum of electrical energy consumption as a function of frequency.

The minimum electrical energy consumption is reached when the swinging equipment, driven by its actuator, performs a periodic swinging movement at a frequency equal to, or at least very close to, its resonant frequency. At this frequency, the electrical energy consumed is essentially limited to energy losses due to friction and energy dissipation by Joule effect. Thus, in the rest of the description, the frequency of the periodic movement corresponding to the minimum consumption of electrical energy is also referred to as "resonance frequency".

The influence of the actuator itself on the resonant frequency, i.e. the frequency requiring the minimum operating energy, is minimal or zero. As such, it is neglected.

The electrical energy consumption can be determined by integrating the electrical power absorbed by the motor over one or more periods of oscillation. In the case of a constant or substantially constant voltage power supply, the energy consumption is proportional to the motor supply current. It suffices, in this case, to measure the electrical current consumed by the motor. It can be an instantaneous measurement or an average measurement over one or more periods. The frequency can then be adjusted so as to simply minimize the electric current supplying the motor.

Thus, the circuit for measuring electrical consumption of the motor may comprise one or more ammeters making it possible to measure the supply current of the motor or the supply currents of the various phases of the motor, a voltmeter making it possible to measure the voltage of power supply, and possibly one or more integrators making it possible to calculate an average current or an average power over one or more periods.

The control circuit may comprise an incremental control of the frequency of the periodic movement. The driver circuit is considered to include incremental control when it is capable of varying the frequency by a fixed amount constituting an increment or decrement depending on whether the frequency is increased or decreased. The frequency can then be adjusted iteratively in the process of finding the resonant frequency.

In general, the frequency of periodic movement of the actuator can be comprised in a range going, preferably, from 0.05 Hz to 5 Hz. The search for a frequency corresponding to a minimum electric consumption, can take place in this beach.

The actuator may also include range of motion control. Amplitude control means an interface allowing a user or a control circuit to adjust or modify the linear or angular amplitude of the movement or travel performed by the actuator. The purpose of this command is to allow a user to choose or control, in an induced manner, an amplitude of the swinging movement of the swinging equipment. Stroke control can be implemented for linear or pendulum actuators with adjustable stroke. The amplitude of the actuator stroke is defined over the range of movement of the actuator and can extend over all or part of this range. The range of motion is understood as the maximum amplitude of the actuator stroke.

It should be noted that the amplitude of the stroke of the actuator can be equal or simply proportional to that of the swinging equipment it drives. This aspect is further described below. The stroke amplitude control can be used particularly during transient start or stop phases of a rocking movement. The control of the amplitude of the stroke can be carried out autonomously with respect to the search for the resonance frequency, corresponding to the consumption of minimum electrical energy.

As mentioned above, the invention also relates to swinging equipment for people or animals, comprising a swinging body with stable balance, an actuator as described above, and a transmission connecting the swinging body to the actuator.

A swinging body means a moving part of the equipment on which one or more people, or animals, can sit. The swing body may comprise, for example, one of a hanging seat, a rocking seat, a rocking chair, a hanging seat, a rocking cradle, a swing, a garden swing, a swing chair and a hammock.

The swinging body is considered to be in stable equilibrium when, in the absence of stress, it ends up occupying a single determined position of equilibrium. In the case of a suspended seat, this is usually the lowest position. It should be noted that the stable balance position may vary slightly when one or more people have taken place on the swing body. As described below, the piloting of the actuator may include a setting on the position of stable equilibrium.

The sway body is connected to the actuator by a transmission, i.e. a device capable of transmitting all or part of the movement of the actuator to the sway body. The transmission may comprise, for example, one of a rigid link and a flexible link. A rigid link can include, for example, a bar, a connecting rod, a chain, and/or a gear train. In this case, the transmission is called "rigid". The rigid transmission makes it possible to transmit almost all the movement of the actuator to the swinging body. In other words, the rigid transmission allows the actuator to be coupled to the swing body over the full extent of its stroke, or range of motion.

The transmission may also include a flexible link. It is, for example, a rope or a strap, elastic or not. When provided with a flexible link, the transmission is said to be "flexible". It then only allows part of the movement of the actuator to be transmitted to the swinging body. More precisely, the transmission only makes it possible to couple, in this case, the actuator and the swinging body over a part of the range of movement or of the stroke of the actuator.

The reference to a rigid or flexible transmission does not prejudge the existence or not of an elastic component of the transmission.

The transmission may also include an amplitude amplifier. The amplitude amplifier has the effect of allowing or inducing movements of the swing body whose amplitude exceeds that of the stroke or the range of movement of the actuator. The amplitude amplifier can have a gear reduction or a simple pivoting lever arm. In the case of a pivoting lever arm, the actuator is connected to the lever arm at a closer distance from the pivot than the swing body.

The invention finally relates to a method for driving a swing equipment as described. The process includes:
a periodic motion frequency sweep over a range of frequencies,
the search, in the frequency range, for a frequency of the periodic movement minimizing an electrical consumption of the electric motor,
the control of the actuator for an actuation of the rocking body at the frequency of periodic movement minimizing the electrical consumption of the electric motor.

The control of the actuator with the frequency minimizing the electrical consumption of the motor, makes it possible to establish a steady state of swinging of the swinging body.

The search for a frequency of the periodic movement minimizing the electrical consumption of the electric motor of the actuator amounts to tuning the actuator to the resonance frequency of the swinging body. Even more precisely, this amounts to tuning the swinging equipment, which includes the actuator, the transmission and the swinging body, to its natural frequency or resonant frequency.

The search for the resonance frequency can take place in a limited frequency range corresponding, for example, to the predefined operating range of the actuator. This is, for example, the aforementioned range from 0.05 Hz to 5 Hz. The search for the resonance frequency can take place randomly, or, preferably by performing a sweep of the frequency range considered. The sweep can be, for example, a sweep at increasing frequencies, starting from the lowest frequency of the frequency range. In particular, the scanning of the periodic motion frequency and the search for a periodic motion frequency minimizing the electrical consumption of the electric motor can comprise the following steps:
a) the fixing of a low frequency of periodic movement, the low frequency, being part of the frequency range of the actuator, the measurement of an electrical consumption of the motor and the recording of the measurement as reference consumption,
b) the increase, in the frequency,
c) the measurement of a new electrical consumption of the motor,
d) comparison of the new electrical consumption of the motor with the reference consumption,
e) the increase in frequency, if the new electrical consumption of the motor is lower than the reference consumption,
f) the recording of the new electricity consumption as reference consumption,
g) iteration of steps c to f, until the measurement of a new electrical consumption of the motor greater than the reference consumption.

When the new electrical consumption of the motor becomes higher than the reference consumption, the resonant frequency has just been exceeded. It is then possible to establish a stationary oscillating movement at the frequency at which the reference consumption was measured.

Preferably , the increase in frequency can be operated in a fixed increment. This amounts to searching for the resonance frequency by iteration and by discrete values. The value of the increment determines in this case the smoothness or precision with which the resonant frequency is established.

Other methods of scanning the frequency range, for example a continuous scan, or a plurality of partial successive scans with increasing precision, can also be considered.

According to another feature of the invention, the method can be implemented for equipment provided with a motion amplitude control. In this case, the method may include a phase of incremental increase of an amplitude of the periodic movement to reach a setpoint amplitude. The setpoint can be preset or programmable by a user of the equipment. The amplitude of the periodic movement is understood as the amplitude of the stroke of the actuator over its range of movement. Due to transmission it can also be related to an amplitude of body sway.

The incremental and progressive increase in the amplitude of the movement and its frequency makes it possible to reach the resonance frequency and the set amplitude with maximum comfort for the user.

It should be noted that the incremental and gradual increase in the amplitude of the movement can take place, before the search for the resonant frequency, after having searched for the resonant frequency, alternately with the search for the resonant frequency or concomitantly with the search for the resonant frequency.

Advantageously, the method may include a preliminary phase of determining whether the transmission is a flexible link transmission or a rigid link transmission, the determination comprising a comparison of traction currents and thrust currents of the actuator during the movement periodic, the pulling and pushing currents being measured on distinct alternations of the periodic movement of the actuator.

It is considered that the transmission is rigid, that is to say with rigid link, when the movement of the actuator and the movement of the swinging body are linked over the whole of a period or a stroke of the movement periodic. Conversely, it is considered that the transmission is flexible, that is to say with flexible link, when the movement of the actuator and the movement of the rocking body are linked over only part of a period or of the stroke of the periodic motion.

By course of the periodic motion is meant the part of the motion which is reproduced equal to itself during each period. The stroke can be the range of motion of the actuator or part of the range of motion of the actuator.

By alternation we mean part of the movement taking place in the same direction in the case of a back and forth movement, or back and forth of a linear or pendular actuator. In the case of a rotary movement, an alternation is considered as a half turn. Typically the stroke of the actuator has two alternations and a midpoint separating the two alternations. The midpoint can be a point of reversal of the direction of travel in a back and forth movement.

As the movement of the actuator is linked to that of the swinging body, the terms of period, alternation and travel, defined for the actuator, are understood as also qualifying the movement of the swinging body, unless otherwise specified.

Traction and/or thrust currents absorbed by the electric motor of the actuator can be measured on distinct alternations of the periodic movement of the actuator. As indicated above, for a linear actuator, the two alternations can correspond to the outward and return movement of a back and forth type movement within the range of movement of the actuator. The pulling and pushing currents are thus understood as currents measured during a pulling and pushing phase, respectively.

The traction current, as well as the thrust current can be understood either as maximum power supply currents absorbed by the actuator respectively on the considered alternation, or as average currents on the considered alternation.

When the traction current and the thrust current are of identical amplitude or at least of the same order of magnitude, the traction is considered to be rigid. The actuator works in traction and in thrust, and its movement is transmitted to the rocking body over the two alternations of a period of the periodic movement.

When, on the other hand, one of the traction current and the thrust current is very low compared to the other of the traction current and the thrust current, the transmission is considered to be a flexible transmission. This is, for example, a rope or a strap that pulls the swinging body on one of the alternations and is loose on the other alternation of the period of the periodic movement.

In the case of a flexible transmission, the current on one of the alternations or on part of one of the alternations is typically equal to the no-load current of the actuator, that is to say equal to the current consumed in the lack of load.

In the case of swinging equipment comprising an actuator with an adjustable stroke midpoint, the method may include a phase for adjusting the midpoint of the stroke of the actuator to a rest position of the swinging body. The position of rest corresponds to the position of stable equilibrium.

The actuator is considered to have an adjustable midpoint of travel when the point of reversal of direction of motion or a midpoint of actuator travel can be moved through the range of motion of the actuator. In the case of a linear actuator, the midpoint preferably corresponds to the point of reversal of the direction of movement. In the case of a rotary actuator, the midpoint is considered to be the position of the actuator coinciding with the swing body in the equilibrium position. In the case of an electric actuator, the adjustment of the midpoint can take place via the pilot circuit of the actuator.

When the swinging equipment includes a rigid transmission, the adjustment phase may include measuring the thrust and traction electrical supply currents of the actuator during the traction and/or thrust phases during the periodic movement, and moving the midpoint of the actuator stroke in a direction that reduces a gap between the push and pull supply current.

The adjustment phase ends when the pushing current is equal to the pulling current or when the difference between the pushing and pulling current is less than a defined value. The pushing current and the pulling current are understood either as instantaneous currents or as average currents over the pulling and pushing phases of the periodic motion.

When the maximum motor power is insufficient to balance the pulling and pushing currents, or to reach the resonance frequency, a signal can be emitted to prompt the user to manually adjust the transmission between the actuator and the swing body. Such an operation may be necessary when an actuator is associated with a rocking body which was initially devoid of it.

In the case where the swinging equipment comprises a flexible transmission, the adjustment phase of the midpoint of the stroke of the actuator may comprise the determination of a position of the range of movement of the actuator from which a Actuator supply current exceeds no-load supply current and moving the midpoint of actuator travel to that position.

The no-load supply current is the current drawn by the moving actuator when it is not driving any load. This current is established on a part of the travel of the actuator in which the flexible transmission is released and does not exert a force on the swinging body. On the other hand, the current increases suddenly as soon as the flexible transmission transmits the movement of the actuator to the swinging body.

When the actuator supply current remains equal to the no-load supply current throughout the actuator's range of motion, a signal can also be output to warn the user that the transmission is too loose.

The method may also include the control of the actuator according to different speed profiles and the search for a speed profile that minimizes the electrical consumption of the motor. By speed profile, we mean a curve of the evolution of the speed of the actuator with respect to time. Whatever the equipment, this curve is never a straight line since the speed is almost zero near the points of reversal of direction and is maximum when passing the midpoint. A velocity profile for equipment with purely elastic motion can be, for example, a pure sinusoid. The speed profile can be adapted in particular when the rocking movement involves significant friction, elastic restoring forces or elastic restoring torques.

Other characteristics and advantages of the invention emerge from the following description with reference to the figures of the drawings. This description is given for illustrative and non-limiting purposes.

Brief description of figures

Figure 1 is a schematic representation of a balancing equipment according to the invention provided with a rotary actuator and a rigid transmission, with a non-adjustable amplitude.

Figure 2 is a schematic representation of a balancing equipment according to the invention provided with a linear actuator, an amplitude amplifier, and a flexible transmission.

Figure 3 is a schematic representation of swing equipment showing an equipment actuator and an actuator drive circuit.

Figure 4 is a flowchart illustrating an example of implementation of an equipment control method.

FIG. 5 is a more detailed flowchart illustrating improvements to the driving method.

Figure 6 is a graphical representation of a first velocity profile for the swing equipment.

Figure 7 is a graphical representation of a second velocity profile for the swing equipment.

The figures are represented in free scale

Detailed description of embodiments of the invention

In the following description, identical, similar or equivalent parts of the various figures are marked with the same reference signs so as to be able to refer from one figure to another.

Figure 1 shows swinging equipment 10 provided with a swinging body 12 in the form of a rocking chair 12a. For simplicity, the various parts of the equipment and in particular the rocking chair are not represented according to a uniform scale.

The rocking chair has a stable equilibrium position which is the position occupied in the absence of stress. The stable equilibrium position is represented by a dashed line.

The equipment also includes an actuator 20 to cause periodic swinging of the swinging body. In the example of Figure 1 the actuator comprises an electric motor 22, represented symbolically in broken lines. It has an output shaft with a pulley 24. The actuator is a rotary actuator with a rotary motor. Pulley 24 drives a crank wheel 26 via a belt. Finally, the crank wheel 26 is connected to the swing body 12 by a connecting rod 28. One end of the connecting rod 28 is pivotally mounted on a crank pin of the crank wheel 26, while the opposite end of the connecting rod is mounted pivoting on the rocking body, that is to say on the rocking chair 12a.

The crank wheel 26 and the connecting rod 28 constitute a transmission 30 connecting the swinging body 12 to the actuator 20. This is a rigid transmission, or rigid link. The rigid nature of the transmission results in the fact that the movement of the actuator and the movement of the rocker body are linked over an entire period of the movement.

In the case of the example described with reference to Figure 1, the crank wheel 26 constitutes a motion amplifier. It is considered that the period of the rocking movement corresponds here to a complete round trip of the rocking chair and to a rotation of 360 degrees of angle of the crank wheel 26. The period of the movement corresponds in this case to several rotations of the pulley 24.

A control circuit 40 of the actuator 20 is shown in broken lines. It makes it possible to modify the speed of rotation of the motor 22 and thus to change the frequency of the periodic movement, that is to say the frequency of tilting of the rocking chair 12a. The frequency is proportional to the speed of rotation.

Figure 2 illustrates another possible implementation of the invention for the actuation of a swing. The rocking body 12 here comprises a suspended seat 12b. An actuator 20 is mounted on a support 50. It is a linear actuator in the form of an electric cylinder comprising a motor 22. The electric cylinder has an arm 52 capable of performing periodic back and forth movements by extending out of the cylinder body and retracting inside the cylinder body. The cylinder stroke is considered to have two alternations corresponding respectively to the extension and retraction of the arm 52. This periodic movement is used to drive the swinging body 12.

Arm 52 of actuator 20 is pivotally mounted on a lever 54 remote from its ends. A first end of the lever 54 is articulated on the support 50 while a second free end of the lever, opposite the first end, is connected to the rocking body 12 via a strap 58. The lever 54 constitutes a motion enhancer.

A transmission 30 between the actuator and the swinging body comprises the lever 54 and the strap 58. The strap, or possibly a cord replacing the strap, are flexible. Also the transmission 30 is here a flexible transmission. This results in the fact that only a part of the movement of the actuator is transmitted to the rocking body.

More precisely, when the arm 52 of the actuator extends out of the cylinder body, the lever 54 pivots in the direction of the swing body. During this movement the strap is not stretched and no force is transmitted to the swinging body 12. The swinging body 12 can then swing freely away from the actuator as shown in FIG. . Conversely, when the arm of the actuator enters the cylinder body, the strap becomes taut and pulls the swing body 12 in the direction of the cylinder. This alternation of movement is represented by a broken line. In the rest of the description it is referred to as "traction alternation" as opposed to "free alternation" in which the strap is not taut.

The actuator is provided with a control circuit indicated symbolically with the reference 40. It makes it possible to control the operation of the actuator 20. More precisely, the control circuit makes it possible:
- to cause the periodic back and forth movement of the actuator, that is to say of the cylinder arm,
- to adjust the frequency of the movement,
- to adjust the amplitude of the movement, that is to say the amplitude of a stroke 60 of the actuator, and more precisely of the arm 52 of the cylinder over a range of movement 62 of the cylinder,
- To adjust, on the range of movement 62, a midpoint 64 of the stroke 60 of the actuator separating the two alternations of the stroke.
Incidentally, the control circuit can also be used for:
- detect the type of connection, flexible or rigid
- apply a periodic movement according to several speed profiles.

A simplified control circuit can also be selected so as to control only part of the aforementioned parameters.

The control of certain operating parameters can take user commands into account. In the example of Figure 2 a remote control interface 42 is linked to the control circuit 40 so as to allow a user to enter, for example the amplitude of the movement, and therefore the amplitude of the swing in steady state . Remote 42 is part of a range of motion control.

In Figure 2, actuator stroke 60, range of motion 62, and midpoint 64 are shown symbolically. The midpoint 64 of the stroke 60 of the actuator is the point equidistant between the positions that the end of the arm 52 of the actuator 20 occupies at the limits of the stroke 60 of the actuator 20, i.e. say when the arm is fully extended or fully retracted. The midpoint 64 preferably also corresponds to the middle of the range of motion 62.

The midpoint 64 can be adjusted, for example, to correspond to the equilibrium position of the swing body 12, i.e. when the suspended seat 12b is in its lowest position.

The maximum amplitude of the rocking motion is achieved when the 60 stroke of the actuator is set to the maximum to be equal to the range of motion 62 of the actuator, i.e. the maximum stroke of the actuator or cylinder constituting the actuator.

While performing periodic motion, the actuator 20 does not necessarily exhibit a constant motion speed over a period. For example, a higher movement speed of the arm can be provided during the free alternation, so as not to risk hindering the swinging movement, while a lower movement speed can be provided during the alternation. of traction.

It should be clarified that a particular type of actuator is not tied to a particular type of swing body. The actuators 20 of the equipment of FIGS. 1 and 2 are interchangeable.

Figure 3 schematically shows an equipment according to the invention as well as the main organs forming part of the control circuit 40 of the actuator.

The control circuit 40 connects the motor 22 of the actuator to a power supply source 70. In the example of FIG. 3, the power supply source is an accumulator battery. Power supply by electric batteries or power supply by an energy distribution network is also possible.

Power source 70 is connected to motor 22 of actuator 20 via motor power circuit 80. The power supply circuit 80 is built around power transistors and makes it possible to switch the currents supplied to the various phases of the motor 22. The power supply circuit 80 makes it possible to control the speed of rotation or actuation of the motor, the direction of rotation or actuation, as well as the range of motion of the actuator 20.

The control circuit 40 comprises a member 82 for measuring the current absorbed from the energy supply source, or possibly a member for measuring the current. In the example of FIG. 2, the measuring device 82 is an ammeter 82 in series with the power supply source 70. According to another possible embodiment of the control circuit, it is also possible to directly measure the current supplied to the different phases of the motor.

Driver circuit 40 may also include a voltmeter (not shown) to measure the voltage across power source 70.

The information corresponding to the current measurement is supplied to a computer 84, associated among other things with a memory 86 and a comparator 88. As emerges in more detail from the following description, the comparator 88 makes it possible to compare either instantaneous currents or average currents, the average of which is established over one or more periods or over part of a period of the movement. The comparison can take place with current values measured and stored during previous measurement cycles.

The memory 86 makes it possible to store information such as maximum current values, minimum current values, or previously established average current values.

Incidentally, the memory can also be used to store previously calculated energy values, positions of the actuator, speed profiles, and more generally data used by the computer 84.

As mentioned above, the control unit 40 can be provided with a control interface 42, also connected to the computer 84 by radio or wire.

From the measured current data, and their comparison with stored data, as well as from any commands entered on the command interface 42, the computer 84 establishes switching states for the power transistors of the circuit of engine control 80.

Figure 4 is a graphic representation of an important characteristic of the method of driving the equipment of the invention, according to which the frequency is sought which minimizes the electrical consumption of the motor 22.

The minimum consumption frequency, which corresponds to the resonance frequency already mentioned, is sought in a range of operating frequencies 102 of the actuator. This frequency can be understood as the frequency of a round trip movement of a linear actuator or the number of revolutions per second for a rotary actuator. When the movement is not geared down or reduced, it is also the swing frequency of the swing body.

The frequency range includes a minimum frequency denoted Fmin and a maximum frequency denoted Fmax. The search for the resonance frequency can take place by a sweep 100 of the frequency range 102, for example from the minimum frequency to the maximum frequency. Non-linear scans can also be considered.

The sweep 100 of the frequencies may take place in fixed increments 110 of the frequency. The resonant frequency is thus approximated by discrete values.

For a given frequency Fn, the electrical consumption of the actuator P(Fn) is measured. The electrical consumption can be expressed, for example, in the form of the power consumed, or more simply of an integration of the electrical current consumed over all or part of a period, or over several periods of the swing. In the case of a power consumption, the current can be multiplied by the supply voltage of the actuator.

During a comparison step 108, the electrical power P(Fn) consumed for the frequency Fn is compared with the electrical power consumed P(Fn-1) calculated for a previous frequency Fn-1.

In the case of a sweep in increasing frequencies, if the consumption P(Fn) is lower than the consumption P(Fn-1) then the operation is iterated with the frequency Fn+1, and by comparing the consumption P(Fn +1) to consumption P(Fn). The iteration is continued as long as the power consumption decreases with the increase in frequency. The increase in frequency is carried out in constant value increments.

On the other hand, if the consumption P(Fn) becomes greater than the consumption P(Fn-1) this supposes that the minimum was reached with the frequency Fn-1. The control circuit 80 is then controlled in stationary mode to control a frequency of the periodic movement equal to the frequency F(n-1) closest to resonance.

Figure 5 shows in the form of a flowchart the main operations or steps that can be implemented during the method of operating equipment in accordance with the invention and indicates a certain number of improvements.

A first step is an initialization step 210. During this step the actuator is driven to occupy a reference position, for example a mid-position for a linear actuator.

During the initialization step, the operating parameters or setpoints are also read by the computer 84. The operating parameters may comprise a setpoint amplitude entered by the user, a starting amplitude, a speed a starting frequency, for example the minimum frequency, a stop delay and an automatic stop mode. All of this data can be stored in a memory of the computer 84.

A next step is a test step 220 of the transmission. It includes supplying the engine with a view to stressing the transmission. It is accompanied by a measurement of the electric current supplied to the electric motor. As soon as the current becomes greater than the no-load current, the transmission is considered to act on the swinging body. In the case of a flexible connection, this phase makes it possible to tension the transmission and in particular a strap or a rope forming part of the transmission. If the current becomes higher than the no-load current before the actuator has reached its end of travel, or has completed a full rotation, a next step can be initiated. This means in effect that the transmission 30 has been energized or stressed and that the actuator 20 has been loaded. On the other hand, if the current remains equal to the no-load current, it is possible that the transmission 30 is not connected to the actuator 20 or that the transmission 30 is too loose. A stop is then caused and a fault signal is emitted.

A next step is a step 230 of detecting the type of transmission. This step consists of determining whether the transmission is a rigid link transmission or a flexible link transmission. It consists of successively performing a movement on one alternation of the actuator, for example a pull, then a movement on the other alternation, for example a push. During the two movements, a minimum current and a maximum current are recorded, namely a minimum and maximum thrust current and a minimum and maximum traction current. The value of the minimum current is close to or equal to the no-load current.

If none of the currents exceeds the minimum value, this means that the movement of the actuator 20 is not transmitted to the swinging body 12. Operation is then interrupted and a fault signal is issued.

If at least one of the traction and thrust currents exceeds the no-load value, a comparison 232 of the traction and thrust currents is performed. If the maximum thrust current is much higher than the traction current, or if the traction current is much higher than the thrust current, the driving of the equipment is continued according to a 240a driving mode for flexible link transmission.

Conversely, if the traction current is close to the thrust current, the operation of the equipment is continued according to a 240b mode for rigid link transmission. In the rest of the description, the corresponding steps of the two modes are marked with the same references to which the letter a is added when the transmission is determined as flexible and the letter b when the transmission is determined as rigid.

A first step 242a, 242b following the determination of the type of transmission is a so-called "setting" step which consists in setting the stroke 60 of the actuator 20 on the stable equilibrium position of the swinging body 12.

When the transmission is flexible, the wedging step 242a consists in carrying out a certain number of pulls, that is to say actuation on an alternation of the actuator with a free return of the rocking body 12. the position of the actuator from which the current absorbed by the motor exceeds the no-load current. The actuator stroke is then offset so that this position coincides with the midpoint 60 of the stroke. This operation can be performed iteratively and incrementally over several periods of the movement.

When the transmission is rigid, the step of setting 242b consists of performing a certain number of pulls and pushes and determining the maximum push and pull currents. The stroke 60 of the actuator is then adjusted iteratively and incrementally until the maximum thrust current and the maximum traction current are substantially equal, or at least a difference between the traction current and the thrust current is reduced.

A following step is a step 244a, 244b of searching for a frequency minimizing the consumption of energy or electric current. This step, which consists of finding the resonance frequency of the equipment, is identical regardless of the type of transmission, flexible or rigid. This is the step already described with reference to Figure 4. The search for the resonance frequency can be accompanied by a gradual increase in the amplitude of the rocking movement, until reaching a predetermined set value. or a value entered by the user.

The step of searching for a resonant frequency is followed by a step 246a, 246b of searching for an optimized oscillation speed profile. During this step, it is possible to successively apply and evaluate a certain number of memorized speed profiles. This consists of controlling the electric motor of the actuator according to the different speed profiles and measuring the energy consumed over one or more periods of movement for each speed profile. The velocity profile that requires the minimum energy can then be retained for the periodic rocking motion in the steady state. According to an improvement, a search for the resonance frequency can be carried out for each speed profile tested.

By way of illustration, Figures 6 and 7 show, in the form of graphs, two speed profiles likely to be tested and evaluated for swinging equipment. They correspond to the control of a linear actuator. The graphs indicate the ordinate of the movement speed of the actuator.

The graphs in Figures 6 and 7 indicate on the ordinate a linear displacement speed of the actuator as a function of the position of the arm of the actuator in its stroke. The position is indicated on the abscissa. The positive or negative values of the speed correspond respectively to two successive alternations of the movement (round trip).

The comparison of the graphs of FIGS. 6 and 7 shows slight differences in the speed profiles, the general shape of which nevertheless remains of the sinusoidal type. Finally, a last step consists in maintaining the rocking movement in stationary mode 248a, 248b. When the transmission is flexible, this consists in carrying out a traction on each period followed by a free return of the swinging body 12. The traction and the free return are carried out at the resonance frequency and according to the previously determined oscillation profile. In the case of a flexible transmission, the return movement has a slightly less amplitude than that of the traction movement to take into account the natural slowing down of the movement due to friction.

When the transmission is rigid, the steady state comprises for each period a push and a pull applied to the swinging body 12 by the actuator 20 with the resonance frequency and according to the determined oscillation profile.

The stationary regime can be timed so as to interrupt the actuation of the swing body after a predetermined or user-selected time. A soft stop can be achieved by gradually reducing the range of motion of the actuator. An emergency stop procedure is also possible.

Claims (20)

1) Periodic motion actuator (20) for stable equilibrium balancing equipment comprising:

• an electric motor (22) for driving the actuator according to a periodic movement over a range of movement (62),
• a control circuit (40) of a frequency of the periodic movement, connected to the electric motor (22),
• a circuit (82, 84) for measuring electrical energy consumption of the motor,

in which :
the control circuit (40) is slaved to the electrical energy consumption measurement circuit (82, 84) of the electric motor (22) to adjust the frequency of the periodic movement to a value corresponding to a minimum electrical energy consumption of the electric motor (22). 2) An actuator according to claim 1, wherein the actuator (20) is one of a linear actuator, a rotary actuator, and a pendular actuator. 3) Actuator according to any one of claims 1 or 2, wherein the control circuit (40) comprises an incremental control of the frequency of the periodic movement. 4) Actuator according to any one of the preceding claims, in which the periodic movement frequency is within a range from 0.05 Hz to 5 Hz. 5) Actuator according to any one of the preceding claims, wherein the control circuit (40) comprises a power supply (70, 80) of the electric motor (22). 6) Actuator according to claim 5, wherein the power supply (70, 80) is an energy storage power supply (70). 7) Actuator according to any one of the preceding claims comprising a control (42) of amplitude of movement. 8) Swinging equipment comprising a swinging body (12) with stable equilibrium, an actuator (20) according to any one of the preceding claims, and a transmission (30) connecting the swinging body to the actuator. 9) Equipment according to claim 8, wherein the transmission (30) comprises an amplitude amplifier (26, 54). 10) Equipment according to any one of claims 8 or 9, wherein the transmission (30) comprises one of a rigid link (28), and a flexible link (58). 11) Swinging equipment according to any one of claims 8 to 10, wherein the swinging body (12) comprises one of a suspension seat (12b), a rocking seat (12a), a rocking chair, a suspended seat, a rocking cradle, a swing, a garden swing, a swing and a hammock. 12) A method of driving equipment according to any one of claims 8 to 11, comprising:

• a periodic motion frequency sweep (100) over a frequency range (102),
• the search, in the frequency range, for a frequency (Fn) of the periodic movement minimizing an electrical consumption of the electric motor,
• the piloting of the actuator (20) for an actuation of the rocking body the frequency of periodic movement minimizing the electric consumption of the electric motor.

13) Method according to claim 12, in which the scanning of the periodic motion frequency and the search for a periodic motion frequency minimizing the electrical consumption of the electric motor comprises the following steps:
a) setting a low frequency (Fmin) of periodic movement, the low frequency, being part of the frequency range (102) of the actuator, measuring an electrical consumption of the motor and recording the measurement as reference consumption (P(Fn-1)),
b) the increase, in the frequency,
c) the measurement of a new electrical consumption of the motor (P(Fn)),
d) the comparison (108) of the new electrical consumption of the motor (P(Fn)) with the reference consumption (P(Fn-1))
e) the increase in frequency, if the new electrical consumption of the motor is lower than the reference consumption,
f) the recording of the new electrical consumption (P(Fn)) as reference consumption,
g) iteration of steps c to f, until the measurement of a new electrical consumption of the motor greater than the reference consumption. 14) Method according to any one of claims 12 and 13, in which the increase in frequency is carried out according to a fixed increment (110). 15) Method according to any one of claims 12 to 14, for equipment provided with an amplitude of movement control (42), comprising a phase of incremental increase of an amplitude of the periodic movement to reach an amplitude of order. 16) Method according to any one of claims 12 to 15, comprising a preliminary phase of determining (230) whether the transmission (30) is a flexible link transmission (58) or a rigid link transmission (28), the determination comprising a comparison of traction currents and of thrust currents of the actuator during the periodic movement, the traction and thrust currents being measured on distinct alternations of the periodic movement of the actuator. 17) Method according to any one of claims 12 to 16, for a balancing equipment comprising an actuator with an adjustable stroke midpoint (60), comprising a phase (242a, 242b) for adjusting the midpoint (60) of the stroke of the actuator (20), on a rest position of the rocking body (12). 18) A method according to claims 16 and 17, for swing equipment (10) comprising a rigid transmission (28, 30), wherein the step of adjusting the midpoint (64) comprises, measuring the electrical supply currents pushing and pulling of the actuator during pulling and/or pushing phases during the periodic movement, and the displacement of the midpoint (64) of the stroke (60) of the actuator (20), in one direction reducing a gap between the pushing and pulling current. 19) A method according to claims 16 and 17, for swing equipment (10) comprising a flexible transmission (30, 58), wherein the step of adjusting the midpoint comprises determining a position of the range of movement of the actuator from which an actuator supply current exceeds a no-load supply current, and moving the midpoint (64) of the stroke (60) of the actuator (60) toward this position. 20) Method according to any one of claims 12 to 17, comprising controlling the actuator according to different speed profiles, and searching (246a, 246b) for a speed profile that minimizes the electrical consumption of the motor.