FR3084291A1 - VEHICLE DAMPING DEVICE AND ASSOCIATED METHOD - Google Patents

Abstract

The invention relates to a damping device (20) of a vehicle comprising a semi-active damper (22) and an associated control device (24) comprising: - an accelerometer (26) capable of measuring the transverse acceleration of the vehicle; - a control unit (28) configured to determine a setpoint effort to be made by the damper (22) from the acceleration signal (S1) in order to minimize the transverse oscillations of the vehicle; - a control unit (30) of the shock absorber (22) as a function of the force signal (S2); - a detector (32) of movement of the shock absorber (22); - a modeling unit (34) configured to determine a state variable characteristic of the movement of the shock absorber (22) by means of a theoretical model of the shock absorber (22) and of the control signals (S3) and of displacement (S4). The control unit (30) is able to determine the control signal (S3) also from the status signal (S5).

Description

Vehicle damping device and associated method

The present invention relates to a device for damping a vehicle, especially a rail vehicle, comprising a semi-active damper and a control device configured to control the semi-active damper, the control device comprising an accelerometer capable of measuring the transverse acceleration of the vehicle and transmitting an acceleration signal comprising the measurement of the transverse acceleration; a control unit configured to receive the acceleration signal, determine a setpoint force to be produced by the semi-active damper from the acceleration signal in order to minimize the transverse oscillations of the vehicle and transmit a force signal comprising the setpoint effort and a control unit configured to receive the effort signal, and transmit a control signal, as a function of the effort signal, to the semi-active damper.

The damping device is in particular intended to solve the problems of transverse vibrations in a railway vehicle traveling at high speed. In order to improve passenger comfort and for safety reasons, it is important to greatly reduce these transverse vibrations.

To this end, it is known to use semi-active dampers constituting a good compromise between damping performance and energy and material cost. We speak of a semi-active damper when the damper has variable characteristics controlled without providing significant power.

In particular, a semi-active damper is known, controlled by a control circuit composed of an inverse model of the damper, the inverse model determining a value of the control current of the damper from a value of relative speed. between two ends of the damper and a force setpoint. Such a shock absorber is for example described in the document EP 0 816 141.

However, this shock absorber is not entirely satisfactory because its control is not optimized and does not take into account all the possible behaviors of the shock absorber.

An object of the invention is to obtain a semi-active damper whose control is improved.

To this end, the subject of the invention is a damping device of the aforementioned type, characterized in that the control device also comprises a displacement detector capable of measuring the displacement of the semi-active damper and transmitting a signal displacement comprising the displacement measurement and a modeling unit configured to receive the control signal and the displacement signal, determining a state variable characteristic of the displacement of the semi-active damper by means of a theoretical model of the semi-active damper and control and displacement signals and transmit a status signal comprising the characteristic state variable to the control unit, the control unit being able to determine the control signal also from the status signal.

The modeling unit makes it possible, thanks to the theoretical model, to provide the control unit with information on the state of the semi-active damper taking account of the internal rigidities in said semi-active damper and thus providing a more accurate estimate. fine of the force exerted by the shock absorber and in particular the effective orientation of the latter. The control unit thus corrects the control current to be sent to the semi-active damper using this information. The invention therefore allows control of the semi-active damper optimized in the sense that the control current applied to the semi-active damper takes account of the hysteretic behavior of the semiactive damper. The hysteretic behavior of the shock absorber is linked to the internal stiffnesses of the shock absorber as well as to the stiffnesses of attachment (joints, cups or others) which lead to phase shifts between the damping force and the speed of movement of the shock absorber attachment points on the vehicle. If this offset is not taken into account, it can lead, in certain configurations, to a real force in the opposite direction to the desired control force and thus make the damper control not optimal.

The damping device may include one or more of the following characteristics, taken in isolation or in any technically possible combination:

- the theoretical model is a Maxwell model comprising an ideal damper in series with an ideal spring;

- the modeling unit is able to determine the damping coefficient of the ideal damper from experimental measurements of the force produced by an experimental damper, analogous to the semi-active damper;

- the characteristic state variable is the relative speed of movement of the ends of the ideal damper;

- the damping device comprises a bandpass filter configured to filter the acceleration signal at the output of the accelerometer;

- the bandpass filter is configured to let the frequencies pass substantially between 0.25 Hz and 1.5 Hz and attenuate the rest of the frequencies;

the control unit is configured to use a hybrid control algorithm, the hybrid control algorithm being composed of an "Acceleration Driven Damping Control" type algorithm associated with a "Skyhook" type algorithm;

- the bandpass filter is a second order filter with infinite impulse response and in which the control unit is configured for:

+ apply the "Acceleration Driven Damping Control" type algorithm to signals with a frequency below 0.5 Hz, + apply the "Skyhook" type algorithm to signals with a frequency above 5 Hz, + apply in a hybrid way, the “Acceleration Driven Damping Control” type algorithm with the “Skyhook” type algorithm with signals having a frequency between 0.5 Hz and 5 Hz, with a gradual increase in weight the type algorithm "Skyhook" with frequency.

The subject of the invention is also a method for controlling a semi-active damper comprising the following steps:

- measurement of the vehicle's transverse acceleration and transmission of the acceleration signal by the accelerometer;

- reception of the acceleration signal, determination of the target effort and transmission of the effort signal by the control unit;

- reception of the force signal and transmission of the control signal to the semi-active damper by the control unit;

- measurement of the displacement of the semi-active damper and transmission of the displacement signal by the detector;

- reception of the displacement signal, determination of the characteristic state variable and transmission of the state signal by the modeling unit; and

- reception of the state signal, determination of the control signal also from the state signal and transmission of the control signal to the semiactive damper by the control unit.

The invention will be better understood on reading the description which follows, given solely by way of example, and made with reference to the appended drawings, in which:

- Figure 1 is a schematic sectional view of a vehicle, in particular rail, equipped with a damping device according to the invention;

- Figure 2 is a schematic representation of a Maxwell model constituting a variant of the mechanical model used for the modeling of a semi-active damper in a damping device according to the invention;

- Figure 3 is a flow diagram of a control method according to the invention;

- Figure 4 is a flow diagram of a variant of the control method according to the invention on the basis of a simple mechanical modeling of the damper by a Maxwell damper;

- Figure 5 is a Bode diagram of the bandpass filter 36.

A rail vehicle 10 shown in Figure 1 is for example a train car carrying passengers.

The rail vehicle 10 conventionally comprises a body 12, seats 14, a bogie 16 provided with wheels 18 and at least one damping device 20.

The seats 14 are located in the body 12 and allow passengers to sit during transport.

The bogie 16 is located under the body 12. The body 12 is suspended on the bogie 16, that is to say that the damping device 20 is interposed between the bogie 16 and the body 12 so that the body 12 can move relative to the bogie 16.

The wheels 18 are fixed to the bogie 16 by axles not shown in the figures. The wheels 18 are configured to roll on rails 21 and thus allow the movement of the rail vehicle 10.

The damping device 20 comprises a semi-active damper 22 and a control device 24.

The semi-active damper 22 connects the body 12 and the bogie 16. The semi-active damper 22 is configured to dampen the transverse oscillations of the body 12 in order to improve the comfort of the travelers present in the body 12.

The behavior of the semi-active damper 22 is satisfactorily approximated by a Maxwell damper or any other suitable rheological model (Spencer, Bouc-Wen, Dahl, LuGre, hyperbolic tangent and their variants and combinations).

The control device 24 controls the semi-active damper 22, that is to say it transmits control signals to the semi-active damper 22 in order to modify the behavior of the latter as a function of the conditions Operating. The control signals are, for example, control currents applied to the semiactive damper 22, the intensity of the current varying from one control current to another to modify the behavior of the semiactive active damper 22.

As illustrated in FIG. 3, the control device 24 comprises an accelerometer 26, a control unit 28, a control unit 30, a displacement detector 32 and a modeling unit 34. As illustrated in FIG. 4, according to a advantageous embodiment, the control device 24 also comprises a bandpass filter 36, a first lowpass filter 38 and a second lowpass filter 40.

The accelerometer 26 measures the transverse acceleration of the body 12, the transverse acceleration being the acceleration in the direction perpendicular to the direction of movement of the rail vehicle 10. The accelerometer 26 transmits an acceleration signal S1 comprising the measurement transverse acceleration.

The control unit 28 receives the acceleration signal S1 transmitted by the accelerometer 26.

The control unit 28 determines a setpoint effort to be made by the semi-active damper 22 in order to minimize the transverse oscillations of the body 12 from the acceleration signal S1.

Advantageously, the control unit 28 determines the setpoint effort by means of a hybrid control algorithm. The hybrid control algorithm is a combination of an algorithm of the "Acceleration Driven Damping Control" type (and "Controlling Damping Driven by Acceleration" in French) and an algorithm of the "Skyhook" type (or "Imaginary damper" in French).

The algorithms of the “Acceleration Driven Damping Control” and “Skyhook” type are well known to those skilled in the art and are for example described in “Semi-Active Control Strategies for High-performance Motorcycle”, or “Semi-Active Control Strategies pour Deux-Roues Motorisé Haute Performance ”in French, Savaresi & al and in“ A New Type of Hybrid Semi-Active Control Strategy in the Application of High-Speed Railway Vehicle Vibration Control ”,“ A New Type of Semi-Active Control Strategy Active Hybrid Applied to Vibration Control of High-Speed Rail Vehicle ”in French, Yingying & al.

The "Acceleration Driven Damping Control" type algorithm uses the transverse acceleration of the body 12 measured by the accelerometer 26 as input.

The “Skyhook” algorithm uses as input the transverse speed of the body 12 determined from the accelerometer 26 via an integrator module, not shown in the figures, determining the transverse speed of the body 12 from the acceleration signal S1.

Hybridization between the two algorithms is carried out by means of the passband filter 36 producing a progressive phase shift for increasing frequencies. This bandpass filter results in a phase signal close to 0 compared to the input signal for low frequencies, in particular for frequencies below 0.6 Hz, thus producing a signal similar in nature to that of l acceleration measured by the accelerometer 26. At higher frequencies, in particular for frequencies above 5 Hz, the phase shift is gradually increased until a phase delay close to 90 ° is obtained, producing a signal similar to that resulting from '' integration, down to the amplitude level. In the low frequency range for which the semi-active damper is very reactive, the accelerations applied in the body are directly compensated by the effort produced. At high frequencies a "Skyhook" control strategy is applied and in the intermediate frequency range we have a hybridization of the two control strategies. For frequencies strongly above 5 Hz, in particular for frequencies above 15 Hz, a field in which the reactivity of the semi-active damper tends to deteriorate, the transfer function of the bandpass filter offers a low bandwidth so as not to introduce inappropriate forces into this frequency range. From the point of view of the "Skyhook" control strategy, the use of the bandpass filter 36 also makes it possible to offer a phase advance for the frequencies around 1.5 Hz and beyond, thus making it possible to compensate the reaction time of the shock absorber approximately by anticipating the control signal by a fraction of a period.

The control unit 28 transmits an effort signal S2 including the setpoint effort.

The control unit 30 receives the effort signal S2 transmitted by the control unit 28.

The control unit 30 determines a control current Ic from the force signal S2 to be applied to the semi-active damper 22 so that the semi-active damper 22 exerts a force as close as possible to the force setpoint determined by the control unit 28.

The control unit 30 transmits a control signal S3 corresponding to the control current le to the modeling unit 34 and to the semi-active damper 22.

The detector 32 measures the displacement of the semi-active damper 22. By displacement measurement is meant the measurement of the distance separating the two ends 41 and 42 along the line of action of the semi-active damper 22.

The detector 32 transmits a displacement signal S4 comprising the measurement of the displacement.

The modeling unit 34 receives the control signal S3 transmitted by the control unit 30 and the displacement signal S4 transmitted by the detector 32.

The modeling unit 34 determines a state variable characteristic of the displacement of the semi-active damper 22 and advantageously of the orientation and the level of force of the semi-active damper 22, by means of a model. theoretical of the semi-active shock absorber 22.

A good compromise for a real-time application between the representative character and the computation time is represented by the Maxwell model which is illustrated in Figure 2. The theoretical Maxwell model includes an ideal damper 43 in series with an ideal spring 44 The ideal damper 43 is linked to the bogie 16 assumed to be fixed in the Maxwell model. The ideal damper 43 is characterized by a non-linear damping coefficient c in speed. The ideal spring 44 is characterized by a stiffness constant k.

In Figure 2, the distance between the ends of the semi-active damper 22 is noted x. The distance between the ends of the ideal damper 43 is noted y.

The characteristic state variable is advantageously the relative speed of movement of the ends of the ideal damper 43 denoted ÿ.

Maxwell's model gives the following equations:

dt x (y (t) - x (t)) c (t)

F (t) = -k * y (t) + k * x (t) + F _offset k

c {t)

F = dc (t) where F _offset is a unidirectional offset force which can be approximated by a constant force applied between the two ends of the damper at any time. This effort is conventional for any single-rod damper for which the fluid is kept under pressure by a compensation device making it possible to avoid the phenomenon of cavitation.

The theoretical model makes it possible to represent the semi-active damper 22 and to characterize its state by taking account of the stiffnesses which cause the hysteresis behavior by storing and restoring cyclically deformation energy. Hysteresis is called the property of a system whose state depends on the history of the stresses to which it has been subjected. Here, due to the internal stiffnesses of the semi-active damper 22, the state of the semi-active damper 22 is therefore not solely related to the applied control current. Failure to take into account this hysteretic behavior leads to significantly degrading the potential of the damping device 20.

As illustrated in FIG. 4, the modeling unit 34 advantageously comprises a derivative module 46, a configuration module 48 and a calculation module 50.

The derivative module 46 receives the displacement signal S4 transmitted by the detector 32 via the low-pass filter 38 making it possible to limit the frequency range of the displacement signal to the useful part in order to obtain an exploitable speed signal S6.

The derivative module 46 determines the speed of movement of the semi-active damper 22 relative to the bogie 16 from the displacement signal S4.

The derivative module 46 transmits the speed signal S6 comprising the speed of movement of the semi-active damper 22 between its two moving parts, for example to the calculation module 50. The quantity transmitted to the calculation module 50 depends on the physical positioning of the sensor corresponding within the shock absorber.

The configuration module 48 receives the control signal S3 transmitted by the control module 30 corresponding to the control current to be applied to the semi-active damper 22.

The configuration module 48 determines the value of the damping coefficient c of the ideal damper 43 and the value of the derivative of the damping coefficient c with respect to the speed of movement ÿ. The speed of movement is determined by the calculation module 50. The value of the speed of movement of the damping element 43 is zero during the first calculation carried out by the configuration module, the vehicle being stationary.

The parameterization module 48 transmits a parameterization signal S7 comprising the value of the damping coefficient c of the ideal damper 43 and the value of the derivative of the damping coefficient c with respect to the speed of movement ÿ, the signal of S7 parameterization being transmitted to the calculation module 50.

The calculation module 50 receives the movement signal S4, the speed signal S6 and the parameterization signal S7.

The calculation module 50 determines the state variable characteristic of the displacement of the semi-active damper 22 by means of the theoretical model.

The calculation module 50 transmits the state signal S5 comprising the state variable to the control unit 30 and to the parameterization module 48.

The parameterization module 48 receives the status signal S5, the determination of the value of the damping coefficient c of the ideal damper 43 and of the value of the derivative of the damping coefficient c with respect to the speed of movement ÿ being carried out on the basis of this status signal S5, which preferably corresponds to the speed of movement of the ideal damper 43.

Advantageously, the configuration module 48 uses a non-linear curve as a function of the speed ÿ for the damping coefficient c of the ideal damper 43 determined a priori from experimental measurements of the force produced by an experimental damper, analogous to the semi-active damper 22. This curve can be the result of a readjustment of the Maxwell model and of the parameterization module 48 at different working speeds of the ends of the experimental damper and different intensities of the control current. This recalibration can be done on the basis of a sinusoidal excitation at different working speeds and different control currents by measuring the resulting force exerted by the experimental damper and the comparison with the numerical model then the registration of the curve no -linear characteristic of the ideal shock absorber 43 and of the stiffness k. The characteristic of the non-linear damper can be represented in the form of a damping force curve as a function of a working speed ÿ.

The calculation module 50 and the parameterization module 48 thus readjusted make it possible to provide in real time respectively a value of the state variable ÿ and a value of the instantaneous damping coefficient c and its derivative. The last two elements are determined from the non-linear curve F (ÿ) giving the characteristic of the ideal damper 43 using the following equations:

of F (| ÿ |) X y - sign (y) XF (| y |) dÿ ÿ ²

The control unit 30 receives the state signal S5.

The control unit 30 determines the control current le. The control current corresponds to the control current optimized thanks to the theoretical model of the modeling unit 34. The control current thus allows it to avoid the problems due to the hysteresis behavior of the semi-active damper 22 and to obtain an optimal damping of the transverse oscillations of the body 12.

The control unit 30 transmits the control current Ie to the semi-active damper 22.

The semi-active damper 22 receives the control current le and applies the damping force associated with the control current le to the body 12 in order to compensate for the transverse oscillations of the body 12.

The bandpass filter 36 variably filters the different frequency ranges of the acceleration signal S1 at the output of the accelerometer 26 and induces a variable phase shift as a function of the frequency. It is the element allowing the hybridization between the "Acceleration Driven Damping Control" algorithm and the "Skyhook" algorithm.

The bandpass filter 36 transmits the filtered acceleration signal S1 to the control unit 28.

Advantageously, the bandpass filter 36, the Bode diagram of which is illustrated in FIG. 5, is a second order infinite impulse response filter which lets the frequencies pass substantially between 0.25 Hz and 1.5 Hz and attenuates the rest. frequencies. The characteristic of such a filter is suitable for a wide range of railway equipment for main line application.

Advantageously, the hybrid control algorithm uses the algorithm of the “Acceleration Driven Damping Control” type for the signals having a frequency lower than 0.6 Hz and uses the algorithm of the “Skyhook” type for the signals having a frequency greater than 5 Hz.

Between the two frequency ranges, the two control laws are hybridized by the bandpass filter 36 with a gradual increase in the "Skyhook" algorithm for increasing frequencies. The hybrid control algorithm thus uses each algorithm in the frequency range where the response time of the damper is adapted. In the range of very low frequencies, the shock absorber is able to compensate with a negligible reaction time the accelerations applied to the body 12. This is no longer the case at higher frequencies for which a "Skyhook" strategy is more suitable.

The first low-pass filter 38 receives the displacement signal S4 transmitted by the detector 32.

The first low-pass filter 38 attenuates the high frequencies, advantageously above 100 Hz.

The first low-pass filter 38 facilitates processing and in particular bypass operations.

The first low-pass filter 38 transmits the filtered displacement signal S4 to the derivative module 46 and to the calculation module 50.

The second low-pass filter 40 receives the control signal S3 transmitted by the control unit 30.

The second low-pass filter 40 attenuates the high frequencies, advantageously above 100 Hz.

The second low-pass filter 40 avoids entering high frequencies into the digital model and makes it possible to avoid the generation of significant forces in a frequency range for which the Maxwell model or any other rheological model are no longer representative.

The second low-pass filter 40 transmits the filtered control signal S3 to the configuration module 48.

A method of controlling the semi-active damper 22, using the advantageous variant of the semi-active damper 22 shown in Figure 4, will now be described.

Initially the vehicle is stationary and the transmitted values of displacement, acceleration, damping coefficient and its derivative with respect to speed are generally zero.

The accelerometer 26 measures the transverse acceleration of the body 12 and transmits the acceleration signal S1 to the bandpass filter 36.

The bandpass filter 36 receives the acceleration signal S1 and lets the frequencies pass substantially between 0.25 Hz and 1.5 Hz while attenuating the rest of the frequencies.

Advantageously, the bandpass filter 36 processes the acceleration signal S1 and achieves a progressive phase shift for increasing frequencies.

The bandpass filter 36 then transmits the acceleration signal S1 to the control unit 28.

The control unit 28 receives the filtered acceleration signal S1 and determines the target force from the filtered acceleration signal S1 by means of the hybrid control algorithm.

The hybrid control algorithm uses the "Acceleration Driven Damping Control" type algorithm for signals with a frequency less than 0.6 Hz and uses the "Skyhook" type algorithm for signals with a frequency greater than 5 Hz.

Between the two frequency ranges, the two control laws are hybridized by the bandpass filter 36 with a gradual increase in the "Skyhook" algorithm for increasing frequencies.

The control unit 28 then transmits the control signal S2 to the control unit 30.

The control unit 30 receives the control signal S2. The control unit 30 transmits the control signal S3 to the second low-pass filter 40 and to the semi-active damper 22 which applies the damping force associated with the control signal S3 to the body 12.

The second low-pass filter 40 receives the control signal S3 and attenuates the high frequencies of the control signal S3.

The second low-pass filter 40 then transmits the filtered control signal S3 to the configuration module 48.

The parameterization module 48 receives the filtered control signal S3 and determines the value of the damping coefficient c of the ideal damper 43 and the value of the derivative of the damping coefficient c with respect to the speed of movement ÿ. At the first iteration, with the vehicle stationary, the value of the damping coefficient c of the ideal damper 43 and the value of the derivative of the damping coefficient c relative to the speed of movement are zero.

The parameterization module 48 transmits the parameterization signal S7 to the calculation module 50.

The detector 32 measures the displacement of the semi-active damper 22 and transmits the displacement signal S4 to the first low-pass filter 38.

The first low-pass filter 38 receives the displacement signal S4 and attenuates the high frequencies of the displacement signal S4.

The first low-pass filter 38 then transmits the filtered displacement signal S4 to the derivative module 46 and to the calculation module 50.

The derivative module 46 receives the filtered displacement signal S4 and determines the displacement speed of the semi-active damper 22 relative to the bogie 16 from the displacement signal S4.

The derivative module then transmits the speed signal S6 to the calculation module 50.

The calculation module 50 receives the filtered movement signal S4, the speed signal S6 and the parameterization signal S7. The values transmitted via the S7 parameterization signal are initially zero.

The calculation module 50 determines the speed relatif of relative displacement of the ends of the ideal damper 43 using the Maxwell model.

The calculation module 50 transmits the state signal S5 to the configuration module 48 and to the control unit 30.

The parameterization module 48 receives the status signal S5, the determination of the value of the damping coefficient c of the ideal damper 43 and of the value of the derivative of the damping coefficient c with respect to the speed of movement v being carried out from the state signal S5 and the characteristic curve F (ÿ) determined from the experimental measurements on the experimental damper.

The control unit 30 receives the state signal S5.

The control unit 30 determines / modifies the control current Ie from the state signal S5. At the first iteration, the vehicle being stopped, the state signal S5 is zero.

The control unit 30 transmits the control current Ie to the semi-active damper 22 and to the low-pass filter 40.

The semi-active damper 22 receives the control current le and applies the damping force associated with the control current le to the body 12.

The process described above is repeated periodically in order to modify in real time the behavior of the semi-active damper 22 as a function of the operating conditions.

More generally, in the embodiment of FIG. 4, during a given iteration of the process, the parameterization module determines, for example, the signal S7 from the value of the status signal S5 and the value of the signal of command S3 in the previous iteration.

More generally in the embodiments of FIGS. 3 and 4, during a given iteration of the method of controlling the damper 22, the modeling unit 34 determines, for example, the status signal S5 from the value of the control signal S3 on the previous iteration.

Thanks to the characteristics described above, the control of the control device 24 of the semi-active damper 22 is improved significantly. Indeed, the use of the theoretical model makes it possible to determine a state variable characteristic of the semi-active damper 22 making it possible to take into account the hysteretic behavior due to the rigidities of the semi-active damper 22 by a precise knowledge of the meaning and the level of force actually applied by the shock absorber at all times. This is not the case with conventional strategies, which are simply based on the speed measured at the terminals of the shock absorber. In addition, the use of a bandpass filter 36 at the input of the control unit 28 allows an advantageous combination of the control laws "Acceleration Driven Damping" and "Skyhook". The damping device 20 allows optimal damping of the body 12 by limiting the phase difference between the force actually applied by the semi-active damper 22 and the theoretical control force. The transverse oscillations of the body 12 are therefore significantly reduced and thus the comfort of travelers in the rail vehicle 10 is improved.

Claims (10)

1Damping device (20) of a vehicle (10), in particular rail, comprising: - a semi-active damper (22); and - a control device (24) configured to control the semiactive damper (22), the control device (24) comprising: - an accelerometer (26) capable of measuring the transverse acceleration of the vehicle (10) and transmitting an acceleration signal (S1) comprising the measurement of the transverse acceleration; - a control unit (28) configured to receive the acceleration signal (S1), determining a setpoint effort to be made by the semi-active damper (22) from the acceleration signal (S1) in order to minimize the transverse oscillations of the vehicle (10) and transmit a force signal (S2) comprising the target force; - a control unit (30) configured to receive the force signal (S2), and transmit a control signal (S3), a function of the force signal (S2), to the semi-active damper (22) ; characterized in that the control device (24) also comprises: - a displacement detector (32) capable of measuring the displacement of the semi-active damper (22) and transmitting a displacement signal (S4) comprising the measurement of the displacement; and - a modeling unit (34) configured to receive the control signal (S3) and the displacement signal (S4), determining a state variable characteristic of the displacement of the semi-active damper (22) by means of a theoretical model of the semi-active damper (22) and of the control (S3) and displacement (S4) signals and transmitting a status signal (S5) comprising the characteristic state variable to the control unit (30), the control unit (30) being able to determine the control signal (S3) also from the status signal (S5). 2, - Damping device (20) according to claim 1, wherein the theoretical model is a Maxwell model comprising an ideal damper (43) in series with an ideal spring (44). 3. - Damping device (20) according to claim 2, in which the modeling unit (34) is capable of determining the damping coefficient (c) of 15 the ideal shock absorber (43) from experimental measurements of the force produced by an experimental shock absorber (43), analogous to the semi-active shock absorber (22). 4. - Damping device (20) according to claim 2 or 3, wherein the characteristic state variable is the relative speed of movement of the ends of the ideal damper (43). 5. - Damping device (20) according to any one of the preceding claims, comprising a bandpass filter (36) configured to filter the acceleration signal (S1) at the output of the accelerometer (26). 6. - Damping device (20) according to claim 5, in which the bandpass filter (36) is configured to let the frequencies pass substantially between 0.25 Hz and 1.5 Hz and attenuate the rest of the frequencies. . 7. - damping device (20) according to any one of the preceding claims, in which the control unit (28) is configured to use a hybrid control algorithm, the hybrid control algorithm being composed of a “Acceleration Driven Damping Control” type algorithm combined with a “Skyhook” type algorithm. 8. - Damping device (20) according to claim 5 or 6 and claim 7 in which the bandpass filter (36) is a second order filter with infinite impulse response and in which the control unit (28 ) is configured for: - apply the "Acceleration Driven Damping Control" type algorithm to signals with a frequency below 0.6 Hz, - apply the "Skyhook" type algorithm to signals with a frequency higher than 5 Hz, - apply the "Acceleration Driven Damping Control" type algorithm with the "Skyhook" type algorithm to signals having a frequency between 0.5 Hz and 5 Hz, with a gradual increase in the weight of the algorithm. "Skyhook" type with frequency. 9. - Method for controlling a semi-active damper (22) according to any one of claims 1 to 8 comprising the following steps: - measurement of the transverse acceleration of the vehicle (10) and transmission of the acceleration signal (S1) by the accelerometer (26); - reception of the acceleration signal (S1), determination of the setpoint effort and transmission of the effort signal (S2) by the control unit (28); 5 - reception of the force signal (S2) and transmission of the control signal (S3) to the semi-active damper (22) by the control unit (30); - measurement of the displacement of the semi-active damper (22) and transmission of the displacement signal (S4) by the detector (32); - reception of the displacement signal (S4), determination of the state variable 10 characteristic and transmission of the state signal (S5) by the modeling unit (34); and - reception of the status signal (S5), determination of the control signal also from the status signal (S5) and transmission of the control signal (S3) to the semi-active damper (22) by the unit control (30).