GB2267259A

GB2267259A - Generating signals for controlling or regulating a chassis

Info

Publication number: GB2267259A
Application number: GB9310457A
Authority: GB
Inventors: Rainer Kallenbach; Andreas Klug; Peter Meissner; Stefan Otterbein
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1992-05-26
Filing date: 1993-05-20
Publication date: 1993-12-01
Anticipated expiration: 2013-05-20
Also published as: JPH06278443A; DE4217325A1; GB9310457D0; GB2267259B; FR2691676A1

Abstract

A method and a device for generating signals for controlling or regulating a chassis, of controllable or regulatable movement cycles, of a passenger car and/or commercial motor vehicle are presented. Starting from the compression movements between the vehicle body and the wheels and from the longitudinal and/or transverse movements of the vehicle, according to the invention the suspension systems between the body and wheels are activated in such a way as to exert forces which are proportional to the modal speeds of the body. A separate adjustable damping of the forms of natural oscillation of the body is thereby possible. That is to say, the damping proportional to modal speed is based on the skyhook regulation notion in as much as forces are exerted by activations of the suspension systems such that the individual forms of natural oscillation of the body can be "skyhook-damped" separately from one another. <IMAGE>

Description

1- 2267259 Method and device for generating signals for controlling or

regulating a controllable or regulatable chassis State of the art

The invention proceeds f rom a method and a device according to the precharacterising clause of Claim 1 and of Claim 9 respectively.

To improve the motoring comfort of passenger cars and/or commercial motor vehicles, the design of the chassis is of essential importance. Efficient springing and/or damping systems as integral parts of a chassis are necessary for this purpose.

In the passive chassis still used predominantly hitherto, the springing and/or damping systems, when installed, are designed either to tend to be hard ("sporting") or to tend to be soft ("comfortable"), depending on the projected use of the vehicle. With these systems, it is not possible to influence the chassis characteristic during motoring.

In contrast, where active chassis are concerned, the characteristic of the springing and/or damping systems can be influenced during motoring by the effect of a control or regulation, depending on the driving state.

To control or regulate such an active chassis, the vehicle-occupant/loadvehicle-road system must be considered first. The vertical movements of the vehicle body are felt by the vehicle occupants or by a load susceptible to shocks to be detrimental to motoring, comfort. The causes of these movements of the body are essentially incitements caused by unevenness of the road, on the one hand, and variations in the driving state, such as steering, braking and acceleration, on the other hand.

The aim is, therefore, to achieve a high motoring comfort by minimising the body movements of the vehicle. In order to counteract the body movements with reducing effect by means of an active springing andlor damping system, two strategies can be adopted.

On the one hand, the causes of the body movements can be detected. That is to say, the road unevenness is recognised before the vehicle reaches this. This is described, for example, in German Patent Specification 1, 158,385. Furthermore, variations in the driving state, such as steering, braking and acceleration, can be recognised as further causes, virtually before their effect on the vehicle body, by observing the corresponding actuators. For example, the steering angles and/or variations in the throttle-f lap position can be detected, in order to recognise steering and/or accelerating manouevres. In this case, therefore, an effective minimising of the body movements can be activated as it were at the same time as they occur.

On the other hand, the body movements can be determined and these be counteracted by means of an active chassis. The determination can take place directly by measurement. for example by the use of acceleration sensors, or indirectly by "reconstruction", for example by measuring the compression movement and by the use of reconstruction methods.

The implementation of the first strategy has disadvantages in respect of the sensing of the road unevenness, since sensors, for example ultrasonic sensors or optical sensors, which are constructed at a high outlay, are required for this.

A chassis regulation which works according to the second strategy is described, for example,' in German Offenlegungsschrift 3,738,284. Here, the body.movements c 3 R. 25249 are measured as body accelerations. A disadvantage of such systems is that acceleration sensors which involve a relatively high outlay and which are expensive are necessary.

European Preliminary Publication 0,321,078 describes a chas s is regulating system, in which local accelerations of the vehicle body are determined without acceleration sensors. The springing and/or damping systems are mounted between the respective wheel units and the body. In particular, the local body speeds at the points of engagement of the springing and/or damping systems on the body are reconstructed from the signals of the relative movements between the body and the wheel units, with the damping force being ignored. These local body movements are then used to control and/or regulate the respective local springing and/or damping system with the effect of minimising this local body speed.

The system described in European Preliminary Publication 0,321,378 has essentially three disadvantages.

1. The determination of the local body speeds and the local minimising of these has the result that collective body movements, such as pitching, swaying and lifting movements, remain largely unaccounted for. A deliberate influencing of these collective body movements with the effect of reducing them is therefore impossible.

2. The method for reconstructing the body movement from the compression movement provides useful results only during travel in a straight line at a constant driving speed (incitement by ground unevenness); there is therefore no guarantee that the body movement will be minimised during steering, braking and/or accelerating manoeuvres.

3. In particular, ignoring the damping force has not proved the best possible course in the reconstruction of the local body speed, since, ' in general, the 4 R. 25249 damping force, when compared with the spring force, cannot be ignored.

German Offenlegungsschrift 3,408,292 describes a fully active springing system, in which, starting from the distances between the vehicle body and the wheels (compression travels), an averaged height position, an averaged pitching angle and an averaged swaying angle of the vehicle body relative to the ground are calculated. Actuating forces are thereupon determined, and on the basis of these the supporting units arranged between the wheels and the vehicle body are activated, in order to adapt the previously calculated average height position or the calculated pitching and swaying angles to desired values in a predeterminable way. The influences of nonstationary driving states (steering, braking, acceleration) are not taken into account in this. Because the averaged body movements are determined and because the influences of non- stationary driving states are ignored, a deliberate influencing of the body movements actually ocurring instantaneously cannot be achieved in this system.

Furthermore, the body movement in the form of lifting, swaying and pitching movements is described in German Offenlegungsschrift 3,408,292, and it is these (movement) components too which are influenced independently of one another by means of the regulation. However, the choice of these components is not the only possible one: thus, the body movement can also be described, for example, in terms of:

- the swaying movement and the vertical movement of two points in the front and the rear body region - the vertical movement of three points of the body (which do not lie on a straight line) - the three so-called modal movement components (this expression is explained further below), R. 25249 and it is also possible, by means of an active chassis, to influence one of these sets of movement components, specifically each component independently of the other.

In German Patent Application P 4039629.0-21, the body movements occurring instantaneously in the form of lifting, pitching and swaying movements are reconstructed by means of a dynamic filtering of the measured compression movements, and taking into account the longitudinal and/or transverse movements of the vehicle. Proceeding from this, by special weighting, so-called weighted body speeds are determined at the points of engagement of the suspension systems on the vehicle body and are counteracted in a known way by activations of the suspension systems. The weighting in this case is carried out by evaluating the modal movement components of the body to a differing degree.

In German Patent Application P 4117897.1, proceeding from measured signals which represent the local body movements of the vehicle at selected locations on the body, conclusions are drawn as to the body movements occurring instantaneously in the form of lifting, swaying and pitching movements. Proceeding from this, the instantaneous modal movement components of the body are determined and are weighted to a differing degree in dependence on driving manoeuvres. Forces which are linear in the modal speeds of the body are exerted by activations of the suspension systems.

The object of the present invention is to develop a simple and inexpensive system for chassis regulation, by means of which a deliberate and separate damping of the body movements actually occurring instantaneously is possible.

Claims

This object is achieved by means of the features characterised in Claims 1 and 9. Advantages of the invention Proceeding from a simple sensor arrangement for acquiring the compression movements between the vehicle body and the wheels and for acquiring the longitudinal and/or transverse movements of the vehicle, the present invention has the advantage that. as a result of the activations according to the invention of the suspension systems between the body and the wheels, forces are exerted in such a way that the forms of natural oscillation of the vehicle body can be damped separately from one another. That is to say, forces which are proportional to the modal speeds of the body are exerted by means of the suspension systems. For this purpose, the currently occurring modal speeds of the vehicle body are determined from signals which represent the compression movements and from signals which represent the longitudinal andlor transverse movements of the vehicle, with characteristic quantities of the springing and/or damping elements of the suspension systems being taken into account. Forces which are linear in the modal speeds of the body are then exerted by activations of the suspension systems. A separate adjustable damping of the body speeds occurring instantaneously is hereby possible. In other words, the damping proportional to modal speed is based on the skyhook regulation notion, in as much as, by activations of the suspension systems, forces such that the individual forms of natural oscillations of the body can be "skyhook-damped" separately from one another are exerted. In an advantageous embodiment of the invention, the modal speeds are influenced additively and/or multiplicatively in dependence on quantities representing and/or influencing the driving state. Advantageous, furthermore, is the acquisition of the transverse movements of the vehicle by steering-angle sensors and/or by a corresponding evaluation of the 7 R. 25249 signals from wheel-speed sensors. The signals from wheelspeed sensors are, in turn, suitable for acquiring the longitudinal movements of the vehicle. Moreover, appropriately positioned acceleration sensors can also be used for acquiring the transverse and longitudinal movements of the vehicle. It is advantageous to use the invention particularly in the activation of semi-active continuously adjustable suspension systems. Such semi-active continuously adjustable suspension systems are conventionally designed as springing and/or damping elements, the springing and/or damping properties of which are continuously adjustable. Whereas forces can be exerted independently of the compression movements by means of fully active suspension systems, it is advantageous, when semi-active continuously adjustable chas s is -regulating systems are used, to select a maximum hard or soft setting as a substitute for a desired force which cannot be put into practice. This is described, for example, in German Offenlegungsschrift 3,524,862. An especially advantageous embodiment of the invention involves the selectable distribution of the rolling or swaying moment of the vehicle. It is hereby possible, for example, to influence the steering behaviour of the vehicle, such as understeering, oversteering or neutral steering behaviour. In addition to the method according to the invention, the invention also relates to a device for carrying out the method according to the invention. Advantageous embodiments of the invention are characterised in the subclaims. Drawings An exemplary embodiment of the invention is illustrated in the drawings and is explained in more detail in the R. 25249 following description. Figure 1 shows a three-dimensional vehicle model, whilst Figure 2 illustrates the essential elements of the invention. Description of the exemplary embodiment To explain the expressions "form of natural oscillation", "modal co- ordinate,, and "principle oscillation", the following should first be noted: Like any oscillatory system, a vehicle (or its vertical movement) also has a specific number of forms of natural oscillation ("modes") with associated modal or principle co-ordinates (,,modal co-ordinates"). Each (vertical) movement of the vehicle can be thought of as being composed at any moment of the forms of natural oscillation, but the fraction by which each individual form of natural oscillation is involved in the movement varies in the course of time. The significance of the modal co-ordinates is that they described quantitatively the distribution of the fractions or of the components: at any moment of the movement, the value of each modal co-ordinate is identical to the fraction by which the associated form of natural oscillation contributes to the movement. Special (vertical) movements of the vehicle are its principle oscillations ("modal motions"): these are characterised in that only a single form of natural oscillation is represented during the entire movement; consequently, all the modal co-ordinates, with only one exception, always have the value zero. To describe the (vertical) movement of the body, the co-ordinates,lift" (vertical displacement of its centre of gravity), swaying angle (rotation about its longitudinal axis) and pitching angle (rotation about its transverse axis) are often used in vehicle engineering. If these coordinates are also modal co-ordinates, there exists, for example, a "principle pitch oscillation", in 9 R. 25249 which a pure pitching movement occurs in the sense that the centre of gravity is at rest and also no swaying movement takes place (the lift and sway components are not represented). In contrast, if only the swaying angle is a modal co-ordinate, then two of the principle oscillations are coupled lifting and pitching movements: the vertical movement of the centre of gravity is linked to a pitching movement, and vice versa; in one of these principle oscillations, the lift component is dominant ("much" lift and "little" pitching), whilst the pitch component predominates in the other. Whether the lift, the swaying angle and the pitching angle of the vehicle body are actually modal coordinates depends essentially on two factors. On the one hand on the vehicle itself, and on the other hand on the manner in which the chassis regulating system is designed (fully active or semi active). It can be said, in general, that the swaying is a modal co-ordinate when the chassis is arranged longitudinally symmetrically on the body, and when the principle axes of inertia of the vehicle body coincide with its longitudinal, transverse and vertical axis. This vehicle property certainly applies to many of the present-day vehicles; it is valid regardless of the particular chassis-regulating systems used. In vehicles with a semi-active chas s is -regulating system which is obtained, for example, by a chassis having conventional springs and regulatable shock absorbers, the lifting and the pitching angle are not always also modal co-ordinates. In particular, this is the case only when there is a specific relation between the spring rigidities c,, c. of the supporting springs on the front and rear axles and the axle distances a and c relative to the centre of gravity of the body (ac, = cc,). Thus, when the ratio ac,/cc, is approximately equal to one, a practically effective, (almost ideally) uncoupled influencing of lifting, swaying and pitching movements can be achieved. Important f or practical purposes is a second case, in which there is a special relation between the mass moment of inertia IN of the body relative to its transverse axis, its mass mk and the axle distances a and c (I. = mkac); this relation applies, at least approximately, to many of the present-day vehicle types. In this case, the modal co-ordinates, in addition to the swaying angle, are given by the vertical displacements (z, and z.) of the body at the "front" and "rear". It is therefore possible and even expedient here to influence the movement of the body at the "front" and "rear" and the swaying movement independently of one another by means of the regulation. In the exemplary embodiment to be described below, the following steps are carried out: 1. Proceeding from the compression-movement signals. instantaneously occurring fractions of the body movement are first determined by means of dynamic filters. These fractions reproduce the body movement actually occurring instantaneously only in the case in which the vehicle is travelling unaccelerated (longitudinal acceleration equal to zero) in a straight line (transverse acceleration equal to zero). (The body movements are incited by ground unevenness.) 2. Furthermore, corrections of the body-movement fractions determined under 1. are then carried out by appropriately taking into account the longitudinal and/or transverse movements of the vehicle. Only by thus taking into account the longitudinal andlor transverse movements, which may differ from zero, can the body movements actually occurring be determined completely during all driving manoeuvres. The description of the body movement can be carried out in different sets of co-ordinates (three in each case), for example in - lift, swaying angle and pitching angle, - li - R. 25249 - swaying angle and vertical displacements of the body at two points, f or example in the f ront and the rear body region, - modal co-ordinates. 3. Subsequently, the description of the body movement in modal components (transformation of the instantaneous values of the selected co-ordinates to those of the modal co-ordinates) takes place. These are dependent on the mass distribution and on the suspension system and therefore have to be previously determined for each vehicle separately. It is especially expedient if the body movement determined in point 1 and completed in point 2 is given immediately in modal co-ordinates; for there is then no need for point 3. 4. The modal movement components are now weighted independently of one another. This corresponds to a weighting of the forms of natural oscillation, since the instantaneous values of the modal co-ordinates of course reproduce the instantaneous fractions by which the associated forms of natural oscillation are represented in the movement. Thus, the swaying movement of the body during cornerings (acquisition by transverse acceleration) is weighted to a greater degree. During braking and/or accelerating manoeuvres (acquisition by longitudinal acceleration), the lifting and pitching movements or depending on the forms of natural oscillation, the vertical body movements at the front and rear are appropriately weighted to a greater degree. 5. The weighted instantaneous values of the modal movement components are now converted into weighted lifting, swaying and pitching movements (inverse transformation of the weighted modal co-ordinates to weighted lift, sway and pitch co-ordinates). Activation signals of the suspension systems, which represent desired forces, are subsequently obtained by R. 25249 means of the "force-distribution matrix". The choice of the elements of the force-distribution matrix also additionally affords the possibility of choosing a selectable rolling-moment or swaying-moment distribution of the vehicle. In the exemplary embodiment, the system according to the invention for controlling or regulating a chassis will be demonstrated by means of a block diagram. In this exemplary embodiment, the vehicle possesses four wheel units and two axles. Furthermore, in this exemplary embodiment, it will be assumed in the first place that the lifting, pitching and swaying movements are the modal movement components of the vehicle body. Figure 1 shows a simple, three-dimensional model of a longitudinally symmetrical four-wheel and two-axle vehicle. The associated axle is designated below by the index i, that is to say the properties belonging to the rear axle are described by the index i=h and the properties belonging to the front axle are described by the index i=v. Entry 30 represents springing and damping systems which each consist of a spring having the spring constant Ci and of a shock absorber arranged in parallel and having the damping constant di. The wheels are designated by entry 31 and, in model terms, are each described by the bodies arranged in succession and having the masses Mri and the spring representing the wheel rigidity and having the spring constant Cri. The road is marked by entry 33 and the body having the mass Mk is marked by entry 32. The centre of gravity S of the vehicle body is located at the distance a from the front axle and at the distance c from the rear axle. b denotes half the wheel gauge. Figure 2 shows the essential elements of the system in the exemplary embodiment. The entries lvl, lvr, lhl and 1hr denote sensors and the entry 2 designates by a border represented by broken lines a first filter combination of filter units 11, 12 and 13. Entry 3 denotes by a border represented by broken lines units for additive and/or multiplicative influencing, entries 16 and 17 describing additive linkages and entries 18, 19 and 20 multiplicative linkages. The entries 14 and 15 represent filter units. Entry 4 shows by a border represented by broken lines a second filter combination of filter units 21, 22, 23 and 24 and entry 5 describes by a border represented by broken lines the suspension systems 25v1, 25vr, 25hl and 25hr to be activated. The entries 6 and 7 mark means for the acquisition of the transverse and longitudinal movement of the vehicle. The functioning of the system described in this exemplary embodiment, for generating signals for controlling or regulating an active chassis, is explained below by Figures 1 and 2. For each wheel unit or springing and/or damping system, a respective sensor lvl, lvr, lhl and 1hr detects the relative movements between the wheel and vehicle body, such as, for example, the relative compression travel and/or the compression speed and/or quantities associated with these, such as, for example, pressure differences in the damping systems. In this exemplary embodiment, the output signals are signals which represent the relative compression travels Zarij, the index i denoting the associated axle, that is to say the spring travels belonging to the rear axle are designated by the index i=h and the spring travels belonging to the front axle by the index i=v, and the index j denoting the vehicle side belonging to the signal, that is to say the right vehicle side is marked by j=r and the left side by j=l, the viewing direction being selected as being from the rear forwards. These signals can be obtained by direct measurements of the compression travel and/or by measuring the compressiontravel speed and/or quantities associated with these, such as, for example, pressure differences in the damping systems. In this exemplary embodiment, the signals Zarvl, Zarvr, Zarhl and Zarhr appear on the output side of the sensors Uj. These signals are fed to the 1st combination of filter units 2, where they are interlinked. This linkage takes place in the f ilter units 11, 12 and 13. These, like all the other filter units of the system, can be of the electronic digital type, f or example in computer units by the processing of a differential equation representing the transformation properties, or of the electronic analogue type, for example with electronic components by the simulation of a differential equation representing the transmission properties. The entire 1st filter combination 2 can be characterised by its transmission behaviour. The transmission behaviour can be represented as follows in matrix notation: (Sv Sv Sh Sh Sv/r -Sv/r Sh/r -Sh/r (1), -sv/p -sv/p Sh/q Sh/q in which Sv(s) = -(Cv+dvs)/(Mks) and Sh(s) = -(Ch+dhs)/(Mks) and 1/r = (bMk)/Iw and 1/p = (aMk)/In and l/q = (cMk)/In and s - the Laplace variable, a - the distance between the front axle and the centre of gravity of the body, c the distance between the rear axle and the centre of gravity of the body, b - half the wheel gauge, Mk - the mass of the body, Iw - the mass moment of inertia of the body in respect of its longitudinal axis, - is - R. 25249 In - the mass moment of inertia of the body in respect of its transverse axis, dv - the damping constant of the shock absorbers on the front axle, dh - the damping constant of the shock absorbers on the rear axle, Cv - the rigidity of the springs on the front axle, and Ch - the rigidity of the springs on the rear axle. The above-listed vehicle-specific parameters. such as the distances from the centre of gravity and the mass moments of inertia, must of course be known. There are many methods in the state of the art f or obtaining these data. Furthermore, these vehicle-specific parameters are dependent on the load state of the vehicle. Thus, particularly when it is loaded on one side, can changes in individual or several parameters occur. To overcome this problem, a plurality of courses can be adopted: - The system according to the invention is applied to the empty vehicle or to the vehicle with a typical load distribution. Deviations from the applied parameter set of the parameters actually occurring, can if the occasion arises, lead to slight variations in the effect of the system according to the invention, but without departing from the notions essential to the invention. - A choice of different parameter sets according to the load state is possible. Thus, the system according to the invention is always adapted to the particular prevailing conditions. In the lst filter combination 2, therefore, the signals of the compression travels are combined linearly, as described below. 16 - R. 25249 zb,' Sv Sv Sh Sh Zarv1 alphabl Sv/r -Sv/r Sh/r -Sh/r Zarvr betabl Sv/p -Sv/p Sh/q Sh/q Zarhl ) ( Zarhr) The interlinkages are obtained by formal mathematics by the matrix multiplication of the four-component vector (Zarvl, Zarvr, Zarhl, Zarhr) by the matrix (1) characterising the transmission behaviour. The individual filter units 11, 12 and 13 can be designed as addition units as follows, for example in accordance with the rules for vector matrix multiplication. Filter unit (FE) 11: ZarvlSv + Za=Sv + ZarhlSh + ZarhrSh Fe 12: ZarvIWr ZarvrSv/r + ZarhlSh/r ZarhrSh/r Fe 13: -ZarvlSv/p - ZarvrSv/p + ZarhlSh/q + ZarhrSh/q The linkage results emerging from this correspond to the lif ting, swaying and pitching speeds (zb 1, alphab 1 and betabl) of the vehicle body during unaccelerated travel in a straight line (incitement by ground unevenness). Here, the rotations of the vehicle body about its longitudinal and transverse axes are designated respectively by alphab and betab, and lift of the body is designated by zb. alphab', betabl and zbl are the respective first time derivations of the quantities alphab, betab and zb. It may be pointed out at this juncture, that the lst filter combination 2 comprises filters with dynamic transmission behaviour. Only by taking into account the dynamic behaviour of the wheel and the body is it possible to reconstruct the instantaneously occurring body movements from the compression movements. The linkage results (alphabl and betabl) at the output of the 1st filter combination 2 reproduce the instantaneously occurring swaying and pitching speeds (alpha, and beta,) only for the situation in which the vehicle is travelling unaccelerated in a straight line, whilst the lifting speed zbl is independent of the acceleration state of the vehicle, that is to say zb1=z'. Now if braking, accelerating and/or steering manoeuvres take place, the swaying and pitching speeds alphab, and betabl must be supplemented by the terms alphaqI = (Ew(s)aq)/(Iws) and betall = (En(s)al)/Ins) (2) by the additive linkages 16 and 17 in the units 3, in such a way that alph a, = alphabl+alphaq' and beta' = betabl+betal' and zbl = zI (3). In this, aq and al are the transverse and longitudinal accelerations of the vehicle which are acquired in the means 6 and 7. Ew and En are transmission functions, s representing the Laplace variable. The quantities Ew and En can be determined on the basis of tyre models. In a simple embodiment of the system according to the invention, the quantities Ew and En have the form Ew = hMk and En = -hMk (4), Mk representing the mass of the vehicle body and h the height of the centre of gravity of the vehicle. The lifting, pitching and swaying speeds (z', beta' and alpha,), which are supplemented in this way and which also reproduce the instantaneously occurring body movements in the case of steering, braking and accelerating manoeuvres, are weighted by the multiplicative linkages 18, 19 and 20. This is carried out by multiplications by the quantities gh, gw and gn and can be carried out separately from one another. - 18 R. 25249 It is advantageous to select the values gh, gw and gn as dependent on quantities which represent andlor influence the driving state, such that the driving speed, braking, steering and/or accelerating manoeuvres of the vehicle and/or the ambient temperature. The weighted lifting, pitching and swaying speeds (zg beta g r and alphag') thus appear on the output side of the 3rd filter units. Whilst the signals of the transverse and/or longitudinal acceleration aq and/or al appear at the inputs of the filter units 14 and 15, the signals alphaq, and betall appear on the output side of the filter units 14 and 15, the transmission behaviour of which can be described according to the equations (2) by Ew(s)/(Iws) for the filter unit 14 and En(s)/(Ins) for the filter unit 15. The signals which represent the transverse acceleration aq and the longitudinal acceleration al of the vehicle are acquired in the means 6 and 7. This can take place, for example, by means of suitable acceleration sensors. It is advantageous, however, to determine the signals of the transverse acceleration aq of the vehicle from the signals of a steering-angle sensor, especially when these signals are also used, for example, for controlling or regulating a power-assisted steering. It is advantageous, furthermore, to determine the signals of the longitudinal acceleration al of the vehicle from the signals of wheelspeed sensors which are also used, for example, in an anti-lock system. In conclusion, it must be said as regards the inf luencing in the units 3 that here, on the one hand, the actually occuring pitching and swaying speeds are reconstructed from the relative-travel signals between the body and the wheel units and from the signals representing the transverse acceleration aq and the longitudinal acceleration al of the vehicle and, on the other hand, a deliberate influencing of the body movements occurring instantaneously is possible, in order, for example, to emphasise or damp a specific movement particularly in the subsequent data evaluation and change-over of the damping characteristic. In the exemplary embodiment described hitherto, the vertical displacement of the centre of gravity of the body ("lift"), the rotation of the body about its longitudinal axis (swaying angle) and the rotation of the body about its transverse axis (pitching angle) were selected as co-ordinates for describing the body movements. Furthermore, the lifting, swaying and pitching movements also form those movement components which should be influenced independently of one another by means of the regulation. This is expedient, in particular, only when the lift, swaying angle and pitching angle co-ordinates are the modal co-ordinates. The independent influencing of the lifting, swaying and pitching movements is therefore aimed essentially at that of the modal movement components. As already mentioned, the lifting, swaying and pitching movements are modal movement components only when there is a specific relation between the spring rigidities c,, c. of the supporting springs on the front and rear axles and the axle distances a and c from the centre of gravity of the body (ac, = cc,). Only when the ratio acv/ccH is approximately equal to one can a practically effective (almost ideally) uncoupled influencing of the lifting, swaying and pitching movements be achieved. Important for the uses of the invention for vehicles is a second case., in which there is a special relation between the the [sic] mass moment of inertia IN of the body in respect of its transverse axis, its mass % and the axle distance a and c (IN = mkac). As already mentioned, this relation applies, at least approximately, to many of the present-day vehicle types. In this case, the modal co-ordinates, in addition to the swaying angle, are given by the (already above-mentioned) vertical displacements (zv and z.) of the body at the "front" and "rear". It is therefore possible and even expedient here, to influence the movement of the body at the "front" and "rear" and the swaying movement independently of one another by means of the regulation. However, for this it is necessary to employ a computing and weighting method which differs slightly from that described in Figure 2. This modified method will therefore also be explained briefly. The quantities used below can be taken from the listing under matrix (1).

1. Determination of lifting, swaying and pitching speeds (zI, alpha', beta') from measured compression movements, longitudinal and transverse accelerations (as in the exemplary embodiment already described).

2. Transformation to modal speed components: Computation of the vertical speeds of the body at points in the front and rear body region (zvl, Zh') from the determined lifting and pitching speeds zt and beta, according to:

zvr = zI - abetal Zh' = zI + cbetal 3. Weighting of the modal speed components z,l, Zh'I alpha' (swaying speed) independently of one another zvg r = gVOzVr zhgr = ghiZh' alpha. = gwalphal The weighting factors gvo, ghi and gw can advantageously be selected as dependent on quantities which represent and/or influence the driving state, such as the driving speed, braking, steering and/or accelerating manoeuvres of the vehicle and/or the ambient temperature.

4. Inverse transformation to lifting, swaying and pitching speeds: Computation of the weighted lifting 1 41 and pitching speeds z. and beta. from the weighted f modal speeds z,, and Zh, Z.1 [c/(a+c)]z-,,' + [a/(a+c)1Zhg' beta.'= -[1/(a+c)]z,,' + [l/(a+c)]Zh.' It may be noted that steps 2 to 4 can also be combined in the way described below:

Z&J, gll 0 g13 zf alpha. 0 g22 0 alpha, beta. g31 0 g33 beta' with g11 = [c/(a+c)]gvo + [a/(a+c)]ghi g13 = -[(ac)/(a+c)] [gvo - ghi] g22 = gw g31 = -[l/(a+c)] [gvo - ghil g33 = [a/(a+c)]gvo + [c/(a+c)]ghi.

In this exemplary embodiment. therefore, the system according to the invention is characterised in that, in dependence on the geometrical distribution of the mass of the vehicle and/or in dependence on parameters characterising the suspension systems, the body movements adjustable separately from one another are either - lifting, pitching and swaying movements - or swaying movements and vertical displacements of the vehicle body on the front and rear axle.

In dependence on the modal movement components, therefore, either the lifting, pitching and swaying speeds (zI, beta', alpha') or the swaying speed and the vertical speeds of the vehicle body on the front and rear axle (beta', zvI, ah') are weighted. As can be taken from the foregoing, the modal speeds of the body are therefore weighted.

In both cases in this exemplary embodiment, the weighted lifting, pitching and swaying speeds (z, J1 r beta g J1 and alpha,') appear on the output side of the 3rd filter units.

As regards a four-wheel two-axle vehicle in which active or semi-active actuators are arranged between each wheel and the body, the weighted or amplified lifting, pitching and swaying speeds (z g beta g 01 and alpha.

appearing on the output side of the 3rd filter units (3) are interlinked in 4th units (4). The transmission behaviour of the 4th units (4) can be characterised as follows in matrix notation:

F11 F12 F13 1/2 F21 F22 F23 F31 F32 F33 (5) F41 F42 F43) in which the components of the "force-distribution matrix" (5) are F11 = F21 =a2/(al+a2) F31 = F41 = al/(al+a2) F12 = -F22 = (l/bl)(ro/ro+l) F32 = -F42 = (l/b2)(1/ro+l) F43 = F33 = -F23 = -F13 = 1/(al+a2), and al is the distance between the centre of gravity of the vehicle body and the front axle, -: a2 is the distance between the centre of gravity of the vehicle body and the rear axle, -: 2bl is the distance between the points of engagement of the actuators on the vehicle body on the front axle, and 2b2 is the distance between the points of engagement of the actuators on the vehicle body on the rear axle.

The meaning of the quantity ro is explained later.

In the 4th units (4), therefore, the weighted lifting, pitching and swaying speeds (z,l, beta,,and alpha. are combined linearly, as described below.

0 fV1 F11 F12 F13 z g fvr 1/2 F21 F22 F23) (alpha.

fhl F31 F32 F33 beta. (6) fhr F41 F42 F43 The interlinkages are obtained by formal mathematics by matrix multiplication of the three-component vector (z.1, alphag', beta,') by the force-distribution matrix (5) characterising the transmission behaviour. In this case the individual filter units 21, 22, 23 and 24 can be designed as multiplication and addition units as follows, for example in accordance with the rules of vector matrix multiplication.

Unit 21: (F11z.1) + (F12alpha,') - (F13betagl) Unit 22: (F21z,') (F22alpha,') - (F23beta,') Unit 23: (F31z,') + (F32alpha,') + (F33beta,') Unit 24: (F41z,') (F42alpha,')+ (F43beta,'), the quantities Fij being defined in the way described above.

As results of the linkages, the linkage results (fvl, fvr, fhl, fhr), which represent control forces, appear on the output side of the 4th units (4). These control forces are to be seen as desired forces for the hydraulic cylinders (active system) or for the adjustable shock absorbers (semi-active systems).

The actuators are activated by means of the linkage results (fvl, fvr, fhl, fhr). By subjecting the actuators to the activating signals (fvl, fvr, fhl, fhr), control forces corresponding to the desired forces are exerted.

An especially advantageous embodiment of the system according to the invention involves using a subordinate control circuit to activate the actuators. If the activating signals (fvl, fvr, fhl, fhr) corresponding to the desired forces are linear control voltages, then the non-linear control behaviour of the shock absorber, especially of a semi-active shock absorber, is taken into account in such a way that a control force corresponding to the desired force is exerted.

If semi-active systems are used, it is necessary to determine signals which represent the relative movements between the wheel units and the body of the vehicle, and to make the shock-absorber settings by comparisons of the activating signals (fvl, fvr, fhl, fhr) with the compression movements. Furthermore, in the case of desired forces which cannot be put into practice, a maximum hard or maximum soft settings [sic) can be selected as a substitute. This can be carried out, as described, for example, in German Patent Application P 3930555.4, by taking into account the relative movements between the wheel units and the body of the vehicle, in such a way that a substitute hard or soft setting is selected in dependence on the desired force and on these relative movements.

For the physical interpretation of the forcedistribution matrix (5), it can be assumed that the relation (6) is equivalent to the equations fvl + fvr + fhl + fhr = z.11 (7a) bl(fvl-fvr) + b2(fhl-fhr) = alpha,' (7b) 11 -al(fvl+fvr) + a2(fhl+fhr) = beta. (7c) bl(fvl-fvr) - rob2(fhl-fhr) = 0 (7d).

To understand this, it is necessary merely to form the linear combinations of the forces (fvl, fvr, fhl, fhr) given in (7) and to substitute the right-hand sides of (6) for the forces themselves.

The relation (7d) can also be given in the notation ro = [bl(fvr-fvl)] / [b2(fhr-fhl)l = constit (8), in which the swaying moment of the two front control forces is seen in the numerator and the swaying moment of the two rear control forces in the denominator. The parameter ro therefore describes the rolling-moment or swaying-moment distribution (front/rear) of these forces. and the equation (8) states that the distribution is independent of time. Furthermore, its value can be selected freely in the force-distribution matrix. Thus, an adjustable swaying-moment and/or rolling-moment distribution of the control forces is obtained by the choice of the parameter ro.

For the physical interpretation of the remaining relations in (7), the movement equations Maz11 = -(fvl+fvr+fhl+fhr) + F (9a) Iwalphall = -bl(fvl-fvr) b2(fhl-fhr) + Mw (9b) Inbetall = al(fvl+fvr) a2(fhl+fhr) + Mn (9c) of the body can be considered, and in these the 11 1 1 "-sign placed after the quantities signifies the second time derivation of the respective quantity. F is the resultant of the forces which are not control forces. Such forces are those which the passive chassis components exert on the body. Furthermore, disturbance forces, etc., are also taken into account in the resultant F. Mw and Mn are the resultant moments of these forces about the swaying (longitudinal) axis and the pitching (transverse) axis. The mass moments of inertia about the corresponding axes are designated by Iw and In. The movement equations (9) are true on the model assumption that the body forms a rigid solid and for small rotations alpha and beta out of - 26 R.25249 the position of equilibrium.

If the control forces (fvl, fvr, fhl, fhr) are determined by means of the force-distribution matrix, that is to say according to the equation (6), the movement equations (9) change to the form for the regulated movement (Maz11) + (g11z1) + (g12betal) = F (10a) (Iwalphall) + (g22alphal) = Mw (10b) (Inbeta") + (g31z1) + (g33betal) = Mn (10c).

This follows directly from the relations (7) and (4).

If the task of influencing the lifting, swaying and pitching movements themselves independently of one another is considered first, then the weighting factors g12 and g31 are appropriately selected as zero. The influence of the remaining co-ordinating parameters g11, g22 and g33 is then seen clearly: for example, g 22 essentially damps only the swaying movement (a coupling with the lifting or pitching movement occurs only when the momen [sic] M, depends on these movements). The same applies accordingly to the influence of g11 and g33. That is to say, an individual damping of the lifting, swaying and pitching oscillations becomes possible.

However, if, for example, the vertical oscillations of the body on the front and rear axles of the body are to be influenced independently of one another and in a manner weighted to a differing degree, g12 and g31 must generally be selected as different from zero and all the weighting factors be suitably co-ordinated with one another.

If the proposal described for improving motoring comfort is considered as incorporated in a more comprehensive chas s is -regulating concept, it will be seen, as already mentioned above, that it is expedient to select the values of all the weighting factors as dependent on the instantaneous values of the driving-state quantities, such as driving speed and longitudinal and - 27 R. 25249 transverse acceleration. Thus, for example during braking and acceleration, g11 and especially g33 will be selected high (in comparison with g22) so as to cause the lifting and pitching vibrations occurring to die out quickly. In contrast, when the vehicle is steered into a bend, a high value of g22 (in comparison with g11 and g33) will have an advantagous effect, since the incited swaying movements are then rapidly reduced. Finally, it is possible in this way to fix a particular number of parameter sets which are assigned to specific driving situations and driving manoeuvres (characterised by value ranges of the driving-state quantities).

28 - R. 25249 Claims 1. Method for generating signals for controlling or regulating a chassis, of controllable or regulatable movement cycles, of a passenger car and/or commercial motor vehicle having at least two wheel units, wherein - first signals (Zarvl, Zarvr, Zarhl, Zarhr) representing the relative movements between the wheel units and the body of the vehicle are acquired, and second signals (aq, al) representing the longitudinal and/or transverse movements of the vehicle are acquired, and - the currently occurring modal speeds of the vehicle body are determined from the first signals (Zarvl, Zarvr, Zarhl, Zarhr) and second signals (aq, al), with characteristic quantities of the springing and/or damping elements of the suspension systems being taken into account, and - forces which are linear combinations of the modal speeds of the body are exerted by activations of the suspension systems.

2. Method according to Claim 1, characterised in that the modal speeds are influenced additively and/or multiplicatively in dependence on quantities representing and/or influencing the driving state.

3. Method according to Claim 1, characterised in that, to determine the currently occurring modal speeds of the vehicle body, the first signals (ZarvI, Zarvr, Zarhl, Zarhr) are filtered dynamically.

4. Method according to one of the preceding Claims, characterised in that 29 - R. 25249 the lifting, pitching and swaying speed of the body or - the swaying speed and the vertical speeds of the vertical body on the front and rear axle or [sic] are determined as currently occurring modal speeds of the body in dependence on the geometrical distribution of the mass of the vehicle and/or in dependence on parameters characterising the suspension systems.

5. Method according to one of the preceding Claims, characterised in that the suspension systems form springing and/or damping elements, the springing and/or damping properties of which can be adjusted continuously.

6. Method according to one of the preceding Claims, characterised in that different linear combinations of the modal speeds of the body are selected for setting a selectable rolling-moment or swaying-moment distribution of the vehicle.

7. Method according to one of the preceding Claims, characterised in that, in the case of semi-active suspension systems. a maximum hard or soft setting is selected for a desired force which cannot be put into practice.

8. Method according to one of the preceding Claims, characterised in that signals of at least one steeringangle sensor and/or signals of wheelspeed sensors and/or signals of acceleration sensors are used for acquiring the second signals (aq, al).

9. Device for carrying out the method according to Claim 1, characterised in that - first sensors (lij) are provided for acquiring the first signals (ZarvI, Zarvr, Zarhl, Zarhr) which represent the relative movements between the wheel units and the body of the vehicle, and - means (6, 7) are provided for acquiring the second signals (aq, al) which represent the longitudinal and/or transverse movements of the vehicle, and - further means (2, 3, 4, 5) are provided, by means of which the currently occurring modal speeds of the vehicle body are determined from the first signals R. 25249 (ZarvI, Zarvr, Zarhl, Zarhr) and second signals (aq, al), with characteristic quantities of the springing and/or damping elements of the suspension systems being taken into account, and by means of which forces which are linear combinations of the modal speeds of the body are exerted in dependence on the currently occurring modal speeds by activations of the suspension systems.

10. A method of generating signals for controlling or regulating a chassis, substantially as herein described with reference to the accompanying drawings.

11. A device for generating signals for controlling or regulating a chassis, substantially as herein described with reference to the accompanying drawings.