NL8901912A - Road vehicle simulator for training or entertainment - uses computer programmed with mechanical model parameters for realism - Google Patents

Abstract

The simulator can be built up from a conventional computer, VDU (52), keyboard (51), joystick (53) and special pedal board (54) or can use a specially designed console and seat which more accurately simulates a road vehicle driving position. The pedal board has spring loaded accelerator (57), brake (56) and clutch (54) pedals, while the joystick is modified to mimic a gearchange column. The signals fed to the display are under the control of a computer which has been programmed to apply a realistic computer model of the mechanical characteristics of a vehicle to the signals from the controls (53 to 57). @(34pp Dwg.No.5/7)@.

Description

Method and device for simulating the behavior of a vehicle.

The invention relates to a method and apparatus for simulating the behavior of a vehicle under the influence of variations in the controls of the vehicle, using display means to present the simulation results to a user.

Such a method is known per se. For example, computer game programs are commercially available that show a stylized vehicle on the computer's display during its execution, the speed of which can be controlled by the player using a joystick connected to the computer or otherwise.

Simulators are also known, in which the panorama is displayed on a screen that a driver of a vehicle observes as the vehicle moves through the landscape. The user of the simulator can slow down or accelerate this movement using a brake pedal and an accelerator pedal or a joystick, thereby simulating the image that a driver perceives from a faster or slower-moving vehicle.

However, none of the known methods and devices even attempt to mimic the actual behavior of the vehicle. In both cases, the player or user can only influence the speed of the vehicle. However, the player or user does not need to have any driving experience or experience in handling a vehicle such as a car, motorcycle, tractor or other vehicle equipped with an engine, clutch mechanism and gearbox.

However, there is a need for a simulator that allows a user, for example, to learn the correct handling of a vehicle without participating in traffic and without even being in a factual vehicle. Such a simulator can be used as a training device for driving a passenger car, truck, tank, earthmoving machine, etc.

Game programs are also becoming increasingly realistic and there is also a need in this area for more simulation methods that correspond to reality.

The object of the invention is now to meet this need by providing a method of the type mentioned in the opening paragraph, which according to the invention is characterized in that in a mechanical model of the vehicle a distinction is made between various moving parts of the vehicle, each of which may, to a greater or lesser degree, be coupled to other parts of the vehicle, or to the ground over which the vehicle can move, which of each of said parts is drawn up in a mathematical model by a differential equation, under the influence of said variations in the controls , the form of which depends in part on the nature of the coupling between the respective parts, other parts of the vehicle and the road, so that the behavior of the vehicle as a whole can be described at any time by a system of coupled differential equations, whereby the strength of the couplings depend on the position of the bed Controls, and that during simulation of vehicle behavior the Controls are scanned at predetermined intervals and the values corresponding to the position of these controls are used to a) determine if the system of differential equations in use is still current and b) Values determine for the corresponding parameters in the applicable system, after which, on the basis of the found solution, the said display means are controlled such that the visual presentation of the simulation results on the display means is adapted to the newly calculated situation.

The invention will be explained in more detail below with reference to the accompanying figures.

Figure 1 shows a schematic representation of a mechanical model of those parts of a vehicle which are important in connection with the invention.

Figure 2 shows a schematic representation of a mechanical model of those parts of a gearbox of interest in connection with the invention.

Figure 3 shows a number of partial views associated with the mechanical model description of the synchronization mechanisms illustrated in Figure 2.

Figure 4 shows, in simplified view, the H-shaped pattern along which the gear lever of a vehicle can generally be moved.

Figure 5 shows a perspective view of a relatively simple simulator for carrying out the method according to the invention, built up with the aid of a home computer, a video unit connected thereto and some operating elements, which are designed to simulate the operating elements of a vehicle.

Figure 6 shows a further developed embodiment of a simulator according to the invention, more suitable for professional purposes.

Figure 7 shows a general flow chart of the program that aids in carrying out the method of the invention.

In the following, a detailed description will first be given, with reference to Figures 1 to 4, of a mechanical model of those parts of the vehicle which are important in connection with the invention. A mathematical model will then be drawn up on the basis of the information obtained, various details of which will be discussed. Next, a practical form of realization will be explained with reference to Figures 5 and 6. Next, it will be discussed in detail how, during the execution of the method according to the invention in the simulator, one switches from one mathematical model to another mathematical model depending on the varying circumstances, which are simulated.

Finally, a more detailed and further elaborated embodiment of a simulator according to the invention will be further discussed.

The mechanical model

Figure 1 shows a model of a vehicle in a schematic stylized representation. On the right-hand side of the figure is the engine 1, which is supplied with fuel via a carburettor 2 from a fuel reservoir 24. The force P (g) developed by the engine 1 is influenced by the position g of the accelerator pedal 3. The crankshaft 4 of the engine 1 has a certain mass or moment of inertia K, symbolized by the mass block 5. On the other hand, crankshaft friction Z also acts on the crankshaft 4, which crankshaft friction is symbolized by a resistance block 6. The end of the crankshaft 4 is connected to the first part 7 of the clutch mechanism. The other part 8 of the clutch mechanism can be operated by means of the clutch pedal 9 by means of which the clutch between parts 7 and 8 can be made or broken. The position k of the clutch pedal 9 determines the clutch resistance C (k), which factor, as will be apparent, can be influenced by the user.

The second clutch portion 8 is connected to the synchronizing shaft 14, which also forms the input shaft of the gearbox 12. This synchronization shaft also has a certain mass in the form of moment of inertia H, symbolized by the mass block 10 and furthermore this shaft undergoes a friction D, which is symbolized by the resistance block 11. The gearbox 12 with the gears present therein, which provide a certain transmission ratio between Rotation of the input shaft 14 and that of the output shaft 15, figure 1 is shown only symbolically. The contents of the gearbox 12 and its operation, insofar as at least important for the model, will be discussed in more detail with reference to Figure 2. The position of the various elements in the gearbox 12 is influenced using the gear lever 13, which allows to change the gear ratioV (i) (i = 1, 2, 3, -, N, where N is the number of gears including the reverse gear). position).

The output shaft 15 of the gearbox 12 is coupled to the rotating parts of the vehicle undercarriage, in particular coupled to the wheels of the vehicle. On these wheels acts a moment of inertia caused by the mass M of the vehicle as a whole, which moment of inertia or mass is symbolized by the mass block 16. In order to slow down the rotation of the wheels, the vehicle is provided with a braking mechanism, symbolized by the brake pedal 18, with which a certain braking resistance R (r) can be developed depending on the position r of the brake pedal 18. Furthermore, the rotating parts of the vehicle undercarriage experience a certain friction during the movement of the vehicle. This car friction is symbolized by the resistance block 17. In addition to this car friction, which can be regarded as an internal force, the vehicle is also affected by external or external forces, such as wind or slope, which external forces E are symbolized by the resistance block 19.

In Figure 1, the various controls that the user can influence, namely the accelerator pedal 3, the clutch pedal 9, the gear lever 13 and the brake pedal 18, are schematically included in an input field 25. Furthermore, the model is provided with an output field 26 in which a number of output values for the user be made visible in some way. A first output value is the speed 20 of the engine 1, which speed is measured by means of a sensor coupled to the crankshaft 4 of the engine. A further starting value is the vehicle speed 21, which vehicle speed is determined via a sensor that is coupled to the output shaft 15 of the gearbox 12. This same sensor can also provide the necessary information for an odometer 22, with which the total distance traveled by the vehicle is recorded. In addition, there is a gas meter 23 in the output field 26 which receives information from a float system which is present in the petrol tank 24.

Figure 2 symbolically shows the most important parts of a gearbox. The example shown assumes a gearbox with three forward gears and one reverse. The gearbox is equipped with an input shaft 14, an output shaft15 and two intermediate shafts 27 and 28. The input shaft 14 is coupled to the intermediate shaft 27, because the input shaft shaft 14 a pulley 31 is mounted, on the intermediate shaft 27 a pulley 30 is mounted and both pulleys 30 and 31 are coupled together via an endless belt 32. As a result, the shafts 14 and 27 will always rotate at the same speed and in the same direction.

Similarly, the shaft 15 is coupled to the intermediate shaft 28. For this purpose, the pulley 33 is mounted on the output shaft 15 and on the intermediate shaft 28 the pulley 34. Both pulleys are coupled via the endless belt 35, with the result that also the shafts 15 and 28 will always rotate at the same speed and direction.

Two gear wheels 36 and 37 are mounted on the input shaft 14, with associated synchronization clutch mechanisms. These gears 36 and 37 rotate freely in principle around the input shaft 14. Similar gears 38 and 39 with associated synchronizing clutch mechanisms are mounted on the intermediate shaft 27. The gears 38 and 39 also rotate freely on the intermediate shaft 27. On the output shaft 15, the gears 40 and 41 mounted fixed on shaft 15 and rotating with this shaft. Gears 42 and 43 mounted on the intermediate shaft 28 are fixed to this shaft 28 and rotate with this shaft. Finally, an additional reverse gear 44 is mounted between the gearwheel 36 and the gearwheel 43 on a suitable auxiliary shaft 45.

The gear lever 13 can be moved by the user within an H-shaped track 46. When the lever is moved to one of the ends of the vertical legs of the H-shaped track, the initially freewheel gear associated with this end will be coupled to the gearbox placed in a certain gear. In the figure, the gears are indicated by the large numbers "1", "2", "3" and with the letter "R", which symbolizes the reverse position. If, for example, the gear lever 13 is first moved to the left and then upwards from the neutral position shown, then the gear wheel 38, which initially ran freely around the auxiliary shaft 27, would be coupled to this auxiliary shaft, so that the endless belt 32 would pass through the pulley 31. the pulley 30, the auxiliary shaft 27, the gear 38, and the gear 40 a fixed coupling is realized with a predetermined transmission ratio (corresponding to the first gear) between the input shaft 14 and the output shaft 15. The gearbox is thus shifted into first gear. The gears 36, 37 and 39 are still idle. Similarly, the gear can be moved to the second or third gear position or to the reverse position.

The strength of the coupling between the input shaft 14 and the output shaft 15 depends on the position of the gear lever 13 within the H-shaped track 46. If the gear lever 13 is in the neutral position shown in Figure 2, all four gears will 36, 37, 38 and 39 rotate freely and there is no question of any coupling between the input shaft 14 and the output shaft 15. If the gear lever 13 is at one of the ends of the legs of the H-shaped track 46, then there will be of a fixed or rigid clutch in one of the four gear positions. Between this fixed coupling position and the neutral position, the coupling is realized, whereby the synchronization coupling mechanisms are activated. The gearshift traverses a number of areas between neutral and fixed-clutch position, which are illustrated separately in Figure 3.

Figure 4 shows an enlarged H-shaped path along which the gear handle can be moved. In figure 4 a number of different areas are indicated, indicated with I, II and III. If the gear lever is located in area I, no gear is engaged, none of the gears 36, 37, 38 or 39 are engaged and the gearbox is therefore in the neutral position.If the gear lever is in one of the areas III, i.e. the gear lever has been moved to one of the ends of the legs of the H-shaped track, then the gear associated with that end is engaged and there is a fixed coupling between the input shaft 14 and the output shaft 15 via one of the gear combinations in the gearbox 12. If the gearbox is located in one of the areas II, the gearbox is brought from neutral position to one of the possible clutch positions or from the clutch position returned to neutral. In area II, one of the synchronization link mechanisms will be active. The operation of these synchronization coupling mechanisms will be illustrated by the schematic model shown in Figure 3.

Figure 3 illustrates what happens if one of the free-running gears 36, 37, 38 or 39 under the influence of the movement of the gears, with four consecutive views a), b), c) and d) in time. gear lever 13 is brought into the coupled position. As an example, the gear 36 located on the shaft 14 is assumed, but it will be understood that the operation of the synchronizing clutch mechanisms associated with the gear 37 on the shaft 14 or the gears 38 and 39 on the shaft 27 is identical.

The gear 36 is provided with pins that are parallel to the axis 14 and are concentrically distributed about this axis. These pins protrude from the plane of the gearwheel 36 in the direction of a clutch wheel 50. One of the said pins of the gearwheel 36 is indicated in figure 3 by 46. Between the gearwheel 36 and the clutch wheel 50 there is a spring 47. On the shaft 14 a pinwheel 48 further fixed to the shaft 14. This pinwheel is again illustrated in front view on the right side of the figure and consists of a central body from which a number of pin stitches radially.

In view a) the gear lever 13 is located in region I in which no influence is exerted on the gear 36, so that this gear 36 runs freely about the shaft 14. If the gear lever is moved in the direction of the gear 36, as in view b) is illustrated, the gear 36 is pushed to the right. Due to the presence of the spring 47, the clutch wheel 50 will also be pushed to the right until its right end face contacts the left end face of the pin wheel 48. At that time, the gearbox from area I enters area II. A slip clutch will be formed between the two end faces, the clutch strength of which depends on the degree to which the spring 47 is compressed. In view b) this coupling has just been realized and the strength of the coupling will still be small. However, if the gear lever 13 is pressed in advance, as shown in view c), the clutch wheel 50 will be pressed more and more against the pin wheel 48, thereby increasing the clutch strength. Meanwhile, the pins, such as pin 46, also move through the openings, such as opening 49, which are provided in the clutch plate 50 for that purpose. Region II is therefore characterized by varying coupling strength.

If the gearshift lever is moved even further towards its final end position, then the position as outlined in figure c) occurs just before the end position is reached. The pins, such as pin 46, now run completely through the openings, such as opening 49, in the clutch plate 50 and approach the pins of the pin wheel 48. The slip between the clutch wheel 50 and the pin wheel 48 is normally reduced to zero. As the gear lever 13 moves further to its final position, with the lever 13 leaving area II and entering area III, the pins 46 will insert into the gaps between the pins of the pinwheel 48 as shown in Figure d). This achieves the desired end position with full fixed or rigid coupling. If the synchronization mechanism cannot function correctly, for example, because the rotational speed difference between the input shaft and the output shaft is much too great (for example, if one tries to shift down from a relatively high gear directly to a relatively low gear), the ends of the pins 46 will change at the transition area II to area III do not neatly fall into the gaps between the pins of the pinwheel 48, but will be stopped by the relatively fast moving pins of this pinwheel 48. If this happens in a real car, the gearbox will as a result make a rattling noise ("brushing teeth protest).

The transition between zone II and zone III is therefore important for a computer simulation of the mechanical model shown in figures 1, 2, 3 and 4. When transitioning between zone II and zone III, the model must consider the difference between the rotational speed of the relevant shaft (14 or 27) and the rotational speed of the relevant gear (36, 37, 38 or 39). The speed of rotation of the latter gear wheel can be determined directly from the speed of the vehicle via a factor which depends on the gear wheel in operation. Only if the above-mentioned rotational speed difference falls within a reasonable range, which margin can be determined experimentally, can it be assumed that acceleration is indeed normally achieved. However, if too great a speed difference is observed, it is assumed in the model that switching on did not allow the pins 46 to slide along the pins of the pin wheel 48 with a rattling noise.

The mathematical model

The behavior of the vehicle whose mechanical model is illustrated in the above-described figures can be described by describing the behavior of the parts separately. For a sufficiently realistic model, it is sufficient to describe three main parts, which correspond to the degrees of freedom, which are used in the mathematical model to be described below. These three degrees of freedom are: 1) the rotation of the crankshaft 4; 2) the rotation of the synchronizing shaft 14 in the gearbox 12; 3) the rotation of the output shaft 15 of the gearbox. This rotation is equivalent to the position of the vehicle as a whole relative to the road surface.

Each of these three degrees of freedom has a moment of inertia and a coefficient of friction. The crankshaft moment of inertia (mass 5 in figure 1) and the crankshaft friction (resistance 6 in figure 1) act on the crankshaft 4. The sync axis has a sync axis inertia moment (mass 10 in Figure 1) and a sync axis friction (resistor 11 in Figure 1). The vehicle as a whole has its own moment of inertia (mass 16 in figure 1) and experiences frictional and external force (respectively resistance 17 and 19 in figure 1).

These three degrees of freedom can be coupled together via coupling mechanisms, the following couplings being involved: a) the crankshaft 4 can be coupled to the synchronizing shaft 14 via the coupling member 7, 8, 9, hereinafter referred to as coupling mechanism A.

b) the synchronization axis 14 can also be coupled to the degree of freedom of movement of the vehicle via the synchronization clutch mechanisms in the gearbox 12, notation: clutch mechanism B.

(c) the degree of movement of the vehicle can be coupled to the road surface via the braking mechanism 18, notation: clutch mechanism C. Each of the three clutch mechanisms A, B and C mentioned above can be in two essentially different states, namely rigidly coupled or non-rigidly coupled. Here, the non-rigid coupled state for clutch mechanism B is substantially different from the non-rigid coupled state for clutch mechanisms A and C.

In the mentioned coupling mechanisms, a distinction can be made between three cases:

Case 1) non-rigid coupling condition for the coupling mechanisms A and C:

The operation of the clutch mechanism in this state is based on the coefficient of friction of two materials in contact with each other. The two parts of such a coupling will not move relative to each other until a certain maximum frictional force between the two parts is exceeded. There is then in fact a rigid coupling as will be discussed below under case 3). Once this exceeding is the case, a force is applied to each of the two parts of the coupling equal to this maximum frictional force acting in a direction which opposes the movement of the part in question relative to the other part. here meant non-rigid coupling case.

Case 2) Non-rigid coupling condition for coupling mechanism B: This is a coupling of the so-called hydraulic type in which the force that parts to be coupled exert on each other is proportional to their speed difference and this force acts in a direction that reduces the speed difference between the coupling parts.

Case 3) Rigid coupling condition for coupling mechanisms A, B and C:

In the case of a fixed or rigid coupling, the moving parts are closely connected and can be considered as a single unit.

In the mathematical model describing the mechanical model from figures 1 to 4, the following definitions are used: C (k) = coupling resistance D = synchronizing axle friction E = external force g = accelerator pedal position H = synchronizing axle inertial moment i = gear factor index j = gear lever position (vertical) K = crankshaft moment of inertia k = clutch pedal position M = car mass P (g) = engine power q (t) = synchronization axis angle speed qq (t) = synchronization axis angle acceleration R (r) = braking resistor r = brake pedal position S (j) = synchronization s (t) = crankshaft angular speed ss (t) = crankshaft angular acceleration t = period duration u (t) = vehicle speed uu (t) = vehicle acceleration V (i) = acceleration factor W = car friction Z = crankshaft friction

As can be seen from the above list, the time derivative of a time-dependent quantity is noted by repeating the function character. In other words, the vehicle acceleration du (t) / dt is noted as uu (t), for example.

The mathematical model uses differential equations, which can describe the behavior of the vehicle under all conditions. Which combination of differential equations is needed depends on whether or not the vehicle speed is equal to 0, important for clutch mechanism C, and depends on whether the difference between the crankshaft angular speed S (t) and the sync axis angular velocity Q (t) is or is not equal to 0, which is important for clutch mechanism A. In addition, for all these cases, it is still necessary to look at the zone in which the synchronizing clutch mechanisms are located, which is important for clutch mechanism B. In particular, a distinction must be made between a situation in which the synchronization coupling is located in zone I or zone II or a situation in which the synchronization coupling is located in zone III (a situation in which there is a fixed or rigid coupling). Taking into account these conditions, 18 different situations can be described using 18 different systems of three coupled differential equations: A. Clutch mechanism A and C behave as described above as case 1): A1: Clutch mechanism B falls under case 2 described above) ( 4 cases): M.uu (t) = E -R (r) -W, u (t) + S (j). (V (i) .g (t) - u (t)) K.ss ( t) = P (g) -Zs (t) -C (k) H.qq (t) = C (k) -Dq (t) + V (i) .S (j). (u (t) - V (i) .q (t)) A2: Coupling mechanism B falls under case 3) (4 cases): (H + MV (i) .V (i)). Qq (t) = - (D + V (i ) .V (i) .W) .q (t) + C (k) + V (i). (E -R (r)) K.ss (t) = P (g) -Zs (t) - C (k) u (t) = V (i) .q (t) B. Clutch mechanism A falls under case 3) and clutch mechanism C falls under case 1): B1: Clutch mechanism B falls under case 2) (2 cases): M. uu (t) = E -R (r) -Wu (t) + S (j). (V (i), s (t) - u (t)) (K + H) .ss (t) = P (g) - (Z + D) .s {t) + V (i) .S (j). (u (t) -V (i) .s (t)) q (t) = s (t) B2: Coupling mechanism B falls under case 3) (2 cases): (K + H + MV ( i) .V (i)). ss (t) = - (Z + D + V (i) .V (i) .W) .s (t) + P (g) + V (i). (ER (r)) q (t) = s (t) u (t) = V (i) .q (t) C. Clutch mechanism A falls under case 1) and clutch mechanism C falls under case 3): C1: Clutch mechanism B falls under case 2) (2 cases): u (t) = 0 K.ss (t) = P (g) -Zs (t) -C (k) H.qq (t) = C (k) -D + V ( i) .V (i) .S (j)). q (t) C2: Coupling mechanism B falls under case 3) (2 cases): q (t) = 0 K.ss (t) = P (g) - Zs (t) -C (k) u (t) = 0 D. Clutch mechanism A falls under case 3) and clutch mechanism C falls under case 3): D1: Clutch mechanism B falls under case 2) (1 case) u (t) = 0 (K + H) .ss (t) = P (g) -z + D + V (l) .V (i) .S (j)). S (t) q (t) = s (t) D2 : Coupling mechanism B falls under case 3) (1 case):

s (t) = Oq (t) = Ou (t) = O

The equations for the situations where there is a rigid synchronization coupling are always obtained by looking for the system that has the same solution for t -> as the corresponding situation in which there is no rigid synchronization coupling, in the limit case where S (j) approaches infinity.

The above numbers of cases refer to the number of possibly different systems, which can be obtained by replacing R (r) in the described system, if they are present in the equations, by -R (r) and / or C (k) by -C ( k). This expresses, respectively, that the vehicle is in reverse or downshifted.

Generally formulated solutions can be used to find a solution of the above differential equations, appropriate to a certain combination of input variables and input constants.

In the above systems there are two types of differential equations, which in their general form can be described as follows: type 1 (separate equation): Ad / dt (x (t)) = -Bx (t) + C with solution: x (t) = a.EXP (bt) + c where: a = x (0) - C / B, b = -B / A, and c = C / Bx (0) is the value of x at time 0 (EXP (z) is e to the power z) type 2 (system of two related differential equations) Ad / dt (x (t)) = -Bx (t) + C + D. (Ey (t) -x (t )) and Fd / dt (y (t)) = -Gy (t) + H + ED (x (t) -Ey (t)) with the solution: x (t) = a.EXP ((b + g ) .t) + d.EXP ((bg) .t) + ey (t) = m.EXP ((b + g) .t) + n.EXP ((bg) .t) + q where: e = (DEH + C. (G + EED)) / (DG + B. (G + EED)) q = (DEC + Η. (B + D)) / (DG + B, (G + EED)) b = - (B + D) / (2.A) - (G + EED) / (2, F) g = SQRT (bb + DDEE / (AF)) a = (-Bx (O) + C + D. ( Ey (O) -x (O)) - (b -g) .A. (X (0) - e)) / (2.Ag) m = (-Gy (O) + H + DE (x (0) ) -Ey (O)) - (b -g) .F. (Y (0) - q)) / (2.Fg) d = x (O) - a - and = y (O) - m - q (SQRT (z) is the square root of z) (x (0 ) and y (0) are the values of x resp. y at time 0)

Thus, by substituting the correct values in the solution of these general equations, a solution can always be found for the system of equations that is valid at any given time.

The practical realization

Figure 5 shows a schematic perspective view of a possible practical embodiment of the simulator according to the invention. On a table 50 is located the computer 51, which outputs signals to a display unit 52. The computer 51 receives inputs from a number of controls, which are preferably designed to show a realistic resemblance to the controls of the vehicle being simulated. in particular, in the illustrated embodiment, the computer 51 receives signals from a gear lever 53, a clutch pedal 55, a brake pedal 56 and an accelerator pedal 57. The latter three pedals are mounted in a pedal unit 54.

The positions of the pedals and of the gear lever must be converted into computer-comprehensible data. For example, adjustable resistors can be built into pedals 55, 56 and 57, the resistance value of which depends on the position of the pedal concerned. These resistor values can then be converted into a digital number value using analog / digital converters combined with a voltage source. The gear lever 53 can be equipped with two variable resistors, with which the position of the lever in the H-profile can be accurately coded. Such operating mechanisms are known per se and a more detailed discussion thereof is therefore considered superfluous.

In many cases it will be possible to use the joystick connections on the computer, to which digital values of 8bit can be read (values varying between 0 and 255 decimal). In such a case, the simulator can be realized relatively cheaply.

As will be clear from the above discussion of the mathematical model, the clutch pedal provides an input value for the quantity C (k) depending on its position k, the brake pedal 56 provides an input value for the quantity R (r) and the accelerator pedal 57 depending on its position r depending on its position g, provides an input value for the quantity P (g).

Of the gear lever 53, in addition to the information in which arm the gear lever is located (i = 1, 2, ...), which results in a value of index i and therefore also of V (i), only the vertical displacement within the H-shape trail of interest. Depending on the vertical positionj, the gear lever 53 imposes a value for calculating the synchronization S (j). The gearbox is exposed in the horizontal part of the H-profile. A movement of the handle in this part of the profile has no influence on the behavior of the vehicle. In the following it is assumed that the value of S (j) in the freewheel region is equal to 0 and that S (j) assumes increasingly higher (positive) values the further the gear shift is from the freewheel zone.

During operation, the simulator will always be in one of the states described above. The computer 51 will each time scan the positions of the input means 53, 55, 56 and 57 at short intervals, and supplies the values for r, k, g, i and j. Within the computer, next to the value for t, the period duration between the scanning moments, must still be values are known for the vehicle mass M, the car friction W, the crankshaft inertia moment K, the crankshaft axle friction Z, the synchronization axle inertia moment H, the synchronization axle friction D and the external force E. These values can be can be entered once using the keyboard of the computer 51 at the start of the simulation process. On the other hand, the value for the external force E can also be provided, at least in part, by the program with which the landscape 58 is made visible on the display unit 52. For example, if slopes occur in this landscape, the value of E can be adjusted to these slopes.

At the beginning and / or at the end of a period, it is examined whether the present system is still applicable, as will be described further below: changing the system. For the calculation, the final values q (t), s (t) and u (t) of the previous period are now used as the initial conditions, respectively q (0), s (0) and u (0) for the current period. Subsequently, new values for q (t), s (t) and u (t) are calculated and on the basis thereof output signals are output to the display unit 52. On this display unit 52 a number of measuring instruments can be displayed which, in accordance with the indication elements 20 , 21, 22 and 23 from the mechanical model of figure 1, indicate the speed, speed, mileage, and fuel tank content, as well as, for example, a landscape content 58 including a road surface with center line. For example, on the screen of unit 52, below the landscape 58, from left to right, a clock is displayed that shows the real time (derived from the internal clock of the computer 51), a speedometer, a tachometer, and a combination of odometer and petrol pointer on the far right of each other. .

If the period t between the successive scanning moments is chosen to be short, for example a few tens of milliseconds, a smooth image is produced on the screen, which gives the user a realistic impression. The time t should be as short as possible, but should be chosen greater or equal to the maximum time that the computer 51 needs to calculate the solution of the system differential equations, the scanning of the input devices and the output of the output data.

Change of system

For the synchronization coupling, as already indicated in case 2a) above, a model of the hydraulic type has been used, because there is an analytical solution for this model, which is valid under all circumstances. For the other more realistic frictional resistance model, mentioned UNDER CASE 1), which is used for the coupling between the engine and the gearbox (elements 7, 8 in figure 1) and for the brake (element 18), there are three different solutions, each of which applies depend on the nature of the relative movement of the degrees of freedom coupled to each other by the coupling model, namely standstill, movement in an (arbitrarily chosen) positive direction or movement in a negative direction. Because the latter system has different solutions and because the synchronization coupling is rigid or non-rigid, a descriptive system must be constantly changed. For the frictional resistance model, a distinction can be made between two situations, which will be considered in detail in the following.

Situation 1:

The parts coupled via the frictional resistance model stand still in relation to each other.

In this case, forces are compared. Since the input data in the computer that is updated at the beginning of a period period can lead to a change in the forces exerted, it is in this case necessary to test whether it is still justified to work with a model based on a mutual standstill of the degrees of freedom relative to each other.This test amounts to testing whether or not an inequality is true, which is obtained in the following way:

Determine which of the two coupled parts has the greatest moment of inertia and establish the inequality for this part. The part with the greatest moment of inertia is chosen because this part is less likely to undergo a large speed change. In the case of the coupling between the vehicle and the road, the road surface will be chosen for this and the determination of the acceleration of the road surface is simple in this case, this acceleration is of course equal to 0. In the case of the coupling (parts 7, 8, 9 in the model of figure 1) the acceleration undergone by the two coupled parts is calculated for the starting time of the present period. In the applicable mathematical model u (0), s (0) and q (0), i.e. the initial conditions at t = 0, are substituted for this; these initial conditions are equal to the final values calculated in the previous period. Multiplication of the gear found in this way by the moment of inertia associated with this part yields the sum of the forces applied to this part (for the brake this sum will be 0). Subtracting from this sum all the forces exerted on it, except that of the force (to be tested) by the coupling transmitted, then an expression of the force just mentioned by the coupling transmitted arises. It can now be compared to the frictional resistance of the coupling to test whether this frictional resistance is exceeded. There is a test for an overshoot to be followed by a movement, where the speed difference between the coupled parts takes position values and a test to be followed by negation values.

Similarly, using the various systems of differential equations, the following inequalities are obtained: A. In case u (t) is equal to zero and (s (t) -q (t)) is equal to zero: (in this case, the coupling tested) a. synchronization coupling not rigid:

(K + H)

Sub in the inequality: K.ss (O) - P (g) + Ζ.ε (0)> C (k) followed by positive values of a (t) -q (t), K.ss (O) - P (g) + Zs (0) <-C (k) followed by negative values, b. synchronization link rigid:

In case u (t) is negative, in the above expression R (r) should be replaced with -R (r).

Inequality: K.ss (O) - P (g) + Zs (O)> C (k) followed by positive values, K.ss (O) - P (g) + Zs (O) <- C (k) followed by negative values.

B. in case u (t) is zero and (s (t) -q (t)) is not equal to zero: (in this case the brake is tested) a. Synchronization clutch not rigid:

Inequality: S (j) .V (i) .q (0) + E> R (r) followed by positive u (t), S (j) .V (i) .q (0) + E <-R (r) followed by negative u (t).

b. synchronization link rigid:

Inequality: {V (i) .E + C (k)} / V (i)> R (r) followed by positive u (t), {V (i) .E + C (k)} / V (i ) <-R (r) followed by negative u (t).

In case s (t) -q (t) is negative, in the above two inequalities C (k) should be replaced by -C (k) C. In case u (t) and (s (t) -q (t)) both are equal to zero: in this case both clutch and brake are tested.

First of all the test of the coupling, a. Synchronization coupling not rigid: ss (0) = {P (g) - (Z + D + V (i) .V (i) .S (j)). S (0) } / (K + H)

For the inequality: P (g) -Zs (O) -K.ss (O)> C (k) followed by positive values, P (g) -Zs (O) -K.ss (O) <-C ( k) followed by negative values.

b. synchronization link rigid:

Inequality: P (g)> C (k) followed by positive values, P (g) <-C (k) never occurs since P (g) is always positive, then the braking force overrun test, c. synchronization coupling not rigid:

Inequality: S (j) .V (i) .q (0) + E> R (r) followed by positive u (t), S (j), V (i) .q (0) + E <-R (r) followed by negative u (t).

d. synchronization link rigid:

Inequality: {P (g) + V (i) .E} / V (i)> R (r) followed by positive u (t), {P (g) + V (i) .E} / V (i ) <-R (r) followed by negative u (t).

If the test under b shows that P (g)> C (k) then the above two inequalities should be replaced by: {C (k) + V (i) .E} / V (i)> R (r) followed by positive u (t), {C (k) = V (i) .E} / V (i) <-R (r) followed by negative u (t)

The left-hand side of the inequalities in each case represents the force exerted by either the coupling (the connection via parts 7 and 8 between the crankshaft 4 and the synchronizing shaft 14) or derem (the connection of the translational degree of freedom of movement of the vehicle with the road surface) . If the inequality is true, the maximum frictional force of the clutch or brake is exceeded and the descriptive model must be changed.

In case C above (where u (t) and (s (t) -q (t)) are both equal to zero), both the inequality of the clutch and that of the brake must be tested before deciding on which descriptive model to pass. As mentioned, the comparison between the forces takes place at the beginning of a period. If the power overrun occurs somewhere in a period, the computer can only respond to it after the next scan time and therefore an error will occur. This error decreases the shorter the period can be chosen. For the user, this error could be described as the "sticking" of the clutch or brake.

Situation 2.

The parts coupled by means of the frictional resistance model show a mutual movement. In this case, since this relative movement changes within the period duration t, it should be tested at the end of such a period whether the descriptive mathematical model, valid at the beginning of the period, is still valid. Since the input data of the computer retrieved at the beginning of the period is considered to be constants during the period and because all solutions belonging to the frictional resistance model have a monotonous decreasing or increasing character, it can in any case be assumed that the direction of movement of the individual parts of the model have not changed during the period itself. The test at the end of the period can be easily performed by checking if the relative movement at the end of the period has changed direction (mathematically from sign). If the direction has indeed changed then there are two questions that need to be answered: 1) At what point during the period did the linked degrees of freedom pause relative to each other? 2) What was the speed of the degrees of freedom at the moment found under 1)? (for coupling the degree of freedom of movement of the vehicle with the road surface via the brake, this speed is equal to 0).

To answer these questions, an imprecise approximate method can be used without objection. Although inaccuracies are introduced because of this, these inaccuracies are so small that they are not disturbing to a user, while, moreover, such changes occur relatively sporadically. For example, it may be a bit more rough to forget the above question 1), namely the question at which point in the period when the standstill occurred, and to immediately start a new period with the new model. In that case, hardly any attention is paid to the synchronization in time.

In the new model, the coupling must then be replaced by a rigid coupling, taking, for example, the initial speed of the now rigid coupling parts as the speed of the part with the greatest moment of inertia at the beginning of the period just terminated prematurely. A more accurate approximation for this speed would be to take the speed at the time of the relative standstill, which speed can then be approximated linearly. In that case the formula for the linear approximation below would be used with the note that higher order approximations are of course also possible:

where: t = period duration x (0) = speed of part 1 at time 0 y (0) = speed of part 2 at time 0 x (t) = speed of part 1 at time ty (t) = speed of part 2 at time tt '= the moment of intersection of x and y (ie standstill) (t * = (x (0) -y (0)). t / (x (0) —y (0) -x (t) + y (t))).

As mentioned above, the small error (maximum equal to a period duration) in the determination of time will have little effect on the user.

A number of variants are possible for the aforementioned handling of the model change, such as not terminating the period prematurely, but waiting until a full duration t has elapsed or, as already mentioned, making higher order approximations of the starting speed of the coupled part. The said t 'can also be taken into account in the synchronization over time, but no significant improvement of the simulator is expected by such variants.

Further developed embodiment

In order to make the simulator more interesting for the user, it is preferable that the environment in which the simulator functions is better adapted to reality, in other words, the simulator should preferably be placed in such an environment that the user of the simulator actually gets the feeling to be in a vehicle and to drive this vehicle. In the first place, it is therefore preferable to add a steering wheel to the operating elements, which steering wheel can also supply input data to the computer, which can thereby control the landscape background. The use of such steering wheels and their coupling with a program for generating a background landscape is known per se, so that it is not necessary to go into further detail.

A possible very realistic arrangement of the simulator, particularly suitable for professional use, is schematically illustrated in figure 6. In figure 6, the simulator is built up within a housing 60, which at least provides the atmosphere in the driver's seat for the user who is in the seat 61. mimics a vehicle. The simulator is again provided with an accelerator pedal 62, a brake pedal 63 and a clutch pedal 64, as well as with a gear lever 65. Furthermore, there is already added input means 66 with handlebar. The output means here again consist of a screen unit, for which in this case a television projection unit with a large screen 67 has been chosen. The actual projectors, which incidentally are prior art, may be arranged within the housing 60 at the rear of the screen. screen 67. On the dashboard 68 the combined speedometer / odometer 69, the tachometer 70 and the petrol meter 71 are located in a usual location. In this embodiment, these measuring instruments are not realized in software, as in the embodiment of figure 5, but are as separate measuring instruments built into the dashboard 68 and as such are controlled through a suitable output port of the computer. Whether this method of presentation is chosen or a completely software-controlled presentation on the screen, as shown in figure 5, does not make any difference for the invention. The simulator further includes the keyboard 72 which, in this case, is mounted on the side of the housing 60 in a location accessible to an operator or instructor, while optionally installing an auxiliary screen 73 on which the operator has either the same image as shown on the screen 67, or optionally in another manner, can communicate with the computer located in the housing 60 via the keyboard 72.

For applications such as learning to operate a vehicle with a manual transmission or as a skill entertainment game, a relatively simple landscape content such as a center stripe road surface which forms a simple closed circuit can be satisfied.

It may even suffice to use a map of the circuit, which is covered by the vehicle. However, in a more realistic embodiment as in figure 6, it is preferable to also give the landscape projection a more realistic character. However, projecting such realistic and vehicle-moving landscapes is well known in the art and does not form part of the invention.

A further contribution to make the simulator appear more realistic can be obtained by installing a sound source in the housing 60, which sound source is also controlled by the computer not visible in figure 6. Depending on the momentary situation in which the simulator is located, this sound source produces a sound which, depending on the engine speed, corresponds to the sound perceived in an actual vehicle. In addition, this sound source can be used to simulate any shift signals at times when the gear lever 65 is operated.

Preferably, the sound source is further provided with possibilities to realistically let the wrong switching be heard by under-controlling the computer by reproducing a "teeth grinding" sound.

It is preferable to build in a start button in the simulator, with which the engine of the vehicle can be started, as it were. The engine "starts" as soon as a predetermined speed is exceeded by the crankshaft rotation. The engine will also have to "stall" if the speed drops below a certain speed. This situation may arise, for example, if the user brakes without shifting the engine into neutral. If the braking continues until the vehicle has almost stopped, the engine will also stop. For P (g), when the engine is not running, there is a minimum value even if the accelerator pedal is fully released. This minimum value can be set using the software and changed if necessary. This minimum value of P (g) normally ensures that the engine can remain idle.

The values of P (g) can be summed by means of numerical integration and thus an indication can easily be obtained of the fuel consumption. If a fuel gauge 71 is present, it can be easily controlled on the basis of the calculated summation values.

A simulation of the parking brake can be added in the form of an additional contribution to the braking resistor R (r). In that case, a handbrake lever will have to be installed in the simulator, which is also periodically queried by the computer to determine the position of the handbrake. If a handbrake simulation is applied, then in mathematical models only the term R (r) needs to be replaced by R (r) + HR (r '), where HR (r') is the handbrake resistance and r 'is the position of the handbrake lever.

Figure 7 shows in the form of a flow chart the main functions which are performed within the simulator under software control by the computer. After the software has started in the START block 80 with u (t) = s (t) = q (t) = 0 and set with the flags A and C, the latter means that the coupling mechanisms A and C are in the rigid state, the program will cycle through the large loop shown in this figure. In block 81, the flag Q is reset, the function of which is discussed later, and the internal computer clock is set to 0.

Thus, at a given point in block 82, the input data E, g, r, k, j and i will be retrieved, as well as an input data corresponding to whether or not the starter motor switch is pressed. It is this last input that determines in the next block 83 whether flag S is set.

The magnitude of the speed s (t) in relation to the previously described speeds of the crankshaft, above or below which the engine * runs or has stalled, determines whether or not flag N is set in block 84.

Directly from the input regarding the vertical position of the gear lever it can be deduced whether or not flag B should be set in block 85, this corresponds to whether or not coupling mechanism B is rigid. For this coupling mechanism, the transition from non-rigid to rigid clutch it remains to be tested whether the difference in rotational speed of the parts to be coupled is sufficiently small, as described in the "the mechanical model", which amounts to a test for the so-called "teeth brushing of the gearbox.

In addition, a test can be built in to check whether the forces exerted by the coupled parts on each other are sufficiently small to permit a transition from rigid to non-rigid coupled condition (the inequality to be tested can be obtained in an analogous manner as described under "change system"). "," situation 1 "). It would be very realistic to provide a computer-controlled mechanical device that could block the passage of the gearshift lever in the "H-profile" if necessary.

Next, in block 86, it is checked whether one or both of the clutch mechanisms A and C are in the rigid state, which is then followed by a situation-appropriate test and further handling.

This further processing takes place in blocks 87, 88 and 89, testing the inequalities described under "change of system, situation 1" under A, B and C. respectively.

Before the actual tests are carried out in these blocks, a distinction must still be made on the basis of flag B for the situation with coupling mechanism B rigid or non-rigid. For block 87, a distinction must also be made for a movement u (t) in positive or negative direction as soon as there is a rigid coupling mechanism B. For block 88, a distinction must be made between positive and negative s (t) -q (t) also once a rigid coupling mechanism B is in use.

There are tests that, if the condition is met, are followed by a positive movement and tests followed by a negative movement, where flags can be set that express these different directions of movement.

To simulate the operation of a starter motor and of the engine stop or stop mechanisms, replace all of the inequalities just discussed, but also in the formulas for the solutions to be calculated in block 90, P (g) with : "p (g)", if flag N is set and flag S is reset; by: "0", if both flags N and S have been reset; by: "P (g) + starter motor force" if both S and N have been set and by: "starter motor force" if S have been set and N has been reset.

Then follows block 90 where, depending on the state of the flags S, N, A, B and C, as well as flags mentioned above for the directions of movement, the applicable system is selected and resolved. Here the (old) values of u (t), s (t) and q (t) now become the (new) initial conditions u (0), s (0) and q (0) and then the new values for u ( t), s (t) and q (t) calculated.

In case coupling mechanism A is not rigid, in the test section associated with block 91 it is checked whether a change of direction of movement has occurred for the newly calculated values of u (t), s (t) and q (t). Such a test is discussed under "change of system, situation 2" and if the tested condition is met, flag A must be set, so that again there is a rigid coupling mechanism A, moreover, in such a case, the flag Q must still be set .

This flag Q just mentioned will cause a new cycle to commence without further loss of time later in block 93.

Block 92 is analogous to block 91, but for the coupling mechanism C.

Block 94 takes care of the synchronization in time by waiting in a waiting loop for the moment when the computer clock indicates that one period duration t has elapsed.

Finally, in block 95, the output data to be displayed is updated and block 81 is resumed, and input data is retrieved in block 82, etc.

Although it has already been generally indicated above in which way a solution can be found for the systems of differential equations, use is preferably made of a number of tables in which pre-calculated values, which may be necessary during the simulation process, are stored. In connection with this it should be noted that the parameters dependent on the input members, with the exception of S (j) and V (i), are found in the final solutions only in the form of coefficients. Thus, these parameters do not appear in the expressions, which are the parameters of the exponential functions present. The same applies to the boundary conditions u (0), q (0> and s (0), which also only occur in the form of coefficients, which means that all solutions can ultimately be rewritten to the following general form: x (t) = c1.x (0) + c2.C (k) + c3.R (k) + c4.P (g) + c5.y (0)

Here c1 to c5 are functions of the parameters V (i), S (j), M, W, t, x (0) and y (0) stands for u (0), q (0) or s ( 0), x (t) and y (t) stands for u (t), q (t) or s (t).

The inequalities noted above and intended to determine whether to change models can be treated in the same way and therefore lead to a relatively simple form.

The consequences of this are that tables can be used, in which all possible values for the mentioned coefficients c1, c2, c3, c4 and c5 can be entered. Correctly addressing these tables then leads directly to a value for the relevant coefficients. For example, if it is assumed that index i is chosen with i = 1, 2, ...., 5 and that j can take discrete values with j = 1, 2, _____ 128 then there should be five times 128 possible values per c1, c2 , .... c5 are stored in the table. This table can be calculated in advance and functions during the actual simulation processes only as a look-up table in which current values can be looked up, which only need to be multiplied by x (0), C (k), R (k), P (g) and y (0). A simple addition then results in the new values of u (t), q (t) and (t). Although additional memory space is required on the one hand for storing the tables, it has been found in practice that this memory space fits within the space available in the usual microcomputers. The time gains that can be realized by using the tables and thus the reduction of the period duration t will generally outweigh any additional memory capacity required.

Claims (3)

Method for simulating the behavior of a vehicle influenced by variations in the controls of the vehicle, using display means to present the simulation results to a user, characterized in that in a mechanical model of the vehicle a distinction is made between various moving parts of the vehicle, each of which, under the influence of the said variations in the controls, may be coupled to a greater or lesser extent with other parts of the vehicle, or with the ground over which the vehicle can move, that of each of the said parts in a mathematical model a differential equation is drawn up, the form of which depends partly on the nature of the coupling between the relevant part and other parts of the vehicle, respectively the road, so that the behavior of the totality of the vehicle can be described at any moment by a system of coupled differential equations, in which the strength of the couplings depends on the position of the controls, and that during the simulation of the behavior of the vehicle the controls are sensed at predetermined intervals and the values obtained corresponding to the position of these controls are used to determine a) or the system of differential equations is still current and b) determine values for the corresponding parameters in the applicable system, after which, based on the solution found, said display means are controlled such that the visual presentation of the simulation results on the display means is adapted to the newly calculated situation. Method according to claim 1, characterized in that the named parts of the vehicle which are considered separately within the mechanical model and which in the mathematical model in the form of variables form part of at least one system of differential equations consist of: the moving part of the drive motor with the related part of the clutch, the other part of the clutch and the parts of the gearbox moving in fixed relationship, including part of the synchronization mechanisms in this gearbox, the other part of the synchronization mechanisms and the parts of the gearbox associated therewith, respectively of the vehicle chassis. Method according to claim 1 or 2, characterized in that the partial calculations to be performed in solving the system of equations and resulting in a value belonging to a relatively limited group of values are replaced by a lookup step in a table, wherein all possible values belonging to the said group are stored in this table in such a way that this table, addressed by the discrete digitized values of the variables, for which partial calculations must be performed, yields the correct starting value.