JPH09207623A - Control or limiting method and device for vehicle speed - Google Patents

Abstract

PROBLEM TO BE SOLVED: To sufficiently reach a prescribed speed under any driving condition by varying the gradient of a control target value fed to at least one controller on the basis of the actual value existing when the controller is actuated and a prescribed target speed. SOLUTION: A speed target value varying timewise, or in other words, a speed characteristic curve is fed to a controller 36 as a target setting value and the gradient of the speed characteristic curve is the function of the prescribed target speed and the speed difference. Thus the controller 36 piles an additional setting valve ion an auxiliary control. The control target speed varying timewise is formed within a calculation element 28 where the gradient of the target value characteristic curve is determined on the bases of the prescribed target speed and the speed difference. The actual acceleration of a vehicle deteriorates by the controller 36 actuating. At this point of time, the actual speed actuates a speed controller which is for maintaining the prescribed target speed. The actual speed exists within a range near the prescribed target speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle speed control or limiting method and device.

[0002]

2. Description of the Prior Art A method of this kind or an apparatus of this kind is known from DE 3510174 (US Pat. No. 474).
7051). Here, a traveling speed controller is described in which a speed controller is operated to maintain a predetermined speed in a steady operation state, and an acceleration controller is operated in a dynamic operation state when approaching a predetermined speed. There is. The acceleration controller operates based on a signal indicating the acceleration of the vehicle derived from the traveling speed. This signal must be strongly filtered so that the actual acceleration curve is smooth. This causes a large delay in the control at the same time, so that in all cases it is not possible to reach the desired speed sufficiently. Furthermore, in order to make the transition from one controller to another sufficient, the integral component of the controller is set when transitioning to a particular value. In this case, an expensive algorithm must be used for the activation and initialization of the destination controller, which will likewise affect the reaching of the target value.

From German Patent Publication No. 2842023
There is known a traveling speed controller that is provided with a control target value that changes with time in order to make the actual speed reach the target value. In this case, this control setpoint is formed in the form of a curved curve with a predetermined slope, which takes a predetermined fixed value, possibly given as a function of the difference between the target speed and the actual speed, by the driver. Is a function of the difference between the given target speed and the time-varying control target speed,
Or it is a function of the difference between the control target value and the actual value which change over time. However, this method does not achieve sufficient target values in all cases unless expensive algorithms are used.

[0004]

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a control or limitation of the vehicle speed which makes it possible to reach a predetermined speed sufficiently in all driving situations.

[0005]

SUMMARY OF THE INVENTION In a vehicle speed control and / or control method and device for adjusting a vehicle speed according to the invention, at least one controller for setting a setting element affecting the speed is temporally related to the running speed. A varying control objective value is given. At least one controller adjusts the vehicle speed in a direction that brings the vehicle speed closer to the control target value. In this case, the gradient of the control setpoint value supplied to the at least one controller is changed on the basis of the actual value and the predetermined setpoint speed which are present when the controller is activated.

[0006]

1 shows an overall block circuit diagram of a first embodiment of the method according to the invention. Here, an operating element 10 for setting a predetermined target speed or speed limit, which can be operated by a driver, is shown, which operating element 10 is connected via a line 12 to a memory element 14.
From the memory element 14 a line 16 leads to a coupling stage 18 for forming the deviation between the predetermined target speed and the actual speed. The coupling stage 18 is fed by a line 20 from a line 22, which emerges from a measuring device 24 for measuring the vehicle speed. Output line 26 of comparison element 18
To the calculation element 28, in which the time-varying control target speed Vsoll * is calculated as a function of the difference ΔV between the predetermined target speed Vsoll and the actual speed Vist. Furthermore, from line 16 to calculation element 28
Line 17 leads to. Other input line is line 2
9 and line 29 emerges from line 48, which will be described later, to activate and deactivate computing element 28. The output line 30 of the computing element 28 leads to the comparison stage 32, and the output line 34 of the comparison stage 32 leads to the controller 36. This controller 36 represents a controller for dynamic operating conditions (leading to a predetermined target speed). Therefore, this controller is also called an acceleration controller. The output line 38 of the controller 36 leads via a switch element 40 to a coupling stage 42, and the output line 44 of the coupling stage 42 leads to another coupling stage 46. In this case, the switch element 40
Are switched by the release element 50 via the line 48. A line 52 is supplied from the characteristic curve group element 54 to the coupling stage 42, a line 16 to a line 56 and a line 58 are supplied to the characteristic curve group element 54, and the transmission of the vehicle is actually turned on via the line 58. The traveled gear (actual gear) is transmitted. Similarly, a line 60 is supplied to the coupling stage 46, and the line 60 is connected to the characteristic curve group element 6
2 leads to the coupling stage 46. In the characteristic curve group element 62, a line 66, which is output from a line 68 described later,
And a line 70 emerging from line 58 is supplied. The output line 72 of the coupling stage 46 leads via a switch element 74 to a selection element 76, the output line 78 of the selection element 76 leads to a setting element 80 for adjusting the vehicle speed, preferably a throttle valve. The switch element 74 has a line 72
Besides, a line 82 is supplied from the controller 84, and a line 86 to a line 86 is supplied to the controller 84. The controller 84 controls the speed in a steady operation state, and therefore the controller 84 is also called a speed controller. Switch element 74 is operated via line 80,
Line 88 also diverges from line 26. Further, the line 90 is supplied to the selection element 76, and the line 90
Is an output line of the characteristic curve group element 92. The characteristic curve group element 92 is provided with a line 94 from a measuring device 96 for measuring the position of the accelerator pedal which can be operated by the driver. Further, a characteristic curve group element 98 is provided, and the characteristic curve group element 98 has a line 10 extending from the line 26.
0 is supplied. In the characteristic curve group element 98, the target acceleration Asoll is determined as a function of the difference ΔV between the predetermined target speed Vsoll and the actual speed Vist, and the target acceleration is supplied to the comparison stage 102 via the line 68. The output line 104 of the comparison stage 102 leads to the release element 50. In the comparison stage 102, line 1 from the differentiation stage 108 for forming the actual acceleration Aist of the vehicle
06 is supplied. This differentiation stage 108 has a line 22
From the line 110. In addition to the line 104, the release element 50 is further supplied with lines 90 to 112, lines 52 to 114, and lines 60 to 116.

The embodiment shown in FIG. 1 shows a vehicle speed limiter in which a controller 36 is actuated in the direction of acceleration control in order to bring the speed to the speed limit.
When the predetermined target speed is reached, the controller 84 is activated in the direction of speed control. Switching is performed between both controllers (by the switching element 74) as a function of the difference ΔV between the predetermined target speed Vsoll and the actual speed Vist. In the preferred embodiment, the controller 84 itself is activated when the speed difference falls below a predetermined speed difference which is substantially greater than the speed difference used to switch from the controller 36 to the controller 84. . In order to improve the control characteristics, a preliminary control of the controller 36, which is indicated by the characteristic curve group elements 54 and 62, is additionally performed. The first preliminary control value VW1 is formed in the characteristic curve group element 54 as a function of the gear position and the predetermined target speed Vsoll. The second preliminary control value VW2 is the characteristic curve group element 6
2 is determined as a function of the target acceleration Asoll and the input travel stage. In this case, the preliminary control is performed on a flat road and in an unloaded vehicle. This means that, in the ideal case, only a preliminary control for the acceleration of the vehicle is sufficient, so that the controller 36 only needs to control the deviation from this ideal setting. . In this case, the preliminary control values VW1 and VW2 are superimposed on the output line of the controller 36 in the coupling stages 42 and 46 and are preferably added. Further, the preliminary control values VW1 and VW2 are supplied to the release element 50, which determines the start condition of the controller 36 and the start condition of the characteristic curve (ramp) of the control target value in the calculation element 28. The controller 36 and its precontrols 54 and 62 or the speed controller 84 generate a setpoint value for setting a setting element 80 which influences the speed. In this case, the respective setpoint value is supplied to the selection element 76, which forms the respective control setpoint value as well as the minimum of either setpoint value derived from the accelerator pedal actuation via line 90, Set value further 8
Supply 0. The setpoint value for the driver is determined in the characteristic curve group element 92 as a function of the degree of actuation of the accelerator pedal and, optionally, as a function of other operating variables such as the engine speed.

In the preferred embodiment, controller 36
Is used as a simple proportional controller. In this case, the amplification factor of the proportional controller is a function of the input running stage.

As a target set value, a speed target value that changes with time, that is, a so-called speed characteristic curve (ramp) is a controller 36.
, The slope of this velocity characteristic curve is a function of a given target velocity and velocity difference. This causes the controller to superimpose additional setpoints on the preliminary control (positive or negative). A time-varying control target velocity is formed in the calculation element 28,
In the calculation element 28, the gradient of the desired value characteristic curve is determined on the basis of the predetermined desired speed and speed difference.

The characteristic curve obtained by the calculation element 28 is formed up to a range in which the speed difference decreases so that the speed controller can be switched. This means that in terms of control technology, a variable I component is formed in addition to the proportional component of the controller 36. In this case, the slope of the characteristic curve becomes flatter as it approaches the predetermined target speed. Therefore, the purpose of the preliminary control is to carry out on a flat road and on an unloaded vehicle.
The characteristic curve is longer.

In the preferred embodiment, the characteristic curve of the control setpoint and the set signal of the controller 36 are determined only under the specific conditions tested by the release element 50. The release element 50 releases the controller 36 and the characteristic curve when the driver makes a setting via the preliminary control, i.e. when the driver wishes to set a speed above a predetermined target speed. For this reason, the release element 50 has
Preliminary control values as well as driver settings are supplied.
If the setpoint value SolF of the driver is greater than the sum of the preliminary control values VW1 and VW2, the switch element 40 is closed and the calculation element 28 is activated. As a function of the input signal of the controller 36, the controller 36 modifies the pre-control value so that the setting element is such that the setpoint value SollR formed from the controller 36 and the pre-control value is the set value Soll of the driver.
As long as it is smaller than F, it is set based on this target value SollR. In this case, the characteristic curve of the control setpoint starts from the actual speed present at the time of actuation, so that at the time of start, the control deviation of the controller 36 is zero.
It is. Therefore, no initialization routine is needed.

If the driver releases the accelerator pedal, that is, if the driver's setpoint falls below the pre-control, that is, the controller 36 and the setpoint for the precontrol SollR again exceed the driver's setpoint SolllF and the set element 80.
If is set as a function of the driver's target value SolLF, the formation of the characteristic curve is stopped. Then, if the target value of the driver again exceeds the target value of the controller, the formation of the characteristic curve is restarted from the stopped value. In this case, the set value of the controller 36 is set to the value before the interruption. Driver is 50% of (maximum throttle valve opening)
When the target value of is set, the preliminary control becomes 35% (a steep slope), at which time the controller 36 opens to 15%. At this time, the characteristic curve is interrupted. Then, if the driver further depresses the accelerator pedal to, for example, 70%, the characteristic curve of the controller 36 starts at a value of 50% and reaches a maximum of 70%.
To rise. If the driver does not pedal to 70% and returns to 40%, the characteristic curve and controller 36 will start from this 40%. However, if the setting value of the driver drops below the preliminary control,
The next time a switch-on condition is present, the characteristic curve and controller 36 are restarted from zero. The lines required to carry out this function, which supply the actual speed to the calculation element 28 and the lines required to set the starting value of the controller 36, are shown in FIG. 1 for the sake of clarity. Not not.

Another switch-on criterion for the controller 36 and the characteristic curve is acceleration. The actual acceleration of the vehicle is
When it is greater than the target acceleration given as a function of the speed difference, the controller 36 and the characteristic curve are started. By this means, when the driver's set value is always under the preliminary control (such as when the vehicle is going down a slope) (the controller 36 is not operated because the preliminary control is larger than the driver's set value), the traveling speed is set to a predetermined value. It is prevented that the speed is increased above the target speed. Therefore, the controller 36 (and the target characteristic curve) is started when the target acceleration is exceeded in order to prevent speed overswing.

An example of the operation of the method according to the invention is shown in FIG.
2c. Here, FIG. 2a shows a time diagram of the set value SollF by the driver and the set value SollR by the controller 36 (+ preliminary control), and FIG. 2b shows a time diagram of the target acceleration ASoll and the actual acceleration Aist, and FIG. 2c shows a time diagram of the actual speed Vist and the predetermined target speed Vsoll or control target speed Vsoll *. The travel speed limiter is activated, ie the speed limit V given by the driver
It shall be assumed that the difference ΔV between the soll and the actual speed Vist is smaller than the limiter activation threshold. First, the vehicle is accelerated on the basis of the target value SolllF given by the driver, which is smaller than the target value calculated by the preliminary control of the controller 36. At time T0, the operating criteria of controller 36 are met. At time T0, the actual acceleration Aist exceeds the target acceleration Asoll. This means that after the time T0, the control target speed Vsoll *, which changes in a characteristic curve, is given to the controller 36. Next, the controller 36 controls the control target speed Vs.
On the basis of the difference between oll * and the actual speed Vist, the pre-control value and thus SollR is modified. Time point T0 '
At the control setting value SollR calculated from the preliminary control and the control value at the value Soll given by the driver
Below F, the setting element is set as a function of the control setpoint SollR. The actual acceleration of the vehicle decreases until time T1 due to the operation of the controller 36. At this point, the actual speed is within a range close to the predetermined target speed that activates the speed controller to maintain the predetermined target speed. At time T1, the controller 36 and the formation of the characteristic curve are stopped. Set value Sol by preliminary control
Although the 1R is formed again, this setpoint SolllR is not adjusted after the time T1 since the setpoint is set as a function of the speed controller (or the setpoint of the driver). From FIG. 2 it is clear that the method of the present invention allows the actual speed to reach the target speed sufficiently without incurring any great expense.

FIG. 3 shows a second embodiment of the method according to the invention. This differs from the embodiment shown in FIG. 1 in the following points. Descriptions of like elements used in both embodiments are omitted. In the second embodiment shown in FIG. 3, a controller (PI controller) 36 'having a proportional component and an integral component is used for the controller 36. This control deviation is formed in the filter element 200 from the control target speed Vsoll * adjusted in time and the actual speed Vist measured. In this case, the filter element 200 is supplied directly, on the one hand, with the line 16 from the memory element 14 of the desired value and, on the other hand, with the actual speed Vi.
A line 20 is provided which carries st. All other elements correspond in their function to the elements of the first embodiment. In the filter element 200, starting from the current vehicle speed, a predetermined target speed is supplied to the comparison stage 32 via the filter. This filter is
In the preferred embodiment, it is a primary filter, the so-called PT1 filter. In this case, the time constant of the filter is a function of the velocity that exists when the controller 36 'is activated. In other advantageous embodiments, other filters have also proven suitable. It is important that the filters used include at least one first-order delay. The controller 36 ', in order to maintain steady accuracy,
It is designed as a controller with proportional and integral components. The process of reaching a given target speed is set using a filter time constant which is a function of speed in the preferred embodiment. Therefore, at high speeds it is considered that the acceleration capacity of the vehicle is reduced. The switch closing conditions for the controller 36 'and the control target value setting correspond to the switch closing conditions of the embodiment shown in FIG. This is because controller 36 'and filter element 20 are present when any switch-on condition exists within release element 50.
0 means that it is activated. The predetermined target speed stored in the memory element 14 starts from the actual speed at that time and uses the time constant as a function of the actual speed at that time, which is the control target speed Vsol on which the control is based.
filtered to l *.

An example of the process of reaching a predetermined target speed is shown in FIG.
Is shown in Here, FIG. 4a shows the setting value SollF by the driver or the setting value SollF by the controller 36 '.
The time diagram of R is shown. FIG. 4b shows a time diagram of the actual speed Vist, the predetermined target speed Vsoll and the filtered control target speed VSoll *. In this case as well, it is assumed that the vehicle is likewise accelerated to time T0 based on the target value given by the driver. The target value SollR of the controller 36 'is determined by the preliminary control of the controller 36' in this operating process. At time T0, the set value of the controller 36 'falls below the set value of the driver, that is, the sum of the preliminary control value and the set value So of the driver.
It is assumed that it is smaller than 11F. This means that at time T0 the controller 36 'and the filter have been activated. Therefore, after the time point T0, the filtered control target speed Vsoll * is guided from the actual speed Vist at the time point T0 to the predetermined target speed Vsoll based on the filter time constant. Controller 3
6'forms a correction signal for the preliminary control on the basis of the difference between the control target speed Vsoll * and the actual speed Vist so that at time T1 the actual speed reaches the target value and the changeover to the speed controller takes place. Done. As in this preferred embodiment, in this case the speed controller is a so-called P
It may be a DT1 controller, that is, a controller that also includes a delayed differential component in addition to the proportional component.

In both embodiments, similar behavior of the vehicle is achieved under all driving conditions. In this case, even on a steep slope, the predetermined target speed is always reliably achieved without substantially increasing the control cost. In this case, the configuration of the controller used is straightforward and easy to apply. The start condition of the controller configuration is a simple switch on / off condition.
Therefore, no expensive adaptation process is required to determine the starting value. The pre-control, the controller and the characteristic curve can be applied separately from each other, so that each component function is evaluated individually in a vehicle experiment and can always be applied. The actual acceleration is calculated by the controller 3
No expensive filtering is necessary as the threshold is only queried at the start of 6 (36 '). In addition, the disturbance effect on the driver, which acts as a disturbance to the device, especially just below a predetermined target speed (for example, due to an incorrect start value, an undesired starting value of the preliminary control), is completely eliminated.

In the preferred embodiment, the controller arrangement shown is implemented as a computing program in a microcomputer. An example of such a program is shown as a flow chart in FIG. In this case, the program part shown is started when the controller arrangement is activated at predetermined time intervals.

First, in a first step 300, the actual speed Vist, the predetermined target speed Vsoll, the driver set value SollF and the input travel stage Gist are read. In the following step 302, the actual acceleration Aist is determined as a function of the actual speed Vist, the speed difference ΔV is determined from the difference between the predetermined target speed Vsoll and the actual speed Vist, and the target acceleration Av is determined based on this speed difference ΔV. Asoll is determined. In addition, the predetermined target speed Vsoll and the input travel stage Gis
The first preliminary control value VW1 is calculated on the basis of t, and the second preliminary control VW2 is calculated on the basis of the target acceleration Asoll and the input travel stage Gist. Then, in inquiry step 304, the speed difference ΔV is the predetermined value Δ.
A check is made to see if it has fallen below V0. The value of ΔV0 is in the range very close to the predetermined target speed, which in the preferred embodiment is 2 km / h. If ΔV is smaller than ΔV0, the speed control is activated in step 306, and the speed control calculates the set value SollV. In the subsequent step 308, the setting target value So of the setting element is set.
ll is formed based on the smaller of the controller setpoint SollV and the driver setpoint SolllF, the program portion is terminated and repeated after a predetermined time. If the speed difference ΔV is greater than the predetermined speed difference ΔV0, then in step 310 it is checked whether a start condition for the controller 36 exists. If there is no start condition for the controller 36, step 312 forms the control setpoint SolllR from the sum of both preliminary control values VW1 and VW2, and in the following step 314 the setpoint setpoint Sol for the set element is set.
l is formed from the smaller of the setpoint values SolllR and SollF, the program part is terminated and repeated after a predetermined time. If a start condition is present according to step 310, then in step 316 the speed difference ΔV, the time T, the actual speed Vist, and optionally the control target speed Vsoll * at the break point of the characteristic curve in the first embodiment. As a function, or in the second embodiment, a predetermined filter function calculates the changed control setpoint value Vsoll *. In the following step 318, the speed difference ΔV * supplied to the controller 36 is formed from the difference between the control target speed Vsoll * and the actual speed Vist, and in the following step 320, the control target value SollR * is changed. Calculated based on ΔV *. This is done in the first embodiment by a proportional controller and in the second embodiment by a proportional-integral controller. In the following step 322, the control starting value SollR
The control setpoint SollR is calculated from * and the preliminary control values VW1 and VW2, which is followed by step 314.

It is preferred that the method according to the invention is used within a speed limiter, but otherwise the method according to the invention is used in a speed controller which maintains the speed provided by the driver. Also has similar advantages.

Furthermore, in a preferred embodiment, two controllers are not used, but a constant selectable one
Two controls may be used, which may be set or shut off depending on operating conditions.

In both embodiments, the control target value Vs
oll * is continuously changed as a function of the corresponding value.

[0023]

The method of the present invention allows the vehicle speed to reach a target speed without the use of costly initialization and enablement algorithms and without determining the vehicle acceleration.

The advantage is that in all operating conditions
It is particularly advantageous that it can be obtained even on steep slopes.

It is particularly advantageous to be able to use a conventional controller which is used within a speed limit in order to bring the speed closer to a predetermined target speed, where less precision is required.

It is particularly advantageous that the method according to the invention can be applied in a straightforward and simple manner. Furthermore, since the control start condition is a simple switch on / off condition, no adaptive operation is required. It is particularly advantageous that the pre-control of the controller, the controller itself and the characteristic curve of the control setpoint can be applied separately from each other.

No expensive calculation of the actual acceleration is necessary, since only the threshold value has to be queried to activate the controller.

The disturbing effect on the driver of shutting off and reclosing the speed limiter, in particular just below a predetermined target speed, is completely eliminated by the method according to the invention.

[Brief description of drawings]

FIG. 1 is an overall block circuit diagram of a first embodiment of the present invention.

FIG. 2 is a time diagram showing the operation of the first embodiment of the present invention, FIG. 2a is a time diagram of the set value SolllF by the driver and the set value SollR by the controller (+ preliminary control), and FIG. FIG. 2c is a time diagram of the target acceleration Asoll and the actual acceleration Aist, and FIG. 2c is a time diagram of the actual speed Vist and a predetermined target speed or control target speed Vsoll or Vsoll *.

FIG. 3 is an overall block circuit diagram of a second embodiment of the present invention.

FIG. 4 is a time diagram showing the operation of the first embodiment of the present invention, FIG. 4a is a time diagram of the setting value SolF by the driver or the setting value SolR by the controller (+ preliminary control), and FIG. Actual speed Vist, predetermined target speed Vs
ol and filtered control target speed Vso
It is a time diagram of 11 *.

FIG. 5 is a flowchart for executing the second embodiment as a computer program.

[Explanation of symbols]

10 operation elements 12, 16, 17, 20, 22, 26, 29, 30, 3
4,38,44,48,52,56,58,60,6
8, 70, 72, 78, 82, 86, 90, 94, 10
0, 104, 106, 110, 112, 114, 116
Line 14 Memory element 18, 32, 42, 46, 102 Coupling stage (comparative stage) 24 Measuring device (vehicle speed) 28 Calculation element 36 Controller (acceleration controller) 40, 74 Switch element 50 Release element 54, 62, 92 , 98 Characteristic curve group element 76 Selection element 80 Setting element (throttle valve) 84 Controller (speed controller) 96 Measuring device (accelerator pedal position) 108 Differentiation stage 200 Filter block (filter element) Aist Actual acceleration Asoll Target acceleration Gist input Driven stage Set target value of setting element Solll Set value of driver SollR Set value of controller and pre-control SollR * control target value SollV Set value of speed controller Vist Actual speed Vsoll target speed Vsoll * Control target speed VW1 No. Preliminary control value of 1 VW2 2 of the preliminary control value [Delta] V the velocity difference (Vsoll-Vist) ΔV * speed difference (Vsoll * -Vist) ΔV0 predetermined value of [Delta] V

Claims (10)

[Claims] 1. A time-varying control target value for the traveling speed is provided to at least one controller that sets a setting element that influences the speed, and the at least one controller controls the vehicle speed to this control target. In a method for controlling or limiting a vehicle speed in which the vehicle speed is adjusted toward a value, a gradient of a control target value supplied to the at least one controller is an actual value existing when the controller is activated. And a method for controlling or limiting a vehicle speed, wherein the method is changed based on a predetermined target speed. 2. A characteristic curve with respect to time is given to change the control target value, and a slope of the characteristic curve is
2. The difference between the predetermined target speed and the actual speed and a function of the predetermined target speed to be reached.
the method of. 3. The method according to claim 1, wherein the change of the control target value is performed by at least one filter including a delay component. 4. The method according to claim 1, wherein the controller is a controller having a proportional component. 5. The control setpoint is formed from setpoints of the controller itself, and at least from preset setpoints which are a function of a predetermined target speed, target acceleration and travel stage. The method according to claim 1, wherein 6. The controller is activated when the sum of the set values of the preliminary control is smaller than the set value for the set element given by the driver or when the actual acceleration of the vehicle is larger than the target acceleration. Claim 1
5 to any one of the methods. 7. The control target value of the control value when the set value by the controller and the preliminary control again reaches the set value by the driver after the set value by the driver has dropped below the set value by the controller. After the characteristic curve is newly started and the set value by the driver is increased, when the set value of the controller again reaches the set value of the driver, the characteristic curve of the controller is started from the interrupted value. 7. A method according to any one of claims 1, 2 or 4 to 6, characterized in that 8. The method of claim 3 wherein the time constant of the filter is a function of vehicle speed. 9. The method according to claim 3, wherein the controller is a controller having proportional and integral components. 10. At least one controller for setting a setting element affecting speed, said at least one controller being provided with a time-varying control target value for traveling speed, said at least one control In a vehicle speed control or limiting device for adjusting the vehicle speed in a direction to bring the vehicle speed closer to the control target value, the gradient of the control target value supplied to the at least one controller is the controller. A vehicle speed control or limiting device, which is changed based on an actual value existing when the vehicle is operated and a predetermined target speed.