JP4065342B2 - Method and apparatus for controlling vehicle speed - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention provides a vehicle running speed Control method And the apparatus.
[0002]
[Prior art]
A method of this kind or a device of this kind is known from German Offenlegungsschrift 3510174 (US Pat. No. 4,747,051). Here, a travel 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 when approaching a predetermined speed in a dynamic operation state. Yes. 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 control at the same time, so that in all cases the predetermined speed cannot be fully reached. Furthermore, in order to make a sufficient transition from one controller to another, the integral component of the controller is set when transitioning to a specific value. In this case, an expensive algorithm must be used for the operation and initialization of the destination controller, which likewise affects the reaching operation of the target value.
[0003]
From German Patent Publication No. 2842023, a running speed controller is known in which a control target value which changes over time is given in order to reach the actual speed. In this case, this control target value is formed as a curved curve having a predetermined gradient, 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. It is a function of a difference between a given target speed and a control target speed that changes over time, or a function of a difference between a control target value that changes over time and an actual value. However, this method does not achieve a sufficient target value in all cases unless an expensive algorithm is used.
[0004]
[Problems to be solved by the invention]
Therefore, the vehicle's running speed must be sufficient to reach a certain speed in all driving conditions. Control It is an object of the present invention to provide.
[0005]
[Means for Solving the Problems]
The vehicle speed of the present invention for adjusting the vehicle speed Control method And in the device, the at least one controller for setting the setting element which influences the speed is given a control objective value which varies with time with respect to the traveling speed. At least one controller adjusts the vehicle speed in a direction to bring the vehicle speed closer to the control target value. In this case, the slope of the control target value supplied to the at least one controller is changed based on the actual value and the predetermined target speed that are present when the controller is activated.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows an overall block circuit diagram of a first embodiment of the method according to the invention. Here, there is shown an operating element 10 for setting a predetermined target speed or speed limit that can be operated by a driver, and the operating element 10 is coupled to a memory element 14 via a line 12. A line 16 leads from the memory element 14 to a coupling stage 18 for forming a deviation between a predetermined target speed and an actual speed. The coupling stage 18 is fed with a line 20 from a line 22 which exits from a measuring device 24 for measuring the vehicle speed. The output line 26 of the comparison element 18 leads to a 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. The Further, a line 17 communicates from the line 16 to the calculation element 28. The other input line shows line 29, which emerges from line 48, described below, to activate and deactivate the computing element 28. The output line 30 of the calculation 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 a dynamic operating state (leading to a predetermined target speed). Therefore, this controller is also called an acceleration controller. The output line 38 of the controller 36 leads to the coupling stage 42 via the switch element 40 and the output line 44 of the coupling stage 42 leads to the other coupling stage 46. In this case, the switch element 40 is switched by the release element 50 via the line 48. The coupling stage 42 is supplied with the line 52 from the characteristic curve group element 54, and the characteristic curve group element 54 is supplied with the line 56 and line 58 from the line 16, and the actual transmission of the vehicle transmission device is supplied via the line 58. The travel stage (actual gear stage) is transmitted. Similarly, a line 60 is supplied to the coupling stage 46, and the line 60 leads from the characteristic curve group element 62 to the coupling stage 46. The characteristic curve group element 62 is supplied with a line 66 extending from a line 68 and a line 70 extending from a line 58, which will be described later. The output line 72 of the coupling stage 46 leads to a selection element 76 via a switch element 74, and the output line 78 of the selection element 76 leads to a setting element 80, preferably a throttle valve, for adjusting the vehicle speed. In addition to the line 72, the switch element 74 is supplied with a line 82 from the controller 84, and the controller 84 is supplied with a line 86 from the line 26. The controller 84 controls the speed in the steady operation state, and therefore the controller 84 is also referred to as a speed controller. Switch element 74 is operated via line 80 and line 88 also branches off line 26. Further, a 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 supplied with a line 94 from a measuring device 96 for measuring the position of the accelerator pedal operable by the driver. Further, a characteristic curve group element 98 is provided, and the line 100 extending from the line 26 is supplied to the characteristic curve group element 98. 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. A line 106 is supplied to the comparison stage 102 from the differentiation stage 108 for forming the actual acceleration Aist of the vehicle. A line 110 is supplied from the line 22 to the differential stage 108. In addition to line 104, release element 50 is further supplied with line 112 from line 90, line 114 from line 52, and line 116 from line 60.
[0007]
The embodiment shown in FIG. 1 shows an automobile speed limiter in which the controller 36 is actuated in the direction of acceleration control to reach a predetermined target speed in order to guide the speed to the speed limit. , Controller 84 is actuated in the direction of speed control. As a function of the difference ΔV between the predetermined target speed Vsoll and the actual speed Vist, switching takes place between both controllers (by means of the switch element 74). In the preferred embodiment, the controller 84 itself is activated when the speed difference falls below a predetermined speed difference that 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 is further performed as indicated by the characteristic curve group elements 54 and 62. The first preliminary control value VW1 is formed in the characteristic curve group element 54 as a function of the travel (gear) stage and the predetermined target speed Vsoll. The second preliminary control value VW2 is determined in the characteristic curve group element 62 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 a no-load vehicle. This means that, in the ideal case, only preliminary control is sufficient for vehicle acceleration and therefore the controller 36 need only 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 preliminary controls 54 and 62 or the speed controller 84 generate a target value for setting the setting element 80 which affects the speed. In this case, each target value is supplied to a selection element 76, which forms the minimum value of each control target value as well as the target value derived from the accelerator pedal operation via the line 90. The value is further supplied to the setting element 80. The driver's set target value is determined in the characteristic curve group element 92 as a function of the accelerator pedal's degree of operation and possibly as a function of other operating variables such as, for example, engine speed.
[0008]
In the preferred embodiment, a simple proportional controller is used as the controller 36. In this case, the amplification factor of the proportional controller is a function of the travel stage that has been applied.
[0009]
As a target set value, a speed target value that changes with time, a so-called speed characteristic curve (ramp) is supplied to the controller 36, and the gradient of the speed characteristic curve is a function of a predetermined target speed and a speed difference. Thereby, the controller superimposes the additional set value on the preliminary control (positive or negative). A time-varying control target speed is formed in the calculation element 28, and the gradient of the target value characteristic curve is determined based on the predetermined target speed and the speed difference.
[0010]
The characteristic curve obtained in the calculation element 28 is formed up to a range in which the speed difference is reduced so that it can be switched to the speed controller. In terms of control technology, this means that a variable I component is formed in addition to the proportional component of the controller 36. In this case, the gradient of the characteristic curve becomes flatter as it approaches the predetermined target speed. Therefore, since the preliminary control is intended to be performed on a flat road and on a no-load vehicle, the characteristic curve becomes longer on a steep slope.
[0011]
In a preferred embodiment, the characteristic curve of the control target value and the setting signal of the controller 36 are obtained only under specific conditions to be inspected by the release element 50. When the driver makes settings via preliminary control, i.e. when the driver wants to set a speed above a predetermined target speed, the release element 50 releases the controller 36 and the characteristic curve. For this reason, not only the driver setting value but also the preliminary control value is supplied to the release element 50. If the driver set value SollF 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 preliminary control value so that the setting element is as long as the target value SollR formed from the controller 36 and the preliminary control value is less than the driver setting value SollF. It is set based on this target value SollR. In this case, the characteristic curve of the control target value starts from the actual speed existing at the time of operation, and therefore the control deviation of the controller 36 is zero at the time of start. Therefore, no initialization routine is necessary.
[0012]
When the driver releases the accelerator pedal, that is, when the driver set value falls below the preliminary control, that is, the controller 36 and the preliminary control target value SolR again exceed the driver target value SolF and the setting element 80 is the driver target When set as a function of the value SollF, the formation of the characteristic curve is stopped. Next, when the target value of the driver again exceeds the target value of the controller, the formation of the characteristic curve is started again from the stopped value. In this case, the set value of the controller 36 is set to a value before being shut off. For example, when the driver sets a target value of 50% of (maximum throttle valve opening), the preliminary control is 35% (steep slope), and at this time, the controller 36 opens to 15%. At this time, the characteristic curve is interrupted. Next, if the driver further depresses the accelerator pedal to 70%, for example, the characteristic curve of the controller 36 starts from a value of 50% and increases to a maximum of 70%. If the driver does not step on the pedal to 70% and returns to 40%, the characteristic curve and controller 36 will start from this 40%. However, if the driver setpoint drops below pre-control, the next time the switch-on condition exists, the characteristic curve and controller 36 will start again from zero. The lines required to perform this function, which supply the actual speed to the calculation element 28, as well as the lines necessary to set the start value of the controller 36 are shown in FIG. Not.
[0013]
Another switch-on criterion for the controller 36 and characteristic curve is acceleration. When the actual acceleration of the vehicle 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 below the preliminary control (such as when the controller 36 is not activated because the preliminary control is greater than the driver's set value), such as when going down a slope, the traveling speed is predetermined. It is prevented that the speed is increased beyond the target speed. Thus, the controller 36 (and the target value characteristic curve) is started when the target acceleration is exceeded to prevent speed overswing.
[0014]
An example of the operation of the method according to the invention is shown in FIGS. 2a-2c. 2a shows a time diagram of the set value SollF by the driver and a 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. 2c shows a time diagram of the actual speed Vist and the predetermined target speed Vsoll to the control target speed Vsoll *. It is assumed that the travel speed limiter is activated, that is, the difference ΔV between the limit speed Vsoll and the actual speed Vist given by the driver is smaller than the limiter activation threshold. First, the vehicle is accelerated based on a target value SollF 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 for controller 36 are met. At time T0, the actual acceleration Aist exceeds the target acceleration Asoll. This means that the control target speed Vsoll * that changes in a characteristic curve shape is given to the controller 36 after the time T0. Next, the controller 36 corrects the preliminary control value, that is, SollR, based on the difference between the control target speed Vsoll * and the actual speed Vist. At the time T0 ′, the control setting value SollR calculated from the preliminary control and the control value is lower than the value SollF given by the driver, so that the setting element is set as a function of the control setting value SollR. As the controller 36 operates, the actual acceleration of the vehicle decreases to the time T1. At this point, the actual speed is in a range close to the predetermined target speed that activates the speed controller that maintains the predetermined target speed. At time T1, the controller 36 and the formation of the characteristic curve are stopped. The set value SollR is formed again by the preliminary control. However, since the set element is set as a function of the speed controller (or the set value of the driver), this set value SollR is adjusted after the time point T1. There is no. From FIG. 2, it is clear that the method of the present invention can achieve the actual speed sufficiently to reach the target speed without incurring a large expense.
[0015]
FIG. 3 shows a second embodiment of the method according to the invention. This is different from the embodiment shown in FIG. 1 in the following points. A description of the elements used in the same way in both embodiments is 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 temporally adjusted control target speed Vsoll * and the measured actual speed Vist. In this case, the filter element 200 is directly supplied on the one hand with the line 16 from the memory element 14 of the target value and on the other hand with the line 20 transmitting the actual speed Vist. All other elements correspond to the elements of the first embodiment in their function. 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 a first order filter, a so-called PT1 filter. In this case, the filter time constant is a function of the speed present when the controller 36 'is activated. In other advantageous embodiments, other filters have also been found suitable. It is important that the filter used contains at least one first order delay. The controller 36 is designed as a controller having proportional and integral components in order to maintain steady accuracy. The process of reaching the predetermined target speed is set using a filter time constant that is a function of speed in the preferred embodiment. Therefore, it is considered that the acceleration capability of the vehicle is reduced at high speeds. The switch-on conditions for the controller 36 ′ and the control target value setting correspond to the switch-on conditions of the embodiment shown in FIG. This means that the controller 36 ′ and the filter element 200 are activated when any switch-on condition exists in the release element 50. The predetermined target speed stored in the memory element 14 starts from the actual speed at that time, and uses a time constant as a function of the actual speed at that time, thereby controlling the control target speed Vsoll * as the basis of control. To be filtered.
[0016]
An example of the process of reaching the predetermined target speed is shown in FIG. Here, FIG. 4a shows a time diagram of the set value SollF by the driver or the set value SollR by the controller 36 '. 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 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' during this operation process. It is assumed that the set value of the controller 36 'falls below the driver set value at time T0, that is, the sum with the preliminary control value becomes smaller than the driver set value SollF. This means that the controller 36 'and the filter have been activated at time T0. Therefore, after the time T0, the filtered control target speed Vsoll * starts from the actual speed Vist at the time T0 and is led to the predetermined target speed Vsoll based on the filter time constant. The controller 36 'forms a correction signal for the preliminary control based on the difference between the control target speed Vsoll * and the actual speed Vist so that the actual speed reaches the target value at time T1 and Switching takes place. Similar to this preferred embodiment, in this case the speed controller may be a so-called PDT1 controller, i.e. a controller which also contains a delayed derivative component in addition to a proportional component.
[0017]
In both embodiments, similar behavior is achieved for the vehicle under all driving conditions. In this case, even on a steep slope, the predetermined target speed is always reliably achieved without substantially increasing the cost for control. In this case, the configuration of the controller used is easy to understand and can be easily applied. The start condition of the controller configuration is a simple switch on / off condition and therefore does not require an expensive adaptation process to determine the start value. Preliminary controls, controllers and characteristic curves can be applied separately from each other, so that each component function is evaluated individually in vehicle experiments and can be applied constantly. In fact, the acceleration calculation does not require expensive filtering since the threshold is only queried at the start of the controller 36 (36 '). Furthermore, disturbing influences on the driver acting as a disturbance to the device are completely eliminated, in particular immediately below the predetermined target speed (for example due to an incorrect start value and an undesired starting value of the preliminary control).
[0018]
In the preferred embodiment, the illustrated controller configuration is implemented as a microcomputer calculation program. An example of such a program is shown as a flowchart in FIG. In this case, the illustrated program portion is started when the controller configuration is activated at predetermined time intervals.
[0019]
First, in the 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 subsequent 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 is determined based on the speed difference ΔV. Asoll is determined. Further, the first preliminary control value VW1 is calculated based on the predetermined target speed Vsoll and the input travel stage Gist, and the second preliminary control VW2 is calculated based on the target acceleration Asoll and the input travel stage Gist. The Thereafter, in inquiry step 304, it is checked whether the speed difference ΔV is below a predetermined value ΔV0. The value of ΔV0 is in a range very close to the predetermined target speed, and 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 a set value SollV. In the subsequent step 308, the setting target setting value Soll is formed based on the smaller one of the controller setting value SollV and the driver setting value SollF, the program portion is terminated and a predetermined time has elapsed. Iterate afterwards. If the speed difference ΔV is greater than the predetermined speed difference ΔV0, it is checked in step 310 whether a start condition for the controller 36 exists. If the start condition for the controller 36 does not exist, the control set value SollR is formed from the sum of both preliminary control values VW1 and VW2 in step 312. Formed from the smaller of the SollF, the program part is terminated and repeated after a predetermined time. If a start condition exists at step 310, then at step 316, the speed difference ΔV, time T, actual speed Vist, and possibly the control target speed Vsoll * at the interruption point of the characteristic curve in the first embodiment. As a function, or in the second embodiment, the changed control target value Vsoll * is calculated by a predetermined filter function. In the subsequent step 318, a 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 step 320, the control target value SollR * is converted into the speed difference. Calculated based on ΔV *. This is done by a proportional controller in the first embodiment and by a proportional-integral controller in the second embodiment. In the following step 322, the control set value SollR is calculated from the control starting value SollR * and the preliminary control values VW1 and VW2, and then step 314 follows.
[0020]
Although it is preferred that the method according to the invention is used within the scope of a speed limiter, the method according to the invention is otherwise the same when used in a speed controller that maintains the speed given by the driver. Has many advantages.
[0021]
Furthermore, in an advantageous embodiment, instead of using two controllers, a single controller with a selectable constant is used, which can be set or shut off depending on the operating conditions. May be.
[0022]
In both embodiments, the control target value Vsoll * is continuously changed as a function of the corresponding value.
[0023]
【effect】
The method of the present invention allows the vehicle speed to reach the target speed without using expensive initialization algorithms, enabling algorithms, and without determining vehicle acceleration.
[0024]
It is particularly advantageous that this advantage can be obtained on steep slopes in all operating conditions.
[0025]
It is particularly advantageous to be able to use a normal controller which is used within a speed limit to bring the speed closer to a predetermined target speed, and which does not require much precision here.
[0026]
It is particularly advantageous that the method according to the invention can be applied easily and simply. Furthermore, since the control start condition is a simple switch on / off condition, no adaptive operation is required. It is particularly advantageous that the characteristic curves of the preliminary control of the controller, the controller itself and the control target value can be applied separately from one another.
[0027]
In order to operate the controller, only the threshold value needs to be queried, so expensive actual acceleration calculations are not necessary.
[0028]
Interference effects on the driver, such as shutting off and re-introducing the speed limiter, especially just below the predetermined target speed, are completely eliminated by the method according to the invention.
[Brief description of the drawings]
FIG. 1 is an overall block circuit diagram of a first embodiment of the present invention.
2 is a time diagram showing the operation of the first embodiment of the present invention, FIG. 2a is a time diagram of a set value SollF by a driver and a set value SollR by a 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 to 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 a set value SollF by a driver or a set value SollR by a controller (+ preliminary control), and FIG. It is a time diagram of actual speed Vist, predetermined target speed Vsoll, and filtered control target speed Vsoll *.
FIG. 5 is a flowchart for executing the second embodiment as a computer program;
[Explanation of symbols]
10 Operating elements
12, 16, 17, 20, 22, 26, 29, 30, 34, 38, 44, 48, 52, 56, 58, 60, 68, 70, 72, 78, 82, 86, 90, 94, 100, 104, 106, 110, 112, 114, 116 lines
14 Memory elements
18, 32, 42, 46, 102 Combined stage (comparison stage)
24 Measuring device (vehicle speed)
28 Calculation elements
36 Controller (Acceleration controller)
40,74 switch elements
50 release elements
54, 62, 92, 98 Characteristic curve group elements
76 Selected elements
80 Setting elements (throttle valves)
84 Controller (Speed controller)
96 Measuring device (accelerator pedal position)
108 Differential stage
200 Filter block (filter element)
Aist Actual acceleration
Asoll target acceleration
Gist Driven stage
Set target value of the Soll setting element
Set value of the SollF driver
Set values for the SollR controller and preliminary control
SollR * control target value
Set value of SollV speed controller
Vist actual speed
Vsoll target speed
Vsoll * control target speed
VW1 First preliminary control value
VW2 Second preliminary control value
ΔV Speed difference (Vsoll-Vist)
ΔV * Speed difference (Vsoll * -Vist)
ΔV0 ΔV predetermined value

Claims (9)

At least one controller that sets a setting factor that affects the speed is given a control target speed that varies with time relative to the running speed,
Wherein the at least one controller, the control personage method of vehicle speed for adjusting the vehicle speed in a direction to approach the vehicle speed to the control target speed,
In order to change the control target speed , a characteristic curve with respect to time is given,
Gradient of the characteristic curve, and characterized in that the difference, Oyo function of target velocity beauty plants constant between the actual speed which is present when operated with the controller to a predetermined target speed to be reached control personage method of vehicle speed to be. The method of claim 1, wherein the change in the control target speed is performed by at least one filter including a delay component. 3. The method according to claim 1 , wherein the controller is a controller having a proportional component. 2. The control target speed is formed from a set value of the controller itself and from a set value of a preliminary control which is a function of at least a predetermined target speed, a target acceleration and a travel stage. Any one of methods 3 . Wherein when the sum of the preliminary control set value is smaller than the set value for the setting elements provided by the driver, or when the actual acceleration of the vehicle is greater than the target acceleration, claim, characterized in that the controller is activated 4 the method of. After the driver settings drops below the set value of the controller, when the setting value by the controller and the preliminary control reaches the set value again by the driver, the characteristic curve of the control target speed new Started
After the set value by the driver is increased, the claims set value of the controller is when it reaches again the driver settings, characterized in that the characteristic curve of the controller is started from the interrupted values Method 4 or 5 . The method of claim 2 , wherein the time constant of the filter is a function of vehicle speed. The method of any of claims 2 or 7, wherein the controller is a controller with proportional and integral components. Comprising at least one controller for setting a setting element which influences the speed;
The at least one controller is provided with a control target speed that varies with time with respect to the traveling speed;
Wherein the at least one controller, the control equipment of the vehicle speed for adjusting the vehicle speed in a direction to approach the vehicle speed to the control target speed,
In order to change the control target speed , a characteristic curve with respect to time is given,
Gradient of the characteristic curve, and characterized in that the difference, Oyo function of target velocity beauty plants constant between the actual speed which is present when operated with the controller to a predetermined target speed to be reached A vehicle speed control device .

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