JP4309530B2 - Method and apparatus for controlling frictional adhesion setting element - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and apparatus for controlling a frictional adhesion setting element.
[0002]
[Prior art]
In many technical applications, operating variables are set via frictional adhesion setting elements. An example from the range of automotive control is the setting of frictional adhesion setting elements, for example, the setting of electrically operated throttles within the range of output control, rotational speed control or drive slip control. A corresponding control device is described in EP 656778 (US Pat. No. 5,144,915). The difficulty in carrying out the control given by the frictional attachment of the setting element, in particular the static friction of the setting element, is overcome in this case by adjusting at least one constant of the control device to limit the rate of change of the controlled variable. The However, such a control device is not necessarily suitable for all applications.
[0003]
The frictional adhesion setting element that is biased in the predetermined direction of movement by the at least one restoring device is operated by a digital controller (for example a digital position controller) having an integral part. A torque against the bias that serves to move the setting element against the bias and to hold the setting element in place is provided via an integral portion of the controller. In addition to this, for example, when a high static friction value occurs as a function of temperature, the integral part may approach its upper or lower limit before the setting element starts moving from its static friction position. When the control circuit reaches equilibrium and the setting element is again in the neutral position with static friction, the high value integral part continues to exist. As a result, the average current flowing through the setting element exceeds a predetermined continuous current. Similarly, the operation signal value of the setting element for setting the current exceeds the predetermined limit value. This results in a set element damage or error monitoring response. However, this characteristic is undesirable because it limits the availability of the setting elements or the overall control.
[0004]
[Problems to be solved by the invention]
Improve the usability of control of the frictional adhesion setting element, and the current and / or operation signal value flowing through the setting element exceed a predetermined limit value in an operating state where the average current or the operation signal value flowing through the setting element is high It is an object of the present invention to effectively prevent this.
[0005]
[Means for Solving the Problems]
The above problem is that the setting element is operated by at least one operation signal τ, and the operation signal τ is formed as a function of the target value SOLL and the actual value IST by a control device including at least one integral part. In the control method, in an operating state where a high average current flowing through the setting element or a large operation signal value is generated, the integral part or the operation signal value τ is a predetermined value IMIN that forms a normal current level in the setting element, This is achieved by the method for controlling the frictional adhesion setting element of the present invention, which is set to IMAX.
[0006]
The task also includes control means for forming an operation signal τ for operating the setting element as a function of the target value SOLL and the actual value IST, the control means having a frictional adhesion setting element having at least one integral part. In the control device, setting means is provided, and when the average current flowing through the setting element or an operation state with a high operation signal value exists, the setting means sets the integral part or the operation signal value τ to the predetermined values IMIN and IMAX. This is achieved by the control device for the frictional adhesion setting element of the present invention.
[0007]
The utilization of the control of the frictional adhesion setting element is clearly improved, and the integral part is set to a predetermined value when there is an operating condition with a high average current or operating signal value (eg when high static friction occurs). This effectively prevents the operation signal value or the average current flowing through the setting element from reaching the limit value. This value is chosen so that the control function of the setting element is not adversely affected.
[0008]
When the integral part exceeds the predetermined threshold for a predetermined time by comparing the integral part with a predetermined threshold value in the almost steady target value setting for the control circuit, a high static friction state is set to set the integral part. It is advantageous. In this way, a high static friction state is detected simply and reliably.
[0009]
It is particularly advantageous that the value to which the integral part is set is the threshold value used to detect high static friction conditions. This value is selected so that the position of the setting element does not change during the setting process, and the current level or the operation signal value is returned to the normal range. In determining the threshold, we start by considering the worst case for the set factor, but not the special static friction part. The setting element is held at the current position against the restoring force by the threshold value.
[0010]
By this means, it is particularly advantageous that cost-effective static friction considerations and compensations are made without requiring expensive structural changes in the setting elements. Thus, it is also possible to use setting elements which have a high static friction component which can vary and are therefore cost effective.
[0011]
It is particularly advantageous to use the method described above in combination with a digital position controller for a throttle valve of an automotive internal combustion engine operated by an electric setting element having a high static friction component at least under predetermined operating conditions.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings.
FIG. 1 is an overall circuit diagram of a control circuit having a frictional adhesion setting element. In a preferred embodiment, a control device 12 formed in the microcomputer 10 is provided. The control device 12 is supplied with a value representing the control deviation Δ from the comparison stage 14. This control deviation Δ is formed by comparing the target value SOLL and the actual value IST in the comparison stage 14. In this case, the actual values are supplied to the microcomputer 10 from the measuring device 16, while the target values are formed as a function of operating variables in the target value forming stage 18, and these operating variables are supplied from the corresponding measuring devices 20 to 24. . The control device 12 itself forms an output signal τ as a function of the control deviation Δ according to a predetermined control algorithm including at least one integral part, the output signal τ being set elements in a direction that brings the actual value closer to the target value. Is configured to be manipulated. The operation signal value τ that is an output signal is supplied to the electrically operated frictional adhesion setting element 28 via the final stage 26, and this setting element 28 is operated by the operation signal value.
[0013]
In a preferred embodiment, the frictional adhesion setting element 28 is an electrically operated throttle valve for an internal combustion engine. In this case, the setting element is biased in the direction of movement by at least one restoring force, for example a return spring. In a preferred embodiment, two restoring forces are provided in opposite directions and the two restoring forces hold the setting element in place when not operated. This setting element is set within the digital position control circuit, in which case a target value for the position of the setting element is given, which is compared with the actual value measured at the setting element with respect to the position of the setting element. In this case, the target value is formed by an operating variable of the internal combustion engine, for example, the position of an accelerator pedal that can be operated by the driver, an idle rotation speed control device, or the like. In this case, the digital position controller comprises at least one integral part, preferably a proportional part, an integral part and a derivative part. In the preferred embodiment, an operating signal τ having a variable duty factor is provided as an output signal, which can vary between a negative maximum value and a positive maximum value. This duty factor is formed based on the control strategy and the supplied control deviation by the digital position controller and is output to the final stage 26, which in the preferred embodiment is an H-bridge. Depending on the duty factor, the average current flowing through the setting element 28 is set and this average current operates the setting element or holds the setting element in place.
[0014]
In such an embodiment, a monitoring means not shown in FIG. 1 is provided, by which the operating signal value and / or the average current flowing through the setting element is compared with a predetermined limit value. When a predetermined limit value is exceeded, an error is inferred and the device is switched to emergency operation to protect the setting element from damage. However, this situation may also occur when a high static friction component appears in the setting element 28 as described at the beginning. If the setting element does not move the difference between the target value and the actual value due to static friction, the integral part of the control device will have a very large value. As a result, the average current flowing through the setting element 28 exceeds the maximum value given as a continuous current. Similarly, the duty factor value may take a value out of a predetermined value range. At this time, if the static friction is released and the target value and the actual value are matched, the integral portion and therefore the duty factor remain high. The reason is that the setting element is fixed in a new position by high static friction.
[0015]
Therefore, the present invention is designed to compare the value of the integral part with a threshold value. If the integral part is below the threshold value and the target value setting is almost steady, i.e., if the target value does not change within the predetermined limit range, the integral part will be the threshold value or Reset to the value derived from the threshold. It is thus avoided that a very large duty factor and / or a very high continuous current is provided in the setting device due to static friction after the end of the control process. In this case, the threshold value is selected so that the position of the setting element does not change and the current level returns to a normal value. In determining the threshold, the worst case of the setting factor is taken into account, in which case no special static friction part is taken into account. The continuity of target value setting is determined by a specific threshold value. After the integral part has been set to a predetermined value, the control device continues to execute so that the integral part can be reconfigured. Next, a new reset is performed if necessary. In some cases, this may be done in an iterative process, with this typical cycle time corresponding to the time given between exceeding the threshold and the set of integral parts.
[0016]
In this way a high continuous current in the setting element due to static friction is avoided and the advantages described at the outset are achieved.
In a preferred embodiment, the above method is formed as a program of the microcomputer 10. An example of such a program is illustrated by the flowchart of FIG. The program described therein is executed at predetermined time intervals of several milliseconds.
[0017]
After starting the program, in step 100, the target value and actual value (SOLL, IST) are read. In a subsequent step 102, the values of the integral part I, the proportional part P and / or the derivative part D are calculated on the basis of the target value and the actual value, in particular their deviation, corresponding to the control device used. For the integration part, the deviation between the target value and the actual value is integrated. In the subsequent step 104, the integral value I is compared with a predetermined threshold value IMIN. Further, the magnitude of the temporal change GRADSOLL (gradient) of the target value is compared with a predetermined threshold value GRAD0. When the integrated value and the temporal change of the target value are below the predetermined limit value, a static friction state is estimated. The same applies to the maximum integral value, and when the integral value exceeds the maximum value and the magnitude of the target value change is below the limit value, a static friction state is estimated. If the condition from step 104 is not met, step 116 decrements the counter T by the value Δ and limits it to the value 0, and then step 106 sets the output value τ to that of the control parts I, P and D. It is formed as a sum and output to the final stage (further setting element) by step 108.
[0018]
These step parts are the monitoring of the average current flowing through the setting element and / or the value of the duty factor τ, which is not shown in FIG. If the average continuous current and / or duty factor exceeds a predetermined limit value for a predetermined time, an error condition is inferred from this and this error condition interrupts the setting element.
[0019]
In order to avoid this error condition when this value exceeds a tolerance due to a static friction condition, if step 104 is affirmative, when a static friction condition is inferred, it is It is designed to compare the progressing counter T with the maximum value TMAX. If the counter state is not greater than the maximum value, the counter state is incremented at step 112 (eg, increased by a predetermined value Δ). Thereafter, the operation of the setting element in step 106 continues. When the counter state reaches the maximum value, in step 114 the integral part I is set to the threshold value IMIN (or IMAX) and the counter T is reset to the value 0. Thereafter, the setting elements are operated in steps 106 and 108.
[0020]
If the integral part falls below or exceeds the threshold value and the target value slope is almost steady, a static friction condition is inferred, and the static friction condition is Set to the corresponding threshold. Therefore, the problems related to error detection described at the beginning are effectively avoided.
[0021]
While and after setting the integral part to a predetermined value, the controller continues to execute again (steps 102, 106 and 108 are carried out in succession), so that a new integral part can be formed. it can. Next, a new reset is performed if necessary. In some cases, this may be done in an iterative process, with a typical cycle time being TMAX.
[0022]
FIG. 3 shows a time diagram of the passage of the integral part I, the target value SOLL and the actual value IST. First, it is assumed that the apparatus is in an equilibrium state and the integral part has a predetermined value. It is assumed that the target value SOLL is changed at the time T ₀ . Start with the device in a static friction condition. The integral portion I is lowered by the deviation existing between the target value SOLL and the actual value IST. Integral component I is to have exceeded the threshold IMIN at time T _1. Since the target value SOLL at this time T ₁ is substantially constant, the time T ₁ after the counter starts. At time T ₂ , an equilibrium state between the target value SOLL and the actual value IST is formed again, so that the integral part I is held at the value achieved at this time. It reaches the maximum value TMAX of the counter at time T _3, thereby integrating part I at this time T ₃ is reset to the value IMIN.
[0023]
The integral part corresponds at least approximately to the duty factor τ in steady state operation, and this duty factor τ is output for the operation of the setting element. To this extent, the corresponding means are alternatively performed with respect to the duty factor and not with respect to the integral part, in which case the corresponding absolute value is used to compensate for the high integral part beyond the tolerance. Is superimposed on.
[Brief description of the drawings]
FIG. 1 is an overall circuit diagram of a control circuit having a frictional adhesion setting element.
FIG. 2 is an example of a flow diagram illustrating a preferred embodiment.
FIG. 3 is an exemplary signal diagram according to a preferred embodiment.
[Explanation of symbols]
10 microcomputer 12 control device 14 comparison stage 16 measuring device (actual value)
18 Target value formation stage 20, 24 Measuring device (operating variable)
26 Final stage 28 Setting elements

Claims (3)

The setting element (28) is operated by at least one operating signal (τ), and the operating signal (τ) is controlled by the control device (12) including at least one integral part (I), and the target value (SOLL) and the actual value (SOLL) In a method for controlling a frictional adhesion setting element formed as a function of IST),
In an operating state where a high average current flowing through the setting element (28) or a large operation signal value is generated , that is, in an almost steady target value, the integral part or the operation signal value exceeds a predetermined threshold value for a predetermined time. in operating conditions which exist when the integral component (I) to the operation signal value (tau) is reset to a value derived from the predetermined threshold value (IMIN, IMAX) or the threshold value,
The threshold value is selected so that the position of the setting element does not change and the current level returns to a normal value .  The method according to claim 1, wherein the operating state is a state having a high static friction in the setting element. Control means (12) for forming an operation signal (τ) for operating the setting element (28) as a function of the target value (SOLL) and the actual value (IST), the control means (12) being at least one In a control device for a frictional adhesion setting element (28) having an integral part (I),
Setting means (114) is provided;
When there is an operating state in which the average current flowing through the setting element (28) or the operation signal value is high, that is, the integral part or the operation signal value exceeds a predetermined threshold value for a predetermined time at a substantially steady target value. When there is an operating condition that exists when the setting means resets the integral part (I) or the operation signal value (τ) to a predetermined value,
The predetermined value is the predetermined threshold or a value derived from the threshold;
The control apparatus for a frictional adhesion setting element, wherein the threshold value is selected so that the position of the setting element does not change and the current level returns to a normal value .

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