JP2008157181A - Control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve responsiveness to a throttle opening command and especially responsiveness when the amplitude of a throttle opening command value is small, in opening control for an electronically-controlled throttle valve. <P>SOLUTION: In this standard model type control device calculating a manipulated variable I<SB>com</SB>so that an actual controlled variable θ is matched with a target controlled variable θ<SB>com</SB>with predetermined standard model response characteristics, the standard model response characteristics are set to be relatively sharpened according as the target controlled variable θ<SB>com</SB>becomes smaller. Thereby, since a current command value (manipulated variable) of an electric motor 11 for driving a throttle when the amplitude of the throttle opening command value (target controlled variable θ<SB>com</SB>) is small becomes large, responsiveness when the amplitude of the throttle opening command value is small is increased. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a model reference control device that calculates an operation amount so that an actual control amount matches a target control amount with a desired response characteristic (reference response characteristic).

  As control for making the actual control amount coincide with the target value, for example, the current value that flows to the throttle actuator such as an electric motor so that the opening degree of the electronically controlled throttle valve follows the throttle opening command value with the reference model response characteristic There is so-called positioning control for calculating (current command value). As positioning control, there is known one based on PID control based on the deviation between the throttle valve opening command value and the actual throttle valve opening, or on the classical control theory combining PI control and speed feedback control. .

  However, when driving and controlling actuators such as the above electric motors, various disturbances and nonlinear factors such as static friction, motor torque ripple, intake negative pressure change, throttle opening measurement noise, throttle opening measurement resolution, etc. Therefore, in the conventional positioning control as described above, it is difficult to achieve a high level of both throttle control resolution and responsiveness.

As a configuration for solving this problem, Patent Document 1 discloses a configuration including a disturbance compensation unit that performs compensation for disturbance. Specifically, it is composed of a feedback model matching compensation unit and a disturbance compensation unit, and the sum of the current command values from each compensation unit is the final current command value. The disturbance compensator estimates the disturbance (including modeling errors and characteristic fluctuations) applied to the controlled object based on the final current command value, actual throttle opening, and the nominal model (representative dynamic characteristic model) of the controlled object. By correcting the current command value so as to cancel out the disturbance, the dynamic characteristics of the controlled object are matched with the nominal model. The model matching compensation unit is configured to perform feedback compensation so that the dynamic characteristic matched with the above-described nominal model matches the desired response characteristic (normative response).
JP 09-158664 A

  However, in the configuration described in Patent Document 1, the characteristic parameters of the reference model defined by the second-order lag model, such as the cutoff frequency and the attenuation rate, are always constant, and the response time is independent of the operating state of the actuator. It is constant. In other words, when the magnitude of the opening command value for achieving the target opening (hereinafter referred to as the amplitude of the opening command value) is large, the current command value becomes large and the potential of the throttle actuator is fully used. Although the response characteristic is small, if the amplitude of the opening command value is small, the current command value will be small despite the fact that a larger current can flow, and the response characteristic that fully utilizes the potential of the throttle actuator. There is a problem that it is not. If this is replaced with vehicle performance, the opening / closing operation of the throttle valve can be made faster, but it is not performed.

  By the way, due to the characteristics of the internal combustion engine, the sensitivity of the engine output to the throttle opening is higher in the lower opening range of the throttle valve, and the frequency of use of the lower opening range of the throttle valve is higher in urban areas. That is, the response in the low opening range has a great influence on the acceleration performance of the vehicle.

  Therefore, an object of the present invention is to improve the response when the amplitude of the opening command value is small.

  The control device of the present invention is a model reference type control device that calculates an operation amount so that an actual control amount matches a target control amount with a predetermined reference model response characteristic. A control device that is set to be relatively sharp as the amount decreases.

  According to the present invention, the smaller the target control amount is, the smaller the input of the controlled object, that is, the manipulated variable, thereby improving the responsiveness of the controlled variable within the potential range of the controlled object. This is because the operation amount increases as the response characteristic of the reference model increases. Therefore, for example, when the present invention is applied to the throttle valve positioning operation, the motor drive current in the region where the target throttle opening is small can be increased, thereby improving the responsiveness of the throttle opening.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a first embodiment of the invention will be described with reference to the drawings.

  FIG. 1 is a functional block diagram showing the configuration of the first embodiment of the throttle valve positioning control device 1.

  10 is a throttle device, 2 is an angle sensor, 3 is a sensor signal processing circuit, 4 is a throttle valve positioning controller, and 5 is a current control amplifier.

  The throttle device 10 includes an electric motor 11, a speed reducer 12, a throttle valve 14, and a rotating shaft 15.

  The throttle valve 14 is a butterfly-type opening / closing valve provided rotatably around a rotary shaft 15 provided so as to cross the intake passage 13, and the angle sensor 2 is provided at one end of the rotary shaft 15. The end is connected to the speed reducer 12.

  For example, a DC motor is used as the electric motor 11, and the output of the electric motor 11 is decelerated by the speed reducer 12 to open and close the throttle valve 14 biased by a spring (not shown).

  The throttle device 10 configured as described above is driven to open and close in accordance with the operating state of the engine, thereby adjusting the intake air amount introduced into the engine by changing the flow passage cross-sectional area of the intake passage 13.

  The angle sensor 2 detects the actual opening of the throttle valve 14 and outputs the detected value to the sensor signal processing circuit 3. The angle sensor 2 is a potentiometer type that outputs an analog signal, but a high-precision optical encoder may be used.

  The sensor signal processing circuit 3 is composed of an amplifier and an A / D converter, amplifies the analog signal from the angle sensor 2 and converts it into a digital signal, and outputs it to the throttle valve positioning controller 4.

The throttle valve positioning controller 4 is a microcomputer having a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), a digital port, an A / D port, a D / A port, and various timer functions. And a high-speed communication circuit. Then, it is calculated from the power supply voltage V _B of the current control amplifier 5, the actual opening θ of the throttle valve 14 detected by the angle sensor 2, and the accelerator opening of the driver (depressing amount of the accelerator pedal) (target opening calculating means). is input opening command value of the throttle valve 14 theta _COM that is, the current actual throttle opening theta is opening detection value of the throttle valve 14 to the electric motor 11 so as to follow the opening command value theta _com The command value I _com is calculated.

The current control amplifier 5 controls the switching time of the power transistor so that the actual motor current I follows the motor current command value _Icom . The current control amplifier 5 may be a feedback type current control amplifier using a current detection sensor, or obtains an effective voltage from the current command value I _com and controls the switching time of the current control power transistor. A feedforward current control amplifier may be used.

  FIG. 2 is a control block diagram showing a functional configuration of the throttle valve positioning controller 4.

The throttle valve positioning controller 4 includes an F / F compensation unit B30, a disturbance compensation unit B40, a reference model setting unit B50, and an F / B compensation unit B60. Reference numeral 100 in the figure is a control target of the throttle valve positioning controller 4, specifically, a current control amplifier 5, a throttle device 10, an angle sensor 2, and a sensor signal processing circuit 3. Further, the throttle opening command value θ _com is the target control amount, the actual throttle opening θ is the control amount, and the current command value I _com is the operation amount (control target input).

F / F compensation unit B30 for the throttle opening command value theta _com, the current command value so that the actual throttle opening theta matches with desired response characteristics (nominal response) to (FF term) I _com _ _FF calculate.

The disturbance compensator B40 calculates a disturbance compensation value I _DIS for making the dynamic characteristic of the controlled object 100 constant by correcting and estimating the disturbance including the parameter fluctuation to cancel it.

The reference model setting unit B50 sets the response characteristics of the reference model and calculates the throttle opening reference response θ _ref according to the throttle opening command value θ _com .

F / B compensation unit B60, in order to reduce the throttle opening nominal response theta _ref and the deviation of the actual throttle opening theta produced as impact compensation delay of the disturbance compensation module B40, throttle opening nominal response theta _ref and the actual Feedback compensation is applied to the deviation from the throttle opening θ.

  Details of processing in each of the control units B30 to B60 shown in FIG. 2 will be described with reference to FIG. FIG. 3 is a flowchart showing the control performed by the throttle valve positioning controller 4. This control is executed at the start of engine operation, and is performed at a constant cycle, for example, a cycle of 10 milliseconds.

In step S10, the output signal from the angle sensor 2 and the power supply voltage of the current control amplifier 5 are converted into predetermined physical units using an A / D converter built in the microcomputer, and the actual opening θ of the throttle valve 14 and the power supply are converted. The voltage V _B is calculated.

In step S20, the response characteristics of the reference model are set. The reference model G _m (s) is a second-order linear model as shown in Equation (1).

This sets a response characteristic that the actual throttle opening θ should satisfy with respect to the target throttle opening θ _com , and ω _m is a cut-off frequency (hereinafter simply referred to as cut-off frequency) of the reference model, ζ _m represents the attenuation rate (the cutoff frequency ω _m and the attenuation rate ζ _m are characteristic parameters of the reference model).

Cut-off frequency omega _m are read from the map data set in advance the cut-off frequency omega _m with respect to the target throttle opening theta _com. FIG. 4 is an example of map data, where the vertical axis represents the cutoff frequency ω _m and the horizontal axis represents the throttle opening command value (target throttle opening θ _com ). As shown in the figure, the cut-off frequency ω _m is set to have a relatively fast characteristic as the target throttle opening θ _com is small, and to a relatively slow characteristic as the target throttle opening θ _com increases. . Note that, in the low opening range and the high opening range of the target throttle opening θ _com, the cutoff frequency ω _m has a substantially constant value due to the upper and lower limits.

In step S30, the current from the target throttle opening θ _{com is} obtained by a feedforward model matching compensator G _FF (s) obtained by the product of the inverse system of the controlled object model G _P (s) and the reference model G _m (s). The command value (FF term) I _{com — FF} is calculated. However, the control target model G _P (s) is a transfer function of the throttle opening θ with respect to the current command value I _com , and is represented by Expression (2).

The model matching compensator G _FF (s) is calculated by G _m (s) / G _P (s). Since the cutoff frequency ωm of the reference model G _m (s) is scheduled, the integrator 1 / s is developed in such a way that it appears explicitly, and each integrator is discretized by Euler integration or the like to obtain an actual arithmetic expression (Expression 3).

In step S40, a throttle opening reference response θ _ref is calculated. Since the cutoff frequency ωm of the reference model G _m (s) is scheduled in the same manner as in step S30, each integration is performed by expanding the reference model G _m (s) so that the integrator 1 / s appears explicitly. The instrument is discretized to obtain an actual arithmetic expression. The formula is the same as that in step S30, and will be omitted.

In step S50, the feedback compensation shown in Formula (4) is applied to the deviation between the throttle opening reference response θ _ref calculated in step S40 and the throttle opening θ, and the current command value (FB term) I _{com — FB} is calculated. , the current command value calculated in step S30 (FF term) is added to the I _com _ _FF calculates a current command value I _com1. The control constants K _P and K _D are set in consideration of gain characteristics and phase margin.

Here, _TDIV in the equation (4) is a time constant of the first-order approximate differential filter, and is determined using an evaluation index such as a gain characteristic or a phase margin so as to ensure appropriate robust stability. Equation (4) is actually calculated using a recurrence equation obtained by discretization by Tustin approximation or the like.

In step S60, the disturbance applied to the control target is estimated using the throttle opening θ, the current command value I _com at the previous calculation, and the control target model _GP, and the current command value is corrected. Here, the disturbance compensator will be described with reference to FIG. 5 which is a configuration diagram of the disturbance compensator.

First, G _P (z ⁻¹ ) obtained by discretizing the control target model is represented by Expression (5). Then, the zero point of G _P (z ⁻¹ ) is extracted and Q (z−1) is assumed as shown in Expression (6).

The control block B41 is a filter H (z ⁻¹ ) obtained by adding Q (z ⁻¹ ) having a zero point of GP (z ⁻¹ ) to a low-pass filter H0 (z ⁻¹ ) having a steady gain of 1. . The control block B41 outputs a current command value I _com2 and low-pass filtering the previous current command value I _com.

The control block B42 is a filter H (z ⁻¹ ) / G _P (z ⁻¹ ). Therefore, the zero point that converges to -1 is canceled out, and the control block B42 becomes a stable digital filter. This control block B42 reversely calculates the current command value I _com based on the discrete system transfer function G _P (z ⁻¹ ) to be controlled from the current command value I _com to the throttle opening θ and the throttle opening θ. Further, the current command value I _com3 is output after low-pass filter processing.

Subtractor B44 subtracts the current command value I _com2 from the current command value I _com3, the deviation amount of the current command value I _com by the control target of the disturbance and parameter variation from the current control amplifier 5 to the sensor signal processing circuit 3 I _DIS (hereinafter referred to as disturbance estimate) is obtained. Further, the subtractor B45 subtracts and corrects the estimated disturbance value I _DIS from the current command value I _com1 , and outputs a final current command value I _{com from} which influences due to disturbance and parameter fluctuations are eliminated.

The disturbance estimated value I _DIS becomes zero when there is no disturbance or parameter fluctuation in the controlled object. When there is a disturbance d or a parameter variation Δ in the control target, Equation (7) is obtained.

Further, in the frequency band where the gain characteristic of H (z ⁻¹ ) is 1, Expression (8) is obtained.

That is, the influence of the disturbance d and the parameter fluctuation Δ is completely canceled, and the dynamic characteristic of the controlled object is made constant to the nominal model G _P (z ⁻¹ ). Increasing the cut-off frequency of H (z ⁻¹ ) provides the same effect up to the high frequency range, but conversely results in high gain feedback and decreases the stability margin, so a trade-off design is required.

The control block B43 is a limiter corresponding to the upper and lower limits of the motor current. By limiting the input of the disturbance compensator when the motor current that is the actual control target input is saturated, the disturbance estimated value I _DIS has an error. Prevents accumulation and prevents deterioration of response performance.

In step S <b> 70, the current command value I _com calculated so far is output to the current control amplifier 5 using the D / A function of the throttle valve positioning controller 4.

  The effect when the above control is performed will be described with reference to FIGS.

FIGS. 6 and 7 are time charts for the throttle opening, the motor current, and the cut-off frequency ω _{m of the} reference model in order from the top, and show the case where the throttle opening command is issued at t = 0.1. FIG. It should be noted that the throttle opening command has four types of amplitudes of 80 degrees, 40 degrees, 20 degrees, and 10 degrees.

FIG. 6 is a diagram showing a case where the cut-off frequency ω _{m of the reference} model is always constant, as in the past, and FIG. 7 is a case where the cut-off frequency ω _m is set according to the map of FIG. FIG. In the chart of throttle opening, solid lines a1 to a4 that change stepwise at t = 0.1 are reference models, and solid lines b1 to b4 and c1 that gradually converge to solid lines a1 to a4. c4 represents the normative response model. The broken lines in the throttle opening degree chart of FIG. 7 represent b1 to b4 of FIG. The solid line b1.about.b4 in charts Chart in and cut-off frequency omega _m of the current value, (c1.about.c4) represents the current value and the cut-off frequency corresponding to the nominal response model b1.about.b4.

As shown in FIG. 6, when the cutoff frequency ω _m is always constant, the time (response time) until the throttle opening reaches approximately 90% of the target opening is related to the throttle opening command value. It is almost constant. The peak of the current value increases as the amplitude of the throttle opening increases. That is, when the amplitude of the throttle opening command is large, the current flowing through the electric motor 11 also increases, and the generated torque of the electric motor 11 approaches the maximum torque, but when the amplitude of the throttle opening command is small, The current value becomes small, and the potential of the electric motor 11 is left unused. That is, when the amplitude of the throttle opening command is small, there is room for improving the responsiveness by flowing more current.

On the other hand, when the cutoff frequency ω _m is set according to the throttle opening command value, as shown in the current value chart of FIG. 7, the current value when the amplitude of the throttle opening command is c2 to c4 is shown. The peak is larger than when b2 to b4. Note that c1 is a case where the amplitude is substantially the maximum value, and is close to the maximum current even if the cut-off frequency ω _m is constant, and therefore substantially coincides with b1.

As shown in the throttle opening chart of FIG. 7, the response time of the throttle opening becomes shorter as the amplitude of the throttle opening command becomes smaller than when the cutoff frequency ω _{m is} constant.

That is, in positioning the throttle valve 14, the motor drive current that is the operation amount is limited, and as the target throttle opening θ _com is larger, the biasing force of a spring (not shown) attached to the throttle valve 14 is larger. Since the required motor drive current increases, the cutoff frequency ω _m is set using the map data shown in FIG. The response of the throttle opening can be improved within the saturation range.

  A second embodiment will be described.

In the present embodiment, the system configuration and the control performed by the throttle valve positioning controller 4 are basically the same as those in the first embodiment, but the target throttle opening θ _com performed in the step corresponding to step S20 in FIG. The setting method of the cut-off frequency ω _m is different. Specifically, a deviation Δθ (throttle opening deviation) between the target throttle opening θ _com and the actual throttle opening θ is obtained, and the cutoff frequency ω _m is read from map data stored in advance according to this value.

An example of map data used in this embodiment is shown in FIG. FIG. 8 shows the cutoff frequency ω _{m on} the vertical axis and the throttle opening deviation on the horizontal axis. The smaller the throttle opening deviation, the faster the cutoff frequency ω _m becomes, and the throttle opening deviation becomes smaller. It is set to have a relatively slow characteristic as it increases. As in FIG. 4, in the minimum and maximum regions of the throttle opening deviation, the cut-off frequency ω _m is a substantially constant value due to upper and lower limit restrictions.

As described above, in positioning the throttle valve 14, there is a limit to the motor drive current that is the operation amount. Further, since there is inertia in the rotating part, the required motor driving current increases as the deviation between the target throttle opening θ _com and the actual throttle opening θ increases. Therefore, the cut-off frequency ω _m is set based on the throttle opening deviation as shown in FIG.

The effect when the cutoff frequency ω _m is set by the map data of FIG. 8 will be described with reference to FIG. FIG. 9 is a time chart showing the throttle opening, the motor current, and the cut-off frequency ω _{m of the} reference model, as in FIG. As shown in FIG. 9, the cut-off frequency ω _m increases with time, that is, as the actual throttle opening θ approaches the target throttle opening θ _com .

According to the above control, when the amplitude of the throttle opening command is small, the peak of the current value approaches the peak of the current value when the amplitude of the throttle opening command is large, as in the first embodiment. Responsiveness is improved. Furthermore, even when the amplitude of the throttle opening command is large, when the actual throttle opening θ approaches the target throttle opening θ _com , that is, when the throttle opening deviation becomes small, the response is smaller than when the cutoff frequency ω _m is constant. Improved (response time is shortened).

  A third embodiment will be described.

In the present embodiment, the system configuration and the control performed by the throttle valve positioning controller 4 are basically the same as those in the first embodiment, but the target throttle opening θ _com is performed in a step corresponding to step S20 in FIG. The setting method of the cut-off frequency ω _m is different. Specifically, the cut-off frequency ω _m is read from previously stored map data in accordance with the current command value I _com one sample period before. Note that a value obtained by measuring an actual current value may be used instead of the current command value _Icom .

An example of map data used in this embodiment is shown in FIG. In FIG. 10, the vertical axis is the cut-off frequency ω _m , the horizontal axis is the current command value I _com , and the characteristic is fast when the current command value is smaller than the current saturation limit value, and extremely slow when the limit value is exceeded. It is set as follows.

The effect when the cut-off frequency ω _m is set using the map data set as described above will be described with reference to FIG. FIG. 11 is a time chart similar to FIG. 7 and FIG.

As shown in FIG. 11, the cut-off frequency ω _m increases with time, that is, as the actual throttle opening θ approaches the target throttle opening θ _com . In particular, when the amplitude of the throttle opening command is large, the cutoff frequency ω _m rapidly increases immediately after the throttle opening command is issued.

Looking at the throttle opening chart, the response time is shorter from when the throttle opening command amplitude is small to when it is larger than when the cutoff frequency ω _{m is} constant. Note that e1 indicating that the amplitude of the throttle opening is large is less responsive than b1 indicating that the cutoff frequency ωm is constant immediately after the throttle opening command. This is because the peak of the current value is suppressed lower than in the case where the cutoff frequency ω _{m is} constant.

  As described above, as in the second embodiment, the response can be improved from the case where the amplitude of the throttle opening command is small to the case where the amplitude is large, and the maximum current can be reliably limited.

  The present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made within the scope of the technical idea described in the claims.

It is a functional block diagram of a system to which the first embodiment is applied. It is a control block diagram which shows the function structure of the system to which 1st Embodiment is applied. It is a flowchart which shows the control routine of 1st Embodiment. It is a figure showing the map data for the cutoff frequency setting of 1st Embodiment. It is a control block diagram which shows the function structure of a disturbance compensator. It is a time chart of the cutoff frequency of the prior art, throttle opening, and an electric current value. It is a time chart of the cut-off frequency, throttle opening, and current value of the first embodiment. It is a figure showing the map data for the cutoff frequency setting of 2nd Embodiment. It is a time chart of the cut-off frequency, throttle opening, and current value of the second embodiment. It is a figure showing the map data for the cutoff frequency setting of 3rd Embodiment. It is a time chart of the cut-off frequency, throttle opening, and current value of the third embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Throttle valve positioning control device 2 Angle sensor 3 Sensor signal processing circuit 4 Throttle valve positioning controller 5 Current control amplifier 10 Throttle device 11 Electric motor 12 Reducer 13 Intake passage 14 Throttle valve 15 Rotating shaft

Claims (4)

A model reference type control device that calculates an operation amount so that an actual control amount matches a target control amount with a predetermined reference model response characteristic,
A control device characterized in that the reference model response characteristic is set to be relatively sharp as the target control amount decreases. A control device for positioning a throttle valve of an internal combustion engine in which a control target is a throttle valve, and the control amount is an opening of the throttle valve,
The control device according to claim 1, wherein a characteristic parameter of the reference model is set based on a target opening of the throttle valve. A control device for positioning a throttle valve of an internal combustion engine in which a control target is a throttle valve, and the control amount is an opening of the throttle valve,
The control device according to claim 1, wherein a characteristic parameter of the reference model is set based on a deviation between a target opening of the throttle valve and an actual opening. The object of control is the throttle valve, and the control amount is the opening of the throttle valve,
A control device for positioning a throttle valve of an internal combustion engine with a drive current of a motor for driving the throttle valve as an operation amount,
The control device according to claim 1, wherein a characteristic parameter of the reference model is set based on the driving current.

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