JP2013200779A - Feedforward control method and feedforward control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To appropriately generate an FF (feedforward) operation amount based on a target value with low man-hours, without the need of modeling a control object and without depending on the degree of change of the target value, in a control system for controlling the control object by feedforward control.SOLUTION: At every prescribed arithmetic timing, a target value smoothing processing unit 61 acquires a target value r(i) at the arithmetic timing, performs smoothing processing for the acquired target value r(i), and thus calculates a smoothed target value rfilt(i) for which the target value r(i) is smoothed. The smoothed target value rfilt(i) is subjected to a differential operation by a target value differential operation unit 71. Then, an FF operation amount calculation processing unit 72 appropriately adds the differential operation value and the smoothed target value rfilt(i) to calculate an FF operation amount u(i).

Description

  The present invention relates to a feedforward control method and a feedforward control device that perform feedforward control on a controlled object.

  Conventionally, as a control system, a so-called feedforward control system is known in which an operation amount is calculated from a target value by a predetermined calculation method without using a control output, and a control target is controlled by the operation amount. A two-degree-of-freedom control system that is a combination of a feedforward control system and a feedback control system is also known.

As a specific example of the feedforward control system, Patent Literature 1 describes a feedforward manipulated variable (hereinafter referred to as “FF manipulated variable”) from a target value r using an arithmetic expression set in advance based on the transfer function P to be controlled. A technique for calculating u _ff is described.

JP 2008-287581 A

  However, the feedforward control system described in Patent Document 1 is premised on model-based design based on a transfer function to be controlled. For this reason, if the controlled object cannot be modeled, it cannot be designed, and control design takes time.

On the other hand, as a method of calculating the FF manipulated variable u _ff with as little effort as possible (that is, without modeling), only the change in the target value r is captured and the change in the target value is differentiated. A way to do this is conceivable. However, the method of calculating the FF manipulated variable u _ff by differentiating the target value in this way has a problem that the FF manipulated variable u _ff becomes excessive when the change in the target value becomes large and cannot be used. In particular, the above problem becomes significant in a control system in which the target value r changes stepwise for each control cycle.

  The present invention has been made in view of the above problems, and in a control system that controls a control target by feedforward control, the control target is not required to be modeled and based on the target value regardless of the degree of change in the target value. An object of the present invention is to enable generation of FF manipulated variables appropriately and with low man-hours.

  The invention according to claim 1, which has been made in order to solve the above-described problem, is a feedforward control method for performing feedforward control on a control target, and obtains a target value at the calculation timing for each predetermined calculation timing. Then, by performing an annealing process on the acquired target value, the target value that has been smoothed is calculated, and the target value derivative is obtained by differentiating the calculated target value. A value is calculated, and a feedforward manipulated variable is calculated by a predetermined arithmetic expression using the calculated smoothing target value and target value differential value. Then, the control target is controlled using the calculated feedforward operation amount.

  In the present invention, the acquired target value is not used as it is, but the smoothed target value after the annealing process is used. That is, the smoothed target value subjected to the annealing process is set as a substantial target value at the calculation timing (a target value used for calculating the feedforward manipulated variable; hereinafter, also referred to as “actual target value”). Further, regarding the differentiation of the target value, the acquired target value is not differentiated, but the smoothed target value after the annealing process is differentiated.

  The annealing process is to limit the change of the target value, that is, the amount of change from the actual target value at the previous calculation timing to the actual target value at the current calculation timing is the change in the actual target value. In this process, the amount of change is limited so as to be smaller than the amount. In other words, it can be said that this is a process of smoothing the change of the target value acquired at each calculation timing and setting the smoothed target value as the actual target value (the smoothed target value).

  According to such a feedforward control method, differentiation is performed after the target value is smoothed, and the feedforward manipulated variable is calculated using the smoothed target value and the target value differential value. For this reason, even if the change of the target value is large (stepwise change), it is possible to prevent the target value differential value from becoming excessively large, without requiring modeling of the control target and depending on the degree of change of the target value. Therefore, the generation of the feedforward manipulated variable based on the target value can be realized appropriately and with a low man-hour.

  The invention according to claim 2 is a feedforward control device that performs feedforward control of a controlled object, acquires a target value at the calculation timing for each predetermined calculation timing, and performs the operation with respect to the acquired target value. By performing the annealing process, the target value is obtained by differentiating the annealing target value calculated by the annealing processing means and the annealing processing means for calculating the annealing target value. A manipulated variable for calculating the feedforward manipulated variable by a predetermined arithmetic expression using a differentiating means for calculating the differential value, the smoothing target value calculated by the smoothing processing means and the target value differential value calculated by the differentiating means. Calculating means. Then, the control target is controlled using the feedforward operation amount calculated by the operation amount calculation means.

  According to the feedforward control device configured in this way, the above-described feedforward control method of the present invention is realized, and the feedforward manipulated variable is calculated by the feedforward control method. It is done.

  As the predetermined calculation method used when the operation amount calculation means calculates the feedforward operation amount, for example, the calculation method described in claim 3 can be used. That is, the operation amount calculation means calculates the feedforward operation amount by adding the smoothed target value and the target value differential value after multiplying each by a predetermined coefficient.

  By calculating the feedforward manipulated variable by such a computation method, it is possible to easily generate an appropriate feedforward manipulated variable considering the target value and its change state.

  Invention of Claim 4 is the feedforward control apparatus of Claim 2 or Claim 3, Comprising: An annealing process means performs an annealing target with respect to the acquired target value by performing the smoothing target several times. Calculate the value.

  According to the feedforward control device configured as described above, since the smoothed target value is calculated by multiplying the target value a plurality of times, a larger smoothing effect can be obtained. Further, by appropriately setting the number of the annealing processes, a desired level of the annealing effect can be obtained, and the degree of freedom of the feedforward control is expanded.

  Although a specific method for performing the annealing process a plurality of times can be considered as appropriate, it can be performed, for example, as described in claim 5. That is, the invention according to claim 5 is the feedforward control device according to claim 4, wherein the smoothing processing means performs jth (j is 2 or more) from the first smoothing process at every calculation timing. (Natural number) It is configured to perform j annealing processes until the annealing process, and sequentially calculate the nth annealing value (n = 1 to j) for each annealing process. Specifically, in the first (first) first smoothing process, the target value acquired at the current calculation timing and the first smoothed value calculated in the first smoothing process at the previous calculation timing are obtained. The first smoothed value at the current calculation timing is calculated by weighted addition. In the second and subsequent n-th smoothing processes, the n-1th smoothing value calculated in the (n-1) th smoothing process, which is the (n-1) th smoothing process, and the previous calculation timing, respectively. The nth smoothing value at the current calculation timing is calculated by weighting and adding the nth smoothing value calculated in the n smoothing process. Then, the jth annealing value calculated in the last (jth) jth annealing process is calculated as the annealing target value.

  According to the feedforward control device configured as described above, it is possible to more surely obtain a desired level of smoothing effect by appropriately setting the number j of smoothing processes and the weighting in each smoothing process. And the degree of freedom of feedforward control is further expanded.

  The invention according to claim 6 is the feedforward control device according to any one of claims 2 to 5, wherein the differentiating means converts the smoothed target value into m-th order differentiation (m is 2 or more). Natural number), and the differential value of each floor is calculated as the target differential value.

  According to the feedforward control device configured as described above, since the differential value of each floor is reflected in the feedforward manipulated variable, it is possible to calculate a more appropriate feedforward manipulated variable that more reflects the change state of the target value. it can. In addition, the degree of freedom of feedforward control can be further expanded by appropriately setting the differential rank m.

It is explanatory drawing showing the whole structure of the vehicle control system of embodiment. It is a functional block diagram showing the structure of the air fuel ratio control system of embodiment. It is a flowchart showing the injector drive control process in the air fuel ratio control system of the embodiment. It is a flowchart showing the detail of the FB operation amount calculation process of S150 in the injector drive control process of FIG. It is a graph showing the change of the control amount and the operation amount when the target value changes stepwise, (a) is the control amount of the embodiment (combination of the FF control system and the FB control system to which the present invention is applied). The change and the change of the control amount of the conventional method (only the FB control system) are represented, and (b) represents the change of the operation amount of the embodiment and the change of the operation amount of the conventional method. It is a graph showing FF manipulated variable and FB manipulated variable in case a target value changes in steps in an embodiment, (a) expresses FF manipulated variable, and (b) expresses FB manipulated variable. It is a graph for demonstrating the effect of FB control, (a) represents that the disturbance generate | occur | produced at the time of 1 second, (b) is the case where FB control exists with respect to the change of the control amount with respect to the disturbance, and when it is not (C) represents each of the cases where the FB control is present and not performed with respect to the manipulated variable for the disturbance.

Preferred embodiments of the present invention will be described below with reference to the drawings.
A vehicle control system 1 according to the present embodiment shown in FIG. 1 controls an engine 10. In the vehicle control system 1, the control of the engine 10 that is an internal combustion engine is realized by an electronic control unit (ECU) 50 included in the system 1 executing various processes. Below, the whole structure of the vehicle control system 1 is demonstrated first, and the content of the process performed by ECU50 is demonstrated concretely after that.

(1) Overall Configuration of Vehicle Control System 1 As shown in FIG. 1, in the vehicle control system 1 of the present embodiment, an air cleaner 15 is provided at the most upstream portion of the intake pipe 13 of the engine 10. An air flow meter 17 for detecting the intake air amount is provided on the downstream side. A throttle valve 20 that is adjusted by a motor 19 and a throttle opening sensor 21 that detects the throttle opening are provided on the downstream side of the air flow meter 17.

  A surge tank 13a is provided on the downstream side of the throttle valve 20, and an intake pipe pressure sensor 23 for detecting the intake pipe pressure is provided in the surge tank 13a. The surge tank 13a is provided with an intake manifold 25 for introducing air into each cylinder of the engine 10, and an injector 27 for injecting fuel is provided near the intake port of the intake manifold 25 of each cylinder.

  In addition, the cylinder head of the engine 10 is provided with a spark plug 29 for each cylinder, and the air-fuel mixture in the cylinder is ignited by spark discharge of the spark plug 29. In addition, each of the intake valve 31 and the exhaust valve 32 included in the engine 10 is configured to be driven by the variable valve timing adjustment mechanisms 33 and 34. In the vehicle control system 1 according to the present embodiment, the intake valve 31 and the exhaust valve 32 correspond to the engine operating state. Thus, the intake / exhaust valve timing (VVT angle) is adjusted.

  Further, the exhaust pipe 35 of the engine 10 is provided with a catalyst 37 such as a three-way catalyst for purifying the exhaust gas, and an air-fuel ratio sensor 39 for detecting the air-fuel ratio λ of the exhaust gas is provided on the upstream side of the catalyst 37. It has been. In addition, the cylinder block of the engine 10 is provided with a water temperature sensor 41 for detecting the cooling water temperature and a rotation speed sensor (crank angle sensor) 43 for detecting the engine rotation speed.

  Outputs of these various sensors are input to the ECU 50, and the ECU 50 executes various processes based on these sensor inputs. Specifically, the ECU 50 is configured mainly with a microcomputer, and executes various engine control programs recorded in a built-in ROM, thereby performing air-fuel ratio control, variable valve timing control, throttle opening control. Various engine controls such as idle speed control are realized. Hereinafter, an example in which the present invention is applied to air-fuel ratio control will be described more specifically.

(2) Outline of Air-Fuel Ratio Control In the vehicle control system 1 of the present embodiment, the reciprocal 1 / λ _T of the target air-fuel ratio λ _T that is the target value of the air-fuel ratio λ is used as the control target (target value r) to enter the operating state. The target value r is switched accordingly, and based on the target value r and the actual air-fuel ratio (actual air-fuel ratio) λc detected by the air-fuel ratio sensor 39 (specifically, the reciprocal 1 / λc of the actual air-fuel ratio λc is controlled by the control amount y Based on the control amount y), the fuel injection amount of the injector 27 is adjusted to realize air-fuel ratio control. Specifically, in the present embodiment, air-fuel ratio control is realized by a two-degree-of-freedom air-fuel ratio control system in which a feedback control system is combined with a feedforward control system.

The most characteristic configuration in the air-fuel ratio control system of the present embodiment is the configuration of the feedforward control system. That is, the feedforward control system of the present embodiment uses a feedforward manipulated variable (FF manipulated variable) that is a feedforward term in the control law based on the differential value of the target value r without using a transfer function model to be controlled. The calculation of u _ff is a first characteristic configuration. Also, regarding the differentiation of the target value r, the target value r is not differentiated as it is, but the target value r is smoothed and the smoothed target value rfilt calculated by the smoothing process is differentiated. It has a characteristic configuration.

In the air-fuel ratio control system of the present embodiment, the target value r is calculated and the control amount y is obtained at every calculation timing of a predetermined period, and the FF manipulated variable u _ff and the FB manipulated variable (feedback manipulated variable) are obtained based on them. ) to calculate the u _fb, finally calculates the operation amount ufinal input to the plant using these. Then, a fuel injection command corresponding to the calculated operation amount ufinal is input to the injector 27, so that an amount of fuel corresponding to the operation amount ufinal is injected from the injector 27.

  Specifically, the air-fuel ratio control system of this embodiment can be represented by a functional block diagram as shown in FIG. The functional block diagram of FIG. 2 is a block diagram showing the functions of the air-fuel ratio control system performed by the ECU 50 (specifically, realized by the microcomputer in the ECU 50 executing the injector driving process (see FIG. 3)). It is a representation.

That is, as shown in FIG. 2, the air-fuel ratio control system of the present embodiment performs the target value r (i) by smoothing the target value r (i). a target value smoothing processing unit 61 for calculating i), an FF manipulated variable calculating unit 62 for calculating an FF manipulated variable u _ff (i) based on the smoothed target value rfilt (i), and a smoothed target value rfilt Based on (i), the FB manipulated variable calculator 63 that calculates the FB manipulated variable u _fb , the other correction calculator 64 that calculates the manipulated variable correction value uother, the FF manipulated variable u _ff , the FB manipulated variable u _fb, and the manipulated variable An operation amount calculation unit 65 that calculates an operation amount ufinal by adding three of the amount correction values uother is provided. Thereby, in the control object (plant) 66, fuel injection corresponding to the input operation amount ufinal is executed, and a control output (control amount) y is output for the operation amount ufinal.

  The actually obtained control output is the air-fuel ratio λ, which is a measured value of the air-fuel ratio sensor 39. In the air-fuel ratio control system of this embodiment, the reciprocal of the measured air-fuel ratio λ (fuel excess ratio). Is used for feedback control as a control amount y. Further, “i” indicates the cumulative number (number of times of calculation) of calculation timings that are discretely generated from a certain reference timing (for example, the first calculation timing after the start of control).

  The target value r (i) is generated by a target value generation function that the ECU 50 has. The ECU 50 calculates a target value r (i) using a map or the like according to various engine states such as the engine speed and the accelerator opening at each calculation timing. That is, the target value r (i) is calculated stepwise.

The target value smoothing processing unit 61 performs a smoothing process on the target value r (i) at each calculation timing, and smoothes the result (that is, the result of the target value r (i) being smoothed). The target value rfilt (i) is output. The annealing process is a process of smoothing a change in the actual target value r (i) and using the smoothed value as a target value (an annealing target value) used for the operation amount calculation. In the present embodiment, j-time smoothing processing is performed from the first smoothing processing to the j-th (j is a natural number of 2 or more) smoothing processing at each calculation timing. An n-annealed value r _n (i) (n = 1 to j) is calculated.

Specifically, first, the target value r (i) calculated at the current calculation timing is set to r ₀ (1) as in the following formula (1).

  Then, the smoothing process is sequentially executed by j operations from Expression (2) to Expression (4).

That is, the first first smoothing process according to the above equation (2) is performed by using the target value r (i) (= r ₀ (i)) acquired at the current calculation timing and the previous calculation timing. The first smoothed value r ₁ (i) is calculated by weighting and adding the first smoothed value r ₁ (i−1) calculated in step 1 with the first smoothing coefficient α ₁ .

When the first smoothed value r ₁ (i) is calculated, a second second smoothing process according to the above equation (3) is then performed using the first smoothed value r ₁ (i), and the second smoothing value r ₁ (i) is calculated. The preferred value r ₂ (i) is calculated. This second smoothing process includes the first smoothed value r ₁ (i) calculated by the expression (2) and the second smoothed value r ₂ (i calculated by the second smoothing process at the previous calculation timing). -1) is weighted and added with the second smoothing coefficient α ₂ . Similarly, the smoothing process is repeated sequentially from the third time to the jth time.

That is, in the n-th annealing process for the n-th time after the second time, the ( _n-1 ) _-th annealing value r _n-1 (i ) And the nth smoothed value r _n (i−1) calculated by the nth smoothing process at the previous calculation timing, and the nth smoothed value by weighting and adding with the nth smoothing coefficient α _n . to calculate the r _n (i). As a result, the j-th j-th annealing process is finally performed in equation (4) above, and the j-th annealing value r _j (i) is calculated.

The jth smoothing value r _j (i) finally calculated by performing _j smoothing processes in this way is set as the smoothing target value rfilt (i) as shown in the following formula (5). .

The annealing coefficient α _n determines the strength (weight) of the annealing, and can be appropriately determined within the range of 0 ≦ α _n <1. The greater the smoothing coefficient α _n , the greater the smoothing effect.

Therefore, by appropriately setting the number j of the annealing processes and the respective smoothing coefficients α _n in each of the annealing processes, it is possible to finely set the effect of the annealing and obtain a desired annealing effect. It becomes like this.

The FF manipulated variable calculator 62 calculates the FF manipulated variable u _ff (i) using the smoothed target value rfilt (i) calculated by the target value smoothing processor 61.
That is, first, the target value differential calculation unit 71 performs differential calculation of the smoothed target value rfilt (i). In addition, since the air-fuel ratio control system of this embodiment is performed by discrete processing (digital processing) at each calculation timing, the differentiation in this embodiment is the difference from the previous calculation timing to the current calculation timing. This means a process of dividing by the interval Δt.

In the differential operation of the present embodiment, the smoothed target value rfilt (i) is m-order differentiated. Therefore, the target value differential calculation unit 71 calculates differential value d ¹ (i) to d ^m (i) for differential calculation, which is a differential value in differential calculation of each floor, as shown in the following formulas (6) to (8). To do. In the following formulas (6) to (8), the number attached to “d” indicates the rank of differentiation. This differential rank m can be determined as appropriate.

Then, the FF manipulated variable calculation processing unit 72 uses the calculated differential value d ¹ (i) to d ^m (i) for each floor, the time interval Δt, and the smoothing target value rfilt (i). The FF manipulated _variable u _ff (i) is calculated by the following equation (9).

In addition, each coefficient k and FF _{1 to} FF _m of each term on the right side in the above equation (9) can be determined as appropriate.
The FB manipulated variable calculator 63 calculates the FB manipulated variable u _fb (i) using the smoothed target value rfilt (i) calculated by the target value smoothing processor 61. Specifically, at each calculation timing, the target delay unit 76 delay-calculates the smoothing target value r (i), so that the smoothing target value rfilt (i−w) at the previous calculation timing is obtained as the feedback target value. Output as yr (i). Then, the deviation calculator 77 calculates a difference e (i) between the feedback target value yr (i) and the control amount y (i), and the FB manipulated variable calculation processor 78 calculates the difference e (i). The FB operation amount u _fb (i) is calculated by executing the PID control calculation based on it. More detailed calculation processing of the FB operation amount calculation unit 63 will be described later with reference to FIG.

  Note that w indicates a dead time. That is, in the air-fuel ratio control system of the present embodiment, the fuel injection command based on the smoothing target value rfilt (i) calculated at a certain calculation timing is output until the control amount y reflecting it is observed. Since there is a certain time difference, the dead time w is set in consideration of the time difference. The dead time w of the present embodiment is obtained by converting the above time difference into an integer based on the calculation cycle (a numerical value representing an integer multiple of the calculation cycle).

The other correction calculation unit 64 performs various corrections for the respective operation amounts u _ff (i) and u _fb (i). For example, the other correction calculation unit 64 performs a predetermined calculation based on the engine coolant temperature, the vehicle acceleration state, and the like. An operation amount correction value uother is calculated at every predetermined timing.

The operation amount calculation unit 65 includes an FF operation amount u _ff (i) calculated by the FF operation amount calculation unit 62, an FB operation amount u _fb (i) calculated by the FB operation amount calculation unit 63, and other corrections. The operation amount ufinal is calculated by adding the operation amount correction value uother calculated by the calculation unit 64.

(3) Description of Injector Drive Control Process Next, the injector drive control process executed by the ECU 50 to realize the function of the air-fuel ratio control system of FIG. 2 described above will be described with reference to FIG. In the following description, for simplification of description, in the generation of the FF manipulated _variable u _ff (i), the smoothing process is performed twice (that is, j = 2), and the differential operation is performed by the first-order differentiation (that is, m = 1) is described as an example.

When the microcomputer of the ECU 50 starts the injector drive control process at every calculation timing, first, in S110, the microcomputer calculates a target value r (i) from the engine state. The target value r (i) calculated here is the reciprocal of the target air-fuel ratio λ _T (i).

  In S120, the smoothing target value rfilt (i) is calculated by performing the smoothing process on the target value r (i) calculated in S110. Specifically, the annealing process is performed sequentially (twice in this example) according to the procedures shown in the following formulas (10) to (12).

Then, the second smoothed value r ₂ (i) calculated in the second smoothing process (Formula (12)) is calculated as the smoothed target value rfilt (i) as shown in the following Formula (13). .

In S130, in order to differentiate the smoothing target value rfilt (i), the differential value d ¹ (i) for differentiation calculation is calculated by the following equation (14).

In S140, the FF manipulated _variable u _ff (i) is calculated by the following equation (15).

  In S130, the calculation of the second term on the right side of the above equation (15) may be completed (that is, the differential calculation is completed), that is, the target value differential calculation in the functional block diagram of FIG. It goes without saying that the differential calculation may be completed by dividing each differential calculation difference value by the time interval Δt in the unit 71.

After calculating the FF manipulated _variable u _ff (i) in this way, the FB manipulated _variable u _fb (i) is calculated in S150. Details of the FB manipulated variable calculation process in S150 are as shown in FIG.

  That is, first, in S210, the actual air-fuel ratio λc, which is a measured value of the air-fuel ratio sensor 39, is read. In S220, the reciprocal of the read actual air-fuel ratio λc is set as a control amount y. In S230, the smoothing target value rfilt (i) calculated in S120 is read.

Based on the read control amount y and the smoothing target value rfilt (i), a control amount deviation is calculated in S240.
Specifically, first, as shown in the following equation (16), in consideration of the dead time w, the smoothing target value rfilt (i−w) at the calculation timing before w times is set to the feedback target value yr (i). Calculate as

Then, a first deviation e (i) that is a difference between the feedback target value yr (i) and the control amount y (i) is calculated by the following equation (17), and the first deviation e (i) is calculated by the following equation (18). A deviation first-order differential value de (i), which is a differential value of the deviation e (i), is calculated, and further, a deviation double-differential value d ² e that is a second-order differential value of the first deviation e is calculated by the following equation (19). (I) is calculated. The dead time w can be set to 7 as described above, for example. Δt is the time interval.

In S250, the FB manipulated variable increment value Δu _fb (i) is calculated by the following equation (20). In addition, each coefficient of each term on the right side of Expression (20) can be determined as appropriate.

In S260, the FB operation amount increment Δu _fb (i) calculated in S250 is added to the FB operation amount u _fb (i−1) calculated at the previous calculation timing by the following equation (21). The current FB operation amount u _fb (i) is calculated.

When the FB manipulated variable u _fb (i) is calculated in this way, the manipulated variable correction value uother is calculated in the subsequent S160 (FIG. 3).
In S170, the operation amount ufinal is calculated by the following equation (22), and a fuel injection command based on the calculated operation amount ufinal (i) is output to the injector 27, thereby driving the injector 27.

(4) Effects of Embodiment, etc. According to the vehicle control system 1 of the present embodiment described above, the target value r (i) is differentiated after being smoothed, the smoothed target value rfilt (i) and its The FF manipulated variable u _ff (i) is calculated using the differential value. Specifically, the FF manipulated variable u _ff (i) is calculated by adding the smoothed target value rfilt (i) and the differential value after multiplying each by a predetermined coefficient.

Therefore, even if the change of the target value r (i) is large (even if it changes stepwise), it is possible to prevent the differential value from becoming excessive, and the target value r (i) is not required to model the control target. ), The generation of the FF manipulated variable u _ff (i) based on the target value r (i) can be easily realized with appropriate and low man-hours.

  As for the smoothing process of the target value r (i), the smoothing target value rfilt (i) is calculated by performing the smoothing process on the target value r (i) a plurality of times (twice in the above example). I have to. Thus, a larger smoothing effect can be obtained by multiplying the target value r (i) a plurality of times. Further, by appropriately setting the number j of the annealing processes, a desired level of the annealing effect can be obtained, and the degree of freedom of the feedforward control is expanded.

Further, as a specific method of the annealing process, in this embodiment, the annealing process is performed a plurality of times by the method described in S120 of FIG. 3 (specifically, the method shown in the above formulas (1) to (5)). I am doing so. That is, first, the target value r (i) is smoothed to obtain the first smoothed value r ₁ (i), and the first smoothed value r ₁ (i) is further smoothed to obtain the second smoothing value. The final smoothing target value rfilt (i) is obtained by sequentially performing the smoothing process according to the procedure of obtaining the preferred value r ₂ (i). Therefore, by appropriately setting the number of times j of the annealing process and the weighting (smoothing coefficient α _n (n = 1 to j)) in each of the annealing processes, the desired level of the annealing effect can be more reliably ensured. The degree of freedom of feedforward control is further expanded.

Further, the smoothed target value rfilt (i) is subjected to multiple-order differentiation, and the differential value of each floor is used, so that a more appropriate FF manipulated variable u _ff (i) that reflects the change state of the target value r (i). Can be calculated. In addition, the degree of freedom of feedforward control can be further expanded by appropriately setting the differential rank m.

Here, the effect of combining the FF control system and the FB control system will be described with reference to the simulation results of FIGS.
First, FIG. 5 shows a comparison between the conventional control system having only the FB control system and the configuration of the present embodiment (a combination of the FF control system and the FB control system and the present invention is applied to the FF control system). The result is shown. When the target value r changes stepwise at time 1 second, the manipulated variable ufinal is excessively corrected due to the influence of the deviation of the target value r in the conventional method using only the FB control system, as shown in FIG. An operation is performed and the manipulated variable ufinal changes greatly. Therefore, the control amount y has an overshoot as shown in FIG.

On the other hand, in the case of the control system of the embodiment to which the present invention is applied, when the target value changes stepwise, the appropriate FF manipulated variable u _ff and FB manipulated variable u _{fb in the} FF control system and the FB control system, respectively. Is calculated.

Specifically, for the FF manipulated variable u _ff , as shown in FIG. _6A , an appropriate FF manipulated variable u _ff is calculated while suppressing an excessive change with respect to the step change of the target value. Yes. Thereby, as shown in FIG.6 (b), the contribution of FB control is suppressed small.

  Therefore, an appropriate operation amount ufinal is calculated as shown in FIG. Then, by controlling using the appropriate operation amount ufinal, as shown in FIG. 5A, the control amount y appropriately follows the target value r without overshoot.

  Further, as shown in FIG. 7, the compensation behavior for disturbance can be improved by combining the FB control with the FF control. That is, for example, as shown in FIG. 7A, it is assumed that a disturbance (for example, purge) of 0.1 occurs at 1 second in time. The target value is assumed to be 1.

  In this case, as shown in FIG. 7C, the manipulated variable ufinal is only the FF manipulated variable from the FF control system when there is no FB control, whereby the controlled variable y is shown in FIG. 7B. Thus, it becomes difficult to follow the target value 1. On the other hand, when the FB control is combined, the control amount y can quickly follow the target value 1 as shown in FIG. In other words, by constructing the FB control system with an appropriate feedback gain and combining it with the FF control system, it is possible to improve the follow-up to the target value more than when only the FF control system or only the FB control system. .

  By applying the present invention to an air-fuel ratio control system, even when the target air-fuel ratio fluctuates, it becomes possible to quickly follow the control amount (air-fuel ratio) to the target value. The performance is improved and the fuel efficiency is improved.

  In the present embodiment, the target value smoothing processing unit 61 corresponds to the smoothing processing means of the present invention, and the target value differentiation calculation unit 71 and the FF manipulated variable calculation processing unit 72 (division processing at the time interval Δt) are The FF manipulated variable calculation processing unit 72 corresponds to the differential means of the present invention, and the manipulated variable calculation means of the present invention. In the injector drive control process of FIG. 3, the process of S120 corresponds to the process executed by the annealing process means of the present invention, and the process of S130 to S140 (where S140 is the differential operation of the second term on the right side) is the present invention. The processing of S140 corresponds to the processing executed by the operation amount calculation means of the present invention.

[Modification]
Although the embodiments of the present invention have been described above, the embodiments of the present invention are not limited to the above-described embodiments, and can take various forms as long as they belong to the technical scope of the present invention. Needless to say.

  For example, in the above embodiment, the target value r (i) is smoothed by the method shown in the equations (1) to (5), but such a calculation method is merely an example, and the target value As long as the value r (i) can be appropriately rounded, various specific methods are conceivable.

  In the above embodiment, the example in which the present invention is applied to the air-fuel ratio control system has been described. However, the application of the present invention is not limited to the air-fuel ratio control system, and the FF control system is provided or is controlled. The present invention can be applied to any control system to which a system can be added, and is particularly suitable for an FF control system in which the target value changes stepwise.

  DESCRIPTION OF SYMBOLS 1 ... Vehicle control system, 10 ... Engine, 13 ... Intake pipe, 15 ... Air cleaner, 17 ... Air flow meter, 19 ... Motor, 20 ... Throttle valve, 21 ... Throttle opening sensor, 23 ... Intake pipe pressure sensor, 25 ... Intake Manifold 27 ... Injector 29 ... Spark plug 31 ... Intake valve 32 ... Exhaust valve 33,34 ... Variable valve timing adjustment mechanism 35 ... Exhaust pipe 37 ... Catalyst 39 ... Air fuel ratio sensor 41 ... Water temperature sensor , 43 ... Rotational speed sensor, 50 ... ECU, 61 ... Target smoothing processing unit, 62 ... FF manipulated variable computing unit, 63 ... FB manipulated variable computing unit, 64 ... Other correction computing unit, 65 ... manipulated variable computing unit, 66 ... Control target (plant), 71 ... Target value differential calculation unit, 72 ... FF manipulated variable calculation processing unit, 76 ... Target delay unit, 77 ... Deviation calculation unit, 78 ... FB operation The amount calculation processing unit

Claims (6)

A feedforward control method for feedforward control of an object to be controlled,
At each predetermined calculation timing, the target value at that calculation timing is acquired, and the target value that has been smoothed is calculated by performing an annealing process on the acquired target value. ,
A target value differential value is calculated by differentiating the smoothing target value calculated by the annealing process,
A feedforward manipulated variable is calculated by a predetermined arithmetic expression using the smoothing target value and the target value differential value,
The control object is controlled using the calculated feedforward manipulated variable. A feedforward control method characterized by: A feedforward control device that performs feedforward control of a controlled object,
At each predetermined calculation timing, a target value at the calculation timing is acquired, and an annealing target value is calculated by performing an annealing process on the acquired target value. Annealing means,
Differentiating means for calculating a target value differential value by differentiating the smoothing target value calculated by the annealing processing means;
An operation amount calculation means for calculating a feedforward operation amount by a predetermined arithmetic expression using the smoothing target value and the target value differential value;
The feedforward control device is characterized in that the control target is controlled using the feedforward operation amount calculated by the operation amount calculation means. The feedforward control device according to claim 2,
The operation amount calculation means calculates the feed forward operation amount by adding the smoothed target value and the target value differential value after multiplying each by a predetermined coefficient, respectively. . A feedforward control device according to claim 2 or claim 3,
The said smoothing process means calculates the said smoothing target value by performing the said smoothing process with respect to the acquired said target value in multiple times. The feedforward control apparatus characterized by the above-mentioned. The feedforward control device according to claim 4,
The annealing processing means is:
At each arithmetic timing, j-th smoothing is performed from the first smoothing to j-th (j is a natural number of 2 or more) smoothing, and the nth smoothing value is sequentially performed for each round of smoothing. Configured to calculate (n = 1 to j),
In the first first smoothing process, the target value acquired at the current calculation timing and the first smoothed value calculated in the first smoothing process at the previous calculation timing are weighted and added. Calculating the first annealing value;
In the second and subsequent n-th annealing processes, the n-1th annealing value calculated in the (n-1) -th annealing process, which is the (n-1) -th annealing process, and the previous calculation timing, respectively. Calculating the nth smoothing value by weighting and adding the nth smoothing value calculated in the nth smoothing process;
The feedforward control apparatus, wherein the jth smoothing value calculated in the last jth smoothing process is calculated as the smoothing target value. The feedforward control device according to any one of claims 2 to 5,
The feedforward control device, wherein the differentiating means performs m-th order differentiation (m is a natural number of 2 or more) of the smoothing target value, and calculates a differential value of each floor as the target value differential value.

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