JP2004021309A - Pid control device, program and recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To let a control object attain to a target value rapidly and smoothly in a PID control device which executes control from a present value to a final target value by applying a PID control to the control object. <P>SOLUTION: The PID control device does not execute the PID control toward the final target value C from the beginning but executes control toward a first target value A and a second target value B, which are separately set, before the final target value C is attained, and finally lets the control object attain the final target value C. Each of the first and second target values A and B is set to a value smaller by a permissible set value preliminarily determined from the final target value C, respectively so that an overshoot does not occur to the final target value C. Accordingly, a starting speed control for a vehicle can rapidly be started up, and a convergent time to the final target value C can be reduced, and the stable PID control which prevents the occurrence of the overshoot can be realized. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a PID control device that controls a control target from a current value to a final target value by performing PID control on the control target.
[0002]
Problems to be solved by the prior art and the invention
Conventionally, for example, as a control for stably bringing a control target such as a vehicle speed, an acceleration or a furnace temperature to a certain target value, a deviation between the target value and the current value of the control target is proportionally, integrated, and differentiated, PID control for controlling a current value to match a target value is widely performed.
[0003]
For example, as shown in the graph of FIG. 9, when the vehicle speed as a target value is set in the cruise control of the vehicle, the deviation between the target value and the current value detected by the vehicle speed sensor is subjected to proportional / integral / differential processing. For example, a fuel injection amount as a control amount is calculated, and this is output as a control command signal. Then, the injection speed of the injector is controlled in accordance with the control command signal to control the vehicle speed.
[0004]
However, in such conventional PID control, only one target value is set, and control is performed with respect to the one target value. Therefore, there are the following problems.
That is, first, it is desired that the controlled object quickly reach the target value from the current value. For this purpose, if the integral term (I term) is set to be large, for example, the vehicle speed changes abruptly, which may cause a shock to the vehicle. . Also, as shown in an exaggerated manner in the figure, the vehicle speed fluctuates and hunting occurs, and in some cases, an overshoot exceeding a target value is caused in the control process, and the driver's feeling is impaired due to a sudden approach to the preceding vehicle. There is a problem that there is a fear.
[0005]
Conversely, if the integral term (I term) is set small, for example, to prevent such a rapid change or overshoot of the vehicle speed, it takes time until the vehicle speed reaches the target value, and control is delayed. There was a problem.
Such a problem occurs not only in cruise control but also in various controls using other vehicle speed control, acceleration control, or PID control such as temperature control.
[0006]
The present invention has been made in view of such a problem, and in a PID control device that controls a control target from a current value to a final target value by performing PID control on the control target, the control target reaches the target value quickly and smoothly. The purpose is to be able to do.
[0007]
[Means for Solving the Problems]
In view of the above problem, a PID control device according to claim 1 controls a control target from a current value to a final target value by performing PID control on the control target. , One or more intermediate target values smaller than the final target value are set stepwise so as to approach the final target value.
[0008]
Here, the "control target" means various control targets to which PID control is applied, such as the speed and acceleration of a moving body including a vehicle, the temperature of a furnace, and the like. The “current value” means the current state of the control target, and is detected by detection means such as a sensor. Further, the “final target value” corresponds to the “target value” in the above-described conventional technology. However, an intermediate target value is set between the current value and the target value. It is expressed in this way for distinction. This “final target value” is calculated by the PID control device itself, or is input as a control target value from the outside.
[0009]
Then, the control means controls each of the intermediate target values set by the target value setting means as a control target so that the control target gradually approaches the final target value.
According to this configuration, the control is not performed from the beginning to the final target value, but is performed toward the intermediate target value set until the final target value is reached. Will be reached. For this reason, it is possible to effectively suppress or prevent the occurrence of overshoot, control delay, and the like that occur when the final target value is directly set as the control target. That is, since the intermediate target value (when there are a plurality of intermediate target values, the first intermediate target value in particular) is set to a value smaller than the final target value, it is assumed that this intermediate target value is used as a control target value to perform sudden control. Even if the control target exceeds the intermediate target value, it is possible to suppress or prevent the control target from exceeding the final target value. Therefore, quick PID control is performed so as to quickly reach the intermediate target value, so that the final target value can be reached in a short time, and the occurrence of overshoot can be effectively suppressed or prevented.
[0010]
In order to reliably prevent overshoot, in the PID control device according to claim 2, the target value setting means sets each intermediate target value so as not to overshoot the final target value. A value smaller than the final target value by a predetermined allowable set value is set.
[0011]
As the "permissible set value" here, the magnitude of the hunting (amplitude of the pulsation in the control state) is empirically determined for each control target, and a value equal to or greater than the magnitude is set in advance. For this reason, the allowable set value may be different if the control target or the setting of the intermediate target value is different.
[0012]
According to such a configuration, the control state (current value) is always lower than the final target value to reliably prevent overshoot and realize safe PID control.
Further, the above-described PID control can be performed with the control constants of the proportional, integral, and differential fixed. However, by using an appropriate control constant for each intermediate target value, the control efficiency can be further increased. It is thought that it is possible.
[0013]
Therefore, as described in claim 3, the control constant setting means does not overshoot the final target value and converges from the current value to the final target value within a predetermined convergence period. A PID control constant may be set for each intermediate target value.
[0014]
According to such a configuration, it is possible to independently control up to each intermediate target value. That is, for example, the rise of the control up to the intermediate target value closest to the current value is increased, and then the other intermediate target value and the final target value are gently controlled, or the control is performed in a reverse manner. It can be set and the convergence time can be adjusted accordingly, and PID control according to the designer's intention can be realized.
[0015]
Further, when the control target approaches the final target value, the possibility of occurrence of overshoot increases, so that it may be preferable to perform more gradual control to prevent the overshoot.
Therefore, as described in claim 4, the control means sets the control target to the final target value between the intermediate target value set by the target value setting means and the intermediate target value closest to the final target value. The gradual change control may be performed so that the control target gradually approaches the final target value so as not to overshoot the value.
[0016]
The “gradual change control” here may be realized by setting any one of the proportional, integral, and differential control constants of the PID control to zero, or performing a completely different control instead of the PID control only for that part. It may be.
According to such a configuration, the control target can be gradually approached to the final target value, overshoot can be almost certainly prevented, and smooth and stable control can be realized.
[0017]
Further, for example, when the control target is the speed of the vehicle, the responsiveness to the target value may change depending on the weight of the vehicle and the traveling environment. In other words, when the load of the vehicle is large, the controllability of the control to the target value is inferior to that when the load is small, and the responsiveness may be reduced. In addition, when traveling on an uphill lane, responsiveness may be lower than when traveling on level ground. This is not limited to the case where the control target is the speed of the vehicle, but the same can be said in the case where there is a factor that becomes a load (resistance) of the control target.
[0018]
Therefore, as set forth in claim 5, the detecting means detects the load to be controlled, and the target value setting means sets each intermediate target value to the final target value as the load detected by the detecting means increases. You may make it set to the side approaching a value.
That is, when the load is large, the responsiveness is ensured by setting an apparent intermediate target value larger (higher) than the normally set intermediate target value. Accordingly, the control is performed in the same manner regardless of the situation of the control target, so that it is possible to suppress or prevent the user from feeling uncomfortable or the like.
[0019]
From such a viewpoint, the same effect can be obtained by changing the control constant instead of changing each intermediate target value as described above.
That is, as set forth in claim 6, the detecting means detects the load of the control object, and the control constant setting means sets the PID control constant and the control object as the load detected by the detecting means increases. You may make it set to the side approaching a final target value.
[0020]
According to this configuration, as the load is larger, the PID control constant is set in a direction in which the control is performed more steeply, so that a decrease in responsiveness can be suppressed or prevented.
The function of realizing each unit of the PID control device by a computer can be provided, for example, as a program activated on the computer side. In the case of such a program, for example, it can be used by recording it on a computer-readable recording medium such as an FD, MO, DVD, CD-ROM, or hard disk, and loading and activating the computer as needed. Alternatively, the program may be recorded on a ROM or a backup RAM as a computer-readable recording medium, and the ROM or the backup RAM may be incorporated in a computer.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
[First embodiment]
In this embodiment, the PID control device of the present invention is applied to a cruise control device of a vehicle, and FIG. 1 is a block diagram showing a schematic configuration of the cruise control device.
[0022]
As shown in FIG. 1, a cruise control device 1 includes an electronic control device for inter-vehicle control (hereinafter referred to as “inter-vehicle control ECU”) 2, an electronic control device for engine control (hereinafter referred to as “engine ECU”) 6, and a brake electronic control. The apparatus (hereinafter, referred to as “brake ECU”) 4 is mainly configured.
[0023]
The inter-vehicle control ECU 2 is an electronic circuit mainly composed of a microcomputer. The inter-vehicle control ECU 2 receives a current vehicle speed signal, a steering angle signal, a yaw rate signal, a target inter-vehicle time signal, a control state signal for idle control and brake control, and the like from the engine ECU 6. I do. The inter-vehicle control ECU 2 estimates the radius of curvature R of the curve or performs inter-vehicle control calculation based on the received data.
[0024]
The laser radar sensor 3 is an electronic circuit mainly composed of a scanning distance measuring device using a laser and a microcomputer. The laser radar sensor 3 detects the angle and relative speed of the preceding vehicle detected by the scanning distance measuring device, and the distance control ECU 2. Based on the received current vehicle speed signal, curve curvature radius R, and the like, the own lane probability of the preceding vehicle is calculated and transmitted to the following distance control ECU 2 as preceding vehicle information including information such as relative speed.
[0025]
Further, the inter-vehicle control ECU 2 determines a preceding vehicle to be inter-vehicle controlled based on the own lane probability or the like included in the preceding vehicle information received from the laser radar sensor 3 in this manner, and appropriately adjusts the inter-vehicle distance with the preceding vehicle. A target vehicle speed signal, a fuel cut request signal, a brake request signal, and the like are transmitted to the engine ECU 6 as control command values for performing the control. The brake ECU 4 is an electronic circuit mainly composed of a microcomputer, and includes a steering sensor 8 for detecting a steering angle of the vehicle, a yaw rate sensor 10 for detecting a yaw rate as a turning state of the vehicle, and a speed of each wheel. The steering angle and the yaw rate are obtained from the wheel speed sensor 12 and the data are transmitted to the inter-vehicle control ECU 2 via the engine ECU 6. The brake ECU 4 opens and closes a pressure increasing control valve and a pressure reducing control valve provided in a brake hydraulic circuit in order to control a braking force according to a braking request based on a target speed or the like from the headway control ECU 2 via the engine ECU 6. Of the brake actuator 25 that controls the duty of the brake actuator.
[0026]
The engine ECU 6 is an electronic circuit mainly composed of a microcomputer, and includes an accelerator pedal sensor 15 for detecting an amount of depression of an accelerator pedal, a vehicle speed sensor 16 for detecting a vehicle speed, and a brake for detecting the presence or absence of depression of a foot brake. It receives detection signals and the like from the switch 18, the cruise control switch 20, the cruise main switch 22, and other sensors and switches, and further receives various signals from the brake ECU 4 and the following control ECU 2.
[0027]
The engine ECU 6 drives the injector 24 that adjusts the fuel injection amount of the internal combustion engine (here, a gasoline engine), the actuator drive stage of the transmission 26, and the like in accordance with the operating state determined from the received signal. Outputting instructions. With these actuators, it is possible to control the output, the braking force, or the shift shift of the internal combustion engine.
[0028]
Next, a vehicle speed control method in the cruise control device of the present embodiment will be described. The vehicle speed control is realized by PID control by the engine ECU 6 that has received the target vehicle speed signal output from the headway control ECU 2. 2 and 3 are explanatory diagrams showing the vehicle speed control method.
[0029]
In the vehicle speed control, first, the engine ECU 6 receives a target vehicle speed (hereinafter, also referred to as a “final target value C”) transmitted as a control target value from the headway control ECU 2 and a current vehicle speed (hereinafter, also referred to as “final target value C”) detected by the vehicle speed sensor 16. Hereinafter, also referred to as “current value”).
[0030]
Then, as shown in FIG. 2, first, a first target value A and a second target value B, which are smaller than the final target value C, are interposed between the current value and the final target value C in this order. It is set stepwise so as to approach C. At this time, each of the first target value A and the second target value B does not overshoot the final target value C even if the current vehicle speed pulsates during the PID control (see FIG. 9). Each is set to a value smaller than the final target value C by a predetermined allowable set value. The allowable set value is set in advance based on experience or the like. In the present embodiment, the allowable set value ΔV1 of the first target value A is set to 10 km / h, and the allowable set value ΔV2 of the second target value B is set. Is set to 3 km / h. The time from the current value to the final target value C is set so as to be within a predetermined time T.
[0031]
FIG. 3 is an explanatory diagram illustrating a specific method of the PID control performed by the engine ECU 6. The first target value A and the second target value B set based on the final target value C output by the headway control ECU 2. This shows an example in which the PID control calculation is performed, the result is converted into a fuel injection amount Q as a control command value, and the result is output to the injector 24 to perform fuel injection control. FIG. 1A is a control block diagram of PID control, and FIGS. 2B and 2C are control of a proportional term (P term), an integral term (I term), and a differential term (D term). It is explanatory drawing showing an example of a mode. Note that the “target value” shown in FIG. 3A does not indicate the final target value C output from the headway control ECU 2 but the first target value C set by the engine ECU 6 corresponding to the final target value C. Refers to the first target value A or the second target value B. In the graphs shown in FIGS. 3B and 3C, the horizontal axis represents the deviation Δ between the target value and the current value, and the vertical axis represents the magnitudes of the P, I, and D terms that contribute to the fuel injection amount. Represents
[0032]
As shown in FIG. 3A, first, a deviation Δ between each target value and the current value is taken, and the deviation Δ is proportionally processed by the P term, integrated by the I term, and differentiated by the D term. A fuel injection amount Q is calculated as a control instruction value by adding the converted values Q1, Q2, and Q3 to the fuel injection amount, and a control instruction signal is output to the injector 24 so as to inject the fuel injection amount Q.
[0033]
In the present embodiment, as shown in FIG. 3B, until the current value reaches the first target value A, the P and I terms are set to be larger than in the conventional case where no intermediate target value is set. (To increase the amount of change). The D term is left as it is. Then, as shown in FIG. 2, the vehicle speed is largely increased in the area (1).
[0034]
Until the current value exceeds the first target value A and reaches the second target value B, as shown in FIG. 3C, the P term and the I term are more gradual than when there is no intermediate target value. Set to be. The D term is left as it is. Then, as shown in FIG. 2, the vehicle speed is gradually increased in the area (2).
[0035]
Further, although not shown, until the current value exceeds the second target value B and reaches the final target value C, the P term and the I term are set so as to be more gentle than when there is no intermediate target value. The D term is left as it is. Then, as shown in FIG. 2, the vehicle speed is more gradually increased in the area (3) to reach the final target value C.
[0036]
As described above, according to the cruise control device 1 of the present embodiment, the engine ECU 6 performs the PID control from the beginning to the final target value C based on the final target value C transmitted from the headway control ECU 2. Instead, control is performed toward the first target value A and the second target value B separately set by the engine ECU 6 until the final target value C is reached, so that the final target value C is finally reached. become.
[0037]
Further, each of the first target value A and the second target value B is set to a value smaller than the final target value C by a predetermined allowable set value so as not to overshoot the final target value C. I have.
For this reason, even if the current value exceeds the first target value A even if the current value exceeds the first target value A, the control is performed so that the first target value A, which is the first intermediate target value, as the control target value is quickly reached. Exceeding the target value C can be prevented. For this reason, it is possible to realize a stable PID control in which the rise of the first vehicle speed control is made quick to shorten the convergence time to the final target value C, and the occurrence of overshoot is prevented.
[0038]
Further, according to the cruise control device 1, in the control to reach each of the first target value A, the second target value B, and the final target value C, the PID control constant is individually set, and a more appropriate control curve is set. I can draw. Therefore, it is possible to realize PID control that does not give the occupant a sense of discomfort such as a shock.
[0039]
In this embodiment, the engine ECU 6 corresponds to a target value setting unit, a control unit, and a control constant setting unit.
[Second embodiment]
The present embodiment relates to a PID control device capable of changing the setting of the intermediate target value based on the weight (load) of the vehicle, and is applied to a cruise control device of the vehicle as in the first embodiment. The configuration of the cruise control device of this embodiment is the same as that of FIG. 1 except that a weight sensor for newly detecting the vehicle weight is installed and the vehicle weight is output to the engine ECU 6. Since it is the same as that of the first embodiment, the description is omitted. FIG. 4 is an explanatory diagram showing a specific method of PID control at this time, and FIG. 5 is a flowchart showing PID control processing at this time.
[0040]
As shown in FIG. 4A, in the PID control according to the present embodiment, the final target value C transmitted from the headway control ECU 2 is determined based on the first target value A and the second target value B set as intermediate target values. Each of them is multiplied by a gain coefficient (GAIN) to adjust the setting based on the vehicle weight.
[0041]
That is, as conceptually shown in FIG. 3B, when the vehicle weight becomes larger than the normal weight due to the load, for example, the gain coefficient is increased with respect to the first target value A (open circle) as a reference. To set the first adjustment target value A2. Then, the deviation Δ between the first adjustment target value A2 and the current value is taken, and the deviation Δ is proportionally processed by the P term, integrated by the I term, and differentiated by the D term, and the fuel injection amount is calculated. The converted values Q1, Q2, and Q3 are added to calculate a fuel injection amount Q as a control command value, and a control command signal is output to the injector 24 so as to inject the fuel injection amount Q.
[0042]
FIG. 9C shows the setting of the PID control constant up to the first adjustment target value A2 as a specific example. That is, in the present embodiment, the relationship between the PID control constant and the deviation Δ is made the same as in the first embodiment, but by multiplying the gain coefficient in this manner, the deviation Δ itself becomes apparently large. Therefore, the fuel injection amount, which is the control command value, also increases.
[0043]
Next, a PID control process performed by the engine ECU 6 of the present embodiment will be described with reference to a flowchart of FIG.
As shown in the figure, first, a target vehicle speed signal transmitted from the headway control ECU 2 is received and set as a final target value C, and a first intermediate value which is a reference intermediate target value from the final target value C is set. A target value A and a second target value B are set (S110). Note that these target values are target values that are suitable when the vehicle travels on level ground, and are set in the same manner as in the first embodiment.
[0044]
Then, the gain coefficient a is set from the detected value of the vehicle weight by the weight sensor with reference to a predetermined map (not shown), and the first adjustment target value A2 and the first adjustment target value A2 are first determined by the function f (X) of the following equation (1). A second adjustment target value B2 is calculated (S120).
f (X) = aX (1)
f (X): adjustment target value
X: Vehicle-specific compatible value (standard intermediate target value)
a: Gain coefficient (fit value by weight)
Thereafter, PID control is performed using the first adjustment target value A2, the second adjustment target value B2, and the final target value C as control targets. That is, the current value detected by the vehicle speed sensor is compared with the first adjustment target value A2 (S130). If the current value is less than the first adjustment target value A2 (S130: NO), the first adjustment target PID control for the value A2 is performed (S140). When the current value reaches the first adjustment target value A2, the current value is compared with the second adjustment target value B2 (S150), and if the current value is smaller than the second adjustment target value B2. Performs (S150: NO), performs PID control toward the second adjustment target value B2 (S160). When the current value reaches the second adjustment target value B2, the current value is compared with the final target value C (S170). If the current value is smaller than the final target value C (S170). : NO), PID control toward the final target value C is performed (S180). Then, when the current value reaches the final target value C (S170: YES), a series of processing ends.
[0045]
As described above, according to the cruise control device of the present embodiment, the weight sensor detects the vehicle weight that is a load of vehicle running, and the larger the vehicle weight, the larger the gain coefficient and the larger the deviation Δ. As a result, control is performed to increase the fuel injection amount, which is the control command value.
[0046]
That is, when the vehicle weight is large, an apparent intermediate target value that is larger (higher) than the normally set intermediate target value is set, and the response is intentionally controlled in a direction to follow the intermediate target value. Have secured. However, the first adjustment target value A2 and the second adjustment target value B2 in the present embodiment are set so that the current values do not exceed the first target value A and the second target value B, which are the original intermediate target values, respectively. ing.
[0047]
With this configuration, even if the vehicle weight changes, the responsiveness does not significantly change, and as a result, it is possible to suppress or prevent the occupant from feeling uncomfortable or the like, and it is possible to improve drivability.
In this embodiment, the weight sensor corresponds to the detecting means.
[Third embodiment]
The present embodiment relates to a PID control device incorporating a gradual change control near the final target value, and is applied to a cruise control device for a vehicle as in the first and second embodiments. Note that the configuration of the cruise control device of this embodiment is the same as that of the first and second embodiments, and a description thereof will be omitted. FIG. 6 is an explanatory diagram showing the PID control method at this time, and FIG. 7 is an explanatory diagram showing the specific setting of the PID control constant at this time.
[0048]
As shown in FIG. 6, first, a first target value A3 and a second target value B3 are set, and control is performed so that the current value reaches the second target value B3. Note that the first target value A3 and the second target value B3 of the present embodiment are smaller than the first target value A and the second target value B of the first embodiment, respectively. Then, when reaching the second target value B3, a gradual change control for gradually increasing the vehicle speed toward the final target value C is executed.
[0049]
That is, as shown in FIG. 7, until the current value reaches the first target value A3 and the second target value B3, the P, I, and D terms of the PID control are controlled at a fixed rate. From the target value B3 to the final target value C, the P term and the D term are set to 0, and only the I term is set. Thus, as shown in FIG. 6, after the second target value B3, the vehicle speed gradually approaches the final target value C little by little.
[0050]
As described above, according to the cruise control device of the present embodiment, the control target can be gradually approached to the final target value, and smooth and stable control can be realized. The embodiments of the present invention have been described above. However, the embodiments of the present invention are not limited to the above-described embodiments, but may take various forms within the technical scope of the present invention. Nor.
[0051]
For example, in the above embodiments, two intermediate target values of a first target value and a second target value are set between the current value and the final target value C when the target value is output from the headway control ECU 2. However, the number of intermediate target values is not limited to two, and may be set to three or more, or conversely, only one may be set.
[0052]
Further, in the above-described embodiment, as shown in FIGS. 2 and 6, an example in which the vehicle speed is controlled to be greatly increased at the first first target value has been described. For example, as shown in FIG. It may be set so that it starts up slowly at first, and then starts up in the middle. In addition, various control modes can be adopted depending on the type of the control target.
[0053]
Further, in the second embodiment, an example in which each intermediate target value is multiplied by a gain coefficient based on the weight (load) of the vehicle has been described. For example, each allowable target value is multiplied by a gain coefficient to adjust each adjustment target value. May be set. That is, when the vehicle weight is large, an apparent allowable set value smaller than the normally set allowable set value is set, and the intermediate target value is relatively increased to intentionally control in a direction to follow the intermediate target value. Thus, the response can be ensured.
[0054]
Further, in the above-described embodiment, the mode in which the engine ECU 6 receives the control target value from the headway control ECU 2 has been described. However, the engine ECU is configured to also serve as the headway control ECU, and the engine ECU may calculate the control target value. Good.
Further, in each of the above-described embodiments, an example has been described in which the PID control device of the present invention is realized as a cruise control device. Of course, the device may be configured as the control.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a schematic configuration of a cruise control device (PID control device) according to a first embodiment of the present invention.
FIG. 2 is an explanatory diagram illustrating a PID control method according to a first embodiment.
FIG. 3 is an explanatory diagram illustrating a PID control method according to the first embodiment.
FIG. 4 is an explanatory diagram illustrating a PID control method according to a second embodiment.
FIG. 5 is a flowchart illustrating a PID control process according to a second embodiment.
FIG. 6 is an explanatory diagram illustrating a PID control method according to a third embodiment.
FIG. 7 is an explanatory diagram illustrating a PID control method according to a third embodiment.
FIG. 8 is an explanatory diagram illustrating a PID control method according to a modification.
FIG. 9 is an explanatory diagram showing a conventional PID control method.
[Explanation of symbols]
1. Cruise control device 2. Inter-vehicle control ECU
4 ... Brake ECU, 6 ... Engine ECU,
16 ... vehicle speed sensor, 24 ... injector

Claims (8)

In a PID control device that controls a control target from a current value to a final target value by performing PID control on the control target,
Between the current value and the final target value, between one or more intermediate target values smaller than the final target value, target value setting means for setting stepwise so as to approach the final target value,
Control means for controlling the control target so as to gradually approach the final target value, with each intermediate target value set by the target value setting means as a control target,
A PID control device comprising: The PID control device according to claim 1,
Wherein the target value setting means sets each of the intermediate target values to a value smaller than the final target value by a predetermined allowable set value so as not to overshoot the final target value. Control device. 3. The PID control device according to claim 1, further comprising: not overshooting the final target value, and converging within a predetermined convergence period from the current value to the final target value. A PID control device comprising a control constant setting means for setting a PID control constant for each of the intermediate target values. The PID control device according to claim 1,
The control means does not overshoot the control target from the intermediate target value set by the target value setting means to the final target value during a period from a value closest to the final target value to the final target value. As described above, the PID control device performs the gradual change control for gradually bringing the control target closer to the final target value. The PID control device according to any one of claims 1 to 4, further comprising a detection unit configured to detect a load of the control target,
The PID control device, wherein the target value setting means sets each of the intermediate target values closer to the final target value as the magnitude of the load detected by the detection means increases. 4. The PID control device according to claim 3, further comprising a detection unit that detects a load of the control target,
The PID control device, wherein the control constant setting means sets the PID control constant such that the controlled object approaches the final target value as the load detected by the detection means increases. A program for causing a computer to function as each unit of the PID control device according to claim 1. A computer-readable recording medium on which the program according to claim 7 is recorded.

Images