JP5961422B2 - Sliding mode controller - Google Patents

Description

  The present invention relates to a sliding mode control device.

  For example, some motorcycles are equipped with an electronically controlled throttle valve device that controls the throttle valve using DBW (Drive By Wire) technology. In the electronically controlled throttle valve device, the control amount of the DBW is feedback controlled so that the opening degree of the throttle valve becomes a desired target amount.

  Here, a typical example of feedback control is PID control. In PID control, a control target is controlled by deviation, integration, and differentiation between an output value and a target amount. However, in PID control, it is difficult to ensure control stability when a disturbance is applied. In addition, it is difficult to set the gain used to calculate the control input.

  Therefore, in recent years, a method for controlling the throttle valve using the sliding mode control has been proposed. In the sliding mode control, a switching function having a plurality of state quantities of a control target, for example, a throttle valve as a variable, is defined, and a plurality of state quantities are converged on a switching plane defined by the switching function. While constraining on the switching plane, it converges to an equilibrium point on the switching plane. Here, the equilibrium point is a point where each state quantity matches each target quantity. In sliding mode control, as long as the state quantity is converged on the switching plane, the state quantity is hardly affected by disturbances and the like, and each state quantity can be converged to the equilibrium point on the switching plane very stably. it can.

  For example, when sliding mode control of the throttle valve opening is performed, the actual throttle valve opening is set as the DBW control amount, and a control input that converges the control amount to the target amount is calculated for each predetermined control cycle. A drive command signal is output to the throttle valve actuator in response to the control input.

  By the way, in the controlled object model used for constructing the switching plane, there is a modeling error between the actual controlled object. For this reason, a plurality of state quantities may not be able to reach the switching plane. Therefore, conventionally, in order to converge a plurality of state quantities on the switching plane, by providing an integration term calculated using the integrated value of the value of the switching function in the control input, the steady-state deviation can be eliminated and the plurality of state quantities can be eliminated. The state quantity is converged on the switching plane.

JP2002-251205

However, in the past, since the integration term was calculated by adding the value of the switching function for each control cycle, the integration term becomes too large until the state quantity reaches the vicinity of the switching plane, and a plurality of states The amount sometimes overshooted. When the overshoot of the state quantity increases, it takes time to reach the switching plane again, and hunting is likely to occur. For this reason, in the conventional sliding mode control, it is difficult to quickly converge the throttle valve to the target opening.
The present invention has been made in view of such circumstances, and an object thereof is to improve convergence to a target amount in sliding mode control.

According to the present invention, the control amount is the target of the actuator that operates the control target member, the control amount detector that detects the result of operating the control target member by the actuator as the control amount, and the operation amount to be given to the actuator A sliding mode controller unit that calculates to match the amount, and the sliding mode controller unit converges the state quantity on a switching plane defined by a switching function having the state quantity of the control target member as a variable. The control input includes an integrated value based on the value of the switching function calculated by substituting the state quantity as an integrated component, and the integrated value is When both the change in the controlled variable and the value of the switching function are within a predetermined range for each, the integrated value calculated last time is Calculated by adding the value corresponding to the current of the switching function value, characterized in that the integrated value previously calculated between the current accumulated value when outside the range of variation of the control quantity is predetermined A sliding mode controller is provided.

Further, according to the present invention, when the value of the switching function is out of a predetermined range, the current integrated value is decreased by multiplying the previously calculated integrated value by a coefficient for decreasing the integrated value. A sliding mode control device according to claim 1 is provided.

Furthermore, according to the present invention, an actuator for operating a control target member, a control amount detector for detecting a result of operating the control target member with the actuator as a control amount, and an operation amount to be given to the actuator, And a sliding mode controller unit that calculates so as to match the target amount, and the sliding mode controller unit has the state quantity on a switching plane defined by a switching function having the state quantity of the member to be controlled as a variable. The control input is calculated so as to converge, and the control input includes an integrated value based on a value of a switching function calculated by substituting the state quantity as an integrated component, and the integrated value Is calculated the previous time when both the change in the control amount and the value of the switching function are within a predetermined range for each. Calculated by adding a value corresponding to the value of the current switching function to the calculated value, and when the value of the switching function is outside the predetermined range, the previously calculated integrated value for decreasing the integrated value A sliding mode control device is provided in which the value multiplied by is used as the current integrated value .

  According to the present invention, when either one of the change in the control amount or the value of the switching function is outside the predetermined range, the increase in the absolute value of the integrated component is suppressed, and therefore input to the control target device. It is possible to prevent the integrated component used for calculating the manipulated variable from becoming too large. Thereby, since overshoot is suppressed, the convergence to the target amount is improved.

FIG. 1 is a block diagram showing a schematic configuration of a sliding mode control apparatus according to an embodiment of the present invention. FIG. 2 is a flowchart of the process of the sliding mode controller unit in the sliding mode control apparatus according to the embodiment of the present invention. FIG. 3 is a flowchart of the reaching law input calculation process in the sliding mode control apparatus according to the embodiment of the present invention. FIG. 4 is a timing chart showing an example of processing in the sliding mode control apparatus according to the embodiment of the present invention.

The form for implementing this invention is demonstrated in detail below.
FIG. 1 shows a schematic configuration of a sliding mode control apparatus according to the present embodiment.
The electronic control device 1, which is a sliding mode control device, includes a target amount calculation unit 11 that calculates a target amount from an operation result when a result of operation of the input device 2 by the driver is input via the input detector 3, And a sliding mode controller unit 12 to which the output of the calculation unit 11 is connected. The output of the sliding mode controller unit 12 is connected to the control target device 13. Further, the control amount of the control target device 13 is fed back to the sliding mode controller unit 12 via the control amount detector 14.

As the input device 2, for example, there is a throttle grip of a motorcycle. The input detector 3 in this case is an accelerator position sensor that detects the operation amount of the throttle grip.
The target amount calculation unit 11 calculates the target amount of the control target device 13 based on the output of the input detector 3. The target amount is, for example, the opening of the throttle valve, and is calculated using a map or the like stored in advance in the target amount calculation unit 11.

  The sliding mode controller unit 12 includes a CPU (Central Processing Unit), a memory, and the like, and is functionally divided into a switching function calculation unit 21, a control input calculation unit 22, and an operation amount processing unit 23.

The switching function calculation unit 21 receives the target amount PR and the control amount PO, calculates the deviation amount e (k) by subtracting the target amount PR from the control amount PO, and performs the current switching function σ by the process described later. The value σ (k) is calculated. The current value σ (k) and the deviation amount e (k) of the switching function σ are output to the control input calculation unit 22.
The control input calculation unit 22 receives the target amount PR, the current value σ (k) of the switching function σ, the deviation amount e (k), and the control amount PO, and calculates the control input amount USM. The control input amount USM is output to the operation amount processing unit 23.
The operation amount processing unit 23 receives the control input amount USM, calculates the operation amount MM, and outputs it to the control target device 13.

  The control target device 13 includes an actuator 25 and a control target member 26. When the control target device 13 is a throttle valve device, the actuator 25 is a motor, and the operation amount MM is a duty in PWM (pulse width modulation) control of the motor. The control target member 26 is a throttle valve that is rotated by the rotation of the motor, and the control amount detector 14 is a throttle opening sensor that detects the opening of the throttle valve. In this case, the control amount PO of the control amount detector 14 is the actual opening of the throttle valve.

Next, processing in the electronic control device 1 will be described below.
First, FIG. 2 shows a flowchart of processing in the sliding mode controller unit 12, that is, processing for calculating the control input amount USM and processing for calculating the operation amount MM.
As shown in step S101, the switching function calculation unit 21 first calculates the current value σ (k) of the switching function σ. The current value σ (k) of the switching function σ is calculated using, for example, an equation of σ (k) = e (k) + η (Δe (k) / Δt). Note that k is an integer added every control cycle (control cycle). For example, when the current control cycle is the kth, the deviation between the control amount PO and the target amount PR of the previous control cycle is e (k−1). Furthermore, η is a gain determined according to the control cycle and control requirements. Δe (k) / Δt is a deviation speed obtained by dividing the difference between the current deviation e and the deviation e before n cycles by time.

  Here, in this embodiment, since there are two state quantity variables, e (k) and Δe (k), for the control target device 13 (control target member 26) used to calculate the switching function σ, sliding is performed. The switching plane in mode control becomes a switching line. Accordingly, the sliding mode controller unit 12 performs control so that the state quantities (e (k), Δe (k)) are constrained to the switching line and the switching function σ is converged to zero.

Subsequently, in step S102, the control input calculation unit 22 calculates an equivalent law input UE. The equivalence law input UE is a state quantity (e (k), Δe (k) of the control target device 13 (control target member 26).
) To the switching function σ = 0.

  Further, in step S103, the control input calculation unit 22 calculates the reaching law input UR. Details of the process for calculating the reaching law input UR will be described later.

  Subsequently, in step S104, the control input calculation unit 22 calculates a nonlinear law input UN. The nonlinear law input UN is an input for eliminating the influence of the error of the controlled object model when the state quantity (e (k), Δe (k)) is converged to the switching function σ = 0.

In step S105, the control input calculation unit 22 calculates the control input amount USM. The control input amount USM is the sum of the equivalent law input UE, the reaching law input UR, and the nonlinear law input UN.
Further, in step S106, the operation amount processing unit 23 calculates the operation amount MM based on the control input amount USM. When the actuator 25 of the control target device 13 is driven, the duty value of the actuator 25 is used as the operation amount MM.

  As a result, the actuator 25 is driven according to the operation amount MM, and the operation of the control target device 13 is controlled. When the control target device 13 is a throttle valve device, the motor, which is the actuator 25, rotates, and the throttle valve, which is the control target member 26 connected via the speed reduction mechanism, rotates. Information on the opening degree of the throttle valve is detected by the control amount detector 14 and input to the sliding mode controller unit 12 as the control amount PO. Thereafter, the above process is repeated for each control cycle to control the control target device 13.

Here, details of the process of calculating the reaching law input UR in step S103 will be described with reference to FIG.
First, in step S201, as preprocessing, the data of the control amount PO before the n-1 control cycle stored in the memory of the sliding mode controller unit 12 is transferred to the control amount PO before the n control cycle. This process is performed on the data of the control amount PO before all control cycles.

In subsequent step S202, the control input calculation unit 22 calculates the current value DPO of the control amount change by subtracting the control amount PO before n control cycles from the current control amount PO.
In step S203, if the current value DPO of the control amount change is equal to or greater than the lower limit value LP1 (first predetermined value), the control input calculation unit 22 determines that the current state is within the normal control range, and step S204. Proceed to Furthermore, if the current value DPO of the control amount change is equal to or smaller than the upper limit value UP1 (second predetermined value) in step S204, the control input calculation unit 22 determines that the current state is within the normal range, and step S205. Proceed to

  Subsequently, in step S205, if the current value σ (k) of the switching function σ is equal to or greater than the lower limit LS1 (third predetermined value), the control input calculation unit 22 determines that the current state is within the normal control range. Determine and proceed to step S206. Furthermore, if the current value σ (k) of the switching function σ is equal to or lower than the upper limit value US1 (fourth predetermined value) in step S206, the control input calculation unit 22 determines that the current state is within the normal control range. Then, the process proceeds to step S207.

  Step S207 is an integration process performed when the change in the control amount is within the normal control range and the switching function σ is within the normal range. In this case, the control input calculation unit 22 sets the first predetermined coefficient C1 (integrated value calculation) to the current value σ (k) of the switching function σ to the value stored in the memory as the previous integrated value SSG (k−1). The value multiplied by the coefficient is added to obtain the current integrated value SSG (k).

Thereafter, the process proceeds to step S211, where the control input calculation unit 22 subtracts the previous value σ (k−1) of the switching function σ from the current value σ (k) of the switching function σ, thereby obtaining the current change amount of the switching function σ. calculate.
In subsequent step S212, the control input calculation unit 22 calculates the proportional term by multiplying the current value σ (k) of the switching function σ by the first gain value (proportional term gain value). Also, the integration term is calculated by multiplying the current integration value SSG (k) by the second gain value (integration term gain value). Furthermore, a differential term is calculated by multiplying the current change amount of the switching function σ calculated in step S211 by a third gain value (differential term gain value). Note that the gains of the proportional term, the integration term, and the differential term may be constant values, or may be determined by searching a map stored in advance in the memory based on, for example, the engine speed and the intake pressure.
In step S213, the control input calculation unit 22 calculates the sum of the proportional term, the integration term, and the derivative term, and further multiplies the sum by the fourth gain value (reaching law calculation gain value) to obtain the reaching law input UR. Calculate.

  Here, when the current value DPO of the control amount change is smaller than the lower limit value LP1 in step S203, it is determined that it is out of the normal control range, and step S208 is performed. Similarly, when the current value DPO of the control amount change is larger than the upper limit value UP1, it is regarded as outside the normal control range, and step S208 is performed. Step S208 is performed when the change in the control amount is outside the normal control range, and is a process for suppressing the integrated component without adding the current value to the previous value, that is, without performing the integration process. Specifically, the control input calculation unit 22 replaces the previous integrated value SSG (k−1) with the current integrated value SSG (k) as it is. Thereafter, the same processing as described above is performed.

  If the current value σ (k) of the switching function σ is smaller than the lower limit value LS1 in step S205, it is determined that it is out of the normal control range, and step S209 is performed. Step S209 is performed when the current value σ (k) of the switching function σ is outside the normal control range, and the current value is added to the previous value, that is, the integration component is suppressed without performing the integration process. It is processing. Specifically, the control input calculation unit 22 calculates the current integrated value SSG (k) by multiplying the previous integrated value SSG (k−1) by the second coefficient C2. The second coefficient C2 is a coefficient that plays a role of gradually returning the current integrated value to zero or returning to the integrated value when converged on the switching plane. For example, a value in a range of 0 ≦ C2 <1 is used. Thereafter, the same processing as described above is performed.

  Furthermore, when the current value σ (k) of the switching function σ is larger than the upper limit value US1 in step S206, it is determined that the current value is outside the normal control range, and step S210 is performed. Step S210 is performed when the current value σ (k) of the switching function σ is outside the normal control range. The current value is added to the previous value, that is, the integrated component is suppressed without performing the integration process. It is processing. Specifically, the control input calculation unit 22 calculates the current integrated value SSG (k) by multiplying the previous integrated value SSG (k−1) by the third coefficient C3. The third coefficient C3 is a coefficient that plays a role of gradually returning the current integrated value to zero or returning to the integrated value when it converges on the switching plane. For example, a value in the range of 0 ≦ C3 <1 is used. Thereafter, the same processing as described above is performed.

Next, with reference to FIG. 4, a specific example of processing of the control device will be described using a timing chart. The horizontal axis indicates the passage of time, and the vertical axis indicates from the top the opening information and the value of the switching function σ when the control target member 26 is a throttle valve.
Prior to time t1, the target amount PR of the throttle valve opening and the control amount PO substantially coincide. That is, at time t1, the state quantities (e (k), Δe (k)) are on the switching plane, and the control amount PO has reached the target amount PR. Accordingly, the deviation e (k) and the deviation speed Δe (k) / Δt are zero, and the current value DPO of the control amount change is also zero.

The target amount PR has increased from time t1 to time t2, but the control target device 13 has not yet followed the change in the target amount PR. For this reason, the control amount PO remains zero. Accordingly, a deviation (= e (k)) occurs between the target amount PR and the control amount PO of the control target device 13, and a deviation change amount Δe (k) also occurs. As a result, the current value σ (k) of the switching function σ is not zero. The current value σ (k) of the switching function σ at this time is a negative value.

  However, at this stage, the current value DPO of the change in the control amount is between the normal control ranges defined by the upper limit value UP1 and the lower limit value LP1. Further, the current value σ (k) of the switching function σ is between the normal control ranges defined by the upper limit value US1 and the lower limit value LS1. In this case, the current integrated value SSG (k) is calculated according to step S207 in FIG. That is, the value obtained by multiplying the current value σ (k) of the switching function σ by the first predetermined coefficient C1 and the previous integrated value SSG (k−1) is the current integrated value SSG (k). In this case, since the previous integrated value SSG (k−1) is a negative value and the current value σ (k) of the switching function σ is also a negative value, the current integrated value SSG (k) is also a negative value and an absolute value. Becomes larger.

  When the target amount PR suddenly increases at time t2, the deviation between the target amount PR and the control amount PO increases. As a result, for example, the current value σ (k) of the switching function σ falls below the lower limit value LS1, and falls outside the normal control range defined by the upper limit value US1 and the lower limit value LS1. In this case, the current integrated value SSG (k) is calculated according to step S209 of FIG. That is, the current integration value SSG (k) is a value obtained by multiplying the previous integration value SSG (k−1) by the second predetermined coefficient C2. Here, the second predetermined coefficient C2 is a coefficient that brings the integrated value back to zero. Therefore, the current integrated value SSG (k) changes such that the increase in absolute value is suppressed and gradually approaches zero as time passes.

  At time t3, when the control amount PO starts to increase behind the rapid increase of the target amount PR, the change amount of the control amount PO also starts to increase. Since the deviation between the target amount PR and the control amount PO decreases as the control amount PO increases, the current value σ (k) of the switching function σ begins to change so as to approach zero.

  Between time t3 and time t4, since the deviation between the target amount PR and the control amount PO is large, the actuator 25 is operated so that the control amount PO quickly catches up with the target amount PR. As a result, the current value DPO of the control amount change greatly increases. At time t4, the current value DPO of the control amount change exceeds the upper limit value UP1, and is outside the normal control range defined by the upper limit value UP1 and the lower limit value LP1. In this case, the current integrated value SSG (k) is calculated according to step S208 in FIG. That is, since the current integration value SSG (k) uses the previous integration value SSG (k−1) as it is, the integration value is kept constant.

  Here, the reason why the previous integrated value SSG (k−1) is used as it is for the current integrated value SSG (k) is to quickly converge the control amount PO to the target amount PR when the transient state returns to the steady state. It is. For example, when the integrated value is set to a smaller value, overshoot can be prevented, but the time to reach the switching plane becomes longer and the convergence speed becomes slower.

  Then, the reaching law input UR is calculated using the current integrated value calculated using the previous value σ (k−1) and the current value σ (k) of the switching function σ, and the control input including the reaching law input UR. When the actuator 25 is driven by this, the target amount PR approaches the control amount PO. As a result, the current value DPO of the control amount change decreases, and at the time t5, the current value DPO of the control amount change falls below the upper limit value UP1 and falls within the normal control range. On the other hand, the current value σ (k) of the switching function σ is below the lower limit LS1, and is outside the normal control range. Therefore, in this time zone, the current integrated value SSG (k) is calculated according to step S209 of FIG. That is, the current integration value SSG (k) is a value obtained by multiplying the previous integration value SSG (k−1) by the second predetermined coefficient C2. As a result, the current integrated value SSG (k) changes such that the increase in absolute value is suppressed and gradually approaches zero as time passes.

  When the current value σ (k) of the switching function σ exceeds the lower limit LS1 and falls within the normal control range at time t6, the current integrated value SSG (k) is calculated according to step S207 in FIG. That is, a value obtained by multiplying the current value σ (k) of the switching function σ by the first predetermined coefficient C1 and added to the previous integrated value SSG (k−1) becomes the current integrated value SSG (k).

  Note that when the target amount PR fluctuates downward and the current value σ (k) of the switching function σ exceeds the upper limit value US1 and falls outside the normal control range, step S210 in FIG. The value SSG (k) is a value obtained by multiplying the previous integrated value SSG (k−1) by the third predetermined coefficient C3. As a result, the current integrated value SSG (k) changes so as to gradually approach zero.

  As described above, in this embodiment, in calculating the integrated component of the reaching law input used by the sliding mode controller unit 12 for calculating the control input amount USM, the current value DPO of the control amount change and the switching function σ If the current value σ (k) is within a predetermined normal control range set for each of the current values σ (k), the current integrated value SSG (k) is calculated by integration processing, and there is a difference between the target amount PR and the control amount PO. As the state continues, the reaching law input UR is increased to easily approach the target amount PR. In contrast, when either the current value DPO of the control amount change or the current value σ (k) of the switching function σ is outside the normal control range, the increase in the absolute value of the integrated component is suppressed. Therefore, it is possible to prevent the integrated component from becoming too large and suppress overshoot. Therefore, the convergence to the target amount can be improved.

  In particular, when the current value σ (k) of the switching function σ is outside the normal control range, the state quantities (e (k), Δe (k)) are far away from the switching plane, and it takes time to reach them. If the state quantity (e (k), Δe (k)) reaches the switching plane, the integration term of the arrival input UR becomes too large and excessively overshoots if the integration process is continued. there is a possibility. Therefore, in this embodiment, under such circumstances, the state quantities (e (k), Δe (k)) are changed to the switching plane by gradually decreasing the absolute value of the current integrated value SSG (k). The total term is not excessive when it reaches. As a result, hunting in the vicinity of the switching plane can be greatly suppressed.

  On the other hand, when the current value DPO of the control amount change is out of the normal control range, the control amount PO has changed greatly. At this stage, the absolute value of the current integrated value SSG (k) is gradually decreased. As a result, it becomes difficult to make the state quantities (e (k), Δe (k)) reach the switching plane quickly. For this reason, holding the previous integrated value SSG (k−1) as the current integrated value SSG (k) prevents the integrated component from becoming too large, while the arrival speed to the switching plane becomes too low. It is prevented.

Note that the present invention can be widely applied without being limited to the embodiments.
For example, the control target device 12 is not limited to a throttle valve device. The actuator 25 may be other than a motor, and the operation amount MM may be a command for operating a device other than the actuator 25.

1 Electronic control device (sliding mode control device)
DESCRIPTION OF SYMBOLS 2 Input detector 11 Target amount calculation part 12 Sliding mode controller part 13 Control object apparatus 14 Control amount detector 21 Switching function calculation part 22 Control input calculation part 23 Operation amount process part 25 Actuator 26 Control object member

Claims (3)

An actuator for operating a member to be controlled;
A control amount detector for detecting a result of operating the member to be controlled by the actuator as a control amount;
A sliding mode controller that calculates an operation amount to be applied to the actuator so that a control amount matches a target amount;
Including
The sliding mode controller unit
A control input is calculated so that the state quantity converges on a switching plane defined by a switching function having the state quantity of the control target member as a variable, and the control input includes the state as an integrated component. The integrated value based on the value of the switching function calculated by substituting the quantity is included,
The integrated value is
When both the change in the control amount and the value of the switching function are within a predetermined range for each, the value corresponding to the value of the current switching function is added to the previously calculated integrated value. Calculate
A sliding mode control apparatus characterized in that when the change in the control amount is outside a predetermined range, the previously calculated integrated value is set as the current integrated value . Wherein when the switching function value is outside the predetermined range, to claim 1, characterized in the coefficients for reducing the integrated value to decrease the value of the current integrated value by multiplying the integrated value previously calculated The sliding mode control device described. An actuator for operating a member to be controlled;
A control amount detector for detecting a result of operating the member to be controlled by the actuator as a control amount;
A sliding mode controller that calculates an operation amount to be applied to the actuator so that a control amount matches a target amount;
Including
The sliding mode controller unit
A control input is calculated so that the state quantity converges on a switching plane defined by a switching function having the state quantity of the control target member as a variable, and the control input includes the state as an integrated component. The integrated value based on the value of the switching function calculated by substituting the quantity is included,
The integrated value is
When both the change in the control amount and the value of the switching function are within a predetermined range for each, the value corresponding to the value of the current switching function is added to the previously calculated integrated value. Calculate
When the value of the switching function is outside a predetermined range, a sliding mode control device that reduces a value of the current integrated value by multiplying a previously calculated integrated value by a coefficient for decreasing the integrated value. .

Images