RU2498386C1 - Method for adaptive two-position control - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: disclosed is a method for automatic two-position control of oscillatory processes, based on adaptation of duration of the control action with a varying step under the current load of the control object using a two-position signal at the input and output of the controller. Step variation is carried out iteratively depending on the rate of convergence of the process and the approach of the duration of the upper half-wave T_n2 to the value of the expression (1+T_n1/T_u1)·k·T_n1, where T_n1, T_U1 denote the duration of the upper and lower half-waves of the process in steady state conditions during two-position control, k is a coefficient which characterises the required quality of adaptation; at the next step, adaptation is performed iteratively in steps with step value 1 and quality criterion T_n2≤k·T_n1. The control action is then an adapted output signal with duration (1-0.01·k·ℓ)·T_u2, where T_u2 is the duration of the control action obtained at the step for adaptation with a variable step, ℓ is a coefficient obtained at the step for adaptation with a constant step.

EFFECT: reduced self-oscillation amplitude and power saving.

4 dwg

Description

The invention relates to automatic control, namely to adaptive on-off control, and can be used both for controlling household objects (electric furnaces, refrigerators), and general industrial facilities (muffle furnaces, industrial refrigerators).

Known methods of on-off regulation based on a direct relay characteristic, switching is performed when the controlled variable passes through the reference line, a low signal level corresponds to finding the controlled variable under the reference line, and a high level corresponds to finding the controlled variable above the reference line (A.A. Kampe-Nemm. Automatic on-off regulation. - M .: Nauka, 1967, p. 7). The disadvantage of this method is the low quality of regulation. When using the relay control law with an ambiguity zone, frequent switching is avoided, but the quality of regulation deteriorates.

Also known is a method based on the run-out of an adjustable value for a given adaptation zone. Depending on the coasting direction, the value of the inactive position of the controller is changed in the direction of the current position of the controller according to US Pat. No. 2144690 IPC ⁷ , G05В 11/16. The disadvantage of this method is the low rate of convergence due to the large number of iterations. A higher adaptation rate is achieved by assigning the inactive position to the average value of the effective and inactive value in the case of a run-out of the adjustable parameter outside the adaptation zone, US Pat. No. 2158435 IPC ⁷ , G05В 11/18. However, in these methods, adaptation takes place in only one direction (the magnitude of the control action can only decrease), and the method does not offer the possibility of reconfiguring the value of the control action in the event of a change in the load of the object. In US Pat. No. 2129726 IPC ⁷ , G05В 11/54, 11/16 proposed the introduction of a rehabilitation zone. In the case of a run-out of an adjustable value over the readaptation zone of the current position, its extreme value is assigned and adaptation starts anew. In all of the above methods, an analog signal is used at the input of the controller, while a two-position signal can be sufficient for control. Also, a positional control signal is used at the controller output, while the use of a two-position signal can significantly simplify the design and principle of operation of regulators based on adapting the control action to the current load of the object.

The purpose of the invention is the acceleration of the adaptation process and the improvement of quality parameters of the regulated process, leading to a reduction in energy consumption of the control object.

The technical result consists in proposing a new method of adaptive on-off regulation, leading to a decrease in the amplitude of self-oscillations and energy saving.

This goal is achieved due to the fact that in the proposed method of automatic on-off regulation of oscillatory processes, based on adapting the duration of the control action with a varying step to the current load of the control object using a two-position signal at the input and output of the controller, the step is changed iteratively depending on the speed convergence of the process and approximation of the duration of the upper half-wave T _n2 to the value of the expression (1 + T _n1 / T _u1 ) · k · T _n1 , where T _n1 , T _u1 is the duration b the upper and lower half-waves of the process in the steady state with two-position control, k is the coefficient characterizing the required quality of adaptation, at the next stage the adaptation is iteratively step by step with a value of step 1, with the quality criterion T _n2 ≤k · T _n1 , after which the control action represents an adapted output signal of duration (1-0.01 · k · l) · T _u2 , where T _u2 is the duration of the control action obtained at the adaptation stage with a variable step; l is the coefficient obtained at the stage of adaptation with a constant step.

When the system is turned on, the controlled variable x ', for example, the temperature, changes from its initial state to a certain set value x ₀ , while the input of the regulator receives a high level of the input signal y (logical unit "1") when the controlled variable x' is below the set value . The input of the controller receives a low level of the input signal y (logical zero "0") when the adjustable variable x 'is above the specified value:

Such a control law is called an inverse relay characteristic (Fig. 1). In the unsteady mode, the value of the input signal x 'is relayed to the output, i.e. u = x '. With this regulation, the dynamics of the process is a self-oscillating mode, and the amplitude of the oscillations will decay to a certain steady-state value.

The proposed method for suppressing self-oscillations consists in the implementation of the following steps.

Stage 1. After the adjustable parameter _{reaches the} steady-state self-oscillation mode, which corresponds to T _n11 ≤ (1-k) -T _n10 (where k <1 is the coefficient characterizing the required quality of adaptation; T _n11 , T _n10 is the duration of the upper half-wave of the current and previous oscillations (Fig. 2)). It waits to change the input signal level y from low to high. After the transition of the input signal y from the state "0" to "1" at the output (control signal u), a high level is set and the calculation of the duration of the input signal y to the state "1" - T _u1 begins. When the level of the input signal y changes from high to low, which happens when the sign of the half-wave x 'changes, the counting of T _u1 stops and the duration of the input signal y in the state “0” - T _{n1 is counted} , which stops when the level of the input signal changes from low on high.

Stage 2. After the transition of the input signal y from the state “0” to “1”, the output signal u is set to the upper position for the duration T _u2 (where the initial value T _u2 = (1-k) · T _u1 ), if during this time if the input signal is low, then the execution of the algorithm returns to measuring the durations T _u1 and T _n1 . After the expiration of T _u2, the control signal u moves to the lower position and remains in it for the interval (1 + 0.1-T _n1 / T _u1 ) · (T _n1 -T _u2 ) (the increase in the waiting time is due to a possible slowdown in the slew rate of the adjustable parameter (Fig .3)). If during this time the front of the input signal does not change from high to low, then the value of T _u2 : = (1 + k) · T _u2 , and execution proceeds to step 3, otherwise, execution proceeds to step 4.

Step 3. The output signal u is set to the upper position for the time n · T _{u1 ·} k (where initially n = 2), after which the output signal u is set to the lower position for the time (1 + 0.1 · T _n1 / Т _u1 ) · ( T _u1 -T _u2 ) / n. If the input signal y during the iteration has changed from “1” to “0”, then m: = (l + n · k) execution proceeds to step 2. Otherwise, n: = n · 2 and execution returns to the beginning of step 3 .

Stage 4. After the transition of the input signal from state “1” to “0”, T _n is measured — the time the input signal was at the lower position, after which the coefficient m is calculated: = T _n2 / T _n1 (if m> 1, then execution proceeds to step 2, and m: = (1-k). Then, T _{n is} compared with (1 + T _n1 / T _u1 ) · k · T _n1 . If T _n ≤ (1 + T _n1 / T _u1 ) · K · T _n1 , then execution proceeds to step 5, otherwise T _u2 : = (1 + k) · T _u2 and execution returns to step 2.

Step 5. After the transition of the input signal y from the state “0” to “1”, the output signal u is transferred to the upper position for the duration T _u3 : = (1-0.01 · k · l) · T _u3 (where the initial value is T _u3 = T _u2 , i.e., the duration of the pulse received during the setup mode, and l is the number of the current iteration, initially equal to 1). After the expiration of the time interval T _{u3, the} output signal u is shifted to the lower position by (1 + 0.1 · T _n1 / T _u1 ) · (T _u1 -T _u3 ) if during this time the position of the input signal y changes from “1” to “ 0 ”does not occur, then execution proceeds to step 3. Otherwise, T _n3 is measured - the time during which y was in the lower position and compared with k · T _n1 . If T _n3 > k · T _n1 , then l: = l + 1, otherwise l: = l. Execution returns to the beginning of step 5.

A graphical description of the method is presented in the form of a flow chart in Fig. 4.

Claims (1)

A method of automatic on-off regulation of oscillatory processes, based on adapting the duration of the control action with a varying step to the current load of the control object using a two-position signal at the input and output of the controller, characterized in that the step is iterated depending on the rate of convergence of the process and the approximation of the duration of the upper half-waves T _n2 to the value of the expression (1 + T _n1 / T _u1 ) · k · T _n1 , where T _n1 , T _u1 - the duration of the upper and lower half-waves of the process the new mode with on-off regulation; k is a coefficient characterizing the required quality of adaptation; at the next stage, adaptation occurs iteratively step by step with a value of step 1, with a quality criterion T _n2 ≤k · T _n1 , after which the control action is an adapted output signal with a duration of (1-0.01 · k · l ) · T _u2 , where T _u2 is the duration of the control action obtained at the adaptation stage with a variable step; l is the coefficient obtained at the stage of adaptation with a constant step.

Images