RU2430398C1 - System of adaptive two-position control - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: procedure is realised by transmitting control effect of following kind to actuating device: if controlled variable crosses line of assignment top down, then duration of effect of adaptive output control signal transmitted to actuating device is determined with interval of time 1·T_u1, where 1 is coefficient of adaptation, while T_u1 is duration of lower half wave of auto-oscillation mode at two-position control; if controlled variable crosses line of assignment bottom-up, then actuating device is turned on after interval m·T_n3 for pulse of feed forward 1·(1-m)·T_u1, where m is coefficient of ratio of nominal load to actual, T_n3 is current value to upper half wave of auto-oscillation mode at two-position control.

EFFECT: establishing control effect of duration reducing duration of half waves of auto-oscillations, which causes reduced amplitude of auto-oscillations and energy saving.

2 cl, 12 dwg

Description

The invention relates to automatic control, and in particular to adaptive systems of on-off automatic control and can be used both in the automation of household objects (electric furnaces, refrigerators), general industrial facilities (muffle furnaces, industrial refrigerators) with on-off control law, and when upgrading existing on-off systems control of technological quantities (temperature, pressure, humidity).

Known on-off control systems built using on-off controllers with fixed positions such as relays, switching is carried out 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. The control signal from the relay output is fed to the input of the actuator, which in turn acts on the control object (in particular, on an adjustable value) (A.A. Kampe-Nemm. Automatic two-position regulation. - M .: Nauka, 1967, p.6 ) The disadvantage of this system is the poor quality of regulation and frequent switching (caused by contact bounce). When using a relay with an ambiguity zone, frequent switching is avoided, but the quality of regulation is degraded.

The purpose of the invention is to eliminate the disadvantages of the on-off control systems associated with the bounce of contacts, and to improve the quality parameters of the controlled process, which reduces the power consumption of the control object.

The technical result of the invention is to propose an original adaptive on-off control system consisting of a controlled variable sensor connected to a relay control winding, to the second winding of which a reference signal is supplied. The relay, comparing these two signals, produces a two-position signal, which is fed to the anti-bounce circuit. A microcontroller is introduced into the system structure, to the input of which there is an output signal of the anti-bounce circuit, in accordance with which a control action is generated according to an algorithm that implements in paragraph 2 an original way to increase control efficiency by adapting to the load. The generated control action from the output of the microcontroller through the output stage is supplied to the actuator acting on the control object.

Figure 1 presents an adaptive system of on-off regulation; figure 2 presents a system of on-off regulation; figure 3 presents the position of the position of the control signal depending on the location of the adjustable parameter relative to the reference line; 4 shows a self-oscillating process in a system with a two-position relay (a), a relay with an ambiguity zone (b), and also a view of the inverse static characteristic of the relay (c) and inverse static characteristic of the relay (d) with hysteresis; figure 5 presents a view of a conditionally approximating function; figure 6 shows a graphical representation of the first - 1 and second - 2 stages of the adaptation algorithm; figure 7 presents an example of slowing down the growth of an adjustable parameter while reducing the control action; on Fig depicts a graphical representation of the seventh - 7 stages of the adaptation algorithm; figure 9 shows a block diagram of a method of adaptive on-off regulation.

The adaptive control system (Fig. 2) consists of a sensor 1 measuring an adjustable value x connected to the coil of relay 2. The relay compares the signal x 'converted by the sensor with the reference signal x ₀ coming from the master 3 (in some cases, the sensor, relay and master represent one device 6). The signal at the output of relay 2 can be in one of two positions of the inverse relay characteristics (Fig. 4, c). The signal y is in the lower position (the relay is open) if the adjustable value is above the reference line (Fig. 3), y is in the upper position, if the adjustable value is under the reference line. This can be written as follows:

The output signal of the relay controller goes to the input of the anti-bounce circuit 4, the output of which is connected to the input of the microcontroller 5. The output of the microcontroller 5 is connected to the output stage 6. The power supply unit 7 provides energy to the programmable set-top box 8 units.

The output stage 6 of the adaptive set-top box 8 is connected to the input of the actuator 9, acting on the control object 10.

In microcontroller 5, the control system algorithm is flashed. For this, the microcontroller structure has a timer that operates both in the duration measurement mode and in the time counting mode, internal memory, for saving the measured values, as well as recording the control algorithm program.

Known methods of on-off regulation based on direct and inverse relay characteristics, where 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, a high level corresponds to finding the controlled variable above the reference line (A.A. Kampe Nemm. Automatic two-position 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 is deteriorated.

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 G05B 11/16. The disadvantage of this method is the low rate of convergence due to the large number of iterations. A higher adaptation speed is achieved by assigning the inactive position to the average value of the effective and inactive values in the event of a controlled parameter rushing out of the adaptation zone патент Patent No. 2158435, IPC ⁷ G05B 11/18. However, in these methods, adaptation occurs 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 (if it is necessary to increase the magnitude of the control action). The patent No. 2129726, 11/54, 11/16 proposes 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 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.

When you turn on the system, an adjustable variable, such as temperature, rises from the initial state, conditionally assumed to be zero, to a certain set value determined by the signal level of the master (Fig. 4, a, the initial section). In this case, the level of the sensor output signal supplied through the feedback circuit to the control winding of the relay configured to operate by a mismatch between the values of the setpoint and sensor signals will increase. 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 a} steady-state self-oscillation mode, which corresponds to T _n11 ≤0.9 · T _n10 (Fig. 6), (i.e., the change in the duration of the lower half-wave is less than 10% compared with the previous self-oscillation). The controller goes into standby mode when the level of control action y changes from low to high. If the start is not the first (the internal memory of the controller P1, P2 is not empty), the algorithm proceeds to step 5.

Stage 2

Otherwise (if the start is the first one), after the control signal у passes from the lower position to the upper timer, it is switched on in the pulse counting mode from an external clock (hereinafter in counter mode), a high voltage level is set at the output (control signal u), shutdown timer-counter occurs at the moment of changing the position of the input signal from upper to lower. The counter timer value T _{u1 is} recorded in the internal memory of the microcontroller P1, the control signal u switches to the lower position. The value of the timer counter is reset and the counter starts again, the counter stops when the position of the relay controller changes from lower to upper, the value of the counter T _{n1 is} recorded in the internal memory P2, the output signal of the set-top box is set to the upper position, the value of the timer-counter is reset.

Stage 3

. Увеличение времени ожидания обусловлено возможным замедлением скорости нарастания регулируемого параметра (фиг.7). Если в течение этого времени произошло изменение фронта входного сигнала с высокого на низкий, то выполнение переходит к началу этапа 4, в ином случае (если изменения не произошло) значение m увеличивается на величину шага Δ, сигнал управления u устанавливается в верхнюю позицию до момента переключения входного сигнала y с верхней на нижнюю позицию. После изменения позиции управляющий сигнал u с приставки переходит в нижнюю позицию до момента изменения позиции входного сигнала y с нижней на верхнюю. Выполнение возвращается к началу этапа 2.From the internal memory P1, the value T _u1 is extracted. The control signal u is set to the upper position. The timer-counter starts in the timer mode for the duration T _u2 = T _u1 · m (where m = 0.8), if the input signal changes from 1 to 0, then during this period the algorithm returns to step 2, i.e. to measure the durations of T _u1 and T _n1 (the cells of the internal memory P1 and P2 are reset to zero). The choice of the coefficient m = 0.8 is due to the real value of the ratio of the nominal load to the maximum. After this time, the control signal is transferred to the lower position, the timer-counter is switched on in timer mode for the time T _u1 · (m ₁ -m), where

. The increase in the waiting time is due to a possible slowdown in the slew rate of the adjustable parameter (Fig. 7). If during this time the front of the input signal changes from high to low, execution proceeds to the beginning of step 4, otherwise (if no change occurs), the value of m increases by the value of step Δ, the control signal u is set to the upper position until switching input signal y from top to bottom. After changing the position, the control signal u from the prefix goes to the lower position until the position of the input signal y changes from lower to upper. Execution returns to the beginning of step 2.

Stage 4

After the input signal y moves to the lower position, the timer-counter is switched on in counter mode. The counter stops when switching the position of the input signal from the lower to the upper, while the event at the output sets the upper position. The value of the counter T _{n2 is} recorded in the internal memory of the controller P3, the counter is reset. Information processing and construction of a conditionally approximating function are taking place. A conditionally approximating function is sought in the form T _n = a · ln (T _u ) + b (1), it is possible to use a linear approximating function in the form T _n = a · (T _u ) + b (2). The choice of the conditionally approximating function is due to the fact that the real static characteristic, which reflects the dependence of the duration of the upper half-wave T _{n of the} controlled variable on the duration of the control pulse T _u , is described in the best way by the logarithmic function. The measured data (T _u1 , T _n1 , T _n2 , T _u2 ) are extracted from the internal memory of the controller P1, P2, P3. Coefficients a and b are found from systems of equations (1) and (2) by formulas (9) or (10).

After calculating the coefficients a and b, the value of T _{u3 is} calculated in some ε-neighborhood of the optimum point T _u0 (ε = k · T _n1 , where k is the adaptation quality factor 0≤n≤1). The nominal operating mode at the optimum point implies the supply of a control signal u of such duration T _u0 at which T _n = 0. In reality, the optimum is difficult to reach because the optimum point is floating due to external influences. Therefore, the desire for an optimum point in conditions of a minimum of information can lead to the process coming out of self-oscillating stability. After that, according to formula 11, the value of the adaptation coefficient l is calculated. Execution proceeds to step 5.

Stage 5

After changing the position of the input signal y from the lower to the upper, the control signal u is set to the upper position, the timer counter is reset and starts in timer mode for a time l · T _u1 , after which a program interrupt from the timer is performed, the position of the control signal is transferred to the lower , the timer value is reset, the timer starts again for the time (m ₁ -l) · T _u1 . During this time, the microcontroller polls the input state and, if the position of the input signal y changes from the upper to the lower timer, it is reset to zero if the internal memory cell P4 is empty, execution proceeds to step 6, otherwise, to step 7. If the change has not occurred, the adaptation coefficient increases l: = l + 2Δ, the timer value is reset.

Execution returns to the beginning of step 5.

Stage 6

After changing the position of the input signal y from upper to lower, the timer-counter is switched on in counter mode, stopping occurs when the edge of the input signal y changes from 0 to 1. The control signal is set to the upper position. The value of T _n1 is extracted from the internal memory cell P2. The current value of the timer-counter T _{n3 is} compared with k · T _n1 (where k is the adaptation quality factor). If T _n3 > k · T _n1 and l was not reconfigured at the previous stage, then the value of l decreases by the value of step l: = l-Δ, execution returns to step 5. If T _n3 > k · T _n1 , but at the previous stage the l was reconfigured, then execution returns to step 5. If T _n3 ≤k · T _n3 and at the previous stage the l did not reset, then the current counter timer value is stored in P4, and execution returns to step 5. If T _n3 ≤k · T _n1 , but at the previous stage there was a reconfiguration of l, then execution returns to step 5.

Stage 7

During the execution of this stage, the position of the position of the input signal y is continuously interrogated, when changing from the lower to the upper, the cell of the internal memory P4 is cleared and the process proceeds to step 5. The value T _n3 is extracted from the internal cell of the memory P4. The timer counter is switched on in timer mode for a time m · T _n3 . After this time, the position of the output stage position is moved to the upper position. The value of T _u1 is extracted from the internal memory cell P1. The timer is zeroed and started in the time counting mode l · (lm) · T _u1 (Fig. 8), after which the control action is transferred to the lower position, the timer stops and is reset. The execution proceeds to step 5. A graphical explanation of step 7 in (Fig. 8).

When the control object 10 is stopped, the execution of the algorithm proceeds to the initial stage.

The technical result achieved is to find a control action of such a duration that reduces the half-wave length of self-oscillations, which leads to a decrease in the amplitude of self-oscillations and energy saving.

Claims (2)

1. Microprocessor on-off control system containing a serially connected master, a relay element with two control windings, the first of which is connected to the output of the master, an adaptive controller, actuator, control object and a sensor connected by its output to the second winding of the relay element, characterized in that an intelligent controller has been introduced into the system structure, all of whose elements are connected by power to a power supply unit, consisting of an anti-bounce circuit, the input of which I is simultaneously the input of the adaptive controller connected to the output of the relay element, and the output with the input of the microcontroller connected by its output to the input of the output stage, which is a power amplifier, the output of which is simultaneously the output of the adaptive controller associated with the actuator. 2. The method of automatic on-off regulation, based on adapting the duration of the control action with a constant step Δ, to the current load of the control object using on-off signals at the output and at the input of the adaptive controller, characterized in that it is introduced using a microcontroller included in the structure of the adaptive controller, the conditionally approximating function forces the adaptation process, allowing us to calculate the value of the pulse duration T _u3 at the initial stage of regulation in some ε neighborhood of the optimum point T _u0 , and accordingly start adaptation from this value, and the adaptation of the control action lasts until the current value of the upper half-wave becomes less than the initial half-wave value multiplied by the adaptation quality factor k, after which the control logic of the actuator using the output of the controller is as follows: if the adjustable variable crosses the reference line from top to bottom, then the duration of exposure of the adapted control output signal I, applied to the actuator, is determined by the time interval l · T _ul , where l is the adaptation coefficient, and T _ul is the duration of the lower half-wave of the self-oscillating mode with on-off regulation, if the intersection of the task line of the adjustable variable occurs from the bottom up, then the actuator turns on after the interval m · T _n3 per anticipation pulse l · (lm) · T _ul , where m is the ratio of the nominal load to the real one, T _nl is the duration of the upper half-wave of the self-oscillating mode with a two-position walking

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