Adaptive system for controlling object with variable transporting delay

FIELD: automatics.

SUBSTANCE: system has set-point device, first adder, adjusting means, first object model, first delay element, second object model, adjustment block, processed product movement indicator, first quantizer, compensation adjusting means, second adder, multiplier, extrapolator, comparison element, second quantizer, second delay element, first, second, third and fourth keys.

EFFECT: higher speed of operation, higher efficiency, broader functional capabilities.

5 dwg

The invention relates to automation, in particular to adaptive automatic control systems, designed to control objects with variable transport delay in terms of perturbations of a random nature and can be used on production lines, textile, light and chemical industries.

A device management object with delay control (Smith) [1], which includes a standard controller, model of the object without delay, delay element, the first, second and third adders.

In this system the high performance is achieved by predicting the reaction of the object on the control action using the model without delay. Thus, the outputs of the model is input to the controller, typically the model.

The disadvantage of such systems is a significant deterioration in the accuracy and performance even with small variations in the parameters of control object, first of all lag. In addition, the performance of this system in the course of the disturbance is limited to the value of 1.5-2 delay interval.

Also known control system of drying and tentering machine (SSM) [2], representing the object with a transport delay. This system includes sensors parameters of the fabric (width, density, wet the STI), direct channel management, channel feedback proportional-integral (PI) controller and subsystem control the temperature in the drying chamber of the machine.

This high performance when mining disturbances is achieved through a direct channel to the compensation controller, and the accuracy of stabilization due to the feedback channel.

However, this system requires long-term settings when changing the settings of the control object, for example, by changing the code of the processed tissue. In addition, the presence of channel feedback PI regulator leads to a transition with duration of 5-6 intervals lag when turning on the system.

The closest technical solution is an adaptive control system for objects with delay [3], which contains the generator, the adder, the regulator and the object, as well as two models of the object (two predictor), delay element and tuner models.

This high performance is achieved through the application of the model object without delay, the signal which is fed to the input of the regulator, and adaptation to change parameters of an object is provided by the tuner.

The disadvantage of this system is to limit the performance when developing the perturbation size 1.5-2 delay interval and hudsonia quality regulation to the extent that the delay object.

The technical result of the invention is to improve the performance of the system in the course of disturbances, ensuring change adaptation lag and transmission ratios of the object, the reduction in the duration of transients when switching on the system.

To achieve a technical result in a system consisting of a knob, the first adder, the controller, the first model object and the first delay elements connected in series, the second model of the object block settings and object with a variable delay, also includes a displacement sensor of the processed product, the first quantizer, a compensation controller, the second adder, multiplier, extrapolator, the element of comparison, the second quantizer, the second delay element, the first, second, third and fourth keys.

At the first input of the first quantizer signal perturbations, and the second input is connected to the output of the displacement transducer, the output of the compensation controller is connected to the first input of the second adder, the output of which is connected to the first input of the multiplier, the output of extrapolator connected to the first input of the control object, to the second input of which affects the above signal perturbations. The first input of the tuner is connected to the output of the first quantizer, a second input from the output of the second quanta of the body, and a third input from the output of the displacement sensor, the first output of the tuner is connected to the second input of the multiplier, the first input of the second quantizer coupled to the output of the control object, the second input with the output of the displacement sensor. The input of the comparison element is connected with the second input of the tuner and output to the control inputs of the first, second, third and fourth keys. The output of the second quantizer through the fourth key is connected with the second input of the first adder, the third entrance through which the third key is connected to the output of the second delay element, a fourth input connected to the output of the first delay element, the fifth input - output of the first model of the object, the second input of the second adder through the first key is connected to the generator, a third input via the second key is connected to the controller output, the input of the second model object connected to the controller output and the output with the input of the second delay element.

Comparative analysis of the prototype showed that the proposed control system is characterized by the presence of the displacement transducer, the first and second quantizers, the compensation controller, the second adder, multiplier, extrapolator, comparison element, the second delay element, the first, second, third and fourth key elements and relationships between them, namely the following.

With the United sequentially first quantizer, the compensation controller, the second adder, multiplier and extrapolator form a straight channel compensation of disturbances. The introduction of such a channel in the control system with delay allows you to achieve maximum performance when mining disturbing influences.

Combined controllers in control systems with delay is known technical solution. However, in this case, the introduction of new elements and relationships between them provides the adaptation of the system to changes in the parameters of the object, as well as the sustainability of the processes of learning.

The multiplier, a second input connected to the first output of the tuner, tune the compensation controller when changing the transmission factor of the object. The criterion for this is the transfer coefficient of the system by the transmission channel disturbances, which in the configuration process is reduced to zero.

The application of the first, second, third and fourth keys that control block comparison, provides off regulator Smith from the object in edit mode, and connection instead of the second model with the second delay element. This solution makes it possible to ensure the stability of the configuration process, and also to eliminate transients when switching the system to the operating mode.

The use of sensor re is edenia and quantizers with variable period of quantization allows to adapt the system to changes in the lag time of the control object. The time lag of the first and second delay elements is set in relative units - periods quantization.

Therefore, the observed differences between the proposed device from analogs and prototypes are essential.

Structural diagram of the adaptive control system (figure 1) includes a first quantizer 1, the compensation controller 2, the second adder 3, a multiplier 4, extrapolator 5, the control object 6, the displacement sensor 7, the tuner 8, block 9 comparison, the second quantizer 10, unit 11, the first key 12, the second key 13, the first adder 14, a controller 15, the first model of the object 16 and the first delay element 17, the second model of the object 18 and the second delay element 19, the third key 20 and the fourth key 21.

The disturbance arrives at the first input of the first quantizer 1, the second input (control input) which is connected to the output of the displacement sensor 7. The digital signal of the first quantizer passes through connected in series compensation knob 2, the second adder 3, a multiplier 4 and extrapolator 5. The output of the compensation controller 2 is connected to the first input of the second adder 3, the second input is through the first (normally-closed) key 12 is connected with the output of the generator 11, and the third input through the second (normally-open) switch 13 is connected to the output of the controller 15. The signal is output from the second adder 3 passes through the multiplier 4 and extrapolator 5, the output of which is connected to the input of the object 6. The output of the object 6 is connected to the first input of the second quantizer 10, to the second input of which receives the signal of the displacement sensor 7.

The output of generator 11 is connected to the first input of the first adder 14, which are sequentially connected to the controller 15, the first model of the object 16 and the first delay element 17. The output of the controller 15 is connected also to the input of the second model of the object 18, the output of which is connected to the input of the second delay element 19. The second input of the first adder 14 through the fourth (normally-open) switch 21 is connected to the output of the second quantizer 10, the third input through the third (normally closed) key 20 with the output of the second delay element 19, the fourth input - output of the first delay element 17, the fifth input - output of the first model object 16.

The first and second inputs of the tuner 8 is connected to the outputs of the first (1) and second (10) quantizers, respectively, a third input connected to the output of the displacement sensor 7, the first output unit 8 is connected with the second input of the multiplier 4, the second output from the input unit of comparison 9, the output of which is connected to the control inputs of the first (12), second (13), third (20) and fourth (21) keys.

The control object 6 consists of the link without delay with transfer function H₀₁(s) and link transport delay from transmit the offered function H ₀₂(s)connected in series. At the first input of the object 6 is fed the control action u(s), and to the second input signal perturbation x(s):

where y(s) is the output signal of the object;₁and K₂- transfer coefficients; T₁- time constant; τ the time lag, s-argument of Laplace.

The transfer function of the compensation controller 2 inverse transfer function of the control object H₀₁(s):

H_KR(z)=I/H₀₁(z); H₀₁(z)=Z{H₀₁(s)H_e(s)}, (2)

where Z is the symbol of the conventional z - transform (tables); H_e(s)=(1-s^-sTo)/s - transfer function of extrapolator; T_about- period of the quantization of time. Taking into account expression (1) we get

H_KR(z)=1-dz^-1, (3)

where d=T/T_about- time constant.

Unit 8 provides the setting of the gain compensation controller_R[i] in accordance with recurrent expression

where h is the factor that sets the tempo settings;- evaluation of the coefficient of transmission system disturbance ΔK=1-K_RTo_o; i - period number of quantization. Evaluationare calculated using the least squares method (OLS)

where x[i, j] - disturbing impact of the object; y[i, j] is the output signal of the object; j is the sample number, n is the number of samples within a period of quantization; m=int(τ/T_othe relative magnitude of the lag. The value of K_R[i] is supplied to the first output unit 8, and the value of- on the second output block.

In configuration mode, the system operates as follows. The estimated coefficient of the transmission system to channel perturbationsis formed on the second output of the tuner 8 and is compared with the block 9 with significance level δK. providedunit 9 closes the first (12) and third (20) and opens the second (13) and fourth (21) keys. When the control object 6 is excluded from the feedback circuit and instead turns on the second model 18 and the second delay element 19. On the object affected by the signal compensation knob 2 and knob 11, the joint second adder 3. Setting the compensation controller is block 8, at each step is computed OLS - estimated coefficientand the correction value K_R[i]. As soon as the estimate becomes insignificant, unit 9 switches the system structure and translates it into a work mode.

In operation, whenthe block 9 is closed by the second (13) and fourth (21) and disconnects the first (12) and third (20) is Lucy. Thus instead of the second model 18 and the second delay element 19 in the feedback circuit includes the control object 6. The result is a combined control system with forward and reverse channels. Direct channel system provides effective compensation for disturbance, and the feedback channel is the reduction to zero static error. The application of the second model of the object (18) and the second delay element (19) allows to eliminate the process of transition when switching the system structure.

When you change the delay (speed transportation varies the repetition period of pulses of the sensor 7, which control the quantizers 1 and 10. Thus, by changing the period of the quantization is carried out setting the digital system on the actual amount of delay of the control object.

The simulation results of the adaptive management system object with delay in terms of the perturbations is presented on figure 2, figure 3, figure 4 and figure 5. The disturbance at the input of the control object (figure 2) is a random process of recovery, with a superimposed Gaussian random process.

A graph of the gain compensation controller_Ris shown in figure 4, and a graph of the coefficient of transmission system channel disturbances ΔK - 5. Analysis of g is apikov shows that transition in the path of adaptation is completed within a time interval equal to 4÷5 intervals lag, overshoot does not exceed 10%.

The transient response of adaptive control systems object with delay is shown in figure 3. The end of the adaptation process is marked by the dash-dotted line, and the connection controller Smith does not cause the system transition process. Configured system virtually eliminates the influence of the disturbances on the controlled variable. This is due to the high speed forward channel compensation adjustment time which is equal to the period of the quantization of T_o. Change the set value of the density at time t=200 illustrates the dynamic properties of the feedback loop system. The transition process in the circuit is completed at time intervals equal to 1.5 lag and overshoot does not exceed 1÷2%.

Thus, the proposed system provides high accuracy and speed as in compensation the perturbation, and when developing transition effects. In addition, the system adapts to changes in the coefficients of transmission and time delay of the control object.

Sources of information

1. The górecki X. Analysis and synthesis of control systems with delay. - M.: Mashinostroenie, 1974. - 328 S.

3. A.S. 968788 the USSR, MKI G 05 In 13/02. Adaptive control system for objects with variable delay. / Out etc. // Opening. Of the invention. 1982 - No. 39.

Adaptive management system object with a variable transport delay containing unit, a first adder, the controller, the first model of the object, the first delay element connected in series, the tuner, the second model of the object and a control object with a variable delay, which affects the perturbation, characterized in that the system further include a first quantizer, a compensation controller, the second adder, multiplier and extrapolator series-connected, the pulse sensor move the product to be processed, the block comparison, the second quantizer, the second delay element, the first, second, third and fourth keys, and on the first the input of the first quantizer signal perturbations, and the second input is connected to the output of the pulse sensor move the product to be processed, the output of the compensation controller is connected to the first input of the second adder, the output of which is connected to the first input of the multiplier, the output is extrapolator connected to the input of the control object, the first input of the tuner is connected to the output of the first quantizer, a second input from the output of the second quantizer, and a third input - output pulse displacement sensor of the processed product, the first output of the tuner is connected to the second input of the multiplier, the first input of the second quantizer coupled to the output of the control object, the second input with the output of the displacement transducer, and the output through the fourth key is connected with the second input of the first adder, the third entrance through which the third key is connected to the output of the second delay element, a fourth input connected to the output of the first delay element, the fifth input - output first the model of the object, the second input of the second adder through the first key is connected to the generator, a third input via the second key is connected to the controller output, the input of the second model object connected to the controller output and the output with the input of the second delay element, the input unit of comparison is connected with the second output of the tuner and output to the control inputs of the first, second, third and fourth keys.