A Fuzzy Semi-Closed Loop-Based Oil Elastic-Plastic Control Algorithm

Abstract

The present invention belongs to the technical field of oil processing, and specifically relates to an oil elastic-plastic control algorithm based on a fuzzy semi-closed loop. The oil elastic-plastic control is converted into the oil water content control, and the water content error and the water content error change rate are comprehensively considered. The fuzzy control rule is used to control the speed value of the servo motor of the homogenizer softener, which can improve the control accuracy of the oil softening device on the oil elastic-plasticity, and has good real-time performance and robustness; a relationship table between the oil elastic-plasticity and the water content is established, and combined with the human-computer interaction interface of the control system, the oil elastic-plastic index can be quickly converted into the corresponding oil water content index; a weighted recursive average filtering method is proposed to filter the water content feedback value of the oil at the outlet of the homogenizer softener, which can improve the stability of the fuzzy control.

Description

Technical Field

[0001] The invention belongs to the technical field of oil processing, and in particular relates to an oil elastic-plastic control algorithm based on a fuzzy semi-closed loop. Background Art

[0002] my country is a major producer of edible vegetable oil, and its consumption of vegetable oil ranks first in the world all year round. The main technologies for obtaining vegetable oil from oilseeds include pressing, extraction, water substitution, etc., but the existing industrial oil production technology is still mainly based on pressing. Pressing refers to the use of mechanical external force to squeeze oil out of oil. If the temperature and moisture of the oil do not meet the requirements of the oil press, it is easy to cause the cake to not form, the oil is not completely squeezed out, and the oil yield is reduced. The oil softening devices used on the market are generally intermittently operated, and the elastic and plastic properties of the oil cannot be directly obtained by means of sensors, resulting in low control accuracy and failure to meet the quality requirements of oil supply. Summary of the invention

[0003] The technical problem to be solved by the present invention is: in view of the deficiencies of the prior art, a fuzzy semi-closed loop based oil elastic-plastic control algorithm is provided, which can improve the control accuracy of the oil softening device on the oil elastic-plasticity, and has good real-time performance and robustness.

[0004] The technical solution adopted by the present invention to solve the above technical problems is:

[0005] An oil elastic-plastic control algorithm based on a fuzzy semi-closed loop is used to control an oil continuous softening device, and specifically includes the following steps:

[0006] S1, the user inputs the elastic-plastic index of oil through the human-computer interaction interface;

[0007] S2, the control system obtains the oil water content index corresponding to the oil elastic-plastic index by searching the oil elastic-plastic and water content relationship table;

[0008] S3, the control system uses a weighted recursive average filtering method to filter the moisture content sensor measurement value at the outlet of the homogenizer softener to obtain a filtered moisture content value;

[0009] S4, the control system uses the material moisture content index as input, the filtered moisture content value as feedback, and adopts a fuzzy semi-closed loop control algorithm to adjust the speed of the servo motor of the homogenizer softener in real time, so that the measurement value of the moisture content sensor at the outlet of the homogenizer softener is close to the oil moisture content index.

[0010] Furthermore, the relationship table between the elastic-plastic properties of oil and its water content is obtained through laboratory measurements.

[0011] Furthermore, the weighted recursive average filtering method is specifically as follows: the moisture sensor measurement value is collected once every 0.1s, the 10 consecutive sampling values ​​are set as a queue, each new value collected is put at the end of the queue, and the value at the head of the queue is removed, and finally the weighted average value of the 10 values ​​in the queue is calculated to obtain the filtered moisture content value.

[0012] Furthermore, the weighted array for calculating the weighted average value is coe

[10] =[15, 12, 9, 7, 6, 5, 4, 3, 2, 1], and the specific formula for the moisture content value after filtering is:

[0013] MC fdb =(15*MC fdb1 +12MC fdb2 +.....+1MC fdb10 ) / (15+12+.....+1)

[0014] In the formula, MC fdb is the moisture content value after filtering, MC fdb1 is the moisture content sensor measurement value collected this time, MC fdb2 The moisture content sensor measurement value collected 0.1s ago...MC fdb10 It is the water content sensor measurement value collected 0.9s ago.

[0015] Furthermore, the oil elastic-plastic control algorithm based on fuzzy semi-closed loop is specifically as follows:

[0016] Every 10 seconds, the moisture content error MC is obtained according to the filtered moisture content value. err and moisture content error change rate MC ec_err , and obtain the speed output value O according to the fuzzy control rule, the speed output value O is multiplied by the correction factor K P Get the speed output correction value V offset , through the speed output correction value V offset The speed value of the servo motor of the homogenizer and softener is adjusted as the target value.

[0017] Furthermore, the moisture content error MC err =MC ref -MC fdb , where MC ref is the index of oil water content, MC fdb is the moisture content value after this filtering;

[0018] The moisture content error change rate MC ec_err =MC err -MC err_temp , where MC err_tempis the moisture content error of the last time.

[0019] Furthermore, the fuzzy control rules are specifically as follows:

[0020] O=O temp ×(K E ×MC err +K C ×MC ec_err )

[0021] In the formula, O temp is the last speed output value, K E is the moisture content error quantification factor, K C is the quantitative factor of the moisture content error change rate.

[0022] Furthermore, the moisture content error quantification factor K E =n / X E , where n is the fuzzy set domain of moisture content error, X E is the basic domain of moisture content error; the moisture content error change rate quantification factor K C =m / X C , where m is the fuzzy set domain of the moisture content error change rate, X C It is the basic domain of moisture content error change rate.

[0023] Compared with the prior art, the present invention has the following main advantages:

[0024] 1. The oil elastic-plastic control is converted into oil moisture content control, and the moisture content error and the moisture content error change rate are comprehensively considered. The fuzzy control rule is used to control the speed value of the servo motor of the homogenizer softener, which can improve the control accuracy of the oil softening device on the oil elastic-plastic property, and has good real-time performance and robustness.

[0025] 2. A relationship table between oil elasticity and plasticity and water content has been established. Combined with the human-computer interaction interface of the control system, the oil elasticity and plasticity index can be quickly converted into the corresponding oil water content index;

[0026] 3. A weighted recursive average filtering method is proposed to filter the moisture content feedback value of the oil at the outlet of the homogenizer softener, which can improve the stability of fuzzy control. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a flow chart of the control algorithm of the present invention;

[0028] Figure 2 is the moisture content error MC in the embodiment of the present invention err The membership function of each fuzzy subset;

[0029] Figure 3is the moisture content error change rate MC in the embodiment of the present invention ec_err The membership function of each fuzzy subset;

[0030] Figure 4 is the membership function of each fuzzy subset of the speed output value O in the embodiment of the present invention;

[0031] Figure 5 It is a schematic diagram of the oil continuous softening device of the present invention.

[0032] In the figure: 1. Receiving trough after frying seeds; 2. Oil elevator; 3. Homogenizer and softener; 4. Oil storage tank after softening; 5. Discharge port; 6. Steam generator; 7. Steam regulating valve; 8. Moisture content sensor; 9. Servo motor. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0034] It should be pointed out that, according to the needs of implementation, the various steps / components described in this application can be split into more steps / components, and two or more steps / components or partial operations of steps / components can be combined into new steps / components to achieve the purpose of the present invention.

[0035] 1. A Fuzzy Semi-Closed Loop-Based Oil Elastic-Plastic Control Algorithm

[0036] like Figure 1 As shown, the embodiment of the present application provides an oil elastic-plastic control algorithm based on a fuzzy semi-closed loop, which specifically includes the following steps:

[0037] S1, the user inputs the elastic-plastic index of oil through the human-computer interaction interface;

[0038] S2, the control system (in this example, a PLC control system) obtains the oil water content index corresponding to the oil elastic-plastic index by searching the oil elastic-plastic index and water content relationship table;

[0039] Among them, since the elasticity and plasticity of oil cannot be obtained through real-time on-site collection, a lookup table of the elasticity and plasticity and moisture content of different oils is established in the laboratory. The PLC obtains the moisture content of the oil corresponding to the specified elasticity and plasticity by searching the relevant table.

[0040] S3, the control system performs filtering processing on the moisture content sensor measurement value at the outlet of the homogenizer softener according to the sampling frequency of 100ms and adopts the weighted recursive average filtering method to obtain the filtered moisture content value;

[0041] Among them, since the collected oil moisture content fluctuates within a range, directly using the collected feedback value will cause the fuzzy controller to adjust too frequently and violently. It cannot truly reflect the trend of the oil moisture content. Therefore, the oil moisture content must be properly filtered.

[0042] The weighted recursive average filtering method is specifically as follows: the moisture sensor measurement value is collected once every 0.1s, the 10 consecutive sample values ​​are set as a queue, each new value collected is put at the end of the queue, and the value at the head of the queue is removed, and finally the weighted average value of the 10 values ​​in the queue is calculated to obtain the filtered moisture content value.

[0043] In this embodiment:

[0044] The weighted array for calculating the weighted average value is coe

[10] =[15, 12, 9, 7, 6, 5, 4, 3, 2, 1], and the specific formula for the moisture content value after filtering is:

[0045] MC fdb =(15*MC fdb1 +12MC fdb2 +.....+1MC fdb10 ) / (15+12+.....+1)

[0046] In the formula, MC fdb is the moisture content value after filtering, MC fdb1 is the moisture content sensor measurement value collected this time, MC fdb2 The moisture content sensor measurement value collected 0.1s ago...MC fdb10 It is the water content sensor measurement value collected 0.9s ago.

[0047] S4, the control system uses the material moisture content index as input, the filtered moisture content value as feedback, and adopts a fuzzy semi-closed loop control algorithm to adjust the speed of the servo motor of the homogenizer softener in real time, so that the measurement value of the moisture content sensor at the outlet of the homogenizer softener is close to the oil moisture content index.

[0048] The fuzzy semi-closed loop-based oil elastic-plastic control algorithm is specifically:

[0049] Every 10 seconds, the moisture content error MC is obtained according to the filtered moisture content value. err and moisture content error change rate MC ec_err, and obtain the speed output value O according to the fuzzy control rule, the speed output value O is multiplied by the correction factor K p Get the speed output correction value V offset , through the speed output correction value V offset The speed value of the servo motor of the homogenizer and softener is adjusted as the target value.

[0050] The correction factor K p To limit the steady-state error and overshoot, in this example, K p =0.5.

[0051] Furthermore, the moisture content error MC err =MC ref -MC fdb , where MC ref is the index of oil water content, MC fdb is the moisture content value after filtering; the moisture content error change rate MC ec_err =MC err -MC err_temp , where MC err_temp is the moisture content error of the last time.

[0052] Furthermore, the fuzzy control rules are specifically as follows:

[0053] O=O temp ×(K E ×MC err +K C ×MC ec_err )

[0054] In the formula, O temp is the last speed output value, K E is the moisture content error quantification factor. In this example, K E =0.8, K C is the quantitative factor of the moisture content error change rate. In this example, K C =5.

[0055] Furthermore, the moisture content error quantification factor K E =n / X E , where n is the fuzzy set domain of moisture content error, X E is the basic domain of moisture content error; the moisture content error change rate quantification factor K C =m / X C , where m is the fuzzy set domain of the moisture content error change rate, X C It is the basic domain of moisture content error change rate.

[0056] Furthermore, the design of the membership function of the fuzzy control rule and the fuzzy control rule is mainly used to ensure the dynamic characteristics of the system when the moisture content error is large; and to ensure the steady-state characteristics of the system when the moisture content error is small.

[0057] like Figures 2 to 4 As shown in Figure 2, the design of the membership function takes into account the following two principles:

[0058] 1. For fuzzy subsets with larger errors, a relatively gentle membership function is selected to ensure stability, and for fuzzy subsets with smaller errors, a sharper membership function is selected to ensure high sensitivity of the system.

[0059] 2. To ensure that there is no control dead zone when the system switches between fuzzy subsets, the maximum membership degree of the intersection of each fuzzy subset cannot be too small, and should be between 0.4 and 0.8.

[0060] 2. Oil continuous softening device

[0061] Based on the same inventive concept, an embodiment of the present application also provides an oil continuous softening device, which adopts the oil elastic-plastic control algorithm based on a fuzzy semi-closed loop as described above.

[0062] like Figure 5 As shown, it specifically includes a receiving tank 1 for roasted seeds, an oil elevator 2, a homogenizer and softener 3, a storage tank 4 for softened oil, a steam generator 6 and a control system (a PLC control system in this example).

[0063] The seed-roasted receiving tank 1 is connected to the feed port of the homogenizer and softener 3 through the oil elevator 2, the steam generator 6 is connected to the air inlet of the homogenizer and softener 3 through the steam regulating valve 7, a servo motor 9 is provided at one end of the homogenizer and softener 3, and a discharge port 5 is provided at the bottom of the other end, and the softened oil storage tank 4 is provided directly below the discharge port 5;

[0064] Steam and oil enter the homogenizer softener simultaneously through the air inlet and the feed inlet. As the servo motor drives the homogenizer softener to rotate, the oil fully and evenly absorbs the moisture and energy of the steam, thereby achieving the effect of softening the oil.

[0065] Furthermore, a moisture sensor 8 is provided near the outlet 5 of the homogenizer softener 3 for collecting the moisture content of the oil at the outlet of the homogenizer softener in real time. The moisture sensor 8 sends the collected value to the PLC control system in real time for processing.

[0066] Furthermore, the PLC control system is provided with a human-computer interaction interface for inputting the elastic-plastic index of the oil;

[0067] The moisture content sensor 8 and the drive motor 9 are both electrically connected to the PLC control system. The PLC control system controls the rotation speed of the servo motor 9, thereby controlling the moisture content of the oil at the outlet of the homogenizer softener.

[0068] Based on the same inventive concept, an embodiment of the present application also provides a controller (in this example, a Siemens S1500-PLC controller), including a memory, a processor, and a program stored in the memory and executable on the processor. When the processor executes the program, it implements a fuzzy semi-closed loop-based oil elastic-plastic control algorithm as described above.

[0069] In summary, the oil elastic-plastic control algorithm based on fuzzy semi-closed loop of the present invention is adopted:

[0070] 1. The oil elastic-plastic control is converted into oil moisture content control, and the moisture content error and the moisture content error change rate are comprehensively considered. The fuzzy control rule is used to control the speed value of the servo motor of the homogenizer softener, which can improve the control accuracy of the oil softening device on the oil elastic-plastic property, and has good real-time performance and robustness.

[0071] 2. A relationship table between oil elasticity and plasticity and water content has been established. Combined with the human-computer interaction interface of the control system, the oil elasticity and plasticity index can be quickly converted into the corresponding oil water content index;

[0072] 3. A weighted recursive average filtering method is proposed to filter the moisture content feedback value of the oil at the outlet of the homogenizer softener, which can improve the stability of fuzzy control.

[0073] The above embodiments are only used to illustrate the design ideas and features of the present invention, and their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. The protection scope of the present invention is not limited to the above embodiments. Therefore, any equivalent changes or modifications made based on the principles and design ideas disclosed by the present invention are within the protection scope of the present invention.

Claims

1. A fuzzy semi-closed loop based oil elastic-plastic control algorithm for controlling an oil continuous softening device, characterized in that: The steps include: S1, the user inputs the elastic-plastic index of oil through the human-computer interaction interface; S2, the control system obtains the oil water content index corresponding to the oil elastic-plastic index by searching the oil elastic-plastic and water content relationship table; S3, the control system uses a weighted recursive average filtering method to filter the moisture content sensor measurement value at the outlet of the homogenizer softener to obtain a filtered moisture content value; S4, the control system uses the oil moisture content index as input and the filtered moisture content value as feedback, and adopts a fuzzy semi-closed loop control algorithm to adjust the speed of the servo motor of the homogenizer softener in real time, so that the measurement value of the moisture content sensor at the outlet of the homogenizer softener is close to the oil moisture content index.

2. The oil elastic-plastic control algorithm based on fuzzy semi-closed loop according to claim 1 is characterized by: The relationship table between the elastic-plastic properties of oil and the water content is obtained through laboratory measurements.

3. The oil elastic-plastic control algorithm based on fuzzy semi-closed loop according to claim 1 is characterized in that: The weighted recursive average filtering method is specifically as follows: the moisture sensor measurement value is collected once every 0.1s, the 10 consecutive sample values ​​are set as a queue, each new value collected is put at the end of the queue, and the value at the head of the queue is removed, and finally the weighted average value of the 10 values ​​in the queue is calculated to obtain the filtered moisture content value.

4. The oil elastic-plastic control algorithm based on fuzzy semi-closed loop according to claim 3 is characterized in that: The specific formula of the water content value after filtering is: MC fdb =(A1*MC fdb1 +A2MC fdb2 +.....+A n MC fdbn ) / (A1+A2+.....+A n ) In the formula, MC fdb is the moisture content value after filtering, MC fdb1 is the moisture content sensor measurement value collected this time, MC fdbn is the moisture content sensor measurement value collected for the nth time, A1, A2, A3.....A n is the weighted array for calculating the weighted average, and A1>A2>A3.....>A n .

5. The oil elastic-plastic control algorithm based on fuzzy semi-closed loop according to claim 1 is characterized in that: The oil elastic-plastic control algorithm based on fuzzy semi-closed loop is specifically as follows: Every 10 seconds, the moisture content error MC is obtained according to the filtered moisture content value. err and moisture content error change rate MC ec_err , and obtain the speed output value O according to the fuzzy control rule, the speed output value O is multiplied by the correction factor K P Get the speed output correction value V offset , through the speed output correction value V offset The speed value of the servo motor of the homogenizer and softener is adjusted as the target value.

6. The oil elastic-plastic control algorithm based on fuzzy semi-closed loop according to claim 5 is characterized by: The moisture content error MC err =MC ref -MC fdb , where MC ref is the index of oil water content, MC fdb is the moisture content value after this filtering; The moisture content error change rate MC ec_err =MC err -MC err_temp , where MC err_temp is the moisture content error of the last time.

7. The oil elastic-plastic control algorithm based on fuzzy semi-closed loop according to claim 5 is characterized in that: The fuzzy control rules are specifically: O=O temp ×(K E ×MC err +K C ×MC ec_err ) In the formula, O temp is the last speed output value, K E is the moisture content error quantification factor, K C is the quantitative factor of the moisture content error change rate.

8. The oil elastic-plastic control algorithm based on fuzzy semi-closed loop according to claim 7 is characterized by: The moisture content error quantification factor K E =n / X E , where n is the fuzzy set domain of moisture content error, X E is the basic domain of moisture content error; the moisture content error change rate quantification factor K C =m / X C , where m is the fuzzy set domain of the moisture content error change rate, X C It is the basic domain of moisture content error change rate.

9. An oil continuous softening device using the control algorithm according to any one of claims 1 to 8, characterized in that: The invention comprises a seed-roasting receiving tank (1), an oil lifting machine (2), a homogenizer (3), a softened oil storage tank (4), a steam generator (6) and a control system. The seed-roasting receiving tank (1) is connected to the feed port of the homogenizer (3) through the oil lifting machine (2). The steam generator (6) is connected to the air inlet of the homogenizer (3) through a steam regulating valve (7). A servo motor (9) is provided at one end of the homogenizer (3) and a discharge port (5) is provided at the bottom of the other end. The softened oil storage tank (4) is provided directly below the discharge port (5). The homogenizer (3) is provided with a moisture content sensor (8) near the discharge port (5), the control system is provided with a human-machine interface, and the moisture content sensor (8) and the servo motor (9) are both electrically connected to the control system.

10. A controller comprising a memory, a processor and a program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the control algorithm according to any one of claims 1 to 8 is implemented.

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