CN112903233A - Optimization method for accurate positioning of two-stage series servo oil cylinder driving attack angle mechanism - Google Patents
Optimization method for accurate positioning of two-stage series servo oil cylinder driving attack angle mechanism Download PDFInfo
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Abstract
The invention discloses an optimization method for accurately controlling a two-stage series servo oil cylinder driving angle-of-attack mechanism, which is realized based on an angle-of-attack mechanism and a servo control system, wherein the angle-of-attack mechanism comprises a support rod, a semi-curved knife mechanism, an arc guide rail, a primary servo oil cylinder and a secondary servo oil cylinder, each stage of the two-stage series servo oil cylinder adopts an independent oil supply mode, and the oil cylinders are provided with two position encoders and adopt the servo system for closed-loop control. The invention is mainly used for solving the practical problems that the position of an angle-of-attack mechanism cannot be closed-loop, speed mutation is generated and accurate positioning cannot be realized due to the fact that two-stage series servo oil cylinders for driving the angle-of-attack mechanism in a certain supersonic wind tunnel adopt a control method of proportional distribution and direct positioning according to stroke.
Description
Technical Field
The invention belongs to the electromechanical liquid and automation technology, relates to the precise positioning of an angle of attack mechanism in a wind tunnel test, and particularly relates to an optimization method for the precise positioning of a two-stage series servo oil cylinder driven angle of attack mechanism.
Background
Wind tunnel test data is important support data for aircraft development, and can verify the correctness and feasibility of related schemes. The ultrasonic wind tunnel is an injection type temporary impact direct current ultrasonic supercharging wind tunnel, the throwing test section is a special test section of the ultrasonic wind tunnel, the ultrasonic wind tunnel can be used for special tests such as CTS tests, throwing tests and the like, and the throwing mechanism is a main moving part.
The throwing mechanism has three degrees of freedom and is defined by a Cartesian coordinate system. Wherein, the X direction is the direction of the following airflow of the wind tunnel, the Y direction is the direction of the lifting force of the model, the attack angle alpha is the direction of the test model rotating around the Z direction, and the clockwise direction is positive. The throwing mechanism consists of an X-direction mechanism, a Y-direction mechanism and an attack angle mechanism. Wherein, the attack angle mechanism is driven by two-stage series servo oil cylinders. The two-stage series servo oil cylinder consists of two stages, and the second stage oil cylinder is sleeved in the first stage oil cylinder.
In the design of the prior period, the two-stage series servo oil cylinders generally adopt an optimization method of proportional distribution and direct positioning according to the stroke to realize the accurate positioning of the attack angle of the mechanism. In practical application, however, the problem that the position of an attack angle mechanism cannot be closed and accurate positioning cannot be achieved easily in certain angle ranges is found, and meanwhile, the phenomenon of sudden speed change in an excessive stage is accompanied. Through a plurality of experimental analyses, the method comprises the following steps: the two-stage series servo oil cylinder is of a nested structure and consists of an inner cylinder and an outer cylinder, wherein the inner cylinder is nested in the outer cylinder, the rod diameter is small, and the output force is insufficient; under the limit working condition, when the attack angle of the mechanism moves in a certain angle range, the output force characteristic of the inner cylinder can not meet the actual requirement, and then the problems that the position of the mechanism can not be closed and the speed changes suddenly are caused.
In order to realize stable control of the angle of attack motion and high-precision positioning, the precise positioning method of the two-stage series servo oil cylinder driving angle of attack mechanism needs to be optimized so as to meet the requirements of wind tunnel tests and provide precise data support for aircraft development.
Disclosure of Invention
The invention provides an optimization method for accurately positioning a two-stage series servo oil cylinder driving angle-of-attack mechanism, aiming at solving the practical problems that the two-stage series servo oil cylinder driving angle-of-attack mechanism in the prior art adopts an optimization method of proportional distribution and direct positioning according to stroke, so that the angle-of-attack mechanism cannot be positioned in a closed loop, speed mutation is generated, and accurate positioning cannot be realized.
In order to achieve the purpose, the invention provides the following technical scheme.
An optimization method for accurate positioning of a two-stage series servo oil cylinder driving attack angle mechanism is realized based on an attack angle mechanism and a servo control system; the angle-of-attack mechanism comprises a supporting rod, a semi-curved knife mechanism, an arc guide rail, a primary servo oil cylinder and a secondary servo oil cylinder, a test model is arranged on the semi-curved knife mechanism through the supporting rod, the primary servo oil cylinder serves as an outer cylinder, the secondary servo oil cylinder serves as an inner cylinder and is connected in series to form a two-stage series servo oil cylinder, the two-stage series servo oil cylinder is hinged with the semi-curved knife mechanism, and the two-stage series servo oil cylinder drives the semi-curved knife mechanism to slide along the arc guide rail so as to drive the test model to rotate around a model rotation center, so that the change of; the servo control system comprises an oil source system, a primary servo oil cylinder servo valve, a secondary servo oil cylinder servo valve, a PLC (programmable logic controller) core controller, a primary servo oil cylinder position encoder and a secondary servo oil cylinder position encoder; the primary servo oil cylinder position encoder and the secondary servo oil cylinder position encoder are respectively arranged on the primary servo oil cylinder and the secondary servo oil cylinder; the PLC core controller is respectively connected with the primary servo oil cylinder position encoder and the secondary servo oil cylinder position encoder through position feedback signal cables, and is also respectively connected with the primary servo oil cylinder servo valve and the secondary servo oil cylinder servo valve through control signal cables; the primary servo oil cylinder servo valve and the secondary servo oil cylinder servo valve are respectively connected with the primary servo oil cylinder and the secondary servo oil cylinder through oil inlet/return pipelines; the oil source system is respectively connected with the primary servo oil cylinder servo valve and the secondary servo oil cylinder servo valve through an oil inlet/return pipeline; the oil source system supplies/returns oil to a servo valve of the primary servo oil cylinder and a servo valve of the secondary servo oil cylinder, the PLC core controller controls the oil inlet/return flow of the primary servo oil cylinder and the secondary servo oil cylinder according to the set elevation angle so as to realize the accurate positioning of the primary servo oil cylinder and the secondary servo oil cylinder, and the position encoder of the primary servo oil cylinder and the position encoder of the secondary servo oil cylinder respectively detect the strokes of the primary servo oil cylinder and the secondary servo oil cylinder and transmit stroke data to the PLC core controller in real time; and the PLC core controller receives the stroke data in real time and is used for controlling the closed loop.
The optimization method comprises the following steps:
s1, according to the design of the angle of attack mechanism, obtaining a functional relationship α ═ f (l) between the angle of attack α and the total stroke l of the two-stage series servo cylinder, and determining a design parameter value range between the angle of attack α of the angle of attack mechanism and the total stroke l of the two-stage series servo cylinder:
in the formula I1、l2The stroke of the first-stage servo oil cylinder and the stroke of the second-stage servo oil cylinder are respectively, and f is a relation criterion of an attack angle alpha and a total stroke l of the two-stage series servo oil cylinders and is obtained by structural design parameters;
s2, obtaining the angle of attack alpha of the angle of attack mechanism and the actual parameter value range of the total stroke l of the two-stage series servo oil cylinder through single action before debugging;
s3, determining an operation limit working condition according to the structural form of the angle-of-attack mechanism and the two-stage series servo oil cylinder and the output force parameters of the first-stage and the second-stage servo oil cylinders, wherein the limit working condition is that the output force of the first-stage and the second-stage servo oil cylinders is opposite to the tangential component force direction of the gravity of the half-bent cutter mechanism acting on the half-bent cutter mechanism;
s4, under the limit working condition, carrying out stress analysis on the half-bent knife mechanism: under the working condition, the first-stage and second-stage servo oil cylinders independently drive the half-bent blade mechanism to move to obtain a resultant force f between an attack angle alpha and a tangential resultant force f of the first-stage and second-stage servo oil cylinders acting on the half-bent blade of the attack angle mechanismT1、fT2A relation curve;
s5 tangential resultant force f acting on half-bent knife of angle-of-attack mechanism based on angle-of-attack alpha and primary and secondary servo oil cylindersT1、fT2And (3) preliminarily distributing the total stroke l of the two-stage series servo oil cylinders corresponding to the attack angle alpha according to a relation curve, wherein the distribution principle is as follows: when the tangential resultant force of the two-stage servo oil cylinders serving as the inner cylinder can not drive the mechanism to move, primarily setting that the primary oil cylinder drives the attack angle mechanism to move independently, and finishing the attack angle positioning of the mechanism by the linkage of the primary and secondary servo oil cylinders in other areas;
s6, further optimizing on the basis of S5, and constructing a buffer mechanism: setting up mechanism incidence angle running buffer area [ alpha ]1α2]，α1<α2And the actual value range of the attack angle alpha of the attack angle mechanism is obtained in step S2. Determining the motion rule of two-stage series servo oil cylinders in each area: when alpha is<α1When the system is used, a single driving mechanism of a certain stage of servo oil cylinder operates; when alpha is>α2When the system is used, the other stage of servo oil cylinder independently drives the mechanism to operate; when alpha is1≤α≤α2In time, the two servo oil cylinders are linked; finally determining the motion rule of the two-stage series servo oil cylinders in each area through theoretical analysis and calculation;
s7, under the condition that the functional relation between the attack angle alpha and the total stroke l of the two-stage series servo oil cylinder is not changed, performing position interpolation by adopting a high-order curve to ensure that the first-stage servo oil cylinder and the second-stage servo oil cylinder move smoothly without generating speed mutation; continuously iterating and optimizing to obtain final mechanism attack angle running buffer area alpha1α2]；
S8, and obtaining a buffer area [ alpha ] according to the motion rule and optimization of the two-stage series servo oil cylinder in each area determined in the steps S6 and S71α2]And selecting an attack angle alpha and a stroke l of the primary and secondary servo oil cylinders according to actual debugging1、l2Embedding the corresponding position points into a PLC (programmable logic controller) system for curve fitting;
s9, during testing, the PLC control system inquires curve values according to target angles and controls the primary and secondary servo oil cylinders to strictly operate according to curves, so that the accurate positioning of the attack angle of the mechanism is realized, the stable operation of the mechanism is ensured, and no speed sudden change occurs.
According to the optimization method for the accurate positioning of the two-stage series servo oil cylinder driving attack angle mechanism, the inventor carries out a great deal of analysis on the stability/control accuracy and other dynamic and steady-state performances of the control system in the test process, so that the optimization method capable of meeting the control requirements is provided. The method is characterized in that a relation alpha (f) (l) between an attack angle alpha and a total stroke l of the two-stage series servo oil cylinder is taken as a basis, design parameters and actual parameters of the attack angle and the total stroke l of the oil cylinder are determined in sequence, a limit working condition is determined according to the structural form of an attack angle mechanism and the output force characteristic of the oil cylinder, and a half cutter bending mechanism under the limit working condition is subjected to stress analysis, so that the primary optimized distribution of the total stroke of the two-stage series servo oil cylinder is carried out, and the motion rule of the two-stage series servo oil cylinder is set preliminarily; further optimizing and setting up a mechanism attack angle running buffer area, setting a two-stage series servo oil cylinder movement rule in each area, carrying out position interpolation by adopting a high-order curve to ensure that the first and second stages of servo oil cylinders move smoothly, and then combining debugging and continuous iterative optimization to obtain a final mechanism attack angle running buffer area; and then selecting a proper attack angle and corresponding position points of the strokes of the primary and secondary servo oil cylinders, embedding the suitable attack angle and the corresponding position points into a PLC (programmable logic controller) system, and accurately positioning the PLC system according to the position points to ensure that the mechanism runs stably without speed mutation.
According to the optimization method for the accurate positioning of the driving angle-of-attack mechanism of the two-stage series servo oil cylinder, each stage of the two-stage series servo oil cylinder adopts an independent oil supply mode, so that the influence on the operation accuracy of the oil cylinder caused by the fact that the oil inlet amount of the large and small cylinders cannot be controlled is prevented; the oil cylinder adopts a servo system to carry out closed-loop control, so that the accurate control of the motion position of the oil cylinder can be realized; the oil cylinder is provided with two sets of position encoders, so that the stroke of each stage of oil cylinder can be accurately transmitted and detected, and the problem of high positioning precision of an angle-of-attack mechanism can be solved.
In the method for optimizing the accurate positioning of the two-stage series servo oil cylinder driving attack angle mechanism, under a general condition, the value range of a design parameter of the attack angle alpha of the attack angle mechanism and the total stroke l of the two-stage series servo oil cylinder is different from the value range of an actual parameter. In step S1, the design parameter value range is: alpha is more than or equal to 10 degrees and less than or equal to 40 degrees, and l is more than or equal to 0mm and less than or equal to 2274 mm; when l is 0mm, α is-10 °. In step S2, the actual parameter value range is: alpha is more than or equal to minus 9 degrees and less than or equal to 39 degrees, and l is more than or equal to 49mm and less than or equal to 2310 mm.
In the method for optimizing the accurate positioning of the two-stage series servo cylinder driven attack angle mechanism, in step S3, the output force parameters include parameters of push-out force and pull-back force of the first-stage servo cylinder/the second-stage servo cylinder.
According to the optimization method for the accurate positioning of the two-stage series servo oil cylinder driven attack angle mechanism, on the basis of the design parameter value range and the actual parameter value range, the stress analysis condition of the half-bent knife mechanism is combined, in a general situation, in step S5, according to the stress analysis in step S4, the initial setting is carried out in a region of alpha being more than or equal to-9 degrees and less than or equal to-4 degrees, and the attack angle of the mechanism is driven by the first-stage servo oil cylinder alone to move from large to small; -4 °<Alpha is less than or equal to 39 degrees, and the first-stage servo oil cylinder and the second-stage servo oil cylinder are linked to realize the movement of the attack angle of the mechanism from big to small. And in step S6, alpha1>-4°，α1<α2<39°。
According to the method for optimizing the accurate positioning of the two-stage series servo oil cylinder driving attack angle mechanism, in the steps S8 and S9, position points corresponding to the strokes of the first-stage servo oil cylinder and the second-stage servo oil cylinder are selected according to actual debugging and embedded into a PLC (programmable logic controller) system, and the PLC system performs curve fitting; during the test, curve numerical query is carried out according to the target attack angle, and the primary servo oil cylinder and the secondary servo oil cylinder are controlled to strictly operate according to a fitting curve, so that the accurate positioning of the attack angle of the mechanism is realized.
Compared with the prior art, the technical scheme provided by the invention has the following beneficial technical effects:
the invention provides an optimization method for accurate positioning of a two-stage series servo oil cylinder driving attack angle mechanism, which is characterized in that according to the position motion relation between a mechanism attack angle and the total stroke of two-stage series servo oil cylinders, a buffer mechanism is constructed on the basis of carrying out stress analysis on a half-bent knife mechanism under a limit working condition, and the motion rule of the two-stage series servo oil cylinders in each area is determined; introducing a high-order curve to perform position interpolation, combining debugging and continuously performing iterative optimization to obtain a final mechanism attack angle running buffer area; according to actual debugging, selecting position points corresponding to the attack angle and the strokes of the primary and secondary servo oil cylinders, embedding the position points into a PLC (programmable logic controller) system, and performing curve fitting; during the test, the PLC system strictly controls the primary and secondary servo oil cylinders to carry out accurate positioning according to the fitting curve, and then the accurate positioning of the attack angle of the mechanism is completed. The invention effectively solves the problems that the mechanism cannot be closed in position and suddenly changed in speed when the angle-of-attack mechanism moves in a certain angle range under the limit working condition caused by the fact that the two-stage series nested servo oil cylinder is adopted to drive the angle-of-attack mechanism in a certain supersonic wind tunnel and the inner cylinder rod diameter is small and the output force is insufficient, thereby ensuring the stable operation of the mechanism and improving the operation safety of the mechanism.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other embodiments and drawings can be obtained according to the embodiments shown in the drawings without creative efforts.
FIG. 1 is a schematic view of a two-stage series servo cylinder driving attack angle mechanism and a servo control system according to the present invention;
FIG. 2 is a schematic flow chart of an optimization method for accurate positioning of a two-stage series servo cylinder driven attack angle mechanism according to the present invention;
FIG. 3 is a schematic view of the movement of the angle of attack mechanism;
FIG. 4 is a force analysis of the half-curved knife mechanism when the mechanism angle of attack moves from large to small. Wherein: f. ofαTIs a tangential component force f of the retraction force of the oil cylindermTThe tangential component force of the gravity of the half-curved cutter, mg is the gravity of the half-curved cutter, and alpha is the attack angle;
FIG. 5 shows the resultant force f between the angle of attack alpha and the tangential force f of the first and second servo cylinders acting on the half-curved knife when the angle of attack of the mechanism moves from large to smallT1、fT2And (5) a relation curve (assuming that the first-stage servo oil cylinder and the second-stage servo oil cylinder drive the angle-of-attack mechanism to move independently). Wherein: f. ofT1、fT2Respectively a tangential direction of a primary servo oil cylinder and a secondary servo oil cylinder acting on a half-curved knifeCombining the forces;
FIG. 6 shows the optimized mechanism attack angle α and the stroke l of the first and second servo cylinders1、l2The fitted curve of (1). Wherein: l1、l2Respectively the stroke of the first-stage servo oil cylinder and the stroke of the second-stage servo oil cylinder; l is the total stroke of the two-stage servo oil cylinder.
Description of reference numerals: 1. a test model; 2. a strut; 3. a semi-curved knife mechanism; 4. a primary servo oil cylinder; 5. a secondary servo oil cylinder; 6. a circular arc guide rail; 7. a model center of rotation; 8. an oil source system; 9. a primary servo oil cylinder servo valve; 10. a secondary servo oil cylinder servo valve; 11. a primary servo oil cylinder servo valve oil inlet/return pipeline; 12. an oil inlet/return pipeline of a servo valve of the secondary servo oil cylinder; 13. a primary servo oil cylinder oil inlet/return pipeline; 14. a secondary servo oil cylinder oil inlet/return pipeline; 15. a PLC core controller; 16. a servo valve control signal cable of the primary servo oil cylinder; 17. a signal cable is controlled by a servo valve of the secondary servo oil cylinder; 18. a signal cable is fed back by the position of the primary servo oil cylinder; 19. a signal cable is fed back by the position of the secondary servo oil cylinder; 20. a primary servo oil cylinder position encoder; 21. and a position encoder of the secondary servo oil cylinder.
Detailed Description
The technical solutions of the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings, and it is to be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In this embodiment, an optimization method for accurately positioning a two-stage series servo oil cylinder driven attack angle mechanism in a three-degree-of-freedom delivery mechanism of an ultrasonic wind tunnel is described in combination with a corresponding servo control system.
Two-stage series servo oil cylinder driving attack angle mechanism and servo control system in a certain supersonic wind tunnel three-degree-of-freedom throwing mechanism are shown in figure 1. The attack angle mechanism comprises a test model 1, a support rod 2, a semi-curved knife mechanism 3, a primary servo oil cylinder 4, a secondary servo oil cylinder 5 and an arc guide rail 6. The test model 1 is arranged on the half-curved knife mechanism 3 through the supporting rod 2, the first-stage servo oil cylinder 4 serves as an outer cylinder, the second-stage servo oil cylinder 5 serves as an inner cylinder and is connected in series to form a two-stage series servo oil cylinder, the two-stage series servo oil cylinder is hinged with the half-curved knife mechanism 3, the two-stage series servo oil cylinder drives the half-curved knife mechanism 3 to slide along the arc guide rail 6, so that the test model 1 is driven to rotate around the model rotation center 7, and the change of the attack angle alpha of the test model 1 is achieved. The servo control system comprises an oil source system 8, a primary servo oil cylinder servo valve 9, a secondary servo oil cylinder servo valve 10, a primary servo oil cylinder servo valve oil inlet/return pipeline 11, a secondary servo oil cylinder servo valve oil inlet/return pipeline 12, a primary servo oil cylinder oil inlet/return pipeline 13, a secondary servo oil cylinder oil inlet/return pipeline 14, a PLC core controller 15, a primary servo oil cylinder servo valve control signal cable 16, a secondary servo oil cylinder servo valve control signal cable 17, a primary servo oil cylinder position feedback signal cable 18, a secondary servo oil cylinder position feedback signal cable 19, a primary servo oil cylinder position encoder 20 and a secondary servo oil cylinder position encoder 21.
The oil source system 8 supplies oil to/returns oil from the primary servo oil cylinder servo valve 9 and the secondary servo oil cylinder servo valve 10 through a primary servo oil cylinder servo valve oil inlet/return pipeline 11 and a secondary servo oil cylinder servo valve oil inlet/return pipeline 12 respectively. The primary servo oil cylinder servo valve 9 and the secondary servo oil cylinder servo valve 10 are respectively connected with the primary servo oil cylinder 4 and the secondary servo oil cylinder 5 through a primary servo oil cylinder oil inlet/return pipeline 13 and a secondary servo oil cylinder oil inlet/return pipeline 14. The PLC core controller 15 is respectively connected with the primary servo oil cylinder servo valve 9 and the secondary servo oil cylinder servo valve 10 through a primary servo oil cylinder servo valve control signal cable 16 and a secondary servo oil cylinder servo valve control signal cable 17, the oil inlet/return flow is accurately controlled, the accurate positioning of the primary servo oil cylinder 4 and the secondary servo oil cylinder 5 is realized, and the accurate positioning of the attack angle of the test model 1 is further realized. The PLC core controller 15 is respectively connected with a primary servo oil cylinder position encoder 20 and a secondary servo oil cylinder position encoder 21 through a primary servo oil cylinder position feedback signal cable 18 and a secondary servo oil cylinder position feedback signal cable 19, so that the accurate positions of the primary servo oil cylinder 4 and the secondary servo oil cylinder 5 are obtained in real time and are used for position control closed loop.
As shown in fig. 2, the invention determines design parameters and actual parameters of an attack angle and a total stroke of an oil cylinder on the basis of a relationship alpha (f) (l) between the attack angle alpha and the total stroke l of the two-stage series servo oil cylinder, determines a limit working condition according to a structural form of an attack angle mechanism and output force characteristics of the oil cylinder, and performs stress analysis on a half-cutter mechanism under the limit working condition, thereby performing preliminary optimized distribution of the total stroke of the two-stage series servo oil cylinder, and preliminarily setting a motion rule of the two-stage series servo oil cylinder; further setting up a mechanism attack angle running buffer area, setting a two-stage series servo oil cylinder movement rule in each area, carrying out position interpolation by adopting a high-order curve to ensure that the first and second stages of servo oil cylinders move smoothly, and then combining debugging and continuous iterative optimization to obtain a final mechanism attack angle running buffer area; and then selecting a proper attack angle and a position point corresponding to the stroke of the primary and secondary servo oil cylinders, embedding the selected position point into a PLC (programmable logic controller) system, and accurately positioning the position point by the PLC system.
The simplified movement of the two-stage series servo oil cylinder driving attack angle mechanism in the three-degree-of-freedom releasing mechanism of a certain supersonic wind tunnel is schematically shown in fig. 3, wherein A is a fixed rotation center of the root of a series two-stage oil cylinder; o is the rotation center of the half-curved knife mechanism; b is a connection rotating point of the serial two-stage oil cylinder and the semi-curved knife mechanism, and the connection rotating point moves circularly around the point O; alpha is the mechanism attack angle; b is0Is the position point of B when alpha is 0, and the attack angle offset alpha is obtained0(ii) a When B is from B0Point movement from B1And obtaining the mechanism attack angle alpha when in point. In fig. 3: OA-4816.3 mm, OB-3115.9 mm, when AB-AB0When the cylinder axis of the two-stage oil cylinder is 2020mm, alpha is 0 degrees, and an included angle of 10 degrees is formed between the cylinder axis of the two-stage oil cylinder in series connection and the horizontal direction; α -10 ° when AB 1751 mm; alpha is more than or equal to minus 10 degrees and less than or equal to 40 degrees, and l is more than or equal to 0mm and less than or equal to 2274 mm.
The optimization method specifically comprises the following steps:
s1, obtaining the attack angle alpha of the mechanism, the total stroke l of the two-stage series servo oil cylinder, the total stroke l and the line l of the first and second stages servo oil cylinder according to the design of the mechanism1、l2Functional relationship:
mechanism design parameters: alpha is more than or equal to 10 degrees and less than or equal to 40 degrees, and l is more than or equal to 0mm and less than or equal to 2274 mm; when l is 0mm, α is-10 °.
S2, determining the actual parameters of the angle of attack mechanism by single action before debugging: alpha is more than or equal to 9 degrees and less than or equal to 39 degrees, and l is more than or equal to 49mm and less than or equal to 2310 mm;
s3, analyzing the output force parameters (extension 566000N and retraction 204000N) of the primary servo cylinder and the output force parameters (extension 221000N and retraction 106000N) of the secondary servo cylinder according to the structural form of the angle-of-attack mechanism: when the attack angle alpha of the mechanism is reduced from large to small and the two stages of servo oil cylinders both do retraction movement, the output force of the two stages of servo oil cylinders is small and the gravity of the half-bent knife mechanism needs to be overcome, so that the working condition is determined to be a limit working condition.
And S4, analyzing the motion stress of the half-bent knife mechanism under the limit working condition, as shown in figure 4. In fig. 4: the connecting point of the oil cylinder and the half-bent knife mechanism is positioned at B0At the position, the attack angle of the mechanism is 0 and is at B1The attack angle of the mechanism at the position is alpha; when the attack angle alpha of the mechanism is reduced from large to small, the oil cylinder retracts, and the connection point of the oil cylinder and the semi-curved knife mechanism is positioned at B1When in position, the resultant tangential force borne by the half-curved knife mechanism is fT＝fαT-fmT。
According to the weight (6000kg) of the half-curved knife and the retraction output force parameters (204000N, 106000N) of the primary and secondary servo oil cylinders, assuming that the primary and secondary servo oil cylinders drive the half-curved knife mechanism to move independently, the tangential resultant force f acting on the half-curved knife by the primary and secondary servo oil cylinders and the mechanism attack angle alpha are obtainedT1、fT2The relationship is shown in FIG. 5. From fig. 5, it follows: alpha is more than or equal to minus 9 degrees<In the-4 degree area, the tangential resultant force of the two-stage servo oil cylinder (inner cylinder) can not drive the mechanism to move.
S5, based on the obtained conclusion, preliminarily setting the angle of attack of the single driving mechanism in the area of alpha less than or equal to-4 degrees and more than-9 degrees, and moving the single driving mechanism from large to small by the primary servo oil cylinder; alpha is more than or equal to 4 degrees and less than or equal to 39 degrees, and the first-stage servo oil cylinder and the second-stage servo oil cylinder are linked to realize the movement of the attack angle of the mechanism from large to small.
S6, further optimizing, constructing a buffer mechanism, and setting up an organization incidence angle running buffer area of [ -4 degrees 0 degrees ]: when the angle alpha is less than-4 degrees, the single driving mechanism of the primary servo oil cylinder operates; when alpha is more than or equal to 4 degrees and less than or equal to 0 degree, the two stages of servo oil cylinders are linked; when the alpha is less than or equal to 39 degrees and is less than 0 degree, the two-stage servo oil cylinder single driving mechanism operates.
S7, under the condition that the functional relation between the mechanism attack angle alpha and the total stroke l of the two-stage series servo oil cylinders is not changed, position interpolation is carried out by adopting a quadratic fitting curve, so that the first-stage servo oil cylinder and the second-stage servo oil cylinder can be ensured to move smoothly without generating speed mutation; through debugging and continuous iterative optimization, an obtained mechanism attack angle running buffer area is [14 degrees and 21 degrees ].
S8, selecting an attack angle alpha and a stroke l of the primary and secondary servo oil cylinders through debugging1、l2The corresponding position points are embedded into the PLC controller system, and curve fitting is performed by the PLC controller system, as shown in fig. 6. Selecting an attack angle alpha and a stroke l of the primary and secondary servo oil cylinders in the table 11、l2And the position points are embedded into the PLC system, and the PLC system performs curve fitting.
S9, during testing, the PLC control system inquires curve values according to target angles and controls the primary and secondary servo oil cylinders to strictly operate according to curves, so that the accurate positioning of the attack angle of the mechanism is realized, the stable operation of the mechanism is ensured, and no speed sudden change occurs.
TABLE 1 Angle of attack α and Primary and Secondary Servo Cylinder Stroke l1、l2Corresponding position point
By the optimization method, the problems that when a certain large wind tunnel two-stage series servo oil cylinder drives the attack angle mechanism and moves within a small angle range, the generated mechanism cannot be closed in position and suddenly changed in speed are effectively solved, stable and safe operation of the mechanism is realized, and the positioning precision of the attack angle of the mechanism is superior to 0.02 degrees.
In summary, according to the optimization method for the precise positioning of the two-stage series servo oil cylinder driving angle-of-attack mechanism provided by the invention, in the process of controlling the angle-of-attack movement, the two-stage servo oil cylinders adopt a high-order curve to perform position interpolation according to the position movement relation between the two-stage servo oil cylinders and the angle-of-attack, so that the first-stage servo oil cylinder and the second-stage servo oil cylinder are ensured to move smoothly; and combining debugging and continuously iterating and optimizing to obtain a final mechanism attack angle running buffer area, setting motion rules of two stages of series servo oil cylinders in each area, finishing the motion of the two stages of servo oil cylinders under the control of a PLC (programmable logic controller) core controller, and finishing the accurate positioning of the model attack angle by the controller according to a control strategy. The problem that under the limit working condition that a certain large wind tunnel adopts two-stage series nested servo oil cylinders to drive the angle-of-attack mechanism, the angle-of-attack mechanism cannot move in a certain angle range due to the fact that the inner cylinder rod diameter is small and output force is insufficient, the position of the mechanism cannot be closed and speed of the mechanism cannot change suddenly is solved, stable operation of the mechanism is guaranteed, and operation safety of the mechanism is improved.
Claims (7)
1. The optimization method is characterized in that the optimization method is realized based on an angle-of-attack mechanism and a servo control system, the angle-of-attack mechanism comprises a supporting rod, a half-curved knife mechanism, a first-stage servo oil cylinder, a second-stage servo oil cylinder and a circular arc guide rail, a test model is mounted on the half-curved knife mechanism through the supporting rod, the first-stage servo oil cylinder serves as an outer cylinder, the second-stage servo oil cylinder serves as an inner cylinder and is connected in series to form the two-stage series servo oil cylinder, the two-stage series servo oil cylinder is connected with the half-curved knife mechanism in a hinged mode, the two-stage series servo oil cylinder drives the half-curved knife mechanism to slide along the circular arc guide rail so as to drive the test model to rotate around a model rotation center; the servo control system comprises an oil source system, a primary servo oil cylinder servo valve, a secondary servo oil cylinder servo valve, a PLC (programmable logic controller) core controller, a primary servo oil cylinder position encoder and a secondary servo oil cylinder position encoder; the primary servo oil cylinder position encoder and the secondary servo oil cylinder position encoder are respectively arranged on the primary servo oil cylinder and the secondary servo oil cylinder; the PLC core controller is respectively connected with the primary servo oil cylinder position encoder and the secondary servo oil cylinder position encoder through position feedback signal cables, and is also respectively connected with the primary servo oil cylinder servo valve and the secondary servo oil cylinder servo valve through control signal cables; the primary servo oil cylinder servo valve and the secondary servo oil cylinder servo valve are respectively connected with the primary servo oil cylinder and the secondary servo oil cylinder through oil inlet/return pipelines; the oil source system is respectively connected with the primary servo oil cylinder servo valve and the secondary servo oil cylinder servo valve through an oil inlet/return pipeline; the oil source system supplies/returns oil to a primary servo oil cylinder servo valve and a secondary servo oil cylinder servo valve; the PLC core controller controls the oil inlet/return flow of the primary servo oil cylinder and the secondary servo oil cylinder according to the set elevation angle alpha so as to realize the accurate positioning of the primary servo oil cylinder and the secondary servo oil cylinder; the primary servo oil cylinder position encoder and the secondary servo oil cylinder position encoder respectively detect the strokes of the primary servo oil cylinder and the secondary servo oil cylinder and transmit stroke data to the PLC core controller in real time; the PLC core controller receives the stroke data in real time and is used for controlling a closed loop by a position;
the optimization method comprises the following steps:
s1, according to the design of the angle of attack mechanism, obtaining a functional relationship α ═ f (l) between the angle of attack α and the total stroke l of the two-stage series servo cylinder, and determining a design parameter value range between the angle of attack α of the angle of attack mechanism and the total stroke l of the two-stage series servo cylinder:
in the formula I1、l2The stroke of the first-stage servo oil cylinder and the stroke of the second-stage servo oil cylinder are respectively, and f is a relation criterion of an attack angle alpha and a total stroke l of the two-stage series servo oil cylinders and is obtained by structural design parameters;
s2, obtaining the angle of attack alpha of the angle of attack mechanism and the actual parameter value range of the total stroke l of the two-stage series servo oil cylinder through single action before debugging;
s3, determining an operation limit working condition according to the structural form of the angle-of-attack mechanism and the two-stage series servo oil cylinder and the output force parameters of the first-stage and the second-stage servo oil cylinders, wherein the limit working condition is that the output force of the first-stage and the second-stage servo oil cylinders is opposite to the tangential component force direction of the gravity of the half-bent cutter mechanism acting on the half-bent cutter mechanism;
s4, under the limit working condition, carrying out stress analysis on the half-bent knife mechanism: under the working condition, the first-stage and second-stage servo oil cylinders independently drive the half-bent blade mechanism to move to obtain a resultant force f between an attack angle alpha and a tangential resultant force f of the first-stage and second-stage servo oil cylinders acting on the half-bent blade of the attack angle mechanismT1、fT2A relation curve;
s5 tangential resultant force f acting on half-bent knife of angle-of-attack mechanism based on angle-of-attack alpha and primary and secondary servo oil cylindersT1、fT2And (3) preliminarily distributing the total stroke l of the two-stage series servo oil cylinders corresponding to the attack angle alpha according to a relation curve, wherein the distribution principle is as follows: when the tangential resultant force of the two-stage servo oil cylinders serving as the inner cylinder can not drive the mechanism to move, primarily setting that the primary oil cylinder drives the attack angle mechanism to move independently, and finishing the attack angle positioning of the mechanism by the linkage of the primary and secondary servo oil cylinders in other areas;
s6, further optimizing on the basis of S5, and constructing a buffer mechanism: setting up mechanism incidence angle running buffer area [ alpha ]1α2]，α1<α2And the actual value range of the attack angle alpha of the attack angle mechanism is obtained in step S2: setting the motion rule of two-stage series servo oil cylinders in each area: when alpha is<α1When the system is used, a single driving mechanism of a certain stage of servo oil cylinder operates; when alpha is>α2When the system is used, the other stage of servo oil cylinder independently drives the mechanism to operate; when alpha is1≤α≤α2In time, the two servo oil cylinders are linked; finally determining the motion rule of the two-stage series servo oil cylinders in each area through theoretical analysis and calculation;
s7, under the condition that the functional relation between the attack angle alpha and the total stroke l of the two-stage series servo oil cylinder is not changed, performing position interpolation by adopting a high-order curve to ensure that the first-stage servo oil cylinder and the second-stage servo oil cylinder move smoothly without generating speed mutation; continuously iterating and optimizing to obtain final mechanism attack angle running buffer area alpha1α2]；
S8, and obtaining the slow motion rule and optimization of the two-stage series servo oil cylinder motion in each area determined according to the steps S6 and S7Impact zone [ alpha ]1α2]And selecting an attack angle alpha and a stroke l of the primary and secondary servo oil cylinders according to actual debugging1、l2Embedding the corresponding position points into a PLC (programmable logic controller) system for curve fitting;
s9, during testing, the PLC control system inquires curve values according to target angles and controls the primary and secondary servo oil cylinders to strictly operate according to curves, so that the accurate positioning of the attack angle of the mechanism is realized, the stable operation of the mechanism is ensured, and no speed sudden change occurs.
2. The optimization method for the accurate positioning of the two-stage series servo oil cylinder driving attack angle mechanism according to claim 1, characterized in that the value range of the design parameter of the attack angle α of the attack angle mechanism and the total stroke l of the two-stage series servo oil cylinder is different from the value range of the actual parameter.
3. The method for optimizing the accurate positioning of the two-stage series servo cylinder driven attack angle mechanism according to claim 2, wherein in step S1, the range of the design parameters is as follows: alpha is more than or equal to 10 degrees and less than or equal to 40 degrees, and l is more than or equal to 0mm and less than or equal to 2274 mm; when l is 0mm, α is-10 °.
4. The method for optimizing the accurate positioning of the two-stage series servo cylinder driven attack angle mechanism according to claim 2, wherein in step S2, the actual parameter value range is as follows: alpha is more than or equal to minus 9 degrees and less than or equal to 39 degrees, and l is more than or equal to 49mm and less than or equal to 2310 mm.
5. The method for optimizing the precise positioning of a two-stage tandem servo cylinder driven angle of attack mechanism according to any one of claims 1 to 4, wherein in step S3, the output force parameters include parameters of push-out force and pull-back force of the primary/secondary servo cylinder.
6. The method for optimizing the precise positioning of the two-stage series servo oil cylinder driving attack angle mechanism according to any one of claims 1 to 4, wherein in step S5, according to the stress analysis of step S4, the initial setting is performed in the area where the angle alpha is more than or equal to-9 degrees and less than or equal to-4 degrees, and the attack angle of the mechanism is driven by the single one-stage servo oil cylinder to move from large to small; and in the range of alpha less than or equal to 39 degrees of minus 4 degrees, the first-stage servo oil cylinder and the second-stage servo oil cylinder are linked to realize the movement of the attack angle of the mechanism from large to small.
7. The method for optimizing the precise positioning of a two-stage tandem servo cylinder driven angle of attack mechanism as claimed in any one of claims 1 to 4, wherein in step S6, α is1>-4°，α1<α2<39°。
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