A model posture mechanism control method adaptive to double-cylinder linkage large overrunning load

Abstract

The application discloses a model posture mechanism control method suitable for double-cylinder linkage large-exceeding load, and belongs to the technical field of model posture mechanism control. The method comprises the following steps: judging the running direction of the angle mechanism and the positive and negative directions of the upper and lower oil cylinders; calculating the displacement difference of the upper and lower oil cylinders corresponding to the target angle and the current angle; adopting a differentiated control strategy according to the running direction of the angle mechanism; when the angle mechanism runs in the negative direction, implementing segmented self-adaptive variable parameter position closed-loop control; when the angle mechanism runs in the positive direction, adopting the speed control first and then position closed-loop control or direct position closed-loop control mode according to the displacement difference of the upper and lower oil cylinders; switching the control system to the fine adjustment mode and judging whether the angle mechanism is in place. The application can improve the stability of the wind tunnel angle mechanism running in different directions and angle intervals by implementing segmented self-adaptive variable parameter position closed-loop control when the angle mechanism runs in the negative direction and by adopting the speed control first and then position closed-loop control or direct position closed-loop control mode when the angle mechanism runs in the positive direction.

Description

Technical Field

[0001] This invention belongs to the field of wind tunnel testing technology, and specifically relates to a model attitude mechanism control method adapted to large overload of dual-cylinder linkage. Background Technology

[0002] Wind tunnels are a primary means of conducting ground-based aerodynamic research on aerospace vehicles. They play a crucial role in aerodynamic database construction, overall aircraft and component layout optimization, test intensity verification, and inlet performance simulation. When aircraft models undergo aerodynamic testing in wind tunnels, not only does the wind tunnel provide high-precision flow field control, but it also places high demands on the stability and control accuracy of the model's attitude mechanism. A certain wind tunnel's full-model test section is a key piece of equipment for ground-based aerodynamic simulation of aerospace vehicles. Its model support typically employs tail, belly, or back supports, using a bevel mechanism to achieve stable operation and precise positioning of the model's angle-of-attack mechanism. During operation, the upper / lower hydraulic cylinders generate torque through a push-pull mechanism, jointly driving the bevel mechanism to rotate around its rotation center along a circular arc guide rail in the direction of gravity. However, this mechanism is characterized by its large structural size, wide operating angle range, large aerodynamic load fluctuations, and strong overload characteristics. When the mechanism is running in the forward direction, the load force is transformed into power, forming a large overload, which causes the hydraulic cylinder to be driven. If the oil supply is insufficient, a vacuum may occur in the hydraulic cylinder, which will cause the angle-of-attack mechanism to run at different speeds, vibrate and crawl, thus affecting the accuracy of data acquisition, and even posing a safety risk of hydraulic cylinder damage. Summary of the Invention

[0003] The purpose of this invention is to provide a model attitude mechanism control method adapted to the above-mentioned problems, which is expected to improve the problems of crawling, swaying and insufficient positioning accuracy of the wind tunnel angle of attack mechanism under large load and large overload conditions.

[0004] The technical solution adopted in this invention is as follows: A model attitude mechanism control method adapted to dual-cylinder linkage with large overload, used to control the model attitude, thereby improving the stability of the angle of attack mechanism operation. The control method includes the following steps: Step S100: Determine the running direction of the angle of attack mechanism and the positive and negative directions of the upper and lower hydraulic cylinders; Step S200: Calculate the displacement difference between the upper and lower cylinders corresponding to the target angle and the current angle; Step S300: Based on the running direction of the angle of attack mechanism, a differentiated control strategy is adopted; when the angle of attack mechanism is running in the negative direction, segmented adaptive variable parameter position closed-loop control is implemented; when running in the positive direction, based on the magnitude of the displacement difference between the upper and lower cylinders, either speed control followed by position closed-loop control or direct position closed-loop control is adopted. Step S400: Switch the control system to fine-tuning mode and determine whether the angle of attack is in place.

[0005] Furthermore, in step S100, the upper cylinder is set as the main drive shaft and the lower cylinder as the follower shaft. The upper and lower cylinders perform reciprocating linear telescopic motion in the horizontal direction and, together with their drive mechanism, rotate around the rotation center in the direction of gravity. The angle of attack mechanism is set to move downward around the rotation center as positive operation and vice versa. When the angle-of-attack mechanism is running in the forward direction, the upper and lower cylinders extend or retract in the horizontal direction. That is, the center position of the upper and lower cylinders when they extend or retract is used as the dividing point. The direction of extension of the upper cylinder and the direction of retraction of the lower cylinder are defined as positive, and the direction of movement of the upper and lower cylinders is defined as negative.

[0006] Furthermore, in step S200, the displacement difference between the upper and lower cylinders is calculated based on the target angle and the current angle. , :

[0007]

[0008] in, and These are the displacement values ​​of the upper and lower hydraulic cylinders at the target angle, respectively. and These are the displacement values ​​of the upper and lower cylinders at the current angle, respectively. .

[0009] Furthermore, the displacement values ​​of the upper and lower cylinders are absolute values, and the target angle and the current angle are relative values ​​based on the zero point of the model; when the model attitude is zeroed, the current angle is collected as zero, and the conversion between angle and displacement is based on trigonometric function relationships.

[0010] Furthermore, in step S300, when the angle-of-attack mechanism is running in the negative direction, segmented adaptive variable parameter position closed-loop control is implemented to control the displacement difference of the upper cylinder. As input, the preset threshold is divided into three control intervals, and the corresponding proportional coefficient is automatically loaded for each interval:

[0011] in, , , This is the proportionality coefficient. , This is the displacement segment threshold, in mm; When the angle-of-attack mechanism is running in the forward direction, the displacement difference of the upper cylinder will be... Location closed-loop threshold If a comparison is made, If so, then position closed-loop control is performed directly. Therefore, a speed control followed by a position closed-loop control is adopted.

[0012] Furthermore, step S300 includes two stages: speed control and position closed-loop control. During the speed control phase, the total displacement consists of three parts: acceleration, constant speed, and deceleration.

[0013] in, For acceleration, For acceleration time, For uniform velocity, For uniform velocity time, To decelerate, For deceleration time; During the acceleration phase, the angle-of-attack mechanism starts from rest and accelerates. Run to target speed During the constant speed phase, maintain the target speed. Continuous operation; during the deceleration phase, with reduced speed. Reduced to switching speed ; During the position closed-loop control phase, when deceleration Reduced to switching speed At this time, the speed control switches to position closed-loop control.

[0014] Furthermore, in step S400, the displacement difference of the upper cylinder is... With precision threshold When comparing, At that time, the control system switches to fine-tuning mode and delays. After a certain time, the angle-of-attack mechanism is determined to be in position; the control deviation is corrected through an integral iterative algorithm to complete the precise positioning and braking of the angle-of-attack mechanism.

[0015] Furthermore, the integral iterative algorithm is expressed as follows:

[0016] in, For integration, For integral gain, To control deviation, It is a natural number.

[0017] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. Based on the operating direction of the angle of attack mechanism, the present invention adopts a differentiated control strategy. When running in the negative direction, it implements segmented adaptive variable parameter position closed-loop control, and when running in the positive direction, it adopts a control method of first controlling the speed and then the position closed loop or directly controlling the position closed loop. This can improve the stability of the wind tunnel angle of attack mechanism when running in different directions and angle ranges.

[0018] 2. This invention improves the positioning accuracy of the angle-of-attack mechanism by correcting parameters through an integral iterative algorithm during the fine-tuning of the control system. Attached Figure Description

[0019] Figure 1 This is a flowchart of the method of the present invention; Figure 2 This is a schematic diagram of the angle-of-attack mechanism of the present invention; Figure 3 This is a schematic diagram of the forward operation control principle curve of the present invention; Reference numerals in the attached diagram: 1. Curved blade; 2. Upper hydraulic cylinder; 3. Lower hydraulic cylinder; 4. Hydraulic cylinder support; 5. Arc guide rail; 6. Positioning wheel. Detailed Implementation

[0020] The present invention will now be described in detail with reference to the accompanying drawings.

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0022] Considering the operational characteristics of the curved blade mechanism, this invention proposes a model attitude mechanism control method adapted to large overload conditions with dual-cylinder linkage. During the negative rotation of the curved blade mechanism, segmented adaptive variable parameter position closed-loop control is implemented to overcome resistance, suppress creeping and jerking, and improve response speed. During the positive rotation, if the stroke is large, speed control followed by position closed-loop control is used to constrain overshoot and vibration caused by overload. For short strokes, position closed-loop control is used to ensure smooth operation. This directional, differentiated control strategy effectively solves problems such as unstable operating speed and vibration in traditional control systems, significantly improving the smoothness and positioning performance of the mechanism's operation, while eliminating the potential for vacuum in the cylinders, ensuring the safety and reliability of the equipment. Example 1 like Figure 1 As shown, one embodiment of the present invention is a model attitude mechanism control method adapted to a dual-cylinder linkage with a large overload, the method comprising the following steps: Step S100: Determine the running direction of the angle of attack mechanism and the positive and negative directions of the upper and lower hydraulic cylinders; The upper hydraulic cylinder is set as the main drive shaft and the lower hydraulic cylinder as the follower shaft. The upper and lower hydraulic cylinders perform reciprocating linear telescopic motion in the horizontal direction, and together with their drive mechanism, they rotate around the rotation center in the direction of gravity. The angle of attack mechanism is set to move downward around the rotation center as positive operation and upward as negative operation. When the angle-of-attack mechanism is running in the forward direction, the upper and lower cylinders extend or retract in the horizontal direction. That is, the center position of the upper and lower cylinders when they extend or retract is used as the dividing point. The direction of extension of the upper cylinder and the direction of retraction of the lower cylinder are defined as positive, and the direction of movement of the upper and lower cylinders is defined as negative.

[0023] Step S200: Calculate the displacement difference between the upper and lower cylinders corresponding to the target angle and the current angle; Calculate the displacement difference between the upper and lower cylinders based on the target angle and the current angle. , :

[0024]

[0025] in, and These are the displacement values ​​of the upper and lower hydraulic cylinders at the target angle, respectively. and These are the displacement values ​​of the upper and lower cylinders at the current angle, respectively. .

[0026] The displacement values ​​of the upper and lower cylinders are absolute values, and the target angle and the current angle are relative values ​​based on the zero point of the model. When the model attitude is zeroed, the current angle is collected as zero, and the conversion between angle and displacement is based on trigonometric function relationships.

[0027] Step S300: Based on the running direction of the angle of attack mechanism, a differentiated control strategy is adopted; when the angle of attack mechanism is running in the negative direction, segmented adaptive variable parameter position closed-loop control is implemented; when running in the positive direction, based on the magnitude of the displacement difference between the upper and lower cylinders, either speed control followed by position closed-loop control or direct position closed-loop control is adopted. When the angle-of-attack mechanism is running in the negative direction, segmented adaptive variable parameter position closed-loop control is implemented to control the displacement difference of the upper cylinder. As input, the preset threshold is divided into three control intervals, and the corresponding proportional coefficient is automatically loaded for each interval:

[0028] in, , , This is the proportionality coefficient. , This is the displacement segment threshold, in mm; When the angle-of-attack mechanism is running in the forward direction, the displacement difference of the upper cylinder will be... Location closed-loop threshold If a comparison is made, If so, then position closed-loop control is performed directly. Therefore, a speed control followed by a position closed-loop control is adopted.

[0029] Step S300 includes two stages: speed control and position closed-loop control. During the speed control phase, a trapezoidal speed curve is generated (e.g., Figure 3 As shown), the total displacement includes three parts: acceleration, constant velocity, and deceleration.

[0030] in, For acceleration, For acceleration time, For uniform velocity, For uniform velocity time, To decelerate, For deceleration time; During the acceleration phase, the angle-of-attack mechanism starts from rest and accelerates. Run to target speed During the constant speed phase, maintain the target speed. Continuous operation; during the deceleration phase, with reduced speed. Reduced to switching speed ; During the position closed-loop control phase, when deceleration Reduced to switching speed At this time, the speed control switches to position closed-loop control.

[0031] By setting acceleration, deceleration, target speed, switching speed, position closed-loop threshold, and trapezoidal speed curve, the continuous process in speed control mode can be calculated.

[0032] Step S400: Switch the control system to fine-tuning mode and determine whether the angle of attack is in place.

[0033] Displacement difference of the upper cylinder With precision threshold When comparing, At that time, the control system switches to fine-tuning mode and delays. After a certain time, the angle-of-attack mechanism is determined to be in position; the control deviation is corrected through an integral iterative algorithm to complete the precise positioning and braking of the angle-of-attack mechanism.

[0034] The integral iterative algorithm is expressed as follows:

[0035] in, For integration, For integral gain, To control deviation, It is a natural number.

[0036] This embodiment adopts a differentiated control strategy based on the operating direction of the angle of attack mechanism. When running in the negative direction, it implements segmented adaptive variable parameter position closed-loop control, and when running in the positive direction, it adopts a control method of first controlling the speed and then the position closed loop or directly controlling the position closed loop. This can improve the stability of the wind tunnel angle of attack mechanism when running in different directions and angle ranges.

[0037] Example 2 like Figures 2-3 As shown in the figure, the angle-of-attack mechanism of the transient transonic wind tunnel full-model test section in this embodiment is used to achieve stable operation and precise positioning of the aircraft model at the angle of attack during the test. A schematic diagram of its angle-of-attack mechanism structure is shown below. Figure 2 As shown. The upper cylinder 2 and the lower cylinder 3 are connected to the arc guide rail 5 through the cylinder support 4. The two ends of the curved blade 1 are connected to the upper cylinder 2 and the lower cylinder 3 through the arc guide rail 5 respectively. The positioning wheel 6 is used to position the upper cylinder 2 and the lower cylinder 3.

[0038] The angle-of-attack mechanism has an angle-of-attack control range of ±22 degrees. The maximum stroke range of both the upper cylinder 2 and the lower cylinder 3 is 1800mm. The upper cylinder 2 and lower cylinder 3 reciprocate linearly in the horizontal direction, generating a push-pull torque that jointly drives the angle-of-attack mechanism to rotate along the arc guide rail 5 around the rotation center in the direction of gravity, thus achieving precise control of the angle-of-attack mechanism. However, when the angle-of-attack mechanism is running in the forward direction, because the load and the torque generated by the cylinders are in the same direction, the load becomes the driving force, forming a large overload, causing the cylinders to be dragged. If the lubrication is insufficient, a vacuum may occur in the cylinders, leading to inconsistent operating speeds, vibration, and creeping phenomena in the angle-of-attack mechanism, thus affecting the accuracy of data acquisition and even posing a safety risk of cylinder damage.

[0039] To obtain more accurate aerodynamic test data and eliminate the potential for cylinder damage under large overload conditions, the angle-of-attack mechanism is required to have stable operation and precise positioning capabilities. Based on this requirement, this embodiment proposes a model attitude mechanism control method suitable for dual-cylinder linkage under large overload conditions: The upper cylinder 2 is set as the main drive shaft and the lower cylinder 3 as the follower shaft. The upper cylinder 2 and the lower cylinder 3 perform reciprocating linear telescopic motion in the horizontal direction, and their drive mechanism rotates around the rotation center in the direction of gravity. The angle of attack mechanism is set to move downward around the rotation center as positive operation and downward as negative operation. When the angle of attack mechanism moves in the positive direction, the upper cylinder 2 and the lower cylinder 3 extend or retract in the horizontal direction. That is, the center position of the upper cylinder 2 and the lower cylinder 3 when they extend or retract is used as the dividing point. The direction of extension of the upper cylinder 2 and the direction of retraction of the lower cylinder 3 are defined as positive, and the direction of movement of the upper cylinder 2 and the lower cylinder 3 is defined as negative. The stroke range of the upper cylinder 2 and the lower cylinder 3 is -900mm to 900mm. Calculate the displacement difference between upper cylinder 2 and lower cylinder 3 based on the target angle and the current angle. , :

[0040]

[0041] in, and These are the displacement values ​​of the upper hydraulic cylinder 2 and the lower hydraulic cylinder 3 at the target angle, respectively. and These are the displacement values ​​of the upper cylinder 2 and the lower cylinder 3 at the current angle, respectively. .

[0042] The displacement values ​​of upper cylinder 2 and lower cylinder 3 are absolute values, and the target angle and current angle are relative values ​​based on the model's zero point. When zeroing the model's attitude, the current angle is collected as zero. The conversion between angle and displacement is based on trigonometric function relationships, and the conversion relationship is as follows:

[0043] in, The current model pose angle, , These are the displacement values ​​of the upper hydraulic cylinder 2 and the lower hydraulic cylinder 3 when the angle of attack mechanism is zero. If the current model angle is zero, then... , The value assigned to , .

[0044] like Figure 3 As shown, the black line represents the velocity curve of the motion as a function of displacement; the black dashed line represents the selected range values ​​of 0%, 50%, and 100% deceleration; the blue dashed line represents the boundary lines of each stage; the horizontal axis S represents displacement, and the vertical axis V represents velocity; when the angle-of-attack mechanism operates in the negative direction, segmented adaptive variable parameter position closed-loop control is implemented to control the displacement difference of the upper cylinder. As input, the preset threshold is divided into three control intervals, and the corresponding proportional coefficient is automatically loaded for each interval:

[0045] in, , , , , The unit is mm; When the angle-of-attack mechanism is running in the forward direction, the displacement difference of the upper cylinder will be... Location closed-loop threshold If a comparison is made, If so, then position closed-loop control is performed directly. Therefore, a speed control followed by a position closed-loop control is adopted.

[0046] During the speed control phases (S1, S2, S3), the total displacement comprises three parts: acceleration, constant speed, and deceleration.

[0047] Wherein, S1 is the displacement value during the acceleration phase, S2 is the displacement value during the constant velocity phase, and S3 is the displacement value during the deceleration phase; the acceleration and deceleration settings are adjusted according to the stiffness, load, and performance requirements of the angle-of-attack mechanism system, and the deceleration characteristic curve is selected within the range of 0~100%. In this embodiment, , For acceleration time, , For uniform velocity time, , For deceleration time, , The diameter is 15mm, and the deceleration characteristic curve is selected as 50%. During the acceleration phase, the angle-of-attack mechanism starts from rest and accelerates. Run to target speed During the constant speed phase, maintain the target speed. Continuous operation; during the deceleration phase, with reduced speed. Reduced to switching speed ; During the position closed-loop control phase, when deceleration Reduced to switching speed At this time, the speed control switches to position closed-loop control.

[0048] Displacement difference of the upper cylinder With precision threshold When comparing, At that time, the control system switches to fine-tuning mode and delays. After a certain time, the angle-of-attack mechanism is determined to be in position; the control deviation is corrected through an integral iterative algorithm to complete the precise positioning and braking of the angle-of-attack mechanism. The value range is 5mm-10mm. The value range is 200ms-500ms.

[0049] The integral iterative algorithm is expressed as follows:

[0050] in, For integration, For integral gain, To control deviation, It is 500.

[0051] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for controlling the attitude mechanism of a model adapted to a large overload with dual-cylinder linkage, characterized in that, The control method includes the following steps: Step S100: Determine the running direction of the angle of attack mechanism and the positive and negative directions of the upper and lower hydraulic cylinders; Step S200: Calculate the displacement difference between the upper and lower cylinders corresponding to the target angle and the current angle; Step S300: Based on the running direction of the angle of attack mechanism, a differentiated control strategy is adopted; when the angle of attack mechanism is running in the negative direction, segmented adaptive variable parameter position closed-loop control is implemented; when running in the positive direction, based on the magnitude of the displacement difference between the upper and lower cylinders, either speed control followed by position closed-loop control or direct position closed-loop control is adopted. In step S300, when the angle of attack mechanism is running in the negative direction, segmented adaptive variable parameter position closed-loop control is implemented to control the displacement difference of the upper cylinder. As input, the preset threshold is divided into three control intervals, and the corresponding proportional coefficient is automatically loaded for each interval: in, , , This is the proportionality coefficient. , This is the displacement segmentation threshold, in mm; When the angle-of-attack mechanism is running in the forward direction, the displacement difference of the upper cylinder will be... Location closed-loop threshold If a comparison is made, If so, then position closed-loop control is performed directly. Then, speed control followed by position closed-loop control is adopted; Step S300 includes two stages: speed control and position closed-loop control. During the speed control phase, the total displacement consists of three parts: acceleration, constant speed, and deceleration. in, For acceleration, For acceleration time, For uniform velocity, For uniform velocity time, To decelerate, For deceleration time; During the acceleration phase, the angle-of-attack mechanism starts from rest and accelerates. Run to target speed During the constant speed phase, maintain the target speed. Continuous operation; during the deceleration phase, with reduced speed. Reduced to switching speed ; During the position closed-loop control phase, when deceleration Reduced to switching speed At this time, the speed control switches to position closed-loop control; Step S400: Switch the control system to fine-tuning mode and determine whether the angle of attack is in place.

2. The model attitude mechanism control method adapted to a dual-cylinder linkage with a large overload according to claim 1, characterized in that, In step S100, the upper cylinder is set as the main drive shaft and the lower cylinder as the follower shaft. The upper and lower cylinders perform reciprocating linear telescopic motion in the horizontal direction and, together with their drive mechanism, rotate around the rotation center in the direction of gravity. The angle of attack mechanism is set to move downward around the rotation center as positive operation and vice versa. When the angle-of-attack mechanism is running in the forward direction, the upper and lower cylinders extend or retract in the horizontal direction. That is, the center position of the upper and lower cylinders when they extend or retract is used as the dividing point. The direction of extension of the upper cylinder and the direction of retraction of the lower cylinder are defined as positive, and the direction of movement of the upper and lower cylinders is defined as negative.

3. The model attitude mechanism control method adapted to a dual-cylinder linkage with a large overload according to claim 1, characterized in that, Step S200: Calculate the displacement difference between the upper and lower cylinders based on the target angle and the current angle. , : in, and These are the displacement values ​​of the upper and lower hydraulic cylinders at the target angle, respectively. and These are the displacement values ​​of the upper and lower cylinders at the current angle, respectively. .

4. The model attitude mechanism control method adapted to a dual-cylinder linkage with a large overload according to claim 3, characterized in that, The displacement values ​​of the upper and lower cylinders are absolute values, and the target angle and the current angle are relative values ​​based on the zero point of the model. When the model attitude is zeroed, the current angle is collected as zero, and the conversion between angle and displacement is based on trigonometric function relationships.

5. A model attitude mechanism control method adapted to a dual-cylinder linkage with a large overload according to claim 4, characterized in that, In step S400, the displacement difference of the upper cylinder is... With precision threshold When comparing, At that time, the control system switches to fine-tuning mode and delays. After a certain time, the angle-of-attack mechanism is determined to be in position; the control deviation is corrected through an integral iterative algorithm to complete the precise positioning and braking of the angle-of-attack mechanism.

6. The model attitude mechanism control method adapted to a dual-cylinder linkage with a large overload according to claim 5, characterized in that, The integral iterative algorithm is expressed as follows: in, For integration, For integral gain, To control deviation, It is a natural number.

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