Compensation method for synchronous control of multiple hydraulic cylinders

Abstract

The invention discloses a compensation method for synchronous control of multiple hydraulic cylinders, and belongs to the technical field of hydraulic control. Aiming at the problem of synchronous compensation systematic deviation caused by neglecting deformation of a structure field of a controlled object in the prior art, the invention provides a dynamic compensation method based on a deformation shearing force weight. The core of the method comprises the steps that displacement data yi of all hydraulic cylinders and deformation shearing force data FSi at all jacking points are obtained in real time, the displacement compensation weight rho i of all the hydraulic cylinders is calculated, and compensation displacement yci is dynamically distributed in combination with the current maximum displacement difference delta Ymax; by means of the strain energy theory, shear force is used as characterization of energy accumulation, the displacement compensation difficulty degree of each jacking point is quantified, and self-adaptive matching of the compensation amount and the structural rigidity is achieved; the method effectively reduces local overcompensation or undercompensation, improves synchronization precision, and is especially suitable for working conditions having requirements for stress state changes of a controlled object.

Description

Technical Field

[0001] The present invention belongs to the field of hydraulic control, and relates to a compensation method for synchronous control of multiple hydraulic cylinders, specifically a dynamic compensation method based on the deformation of the vehicle structure field. Background Art

[0002] The synchronous lifting application scenarios of multiple hydraulic cylinders are increasing, especially in scenarios where the synchronization requirement is higher than the tracking accuracy requirement. Such as the case of the synchronous movement of the hydraulic cylinders of the tilting cooling bed of the continuous casting machine cited in the publication number CN101672311A; in addition, before the aircraft undergoes the passenger-to-freighter conversion project operation, the whole fuselage of the aircraft needs to be jacked up. The greater the displacement error between the jacking points, the greater the change in the stress state of the modified part of the aircraft, which directly affects the modification quality. In the multi-hydraulic cylinder synchronous control system, the existing technology (such as the publication number CN110107552A) corrects the displacement compensation amount of other hydraulic cylinders based on the displacement data of each hydraulic cylinder collected in real time with the displacement of any one hydraulic cylinder as the reference. Although the accuracy is improved, there are still the following problems: (1) Systematic deviation: The existing compensation method only generates a compensation signal based on the displacement difference, without considering the dynamic response of the structure field of the controlled object during force deformation, resulting in a mismatch between the compensation amount and the actual demand. (2) Uneven energy distribution: Due to the stiffness difference of different jacking points, the energy required for the same displacement compensation amount is different. The traditional method does not quantify the compensation difficulty of each jacking point, which is likely to cause local over-compensation or under-compensation. Summary of the Invention

[0003] The present invention aims to solve the problem of insufficient compensation accuracy caused by ignoring the deformation of the structure field in the existing technology, and proposes a compensation method for synchronous control of multiple hydraulic cylinders based on the compensation weight of deformation shear displacement. The core innovations include: (1) Allocating the compensation amount according to the shear force weight: Determine the weight according to the deformation shear force multiple relationship at the asynchronous jacking points of the controlled object, and dynamically generate the compensation displacement in combination with the maximum synchronous error amount to quantify the compensation difficulty of each jacking point. (2) Integrating the dynamic response of the structure field: Through the strain energy theory, use the shear force as the representation of energy accumulation to achieve the adaptive matching of the compensation amount and the structural stiffness. (3) Obtaining multi-modal shear forces: Support three sources of shear force data, including physical measurement, Adams real-time simulation calculation, and prediction model, to improve the applicability of the method.

[0004] A compensation method for synchronous control of multiple hydraulic cylinders includes the following steps: Data acquisition: Real-time obtain the displacement data y of each hydraulic cylinder i and the deformation shear force data F at each jacking point Si ; Weight calculation: Calculate the displacement compensation weight of each hydraulic cylinder by the analysis and control unit: ; Combined with the current maximum displacement difference ΔYmax , generate the compensation displacement of each hydraulic cylinder: ; Signal conversion: Convert the compensation displacement into a proportional valve control signal to adjust the flow rate of the hydraulic cylinder.

[0005] Among them, y i is the displacement of each hydraulic cylinder; F Si is the deformation shear force at each jacking point; ρ i is the displacement compensation weight of each hydraulic cylinder; ΔY max is the current maximum displacement difference; y ci is the displacement compensation amount.

[0006] Furthermore, the deformation shear force data at each jacking point is obtained in real time through any one of the following three methods: (1) Measuring with a shear stress strain gauge, (2) Establishing a simplified physical model of the control system in Adams, and calculating the jacking point shear force through online kinematic simulation based on the measured displacement data of each hydraulic cylinder, (3) Inputting different hydraulic cylinder displacement conditions into the physical model established in Adams to calculate the corresponding jacking point shear force, and establishing a displacement-shear force prediction model to predict the shear force.

[0007] Furthermore, in the definition of calculating the displacement compensation weight of each hydraulic cylinder, the weight refers to the algebraic value of the shear force at the jacking point of the corresponding hydraulic cylinder accounting for the sum of the absolute values of the shear forces at the jacking points of all hydraulic cylinders.

[0008] Even further, the displacement compensation weight of the hydraulic cylinder is an algebraic value, the sum of the absolute values of the displacement compensation weights of each hydraulic cylinder is 1, and the algebraic sum is 0 (satisfying the shear force balance equation).

[0009] Even further, the positive and negative signs of the compensation displacement of the hydraulic cylinder are determined by the positive and negative signs of the shear force at the corresponding jacking point, the sum of the absolute values of the displacement compensation amounts of each hydraulic cylinder is the maximum displacement difference value, and the algebraic sum is 0 (determined by the algebraic sum of the compensation weights being 0).

[0010] Furthermore, when a multi-hydraulic cylinder jacking vehicle is used, due to the asynchronous operation of the hydraulic cylinders, the vehicle is deformed, and a deformation shear force is generated at the jacking point where the hydraulic cylinder is connected to the vehicle; the displacement compensation strategy of the hydraulic cylinder is set according to the shear force situation, which is different from the current compensation strategy directly based on the displacement difference value.

[0011] Compared with the prior art, the beneficial effects of the present invention are: Utilize the strain energy theory, regard the shear force as the characterization of energy accumulation, quantify the difficulty degree of compensation at each jacking point, and realize the adaptive matching of the compensation amount and the structural stiffness.

[0012] This method effectively reduces local over-compensation or under-compensation and improves synchronization accuracy.

[0013] Under the same displacement synchronization accuracy, this method can effectively improve the fatigue strain condition of the vehicle, increase the service life of the vehicle, and is especially suitable for working conditions with requirements for the stress state change of the controlled object. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0015] Figure 1 It is a schematic diagram of the working steps of the present invention, Figure 2 It is a schematic diagram of the strain energy theory, Figure 3 It is the displacement change amount and shear force condition of each jacking point of the vehicle in the embodiment, Figure 4 It is the evolution of the strain energy of each jacking point of the vehicle in this embodiment, Figure 5 It is a schematic diagram of the strain energy evolution micro-element. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0016] The following will clearly and completely describe the technical solutions of the present invention in combination with the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0017] The prior art (such as publication number CN110107552A) collects the displacement data of each hydraulic cylinder in real time, takes the displacement of any hydraulic cylinder as a reference, and corrects the displacement compensation amount of other hydraulic cylinders. Although the accuracy is improved, there are still the following problems: (1) Systematic deviation: The existing compensation method only generates a compensation signal based on the displacement difference, without considering the dynamic response of the structural field of the controlled object during force deformation, resulting in a mismatch between the compensation amount and the actual demand. (2) Uneven energy distribution: Due to the stiffness difference of different jacking points, the energy required for the same displacement compensation amount is different. The traditional method does not quantify the compensation difficulty of each jacking point, and it is easy to cause local over-compensation or under-compensation.

[0018] The present invention aims to solve the problem of insufficient compensation accuracy caused by ignoring the structural field deformation in the prior art, and proposes a multi-hydraulic cylinder synchronous control compensation method based on the compensation weight of deformed shear force and displacement. The core innovations include: (1) Allocating the compensation amount according to the shear force weight: determining the weight based on the deformation shear force multiple relationship at the asynchronous jacking points of the controlled object, dynamically generating the compensation displacement in combination with the maximum synchronous error amount, and quantifying the compensation difficulty degree of each jacking point. (2) Integrating the dynamic response of the structural field: Through the strain energy theory ( , such as Figure 2 shown), taking the shear force as the characterization of energy accumulation, and realizing the adaptive matching of the compensation amount and the structural stiffness. (3) Obtaining multi-modal shear forces: Supporting three sources of shear force data, including physical measurement, Adams real-time simulation calculation and prediction model, to improve the applicability of the method.

[0019] Figure 2 In V εi is the strain energy stored at each jacking point, F Si is the deformed shear force at each jacking point, Δ i is the deformed displacement amount along the jacking direction from the position where the shear force is zero to the current position.

[0020] A compensation method for multi-hydraulic cylinder synchronous control includes the following steps: Data acquisition: Real-time obtain the displacement data y i of each hydraulic cylinder and the deformed shear force data F Si at each jacking point; Weight calculation: The analysis control unit calculates the displacement compensation weight of each hydraulic cylinder: (1) Combined with the current maximum displacement difference ΔY max , generate the compensation displacement of each hydraulic cylinder: (2) Signal conversion: Convert the compensation displacement into a proportional valve control signal to adjust the flow rate of the hydraulic cylinder.

[0021] Among them, y i is the displacement of each hydraulic cylinder; F Si is the deformed shear force at each jacking point; ρ i is the displacement compensation weight of each hydraulic cylinder; ΔY max is the current maximum displacement difference; y ci is the displacement compensation amount.

[0022] Illustrate this embodiment by way of example. Suppose there are 4 hydraulic cylinders for lifting a vehicle, and the corresponding displacement data (unit: mm) are measured as 101, 100, 102, 103 respectively, and the corresponding shear force data at the jacking points (unit: kN) are measured as 40.24, -91.73, 62.82, -11.32 respectively.

[0023] The displacement change and shear force of each jacking point based on the average displacement are as Figure 3 shown.

[0024] Figure 3 In y avg is the average displacement; y i is the real-time displacement of each hydraulic cylinder; Δ avgi is the displacement change of the i-th hydraulic cylinder based on the average displacement, and the calculation rule is: ; Shear force F Si Symbol definition: The direction opposite to the jacking force of the hydraulic cylinder is positive, and the same direction is negative; The strain energy stored at each jacking point is as Figure 4 shown.

[0025] Figure 4 In The definition of the strain energy evolution process: Δ avgi and F Si having the same sign means storing strain energy, such as jacking points 3 and 2 in the first and third quadrants; Δ avgi and F Si having opposite signs means releasing strain energy, such as jacking points 1 and 4 in the second and fourth quadrants.

[0026] The reason for selecting the shear force weight distribution compensation amount is to consider the microelement of the strain energy evolution process, as Figure 5 shown.

[0027] Figure 5 In d V εi is the strain energy evolution microelement, and its magnitude is: , starting from the perspective of energy, to achieve the adaptive matching of the compensation amount and the structural stiffness, making the compensation amount ∝ shear force.

[0028] Calculate the displacement compensation weights of each hydraulic cylinder. Through Equation 1, it is calculated that ρ i are 0.195, -0.445, 0.305, -0.055 respectively (the sum of the absolute values is 1, and the algebraic sum is 0).

[0029] The current maximum synchronization error, .

[0030] Generate the compensation displacement of each hydraulic cylinder. Through Equation 2, it is calculated that y ci are 0.585 mm, -1.335 mm, 0.915 mm, and -0.165 mm respectively.

[0031] Convert the compensation displacement into a proportional valve control signal to adjust the flow rate of the hydraulic cylinder.

[0032] The working principle of the present invention: The displacement data of each hydraulic cylinder and the deformation shear force data at each jacking point are obtained in real time through the state detection device and sent to the analysis and control unit in real time.

[0033] The analysis and control unit calculates the displacement compensation weight of each hydraulic cylinder according to the shear force at each jacking point, and generates a displacement compensation amount in combination with the current maximum displacement difference.

[0034] The analysis and control unit synchronously adjusts each hydraulic cylinder according to the displacement compensation amount to achieve the purpose of multi-cylinder synchronization.

[0035] The above embodiments are only used to illustrate the technical method of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical method of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical method of the present invention.

Claims

1. A compensation method for synchronous control of multiple hydraulic cylinders, characterized in that: The compensation method includes the following steps: Obtain the displacement data y of each hydraulic cylinder in real time i and the deformation shear force data F at each jacking point Si ; The analysis and control unit calculates the displacement compensation weights of each hydraulic cylinder: ; Combine the current maximum displacement difference ΔY max , and generate the compensation displacement of each hydraulic cylinder: ; Convert the compensation displacement into a proportional valve control signal to adjust the flow rate of the hydraulic cylinder, wherein, y i is the displacement of each hydraulic cylinder; F Si is the deformation shear force at each jacking point; ρ i is the displacement compensation weight of each hydraulic cylinder; ΔY max is the current maximum displacement difference; y ci is the displacement compensation amount.

2. The compensation method for synchronous control of multiple hydraulic cylinders according to claim 1, wherein in the definition of calculating the displacement compensation weight of each hydraulic cylinder, the weight refers to the algebraic value of the shear force at the jacking point of the corresponding hydraulic cylinder accounting for the sum of the absolute values of the shear forces at the jacking points of all hydraulic cylinders.

3. A compensation method for synchronous control of multiple hydraulic cylinders according to claim 2, characterized in that, The displacement compensation weight of the hydraulic cylinder is an algebraic value, the sum of the absolute values of the displacement compensation weights of each hydraulic cylinder is 1, and the algebraic sum is 0.

4. A compensation method for synchronous control of multiple hydraulic cylinders according to claim 1, characterized in that, The positive or negative sign of the compensation displacement of the hydraulic cylinder is determined by the positive or negative sign of the shear force at the corresponding jacking point, the sum of the absolute values of the displacement compensation amounts of each hydraulic cylinder is the maximum displacement difference value, and the algebraic sum is 0.

5. A compensation method for synchronous control of multiple hydraulic cylinders according to claim 1, characterized in that, When a multi-hydraulic cylinder jacking vehicle is used, due to the non-synchronization of the hydraulic cylinders, the vehicle is deformed, and a deformation shear force is generated at the jacking point where the hydraulic cylinder is connected to the vehicle; the displacement data of each hydraulic cylinder and the deformation shear force data at each jacking point are obtained in real time, the displacement compensation weight of each hydraulic cylinder is calculated according to the shear force at each jacking point, the displacement compensation amount is generated in combination with the current maximum displacement difference, and each hydraulic cylinder is synchronously adjusted according to the displacement compensation amount.

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