A high-precision loading method with adaptive gap compensation function

Abstract

The application discloses a high-precision loading method with self-adaptive gap compensation function, comprising the following steps: establishing a gap error model of an electric steering servo loading system; identifying the to-be-identified hysteresis characteristic parameters in the gap error model according to the sampling values of a measured servo mechanism displacement sensor and a loading hydraulic cylinder of the electric steering servo loading system; obtaining the real value of the measured servo mechanism displacement corresponding to the displacement sampling value of the loading hydraulic cylinder based on the gap error model after identifying the hysteresis characteristic parameters; and the loading hydraulic cylinder outputs a loading force to the servo mechanism according to the real value of the servo mechanism displacement and a loading curve. The application realizes high-precision loading of the electric steering system.

Description

Technical Field

[0001] This invention belongs to the field of load loading test of electric steering systems, and relates to a high-precision loading method with adaptive gap compensation function. Background Technology

[0002] The input to the servo loading system is the displacement signal collected by the displacement sensor of the servo loading system. Due to the existence of mechanical structure gaps, the displacement signal collected by the displacement sensor of the servo loading system is inconsistent with the position signal of the control surface controlled by the servo mechanism under test, thus affecting the loading accuracy.

[0003] Currently, most servo loading systems use time as the horizontal axis input and load force as the vertical axis output for their load loading curves. Servo loading systems for surface vessels and underwater vehicles differ significantly. The input is the position of the rudder surface, and the vertical axis represents the load force corresponding to different rudder surface positions at a given speed. Therefore, the positional accuracy requirements for servo loading systems are extremely high. Current methods for backlash compensation in servo loading systems include: 1. Connecting a low-stiffness spring rod in series between the rudder actuator and the loading hydraulic cylinder. Since the spring rod is elastic and not rigid, it affects loading performance. 2. Accumulator compensation, mainly through connecting the two chambers of the servo loading hydraulic cylinder to accumulator gas. However, this method has poor compensation accuracy when subjected to composite torque loading at multiple frequencies. 3. Using two servo valves for flow compensation to actively counteract flow impacts caused by interference errors. Matching the parameters of the two servo valves using this method is difficult. 4. Connecting the two chambers of the servo loading hydraulic cylinder using an adjustable throttle orifice. This method can cause vibration at high rudder speeds, affecting loading accuracy. 5. The servo loading system uses a hydraulic cylinder identical to the main loading cylinder for directional parallel connection. This method requires the two hydraulic cylinders to have exactly the same speed, which is extremely difficult to achieve in actual work. Summary of the Invention

[0004] The purpose of this invention is to overcome the above-mentioned defects and provide a high-precision loading method with adaptive gap compensation function, which solves the technical problem of poor loading accuracy of the gap compensation method of the existing servo loading system. This invention realizes high-precision loading of the electric steering system.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] A high-precision loading method with adaptive gap compensation function includes:

[0007] A clearance error model for the electric steering servo loading system is established, which is used to represent the relationship between the displacement of the measured servo mechanism and the displacement of the loading hydraulic cylinder of the electric steering servo loading system.

[0008] The hysteresis characteristic parameters to be identified in the clearance error model are identified based on the displacement sampling values ​​of the tested servo mechanism and the displacement sampling values ​​of the loaded hydraulic cylinder.

[0009] Based on the gap error model after identifying the hysteresis characteristic parameters, the true displacement value of the measured servo mechanism corresponding to the sampled displacement value of the loaded hydraulic cylinder is obtained.

[0010] The loading hydraulic cylinder outputs a loading force to the servo mechanism under test based on the actual displacement value and loading curve of the servo mechanism under test.

[0011] Furthermore, the gap error model can be in piecewise function form or uniform function form:

[0012] The piecewise function form of the gap error model is:

[0013] Where x(t) is the input displacement at time t, i.e., the displacement of the servo mechanism under test at time t; F[x](t) and F[x](t-1) are the output displacements at times t and t-1, respectively, i.e., the displacements of the loaded hydraulic cylinder at times t and t-1; z l and z r These represent the initial and final displacements during the reversing process of the servo mechanism driving the loading hydraulic cylinder; c r b r c l b l These are the hysteresis characteristic parameters to be identified.

[0014] Furthermore, the unified functional form of the gap error model is obtained by transforming the piecewise functional form of the gap error model as follows:

[0015] S1.1 Define the state flag factor and

[0016]

[0017] in,

[0018] S1.2 The piecewise function form of the gap error model is transformed using the state flag factor to obtain a unified function form of the gap error model.

[0019] Furthermore, the gap error model in unified functional form is as follows:

[0020]

[0021] Furthermore, methods for online identification of undetermined parameters in the gap error model include:

[0022] S2.1 Define the data vector h b(t) and the hysteresis characteristic parameter vector θ to be identified b :

[0023]

[0024] θ b =[c l c l b l c r c r b r ];

[0025] S2.2 Establish based on h b (t) and θ b The identification model:

[0026]

[0027] Where K(k) is the gain vector, P(k) is the observation error covariance sequence, k represents the k-th sampling, k takes integer values ​​greater than or equal to 0, I is a matrix of all 1s, and Y... b (k) is the difference between F[x](k) and F[x](k-1) at the k-th sampling;

[0028] S2.3 Iterate using the identification model to obtain the optimal hysteresis characteristic parameter vector that meets the error accuracy requirements.

[0029] Furthermore, the error accuracy is calculated according to the following formula:

[0030]

[0031] When β≤Δβ, the error accuracy requirement is met, where Δβ represents the error accuracy requirement.

[0032] Furthermore, in step S2.3, the method for obtaining the optimal hysteresis characteristic parameter vector that satisfies the accuracy error through iteration using the identification model includes:

[0033] S2.3.1 At the 0th sampling time, i.e., the initial time, set P(0);

[0034] Obtain x(0), and then obtain h based on x(0). b (0);

[0035] S2.3.2 Obtain x(k) and Y during the k-th sampling. b (k), h is obtained from x(k). b (k), according to h b (k), Y b (k) and the (k-1)th sampling P(k-1),hb (k-1) yields P(k) at the kth sampling time. k = 1, 2, 3...; where x(k) is x(t) at the k-th sampling, and x(k) and Y... b (k) are all sampled values;

[0036] S2.3.3 According to Y b (k), h b (k) Once β is obtained, determine whether β meets the error accuracy requirements;

[0037] When the error accuracy requirement is met, the sampling time As the optimal hysteresis characteristic parameter vector;

[0038] If the error accuracy requirement is not met, repeat step S2.3.2 in the next sampling.

[0039] Furthermore, let P(0) = 10 6 .

[0040] Furthermore, based on the gap error model after identifying the hysteresis characteristic parameters, the method for obtaining the true displacement value of the tested servo mechanism corresponding to the displacement sampling value of the loaded hydraulic cylinder is as follows: Based on the gap error model after identifying the hysteresis characteristic parameters, a gap error compensation model is established, and the displacement sampling value of the loaded hydraulic cylinder is substituted into the gap error compensation model to obtain the true displacement value of the tested servo mechanism.

[0041] Furthermore, the true value of the displacement of the tested servo mechanism is denoted as x(t). j The gap error compensation model is as follows:

[0042]

[0043] Compared with the prior art, the present invention has the following advantages:

[0044] (1) This invention creatively proposes a high-precision loading method with adaptive gap compensation function. By establishing a gap error model, the precise displacement of the servo mechanism is obtained, and high-precision loading of the electric steering system is realized.

[0045] (2) The present invention can determine the relevant parameters in the model in real time online, and adaptively update the parameters of the gap compensation model according to the latest gap error identification results and the motion characteristics of the tested servo mechanism, thereby improving the accuracy of the gap compensation model. Attached Figure Description

[0046] Figure 1 This is a schematic diagram illustrating the characteristics of the generalized gap model of the present invention;

[0047] Figure 2This is a schematic diagram of the servo loading process I of the present invention;

[0048] Figure 3 This is a schematic diagram of the servo loading process II of the present invention;

[0049] Figure 4 This is a schematic diagram of the servo loading process III of the present invention;

[0050] Figure 5 This is a flowchart of the clearance compensation process for the electric steering loading system of the present invention;

[0051] Figure 6 This is a flowchart of the loading method for the adaptive gap compensation electric steering servo loading system of the present invention;

[0052] Figure 7 This is a schematic diagram of the gap error model of the present invention.

[0053] Figure 8 This is a schematic diagram of online parameter identification for the gap error model of the present invention. Detailed Implementation

[0054] The features and advantages of the present invention will become clearer and more explicit from the following detailed description.

[0055] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments. Although various aspects of embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated otherwise.

[0056] The electric steering servo loading system is mainly used to simulate the load force borne by the steering system of surface ships and underwater vehicles. The system input x-axis of the simulated loading curve in the electric steering servo loading system represents the position of the rudder surface of the surface ship or underwater vehicle, and the system output y-axis represents the load force corresponding to different rudder surface positions at a certain speed. The electric steering servo loading system can perform conventional loading modes such as constant value, step, and triangular wave, as well as speed-specific load curve loading and inverse T-shaped load curve loading.

[0057] This invention proposes a high-precision loading method with adaptive compensation function. This method can update and identify the gap parameters in the loading system in real time. In the servo loading system, the mechanical structural components will change the structural gap due to long-term wear. This method can also identify and update the gap error in real time. It has the characteristics of speed, accuracy and adaptability, and can meet the high-precision requirements of servo loading of steering gears of surface ships and underwater vehicles.

[0058] like Figure 6The adaptive clearance compensation electric steering servo loading system loading method of the present invention includes the following steps:

[0059] Step 1: Quasi-linear modeling of the clearance in the electric steering servo loading system to obtain the clearance error model:

[0060] The hydraulic cylinder of the electric steering servo system (the servo mechanism under test) and the loading cylinder of the loading system (the loading hydraulic cylinder) are connected by screws. The hydraulic cylinder of the servo system under test pushes the loading cylinder of the loading system to move. If the mechanical structure clearance is ignored, the displacement of the hydraulic cylinder of the servo system under test is the same as the displacement of the loading cylinder of the loading system. However, in actual applications, the clearance between mechanical structures is unavoidable. Therefore, in actual applications, the displacement of the hydraulic cylinder of the servo system under test and the displacement of the loading cylinder of the loading system are different. The loading system simulates the force on the rudder surface at different positions of a surface ship and an underwater vehicle at a certain speed. However, due to the existence of mechanical structure clearance, the loading system cannot accurately simulate the load force on the rudder surface at a certain position.

[0061] like Figure 1 The diagram shows the characteristics of the generalized gap model, i.e., the gap error model.

[0062] The gap error model is as follows:

[0063]

[0064] Where x(t) is the input displacement at time t, F[x](t) and F[x](t-1) are the output displacements at times t and t-1, respectively, and c l c r The left and right slopes of the gap model, b l b r These are the left and right thresholds for the gap model, respectively. The projection is defined as the actual c. r b r c l b l All of these are hysteresis characteristic parameters to be identified;

[0065]

[0066] like Figure 2 Servo loading process I(x(t)≤z) l In process I, the servo mechanism under test drives the servo loading hydraulic cylinder to move forward. The servo mechanism under test is the driving component, and the servo loading hydraulic cylinder is the driven component. At this time, the mechanical gap between the servo mechanism under test and the transmission component of the servo loading hydraulic cylinder is filled. During process I, the servo mechanism under test drives the loading hydraulic cylinder to move forward synchronously.

[0067] like Figure 3 As shown: Servo loading process II (z l≤x(t)≤z r The tested servo mechanism drives the servo loading hydraulic cylinder to move in the positive direction and reach the reversing position. When the tested servo mechanism starts to move in the negative direction after reaching the positive reversing position, due to the mechanical error of the connecting mechanism, the tested servo mechanism will move in the negative direction, and the servo loading hydraulic cylinder will not move. When the negative movement distance of the tested servo mechanism exceeds the mechanical clearance error value, the servo loading hydraulic cylinder starts to move in the negative direction along with the tested servo mechanism. The process from the start of the reversing to the start of the servo loading hydraulic cylinder moving in the negative direction along with the tested servo mechanism is called process II. This process is the process in which the tested servo mechanism opens up the clearance distance relative to the loading hydraulic cylinder. The displacement of the loading hydraulic cylinder remains unchanged, and F[x](t) is constant.

[0068] like Figure 4 As shown: In the servo loading process III, the servo mechanism under test pulls the servo loading hydraulic cylinder to move in the negative direction. During the negative movement, there is always a mechanical clearance error between the servo mechanism under test and the servo loading hydraulic cylinder. In process III, the servo mechanism under test drives the loading hydraulic cylinder to move synchronously in the negative direction.

[0069] like Figure 7 Based on the piecewise conditions in equations (1) and (2), the hysteresis state switching factor is defined as follows:

[0070]

[0071] Here, the condition *>0 indicates that the system is in a gap state, and vice versa. The function δ changes according to the positive and negative values ​​of the condition. b The system outputs either 0 or 1 accordingly, thus indicating the transition time between system states. To describe the changes from state I(2) to II(1) and from II to III, we will... and The switching condition is defined as z r -x(t) and x(t)-z l Then the state flag factor can be rewritten as:

[0072]

[0073] Substituting equation (4) into equation (1), the hysteresis piecewise function (i.e., the gap error model in equation (1)) can be uniformly expressed as the following quasi-linear model form.

[0074]

[0075] Step 2: Online identification of clearance parameters for the electric steering servo loading system:

[0076] like Figure 8 First, define the following data vector.

[0077]

[0078] The parameter vector to be identified is

[0079] θ b =[c l c l b l c r c r b r (7)

[0080] Combining equations (5) and (7), we can obtain

[0081]

[0082] For model (8), the following identification algorithm can be used to obtain the hysteresis parameters.

[0083]

[0084] Where K(k) is the gain vector and P(k) is the observation error covariance sequence. Noise from the sensor-acquired signals is eliminated through filtering. Based on the output displacements F[x](k) and F[x](k-1) measured at two consecutive times, F[x](k)-F[x](k-1) is used as a set of input signals for identification, i.e., Y in equation (9). b (k) sequence, where t represents the continuously changing time in the above text, but not all continuous time moments are sampled. Here, k represents the time of the kth sampling. F[x](k) and F[x](k-1) are the displacements of the loaded hydraulic cylinder at the kth and k-1th sampling times, respectively. In addition, based on the quasi-linear gap model (8), combined with the input end position signal x(k) measured by the sensor, another set of input signals h required for identification can be obtained. b The required identification error accuracy for the servo loading system is as follows:

[0085]

[0086] Under the condition of ensuring continuous excitation of the above two sets of input signals, the hysteresis characteristic parameter θ b =[c l c l b l c r c r b r The iterative steps for identification are as follows:

[0087] (1) Selecting initial conditions With P(0) = 10 6 Combined with the initial position signal Y at the output end b(0) and h obtained from the initial position signal x(0) at the input terminal R (0) serves as the initial value, marking the start of the parameter identification iterative calculation;

[0088] (2) Based on the output position signal Y of the second sampling period b (1) The input position signal x(1) and each initial value are used to calculate and update P(1) using equation (9). This is recorded as the second iteration;

[0089] (3) Enter the next sampling period, repeat the previous step, and update P(2) and This process is repeated iteratively. After n iterations, when the estimation error β reaches the required accuracy, the iteration stops, and the optimal hysteresis characteristic parameters are obtained. .

[0090] Step 3: Adaptive servo mechanism backlash error compensation method:

[0091] The loading curve input of the electric steering loading system designed in this invention is the displacement of the servo mechanism under test, and the output is the loading force. Figure 5 The diagram shown is a flowchart of the clearance compensation process for the electric steering loading system.

[0092] The gap error model of the servo loading system is as follows:

[0093]

[0094] F[x](t) is the input to the servo loading system gap compensation model, x(t) j The output value of the servo loading system gap compensation model is the input value of the loading curve of the electric steering servo loading system, which is x(t) calculated by substituting the sampled value of F[x](t) into the gap error model. j .

[0095] In existing technologies, the displacement of the servo mechanism and the displacement of the loading hydraulic cylinder are measured separately. When the loading hydraulic cylinder outputs the loading force according to the loading curve, it usually assumes that the displacement of the servo mechanism is equal to the displacement of the loading hydraulic cylinder obtained by its own sampling, without considering the compensation for the gap. However, the loading curve is a loading force-servo mechanism displacement curve, which leads to inaccurate output loading force. The present invention calculates x(t) through a gap error compensation model. j To ensure accurate servo mechanism displacement, the electric steering servo loading system can realistically simulate the load force on the steering wheel at different positions and guarantee the accuracy of load force application.

[0096] The gap error compensation model is as follows:

[0097]

[0098] In the above, x(t) j F[x](t) is the output value of the servo loading system gap compensation model, and F[x](t) is the input of the servo loading system gap compensation model, which is also the feedback value of the displacement sensor of the measured servo loading hydraulic cylinder. r b l These are the left and right threshold values ​​for the identified electric steering loading system clearance error, respectively. r c is the conversion factor for the left side gap error. l z is the right-side gap error conversion coefficient. l and z r These represent the initial and final displacements, respectively, during the reversing process of the servo-driven hydraulic cylinder driven by the servo mechanism under test, i.e., z. l The displacement of the servo mechanism at the start of the reversal is due to the fact that the servo mechanism previously drove the loading hydraulic cylinder to move synchronously in the forward direction. r This refers to the displacement of the servo mechanism when the distance between it and the loading hydraulic cylinder reaches the gap width during the reverse motion of the servo mechanism. After that, the servo mechanism drives the loading hydraulic cylinder to move synchronously in the reverse direction.

[0099] The electric steering servo loading system can adaptively update the parameters of the clearance compensation model based on the latest clearance error identification results and the motion characteristics of the servo mechanism under test, thereby improving the accuracy of the clearance compensation model.

[0100] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

[0101] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A high-precision loading method with adaptive gap compensation function, characterized in that, include: A clearance error model for the electric steering servo loading system is established, which is used to represent the relationship between the displacement of the measured servo mechanism and the displacement of the loading hydraulic cylinder of the electric steering servo loading system. The hysteresis characteristic parameters to be identified in the clearance error model are identified based on the displacement sampling values ​​of the tested servo mechanism and the displacement sampling values ​​of the loaded hydraulic cylinder. Based on the gap error model after identifying the hysteresis characteristic parameters, the true displacement value of the measured servo mechanism corresponding to the sampled displacement value of the loaded hydraulic cylinder is obtained. The loading hydraulic cylinder outputs a loading force to the servo mechanism under test based on the actual displacement value and loading curve of the servo mechanism under test. The gap error model can be in piecewise function form or uniform function form: The piecewise function form of the gap error model is: in, for Input displacement at any time, i.e. The displacement of the servo mechanism being measured at all times. and They are respectively and Output displacement at all times, i.e. and The hydraulic cylinder displacement is constantly being applied. and These are the initial and final displacements during the reversing process of the loading hydraulic cylinder driven by the servo mechanism; , , , These are the hysteresis characteristic parameters to be identified; The unified functional form of the gap error model is obtained by transforming the piecewise functional form of the gap error model as follows: S1.1 Define the state flag factor and : ； in, ; S1.2 The piecewise function form of the gap error model is transformed using the state flag factor to obtain a unified function form of the gap error model; The unified functional form of the gap error model is: 。 2. The high-precision loading method with adaptive gap compensation function according to claim 1, characterized in that, Methods for online identification of undetermined parameters in the gap error model include: S2.1 Define data vector and the hysteresis characteristic parameter vector to be identified : ； S2.2 establishes a foundation based on and The identification model: in, For the gain vector, For the observation error covariance sequence, Indicates the first Second sampling, Take an integer greater than or equal to 0. It is a matrix of all ones. For the first During the next sampling, and The difference; S2.3 Iterate using the identification model to obtain the optimal hysteresis characteristic parameter vector that meets the error accuracy requirements.

3. The high-precision loading method with adaptive gap compensation function according to claim 2, characterized in that, Error accuracy is calculated using the following formula: ； when At the same time, to meet the error accuracy requirements, This indicates the required error accuracy.

4. A high-precision loading method with adaptive gap compensation function according to claim 3, characterized in that, In step S2.3, the method for obtaining the optimal hysteresis characteristic parameter vector that satisfies the accuracy error through iterative analysis using the identification model includes: S2.3.1 At the 0th sampling time, i.e., the initial time, set , ; Get ,according to get ; S2.3.2 in the During the next sampling, obtain and ,according to get ,according to , and the During the second sampling , , Get the first During the second sampling , , ;in For the first During the second sampling , , All are sampled values; S2.3.3 According to , , get ,judge Does it meet the error accuracy requirements? When the error accuracy requirement is met, the sampling time As the optimal hysteresis characteristic parameter vector; If the error accuracy requirement is not met, repeat step S2.3.2 in the next sampling.

5. A high-precision loading method with adaptive gap compensation function according to claim 4, characterized in that, set up .

6. A high-precision loading method with adaptive gap compensation function according to claim 1, characterized in that, The method for obtaining the true displacement value of the tested servo mechanism corresponding to the sampled displacement value of the loaded hydraulic cylinder based on the gap error model after identifying the hysteresis characteristic parameters is as follows: Based on the gap error model after identifying the hysteresis characteristic parameters, a gap error compensation model is established, and the sampled displacement value of the loaded hydraulic cylinder is substituted into the gap error compensation model to obtain the true displacement value of the tested servo mechanism.

7. A high-precision loading method with adaptive gap compensation function according to claim 6, characterized in that, The true value of the displacement of the servo mechanism under test is denoted as The gap error compensation model is as follows: 。

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