A fatigue test process management method and system based on PLCopen specification

Abstract

The present invention belongs to the technical field related to industrial automation and discloses a fatigue test process management method and system based on the PLCopen specification. The method comprises the following steps: a controller obtains test configuration information and load spectrum information for each test from a host computer; the host computer issues a load spectrum control command to the controller, generates a load spectrum instruction, and transmits it to an actuator performing the test; the actuator receives the test configuration information and load spectrum instruction transmitted by the controller, performs the test, monitors the load spectrum response during the test in real time, and feeds it back to the controller; the controller generates a corresponding compensation amount for the load spectrum instruction according to a preset load spectrum compensation method, and feeds this compensation amount back to the actuator, which then compensates the corresponding load spectrum response according to the compensation amount. The present invention is highly scalable and easy to operate, and can be used in a variety of fields, such as automotive road spectrum simulation and fatigue testing of large components.

Description

Technical Field

[0001] The present invention belongs to the technical field related to industrial automation, and more specifically, relates to a fatigue test process management method and system based on the PLCopen specification. Background Art

[0002] Loading tests are a typical measurement and control application scenario in industrial automation. They assess the ability of a test piece to maintain its original performance under specific operating conditions and are widely used in a variety of technological fields, including shipbuilding, automotive, vibration tables, and earthquake simulation test benches. Compared to other drive methods, electro-hydraulic servo drives are the most common form of drive in mechanical loading tests due to their high power-to-weight ratio, strong load-bearing capacity, and high stiffness. This has led to the construction of large-scale coordinated loading test systems.

[0003] Patent CN113291489A discloses a loading device and method suitable for static testing of large-deformation landing gear structures. It is suitable for loading large-deformation landing gear structures in static testing and is limited to the technical field of static testing. Patent CN111470065A discloses a safety alarm device and method for aircraft structural strength testing. It outputs out-of-limit, out-of-tolerance, and emergency signals, and uses different LED colors and different alarm prompt sounds to distinguish the alarm levels, but does not explain the load spectrum instructions and load spectrum compensation of the coordinated loading control system. Patent CN111017260A discloses a synchronous coordinated loading control system for hydraulic and gas load loading equipment. It performs a static test on the entire aircraft, but does not provide a correction method for the static test. Patent CN105336252A discloses a method for coordinated loading of statically indeterminate structural loads and displacements. By establishing a displacement function relationship between the target point and the associated point, the applied displacement load on the displacement actuator is obtained.

[0004] The above content usually binds the loading system to the loading device, which limits the flexibility and scalability of the coordinated loading control system. A prominent feature of the coordinated loading control system is that in addition to designing conventional static spectrum tests and periodic spectrum tests, it can also be flexibly arranged by the user according to specific test scenarios to obtain any test load spectrum. In addition, when the test piece is a large component, the stress characteristics and strength characteristics of different loading areas are inconsistent. In this case, the test of the large component needs to be grouped, and load spectrum instruction management, load spectrum generation, and load spectrum coordination compensation should be implemented separately for each group to obtain a more reasonable overall test effect. Summary of the Invention

[0005] In response to the above-mentioned defects or improvement needs of the prior art, the present invention provides a fatigue test process management method and system based on the PLCopen specification, which solves the problems of difficult management of multiple test groups, low flexibility in load spectrum arrangement, and coordinated compensation of inconsistent multi-channel load loading responses.

[0006] To achieve the above object, according to one aspect of the present invention, a fatigue test process management method based on the PLCopen specification is provided, the method comprising the following steps:

[0007] The controller obtains the test configuration information and load spectrum information of each test from the host computer. The host computer sends a load spectrum control command to the controller. The controller generates a load spectrum instruction according to the load spectrum control command and the load spectrum information and transmits it to the actuator performing the test.

[0008] The actuator receives the test configuration information and load spectrum instructions transmitted by the controller to perform the test, monitors the load spectrum response during the test in real time and feeds back the response to the controller. The controller generates a compensation amount for the corresponding load spectrum instruction according to a preset load spectrum compensation method, feeds back the compensation amount to the actuator, and the actuator compensates for the corresponding load spectrum response according to the compensation amount.

[0009] Further preferably, the controller is provided with two layers of functional block sets corresponding one-to-one to each test of the part to be tested, namely a group and a channel, wherein the group is used to correspond to each test in the host computer, and the channel is used to respond to the load spectrum control command from the host computer, generate load spectrum information and generate compensation, and the interfaces of the group and channel comply with the PLCopen specification.

[0010] Further preferably, the load spectrum information includes load spectrum type and parameters, and the load spectrum type includes static spectrum, periodic spectrum and user-defined spectrum, wherein the user-defined spectrum is composed of the static spectrum and periodic spectrum.

[0011] Further preferably, the load spectrum instructions include static spectrum instructions, periodic spectrum instructions and user-defined spectrum instructions, which respectively refer to applying load on the test piece according to the static spectrum, periodic spectrum and user-defined spectrum.

[0012] Further preferably, the load spectrum control commands include normal playback-related test commands and special test commands, the normal playback-related test commands include start, pause, resume and stop test commands, and the characteristic test commands include emergency stop test commands.

[0013] Further preferably, when the control instruction is a static spectrum instruction, the preset load spectrum compensation method includes a time correction method and an amplitude correction method, which are respectively as follows:

[0014] Time correction method:

[0015] (a) The tracking error is always within the preset threshold and no correction is required;

[0016] (b) If the tracking error is within the preset threshold and the holding time is greater than the preset minimum holding time, no correction is required;

[0017] (c) If the tracking error is within the preset threshold and the hold time is less than the preset minimum hold time, the hold time ΔT needs to be compensated. h' , ΔT h' =t s +T hmin -T h , T hmin is the minimum hold time;

[0018] (d) The tracking error cannot always be within the preset threshold range, and the holding time needs to be extended. The holding time is ΔT h' , ΔT h' =t s +1.2*T hmin -T h , t s It is the adjustment time;

[0019] (e) The tracking error shows an oscillating trend and enters the preset threshold range, and then leaves the preset threshold range. The timing starts from the moment of entering the preset threshold range and the time t is maintained. h If it is greater than the preset minimum holding time setting value, no correction is required;

[0020] (f) The tracking error shows an oscillating trend and enters the preset threshold range, and then leaves the preset threshold range. The timing starts from the moment of entering the preset threshold range, and the actual holding time t h Less than the preset minimum holding time setting value T hmin , need to compensate the holding time ΔT h' , ΔT h' =t s +T hmin -T h ;

[0021] The amplitude correction method is:

[0022]

[0023] Among them, x0 is the command value of the static spectrum in the holding section, p1 is the linear correction factor, p2 is the nonlinear correction factor, e is the load spectrum tracking error value, δ L is the lower limit of the tracking error preset threshold, δ U is the upper limit of the preset threshold of the tracking error, and Δx is the compensation amount of the load spectrum instruction. When the load spectrum tracking error is less than the lower limit of the preset allowable error band, the adjustment increment is p1 times the load spectrum instruction value; when the load spectrum tracking error is greater than the lower limit of the error band and less than the expected load spectrum instruction, the adjustment increment is p1e times the load spectrum instruction value. -p2ttimes is the adjustment increment; when the load spectrum tracking error is greater than the expected load spectrum instruction and less than the upper limit of the error band, the load spectrum instruction value -p1e -p2t The adjustment increment is -p1 times the load spectrum command value. When the load spectrum tracking error exceeds the upper limit of the error band, the adjustment increment is -p1 times the load spectrum command value. The selection of p1 is related to the speed of the load spectrum response. The default value is 0.01 and can be fine-tuned according to the actual test scenario. The default value of p2 is 0.5.

[0024] Further preferably, when the control instruction is a periodic spectrum instruction, the preset load spectrum compensation method is as follows:

[0025] Adjust the offset value of the load spectrum waveform so that the actual load spectrum of the response and the waveform mean of the load spectrum instruction are on the same horizontal line;

[0026] Adjust the phase error so that the actual load spectrum of the response is synchronized with the phase of the load spectrum instruction;

[0027] The amplitude is pulled up or compressed longitudinally so that the actual load spectrum of the response is consistent with the amplitude of the load spectrum instruction.

[0028] Further preferably, when the control instruction is a custom spectrum instruction, the preset load spectrum compensation method is to first extract each sinusoidal component in the composite load spectrum using data fitting and successive approximation methods, and then coordinately compensate each sinusoidal component separately.

[0029] According to another aspect of the present invention, a fatigue test process management system based on the PLCopen specification is provided. The system includes an actuator configured to execute the fatigue test process management method based on the PLCopen specification.

[0030] According to another aspect of the present invention, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the fatigue test process management method based on the PLCopen specification is implemented.

[0031] In general, the above technical solutions conceived by the present invention have the following beneficial effects compared with the prior art:

[0032] 1. This invention addresses three typical issues in fatigue testing of large-scale aerospace structures: difficulty in grouping multiple tests, limited flexibility in load spectrum arrangement, and coordinated compensation for inconsistent multi-channel load responses. It implements a two-level collaborative mechanism of groups and channels to achieve group management of multiple tests. It uses static and periodic spectra as basic load spectrum units and then implements customized spectra through flexible arrangement. It also designs static spectrum load spectrum correction compensation, periodic spectrum correction compensation, and multi-frequency complex load spectrum correction compensation to achieve coordinated compensation for inconsistent multi-channel load spectrum loading responses.

[0033] 2. The present invention is designed based on the PLCopen specification's group and channel-level function blocks, enabling flexible configuration of various fatigue loading test types. Multiple tests can be run simultaneously, and the load spectrum types of the tests can also vary. This effectively addresses the flexibility requirements of the coordinated loading control system for diverse tests. Furthermore, functions related to load spectrum coordination tests, such as load spectrum control commands, load spectrum instruction generation, and load spectrum coordination compensation, are designed as PLCopen-compliant function blocks, facilitating cross-platform porting and subsequent functional scalability. Users can also expand existing functions with new load spectrum commands, load spectrum types, and other customized test functions.

[0034] 3. The function blocks of the present invention all comply with the PLCopen specification. The function block interface definition and internal implementation mechanism are easy for operators to understand. They can be ported to multiple programming platforms based on the IEC61131-3 standard. Users can also add custom function blocks within the existing framework to enrich and expand the functions of coordinated loading and load spectrum testing.

[0035] 4. The present invention considers the correction of the static load spectrum response during the hold step, including time compensation and amplitude compensation. In order to speed up the correction speed outside the allowable error range while reducing the correction accuracy within the allowable error range, an amplitude compensation method with a variable correction factor is adopted in different intervals;

[0036] 5. The present invention uses data fitting and successive approximation methods to extract the sinusoidal component parameters of the multi-frequency composite load spectrum, and combines peak-valley compensation and phase compensation technology to achieve asymptotic following of the multi-frequency composite load spectrum instructions. Before coordinated compensation, only the channel adjustment factor, adjustment upper limit, allowable error limit and other parameters need to be set. During the coordinated compensation process, there is no need to adjust the parameters of each channel involved in the loading, which reduces the difficulty of operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 is a flow chart of load spectrum management for a coordinated loading test constructed according to a preferred embodiment of the present invention;

[0038] Figure 2Schematic diagram of the hierarchical relationship between tests, PLCopen groups, and PLCopen channels constructed according to a preferred embodiment of the present invention;

[0039] Figure 3 It is a call relationship diagram of the PLCopen group function block and the PLCopen channel function block constructed according to the preferred embodiment of the present invention;

[0040] Figure 4 is a functional structure diagram of a PLCopen channel function block constructed according to a preferred embodiment of the present invention;

[0041] Figure 5 It is a complete waveform diagram of a custom load spectrum constructed according to a preferred embodiment of the present invention;

[0042] Figure 6 Schematic diagrams of six tracking responses of a static load spectrum constructed according to a preferred embodiment of the present invention, wherein (a) the tracking error is always within the preset threshold range and does not require time correction; (b) the tracking error enters the preset threshold range after a period of adjustment time and meets the minimum holding time requirement and does not require time correction; (c) the tracking error enters the preset threshold range after a period of adjustment time but does not meet the minimum holding time requirement and requires time correction; (d) the tracking error cannot always enter the preset threshold range and requires time correction; (e) the tracking error enters the preset threshold range with an oscillating trend, but the cumulative holding time is greater than the minimum holding time setting value and does not require time correction; (f) the tracking error enters the preset threshold range with an oscillating trend, but the cumulative holding time is less than the minimum holding time setting value and requires time correction;

[0043] Figure 7 It is an effect diagram of the coordinated correction of the static load spectrum constructed according to the preferred embodiment of the present invention;

[0044] Figure 8 This is an effect diagram of the coordinated correction of the periodic load spectrum constructed according to the preferred embodiment of the present invention;

[0045] Figure 9 This is an effect diagram of the change in amplitude tracking error of the periodic load spectrum coordinated correction constructed according to the preferred embodiment of the present invention;

[0046] Figure 10 This is an effect diagram of the phase error change coordinated correction of the periodic load spectrum constructed according to the preferred embodiment of the present invention;

[0047] Figure 11 This is an effect diagram of the coordinated correction of the composite load spectrum constructed according to the preferred embodiment of the present invention;

[0048] Figure 12It is an effect diagram of the composite load spectrum coordinated correction tracking error change constructed according to the preferred embodiment of the present invention. DETAILED DESCRIPTION

[0049] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is 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 for the purpose of explaining the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0050] A fatigue test process management and compensation method based on PLCopen specification, such as Figure 1 and 4 As shown, the following steps are included:

[0051] Step 1: Design a two-level function block set in the controller based on the PLCopen specification: group and channel.

[0052] Step 2: The controller parses the test configuration information and load spectrum information downloaded from the host computer, then receives control commands related to the load spectrum, generates load spectrum instructions, and downloads them to the execution structure via the high-speed Ethernet bus to drive the DUT to perform fatigue testing;

[0053] Step 3: The controller activates the coordinated compensation method that matches the load spectrum type to correct the load spectrum tracking error.

[0054] The contents described in this invention are all centered around the process management of fatigue testing and the load spectrum compensation function. Large-scale aviation structural parts are usually large in size. In order to better perform fatigue testing, the tested parts are usually tested in groups. Figure 2 As shown in the figure, the host computer configures the first experiment, which is recorded as experiment [1]. The participating channels in experiment [1] are: channel [1] and channel [2]. Channel [1] marked with an asterisk is set as the reference channel. The second experiment is recorded as experiment [2]. Experiment [2] includes channels [3], [4], etc., and channel [3] marked with an asterisk is set as the reference channel. This application scenario means that the controller needs to control two experiments at the same time.

[0055] In step 1, a two-level function block set based on the PLCopen specification is designed: group and channel. A PLCopen group is like a container, holding the channel sequences involved in the experiment. Therefore, the design of the PLCopen group function block set is specific to the experiment, with one PLCopen group corresponding to one experiment. If a experiment involves multiple channels, then the PLCopen group contains a set of channel sequences.

[0056] Step 1.1 is to design the PLCopen group function block set. Figure 3 As shown in the figure, in the controller identification area, the controller assigns the group index number GroupID 1 to the test [1]. The controller instantiates the PLCopen group function block set with the group index number 1 once, and can obtain access rights to all group function blocks with GroupID = 1. The group function blocks included in the group function set include group start [GMC_GroupStart], group stop [GMC_GroupStop], group pause [GMC_GroupPause], group resume [GMC_GroupResume], group reset [GMC_GroupReset], and group emergency stop [GMC_EmcyStop]. For example, when the controller receives the test [1] start command from the host computer, it calls the group start function block according to the start command and test name information of test [1], and distributes the start command to each participating channel in the group. Table 1 gives the names and explanations of the main function blocks in the PLCopen group function block set.

[0057] Table 1 PLCopen group function block names and function explanations

[0058]

[0059]

[0060] Step 1.2 is to design a channel function block set based on the PLCopen specification. Table 2 gives the main function blocks and function explanations in the channel function block set. The channel function block set mainly includes channel start [MC_Play], channel stop [MC_Stop], channel pause [MC_Halt], channel resume [MC_Resume], channel reset [MC_Reset], etc. Following the discussion in step 1.1, channel [1] and channel [2] both belong to group [1], and group [1] corresponds to test [1]. The producer-consumer design pattern is used to implement the distribution of PLCopen group commands to PLCopen channel commands. The PLCopen group distributes test control commands to the PLCopen channel, and the PLCopen channel responds to the test command and executes specific test behaviors. For example, when the controller executes the test [1] start command, channel [1] and channel [2] under group [1] both call the load spectrum play function block [MC_Play], so that both channel [1] and channel [2] start the test. Similarly, when the controller executes the test stop command, channel [1] and channel [2] under group [1] both call the load spectrum playback function block [MC_Stop], causing both channel [1] and channel [2] to stop the test.

[0061] The interface design of the channel function block complies with the PLCopen specification. Figure 3As shown in the figure, the input ports of a channel function block all have {ChID, Execute}. ChID is the channel serial number, corresponding to the specific hardware channel resource number; Execute is a Boolean value, and a rising edge triggers the execution of this function block. In addition, the output ports of a channel function block all have {Done, Busy, Error, ErrorID}. Done indicates that the channel has completed execution, Busy indicates that the channel function block is executing, and Error indicates an execution error in the channel function block, with the exception code displayed in ErrorID.

[0062] Table 2 PLCopen channel function block name and function explanation

[0063]

[0064]

[0065] In step 2, the controller parses the test configuration information and load spectrum information downloaded from the host computer, then receives control commands related to the load spectrum, generates load spectrum instructions, and downloads them to the execution structure via the high-speed Ethernet bus to drive the test piece to perform fatigue testing. The test configuration information includes the calibration coefficients, signal ranges, and filter frequencies of the sensors connected to the controller. The load spectrum information includes the load spectrum type and load spectrum parameters. The present invention supports three types of load spectrum: (1) static spectrum, (2) periodic spectrum, and (3) custom spectrum.

[0066] (1) Static spectrum structure. The static spectrum is composed of multiple steps in cascade, and each step contains four elements: current step value, current step duration, transition type, and transition time.

[0067] (2) Periodic spectrum structure. Periodic spectrum refers to a typical periodic signal, and its parameters include: waveform type, offset value, amplitude, frequency value, phase value, number of cycles, etc.

[0068] (3) Custom spectrum structure. Custom spectrum belongs to the load spectrum that can be flexibly arranged and designed independently by the present invention. It is a load spectrum obtained by arranging and combining the hold step, step step, periodic step, etc. according to the time history. When different step combinations are used, any custom spectrum can be obtained. In layman's terms, a static spectrum can be realized by a custom spectrum structure, and a periodic spectrum can also be realized by a custom spectrum structure. In addition, load spectrum steps with specific functions can be added on the basis of the static spectrum or the periodic spectrum. For example, Figure 5 As shown in the figure, on the basis of calling the periodic step, the step step, hold step, sine fade-in step and sine fade-out step are added to form a custom spectrum with specific functions.

[0069] In step 2, the controller receives load spectrum-related control commands, which include two categories: (1) normal play-related test commands, and (2) special test commands such as emergency stop.

[0070] (1) Normal playback related test commands

[0071] The test commands related to normal playback mainly include: start, pause, resume, stop and other test commands.

[0072] (2) Special test commands such as emergency stop

[0073] Commands related to safety protection are executed first, and all of them are emergency stop actions. The present invention takes into account the channel breakpoint protection and recovery functions during emergency stop actions. For load spectrum tests of large components, the total test time is usually very long. If a new test can only be restarted after an emergency stop test, it will lead to huge waste of resources and economic losses, and the test efficiency is also very low. Based on the structural characteristics of different load spectra, breakpoint protection and breakpoint recovery mechanisms are designed. Table 3 shows the breakpoint protection information of different load spectra. The breakpoint protection information records the test summary and spectrum information at the moment the emergency event occurs. The test summary includes: station name, test name, test type, group number, and number of channels in the group. Different load spectrum types have different spectrum information. For static tests, the breakpoint protection information uses the step as the smallest unit, and stores the total number of steps, the sequence number of the current step, the status of the current step, and the four elements of the current step {hold time, hold value, transition type, transition time}. For periodic tests, the breakpoint protection information stores the bias value, amplitude, frequency value, phase value and total number of cycles of the periodic characteristics. For custom tests, the breakpoint protection information uses nodes as the smallest unit. The node information includes the total number of nodes, the sequence number of the current node, the node type, the node parameter sequence, and the timestamp.

[0074] When recovering a load spectrum breakpoint, the configuration file is first reparsed based on the test information summary. The parsed spectrum information is then precisely located at the last breakpoint, with load spectrum recovery accuracy down to 1ms. This breakpoint is then used as the start time for the current test, and subsequent load spectra playback continues. Taking into account breakpoint recovery and protection functions triggered by emergency stops, load spectrum recovery time can be as accurate as 1ms, improving test efficiency and reducing testing costs.

[0075] Table 3 Breakpoint protection information

[0076]

[0077] In step 2, the PLCopen channel has already received the load spectrum information in advance, that is, it already knows the type of load spectrum to be played and its parameters. Therefore, when the PLCopen channel test start command is issued, the load spectrum playback function block is immediately called to generate the load spectrum instruction. The load spectrum instructions include: (1) static spectrum instruction, (2) periodic spectrum instruction, and (3) custom spectrum instruction.

[0078] Static spectrum instructions and periodic spectrum instructions belong to conventional load spectrum instructions. The present invention focuses on describing custom load spectrum instructions. Custom load spectrum is composed of a free combination of hold nodes, transition nodes, and periodic nodes. The attributes of the hold node include the current step value and the current step duration; the attributes of the transition node include the transition type and the transition time; the attributes of the periodic node include the typical parameters of the cyclic periodic wave. It can be considered that the custom load spectrum is formed by the flexible combination of the hold step and transition step in the static spectrum and the cyclic periodic wave of the periodic spectrum according to the test requirements. Therefore, when designing a custom load spectrum, the hold and transition functions in the static load spectrum are reused, and the cyclic periodic wave function of the periodic spectrum is also reused. In this way, the design of the custom load spectrum is simplified and the reusability of the module is improved.

[0079] Figure 5 It is a specific embodiment of a custom load spectrum. The custom spectrum consists of 5 nodes, namely: ① transition node, ② hold node, ③ period node, ④ hold node, ⑤ transition node. The ① transition node time is 5 seconds, the end value is 1.0, and the transition type is linear; the ② hold node time is 2 seconds; the ③ period node consists of sine fade-in, sine full wave, and sine fade-out, where the fade-in time and fade-out time are both 5 seconds, and the full wave time is 20 seconds; the ④ hold node time is 2 seconds; the ⑤ transition node time is 5 seconds, the end value is 0.0, and the transition type is linear.

[0080] Step 3: The controller activates the coordinated compensation method that matches the load spectrum type to correct the load spectrum tracking error. The load spectrum coordinated compensation includes: (1) static test load spectrum coordinated compensation, (2) periodic test load spectrum coordinated compensation, and (3) multi-frequency composite load spectrum coordinated compensation.

[0081] (1) Coordinated compensation of static test load spectrum.

[0082] The (1) coordinated compensation for the static test load spectrum is to correct the slow-responding channels during the hold phase. During the static test load spectrum loading process, it is necessary to detect whether the load response values ​​of all participating loading channels are within the preset threshold range during the hold phase, and enable correction functions for channels that do not meet the requirements, including amplitude correction and time correction. Amplitude correction is to adjust the load spectrum instruction value issued based on the load spectrum tracking error.

[0083] like Figure 6 (a), (b), (c), (d), (e), and (f) in the figure give an analysis of whether the static test load spectrum response compensates for the holding time in the holding section.

[0084] Table 4 Static test load spectrum coordination compensation (holding time)

[0085]

[0086]

[0087] In addition to the correction of the holding time, the downloaded load spectrum command value also needs to be corrected during the static test. During the test, the load response process of large structural parts is relatively slow. Therefore, the amplitude correction amount in each timing cycle cannot be too large, and the asymptotic amplitude correction method is appropriate. Specifically, x0 is the command value of the static spectrum in the holding section, p1 is the linear correction factor, p2 is the nonlinear correction factor, e is the load spectrum tracking error value, δ L is the lower limit of the tracking error preset threshold, δ U is the upper limit of the preset threshold value of the tracking error, and Δx is the compensation amount of the load spectrum instruction. When the load spectrum tracking error is less than the lower limit of the preset allowable error band, the adjustment increment is p1 times the load spectrum instruction value; when the load spectrum tracking error is greater than the lower limit of the error band and less than the expected load spectrum instruction, the adjustment increment is p1 times the load spectrum instruction value. times is the adjustment increment; when the load spectrum tracking error is greater than the expected load spectrum instruction and less than the upper limit of the error band, the load spectrum instruction value is used as the adjustment increment. The adjustment increment is -p1 times the load spectrum command value. When the load spectrum tracking error exceeds the upper limit of the error band, the adjustment increment is -p1 times the load spectrum command value. The selection of p1 is related to the speed of the load spectrum response. The default value is 0.01 and can be fine-tuned according to the actual test scenario. The default value of p2 is 0.5.

[0088]

[0089] like Figure 7 Figure 1 shows an example of a static test load spectrum consisting of 22 steps. Two channels are loaded simultaneously and symmetrically. The two rectangular boxes in the figure show a zoomed-in view of the static test correction. It can be seen that after correction, the load spectrum responses of both channels quickly track the load spectrum instructions and meet the minimum hold time requirement.

[0090] (2) Coordinated compensation of periodic test load spectrum.

[0091] The coordinated compensation of the load spectrum in periodic tests is to correct the offset value, amplitude, and phase value of the typical periodic signal to improve the load spectrum response capability of the channel. A sinusoidal periodic wave is used as a specific embodiment for illustration. The frequency domain response of the loading system includes DC component value, fundamental component value, higher harmonic component value, and noise value. If the fundamental component value is multiplied by the system response and integrated within the entire period of the fundamental wave, combined with the orthogonal nature of trigonometric functions, it can be seen that the integral value of the second-order or higher-order harmonic component is approximately 0. This method of multiplying with the fundamental signal and then integrating within the entire period has a strong anti-interference ability, and the amplitude-frequency characteristics and phase characteristics of the frequency domain response of the feedback signal can be obtained, and then the amplitude and phase values ​​can be obtained.

[0092] During the coordinated correction of the periodic spectrum, the horizontal axis represents the timestamp error, or phase difference, of the periodic spectrum test; the vertical axis represents the tracking error between the load spectrum response and the load spectrum instruction, which is composed of the superposition of the bias error and the amplitude error. First, the bias value is adjusted so that the waveform of the load spectrum response and the waveform mean of the load spectrum instruction are on the same horizontal line, and both maintain vertical symmetry with the end of the half-cycle as the reference point. Then, the phase error is corrected so that the load spectrum response and the load spectrum instruction maintain phase synchronization while maintaining the same mean value. Finally, the amplitude error is corrected by raising or compressing the amplitude from the vertical angle of the coordinate axis. It should be noted that the amplitude correction process may cause the phase error to slightly increase and then leave the phase tolerance band. Therefore, phase correction and amplitude correction must be performed alternately to achieve the desired effect.

[0093] Figure 8 、 Figure 9 、 Figure 10 This is a specific example of coordinated compensation of sinusoidal periodic load spectrum. The sinusoidal load spectrum offset values ​​and amplitudes of the five channels are the same, and the initial phase values ​​are 0°, 72°, 144°, 216°, and 288° respectively. For easy observation, Figure 8 Only the load spectrum waveforms of the first two channels are shown. After coordinated compensation, the load spectrum responses of the two channels approximately coincide with their respective desired load spectrum commands, with approximately equal amplitudes, and the phase difference between adjacent channels is essentially maintained at around 72°. Figure 9 This is a schematic diagram of the load spectrum tracking errors of the first three channels. The tracking errors of the three channels are all asymptotically close to the zero interval. Figure 10 Figure 3 is a schematic diagram of the phase error of the load spectra of the first three channels, all of which are approximately within the zero interval, thereby indirectly ensuring that the phase difference between adjacent channels is maintained around 72°.

[0094] (3) Coordinated compensation of composite load spectrum.

[0095] The (3) coordinated compensation of the composite load spectrum is divided into two steps: (1) extraction of the parameters of each sinusoidal component in the composite load spectrum; (2) coordinated compensation of each sinusoidal component. Due to unknown factors such as the structural characteristics, amplitude changes, phase offset, and noise of the hydraulic control system, it is very difficult to extract the parameters of the multi-frequency sinusoidal signal in the channel. The present invention uses data fitting and successive approximation methods to extract the multi-frequency signal parameters. The expression of the multi-frequency composite load spectrum response is as follows

[0096]

[0097] Where y(t) is the composite load spectrum response curve, M is the number of sinusoidal components of the multi-frequency load spectrum, and w k 、A k , ψ k is the parameter of the sinusoidal component, and c is the signal offset value. k It is preset.

[0098] The formula can be rewritten as

[0099]

[0100] Among them, a k =A k cosψ k 、b k =A k sinψ k .

[0101] These settings can be used to transform the problem into k If it is known, solve a k 、b k , c. The feedback signal usually contains noise, denoted as y i =y(t i )+e(t i ). First, define the error function

[0102]

[0103] Where N represents the number of sampling points, and N≥2M+1. Obviously, the ultimate goal is to find a suitable k 、b k , c, so that the error function obtains the minimum value. k 、b k , c take partial differentials, and let all partial differentials satisfy Then, using the data fitting idea, the fitting matrix is ​​defined as

[0104]

[0105] Where 1≤i≤M, 1≤j≤M, M is the number of sinusoidal components, and each element of the fitting matrix can be expressed as

[0106]

[0107] The fitting matrix is ​​a matrix with 2M+1 rows and 2M+1 columns. X is the coefficient column vector to be solved, and the number of elements in the coefficient column vector is 2M+1.

[0108] X=[a1 … a M b1 … b M c] T (7)

[0109] Z is a column vector associated with the sampling point value. The number of elements in the column vector is 2M+1. The column vector Z can be obtained by the following formula.

[0110]

[0111] Finally, the final coefficient column vector X is obtained as

[0112] X=[a1 … a M b1 … b M c] T =H -1 Z (9)

[0113] During the calculation process, the full cycle sampling is first performed and then the sampled data is downsampled, which can ensure full cycle sampling while reducing the size of the calculation matrix to improve the calculation efficiency. After the coefficient column vector X is estimated, the amplitude A of the M sinusoidal signal components in the composite spectrum can be obtained. k , phase value ψ k , 1≤k≤M.

[0114]

[0115] The offset values ​​of each sinusoidal component in the composite spectrum are accumulated and regarded as a total amplitude offset value. Therefore, the offset value of the composite spectrum needs to be corrected first by shifting the horizontal line of the center of the composite spectrum waveform up and down so that the actual total offset value approximately coincides with the expected total offset value.

[0116] After completing the correction of the composite spectrum offset value, the peak-valley phase compensation function is then used to compensate the amplitude and phase of each sinusoidal component of the composite spectrum, ultimately reducing the tracking error of the composite load spectrum to within a settable range. Definition A dk is the amplitude of the kth sinusoidal component in the desired instruction of the composite load spectrum, A k is the amplitude of the kth sinusoidal component in the composite load spectrum response, ΔA k is the amplitude difference of the kth sinusoidal component in the composite spectrum, Δψk is the phase difference of the kth sinusoidal component in the composite spectrum.

[0117]

[0118] The correction of the composite spectrum amplitude is divided into three cases.

[0119] (1)|ΔA k |≥δ A

[0120] The amplitude error in this case is outside the allowable error range and can be divided into two cases: If ΔA k ≥δ A , the load spectrum response is much smaller than the load spectrum instruction, and the actual instruction value of the kth sinusoidal component needs to be increased. The increased part is represented by ξ A *ΔA k If ΔA k ≤-δ A , the load spectrum response is much larger than the load spectrum instruction, and the actual instruction value of the kth sinusoidal component needs to be reduced. The reduced part is represented by ξ A *ΔA k Combining these two cases, we can see that |ΔA k |≥δ A When the load spectrum instruction actually downloaded is A k +ξ A *ΔA k .

[0121] (2)δ A / 2≤|ΔA k |<δ A

[0122] Although the amplitude error in this case is within the allowable error range, the load spectrum response is still somewhat different from the expected load spectrum instruction. It can be divided into two cases: If δ A / 2≤ΔA k <δ A , the load spectrum response is less than the load spectrum command, and the actual command value of the kth sinusoidal component needs to be increased. The increased part is calculated by 0.5*ξ A *ΔA k Indicates; if -δ A ≤ΔA k <-δ A / 2, the load spectrum response is greater than the load spectrum command, and the actual command value of the kth sinusoidal component needs to be reduced. The reduced part is 0.5*ξ A *ΔA k Combining these two cases, we can see that δ A / 2≤|ΔA k |<δ AWhen the load spectrum instruction actually downloaded is A k +0.5*ξ A *ΔA k .

[0123] (3)|ΔA k |<δ A / 2

[0124] In this case, the amplitude error is within the allowable error range, and the error between the load spectrum response and the expected load spectrum instruction is already very small, so only the error needs to be fine-tuned. k <δ A / 2, the load spectrum response is less than the load spectrum command, and the actual command value of the kth sinusoidal component needs to be appropriately increased. The increased part is calculated by 0.25*ξ A *ΔA k Indicates; if -δ A / 2≤ΔA k , the load spectrum response is slightly larger than the load spectrum command, and the actual command value of the kth sinusoidal component needs to be appropriately reduced. The reduced part is represented by 0.25*ξ A *ΔA k Combining these two cases, we can see that |ΔA k |<δ A / 2, the actual downloaded load spectrum instruction is A k +0.25*ξ A *ΔA k .

[0125]

[0126] The correction of the composite spectrum phase is also divided into three cases, and the compensation method is also carried out in stages.

[0127] The following formula gives the phase correction compensation method in stages.

[0128]

[0129] Figure 11 This verifies the correction and compensation function of the composite load spectrum. Table 5 lists the parameters of each sinusoidal component in the composite spectrum. Table 6 lists the correction parameters used for composite spectrum compensation. Figure 11 The upper half of the figure shows the waveform of the entire multi-frequency composite load spectrum. After coordinated compensation, it can be seen that the actual load spectrum response is approximately consistent with the expected load spectrum instruction. Figure 12 This is the trend diagram of the tracking error of the composite load spectrum. After correction, the maximum value of the tracking error is reduced from 7.3kN to 0.2kN.

[0130] Table 5 Correction parameters for periodic load spectrum compensation

[0131]

[0132]

[0133] Table 6 Correction parameters for composite load spectrum compensation

[0134]

[0135] It will be easily understood by those skilled in the art that the above description is merely 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 in the scope of protection of the present invention.

Claims

1. A fatigue test process management method based on PLCopen specification, characterized in that: The method comprises the following steps: The controller obtains the test configuration information and load spectrum information of each test from the host computer. The host computer sends a load spectrum control command to the controller. The controller generates a load spectrum instruction according to the load spectrum control command and the load spectrum information and transmits it to the actuator performing the test. The actuator receives the test configuration information and load spectrum instruction transmitted by the controller to perform the test, monitors the load spectrum response during the test in real time and feeds back the response to the controller. The controller generates a compensation amount for the corresponding load spectrum instruction according to a preset load spectrum compensation method, feeds the compensation amount back to the actuator, and the actuator compensates the corresponding load spectrum response according to the compensation amount. When the load spectrum control instruction is a static spectrum instruction, the preset load spectrum compensation method includes a time correction method and an amplitude correction method, which are as follows: Time correction method: (a) The tracking error is always within the preset threshold and no correction is required; (b) If the tracking error is within the preset threshold and the holding time is greater than the preset minimum holding time, no correction is required; (c) If the tracking error is within the preset threshold and the hold time is less than the preset minimum hold time, the hold time needs to be compensated. , , is the minimum hold time setting value; (d) The tracking error cannot always be within the preset threshold range, and the holding time needs to be extended. The holding time is , , t s It is the adjustment time; (e) If the tracking error oscillates and enters the preset threshold range, then leaves the preset threshold range, the timing starts from the moment it enters the preset threshold range, and the holding time is greater than the preset minimum holding time setting value, no correction is required; (f) The tracking error shows an oscillating trend and enters the preset threshold range, then leaves the preset threshold range. The timing starts from the moment of entering the preset threshold range, and the actual holding time is less than the preset minimum holding time setting value. , hold time compensation is required , ; The amplitude correction method is: in, is the command value of the static spectrum in the holding section, is the linear correction factor, is the nonlinear correction factor, is the load spectrum tracking error value, is the lower limit of the tracking error preset threshold, is the upper limit of the preset threshold of tracking error, is the compensation amount of the load spectrum instruction; The static spectrum is composed of multiple steps cascaded, each step contains four elements, namely the current step value, the current step duration, the transition type, and the transition time; The static spectrum instruction is to apply a load on the test piece according to the static spectrum.

2. A fatigue test process management method based on the PLCopen specification as claimed in claim 1, characterized in that: The controller is equipped with two layers of functional block sets, namely groups and channels, which correspond one to one with each test of the test piece. The groups are used to correspond to each test in the host computer, and the channels are used to respond to load spectrum control commands from the host computer, generate load spectrum information and generate compensation amounts. The interfaces of the groups and channels comply with the PLCopen specification.

3. A fatigue test process management method based on the PLCopen specification according to claim 1 or 2, characterized in that: The load spectrum information includes load spectrum type and parameters. The load spectrum type includes static spectrum, periodic spectrum and user-defined spectrum. The user-defined spectrum is composed of the static spectrum and periodic spectrum.

4. A fatigue test process management method based on PLCopen specification as claimed in claim 3, characterized in that: The load spectrum instructions include static spectrum instructions, periodic spectrum instructions and user-defined spectrum instructions, which respectively refer to applying loads on the test piece according to the static spectrum, periodic spectrum and user-defined spectrum.

5. A fatigue test process management method based on PLCopen specification as claimed in claim 1 or 2, characterized in that: The load spectrum control commands include normal play related test commands and special test commands. The normal play related test commands include start, pause, resume and stop test commands, and the special test commands include emergency stop test commands.

6. A fatigue test process management method based on PLCopen specification as claimed in claim 3, characterized in that: When the control instruction is a periodic spectrum instruction, the preset load spectrum compensation method is as follows: Adjust the offset value of the load spectrum waveform so that the actual load spectrum of the response and the waveform mean of the load spectrum instruction are on the same horizontal line; Adjust the phase error so that the actual load spectrum of the response is synchronized with the phase of the load spectrum instruction; The amplitude is pulled up or compressed longitudinally so that the actual load spectrum of the response is consistent with the amplitude of the load spectrum instruction.

7. A fatigue test process management method based on PLCopen specification as claimed in claim 3, characterized in that: When the control instruction is a user-defined spectrum instruction, the preset load spectrum compensation method is to first extract each sinusoidal component in the composite load spectrum using data fitting and successive approximation methods, and then coordinately compensate each sinusoidal component respectively.

8. A fatigue test process management system based on PLCopen specification, characterized in that: The system includes an actuator, which is used to execute the fatigue test process management method based on the PLCopen specification as described in any one of claims 1 to 7.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the fatigue test process management method based on the PLCopen specification as described in any one of claims 1 to 7 is implemented.

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