Method and apparatus for improving the synchronicity of a hydraulic cylinder and an electric cylinder

Abstract

This invention provides a method and apparatus for improving the synchronization of hydraulic cylinders and electric cylinders, comprising the following steps: acquiring the real-time time-domain signal of the hydraulic cylinder's actual position via a linear displacement sensor mounted on the hydraulic cylinder during a sampling time period; acquiring the real-time time-domain signal of the electric cylinder's actual position via a motor encoder; calculating the real-time accuracy errors of the hydraulic cylinder's and electric cylinder's real-time position time-domain signals respectively; obtaining the hydraulic cylinder's time delay and the electric cylinder's time delay based on the real-time accuracy errors; and compensating the control system for the time delays of the hydraulic cylinder and electric cylinder to improve the synchronization of the hydraulic cylinder and electric cylinder. This invention employs a hybrid hydraulic cylinder and electric cylinder approach to drive a multi-axis parallel mechanism, which, compared to a fully hydraulic cylinder or fully electric cylinder drive method, offers advantages such as greater driving force, higher load capacity, higher control precision, and greater stability of the parallel mechanism.

Description

Technical Field

[0001] This invention relates to the field of mechanical transmission technology, and in particular to a method and apparatus for improving the synchronization between hydraulic cylinders and electric cylinders. Background Technology

[0002] In typical parallel mechanism systems, either fully electric or fully hydraulic cylinders are used to drive the mechanism. While hydraulic cylinders offer greater load-bearing and driving force than typical electric cylinders, their control precision and stability are weaker. In some parallel mechanism systems, where both strong load-bearing capacity and high control precision and stability are required, it's necessary to use both hydraulic and electric cylinders simultaneously, maintaining a high degree of synchronization to ensure mechanism stability. For example, the Steward platform in an offshore stabilization platform needs to support sufficient weight while simultaneously moving multiple axes to maintain platform stability. Existing stabilization / vibration reduction / roll reduction equipment mostly uses fully electric / fully hydraulic cylinder devices for drive, but these mechanisms either have low load-bearing capacity, slow response speed, or low stability precision. Devices that simultaneously use a combination of electric and hydraulic cylinders are less common, mainly because the combined use of hydraulic and electric cylinders presents the following technical bottlenecks:

[0003] 1. The position control accuracy of hydraulic cylinders is not high, they are greatly affected by noise, and it is difficult to maintain the same synchronization with electric cylinders;

[0004] 2. Hydraulic cylinders have a slow response speed and relatively high delay, and the delay time is not fixed, making it difficult to directly improve the synchronization between hydraulic cylinders and electric cylinders through delay compensation. Summary of the Invention

[0005] The purpose of this invention is to provide a method and apparatus for improving the synchronization of hydraulic cylinders and electric cylinders, in order to solve the problems of low position control accuracy, slow response speed and high relative delay of hydraulic cylinders in some parallel mechanisms in the prior art, thereby improving the synchronization of hydraulic cylinders and electric cylinders.

[0006] The technical solution provided by this invention is as follows:

[0007] In some implementations, the steps include:

[0008] During the sampling period, the actual position time-domain signal of the hydraulic cylinder is obtained in real time through a linear displacement sensor, which is installed on the hydraulic cylinder.

[0009] The actual position time-domain signal of the electric cylinder is obtained through real-time feedback from the motor encoder.

[0010] Calculate the real-time accuracy error of the actual position time-domain signal of the hydraulic cylinder and the actual position time-domain signal of the electric cylinder, respectively;

[0011] The hydraulic cylinder time delay and electric cylinder time delay are obtained based on the real-time accuracy error.

[0012] The control system compensates for the time delays of the hydraulic cylinder and the electric cylinder, thereby improving the synchronization between the hydraulic cylinder and the electric cylinder.

[0013] Using a hybrid hydraulic / electric cylinder approach to drive the multi-axis parallel mechanism offers greater driving force and load capacity compared to a fully electric cylinder drive, while providing higher control precision and greater stability compared to a fully hydraulic cylinder drive.

[0014] In some embodiments, before obtaining the time-domain signal of the actual position of the hydraulic cylinder in real time through a linear displacement sensor during the sampling period, the method further includes:

[0015] During the sampling period, the target position time-domain signal curve sent by the servo controller is acquired. The target position time-domain signal curve is sent in the form of a sine function, and the formula for the sine function is:

[0016] x0(t) = Asin(2πBt),

[0017] Where A is the amplitude of the sine function and B is the frequency of the sine function.

[0018] In some embodiments, the real-time feedback acquisition of the actual position time-domain signal of the hydraulic cylinder through a linear displacement sensor specifically includes:

[0019] During the sampling time period, the actual position signal x1(t) of the hydraulic cylinder is first acquired, and then the time domain signal x2(t) of the actual position of the hydraulic cylinder is acquired after filtering.

[0020] In some embodiments, the step of first acquiring the actual position signal x1(t) of the hydraulic cylinder, and then processing it through a filter to obtain the time-domain signal x2(t) of the actual position of the hydraulic cylinder specifically includes:

[0021] First, the actual position signal x1(t) of the hydraulic cylinder is obtained, and then the actual position signal x1(t) of the hydraulic cylinder is converted into the frequency domain signal X1(ω) of the hydraulic cylinder through Fast Fourier Transform.

[0022] X1(ω) = fft(x1(t)),

[0023] The actual position frequency domain signal X1(ω) of the hydraulic cylinder is processed by a Butterworth low-pass filter to obtain the actual position frequency domain signal X2(ω). The Butterworth low-pass filter can be expressed by the formula of the square of the amplitude versus the frequency:

[0024]

[0025] Where n is the order of the filter, ω c ω is the cutoff frequency. p ε is the ratio of the passband edge frequency to the cutoff frequency;

[0026] Then, the frequency domain signal X2(ω) of the actual position of the hydraulic cylinder is converted into the time domain signal x2(t) of the actual position of the hydraulic cylinder through the inverse Fourier transform.

[0027] x2(t)=fft -1 (X2(ω)).

[0028] This implementation method uses a Butterworth low-pass filter to ensure that the frequency response curve within the passband is as flat as possible. Although the displacement data of the hydraulic cylinder will produce a phase delay, it effectively eliminates the influence of noise on the servo control of the hydraulic cylinder and signal acquisition.

[0029] In some embodiments, the calculation of the real-time accuracy error of the actual position time-domain signal of the hydraulic cylinder and the actual position time-domain signal of the electric cylinder specifically includes:

[0030] The actual position time-domain signal of the hydraulic cylinder is x2(t) with a time delay of τ0, and the actual position time-domain signal of the electric cylinder is x3(t) with a time delay of τ1. Then:

[0031]

[0032] Both the time delay τ0 and the time delay τ1 are on the order of milliseconds. The real-time accuracy error e0(t) of the hydraulic cylinder and the real-time accuracy error e1(t) of the electric cylinder are calculated as follows:

[0033]

[0034] In some embodiments, obtaining the hydraulic cylinder time delay and electric cylinder time delay based on the real-time accuracy error specifically includes:

[0035] Based on the actual position time domain signal x2(t) of the hydraulic cylinder and the actual position time domain signal x3(t) of the electric cylinder, the actual real-time accuracy errors e0(t) and e1(t) of the hydraulic cylinder and the electric cylinder are obtained. The time delay τ0 and the time delay τ1 are obtained by the least squares method.

[0036] In some implementations, obtaining the time delay τ0 and the time delay τ1 using the least squares method specifically includes:

[0037] According to the principle of least squares, the error between the actual and assumed displacement curves is:

[0038]

[0039] To minimize errors W0 and W1, we should have:

[0040]

[0041] Then, the time delay τ0 and the time delay τ1 are respectively calculated as follows:

[0042]

[0043] In this embodiment, the least squares method is used to calculate the sampling portions of the motor encoder and the displacement sensor at the hydraulic cylinder after low-pass filtering, obtaining the time delay between the displacement curves of the hydraulic cylinder and the electric cylinder after filtering. This delay is then incorporated into the control system for compensation, thereby improving the synchronization between the hydraulic cylinder and the electric cylinder.

[0044] Based on the same technical concept, the present invention also provides a device for improving the synchronization between a hydraulic cylinder and an electric cylinder, characterized in that it comprises:

[0045] The signal acquisition module is used to acquire the time-domain signal of the actual position of the hydraulic cylinder and the time-domain signal of the actual position of the electric cylinder;

[0046] The real-time accuracy error calculation module is used to calculate the real-time accuracy error of the actual position time domain signal of the hydraulic cylinder and the actual position time domain signal of the electric cylinder, respectively.

[0047] A time delay calculation module is used to obtain the hydraulic cylinder time delay and the electric cylinder time delay based on the real-time accuracy error.

[0048] The compensation module is used to compensate the control system for the time delay of the hydraulic cylinder and the electric cylinder, thereby improving the synchronization of the hydraulic cylinder and the electric cylinder.

[0049] In some embodiments, the signal acquisition module specifically includes:

[0050] The signal processing submodule is used to process the actual position signal of the hydraulic cylinder through a filter;

[0051] The signal conversion submodule is used to convert the actual position signal of the hydraulic cylinder into time domain and frequency domain.

[0052] In some embodiments, the device for improving the synchronization between the hydraulic cylinder and the electric cylinder further includes:

[0053] The synchronization improvement module is used to further improve the synchronization of the hydraulic cylinder and the electric cylinder by increasing the sampling time length until a preset requirement is met.

[0054] The method and apparatus for improving the synchronization of hydraulic cylinders and electric cylinders provided by the present invention have at least the following advantages:

[0055] 1. The present invention provides a method for improving the synchronization of hydraulic cylinders and electric cylinders by using a hybrid hydraulic cylinder / electric cylinder mode to drive a multi-axis parallel mechanism. Compared with the all-electric cylinder driving method, the driving force is greater and the load capacity is greater. Compared with the all-hydraulic cylinder driving method, the control precision is higher and the parallel mechanism is more stable.

[0056] 2. The method for improving the synchronization of hydraulic cylinders and electric cylinders provided by this invention uses an external wire displacement sensor to collect the position information of the hydraulic cylinder. Compared with the acquisition frequency of the industrial control computer board, the acquisition frequency is higher and the acquisition accuracy is higher. By selecting the acquisition frequency of the wire sensor, it can adapt to the electric cylinder motor under different control frequencies, so that the hydraulic cylinder and electric cylinder maintain the same acquisition frequency.

[0057] 3. The method for improving the synchronization between hydraulic cylinders and electric cylinders provided by this invention employs a Butterworth low-pass filter to process the position information of the hydraulic cylinder. The Butterworth low-pass filter can ensure that the frequency response curve within the passband is as flat as possible. Although a phase delay will occur after processing the displacement data of the hydraulic cylinder, it effectively eliminates the influence of noise on the servo control of the hydraulic cylinder and signal acquisition. Attached Figure Description

[0058] The preferred embodiments will now be described in a clear and easy-to-understand manner, with reference to the accompanying drawings, to further explain the above-mentioned characteristics, technical features, advantages, and implementation methods of a method and apparatus for improving the synchronization of a hydraulic cylinder and an electric cylinder.

[0059] Figure 1 This is a flowchart illustrating an embodiment of a method for improving the synchronization between a hydraulic cylinder and an electric cylinder provided by the present invention.

[0060] Figure 2 This is the filtering effect of using a Butterworth low-pass filter on the actual position signal of the hydraulic cylinder;

[0061] Figure 3 yes Figure 2 A magnified view of a portion of the image;

[0062] Figure 4 The diagram shows the synchronization test results when the synchronization method for lifting hydraulic cylinders and electric cylinders provided by this invention was not used.

[0063] Figure 5 yes Figure 4A magnified view of a portion of the image;

[0064] Figure 6 The diagram shows the synchronization test results of the lifting hydraulic cylinder and electric cylinder using the synchronization method provided by this invention.

[0065] Figure 7 yes Figure 6 A magnified view of a portion of the image;

[0066] Figure 8 This is a block diagram of one embodiment of a device for synchronizing a hydraulic cylinder and an electric cylinder provided by the present invention;

[0067] Figure 9 This is a block diagram of another embodiment of the device for synchronizing a hydraulic cylinder and an electric cylinder provided by the present invention. Detailed Implementation

[0068] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application can also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0069] It should be understood that, when used in this specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or sets.

[0070] It should also be further understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0071] Furthermore, in the description of this application, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0072] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the specific implementation methods of the present invention will be described below with reference to the accompanying drawings. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings and other implementation methods can be obtained based on these drawings without any creative effort.

[0073] In one embodiment, the present invention provides a method for improving the synchronization between a hydraulic cylinder and an electric cylinder, referencing... Figure 1 The steps include:

[0074] S100, during the sampling period, obtains the time domain signal of the actual position of the hydraulic cylinder in real time through the feedback of the linear displacement sensor, which is installed on the hydraulic cylinder.

[0075] The time-domain signal of the actual position of the hydraulic cylinder in this step is a relatively smooth curve obtained after being processed by a filter, which can effectively reduce the impact of noise.

[0076] S200 obtains the time-domain signal of the actual position of the electric cylinder in real time through the motor encoder feedback;

[0077] The actual position time-domain signal of the electric cylinder can be directly obtained through the motor encoder.

[0078] S300 calculates the real-time accuracy error of the actual position time-domain signal of the hydraulic cylinder and the actual position time-domain signal of the electric cylinder, respectively.

[0079] S400 obtains the time delay of the hydraulic cylinder and the time delay of the electric cylinder based on the real-time accuracy error.

[0080] The S500 compensates for the time delays of the hydraulic cylinders and electric cylinders in the control system, improving the synchronization of the hydraulic cylinders and electric cylinders. The synchronization of each axis can be further improved by increasing the sampling time.

[0081] Specifically, the hydraulic cylinder is equipped with a linear displacement sensor (also known as a wire sensor), which can provide real-time feedback on the actual position signal of the hydraulic cylinder. The actual position signal of the hydraulic cylinder is obtained by processing the actual position signal within the sampling time period. Within the same sampling time period, the actual position time signal of the electric cylinder is obtained in real-time through a motor encoder. Then, the real-time accuracy errors of the hydraulic cylinder's and the electric cylinder's actual position time signals are calculated separately. The time delays of the hydraulic cylinder and the electric cylinder are then calculated based on these real-time accuracy errors. Time compensation is then made in the control system based on these time delays to improve the synchronization between the hydraulic cylinder and the electric cylinder. The advantage of this approach is that a mixed use of hydraulic and electric cylinders can be used to drive multi-axis parallel mechanisms. Compared to a fully electric cylinder drive, this results in greater driving force and a higher load capacity. Compared to a fully hydraulic cylinder drive, this provides higher control precision and greater stability of the parallel mechanism.

[0082] In one embodiment, based on the above embodiment, before acquiring the time-domain signal of the actual position of the hydraulic cylinder in real time through the linear displacement sensor during the sampling period, the method further includes:

[0083] During the sampling period, the target position time-domain signal curve sent by the servo controller is acquired. The target position time-domain signal curve is sent in the form of a sine function, and the formula for the sine function is:

[0084] x0(t) = Asin(2πBt),

[0085] Where A is the amplitude of the sine function and B is the frequency of the sine function.

[0086] Specifically, within the sampling period, the target position time-domain curve x0(t) issued by the servo controller can be represented by a sine function. This approach simplifies subsequent calculations to account for accuracy errors and time delays.

[0087] In one embodiment, based on the above embodiments, the actual position time-domain signal of the hydraulic cylinder is obtained in real time through feedback from a linear displacement sensor, specifically including:

[0088] During the sampling period, the actual position signal x1(t) of the hydraulic cylinder is first obtained, and after filtering, the time domain signal x2(t) of the actual position of the hydraulic cylinder is obtained.

[0089] Specifically, the actual position signal x1(t) of the hydraulic cylinder, obtained directly from the real-time feedback of the linear displacement sensor, is characterized by high noise and a rough curve. It needs to be processed by a filter to obtain the time-domain signal x2(t) of the actual position of the hydraulic cylinder before it can be used in subsequent calculations. The filtering effect can be referenced. Figure 2 and its enlarged portion Figure 3 The diagram shows the Butterworth low-pass filter used. The time-domain signal of the actual position of the electric cylinder fed back by the motor encoder has relatively little noise, so it does not require filtering. The advantage of this approach is that it significantly improves the accuracy of the calculation and reduces interference from noise.

[0090] In one embodiment, based on the above embodiment, the actual position signal x1(t) of the hydraulic cylinder is first obtained, and then the time-domain signal x2(t) of the actual position of the hydraulic cylinder is obtained after filtering. Specifically, this includes:

[0091] First, obtain the actual position signal x1(t) of the hydraulic cylinder, and then convert the actual position signal x1(t) of the hydraulic cylinder into the frequency domain signal X1(ω) of the hydraulic cylinder through a fast Fourier transform.

[0092] X1(ω) = fft(x1(t)),

[0093] The actual position frequency domain signal X1(ω) of the hydraulic cylinder is obtained by processing it with a Butterworth low-pass filter. The Butterworth low-pass filter can be expressed by the formula of the square of the amplitude versus the frequency:

[0094]

[0095] Where n is the order of the filter, ω c ω is the cutoff frequency. p ε is the ratio of the passband edge frequency to the cutoff frequency;

[0096] Then, the inverse Fourier transform is used to convert the frequency domain signal X2(ω) of the actual position of the hydraulic cylinder into the time domain signal x2(t).

[0097] x2(t)=fft -1 (X2(ω)).

[0098] Specifically, in this embodiment, a Butterworth low-pass filter is used for processing. First, the actual position signal x1(t) of the hydraulic cylinder fed back in real time by the linear displacement sensor is converted into the frequency domain signal X1(ω) of the actual position of the hydraulic cylinder through Fast Fourier Transform (FFT). Then, it is processed by the Butterworth low-pass filter to obtain the frequency domain signal X2(ω) of the actual position of the hydraulic cylinder. The filtered curve produces displacement, reduces glitch noise, and makes the curve smoother. Finally, the obtained curve is converted into the time domain signal x2(t) of the actual position of the hydraulic cylinder through the inverse Fourier transform.

[0099] In one embodiment, based on the above embodiments, the real-time accuracy errors of the actual position time-domain signal of the hydraulic cylinder and the actual position time-domain signal of the electric cylinder are calculated respectively, specifically including:

[0100] The actual position time-domain signal of the hydraulic cylinder is x2(t), with a time delay of τ0; the actual position time-domain signal of the electric cylinder is x3(t), with a time delay of τ1. Then:

[0101]

[0102] Both time delays τ0 and τ1 are in the millisecond range. The real-time accuracy errors e0(t) of the hydraulic cylinder and e1(t) of the electric cylinder are calculated as follows:

[0103]

[0104] Specifically, the time-domain signal x2(t) of the actual position of the hydraulic cylinder and the time-domain signal x3(t) of the actual position of the electric cylinder can both be represented as sinusoidal functions with time delays. Assuming that the time delays are τ0 and τ1 respectively, then we have

[0105]

[0106] Since τ0 and τ1 are both in the millisecond range and have very small values, the real-time accuracy error e0(t) of the hydraulic cylinder and the real-time accuracy error e1(t) of the electric cylinder can be calculated.

[0107] In one embodiment, based on the above embodiments, the hydraulic cylinder time delay and electric cylinder time delay are obtained according to the real-time accuracy error, specifically including:

[0108] Based on the actual position time domain signal x2(t) of the hydraulic cylinder and the actual position time domain signal x3(t) of the electric cylinder, the actual real-time accuracy errors e0(t) and e1(t) of the hydraulic cylinder and the electric cylinder are obtained. The time delay τ0 and the time delay τ1 are obtained by the least squares method.

[0109] Specifically, based on the actual real-time accuracy errors e0(t) and e1(t) of the hydraulic cylinder and electric cylinder, -2πAcos(2πBt) at each moment can be calculated, and τ0 and τ1 can be obtained by using the least squares method.

[0110] In one embodiment, based on the above embodiments, the acquisition time delay τ0 and time delay τ1 are obtained by the least squares method, specifically including:

[0111] According to the principle of least squares, the error between the actual and assumed displacement curves is:

[0112]

[0113] To minimize errors W0 and W1, we should have:

[0114]

[0115] Then, the time delays τ0 and τ1 are calculated as follows:

[0116]

[0117] Specifically, when the collection time T OWhen the sinusoidal excitation amplitude A = 0.015m and frequency B = 0.5Hz is 32s, a parallel mechanism of hydraulic and electric cylinders is used to synchronize the four electric cylinders with the hydraulic cylinders placed to the side. The linear displacement sensor (wire sensor) used has a range of 500mm and an accuracy of 0.01mm. The Butterworth low-pass filter used is a 6th-order filter with a cutoff frequency of 10Hz. Using the least squares method, the synchronization delays of the hydraulic cylinders are calculated as follows: τ0 (synchronization delay of hydraulic cylinder 1) is 62.2521ms, τ1 (synchronization delay of electric cylinder 1) is 6.0894ms, τ2 (synchronization delay of electric cylinder 2) is 5.9568ms, τ3 (synchronization delay of electric cylinder 3) is 6.1634ms, and τ4 (synchronization delay of electric cylinder 4) is 5.9488ms. By compensating for the timing of the control commands of each subsequent axis by the control system (unifying the timing of each axis to the axis with the highest delay), it is possible to maintain the control frequency at 1kHz while ensuring that the synchronization delay of the position control of each axis is no more than 5ms. Figure 4 and its enlarged portion Figure 5 The displacement curves of hydraulic cylinders and electric cylinders that do not employ the synchronization method provided by this invention show a clear visual delay between the curves; while Figure 6 and its enlarged portion Figure 7 The displacement curves of the hydraulic cylinder and electric cylinder after adopting the method provided by this invention are such that the time delay of each axis cannot be distinguished by the naked eye.

[0118] In one embodiment, based on the same technical concept, the present invention also provides a device for improving the synchronization between a hydraulic cylinder and an electric cylinder, see reference. Figure 8 ,include:

[0119] Signal acquisition module 10 is used to acquire the time domain signal of the actual position of the hydraulic cylinder and the time domain signal of the actual position of the electric cylinder;

[0120] The real-time accuracy error calculation module 20 is used to calculate the real-time accuracy error of the actual position time domain signal of the hydraulic cylinder and the actual position time domain signal of the electric cylinder, respectively.

[0121] Time delay calculation module 30 is used to obtain the time delay of hydraulic cylinder and electric cylinder based on real-time accuracy error;

[0122] The compensation module 40 is used to compensate the control system for the time delay of the hydraulic cylinder and the electric cylinder, thereby improving the synchronization of the hydraulic cylinder and the electric cylinder.

[0123] Specifically, the signal acquisition module is used to collect signal data, including the actual position time domain signal of the hydraulic cylinder and the actual position time domain signal of the electric cylinder. Then, the real-time accuracy error calculation module calculates the real-time accuracy error of the actual position time domain signal of the hydraulic cylinder and the actual position time domain signal of the electric cylinder respectively. The real-time accuracy error is then used to calculate the time delay of the hydraulic cylinder and the time delay of the electric cylinder. Finally, the control system makes time compensation for the hydraulic cylinder and the electric cylinder to improve their synchronization.

[0124] In one embodiment, based on the above embodiments, referring to Figure 9 The signal acquisition module specifically includes:

[0125] The signal processing submodule 11 is used to process the actual position signal of the hydraulic cylinder through a filter;

[0126] The signal conversion submodule 12 is used to convert the actual position signal of the hydraulic cylinder into time domain and frequency domain.

[0127] Specifically, the signal acquisition module includes a signal processing submodule and a signal conversion submodule. The signal conversion submodule converts the actual position signal of the hydraulic cylinder between the time domain and the frequency domain, allowing the signal processing submodule to filter the signal and obtain a signal with less noise. This improves the accuracy of subsequent time delay calculations and enhances the synchronization between the hydraulic cylinder and the electric cylinder.

[0128] In one embodiment, based on the above embodiments, a device for improving the synchronization between a hydraulic cylinder and an electric cylinder further includes:

[0129] The synchronization enhancement module is used to further improve the synchronization of the hydraulic cylinder and the electric cylinder by increasing the sampling time length until the preset requirements are met.

[0130] Specifically, based on the calculated synchronization time error of each axis, time compensation is performed on each axis according to the instructions of the control system to improve the time synchronization of each axis. Displacement information of each axis is then collected again from the cable sensor and motor encoder for synchronization comparison. Increasing the acquisition time can further improve the synchronization of each axis until the synchronization meets the target requirements.

[0131] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0132] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0133] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0134] Furthermore, the functional units in the various embodiments of this application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The integrated unit described above can be implemented in hardware or as a software functional unit.

[0135] It should be noted that the above embodiments can be freely combined as needed. The above description is only a preferred embodiment of the present invention. It should be pointed out that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for improving the synchronization between a hydraulic cylinder and an electric cylinder, characterized in that, Including the following steps: During the sampling period, the actual position time-domain signal of the hydraulic cylinder is obtained in real time through a linear displacement sensor, which is installed on the hydraulic cylinder. The actual position time-domain signal of the electric cylinder is obtained through real-time feedback from the motor encoder. Calculate the real-time accuracy error of the actual position time-domain signal of the hydraulic cylinder and the actual position time-domain signal of the electric cylinder, respectively; The hydraulic cylinder time delay and electric cylinder time delay are obtained based on the real-time accuracy error. The control system makes time compensation based on the time delay of the hydraulic cylinder and the time delay of the electric cylinder to improve the synchronization of the hydraulic cylinder and the electric cylinder. Specifically, obtaining the hydraulic cylinder time delay and electric cylinder time delay based on the real-time accuracy error includes: Based on the actual position time domain signal of the hydraulic cylinder x 2 ( t The actual position time-domain signal of the electric cylinder is x 3 ( t This allows us to obtain the actual real-time accuracy error between the hydraulic cylinder and the electric cylinder. e 0( t )and e 1( t The time delay is obtained using the least squares method. τ 0 and the time delay τ 1; The time delay is obtained by the least squares method. τ 0 and the time delay τ 1. Specifically includes: According to the principle of least squares, the error between the actual and assumed displacement curves is: ， To make the error W 0 and error W 1 The minimum should be: ， Then, the time delays are calculated respectively. τ 0 and the time delay τ 1 is: 。 2. The method for improving the synchronization of a hydraulic cylinder and an electric cylinder according to claim 1, characterized in that, Before acquiring the actual position time-domain signal of the hydraulic cylinder through real-time feedback from a linear displacement sensor during the sampling period, the method further includes: During the sampling period, the target position time-domain signal curve sent by the servo controller is acquired. The target position time-domain signal curve is sent in the form of a sine function, and the formula for the sine function is: ， in, A The amplitude of the sine function is... B The frequency of the sine function is given.

3. The method for improving the synchronization of a hydraulic cylinder and an electric cylinder according to claim 2, characterized in that, The method of obtaining the actual position time-domain signal of the hydraulic cylinder through real-time feedback from a linear displacement sensor specifically includes: During the sampling time period, the actual position signal of the hydraulic cylinder is acquired first. x 1( t The actual position time-domain signal of the hydraulic cylinder is obtained after filtering. x 2 ( t ).

4. The method for improving the synchronization of a hydraulic cylinder and an electric cylinder according to claim 3, characterized in that, The first step is to obtain the actual position signal of the hydraulic cylinder. x 1( t The actual position time-domain signal of the hydraulic cylinder is obtained after filtering. x 2 ( t Specifically, this includes: First, obtain the actual position signal of the hydraulic cylinder. x 1( t The actual position signal of the hydraulic cylinder is obtained by fast Fourier transform. x 1( t Converted into frequency domain signal of actual position of hydraulic cylinder X 1( ω ), ， The actual position frequency domain signal of the hydraulic cylinder is processed by a Butterworth low-pass filter. X 1( ω The actual position frequency domain signal of the hydraulic cylinder is obtained. X 2( ω The Butterworth low-pass filter can be expressed using the formula for the square of the amplitude versus the frequency: ， in, n Let the order be the filter order. ω c The cutoff frequency, ω p These are the passband edge frequencies. ε It is the ratio of the passband edge frequency to the cutoff frequency; Then, the frequency domain signal of the actual position of the hydraulic cylinder is obtained by inverse Fourier transform. X 2( ω This is converted into the actual position time-domain signal of the hydraulic cylinder. x 2 ( t ) 。 5. A method for improving the synchronization of a hydraulic cylinder and an electric cylinder according to claim 4, characterized in that, The calculation of the real-time accuracy error of the actual position time-domain signal of the hydraulic cylinder and the actual position time-domain signal of the electric cylinder, respectively, specifically includes: The actual position time-domain signal of the hydraulic cylinder is x 2 ( t The time delay is... τ 0, the actual position time-domain signal of the electric cylinder is x 3 ( t The time delay is... τ 1, then we have: ， The time delay τ 0 and the time delay τ All values ​​are in the millisecond range, used to calculate the real-time accuracy error of the hydraulic cylinder. e 0( t Real-time accuracy error of electric cylinder e 1( t )for: 。 6. A device for improving the synchronization between a hydraulic cylinder and an electric cylinder, characterized in that, include: The signal acquisition module is used to acquire the time-domain signal of the actual position of the hydraulic cylinder and the time-domain signal of the actual position of the electric cylinder; The real-time accuracy error calculation module is used to calculate the real-time accuracy error of the actual position time domain signal of the hydraulic cylinder and the actual position time domain signal of the electric cylinder, respectively. A time delay calculation module is used to obtain the hydraulic cylinder time delay and the electric cylinder time delay based on the real-time accuracy error. The compensation module is used to compensate the control system for the time delay of the hydraulic cylinder and the electric cylinder, thereby improving the synchronization between the hydraulic cylinder and the electric cylinder. Specifically, the time delay calculation module is used to: calculate the time domain signal of the actual position of the hydraulic cylinder. x 2 ( t The actual position time-domain signal of the electric cylinder is x 3 ( t This allows us to obtain the actual real-time accuracy error between the hydraulic cylinder and the electric cylinder. e 0( t )and e 1( t The time delay is obtained using the least squares method. τ 0 and the time delay τ 1; The time delay is obtained by the least squares method. τ 0 and the time delay τ 1. Specifically includes: According to the principle of least squares, the error between the actual and assumed displacement curves is: ， To make the error W 0 and error W 1 The minimum should be: ， Then, the time delays are calculated respectively. τ 0 and the time delay τ 1 is: 。 7. The device for improving the synchronization of a hydraulic cylinder and an electric cylinder according to claim 6, characterized in that, The signal acquisition module specifically includes: The signal processing submodule is used to process the actual position signal of the hydraulic cylinder through a filter; The signal conversion submodule is used to convert the actual position signal of the hydraulic cylinder into time domain and frequency domain.

8. A device for improving the synchronization of a hydraulic cylinder and an electric cylinder according to claim 6 or 7, characterized in that, Also includes: The synchronization improvement module is used to further improve the synchronization of the hydraulic cylinder and the electric cylinder by increasing the sampling time length until a preset requirement is met.

Images