A method for eliminating pose holding error in a proportional servo hydraulic system

Abstract

This invention discloses a method for eliminating pose holding error in a proportional servo hydraulic system. By using a dynamic method to eliminate the accumulation of error energy, the error energy is kept below the critical value of the hydraulic system's drive energy, thereby eliminating pose holding error and reducing the repositioning adjustment actions of the precision hydraulic control system.

Description

Technical Field

[0001] This invention relates to the field of servo hydraulic system technology, and in particular to a method for eliminating pose holding error in a proportional servo hydraulic system. Background Technology

[0002] The core operating loops of modern industrial control systems widely rely on proportional servo hydraulic systems. As a core component of hydraulic drive systems requiring precise positioning and strict posture maintenance, proportional servo systems offer advantages such as high positioning accuracy, fast response, and flexible switching. However, due to limitations in operating power, high-precision proportional servo systems are often used as secondary control components in large-operating-power hydraulic systems. A hydraulic amplification device is needed to amplify the positioning function of the proportional servo system to the primary hydraulic system. Some small-operating-power hydraulic systems use proportional servo systems to directly control positioning.

[0003] In theory, once a proportional servo hydraulic system completes positioning, it will remain in the target pose without further adjustment, thus entering a resting state. However, due to the inherent internal leakage of all hydraulic valves, and the gradual accumulation of leaked hydraulic media within the control system as the proportional servo system maintains its pose, when the energy of the accumulated media reaches a critical value for the hydraulic system's drive energy, the originally precisely positioned pose will shift, causing a repositioning adjustment in the hydraulic control system. This results in periodic fluctuations in the previously resting hydraulic system. While advancements in valve design and manufacturing processes have enabled precision-fitted valves to control internal leakage within a certain range, complete elimination is still impossible. For some highly demanding precision hydraulic control systems, repositioning adjustments caused by pose-holding errors can pose significant risks to the hydraulic system. Summary of the Invention

[0004] The purpose of this invention is to provide a method for eliminating pose holding errors in a proportional servo hydraulic system in order to solve the above-mentioned problems. This invention utilizes a dynamic method to eliminate the accumulation of error energy, so that the error energy is always kept below the critical value of the hydraulic system's drive energy, thereby achieving the purpose of eliminating pose holding errors and reducing the repositioning adjustment actions of the precision hydraulic control system.

[0005] The present invention achieves the above objectives through the following technical solutions:

[0006] A method for eliminating pose holding error in a proportional servo hydraulic system includes a drive energy critical value measurement unit 1, a proportional servo system response period measurement unit 2, a proportional servo system response amplitude measurement unit 3, an error elimination parameter calculation unit 4, an oscillation signal generation unit 5, and a proportional servo control signal generation unit 6.

[0007] The drive energy critical value measurement unit 1, the proportional servo system response period measurement unit 2, the proportional servo system response amplitude measurement unit 3, and the error elimination parameter calculation unit 4 only operate when the error elimination parameter calculation process is started. They are used to perform dynamic characteristic tests on the control system under test conditions, transmit the test data to the error elimination parameter calculation unit 4 to calculate the error elimination parameters A and F, transmit them to the oscillation signal generation unit 5, and generate control signal oscillation waveforms with the proportional servo control signal generation unit 6 to eliminate errors.

[0008] A further proposed solution is that the calculation process of the error elimination parameter calculation unit includes the following steps:

[0009] Step 1: Set the control dead zone to 0, so that the proportional servo hydraulic system cannot enter a steady state and the system enters an oscillating state.

[0010] Step 2: Record the oscillation waveform of the proportional servo control signal and transmit it to the drive energy critical value measurement unit to analyze the oscillation waveform and obtain the oscillation amplitude α of the proportional servo signal;

[0011] Step 3: Record the oscillation waveform of the hydraulic system and transmit it to the proportional servo system response period measurement unit and the proportional servo system response amplitude measurement unit to analyze the oscillation waveform and obtain the oscillation period τ and amplitude λ of the hydraulic system, respectively.

[0012] Step 4: Set the control dead zone to λ*1.2 to stop the hydraulic system from oscillating and allow it to return to a steady state.

[0013] A further approach involves the error elimination parameter calculation unit using α and 1 / τ as initial oscillation parameters to calculate A and F (representing the amplitude and frequency of the oscillation signal, respectively), which are then transmitted to the oscillation signal generation unit to generate a proportional servo control oscillation signal to induce system oscillation.

[0014] A further approach involves starting a loop of steps 1-3. In each loop cycle, the oscillation signal generation unit generates a corresponding proportional servo control oscillation signal based on the oscillation parameters of the error elimination calculation unit. This signal is then used to control the proportional servo valve via the proportional servo system control interface, thereby triggering system oscillation. The error elimination calculation unit then iterates the oscillation parameters based on the measured values ​​of α, τ, and λ to reduce system oscillation.

[0015] A further approach involves iterating the oscillation parameters, causing the system oscillations to gradually weaken. When α, τ, and λ reach set thresholds, the system oscillations are considered to have decayed to an extremely weak state. In this state, the applied oscillation signal will eliminate the pose-holding error without causing additional actions from lower-level control components. The corresponding oscillation parameters then become the error elimination parameters, and the error elimination parameter calculation process concludes.

[0016] A further proposed approach is to have the error elimination parameter calculation unit execute once per cycle, updating the values ​​of A and F. Once α, τ, and λ reach the threshold, the parameter calculation is complete, and the process ends.

[0017] A further solution involves using the path recording function added in step 1 to calculate in real time the percentage of the area scratched off by the user in the total area of ​​the verification code region. To improve the user experience, the user's mouse drag events are "throttled" during the real-time calculation process of the path recording function. When the percentage of the area reaches a threshold, the returned verification code is retrieved and automatically filled into the verification code box.

[0018] The beneficial effects of this invention are as follows:

[0019] 1. A dynamic pose retention error elimination method was implemented to maintain the stability of the proportional servo hydraulic control system and effectively reduce the repositioning adjustment of the precision hydraulic control system.

[0020] 2. An error elimination parameter calculation process was proposed, which realizes the function of automatically conducting dynamic characteristic tests of the control system and calculating error elimination parameters.

[0021] 3. This invention is applicable to the general configuration of proportional servo hydraulic control systems and requires no additional hardware. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a block diagram of the method of the present invention.

[0024] Figure 2 This is a flowchart of the error elimination parameter calculation process for the present invention.

[0025] Figure 3 This is a diagram of the error elimination parameter calculation unit algorithm of the present invention.

[0026] Figure 4 This is a schematic diagram of the invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0028] In any embodiment, such as Figure 1-4 As shown, the present invention provides a method for eliminating position holding error in a proportional servo hydraulic system, comprising a drive energy critical value measuring unit 1, a proportional servo system response period measuring unit 2, a proportional servo system response amplitude measuring unit 3, an error elimination parameter calculation unit 4, an oscillation signal generating unit 5, and a proportional servo control signal generating unit 6.

[0029] The drive energy critical value measurement unit 1, proportional servo system response period measurement unit 2, proportional servo system response amplitude measurement unit 3, and error elimination parameter calculation unit 4 only operate when the error elimination parameter calculation process is initiated. They are used to perform dynamic characteristic tests on the control system under test conditions, transmitting the test data to the error elimination parameter calculation unit 4 to calculate the error elimination parameters A and F, which are then transmitted to the oscillation signal generation unit 5 to generate a control signal oscillation waveform for error elimination. Under normal hydraulic system operation, parts 1, 2, 3, and 4 do not participate in the operation. The error elimination parameter calculation process is as follows: Figure 2 As shown. The internal algorithm of error elimination parameter calculation unit 4 is as follows. Figure 3 As shown.

[0030] The working principle of this invention is as follows:

[0031] The cause of pose holding error in a proportional servo hydraulic system is that the energy accumulated in the medium within the hydraulic system reaches a critical value of the hydraulic system's driving energy, causing a shift in the originally precisely positioned pose. This invention eliminates the accumulation of error energy by disrupting the medium accumulation process within the hydraulic system, keeping the accumulated error energy below the driving energy level, thus eliminating pose holding error. Specifically, after the proportional servo hydraulic system completes positioning, its control element, the proportional servo valve, should remain in the intermediate position. At this time, an oscillation signal with appropriate amplitude and frequency is applied to the proportional servo hydraulic system control signal, causing the proportional servo valve to frequently switch between open and closed positions. Because the amplitude of this oscillation signal is sufficiently small and the frequency sufficiently fast, the frequent switching of the proportional servo valve is insufficient to drive the lower-level control components, but it provides a pathway for the discharge of the driving medium from the lower-level control components, preventing them from accumulating sufficient error energy and thus achieving the pose holding error elimination function. The principle is as follows: Figure 4 As shown.

[0032] In this invention, the error elimination parameter calculation unit 4 performs the error elimination parameter calculation process ( Figure 2 This determines the amplitude and frequency of the oscillation signal, eliminating pose holding errors without causing additional actions in lower-level control components.

[0033] Error elimination parameter calculation process: For all proportional servo hydraulic systems, there is a control dead zone parameter. When the system's |adjustment target - actual value| ≤ control dead zone, the proportional servo hydraulic system has reached its adjustment target and stops adjusting, entering a steady state. For example... Figure 2 As shown, in step 1 of this process, the control dead zone is set to 0, preventing the proportional servo hydraulic system from entering a steady state and causing the system to enter an oscillating state. For a proportional servo hydraulic system with properly set control system parameters, in the oscillating state, the system waveform will exhibit a periodic, constant-amplitude oscillation waveform, while its proportional servo control signal will also exhibit an oscillation waveform with the same period as the system oscillation but a different amplitude.

[0034] In steps 2 and 3, the oscillation waveforms of the proportional servo control signal and the hydraulic system are recorded and transmitted to the drive energy critical value measurement unit, the proportional servo system response period measurement unit, and the proportional servo system response amplitude measurement unit to analyze the oscillation waveforms and obtain the proportional servo signal oscillation amplitude α, the hydraulic system oscillation period τ, and the amplitude λ, respectively.

[0035] Step 4: Set the control dead zone to λ*1.2 to stop the hydraulic system from oscillating and allow it to return to a steady state.

[0036] The error elimination parameter calculation unit uses α and 1 / τ as initial oscillation parameters to calculate A and F (representing the amplitude and frequency of the oscillation signal, respectively), which are then transmitted to the oscillation signal generation unit to generate a proportional servo control oscillation signal to induce system oscillation.

[0037] The loop sequence L1, L2, L3 begins. Within each loop cycle, the oscillation signal generation unit generates a corresponding proportional servo control oscillation signal based on the oscillation parameters of the error elimination calculation unit. This signal is then used to control the proportional servo valve via the proportional servo system control interface, thereby triggering system oscillation. The error elimination calculation unit then iterates the oscillation parameters based on the measured values ​​of α, τ, and λ to reduce system oscillation.

[0038] As the oscillation parameters iterate, the system oscillation gradually weakens. When α, τ, and λ reach the set thresholds, the system oscillation is considered to have decayed to an extremely weak state. In this state, the applied oscillation signal will eliminate the pose holding error without causing additional actions from the lower-level control components. The corresponding oscillation parameters become the error elimination parameters, and the error elimination parameter calculation process ends.

[0039] For the specific algorithm within the error elimination parameter calculation unit, see [link to algorithm]. Figure 3The unit algorithm is executed once in each loop cycle, updating the values ​​of A and F. Once α, τ, and λ reach the threshold, the parameter calculation is complete and the process ends.

[0040] This invention applies an oscillation signal with appropriate amplitude and frequency to a proportional servo valve. The frequent switching of the proportional servo valve between the open and closed positions allows the control medium chambers on both sides of the lower-level control component to be connected to the discharge passage. As a result, the control medium chamber of the lower-level control component can never accumulate enough medium, thus eliminating the position holding error of the lower-level control component.

[0041] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims. It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately. Furthermore, various different embodiments of the present invention can also be arbitrarily combined, as long as they do not violate the spirit of the present invention, they should also be considered as the content disclosed in the present invention.

Claims

1. A method for eliminating pose holding error in a proportional servo hydraulic system, characterized in that, It includes a drive energy critical value measurement unit, a proportional servo system response period measurement unit, a proportional servo system response amplitude measurement unit, an error elimination parameter calculation unit, an oscillation signal generation unit, and a proportional servo control signal generation unit; Among them, the drive energy critical value measurement unit, the proportional servo system response period measurement unit, the proportional servo system response amplitude measurement unit, and the error elimination parameter calculation unit only work when the error elimination parameter calculation process is started; it is used to perform dynamic characteristic tests on the control system under test conditions, transmit the test data to the error elimination parameter calculation unit and calculate the error elimination parameters, transmit them to the oscillation signal generation unit, and generate control signal oscillation waveforms with the proportional servo control signal generation unit to eliminate errors; The calculation process of the error elimination parameter calculation unit includes the following steps: Step 1: Set the control dead zone to 0, so that the proportional servo hydraulic system cannot enter a steady state and the system enters an oscillating state; Step 2: Record the oscillation waveform of the proportional servo control signal and transmit it to the drive energy critical value measurement unit to analyze the oscillation waveform and obtain the oscillation amplitude α of the proportional servo signal; Step 3: Record the oscillation waveform of the hydraulic system and transmit it to the proportional servo system response period measurement unit and the proportional servo system response amplitude measurement unit to analyze the oscillation waveform and obtain the oscillation period τ and amplitude λ of the hydraulic system, respectively. Step 4: Set the control dead zone to λ*1.2 to stop the hydraulic system from oscillating and allow it to return to a steady state. The error elimination parameter calculation unit uses α and 1 / τ as initial oscillation parameters to calculate the amplitude A and frequency F of the oscillation signal, which are then transmitted to the oscillation signal generation unit to generate a proportional servo control oscillation signal to induce system oscillation.

2. The method for eliminating pose holding error in a proportional servo hydraulic system as described in claim 1, characterized in that, The cycle of steps 1-3 begins. In each cycle, the oscillation signal generation unit generates a corresponding proportional servo control oscillation signal based on the oscillation parameters of the error elimination calculation unit. The signal is then used to control the proportional servo valve through the proportional servo system control interface, thereby triggering system oscillation. The error elimination calculation unit then iterates the oscillation parameters based on the measured values ​​of α, τ, and λ to reduce system oscillation.

3. The method for eliminating pose holding error in a proportional servo hydraulic system as described in claim 2, characterized in that, As the oscillation parameters iterate, the system oscillation gradually weakens. When α, τ, and λ reach the set threshold, the system oscillation is considered to have decayed to an extremely weak state. The oscillation signal applied in this state will eliminate the pose holding error without causing additional actions of the lower-level control components. The corresponding oscillation parameters become the error elimination parameters, and the error elimination parameter calculation process ends.

4. The method for eliminating pose holding error in a proportional servo hydraulic system as described in claim 2, characterized in that, The error elimination parameter calculation unit executes once per cycle, updating the amplitude A and frequency F of the oscillation signal. Once α, τ, and λ reach the threshold, the parameter calculation is complete, and the process ends.

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