Method and device for obtaining a large magnitude step response of a feed system

Abstract

The present application belongs to the technical field of numerical control control, and discloses a kind of acquisition method and equipment of large amplitude step response of feed system, which comprises the following steps: (1) the front and rear of target step signal are respectively connected with acceleration sequence and deceleration sequence to form excitation signal;(2) first, the response data of feed system under the action of the excitation signal is obtained, and the response data includes the response corresponding to n acceleration and deceleration sequence step signals;Then, the response corresponding to n acceleration and deceleration sequence step signals is arranged from small to large in turn, and then the obtained order is iteratively solved to obtain the target step response.The present application connects a slow-varying acceleration process and a slow-varying deceleration process before and after the step signal respectively, expands the step signal into a splicing signal of continuous multiple periods and different amplitude step signals, thereby avoiding the speed mutation caused by large amplitude step signal.

Description

Technical Field

[0001] This invention belongs to the field of numerical control technology, and more specifically, relates to a method and device for obtaining the large-scale step response of a feed system. Background Technology

[0002] Exploring and mastering the response characteristics of CNC machine tool feed systems is fundamental to accurate servo parameter adjustment and precise feed system modeling. The step response reflects the dynamic response characteristics of the feed system, and its accuracy directly affects the accuracy of the adjusted servo parameters and the simulation capability of the established feed system model. Currently, the common engineering process for obtaining the step response of a feed system involves two steps:

[0003] Step 1: With the feed system in zero initial conditions, input a step signal into the system.

[0004] Step 2: Collect response data from the feeding system using a position detection device (optical ruler, motor encoder, etc.).

[0005] However, this method of obtaining the information has the following problems:

[0006] (1) The amplitude of the step response is limited. Step responses of different amplitudes can reflect the dynamic characteristics of the feed axis under different operating conditions, but due to the limitations of factors such as the maximum acceleration of the feed system and the current limit, existing methods cannot obtain step responses with large amplitudes. At the same time, due to the influence of the nonlinear friction force of the feed system, the shapes of step responses of different amplitudes are not exactly the same, so it is not possible to simply obtain step responses of different amplitudes by proportionally amplifying small-amplitude step responses.

[0007] (2) The accuracy of the step response is limited. Due to the limitation of the resolution of the position detection device, the sampled step response has quantization error, which directly affects the accuracy of the step response and thus affects the analysis of the dynamic response characteristics of the feed system.

[0008] Therefore, the step response obtained using existing methods has shortcomings in terms of accuracy and amplitude. Summary of the Invention

[0009] In view of the above-mentioned defects or improvement needs of the prior art, the present invention provides a method and device for obtaining the large-amplitude step response of a feeding system. The method connects a gradually changing acceleration process and a gradually changing deceleration process before and after the step signal, respectively, to amplify the step signal into a spliced ​​signal of multiple consecutive periodic step signals with different amplitudes, thereby avoiding the speed change caused by the large-amplitude step signal.

[0010] To achieve the above objectives, according to one aspect of the present invention, a method for obtaining the large-amplitude step response of a feed system is provided, the method comprising the following steps:

[0011] (1) An acceleration sequence and a deceleration sequence are connected before and after the target step signal to form an excitation signal;

[0012] (2) First, obtain the response data of the feeding system under the action of the excitation signal. The response data includes the response corresponding to n acceleration and deceleration sequence step signals. Then, arrange the responses corresponding to the n acceleration and deceleration sequence step signals in ascending order, and then iteratively solve according to the obtained sorting to obtain the target step response. Wherein, n is a positive integer.

[0013] Furthermore, assuming that the control frequency of the CNC system and the sampling frequency of the detection device are the same, both f, and the amplitude of the target step signal is apt. aim If n step signals of different amplitudes are arranged in ascending order to form an acceleration sequence, then the amplitude of each step signal is as follows:

[0014]

[0015] Furthermore, the acceleration of the accelerated sequence is:

[0016]

[0017] The deceleration sequence is obtained by reversing the acceleration sequence, and the acceleration of the deceleration sequence is a. dec =-a acc The amplitude of the deceleration sequence is:

[0018]

[0019] Furthermore, by connecting the acceleration sequence to the target step signal, and then connecting it to the deceleration sequence, a set of excitation signals with acceleration and deceleration processes is obtained:

[0020]

[0021] Furthermore, if the maximum acceleration of the feed system is a max Then the acceleration a during the acceleration and deceleration processes acc No more than a max Then n should satisfy:

[0022]

[0023] Furthermore, before inputting the excitation signal into the feeding system, the excitation signal is superimposed with the acceleration-uniform speed-deceleration excitation signal and then applied to the feeding system; subsequently, when collecting response data, the response corresponding to the acceleration-uniform speed-deceleration excitation signal is removed from the response data corresponding to the superimposed excitation signal to obtain the response data corresponding to the excitation signal.

[0024] Furthermore, the excitation signal is superimposed on the excitation signal during the uniform velocity phase.

[0025] Furthermore, an acceleration-uniform speed-deceleration excitation signal was set, in which the feed speed Fc during the uniform speed process enabled the feed system to avoid the nonlinear stage of friction.

[0026] The present invention also provides a system for obtaining the large-amplitude step response of a feed system. The system includes a memory and a processor. The memory stores a computer program, and the processor executes the computer program to perform the method for obtaining the large-amplitude step response of the feed system as described above.

[0027] The present invention also provides a computer-readable storage medium storing machine-executable instructions, which, when invoked and executed by a processor, cause the processor to implement the method for obtaining the large step response of the feed system as described above.

[0028] In summary, compared with the prior art, the method and device for obtaining the large-amplitude step response of the feed system provided by the present invention have the following advantages:

[0029] 1. The present invention connects a slowly varying acceleration sequence and a slowly varying deceleration sequence before and after the target step signal, respectively, to amplify the step signal into a spliced ​​signal of multiple consecutive periodic step signals with different amplitudes, thereby avoiding the speed change caused by the large-amplitude step signal.

[0030] 2. In acquiring response data, the present invention first superimposes the excitation signal with the acceleration-uniform speed-deceleration excitation signal, and then removes the response corresponding to the acceleration-uniform speed-deceleration excitation signal. This avoids frictional nonlinearity and ensures that the response of the step signal in the excitation signal remains consistent in different acceleration and acceleration processes.

[0031] 3. By changing the zero-state step response to a step response during acceleration and deceleration, the limitations of the maximum acceleration, speed, and current of the feed system are overcome. Under the condition that the mechanical conditions of the feed system are met, a step response of arbitrary amplitude can be obtained.

[0032] 4. The step response of the feed system obtained by this method has higher accuracy and the influence of quantization error is further reduced, which is of great significance for improving the accuracy of subsequent servo parameter tuning and feed system motion model calibration. Attached Figure Description

[0033] Figure 1 (a) and (b) in the diagram are schematic diagrams of the step signal and response of the feed system in the zero state, respectively.

[0034] Figure 2 (a) and (b) in the figure are amplitude diagrams of the acceleration and deceleration processes containing n step signals, respectively.

[0035] Figure 3 It is a schematic diagram of the excitation signal consisting of the acceleration process, the target step signal, and the deceleration process;

[0036] Figure 4 It is a schematic diagram of an excitation signal that includes n acceleration and deceleration processes;

[0037] Figure 5-1 This is a schematic diagram of the amplitude of the acceleration-uniform speed-deceleration excitation signal;

[0038] Figure 5-2 This is a velocity diagram of the acceleration-uniform-deceleration excitation signal;

[0039] Figure 6-1 This is a schematic diagram of the excitation signal (1);

[0040] Figure 6-2 This is a schematic diagram of the excitation signal (2);

[0041] Figure 7-11 (a) and (b) in the diagram are schematic diagrams of the acceleration and deceleration excitation signals and responses of the first group, respectively.

[0042] Figure 7-12 This is a schematic diagram of the acceleration and deceleration excitation signals and responses (real) in Group 1;

[0043] Figure 7-21 (a) and (b) in the diagram are schematic diagrams of the acceleration and deceleration excitation signals and responses in the second group, respectively.

[0044] Figure 7-22 (a) and (b) in the diagram are schematic diagrams of the acceleration and deceleration excitation signals and responses (real) in the second group, respectively.

[0045] Figure 7-31 (a) and (b) are schematic diagrams of the step responses extracted from the second group, respectively.

[0046] Figure 7-32 This is a schematic diagram of the actual step response extracted from group 2;

[0047] Figure 7-41 This is a schematic diagram of the target large step response (real).

[0048] Figure 8 This is a flowchart of a method for obtaining the large-amplitude step response of a feed system provided in an embodiment of the present invention. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be 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 illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0050] This invention provides a method and apparatus for obtaining a large-amplitude step response of a feed system. Due to factors such as the feed system's maximum acceleration limit and current limiting, the amplitude of the step response is restricted. Existing methods for obtaining the feed system's step response require inputting a step signal into the feed system at its initial zero state. If the amplitude of this step signal is too large, it will cause a significant velocity change. If it exceeds the feed system's maximum acceleration or current limiting, the signal's response will be restricted. Therefore, this invention intersperses a gradually changing acceleration process and a gradually changing deceleration process before and after the step signal, amplifying the step signal into a spliced ​​signal of multiple consecutive periods of step signals with different amplitudes, thereby avoiding the velocity changes caused by the large-amplitude step signal.

[0051] Furthermore, when acquiring the step response of the feed system using a position detection device, the quantization error caused by the upper limit of the detection device's resolution affects the accuracy of the acquired step response. Quantization error is an unavoidable error; its impact on the step response can only be reduced. For the same position detection device, the quantization error is fixed; therefore, increasing the amplitude of the step response can reduce the proportion of the quantization error in the step response, thereby reducing its influence. However, due to the aforementioned reasons, the amplitude of the step response is limited, thus limiting the solution to this problem. The present invention proposes a scheme that interleave acceleration and deceleration sequences before and after the step signal to obtain a step response with a larger amplitude, thereby reducing the interference caused by quantization error and improving the accuracy of the step response.

[0052] Please see Figure 1 , Figure 2 , Figure 3 and Figure 4 The acquisition method mainly includes the following steps:

[0053] Step 1: Connect acceleration and deceleration sequences before and after the target step signal to form an excitation signal.

[0054] The amplitude of the zero-state step response is constrained by the maximum acceleration limit and current limit of the feed system. To obtain a step response with a larger amplitude, an acceleration sequence and a deceleration sequence are connected before and after the step signal to form an excitation signal, thereby avoiding the high acceleration and velocity abrupt changes caused by the large amplitude step signal. After inputting the excitation signal into the feed system and sampling the response data, it is found that the target step response is mixed with the responses of n consecutive step signals with different amplitudes. It is necessary to know the responses of the n step signals with different amplitudes in order to isolate the target step response mixed in.

[0055] Consider solving for the target step response through iterative calculation. First, for the n step signals with different amplitudes, design acceleration and deceleration sequences with the same acceleration, and connect them before and after each step signal. The i-th acceleration sequence should contain i step signals with different amplitudes, and all i step signals should be included in the i-th acceleration / deceleration sequence. Given the first step response, the target step response can be obtained through n iterations, ultimately yielding an excitation signal containing n+1 acceleration / deceleration sequences.

[0056] Step two: First, obtain the response data of the feeding system under the excitation signal. The response data includes the responses corresponding to n acceleration / deceleration sequence step signals. Then, arrange the responses corresponding to the n acceleration / deceleration sequence step signals in ascending order, and iteratively solve according to the obtained sorting to obtain the target step response. Here, n is a positive integer.

[0057] Before solving for the large amplitude step response, the response of the feeding system under the input excitation signal is first obtained through the position detection device. The responses of the n acceleration and deceleration sequences are arranged in ascending order of amplitude. The solution is iteratively calculated according to the arrangement order. Finally, n step responses with different amplitudes can be obtained, where the nth step response is the target step response.

[0058] The step response of a feed system obtained using traditional methods is a zero-state response. The feed system needs to accelerate from 0 speed to the target speed in a very short time. If the target speed is large, it will exceed the maximum acceleration limit of the feed system, thus failing to obtain an ideal step response. To overcome this limitation, this invention designs an acceleration and deceleration strategy so that the step response is no longer obtained from the zero-state response. Instead, a smooth acceleration and deceleration process is added before and after the target step signal, ensuring that the feed system does not exceed its maximum acceleration limit. Therefore, the feed system can fully respond to step signals with large amplitude.

[0059] Acquiring the step response of a feed system requires a position measuring device. However, due to the limitations of its resolution, the step response data acquired by the position measuring device contains quantization errors. The magnitude of the quantization error is fixed and does not change with the amplitude of the step response; therefore, the larger the amplitude of the step response, the smaller the proportion of the quantization error. This invention allows for the acquisition of step responses with larger amplitudes, thus significantly reducing the interference of quantization errors on the step response and improving its accuracy.

[0060] Please see Figure 8 To provide a more detailed explanation of the present invention, the two main steps of the invention are described below with reference to specific embodiments:

[0061] S1, Determine the feed system excitation signal used to identify the large-amplitude step response.

[0062] If the amplitude of the step signal is large, the resulting acceleration may exceed the maximum acceleration limit of the feed system, thus making it unable to fully respond to the step signal.

[0063] Assuming the control frequency of the CNC system and the sampling frequency of the detection device are the same, both f, and the amplitude of the target step signal is apt. aim To address the sudden velocity changes caused by step signals in the feed system, this embodiment employs an acceleration sequence before and a deceleration sequence after the step signal. The resulting excitation signal can be obtained by combining step signals of different amplitudes. First, n step signals of different amplitudes are arranged in ascending order to form an acceleration sequence. The amplitude of each step signal is then as follows:

[0064]

[0065] The acceleration of the accelerated sequence is:

[0066]

[0067] The deceleration sequence is obtained by reversing the acceleration sequence, and the acceleration of the deceleration sequence is a. dec =-a acc The amplitude of the deceleration sequence is:

[0068]

[0069] Finally, as shown in the following formula, by connecting the acceleration sequence to the target step signal and then to the deceleration sequence, a set of excitation signals with acceleration and deceleration processes is obtained:

[0070]

[0071] If the maximum acceleration of the feed system is a maxThen the acceleration a during the acceleration and deceleration processes acc It should not exceed a max Then n should satisfy:

[0072]

[0073] Depend on Figure 2 and Figure 3 As can be seen, the large-amplitude step signal is mixed in with the other n step signals of different amplitudes. Therefore, the target large-amplitude step response is also mixed in with the n step responses and needs to be separated from them.

[0074] Consider obtaining the responses to n step signals sequentially through iterative calculation, ultimately separating the target amplitude step response from the excitation signal response data. First, for the n step signals of different amplitudes, design acceleration and deceleration sequences with the same acceleration, and connect them before and after each step signal. The accelerations of the acceleration and deceleration sequences are a and a0, respectively. acc and a dec The number of acceleration / deceleration sequences is n, where the m-th acceleration / deceleration sequence should contain m step signals with varying amplitudes. The amplitude of each step signal is:

[0075]

[0076] Since any step signal in the m-th acceleration / deceleration process is contained in the (m+1)-th acceleration / deceleration process, and the response of the 1st acceleration / deceleration process is known, the target step response can be extracted through n iterations. For example... Figure 4 As shown, the excitation signal contains n acceleration and deceleration processes.

[0077] Due to the influence of nonlinear friction in the feed system, the response characteristics of the same step signal vary at different stages of feed axis start-up and stop. That is, the response of a step signal in the m-th acceleration / deceleration sequence is not the same as that in the (m+1)-th acceleration / deceleration sequence. To ensure that the response of the same step signal in the above excitation signals remains consistent during different acceleration and deceleration processes, it is necessary to avoid frictional nonlinearity when setting the excitation signal. Therefore, in this embodiment, the excitation signal is superimposed with the acceleration-uniform speed-deceleration excitation signal before being input into the feed system; subsequently, when acquiring response data, the response corresponding to the acceleration-uniform speed-deceleration excitation signal is removed from the response data corresponding to the superimposed excitation signal to obtain the response data corresponding to the excitation signal. The excitation signal is superimposed with the excitation signal in the uniform speed stage.

[0078] like Figure 5-1 and Figure 5-2As shown, an acceleration-uniform speed-deceleration excitation signal is set. The feed speed Fc during the uniform speed process should ensure that the feed system avoids the nonlinear stage of friction. Then, the excitation signal containing n acceleration and deceleration processes is superimposed on the excitation signal for the uniform speed condition.

[0079] Then as Figure 6-1 and Figure 6-2 As shown, the obtained excitation signal includes two parts: excitation signal (1): an acceleration-uniform speed-deceleration excitation signal; excitation signal (2): a combination signal of the acceleration-uniform speed-deceleration excitation signal and an excitation signal containing n acceleration and deceleration processes.

[0080] S2, Acquisition of feed system response data and iterative solution of large-amplitude step response.

[0081] The obtained excitation signal is input into the feed system, and the response data is obtained by sampling. Since the response y2(t) of the excitation signal (2) contains the response y1(t) of the acceleration-uniform-deceleration excitation signal in (1), the response y3(t) of n acceleration and deceleration processes is obtained by the following calculation:

[0082] y3(t) = y2(t) - y1(t)

[0083] like Figure 4 The figure shows the calculated excitation signal containing n acceleration and deceleration processes, and its response is y3(t), where the response of the m-th acceleration and deceleration process is represented by y3. m (t). For example... Figure 7-11 and Figure 7-12 As shown, the first acceleration / deceleration process contains only one step response to be obtained, so it can be obtained directly. Figure 7-21 and Figure 7-22 As shown, the second acceleration / deceleration process involves two step responses to be obtained. Since one of the step responses has already been obtained through the first acceleration / deceleration process, the remaining step response can be extracted, as shown below. Figure 7-31 and Figure 7-32 As shown. Similarly, substituting the m step responses obtained from the first m acceleration / deceleration processes into the (m+1)th acceleration / deceleration process yields the (m+1)th step response. Repeating this iterative calculation n times yields the target step response.

[0084] Assume the time required for the step response to reach the steady-state response is T. stable t is the index of the step response, and the step response with the largest amplitude contained in the m-th acceleration / deceleration sequence is _response_. m The amplitude of the step response at time t is denoted as response. m t The iterative calculation process can be described as follows:

[0085]

[0086] Finally, the response is obtained after n iterations. n . Figure 7-41 The figure shows the step response with an amplitude of 0.176 mm, obtained by 50 iterations using this method on a test machine.

[0087] The present invention also provides a system for obtaining the large-amplitude step response of a feed system. The system includes a memory and a processor. The memory stores a computer program, and the processor executes the computer program to perform the method for obtaining the large-amplitude step response of the feed system as described above.

[0088] The present invention also provides a computer-readable storage medium storing machine-executable instructions, which, when invoked and executed by a processor, cause the processor to implement the method for obtaining the large step response of the feed system as described above.

[0089] Those skilled in the art will readily understand 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 within the scope of protection of the present invention.

Claims

1. A method for obtaining the large-amplitude step response of a feed system, characterized in that, The method includes the following steps: (1) Acceleration and deceleration sequences are connected before and after the target step signal respectively to form an excitation signal; (2) First, acquire the response data of the feed system under the action of the excitation signal, the response data including The response to each of the n acceleration / deceleration step signals is then arranged in ascending order, and the results are iteratively solved according to the obtained order to obtain the target step response; where n is a positive integer. Specifically, before inputting the excitation signal into the feeding system, the excitation signal is superimposed with the acceleration-uniform speed-deceleration excitation signal and then applied to the feeding system; subsequently, when collecting response data, the response corresponding to the acceleration-uniform speed-deceleration excitation signal is removed from the response data corresponding to the superimposed excitation signal to obtain the response data corresponding to the excitation signal.

2. The method for obtaining the large-amplitude step response of the feed system as described in claim 1, characterized in that: Assuming the control frequency of the CNC system and the sampling frequency of the detection device are the same, both are... The amplitude of the target step signal is If n step signals of different amplitudes are arranged in ascending order to form an acceleration sequence, then the amplitude of each step signal is as follows: 。 3. The method for obtaining the large-amplitude step response of the feed system as described in claim 2, characterized in that: The acceleration of the accelerated sequence is: The acceleration sequence is obtained by reversing the order of the acceleration sequences. The acceleration of the deceleration sequence is: The amplitude of the deceleration sequence is: 。 4. The method for obtaining the large-amplitude step response of the feed system as described in claim 3, characterized in that: By connecting the acceleration sequence to the target step signal, and then connecting it to the deceleration sequence, a set of excitation signals with acceleration and deceleration processes is obtained: 。 5. The method for obtaining the large-amplitude step response of the feed system as described in claim 4, characterized in that: If the maximum acceleration of the feed system is Then the acceleration during the acceleration process and the acceleration during the deceleration process No more than Then n should satisfy: 。 6. The method for obtaining the large-amplitude step response of the feed system as described in claim 1, characterized in that: The excitation signal is superimposed on the excitation signal during the uniform velocity phase.

7. The method for obtaining the large-amplitude step response of a feed system as described in claim 1, characterized in that: An acceleration-uniform speed-deceleration excitation signal was set, in which the feed rate Fc during the uniform speed process enabled the feed system to avoid the nonlinear stage of friction.

8. A system for obtaining the large-amplitude step response of a feed system, characterized in that: The system includes a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, it performs the method for obtaining the large step response of the feed system according to any one of claims 1-7.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores machine-executable instructions, which, when invoked and executed by a processor, cause the processor to implement the method for obtaining the large step response of the feed system according to any one of claims 1-7.

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