Active vibration isolation control method for cold atom gravimeter based on exponential disturbance observer

Abstract

The application provides a cold atom gravimeter active vibration isolation control method based on an exponential disturbance observer, and comprises the following steps: establishing a cold atom gravimeter active vibration isolation model; designing an exponential disturbance observer of the cold atom gravimeter to obtain an estimated value of vibration disturbance of the cold atom gravimeter; calculating an error between the estimated value and an actual value of the vibration disturbance of the cold atom gravimeter, and establishing an observation method of the error; and designing a control law of a mobile cold atom gravimeter active vibration isolation system. Through the establishment of the exponential disturbance observer, the actual value of the vibration disturbance can be compensated by the estimated value of the vibration disturbance, so that the vibration speed and the vibration displacement of the cold atom gravimeter active vibration isolation system rapidly converge, and the control precision of the cold atom gravimeter active vibration isolation system is effectively improved.

Description

Technical Field

[0001] This invention relates to the field of active vibration isolation technology for mobile cold atom gravimeters, and in particular to an active vibration isolation control method for cold atom gravimeters based on an exponential disturbance observer. Background Technology

[0002] Cold atom gravimeters are a novel type of quantum sensor that has developed rapidly over the past two decades. They utilize laser cooling, atomic interferometry, and other technologies to achieve high-precision, high-sensitivity measurements of gravitational acceleration. With the rapid engineering advancements in cold atom gravimeters, the development of mobile, high-precision cold atom gravimeters has become a major trend. Mobile cold atom gravimeters can be used in basic geological surveys, resource exploration and geophysical research, large submarine detection, underwater navigation, and deep-space microgravity detection.

[0003] In practical measurements, the accuracy of atomic gravity measurements is affected by ground vibration noise, Raman phase noise, and detection noise, among which vibration noise is the most significant factor affecting the measurement accuracy of atomic gravimeters. Currently, the natural frequency of commercially available passive vibration isolation platforms can be adjusted down to as low as 0.5 Hz, which can be used to isolate the influence of ground vibrations above 10 Hz on atomic gravimeters. However, atomic gravimeters are more sensitive to vibrations in the 0.1-10 Hz range, so a simple passive vibration isolation platform cannot meet the vibration isolation requirements of atomic gravimeters. Although the natural frequency of the entire passive vibration isolation platform can be adjusted, if the natural frequency is adjusted too low, the entire system will exhibit nonlinear effects. Ground vibrations near the passive isolation natural frequency are not only not suppressed, but actually increase on the original basis. Therefore, an active vibration isolation system needs to be introduced to suppress vibrations in this frequency band. However, existing active vibration isolation systems are affected by a large number of uncertainties, and current active vibration isolation control methods do not consider the problem of suppressing low-frequency ground vibrations under the background of external disturbances and uncertain system models, resulting in low control accuracy of the active vibration isolation system for cold atomic gravimeters. Summary of the Invention

[0004] This invention discloses an active vibration isolation control method for cold atom gravimeters based on an exponential disturbance observer. It solves the problem that current active vibration isolation methods for cold atom gravimeters do not consider the suppression of low-frequency ground vibrations under the background of external disturbances and system model uncertainty, resulting in low control accuracy of the active vibration isolation system for cold atom gravimeters. By establishing a control method based on an exponential disturbance observer, the vibration velocity and vibration displacement of the active vibration isolation system of the cold atom gravimeter converge rapidly, thereby improving the control accuracy of the active vibration isolation system of the cold atom gravimeter.

[0005] To achieve the above objectives, the technical solution of the present invention is specifically implemented as follows:

[0006] This invention discloses an active vibration isolation control method for a cold atom gravimeter based on an exponential disturbance observer, comprising the following steps:

[0007] Establish an active vibration isolation model for a cold atom gravimeter;

[0008] Design an exponential disturbance observer for a cold atom gravimeter to obtain an estimate of the vibration disturbance of the cold atom gravimeter;

[0009] The error between the estimated and actual values ​​of vibration interference from the cold atom gravimeter is determined, and a method for observing this error is established.

[0010] Design the control law for the active vibration isolation system of a mobile cold atom gravimeter.

[0011] Furthermore, the specific implementation of the active vibration isolation model for the cold atom gravimeter is as follows:

[0012]

[0013] Where ξ0 is the system damping coefficient, ω0 is the system natural frequency, F is the force generated by the voice coil motor, and x is the vibration displacement of the Raman mirror. Let be the vibration velocity of the Raman mirror. Let y be the vibration acceleration of the Raman mirror, and y be the ground vibration displacement. Ground vibration velocity, u is the controller input, K VC Y is the current gain coefficient of the voice coil motor. VC Where is the voltage-to-current gain coefficient, and m is the mass of the Raman mirror;

[0014] Define vibration disturbances in cold atom gravimeters The active vibration isolation model of the cold atom gravimeter was obtained as follows:

[0015]

[0016] Furthermore, the specific implementation of the cold atom gravimeter exponential interference observer is as follows:

[0017] According to equation (2), the vibration interference of the cold atom gravimeter is obtained:

[0018]

[0019] Obtain estimates of vibration disturbances from the cold atom gravimeter:

[0020]

[0021] in, This is an estimate of the vibration disturbance d. for The derivative of , where K is the gain coefficient and K > 0;

[0022] Substituting equation (3) into equation (4), we get:

[0023]

[0024] Define the auxiliary parameter vector:

[0025]

[0026] The derivative expression for the auxiliary parameter vector is:

[0027]

[0028] The designed cold atom gravimeter exponential interference observer is as follows:

[0029]

[0030] Furthermore, the error between the estimated and actual values ​​of the vibration disturbance of the cold atom gravimeter is calculated, and the specific implementation of this error observation method is established as follows:

[0031] The expression for the error between the estimated and actual values ​​of vibration interference from the cold atom gravimeter is as follows:

[0032]

[0033] For slow disturbances, assuming d = 0, the derivative expression for the error between the estimated and actual values ​​of vibration disturbances from the cold atom gravimeter is:

[0034]

[0035] Therefore, the equation for the error between the estimated and actual values ​​of vibration interference from the cold atom gravimeter is:

[0036]

[0037] The solution to equation (11) is:

[0038]

[0039] in, The error between the estimated and actual values ​​of vibration interference from the cold atom gravimeter The initial value of is given by , where t is time, exp is the natural constant, e is an exponential function with base e, and K is the gain coefficient.

[0040] Furthermore, the specific implementation of the control law for the active vibration isolation system of the cold atom gravimeter is as follows:

[0041] Define the expected value of the vibration displacement as x 1d Tracking error e = x 1d-x, then the control law for designing the active vibration isolation system of the cold atom gravimeter is:

[0042]

[0043] in, Let α1 and α2 be the derivative of the tracking error e, and let α1 and α2 be the gain coefficients and positive constants.

[0044] Beneficial technical effects:

[0045] This invention discloses an active vibration isolation control method for a cold atom gravimeter based on an exponential disturbance observer, comprising the following steps: establishing an active vibration isolation model for the cold atom gravimeter; designing an exponential disturbance observer for the cold atom gravimeter to obtain an estimate of the vibration disturbance of the cold atom gravimeter; calculating the error between the estimated and actual values ​​of the vibration disturbance of the cold atom gravimeter and establishing an observation method for this error; designing a control law for the active vibration isolation system of the moving cold atom gravimeter. This control method, by establishing an exponential disturbance observer, can compensate for the actual value of the vibration disturbance with the estimated value of the vibration disturbance, thereby rapidly converging the vibration velocity and vibration displacement of the active vibration isolation system of the cold atom gravimeter, effectively improving the control accuracy of the active vibration isolation system of the cold atom gravimeter. Attached Figure Description

[0046] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below.

[0047] Figure 1 This is a flowchart illustrating the steps of the active vibration isolation method for a cold atom gravimeter based on an exponential interference observer as described in this invention.

[0048] Figure 2 When the ground vibration frequency is 0.2Hz, the vibration displacement suppression effect of the active vibration isolation control method of the cold atom gravimeter based on the exponential interference observer described in this invention is compared with that of the PID control method.

[0049] Figure 3 When the ground vibration frequency is 0.2Hz, the vibration velocity suppression effect of the active vibration isolation control method of the cold atom gravimeter based on the exponential interference observer described in this invention is compared with that of the PID control method.

[0050] Figure 4 When the ground vibration frequency is 0.5Hz, the vibration displacement suppression effect of the active vibration isolation control method of the cold atom gravimeter based on the exponential interference observer described in this invention is compared with that of the PID control method.

[0051] Figure 5When the ground vibration frequency is 0.5Hz, the vibration velocity suppression effect of the active vibration isolation control method of the cold atom gravimeter based on the exponential interference observer described in this invention is compared with that of the PID control method.

[0052] Figure 6 When the ground vibration frequency is 2Hz, the active vibration isolation control method of the cold atom gravimeter based on the exponential interference observer and the PID control method described in this invention are compared in terms of vibration displacement suppression effect.

[0053] Figure 7 When the ground vibration frequency is 2Hz, a comparison of the vibration velocity suppression effects of the active vibration isolation control method for cold atom gravimeter based on exponential interference observer and the PID control method described in this invention is presented.

[0054] Figure 8 A comparison of the vibration displacement suppression effects of the active vibration isolation control method for cold atom gravimeter based on exponential interference observer and the PID control method described in this invention is presented when the ground vibration frequency is 5Hz.

[0055] Figure 9 When the ground vibration frequency is 5Hz, the active vibration isolation control method of the cold atom gravimeter based on the exponential interference observer and the PID control method described in this invention are compared to the vibration velocity suppression effect. Detailed Implementation

[0056] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0057] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0058] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0059] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0060] This invention discloses an active vibration isolation control method for a cold atom gravimeter based on an exponential disturbance observer. See [link to relevant documentation]. Figure 1 Specifically, it includes the following steps:

[0061] S1: Establish an active vibration isolation model for a cold atom gravimeter;

[0062] Specifically, the implementation of the active vibration isolation model for the cold atom gravimeter is as follows:

[0063]

[0064] Where ξ0 is the system damping coefficient, ω0 is the system natural frequency, F is the force generated by the voice coil motor, and x is the vibration displacement of the Raman mirror. Let be the vibration velocity of the Raman mirror. Let y be the vibration acceleration of the Raman mirror, and y be the ground vibration displacement. Ground vibration velocity, u is the controller input, K VC Y is the current gain coefficient of the voice coil motor. VC Where is the voltage-to-current gain coefficient, and m is the mass of the Raman mirror;

[0065] Define vibration disturbances in cold atom gravimeters The active vibration isolation model of the cold atom gravimeter was obtained as follows:

[0066]

[0067] S2: Design an exponential disturbance observer for the cold atom gravimeter to obtain an estimate of the vibration disturbance of the cold atom gravimeter;

[0068] It is important to understand that the basic idea behind the observer design in this invention is to correct the estimated value using the difference between the estimated output and the actual output.

[0069] Specifically, the implementation of the cold atom gravimeter exponential interference observer is as follows:

[0070] According to equation (2), the vibration interference of the cold atom gravimeter is obtained:

[0071]

[0072] Obtain estimates of vibration disturbances from the cold atom gravimeter:

[0073]

[0074] in, This is an estimate of the vibration disturbance d. for The derivative of , where K is the gain coefficient and K > 0;

[0075] Substituting equation (3) into equation (4), we get:

[0076]

[0077] Define the auxiliary parameter vector:

[0078]

[0079] The derivative expression for the auxiliary parameter vector is:

[0080]

[0081] The designed cold atom gravimeter exponential interference observer is as follows:

[0082]

[0083] S3: Calculate the error between the estimated and actual values ​​of vibration interference from the cold atom gravimeter, and establish a method for observing this error;

[0084] The error between the estimated and actual values ​​of vibration disturbance from the cold atom gravimeter is calculated, and the specific implementation of the error observation method is established as follows:

[0085] The expression for the error between the estimated and actual values ​​of vibration interference from the cold atom gravimeter is as follows:

[0086]

[0087] For slow disturbances, assuming d = 0, the derivative expression for the error between the estimated and actual values ​​of vibration disturbances from the cold atom gravimeter is:

[0088]

[0089] Therefore, the equation for the error between the estimated and actual values ​​of vibration interference from the cold atom gravimeter is:

[0090]

[0091] The solution to equation (11) is:

[0092]

[0093] in, The error between the estimated and actual values ​​of vibration interference from the cold atom gravimeter The initial value of is given by , where t is time, exp is the natural constant, e is an exponential function with base e, and K is the gain coefficient.

[0094] S4: Design the control law for the active vibration isolation system of the cold atom gravimeter.

[0095] Specifically, the implementation of the control law for the active vibration isolation system of the cold atom gravimeter is as follows:

[0096] Define the expected value of the vibration displacement as x 1d Tracking error e = x 1d -x, then the control law for designing the active vibration isolation system of the cold atom gravimeter is:

[0097]

[0098] in, Let α1 and α2 be the derivative of the tracking error e, and let α1 and α2 be the gain coefficients and positive constants.

[0099] The following simulation experiment compares the active vibration isolation control method for cold atom gravimeters based on exponential disturbance observers disclosed in this invention with the traditional PID control method, verifying that the active vibration isolation control method for cold atom gravimeters based on exponential disturbance observers disclosed in this invention can enable the vibration velocity and vibration displacement of the active vibration isolation system of cold atom gravimeters to converge rapidly.

[0100] As an embodiment of the present invention, the experimental simulation parameters for an active vibration isolation method for a cold atom gravimeter based on an exponential disturbance observer disclosed in the present invention are set as follows:

[0101] Set the system damping coefficient ξ0 = 0.1 N·s·m -1 The system's natural frequency ω0 = 4.396 rad, and the voice coil motor current gain coefficient K VC =0.1V·A -1 Voltage-to-current gain coefficient Y VC =7.6 N·A -1The mass of the Raman mirror is m = 10 kg; the gain parameter K = 50000, the gain parameter α1 = 800, and the gain parameter α2 = 500. Compared with the traditional PID control method, the PID control law parameters of the cold atom gravimeter active vibration isolation system are: proportional coefficient P = 10, integral time T... i =20 and differential time T d =20.

[0102] The active vibration isolation method for cold atom gravimeters based on an exponential disturbance observer disclosed in this invention enables the vibration velocity and displacement of the active vibration isolation system of a mobile cold atom gravimeter to converge rapidly, greatly improving the control accuracy of the active vibration isolation system of the mobile cold atom gravimeter. Figures 2-9 The figure shows a comparison between the active vibration isolation method for cold atom gravimeters based on an exponential disturbance observer disclosed in this invention and the traditional PID control method at various vibration frequencies. As can be seen from the figure, the vibration displacement controlled by the active vibration isolation method for cold atom gravimeters based on an exponential disturbance observer disclosed in this invention is significantly smaller than that controlled by the PID control method. Furthermore, the vibration velocity controlled by the active vibration isolation method for cold atom gravimeters based on an exponential disturbance observer disclosed in this invention is significantly smaller than that controlled by the PID control method. Therefore, it can be seen that the control effect of the active vibration isolation method for cold atom gravimeters based on an exponential disturbance observer disclosed in this invention far surpasses that of the traditional PID control method.

[0103] The active vibration isolation method for cold atom gravimeters disclosed in this invention, based on an exponential disturbance observer, solves the problem of low control accuracy of the active vibration isolation system for cold atom gravimeters due to the lack of consideration for low-frequency ground vibration suppression under the background of external disturbances and system model uncertainty in current active vibration isolation methods for cold atom gravimeters. By establishing an exponential disturbance observer, the estimated value of the vibration disturbance can be used to compensate for the actual value of the vibration disturbance, so that the vibration velocity and vibration displacement of the active vibration isolation system of the cold atom gravimeter converge rapidly, effectively improving the control accuracy of the active vibration isolation system of the cold atom gravimeter.

[0104] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0105] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0106] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0107] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0108] The above embodiments are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. An active vibration isolation control method for a cold atom gravimeter based on an exponential disturbance observer, characterized in that, Includes the following steps: Establish an active vibration isolation model for a cold atom gravimeter; The specific implementation of the active vibration isolation model for the cold atom gravimeter is as follows: （1） in, The system damping coefficient is... The natural frequency of the system. This represents the vibrational displacement of the Raman mirror. Let be the vibration velocity of the Raman mirror. The vibration acceleration of the Raman mirror. This represents ground vibration displacement. Ground vibration velocity, For controller input, This is the current gain coefficient of the voice coil motor. This is the voltage-to-current gain coefficient. The mass of the Raman mirror; Define vibration disturbances in cold atom gravimeters The active vibration isolation model of the cold atom gravimeter was obtained as follows: （2）； Design an exponential disturbance observer for a cold atom gravimeter to obtain an estimate of the vibration disturbance of the cold atom gravimeter; The specific implementation of the cold atom gravimeter exponential interference observer is as follows: According to equation (2), the vibration interference of the cold atom gravimeter is obtained: （3） Obtain estimates of vibration disturbances from the cold atom gravimeter: （4） in, For vibration interference The estimated value, for The derivative of The gain coefficient and ; Substituting equation (3) into equation (4), we get: （5） Define the auxiliary parameter vector: （6） The derivative expression for the auxiliary parameter vector is: （7） The designed cold atom gravimeter exponential interference observer is as follows: （8）； The error between the estimated and actual values ​​of vibration interference from the cold atom gravimeter is determined, and a method for observing this error is established. The error between the estimated and actual values ​​of vibration disturbance from the cold atom gravimeter is calculated, and the specific implementation of the error observation method is established as follows: The expression for the error between the estimated and actual values ​​of vibration interference from the cold atom gravimeter is as follows: （9） For slow interference, assume Then, the derivative expression for the error between the estimated and actual values ​​of the vibration disturbance of the cold atom gravimeter is: （10） ， Therefore, the equation for the error between the estimated and actual values ​​of vibration interference from the cold atom gravimeter is: （11） The solution to equation (11) is: （12） in, The error between the estimated and actual values ​​of vibration interference from the cold atom gravimeter initial value, For time, It is an exponential function with the natural constant e as its base. This is the gain coefficient; Design the control law for the active vibration isolation system of a mobile cold atom gravimeter; The specific implementation of the control law for the active vibration isolation system of the Licheng Atomic Gravimeter is as follows: The expected value of the vibration displacement is defined as follows: Tracking error The control law for designing the active vibration isolation system of the cold atom gravimeter is as follows: （13） in, For tracking error The derivative of It is the gain coefficient and is a positive constant.

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