Atomic gravity dynamic measurement stable platform and method

Abstract

This invention discloses a dynamic measurement stabilization platform for atomic gravity. An outer frame is housed within a supporting frame, and an inner frame is housed within the outer frame. A mounting ring is housed within the inner frame and fixed to the atomic gravimeter's fall chamber. The fixing part of an inner frame torque motor is mounted on the inner frame, and the rotation shaft of the inner frame torque motor drives the mounting ring to rotate. Similarly, the fixing part of an outer frame torque motor is mounted on the outer frame, and the rotation shaft of the outer frame torque motor drives the inner frame to rotate. This invention also discloses a dynamic measurement stabilization method for atomic gravity. The invention uses suspension ropes and air dampers to provide damping and buffering for the outer frame, inner frame, mounting ring, and atomic gravimeter's fall chamber as a whole during swaying. By driving the outer and inner frame torque motors, the spatial state of the atomic gravimeter's fall chamber is adjusted, ensuring that the central axis of the atomic gravimeter's fall chamber is stabilized in a vertical state.

Description

Technical Field

[0001] This invention relates to the field of dynamic atomic gravity measurement technology, specifically to a stable platform for dynamic atomic gravity measurement, and also to dynamic atomic gravity measurement stabilization. Background Technology

[0002] Atomic gravimeter dynamic measurement technology, as a novel high-precision dynamic measurement method, represents the forefront of precision gravity measurement. Unlike classic falling absolute gravimeters, atomic gravimeters use cold atomic clusters composed of neutral atoms instead of traditional mechanical mass blocks as the detection material, eliminating mechanical fatigue issues and allowing for continuous long-term measurement of gravitational acceleration. It offers better system robustness, higher operating frequency, and higher measurement sensitivity, and is also more suitable for compact integrated designs. Therefore, atomic gravimeters are ideally suited for dynamic measurements.

[0003] To date, high-precision atomic gravity measurements have only been performed in undisturbed static environments, with few reports of accurate measurements conducted on ships or aircraft. A key reason is that under dynamic conditions, cold atomic clusters are sensitive not only to gravitational acceleration but also to carrier acceleration. Horizontal acceleration of the carrier can cause the cold atomic clusters to move laterally beyond the Raman beam range, preventing interference. Even if the cold atomic clusters remain within the Raman beam range, this lateral movement introduces significant phase-shift noise, resulting in substantial systematic errors and a significant reduction in instrument accuracy. Conversely, vertical acceleration of the carrier can easily cause the instrument's active and passive vibration damping platforms to deviate from their equilibrium positions, losing their damping function. Vertical acceleration and vibration noise are then directly transmitted to the Raman mirror, severely reducing the instrument's sensitivity. Simultaneously, according to the equivalence principle, carrier acceleration and gravity are coupled, generating substantial measurement errors. Therefore, a core issue in precise dynamic atomic gravity measurement is the suppression and separation of carrier acceleration. A stable platform is a crucial piece of equipment for solving this problem. Summary of the Invention

[0004] The purpose of this invention is to address the aforementioned problems in the prior art by providing a stable platform for dynamic measurement of atomic gravity, and also to provide a stable method for dynamic measurement of atomic gravity.

[0005] The above-mentioned objective of the present invention is achieved through the following technical solution:

[0006] A dynamic measurement stabilization platform for atomic gravity includes a support frame, an outer frame inside the support frame, an inner frame inside the outer frame, and a mounting ring inside the inner frame. The mounting ring is fitted and fixed onto the falling chamber of the atomic gravimeter.

[0007] Two inner rotating shafts are fixed on the mounting ring and are located on the rotation axis of the mounting ring. The two inner rotating shafts are movably mounted on the inner frame. One of the inner rotating shafts is connected to the rotating shaft of the inner frame torque motor. The fixing part of the inner frame torque motor is set on the inner frame. An inner frame angle sensor is set on the inner frame to monitor the rotation angle of the inner frame torque motor's rotating shaft relative to the inner frame.

[0008] Two outer rotating shafts are fixed on the inner frame and located on the rotation axis of the inner frame. The two outer rotating shafts are movably mounted on the outer frame. One of the outer rotating shafts is connected to the rotating shaft of the outer frame torque motor. The fixing part of the outer frame torque motor is mounted on the outer frame. An outer frame angle sensor is installed on the outer frame to monitor the rotation angle of the outer frame torque motor's rotating shaft relative to the outer frame.

[0009] The bottom of the outer frame is connected to the top of the buffer support, the bottom of which is located at the bottom of the support frame. The top of the outer frame is connected to the top of the support frame via suspension ropes.

[0010] The mounting ring is equipped with two orthogonal accelerometers and two orthogonal fiber optic gyroscopes.

[0011] As described above, the inner frame, outer frame, atomic gravimeter falling cavity, and suspension rope constitute the first-order pendulum; the atomic gravimeter falling cavity, inner frame, and outer frame constitute the second-order pendulum. The first-order and second-order pendulums together form a second-order pendulum. When the mounting ring is in a horizontal state, the central axis of the atomic gravimeter falling cavity is in a vertical state. The axes of the inner and outer rotation axes are perpendicular to each other on the horizontal plane. The axial directions of the inner and outer rotation axes are the second and first horizontal directions, respectively. The axes of the inner and outer rotation axes intersect at the center of mass of the atomic gravimeter falling cavity. Two accelerometers are used to detect the horizontal deviation signals of the mounting ring in the first and second horizontal directions, respectively. Two gyroscopes are used to detect the angular rates of the mounting ring in the first and second horizontal directions, respectively.

[0012] As described above, the top of the outer frame is connected to the top of the support frame via suspension ropes.

[0013] As described above, the buffer support includes a buffer support unit connected to the bottom of each side frame of the outer frame. Each buffer support unit includes two air dampers distributed in a V-shape. The telescopic ends of the two air dampers of each buffer support unit are hinged to the bottom of the corresponding side frame of the outer frame. The fixed ends of the two air dampers of the buffer support unit are hinged to the vibration isolation pad, which is located at the bottom of the support frame.

[0014] A stable method for dynamic measurement of atomic gravity includes the following steps:

[0015] Step 1: Using a gyroscope, obtain the first angular rate signal and the second angular rate signal of the mounting ring in the first horizontal direction and the second horizontal direction. Convert the first angular rate signal and the second angular rate signal into electrical signals and transmit them to the digital control circuit after gain amplification.

[0016] The accelerometer obtains the first horizontal deviation signal and the second horizontal deviation signal of the mounting ring in the first and second horizontal directions, and transmits them to the digital control circuit after gain amplification.

[0017] The first rotation angle signal is obtained by the inner frame corner sensor, and the second rotation angle signal is obtained by the outer frame corner sensor. Then, the first rotation angle signal and the second rotation angle signal are amplified and transmitted to the digital control circuit.

[0018] Step 2: Calculate the first horizontal deviation angular rate of the first horizontal deviation signal corresponding to the first angular rate signal and the second angular rate signal, and differentiate the first rotation angle signal and the second rotation angle signal to obtain the first rotation angular rate and the second rotation angular rate.

[0019] Step 3: Based on the first angular rate signal, the first horizontal deviation angular rate, and the first rotational angular rate, calculate the first optimal control signal using the H∞ control algorithm.

[0020] Based on the second angular rate signal, the second horizontal deviation angular rate, and the second rotational angular rate, the second optimal control signal is calculated using the H∞ control algorithm.

[0021] The first and second optimal control signals are then amplified by the corresponding power amplifiers and sent to the corresponding pulse code modulation modules, which convert them into corresponding pulse code modulation sequences and feed them back to the inner frame torque motor and the outer frame torque motor, respectively. The inner frame torque motor and the outer frame torque motor rotate at a certain rate and response time according to the first and second optimal control signals, respectively.

[0022] As described above, the first horizontal deviation angular rate of the first horizontal deviation signal in step 2 is calculated based on the following formula:

[0023]

[0024] In the above formula: when calculating the first horizontal deviation angular rate: θ is the horizontal deviation of the support frame in the first horizontal direction, and (θ+x" / g) is the first horizontal deviation signal obtained in step 1;

[0025] When calculating the second horizontal deviation angular rate: θ is the horizontal deviation of the support frame in the second horizontal direction, and (θ+x" / g) is the second horizontal deviation signal obtained in step 1;

[0026] ω2 is the natural frequency of the second-order pendulum. l2 is the distance from the inner rotation axis to the center of mass of the falling cavity of the atomic gravimeter, θ' is the first derivative of θ, g is the gravitational acceleration, x" is the horizontal acceleration, ζ is the damping coefficient, and g is the gravitational acceleration.

[0027] As mentioned above, the H∞ control algorithm in step 3 is based on the following formula:

[0028]

[0029] S(s)=A(I+K W W(s)K R ) -1

[0030] T(s) = BK W W(s)K R (I+K W W(s)K R ) -1

[0031] R(s) = CK W W(s)(I+K W W(s)K R ) -1

[0032] When calculating the first optimal control signal, S(s) is a function that processes the first horizontal deviation angular rate, T(s) is a function that processes the first angular rate signal, R(s) is a function that processes the first rotational angular rate, A is the Laplace transform function of the first horizontal deviation angular rate, B is the Laplace transform function of the first angular rate signal, C is the Laplace transform function of the first rotational angular rate, and K... W K is the output gain coefficient of the gyroscope that measures the first angular rate signal. T K is the torque coefficient of the inner frame torque motor. R It is the output gain coefficient of the inner frame corner sensor;

[0033] When calculating the second optimal control signal, S(s) is a function processing the second horizontal deviation angular rate, T(s) is a function processing the second angular rate signal, and R(s) is a function processing the second rotational angular rate. A is the Laplace transform function of the second horizontal deviation angular rate, B is the Laplace transform function of the second angular rate signal, C is the Laplace transform function of the second rotational angular rate, and K... W K is the output gain coefficient of the gyroscope that measures the second angular rate signal. T It is the torque coefficient of the outer frame torque motor, K. R It is the output gain coefficient of the inner frame corner sensor;

[0034] s is the Laplace operator notation, and W is the performance bound function. S (s) is the weight function of the function S(s); the object uncertainty bound function W T (s) is the weight function of function T(s); the boundary function W R (s) is the weight function of the function R(s).

[0035] I is a unit symmetric matrix.

[0036] Calculate the optimal controller W(s) for the inner frame torque motor and the outer frame torque motor that satisfy the formula of the above H∞ control algorithm.

[0037] Based on the optimal controller W(s) corresponding to the inner frame torque motor and the outer frame torque motor, the functions S(s), T(s), and R(s) are recalculated respectively, and the functions S(s), T(s), and R(s) are superimposed to obtain the first optimal control signal for controlling the inner frame torque motor and the second optimal control signal for controlling the outer frame torque motor.

[0038] Compared with the prior art, the present invention has the following advantages:

[0039] 1. The suspension ropes and air dampers provide damping and buffering for the outer frame, inner frame, mounting ring, and atomic gravimeter drop chamber as a whole during swaying.

[0040] 2. By driving the outer frame torque motor and the inner frame torque motor, the spatial state of the falling chamber of the atomic gravimeter is adjusted so that the central axis of the falling chamber of the atomic gravimeter is stabilized in a vertical state. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the structure of the present invention;

[0042] Figure 2 This is a top view of the structure of the present invention.

[0043] In the diagram: 1-Support frame; 2-Outer frame; 3-Inner frame; 4-Mounting ring; 5-Atomic gravimeter falling cavity; 6-Inner frame torque motor; 7-Inner frame angle sensor; 8-Outer frame torque motor; 9-Outer frame angle sensor; 10-Suspension rope; 11-Buffer support unit; 12-Air damper; 13-Vibration isolation pad; 14-Inner rotation shaft; 15-Outer rotation shaft; 16-Four-column support hollow frame; 17-Upper support plate; 18-Lower support plate; 19-Accelerometer; 20-Gyroscope. Detailed Implementation

[0044] To facilitate understanding and implementation of the present invention by those skilled in the art, the present invention will be further described in detail below with reference to examples. It should be understood that the embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0045] Example 1:

[0046] like Figure 1 As shown, the dynamic measurement stabilization platform for atomic gravity includes a square support frame 1, a square annular outer frame 2 inside the support frame 1, a square annular inner frame 3 inside the outer frame 2, and a mounting ring 4 inside the inner frame 3. The mounting ring 4 is fitted and fixed onto the falling chamber 5 of the atomic gravimeter.

[0047] Two inner rotating shafts 14 are fixed on the mounting ring 4. The two inner rotating shafts 14 are located on the rotation axis of the mounting ring 4, and the straight line connecting the two inner rotating shafts 14 is the rotation axis of the mounting ring 4 and passes through the center of the mounting ring 4. The two inner rotating shafts 14 are movably mounted on the inner frame 3. Preferably, the inner rotating shafts 14 are mounted on the inner frame 3 through bearings. One of the inner rotating shafts 14 is connected to the rotating shaft of the inner frame torque motor 6. The fixed part of the inner frame torque motor 6 is mounted on the inner frame 3. When the rotating shaft of the inner frame torque motor 6 rotates, it can drive the mounting ring 4 to rotate, thereby driving the atomic gravimeter's falling chamber 5 to rotate. The inner frame 3 is provided with an inner frame angle sensor 7 for monitoring the rotation angle of the rotating shaft of the inner frame torque motor 6 relative to the inner frame 3.

[0048] Two outer rotating shafts 15 are fixed on the inner frame 3. The two outer rotating shafts 15 are located on the rotation axis of the inner frame 3. Preferably, the two outer rotating shafts 15 are respectively set at the center of the two opposite side frames of the inner frame 3. The two outer rotating shafts 15 are movably set on the outer frame 2. Preferably, the outer rotating shafts 15 are set on the outer frame 2 through bearings. One of the outer rotating shafts 15 is connected to the rotating shaft of the outer frame torque motor 8. The fixed part of the outer frame torque motor 8 is set on the outer frame 2. When the rotating shaft of the outer frame torque motor 8 rotates, it can drive the inner frame 3 to rotate, thereby driving the mounting ring 4 and the atomic gravimeter falling cavity 5 to rotate. The outer frame 2 is provided with an outer frame angle sensor 9 for monitoring the rotation angle of the rotating shaft of the outer frame torque motor 8 relative to the outer frame 2. By driving the rotation direction and rotation angle of the rotating shafts of the outer frame torque motor 8 and the inner frame torque motor 6, the spatial state of the atomic gravimeter falling cavity 5 is adjusted so that the central axis of the atomic gravimeter falling cavity 5 is stabilized in a vertical state.

[0049] The bottom of the outer frame 2 is connected to the top of the buffer support, and the bottom of the buffer support is located at the bottom of the support frame 1. The rotation axis of the mounting ring 4 and the rotation axis of the inner frame 3 are orthogonal and located in the same plane. The center of gravity of the falling chamber 5 of the atomic gravimeter is located at the point where the rotation axis of the mounting ring 4 and the rotation axis of the inner frame 3 intersect.

[0050] The top of the outer frame 2 is connected to the top of the supporting frame 1 via suspension ropes. There are four suspension ropes, with the bottom ends of the four ropes connected to the four apex corners of the outer frame 2 and the top ends of the four ropes connected to the top of the supporting frame 1. The suspension ropes provide damping and cushioning for the outer frame 2, inner frame 3, mounting ring 4, and atomic gravimeter drop chamber 5 as a whole during swaying.

[0051] The mounting ring 4 is equipped with accelerometers and fiber optic gyroscopes. Two sets of accelerometers and two sets of fiber optic gyroscopes are orthogonally distributed. The accelerometers and fiber optic gyroscopes are used to measure relevant state parameters of the falling cavity 5 of the atomic gravimeter.

[0052] The buffer support includes buffer support units 11 connected to the bottom of each side frame of the outer frame 2. Each buffer support unit 11 includes two air dampers 12 arranged in a V-shape. In this embodiment, there are four buffer support units 11 and a total of eight air dampers 12. The telescopic ends of the two air dampers 12 of each buffer support unit 11 are hinged to the bottom of the corresponding side frame of the outer frame 2. The fixed ends of the two air dampers 12 of the buffer support unit are hinged to the vibration isolation pads 13, which are located at the bottom of the support frame 1. The air dampers 12 provide damping buffering for the outer frame 2, inner frame 3, mounting ring 4, and atomic gravimeter drop chamber 5 during shaking.

[0053] The support frame 1 includes a four-column support hollow frame 16, with an upper support plate 17 covering the top of the four-column support hollow frame 16 and a lower support plate 18 on the bottom surface of the four-column support hollow frame 16. The top of the outer frame 2 is connected to the upper support plate 17 via suspension ropes, and the vibration isolation pad 13 is installed on the lower support plate 18.

[0054] Example 2:

[0055] The atomic gravity dynamic measurement stabilization method utilizes the atomic gravity dynamic measurement stabilization device described in Example 1:

[0056] The inner frame 3, outer frame 2, atomic gravimeter falling cavity 5, and suspension rope 10 form the first-order pendulum; the atomic gravimeter falling cavity 5, inner frame 3, and outer frame 2 form the second-order pendulum, and the first-order pendulum and the second-order pendulum together form a second-order pendulum.

[0057] The natural frequency ω1 of the first-order pendulum is based on the following formula:

[0058]

[0059] Where l1 is the length of the suspension rope 10, and g is the acceleration due to gravity.

[0060] The natural frequency ω2 of the second-order pendulum is based on the following formula:

[0061]

[0062] Where l2 is the distance from the inner rotation axis 14 to the center of mass of the falling cavity 5 of the atomic gravimeter.

[0063] The natural period T of the second-order pendulum is based on the following formula:

[0064]

[0065] The natural frequency ω of the second-order pendulum is based on the following formula:

[0066]

[0067] Where τ is the damping coefficient of the first-stage pendulum, m1 is the sum of the masses of the inner frame 3 and the outer frame 2, and m2 is the mass of the falling cavity 5 of the atomic gravimeter.

[0068] As described in Example 1, refer to Figure 2 An accelerometer 19 and a gyroscope 20 are installed on the mounting ring 4. When the mounting ring 4 is in a horizontal state, the central axis of the atomic gravimeter's falling cavity 5 is in a vertical state. The axis of the inner rotation axis 14 and the axis of the outer rotation axis 15 are perpendicular to each other on the horizontal plane. When the mounting ring 4 is in a horizontal state, the axial directions of the inner rotation axis 14 and the outer rotation axis 15 are the second horizontal direction and the first horizontal direction, respectively. The axes of the inner rotation axis 14 and the outer rotation axis 15 intersect at the center of mass of the atomic gravimeter's falling cavity 5. Two sets of accelerometers 19 are orthogonally distributed, used to detect the horizontal deviation signals of the mounting ring 4 in the first and second horizontal directions, respectively. Two sets of gyroscopes 20 are orthogonally distributed, used to detect the angular rates of the mounting ring 4 in the first and second horizontal directions, respectively. The accelerometers 19 and angular velocity gyroscopes 20 that detect the horizontal deviation signal (angular acceleration) and angular rate of the mounting ring 4 in the first horizontal direction form one group, and the accelerometers 19 and angular velocity gyroscopes 20 that detect the horizontal deviation signal (angular acceleration) and angular rate of the mounting ring 4 in the second horizontal direction form another group. Then, the inner frame torque motor 6 and the outer frame torque motor 8 are controlled separately. The control methods for the inner frame torque motor 6 and the outer frame torque motor 8 are the same, only the parameters are slightly different.

[0069] Step 1: By using the gyroscope 20 to detect the angular rate of the mounting ring 4 in the first horizontal direction and the second horizontal direction, the first angular rate signal and the second angular rate signal of the mounting ring 4 in the first horizontal direction and the second horizontal direction are obtained. The first angular rate signal and the second angular rate signal are converted into electrical signals and transmitted to the digital control circuit after gain amplification.

[0070] The accelerometer, which detects the horizontal deviation signals of the mounting ring 4 in the first and second horizontal directions, is sensitive to and detects the first and second horizontal deviation signals of the mounting ring 4 in the first and second horizontal directions caused by factors such as Earth's rotation, gyroscope drift, and frame initial angle error. After gain amplification, the signals are transmitted to the digital control circuit.

[0071] The first rotation angle signal is obtained by monitoring the rotation angle of the inner frame torque motor 6 relative to the inner frame 3 using the inner frame corner sensor 7, and the second rotation angle signal is obtained by monitoring the rotation angle of the outer frame torque motor 8 relative to the outer frame 2 using the outer frame corner sensor 9. These first and second rotation angle signals are then amplified and transmitted to the digital control circuit. Since the rotation axis of the inner frame torque motor 6 is connected to the inner rotation axis 14, and the rotation axis of the outer frame torque motor 8 is connected to the outer rotation axis 15, the first rotation angle signal output by the inner frame corner sensor 7 is also the rotation angle of the inner rotation axis 14 relative to the inner frame 3, and the second rotation angle signal output by the outer frame corner sensor 9 is also the rotation angle of the outer rotation axis 15 relative to the outer frame 2.

[0072] The first angular rate signal, the first horizontal deviation signal, and the first rotation angle signal are used to adjust the rotation of the rotation shaft of the inner frame torque motor 6.

[0073] The second angular rate signal, the second horizontal deviation signal, and the second rotation angle signal are used to adjust the rotation of the rotating shaft of the outer frame torque motor 8.

[0074] Step 2: If mounting ring 4 is not in a horizontal position, it will be sensitive to both accelerometers. Calculate the first horizontal deviation angular rate of the first horizontal deviation signal and the second horizontal deviation angular rate of the second horizontal deviation signal based on the following formulas;

[0075]

[0076] When formula (5) is used to calculate the first horizontal deviation angular rate: θ is the horizontal deviation of the support frame 1 in the first horizontal direction, and (θ+x" / g) is the first horizontal deviation signal obtained in step 1;

[0077] When formula (5) is used to calculate the second horizontal deviation angular rate: θ is the horizontal deviation of the support frame 1 in the second horizontal direction, and (θ+x" / g) is the second horizontal deviation signal obtained in step 1;

[0078] ω2 is the natural frequency of the second-order pendulum. l2 is the distance from the inner rotation axis 14 to the center of mass of the falling cavity 5 of the atomic gravimeter, θ' is the first derivative of θ, g is the gravitational acceleration, x" is the horizontal acceleration, ζ is the damping coefficient, and g is the gravitational acceleration.

[0079] The calculation process can be seen from formula (5). The horizontal deviation signal measured by accelerometer 19 is multiplied by the constant 2ζω2, and the horizontal deviation signal measured by accelerometer 19 is integrated. The integration constant is ω2. 2 Then, the constant term and the integral term are added together. The constant term is used to dampen the horizontal deviation of the frame, and the integral term is used to determine the natural frequency of the second-stage pendulum.

[0080] The first rotation angle signal and the second rotation angle signal are differentiated to obtain the first rotation angular rate and the second rotation angular rate.

[0081] Step 3: Based on the first angular rate signal, the first horizontal deviation angular rate, and the first rotational angular rate, the digital control circuit calculates the first optimal control signal using the H∞ control algorithm according to the following formulas (6) and (7).

[0082] The digital control circuit calculates the second optimal control signal based on the second angular rate signal, the second horizontal deviation angular rate, and the second rotation angular rate using the H∞ control algorithm according to the following formulas (6) and (7).

[0083] Then, the calculated first and second optimal control signals are amplified by the corresponding power amplifiers and sent to the corresponding pulse code modulation modules to be converted into corresponding pulse code modulation sequences (PMW) and fed back to the inner frame torque motor 6 and the outer frame torque motor 8 respectively. The inner frame torque motor 6 and the outer frame torque motor 8 rotate at a certain rate and response time according to the first and second optimal control signals respectively. The amplitude of the first and second optimal control signals controls the rate, and the lag time of the first and second optimal control signals controls the response time, thereby compensating for the attitude change and acceleration influence of the mounting ring 4, and realizing the attitude stability control and acceleration suppression attenuation of the mounting ring 4.

[0084] To accurately track the optimal control signal, the control bandwidth of the inner frame torque motor 6 and the outer frame torque motor 8 needs to be as large as possible. However, increasing the control system bandwidth also correspondingly reduces the ability to suppress horizontal acceleration. These two indicators are contradictory. Therefore, the choice of bandwidth needs to be made between response speed and the ability to suppress horizontal acceleration. To obtain reasonable control accuracy and natural vibration period, this invention adopts the H∞ control algorithm, the specific steps of which are as follows:

[0085] Based on the hybrid sensitivity H∞ control theory, the H∞ paradigm is as follows:

[0086]

[0087] The expressions for functions S(s), T(s), and R(s) are as follows:

[0088]

[0089] When calculating the first optimal control signal, in formula (6): S(s) is a function that processes the first horizontal deviation angular rate, T(s) is a function that processes the first angular rate signal, and R(s) is a function that processes the first rotational angular rate. In formula (7): A is the function after the Laplace transform of the first horizontal deviation angular rate, B is the function after the Laplace transform of the first angular rate signal, C is the function after the Laplace transform of the first rotational angular rate, and K... W K is the output gain coefficient of the gyroscope 20 that measures the first angular velocity signal. T K is the torque coefficient of the inner frame torque motor 6. R It is the output gain coefficient of the inner frame corner sensor 7;

[0090] When calculating the second optimal control signal, in formula (6): S(s) is a function that processes the second horizontal deviation angular rate, T(s) is a function that processes the second angular rate signal, and R(s) is a function that processes the second rotational angular rate. In formula (7): A is the function after the Laplace transform of the second horizontal deviation angular rate, B is the function after the Laplace transform of the second angular rate signal, C is the function after the Laplace transform of the second rotational angular rate, and K... W K is the output gain coefficient of the gyroscope 20 that measures the second angular rate signal. T K is the torque coefficient of the outer frame torque motor 8. R It is the output gain coefficient of the inner frame corner sensor 7;

[0091] In formula (6): s is a Laplace operator symbol. In control theory, s is generally used to represent the complex frequency domain of the function, s = iω, where ω is the natural frequency of the second-order pendulum, iω represents the complex frequency, and the performance boundary function W S (s) is the weight function of the function S(s); the object uncertainty bound function W T (s) is the weight function of function T(s); the boundary function W R (s) is the weight function of the function R(s). Appropriately select the performance bound function W. S (s) and the object uncertainty bound function W T (s), so that formula (5) holds, so that functions S(s) and T(s) change according to the desired pattern, ensuring that the system has strong stability, good tracking ability and anti-interference ability. A reasonable weight function W is selected. R (s) Avoid saturation of control output.

[0092] In formula (7): I is a unit symmetric matrix, and W(s) is an optimal controller to be determined. Through this optimal controller, an optimal control signal can be obtained, which, after power amplification, drives the corresponding inner frame torque motor 6 or outer frame torque motor 8 in the form of pulse code (PMW).

[0093] According to equations (6) and (7), the optimal controller W(s) corresponding to the inner frame torque motor 6 and the outer frame torque motor 8 can be obtained. Substituting the optimal controller W(s) corresponding to the inner frame torque motor 6 and the outer frame torque motor 8 back into equation (7), S(s), T(s), and R(s) are updated to obtain the updated S(s), T(s), and R(s) corresponding to the inner frame torque motor 6 and the updated S(s), T(s), and R(s) corresponding to the outer frame torque motor 8. The updated S(s), T(s), and R(s) corresponding to the inner frame torque motor 6 are superimposed to obtain the first optimal control signal for controlling the inner frame torque motor 6, and the updated S(s), T(s), and R(s) corresponding to the outer frame torque motor 8 are superimposed to obtain the second optimal control signal for controlling the outer frame torque motor 8.

[0094] Therefore, the gyroscope 20, accelerometer 19, inner frame angle sensor 7, digital control circuit, power amplifier, inner frame torque motor 6 / outer frame torque motor 8 form a control loop, and the closed-loop transfer function Φ(s) of the control loop can be expressed as:

[0095]

[0096] Let s = iω, and combining with equation (4), the horizontal deviation θ caused by the closed-loop transfer function Φ(s) of the control loop through the horizontal acceleration x" can be expressed as:

[0097]

[0098] In formula (9), ω2 is the natural frequency of the second-order pendulum (the natural period is T2 = 2π / ω2), and ω is the natural frequency of the second-order pendulum. It can be seen from formula (9) that a reasonable natural frequency ω2 can be obtained through the optimal controller W(s) and the closed-loop transfer function Φ(s). After obtaining the function S(s) in the previous steps, the bandwidth ω of the function S(s) can be obtained from the function S(s). b The natural frequency of the second-order pendulum is updated based on the following formula: ω b = -3dBω2, which updates the natural frequency of the second-stage pendulum in step 2. According to control theory, the damping coefficient ζ is generally taken as a critical value. The natural frequency ω of the second-order pendulum is further updated to suppress the decaying horizontal acceleration x”, while keeping the horizontal deviation θ within a small range.

[0099] Through this invention, the stabilizing platform can attenuate the horizontal acceleration x" and maintain attitude stability (small horizontal deviation θ), thereby improving the accuracy of dynamic atomic gravity measurement.

[0100] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to replace them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A dynamic measurement stabilization method for atomic gravity, utilizing a dynamic measurement stabilization platform for atomic gravity, including a support frame (1), an outer frame (2) inside the support frame (1), an inner frame (3) inside the outer frame (2), and a mounting ring (4) inside the inner frame (3). The mounting ring (4) is fitted and fixed onto the falling cavity (5) of the atomic gravimeter. Two inner rotating shafts (14) are fixed on the mounting ring (4). The two inner rotating shafts (14) are located on the rotation axis of the mounting ring (4). The two inner rotating shafts (14) are movably mounted on the inner frame (3). One of the inner rotating shafts (14) is connected to the rotation shaft of the inner frame torque motor (6). The fixed part of the inner frame torque motor (6) is mounted on the inner frame (3). An inner frame angle sensor (7) is provided on the inner frame (3) to monitor the rotation angle of the rotation shaft of the inner frame torque motor (6) relative to the inner frame (3). Two external rotating shafts (15) are fixed on the inner frame (3). The two external rotating shafts (15) are located on the rotation axis of the inner frame (3). The two external rotating shafts (15) are movably set on the outer frame (2). One of the external rotating shafts (15) is connected to the rotating shaft of the outer frame torque motor (8). The fixed part of the outer frame torque motor (8) is set on the outer frame (2). An outer frame angle sensor (9) is set on the outer frame (2) to monitor the rotation angle of the rotating shaft of the outer frame torque motor (8) relative to the outer frame (2). The bottom of the outer frame (2) is connected to the top of the buffer support, the bottom of which is located at the bottom of the support frame (1). The top of the outer frame (2) is connected to the top of the support frame (1) via a suspension rope (10). The mounting ring (4) is equipped with two orthogonal accelerometers and two orthogonal fiber optic gyroscopes. The inner frame (3), outer frame (2), atomic gravimeter falling cavity (5), and suspension rope (10) form a first-order pendulum; the atomic gravimeter falling cavity (5), inner frame (3), and outer frame (2) form a second-order pendulum. The first-order pendulum and the second-order pendulum together form a second-order pendulum. When the mounting ring (4) is in a horizontal state, the central axis of the atomic gravimeter falling cavity (5) is in a vertical state. The axis of the inner rotation axis (14) and the axis of the outer rotation axis (15) are perpendicular to each other on the horizontal plane. The axial direction of the inner rotation axis (14) and the axial direction of the outer rotation axis (15) are the second horizontal direction and the first horizontal direction, respectively. The axis of the inner rotation axis (14) and the axis of the outer rotation axis (15) intersect at the center of mass of the atomic gravimeter falling cavity (5); two accelerometers (19) are used to detect the horizontal deviation signal of the mounting ring (4) in the first horizontal direction and the second horizontal direction, respectively. Two gyroscopes (20) are used to detect the angular rate of the mounting ring (4) in the first horizontal direction and the second horizontal direction, respectively. Its features are, The above method includes the following steps: Step 1: Using the gyroscope (20), obtain the first angular velocity signal and the second angular velocity signal of the mounting ring (4) in the first horizontal direction and the second horizontal direction, convert the first angular velocity signal and the second angular velocity signal into electrical signals, and transmit them to the digital control circuit after gain amplification. The first horizontal deviation signal and the second horizontal deviation signal of the mounting ring (4) in the first horizontal direction and the second horizontal direction are obtained by the accelerometer (19), and are transmitted to the digital control circuit after being amplified by the gain. The first rotation angle signal is obtained by the inner frame corner sensor (7), and the second rotation angle signal is obtained by the outer frame corner sensor (9). Then, the first rotation angle signal and the second rotation angle signal are amplified and transmitted to the digital control circuit. Step 2: Calculate the first horizontal deviation angular rate of the first horizontal deviation signal corresponding to the first angular rate signal and the second angular rate signal, and differentiate the first rotation angle signal and the second rotation angle signal to obtain the first rotation angular rate and the second rotation angular rate. Step 3: Based on the first angular rate signal, the first horizontal deviation angular rate, and the first rotational angular rate, calculate the first optimal control signal using the H∞ control algorithm. Based on the second angular rate signal, the second horizontal deviation angular rate, and the second rotational angular rate, the second optimal control signal is calculated using the H∞ control algorithm. The first optimal control signal and the second optimal control signal are then amplified by the corresponding power amplifiers and sent to the corresponding pulse code modulation modules to be converted into corresponding pulse code modulation sequences and fed back to the inner frame torque motor (6) and the outer frame torque motor (8) respectively. The inner frame torque motor (6) and the outer frame torque motor (8) rotate at a certain rate and response time according to the first optimal control signal and the second optimal control signal respectively.

2. The method for stabilizing dynamic measurement of atomic gravity according to claim 1, characterized in that, The first horizontal deviation angular rate of the first horizontal deviation signal in step 2 is calculated based on the following formula: In the above formula: when calculating the first horizontal deviation angular rate: θ is the horizontal deviation of the support frame (1) in the first horizontal direction, and (θ + x" / g) is the first horizontal deviation signal obtained in step 1; When calculating the second horizontal deviation angular rate: θ is the horizontal deviation of the support frame (1) in the second horizontal direction, and (θ + x" / g) is the second horizontal deviation signal obtained in step 1; ω2 is the natural frequency of the second-order pendulum. l2 is the distance from the inner rotation axis (14) to the center of mass of the falling cavity (5) of the atomic gravimeter, θ' is the first derivative of θ, g is the gravitational acceleration, x" is the horizontal acceleration, ζ is the damping coefficient, and g is the gravitational acceleration.

3. The method for stabilizing dynamic measurement of atomic gravity according to claim 2, characterized in that, The H∞ control algorithm in step 3 is based on the following formula: When calculating the first optimal control signal, S(s) is a function processing the first horizontal deviation angular rate, T(s) is a function processing the first angular rate signal, R(s) is a function processing the first rotational angular rate, A is the Laplace transform function of the first horizontal deviation angular rate, B is the Laplace transform function of the first angular rate signal, C is the Laplace transform function of the first rotational angular rate, and K... W K is the output gain coefficient of the gyroscope (20) that measures the first angular velocity signal. T K is the torque coefficient of the inner frame torque motor (6). R It is the output gain coefficient of the inner frame corner sensor (7); When calculating the second optimal control signal, S(s) is a function processing the second horizontal deviation angular rate, T(s) is a function processing the second angular rate signal, R(s) is a function processing the second rotational angular rate, A is the Laplace transform function of the second horizontal deviation angular rate, B is the Laplace transform function of the second angular rate signal, C is the Laplace transform function of the second rotational angular rate, and K... W K is the output gain coefficient of the gyroscope (20) that measures the second angular rate signal. T K is the torque coefficient of the outer frame torque motor (8). R It is the output gain coefficient of the inner frame corner sensor (7); s is the Laplace operator notation, and W is the performance bound function. S (s) is the weight function of the function S(s); the object uncertainty bound function W T (s) is the weight function of function T(s); the boundary function W R (s) is the weight function of the function R(s). I is a unit symmetric matrix. Calculate the optimal controller W(s) corresponding to the inner frame torque motor (6) and the outer frame torque motor (8) that satisfy the above H∞ control algorithm formula. Based on the optimal controller W(s) corresponding to the inner frame torque motor (6) and the outer frame torque motor (8), the functions S(s), T(s), and R(s) are recalculated respectively, and the functions S(s), T(s), and R(s) are superimposed to obtain the first optimal control signal for controlling the inner frame torque motor (6) and the second optimal control signal for controlling the outer frame torque motor (8).

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