A flexible pendulum angular accelerometer and navigation system

Abstract

The present invention relates to the field of angular accelerometers, and more specifically, to a flexible pendulum angular accelerometer and navigation system. The angular accelerometer comprises a meter and a servo circuit module, which operate according to Newton's laws of mechanics, forming a complete closed-loop feedback loop. The angular accelerometer directly measures the carrier's angular acceleration signal by sensing the inertial force acting on the carrier. The present invention proposes a silicon-based flexible pendulum angular accelerometer that is capable of directly measuring the carrier's angular acceleration signal, featuring high precision, a large measurement range, good real-time performance, a compact size, high reliability, and low cost.

Description

Technical Field

[0001] The present invention relates to the field of angular accelerometers, and in particular to a flexible pendulum angular accelerometer and a navigation system. Background Art

[0002] An angular accelerometer is an inertial meter that directly measures the angular acceleration of a carrier. Compared with the measurement of angular displacement and angular velocity, angular acceleration can characterize the higher-order characteristics of angular motion more directly, quickly, and accurately in terms of dynamic characteristics characterization. Especially under complex working conditions such as multiple disturbances, variable loads, and large overloads, angular acceleration can be directly measured and analyzed with high precision, high dynamics, and high reliability.

[0003] Angular accelerometers have broad application prospects in various industries and fields. Navigation systems incorporating angular accelerometers are ideally suited for aircraft control systems operating at large attitude angles and in large maneuvers. For future highly maneuverable unmanned combat aircraft, flight control systems will require more immediate and accurate angular acceleration information, making angular acceleration sensors particularly important. In missile attitude control systems based on overload control, when a missile simultaneously rotates around two axes at large attitude angles, conventional gyroscopes easily enter a dead zone and fail to accurately reflect the carrier's motion. Consequently, these systems are unable to meet the operational requirements of tactical missiles operating at full attitudes and in large maneuvers. Overload control systems based on angular accelerometers can effectively achieve large-sector missile launches. In satellite attitude control systems, angular accelerometers directly measure torque in servo turntable control systems, effectively reducing high-frequency noise interference caused by the gyroscope's angular velocity differential, enabling more accurate torque compensation and control, and improving system stability. Angular accelerometers can also be used in fields such as human motion and joint dynamics analysis, virtual reality, oil exploration, and earthquake monitoring.

[0004] Currently, angular acceleration signals are typically obtained by differentiating the output signal of an angular rate gyroscope. However, this differential processing is subject to large errors, interference, and a certain degree of delay. Alternatively, several linear accelerometers can be used for measurement, followed by complex information processing to obtain the angular acceleration signal, but this approach is complex and costly. Chinese patent CN1156677C discloses a liquid ring angular accelerometer that can directly measure and obtain angular acceleration signals. However, its large size and mass, low accuracy, small range, and high production cost make it suitable only for limited, specific scenarios. Summary of the Invention

[0005] The purpose of the present invention is to provide a flexible pendulum angular accelerometer based on silicon material which has high precision, large measuring range, good real-time performance, small size, high reliability and low cost and can directly measure the angular acceleration signal of the carrier.

[0006] Technical solution:

[0007] A flexible pendulum angular accelerometer, characterized by comprising: a meter head and a servo circuit module; these operate according to Newton's laws of mechanics, forming a complete closed-loop feedback loop, and directly measuring the carrier's angular acceleration signal by sensing the inertial force exerted on the carrier of the flexible pendulum angular accelerometer;

[0008] Among them, the meter head is used to sense the inertial force exerted on the carrier; generate an induced current and transmit the induced current to the servo circuit module; the servo circuit module is used to process the induced current and convert the induced current into a voltage used to characterize the angular acceleration of the carrier.

[0009] The meter head includes: a magnet, a lower capacitor plate, a detection mass assembly, an upper transfer plate, and a housing; the lower capacitor plate, the detection mass assembly, and the upper transfer plate are placed on the magnet in order from bottom to top;

[0010] Among them, the detection mass assembly is the core component of the angular accelerometer, which includes a torquer coil, a first pad, a pendulum, and a second pad that are fixed in sequence;

[0011] The magnet is used to stably provide a uniform magnetic field; the shell has magnetic permeability, and the magnet is fixed to the bottom surface of the shell; the lower capacitor plate is a chassis with insulating and thermal conductive functions, and two centrally symmetrical gold-plated areas are provided on the upper surface of the chassis; the pendulum includes a stator, a rotor and a flexible beam; the rotor is fixed to the stator through the flexible beam, and the rotor can rotate and swing around the flexible beam under the action of inertia; the two gold-plated areas constitute the fixed area of ​​the differential capacitor; the rotor constitutes the dynamic area of ​​the differential capacitor; the rotor and the lower capacitor plate together constitute a differential capacitor meter; the torquer coil and the magnet constitute a permanent magnet torquer; the upper transfer plate is also a chassis with insulating and thermal conductive functions, and there is a conductive strip plated with gold film on the chassis for transferring the electrical signals of the differential capacitor meter and the permanent magnet torquer.

[0012] The preferred material for the pendulum is single crystal silicon.

[0013] The first spacer and the second spacer are preferably made of a high-density alloy material.

[0014] The thickness of the flexible beam is on the order of microns. When an angular acceleration signal is input, the detection mass assembly will rotate and swing around the flexible beam.

[0015] Magnets are made of permanent magnetic materials.

[0016] The preferred material for the chassis is ceramic.

[0017] The torquer coil is wound with copper wire.

[0018] Beneficial effects of the present invention: The present invention proposes a flexible pendulum angular accelerometer with the characteristics of high precision, large range, good real-time performance, small size, high reliability and low cost. The main parameters are shown in Table 1. It has obvious advantages over the current domestic related products, can realize high-precision, high-dynamic and high-reliability direct measurement and analysis of angular acceleration, and has broad application prospects.

[0019] Table 1. Main parameters of angular accelerometer

[0020] name parameter size ≤26mm×26mm×26mm weight ≤60g Measurement accuracy ≤0.1° / s2 Range <h2 style=";text-align:left;direction:ltr"><![CDATA[≥1×10 <h2 style=";text-align:left;direction:ltr"> 6 <h2 style=";text-align:left;direction:ltr"> ° / s2]]><h2 style=";text-align:left;direction:ltr"> Startup time ≤1s BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the overall appearance of the present invention;

[0022] Figure 2 This is a schematic diagram of the structure of the header of the present invention;

[0023] Figure 3 is a schematic diagram of a proof mass assembly of the present invention;

[0024] Figure 4 It is a working principle diagram of the present invention;

[0025] Figure 5 The curve of the change rule of the angular accelerometer output over time is measured by using the angular accelerometer provided by the present invention according to the above test method.

[0026] Among them, 1-header, 2-servo circuit module, 3-magnet, 4-lower capacitor plate, 5-detection mass component, 6-torquer coil, 7-first pad, 8-single crystal silicon pendulum, 8-1-fixed plate, 8-2-moving plate, 9-flexible beam, 10-second pad, 11-upper adapter plate, 12-shell. DETAILED DESCRIPTION

[0027] The present invention is further described in detail below in conjunction with the accompanying drawings and specific implementations. Those skilled in the art should understand that the description is exemplary, and the present invention is not limited to the specific implementation methods. Those skilled in the art can make various combinations, modifications and changes to the present invention. Those skilled in the art should understand that as long as they do not depart from the purpose and spirit of the present invention, various combinations, modifications and changes made to the present invention should fall within the scope of the present invention, and the scope of protection of the present invention is given by the appended claims.

[0028] The present invention provides a flexible pendulum angular accelerometer, comprising: a meter head and a servo circuit module, wherein the servo circuit module is placed on the meter head; the servo circuit module operates according to Newton's laws of mechanics, forming a complete closed-loop feedback loop, and directly measures the angular acceleration signal of the carrier by sensing the inertial force exerted on the carrier of the flexible pendulum angular accelerometer;

[0029] The meter is used to sense the inertial force acting on the carrier, generate an induced current, and transmit the induced current to the servo circuit module. The servo circuit module processes the induced current, converting it into a voltage signal representing the angular acceleration of the carrier. This current signal is then fed back to the torquer to generate a balancing torque. The angular acceleration value is thus detected by detecting the current passing through the torquer.

[0030] Furthermore, the meter head includes: a magnet, a lower capacitor plate, a detection mass assembly, an upper transfer plate, and a housing;

[0031] Among them, the detection mass component is the core component of the angular accelerometer, which includes a torquer coil, a first pad, a pendulum, and a second pad fixed in sequence; the torquer coil, the first pad, the second pad and the outer moving plate part of the pendulum constitute the pendulum mass, which passes through two flexible beams arranged on the pendulum and two bosses arranged on the upper and lower surfaces of the stator inside the pendulum, and is fixedly connected between the lower capacitor plate and the upper adapter plate to sense the angular acceleration vector of the carrier.

[0032] The shell is a cavity structure with a magnetic conductivity function; a central column is provided in the shell, and a magnet, a lower capacitor plate, a detection mass component, and an upper transfer plate are placed in sequence from bottom to top; a through hole is provided in the middle of the magnet to cooperate with the central column of the shell, and the magnet is fixed to the bottom surface of the shell by adhesive bonding to stably provide a uniform magnetic field; the lower capacitor plate is composed of a chassis with an insulating and heat-conducting function, and two gold-plated films arranged symmetrically on the upper surface of the chassis, and three through holes are provided on the lower capacitor plate, the middle through hole is used to cooperate with the central column of the shell, and the through holes on both sides are used for routing, and the two gold-plated films constitute the fixed area of ​​the differential capacitor; the torquer coil is a circular coil, and the torquer coil is arranged under the pendulum through a first pad; the torquer coil and the magnet constitute a permanent magnet torquer; the pendulum includes a stator, a moving plate and Two flexible beams; the stator is a special-shaped plate structure with a through hole in the middle, and the movable plate is a special-shaped plate structure arranged on the periphery of the stator. The movable plate is fixedly connected to the stator through the flexible beam, and the movable plate can rotate and swing around the flexible beam under the action of inertia force; the movable plate of the differential capacitor constitutes the dynamic area of ​​the differential capacitor; the movable plate and the lower capacitor plate together constitute a differential capacitor meter; the stator is provided with an upper boss and a lower boss, the upper boss is used to press-fit with the upper transfer plate, and the lower boss is used to press-fit with the lower capacitor plate; the upper transfer plate is also composed of a chassis with insulating and heat-conducting functions, and a gold-film-plated conductive tape on the chassis. Five through holes are provided on the upper transfer plate, among which the middle through hole is used to cooperate with the central column of the shell, and the remaining two square through holes and two circular through holes are used for routing. The gold-film-plated conductive tape is used to transfer the electrical signals of the differential capacitor meter and the permanent magnet torquer.

[0033] Furthermore, the preferred material for the pendulum piece, the core component of quality detection, is single crystal silicon. The pendulum piece is a single crystal silicon integral pendulum made through MEMS silicon micromachining technology. The single crystal silicon material has small elastic hysteresis, small thermal expansion coefficient, good thermal conductivity, and large elastic modulus, which is conducive to achieving low temperature coefficient, good temperature uniformity and high structural stability. At the same time, due to the semiconductor properties of silicon material, it can form one pole of the capacitor without the need for gold film plating process.

[0034] Furthermore, the preferred material of the first pad and the second pad is a tungsten-based high-density alloy material, and the density of the tungsten-based high-density alloy material is as high as 17.2g / cm 3 , which can provide higher quality in a smaller volume.

[0035] Furthermore, the flexible beam can be processed using wet etching technology to achieve a thickness of 10 microns, while maintaining a tolerance of plus or minus 1 micron. When an angular acceleration signal is input, the detection mass component will rotate and swing around the flexible beam. A sufficiently thin flexible beam can significantly increase the sensitivity of the detection mass component's swing.

[0036] Furthermore, the shell is made of a soft magnetic alloy material, which has high magnetic permeability and low coercive force, and can shield the external magnetic field.

[0037] Furthermore, the magnetic steel is made of permanent magnetic material, which can provide a uniform magnetic field for the torquer. When current flows through the torquer coil, permanent magnetic torque can be generated.

[0038] Furthermore, the torquer coil is wound with a copper wire having a diameter of 0.04 mm and 200 turns.

[0039] Furthermore, the preferred material for the chassis of the lower capacitor plate and the chassis of the upper adapter plate is ceramic material. Ceramic material has insulation and heat conduction functions, and the thermal expansion coefficient of ceramic material is similar to that of single crystal silicon material, and will not introduce large environmental stress in a variable temperature environment.

[0040] The flexible pendulum angular accelerometer according to the present invention is characterized in that the detection mass component is the core component of the sensitive angular acceleration signal, and the two flexible beams constitute the rotation axis O axis of the detection mass component. Figure 3 As shown, the proof mass assembly has a large moment of inertia J about the rotation axis. O The large moment of inertia helps to improve the resolution of the angular accelerometer. When there is an angular acceleration input, the detection mass component swings to generate a torsional inertia moment. The flexible beam undergoes torsional elastic deformation under the action of the torsional inertia moment, thereby causing the movable plate of the pendulum to produce an angular displacement around the rotation axis.

[0041] The detection mass component needs to be designed and precisely assembled so that its center of mass is located at the center of the rotation axis. In this way, the detection mass component can be insensitive to linear acceleration. At the same time, the detection mass component passes through the center of mass and the moment of inertia J of the I axis perpendicular to the pendulum surface I and the moment of inertia J about the P axis which is perpendicular to both the O axis and the I axis and passes through the center of mass P Equal, I axis and P axis as Figure 3 As shown, the unequal inertia error of the detection mass component is minimized as much as possible; in addition, the inertia product J of the detection mass component around any two of the three axes must be OI 、J OP 、J IP As close to zero as possible, the inertial product error of the proof mass assembly is minimized; this way, the proof mass assembly can be insensitive to angular acceleration about non-rotating axes. By achieving the above points, the proof mass assembly can achieve accurate detection of angular acceleration.

[0042] The flexible pendulum angular accelerometer according to the present invention is characterized in that the rotor of the pendulum and the lower capacitor plate form a differential capacitor. When the rotor of the pendulum rotates and swings, the distance between the two gold film areas on the lower capacitor plate and the pendulum becomes unequal, causing the capacitance on both sides to also become unequal, resulting in a capacitance difference. The capacitance differential measurement method has high displacement detection resolution. The method of integrating the lower capacitor plate with the single-crystal silicon pendulum to form a differential capacitor has a simple structure, a small size, and is easy to implement in terms of process, and can be sensitive to minute angular acceleration changes.

[0043] The flexible pendulum angular accelerometer according to the present invention is characterized by the torquer coil and the magnet forming a permanent magnet torquer. When the differential capacitance changes, an induced current is output through the servo circuit module. When this current passes through the torquer coil, the magnetic field provided by the magnet generates a balancing torque to offset the inertial force generated by the external inertial angular acceleration, thereby achieving force balance in the closed-loop system. The magnitude of the feedback current supplied to the torquer coil is proportional to the value of the input inertial angular acceleration, thereby achieving angular acceleration measurement. The permanent magnet force feedback method has a simple structure, enables closed-loop control, has few factors affecting stability, and easily achieves high scale factor stability.

[0044] Optionally, the housing and the servo circuit module may be sealed by laser welding to improve the stability of the internal structure of the angular accelerometer and enable the angular accelerometer to maintain stable operation in harsh environments such as variable pressure, humidity and heat.

[0045] Optionally, a thermistor element may be added to the servo circuit module to detect the temperature; a digital processing circuit or a digital output circuit may also be connected to the servo circuit module to convert the current / voltage signal into a digital signal for processing.

[0046] Optionally, a gas of a certain pressure, such as helium, may be encapsulated inside the meter head to further improve the stability inside the angular accelerometer. At the same time, by adjusting the air damping inside the angular accelerometer, the air film damping effect is enhanced, thereby improving the dynamic performance of the angular accelerometer.

[0047] The technical solution of the present invention is as follows: the angular accelerometer uses the detection mass of the precision elastic element to sense the angular acceleration signal and convert it into angular displacement, and then detects the angular displacement through the capacitance differential measurement method, generating a current proportional to the capacitance difference. The current is processed by the servo circuit module and loaded on the torque coil. The current-carrying torque coil generates an electromagnetic torque opposite to the torque brought by the angular acceleration under the action of the magnetic field, so that the detection mass component returns to the equilibrium position. At the same time, an outward output current proportional to the input angular acceleration is obtained, thereby realizing the measurement of angular acceleration. The angular accelerometer is composed of a servo circuit and a meter head, wherein the meter head includes a detection mass component, a magnet made of permanent magnetic material, a lower capacitor plate with a gold film, an upper transfer plate and a shell. The detection mass component includes a single crystal silicon pendulum and a mass block and a torquer coil bonded to the pendulum. The detection mass component is supported by two flexible beams.

[0048] It should be noted that the proof mass assembly of the angular accelerometer involved in the present invention is the core of the sensitive angular acceleration signal. Its characteristics are: ideally, the proof mass assembly is only sensitive to the angular acceleration of the moving carrier. When there is an angular acceleration input, the proof mass assembly rotates around the rotation axis connected by the two flexible beams, and the generated inertia moment is expressed as follows:

[0049]

[0050] Among them, J O To detect the moment of inertia of the mass component around the rotation axis O, is the angular acceleration of the moving carrier around the rotation axis O.

[0051] However, in actual situations, when the carrier has various motions in other directions, the detection mass component will also undergo a certain degree of rotational swing, resulting in dynamic errors. Through the analysis of rigid body dynamics theory, it can be known that the dynamic error expression of the angular accelerometer is as follows:

[0052]

[0053] Where m is the mass of the detection mass assembly, l is the distance that the center of mass of the detection mass assembly deviates from the rotation axis O (we call ml the pendulum), and a I is the linear acceleration of the vertical pendulum. P To detect the moment of inertia of the mass component around the P axis, J Iis the moment of inertia of the mass component around the I axis, J IO J is the inertia product of the detection mass component around the O axis and the I axis. OP is the inertia product of the detection mass component around the OA axis and the PA axis, J PI is the product of inertia of the detection mass assembly around the P axis and the I axis, ω O is the angular velocity of the detection mass assembly around the O axis, ω I is the angular velocity of the detection mass assembly around the I axis, ω P To detect the angular velocity of the mass component around the P axis, To detect the angular acceleration of the mass component around the I axis, is the angular acceleration of the detection mass component around the P axis, θ O is the steady-state output angle of the proof-mass assembly.

[0054] There are four main errors:

[0055] (1) The first term on the right is the linear acceleration error term, which is caused by the deviation of the center of mass of the detection mass component. It is necessary to make its center of mass located at the center of the rotation axis through structural design and precise assembly;

[0056] (2) The second term on the right is the unequal inertia error term, which requires structural design to make the moment of inertia J of the detection mass component around the non-sensitive axis P and J I Equal to reduce;

[0057] (3) The third, fourth, and fifth items on the right are the inertia product error items, which need to be designed structurally to make the inertia product J IO 、J PI 、J OP are all close to 0 to reduce;

[0058] (4) The fourth term is the unequal inertia coupling error term, which can be reduced by increasing the balance loop gain.

[0059] The working principle of the angular accelerometer proposed in the present invention is: when there is an angular acceleration signal input, the detection mass component is sensitive to the angular acceleration and rotates and swings around the flexible beam to generate angular displacement; a capacitance detector is formed between the coating area on the lower capacitor plate and the single crystal silicon pendulum. When there is no angular acceleration signal input, the detection mass component is in a balanced position, and the capacitance formed between the coating area on both sides of the fixed plate and the single crystal silicon pendulum is equal, and no differential current is generated. When the detection mass component is sensitive to the angular acceleration signal and rotates and swings, a capacitance detector is formed between the coating area on both sides of the lower capacitor plate and the pendulum. One side of the capacitance becomes larger and the other side becomes smaller, and the difference generates an induced current; a permanent magnetic feedback torquer assembly is formed between the coil of the detection mass assembly and the magnet made of permanent magnetic material. When the detection mass assembly deflects, an induced current is generated. After the current passes through the coil, it is affected by the magnetic field to generate feedback force, which pulls the detection mass assembly back to the equilibrium position; the servo circuit module converts and amplifies the current signal and outputs a voltage signal. After obtaining the voltage signal, the angular acceleration signal can be obtained through a certain algorithm; the shell and the servo circuit module are fully sealed by laser welding.

[0060] like Figure 1 As shown, the angular accelerometer of the present invention comprises a meter head 1 and a servo circuit module 2, which together form a complete closed-loop feedback system. This system operates according to Newtonian mechanics, directly measuring the carrier's angular acceleration signal by measuring the inertial force acting on the carrier. Laser welding seals the system together, ensuring the stability of the meter head's internal structure. As can be seen from the figure, the present invention has a very simple appearance.

[0061] The meter head is the main working part of the angular accelerometer. Its structural diagram is as follows: Figure 2As shown, it includes a magnet 3, a lower capacitor plate 4, a detection mass component 5, an upper transfer plate 11, and a shell 12. The magnet 3 is made of permanent magnetic material and can stably provide a uniform magnetic field. The shell 12 is made of soft magnetic alloy material and has good magnetic permeability. The magnet 3 and the shell 12 are bonded together by glue. The lower capacitor plate 4 is made of a disc made of ceramic material. The ceramic material has good thermal conductivity to facilitate timely heat dissipation of the angular accelerometer during operation. There are two gold-plated areas on the ceramic disc, and these two areas constitute the fixed area of ​​the differential capacitor. The detection mass component 5 is the core component of the angular accelerometer involved in the present invention, which can directly sense the angular acceleration signal. It consists of a torquer coil 6, a first pad 7, a single crystal silicon pendulum 8, and a second pad 10. Among them, the single crystal silicon pendulum piece 8 constitutes the dynamic area of ​​the differential capacitor due to the semiconductor properties of its material, and it and the above-mentioned lower capacitor plate 4 together form a differential capacitance meter; the torquer coil 6, the first pad 7 and the second pad 10 and the dynamic plate 8-1 of the single crystal silicon pendulum piece together constitute the pendulum mass (i.e., the detection mass component), which are bonded together with glue, wherein the first pad 7 and the second pad 10 are made of high-density alloy material, which has a very high density and can provide sufficient weight in a small volume. The pendulum mass is connected to the fixed plate of the single crystal silicon pendulum piece 8 through a flexible beam 9. The thickness of the flexible beam 9 is in the micron range. When an angular acceleration signal is input, the pendulum mass will rotate and swing around the flexible beam 9; the torquer coil 6 is made of copper wire, and it and the magnet 3 constitute a permanent magnet torquer; the upper transfer plate 10 is also made of a ceramic material with a disc base, and the disc has a gold film-plated conductive strip for transferring signals. A platform is provided on the stator 8-1, which serves as a support for the upper transfer plate 11. There is a gap between the upper transfer plate 11 and the second pad 10. In the structure of the present invention, some parts need to be hollowed out to facilitate wiring, such as Figure 2 The holes on the middle and lower capacitor plates 4 and the notches on the circumference of the rotor are used for wiring.

[0062] Combine Figure 3The working principle of the angular accelerometer involved in the present invention is that when the angular accelerometer is in a stationary state, the distance between the moving piece 8-2 of the single crystal silicon pendulum and the two gold-plated areas of the lower capacitor plate 4 is equal, and the differential capacitor is zero. When an angular acceleration signal is input, the detection mass component 5 is sensitive to the angular acceleration and swings around the flexible beam 9. At this time, the distance between the two ends of the single crystal silicon pendulum 8 and the two gold-plated areas of the lower capacitor plate 4 is no longer equal, resulting in a capacitance difference. The differential capacitor is sensitive to the capacitance difference and generates a current proportional to the capacitance difference. The current is filtered, integrated, amplified, and processed by the servo circuit module 2 and then loaded on the torque coil 6. The current-carrying torque coil generates an electromagnetic torque in the opposite direction to the torque brought by the angular acceleration under the action of the magnetic field generated by the magnet 3, so that the detection mass component 5 generates an angular acceleration with the same direction and equal magnitude as the input angular acceleration, so that the detection mass component 5 returns to the equilibrium position (the differential capacitance is 0). At this time, by utilizing the force feedback principle, a current proportional to the input angular acceleration is obtained on the torque coil 6. The current is analyzed and calculated by the servo circuit module 2 to obtain the input angular acceleration signal, thereby realizing the measurement of angular acceleration.

[0063] In the present invention, the servo circuit module 2 can adopt a servo circuit of a conventional structure such as Figure 4 As shown, a traditional structure typically includes a CV readout circuit (including a differential capacitance detector), a proportional-integral-differential (PID) control circuit (including an integrator), a transconductance amplifier circuit (including a transconductance / compensation amplifier), and a feedback torque-enhancing circuit. These circuits primarily implement physical quantity conversion (CV), signal conditioning for the static and dynamic characteristics of the closed-loop system, and voltage-to-current conversion and drive capability. In this circuit, a triangle wave generator serves as the carrier power supply for the differential capacitance detector, modulating the signal. The differential capacitance detection output is an electrical signal proportional to the differential output of the capacitance sensor. The integrator and transconductance / compensation amplifier compensate and correct the signal, improving the static and dynamic quality of the system. The final stage supplies a constant current source to the torquer coil to rebalance the current. These circuits, along with the differential capacitor and proof-mass assembly 5, form a complete force-balanced closed-loop system. Within the feedback torque-enhancing circuit, analog negative feedback—the feedback torque-enhancing method uses analog current—and pulse servo negative feedback—the feedback and torque-enhancing method uses pulsed current. Pulsed current can include modulated pulse widths and intermittent pulses. The servo circuit module 2 is a hybrid integrated circuit. Hybrid integrated circuits are a very mature technology and can be designed directly by referring to existing technologies or directly purchased as a commodity.

[0064] To further illustrate the function of the angular accelerometer of the present invention, the following experiments were conducted:

[0065] 1) The angular accelerometer is installed on the turntable of a precision centrifuge through a special test fixture, and the sensitive axis of the angular accelerometer coincides with the rotation axis of the centrifuge turntable;

[0066] 2) Connect the relevant cables, power on the angular accelerometer, and start continuously collecting the angular accelerometer output voltage signal;

[0067] 3) Keep the centrifuge turntable stationary for 20 seconds;

[0068] 4) Set a certain angular acceleration Control the turntable to start rotating with uniform angular acceleration;

[0069] 5) When the turntable reaches a certain angular velocity ω (the acceleration process takes 20 seconds), it starts to rotate at a uniform angular velocity;

[0070] 6) Set the reverse angular acceleration after 20 seconds The turntable is controlled to start rotating with uniform angular acceleration, and when the angular velocity reaches -ω (40s), it starts rotating at a uniform angular velocity.

[0071] 7) After 20 seconds, control the turntable to angular acceleration Come to a standstill and remain still for 20 seconds.

[0072] Figure 5 This graph shows the temporal variation of the angular accelerometer output, measured using the test method described above, using the angular accelerometer provided by the present invention. As can be seen from the graph, when there is no angular acceleration signal input, the angular accelerometer output remains unchanged, regardless of the presence of an angular acceleration signal. However, when there is an angular acceleration signal input, the angular accelerometer can effectively sense the angular acceleration signal. This demonstrates that the angular accelerometer provided by the present invention can directly and accurately sense angular acceleration signals.

Claims

1. A flexible pendulum angular accelerometer, characterized in that: include: The meter head (1) and the servo circuit module (2) operate according to Newton's law of mechanics to form a complete closed-loop feedback, and directly measure the angular acceleration signal of the carrier by sensing the inertial force exerted on the carrier of the flexible pendulum angular accelerometer; The meter (1) is used to sense the inertial force exerted on the carrier; generate an induced current and transmit the induced current to the servo circuit module (2); the servo circuit module (2) is used to process the induced current and convert the induced current into a voltage for representing the angular acceleration of the carrier; The meter head (1) comprises: a magnetic steel (3), a lower capacitor plate (4), a detection mass component (5), an upper transfer plate (11), and a housing (12); the lower capacitor plate (4), the detection mass component (5), and the upper transfer plate (11) are placed on the magnetic steel (3) in order from bottom to top; The detection mass component (5) is the core component of the angular accelerometer, and the two flexible beams constitute the rotation axis O of the detection mass component; the detection mass component (5) is designed and precisely equipped so that its center of mass is located at the center of the rotation axis; The detection mass assembly (5) comprises a torquer coil (6), a first pad (7), a pendulum piece, and a second pad (10) which are fixedly connected in sequence; The magnetic steel (3) is used to stably provide a uniform magnetic field; the shell (12) has magnetic conductivity, and the magnetic steel (3) is fixed to the inner bottom surface of the shell (12); the lower capacitor plate (4) is a chassis with insulation and heat conduction functions, and the upper surface of the chassis is provided with two centrally symmetrical gold-plated areas; the swing plate includes a fixed plate (8-1), a movable plate (8-2) and a flexible beam (9); the movable plate (8-2) is fixedly connected to the fixed plate (8-1) through the flexible beam (9), and the movable plate (8-2) can rotate and swing around the flexible beam (9) under the action of inertia force; the two gold-plated areas constitute The fixed area of ​​the differential capacitor; the moving plate (8-2) constitutes the moving area of ​​the differential capacitor; the moving plate (8-2) and the lower capacitor plate (4) together constitute the differential capacitance meter; the torquer coil (6), the first pad (7) and the second pad (10) together with the moving plate (8-2) of the single crystal silicon pendulum plate constitute the pendulum mass; the torquer coil (6) and the magnetic steel (3) constitute the permanent magnet torquer; the upper transfer plate is also a chassis with insulating and heat conducting functions, and there is a gold film-plated conductive strip on the chassis for transferring the electrical signals of the differential capacitance meter and the permanent magnet torquer; When there is an angular acceleration input, the detection mass component rotates around the rotation axis connected by the two flexible beams, generating an inertial moment M The expression is as follows: Among them, J O To detect the moment of inertia of the mass component around the rotation axis O, is the angular acceleration of the moving carrier around the rotation axis O; When the carrier has various motions in other directions, the detection mass component will also undergo a certain rotational swing, resulting in dynamic errors. Through the analysis of rigid body dynamics theory, it can be known that the dynamic error of the angular accelerometer is The expression is as follows: Where m is the mass of the detection mass assembly, L is the distance of the center of mass of the detection mass assembly offset from the rotation axis O, mL is the pendulum, and a I is the linear acceleration of the vertical pendulum plane; J P To detect the moment of inertia of the mass component around the P axis, J I is the moment of inertia of the mass component around the I axis, J IO J is the inertia product of the detection mass component around the O axis and the I axis. OP is the inertia product of the detection mass component around the OA axis and the PA axis, J PI To detect the inertia of the mass component around the P axis and the I axis, To detect the angular velocity of the mass component around the O axis, is the angular velocity of the detection mass assembly around the I axis, To detect the angular velocity of the mass component around the P axis, To detect the angular acceleration of the mass component around the I axis, To detect the angular acceleration of the mass component around the P axis, is the steady-state output angle of the proof-mass assembly.

2. The angular accelerometer according to claim 1, wherein: The servo circuit module (2) is placed on the meter head (1); the two work according to Newton's law of mechanics to form a complete closed-loop feedback, and directly measure the angular acceleration signal of the carrier by sensing the inertial force exerted on the carrier of the flexible pendulum angular accelerometer.

3. The angular accelerometer according to claim 1, wherein: The material of the pendulum is single crystal silicon.

4. The angular accelerometer according to claim 1, wherein: The first cushion block (7) and the second cushion block (10) are made of a high-density alloy material.

5. The angular accelerometer according to claim 1, wherein: The thickness of the flexible beam (9) is on the order of micrometers. When an angular acceleration signal is input, the detection mass component (5) rotates and swings around the flexible beam (9).

6. The angular accelerometer according to claim 1, wherein: The magnetic steel (3) is made of permanent magnetic material.

7. The angular accelerometer according to claim 1, wherein: The chassis is made of ceramic.

8. The angular accelerometer according to claim 1, wherein: The torquer coil (6) is wound with copper wire.

9. A navigation system, characterized in that: The angular accelerometer comprises the angular accelerometer according to any one of claims 1 to 8.

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