阅读说明：本技术 基于速度反馈原理的摆式加速度计闭环控制系统及方法 (Pendulum accelerometer closed-loop control system and method based on speed feedback principle ) 是由 张博文 孙斌 张习文 魏渊 梁璞 李鹏飞 杨夏颖 朱普辉 于 2021-08-20 设计创作，主要内容包括：本发明属于加速度计闭环控制技术领域,具体涉及基于速度反馈原理的摆式加速度计闭环控制系统及方法。该系统包括：速度检测单元,位移检测单元,信号拾取及解调单元,力反馈执行单元。其中,速度检测单元与位移检测单元连接信号拾取及解调单元,信号拾取及解调单元连接力反馈执行单元,实现加速度计系统的闭环控制。该控制方法,同时检测并利用加速度计摆组件的位移信号及速度信号参与控制算法,以实现挠性摆式加速度计在高动态情况下的高速测量。(The invention belongs to the technical field of accelerometer closed-loop control, and particularly relates to a pendulum type accelerometer closed-loop control system and method based on a speed feedback principle. The system comprises: the device comprises a speed detection unit, a displacement detection unit, a signal pickup and demodulation unit and a force feedback execution unit. The speed detection unit and the displacement detection unit are connected with the signal pickup and demodulation unit, and the signal pickup and demodulation unit is connected with the force feedback execution unit to realize the closed-loop control of the accelerometer system. According to the control method, the displacement signal and the speed signal of the accelerometer pendulum component are detected and utilized to participate in a control algorithm, so that high-speed measurement of the flexible pendulum accelerometer under a high dynamic condition is realized.)

1. A pendulum accelerometer closed-loop control system based on velocity feedback principles, comprising: the device comprises a speed detection unit (1), a displacement detection unit (2), a signal pickup and control unit (3) and a force feedback execution unit (4); the signal pickup and control unit (3) is respectively and electrically connected with the speed detection unit (1), the displacement detection unit (2) and the force feedback execution unit (4);

the speed detection unit (1) is used for detecting the movement speed of the pendulum assembly, the displacement detection unit (2) is used for detecting the displacement change of the pendulum assembly, and the force feedback execution unit (4) is used for pulling the pendulum assembly back to a balance position after the pendulum assembly swings; the signal pickup and control unit (3) is used for receiving a speed signal representing the movement speed and a displacement signal representing the displacement change, which are input by the speed detection unit (1), and determining the magnitude of the feedback force according to the two signals; and the driving signal with the feedback force is transmitted to the force feedback execution unit (4), and the force feedback execution unit (4) converts the driving signal into the torsional force for driving the pendulum assembly to move after receiving the driving signal.

2. The system according to claim 1, characterized in that the speed detection unit (1) comprises a speed detection coil (11), a magnetic steel and magnetic field loop (12), a signal demodulator (13);

the speed detection coil (11) is arranged below the moving end of the pendulum assembly (5); the speed detection coil (11) is positioned in the magnetic field of the force speed detection unit (1); the magnetic steel of the speed detection unit (1) and the displacement detection unit (2) are fixed on a base (6) of the system; the signal demodulator (13) is arranged between the speed detection coil (11) and the signal pickup and control unit (3);

when the speed detection coil (11) moves relative to the magnetic steel, a potential difference signal which is in direct proportion to the speed is formed at two ends of the speed detection coil (11) according to the electromagnetic induction principle; the signal demodulator (13) is used for demodulating and amplifying the potential difference signal induced by the speed detection coil (11) into a speed signal.

3. A system according to claim 2, characterized in that the velocity detection coil (11) is wound from a number of turns of an electrically conducting wire with an insulating sheath.

4. The system of claim 1, wherein the displacement sensor selected by the displacement detecting unit comprises a capacitive, photoelectric, or grating displacement sensor.

5. A pendulum accelerometer closed-loop control method based on a speed feedback principle is characterized by comprising the following steps:

picking up a speed signal from a speed detection unit (1) and a displacement signal from a displacement detection unit (2);

comprehensively processing the speed signal and the displacement signal to obtain a feedback signal; the feedback signal can directly influence the damping coefficient of the accelerometer core, namely the response speed of the control system can be adjusted to exceed the bandwidth required by the system, a no-difference system can be formed, and the control precision is improved;

feedback signals are fed back to the input torquer coil (16).

6. The method of claim 5, wherein the transfer function of the synthesis process is:

wherein: u shape_OOutput for the control system; i is_inA displacement signal detected and demodulated by the displacement detection unit; alpha is the offset angle of the pendulum assembly, namely a speed signal; k₁，K₂，K₃Is the proportionality coefficient of each control item; s is the differential sign of the signal and 1/s is the integral sign of the signal.

7. The method of claim 6, wherein after feeding back the feedback signal to the input torquer coil (16), the method further comprises:

the feedback signal is converted into a torsional force for driving the pendulum assembly to move, and the pendulum assembly is pushed to return to a balance position, so that a force balance state is achieved.

8. The method of claim 7, wherein the force feedback actuator is implemented in a form selected from the group consisting of an electromagnetic type and an electrostatic type.

Technical Field

The invention belongs to the technical field of accelerometer closed-loop control, and particularly relates to a pendulum type accelerometer closed-loop control system and method based on a speed feedback principle.

Background

An accelerometer serves as one of core components in an inertial navigation system and provides acceleration information for the system, and the precision of the accelerometer directly influences the precision of the navigation system. At present, high-precision accelerometers at home and abroad basically adopt a closed-loop control mode, namely, a feedback control signal is provided in the accelerometer by detecting the offset condition of a pendulum assembly, a driver is controlled after calculation and demodulation, and the pendulum assembly is pulled back to a balance position, so that the measurement of high-precision acceleration is realized. The closed-loop control accelerometer has obvious advantages in static accuracy, anti-interference capability and the like compared with an open-loop accelerometer because the pendulum assembly can be bound near a fixed position.

A traditional accelerometer closed-loop control system generally comprises a displacement detection device, a demodulation amplification device and a driving device. The displacement detection device can only detect the distance of the pendulum assembly deviating from the balance position, namely displacement detection, but a controlled object is an acceleration value, the displacement is obtained by twice integration of the acceleration, the phase angle value in the amplitude-frequency characteristic lags behind an acceleration signal by 180 degrees, and a signal output by the demodulation and amplification device always lags behind the change of external acceleration, so that the accelerometer has the defects of poor dynamic tracking performance, obvious resonance and large vibration error. Chinese patent CN201710613390.3 discloses an accelerometer control method. The method detects the input signal of the accelerometer, and judges the signal type, the external vibration condition and the like through a computer, thereby giving the compensation amount. The method has the defects that the method depends on complicated sampling and data processing devices and algorithms, the complexity is high, accurate compensation quantity cannot be given under complicated vibration conditions, and the application field of the method is greatly limited. Theoretically, the acceleration amount is controlled by detecting the displacement amount, so that a hysteresis effect always exists, and even if a more complicated control system is designed, the existing problems can be improved a little and cannot be solved fundamentally.

Disclosure of Invention

In view of the above problems of the prior art, it is an object of the present invention to provide a pendulum accelerometer closed-loop control system based on the velocity feedback principle.

A pendulum accelerometer closed-loop control system based on velocity feedback principles, comprising: the device comprises a speed detection unit, a displacement detection unit, a signal pickup and control unit and a force feedback execution unit; the signal pickup and control unit is respectively and electrically connected with the speed detection unit, the displacement detection unit and the force feedback execution unit;

the force feedback execution unit is used for pulling the pendulum assembly back to a balance position after the pendulum assembly swings; the signal pickup and control unit is used for receiving a speed signal representing the movement speed and a displacement signal representing the displacement change, which are input by the speed detection unit, and determining the magnitude of the feedback force according to the two signals; and the force feedback execution unit receives the driving signal and converts the driving signal into a torsional force for driving the pendulum assembly to move.

Furthermore, the speed detection unit comprises a speed detection coil, magnetic steel, a magnetic field loop and a signal demodulator;

the speed detection coil is arranged below the moving end of the pendulum assembly; the speed detection coil is positioned in the magnetic field of the force speed detection unit; the magnetic steel and the displacement detection unit of the speed detection unit are fixed on a base of the system; the signal demodulator is arranged between the speed detection coil and the signal pickup and control unit;

when the speed detection coil moves relative to the magnetic steel, a potential difference signal which is in direct proportion to the speed is formed at two ends of the speed detection coil according to the electromagnetic induction principle; the signal demodulator is used for demodulating and amplifying the potential difference signal induced by the speed detection coil into a speed signal.

Furthermore, the speed detection coil is formed by winding a plurality of turns of conductive cables with insulating sheaths.

Further, the displacement sensor selected by the displacement detection unit comprises a capacitive displacement sensor, a photoelectric displacement sensor and a grating displacement sensor.

A pendulum accelerometer closed-loop control method based on a speed feedback principle comprises the following steps:

picking up a speed signal from the speed detecting unit and a displacement signal from the displacement detecting unit;

comprehensively processing the speed signal and the displacement signal to obtain a feedback signal; the feedback signal can directly influence the damping coefficient of the accelerometer core, namely the response speed of the control system can be adjusted to exceed the bandwidth required by the system, a no-difference system can be formed, and the control precision is improved;

and feeding back the feedback signal to the input torquer coil.

Further, the transfer function of the integration process is:

wherein: u shape_OOutput for the control system; i is_inA displacement signal detected and demodulated by the displacement detection unit; alpha is the offset angle of the pendulum assembly, namely a speed signal; k₁，K₂，K₃Is the proportionality coefficient of each control item; s is the differential sign of the signal and 1/s is the integral sign of the signal.

Further, after feeding back the feedback signal to the input torquer coil, the method further comprises:

the feedback signal is converted into a torsional force for driving the pendulum assembly to move, and the pendulum assembly is pushed to return to a balance position, so that a force balance state is achieved.

Further, the specific implementation form of the force feedback execution unit includes an electromagnetic type and an electrostatic type.

The invention can complete the accelerometer closed-loop control function based on velocity signal feedback. Compared with the traditional single closed-loop feedback control method based on the displacement signal, the control hysteresis of the new method is obviously reduced, the motion trend of the pendulum component can be effectively predicted, the dynamic control precision is improved, and the tracking performance and the reproducibility of the accelerometer to the high dynamic signal are improved. Meanwhile, due to the reason of the optimization of the follow-up performance of the pendulum assembly, the swing amplitude of the pendulum assembly can be effectively reduced, the problem of vibration errors caused by nonlinear factors can be reduced on one hand, on the other hand, the performance of vibration and impact resistance of the accelerometer is improved, and the reliability is improved.

Drawings

FIG. 1 is a diagram of one implementation of a velocity detection unit, a displacement detection unit, a force feedback actuator unit, and a pendulum assembly in a closed-loop control system of the present invention;

FIG. 2 is a block diagram of the overall logic in the closed loop control system of the present invention;

FIG. 3a is a graph of the effect of control based on displacement feedback;

fig. 3b is a graph of the effect of the control based on velocity feedback.

Detailed Description

The technical solution is described in detail below with reference to the accompanying drawings, in conjunction with specific embodiments:

the invention provides a pendulum accelerometer closed-loop control system based on a velocity feedback principle, as shown in figure 1, comprising:

and a speed detection unit 1 for detecting a speed signal of the pendulum assembly. The speed detection unit comprises a speed detection coil, magnetic steel, a magnetic field loop and a signal demodulator. The magnetic steel is fixed on a base of the accelerometer and can generate a uniform magnetic field in a certain area; the speed detection coil is formed by winding a conductive cable with an insulating sheath, one end of the speed detection coil is fixed on the pendulum component and can move along with the pendulum component, and a lead at the other end of the speed detection coil is placed in a magnetic field vertical to the plane of the coil. When the pendulum assembly moves relative to the magnetic steel fixed on the base, the speed induction coil is driven to move, and by the electromagnetic induction principle, potential difference signals U related to the movement speed are generated at two ends of the coil, and voltage signals in direct proportion to the speed can be generated through detection and demodulation of the signal demodulator, so that the function of detecting the speed of the pendulum assembly is achieved.

And the displacement detection unit 2 is used for detecting the displacement condition of the accelerometer pendulum assembly relative to the balance position. The electric signal proportional to the displacement of the pendulum assembly can be output, and the purpose of measuring the displacement of the pendulum assembly is achieved. The specific implementation mode can be various forms such as capacitance type, photoelectric type and grating type.

And a signal pick-up and control unit 3 for picking up the speed signal generated by the speed detection unit and the displacement signal generated by the displacement detection unit. After the signal pickup and demodulation unit obtains the speed signal and the displacement signal, the information of the speed signal and the displacement signal is integrated to form a force feedback current signal which is provided to an accelerometer force feedback mechanism and used for controlling the position of an accelerometer pendulum component so as to detect the external acceleration;

the specific control system design method comprises the following steps:

the picked speed signal is fed back and input to the torquer coil after being amplified proportionally. The speed signal is used for adjusting the damping coefficient of the accelerometer core and improving the corresponding speed of the system.

Secondly, the picked displacement signal is fed back and input into the torquer coil after being amplified in proportion. The displacement signal is used to adjust the eigenfrequency of the accelerometer core.

Integrating and amplifying the displacement signal, and feeding back the displacement signal to the torquer coil. The displacement integral signal is mainly used for forming a no-difference system and improving the control precision.

And fourthly, before the signals are fed back into the coil of the torquer, comprehensive processing, generally addition and reverse processing, is required.

The specific control system design method comprises the following steps:

the picked-up speed signal is fed back to the torquer coil 16 after being amplified proportionally. The feedback of the speed signal can directly influence the damping coefficient of the accelerometer core, namely the response speed of the control system. According to an empirical method, the damping coefficient adjustment principle is that the damping coefficient of the pendulum assembly is matched with the eigen frequency to form a slightly under-damped system, which is generally designed according to the proportion of 1.2, namely, the characteristic root of the system is positioned at omega_n±1.2ω_nWhere ω is_nThe bandwidth frequency required by the system.

Secondly, the picked displacement signal is fed back and input into the torquer coil 16 after being amplified in proportion. The displacement signal is used to adjust the eigenfrequency of the accelerometer core. The eigenfrequency of the core must be adjusted to exceed the required bandwidth of the system.

Integrating and amplifying the displacement signal, and feeding back the displacement signal to the torquer coil 16. The displacement integral signal is mainly used for forming a no-difference system and improving the control precision.

The above signals need to be processed synthetically, typically additively and inversely, before being fed back into the torquer coil 16. The resulting transfer function can be expressed as:

wherein, U_OOutput for the control system; i is_inA displacement signal detected and demodulated by the displacement detection unit; α is the offset angle of the pendulum assembly; k₁，K₂，K₃The proportional coefficients of the control items need to be adjusted according to requirements; s the sign of the differential or integral of the signal.

The above method can be implemented by using an operational amplifier, a differential amplifier, an adder, etc. in a circuit, or by using a computer, a chip with a programming function, etc.

And the force feedback execution unit 4 receives the driving signal of the signal pickup and demodulation unit and converts the force feedback current signal into a torsional force for driving the pendulum assembly to move, so that the pendulum assembly is pushed to return to a balance position to achieve a force balance state. The force feedback actuator can be implemented in various forms such as electromagnetic type and electrostatic type.

The pendulum assembly 5 is composed of a pendulum assembly with one end fixed. When the external has acceleration, the other end moves or swings around the fixed end, so that the acceleration signal is changed into a motion signal.

The pendulum assembly 5 is connected to the speed detecting unit 1 and the displacement detecting unit 2, and the generated motion signal can be detected by both. And then all connected with the signal pick-up and control unit 3, and the force feedback execution unit 4 after generating the final control signal.

First, an accelerometer structure was constructed as shown in fig. 1. In the figure, two pieces of magnetic steel with opposite NS poles can generate uniform magnetic field in the region between the two pieces of magnetic steel. The speed induction coil is connected with the pendulum assembly, and the other end of the speed induction coil is placed in the uniform magnetic field. When the external acceleration influences, the pendulum assembly is acted by the inertial force to swing relative to the rotating shaft, and the pendulum assembly generates speed and displacement. The velocity sensing coil induces an electromotive force in the magnetic field, which accumulates at the two ends of the coil, creating a potential difference. The potential difference is in direct proportion to the swinging speed of the coil, and the direction is related to the swinging direction of the swinging component and the winding mode of the coil. The potential difference is conditioned by the differential amplifying circuit and can be converted into a voltage signal proportional to the swing speed of the pendulum component. The displacement sensor shown in fig. 1 may adopt various forms such as a capacitive type, a photoelectric type, and the like, to realize displacement detection, and output a voltage signal proportional to displacement.

Subsequently, according to fig. 2, the speed and displacement signals detected by the speed detecting unit and the displacement detecting unit are connected to the signal pickup and control unit. The unit can operate and synthesize the two signals. In practical use, parameter design is required according to the transmission characteristics of the controlled object, namely the acceleration measuring unit. Generally, integrators, proportional amplifiers, adders and combinations thereof need to be built to realize the control algorithm.

The signal pickup and control unit outputs a control signal to the force feedback execution unit. The torquer coil in the force feedback unit is placed in the torquer magnetic steel, when current flows through the torquer coil, force perpendicular to the coil can be generated, inertia force on the pendulum component is counteracted, the pendulum component is pulled back to a balance position, and force balance is achieved. At this time, the inertial force applied to the pendulum assembly is equal to the electromagnetic force in the coil.

And connecting the previously built unit structures according to the figure 2 to form a closed-loop feedback control structure. When the pendulum assembly realizes force balance, the external acceleration information can be obtained by detecting the current in the coil, so that the measurement of the acceleration is realized.

The invention provides a method for detecting the swing speed of a swing type accelerometer swing assembly, and a speed signal is introduced into a closed-loop control system to form a novel control mode. According to the control system, the speed signal is introduced, so that the hysteresis of the detection signal is greatly reduced, and the feedback sensitivity of the closed-loop control system is improved. The dynamic tracking characteristic of the accelerometer adopting the control method is obviously improved, and the vibration error is obviously reduced. As shown in fig. 3a and 3b, comparing the control effects based on the displacement feedback and the speed feedback, it can be seen that the resonance peak based on the speed feedback control can be controlled to about 1dB, while the control based on the displacement feedback generally exceeds 5dB, which indicates that the tracking characteristic of the signal is significantly improved and the dynamic performance is greatly improved.