RU2629654C1 - Linear microaccelerometer - Google Patents

Abstract

FIELD: measuring equipment.

SUBSTANCE: linear microaccelerometer contains a base, a frame with inertial mass fixed on resilient suspensions, a position sensor, a voltage source, four comparators, two current amplifiers, a key, an electromagnetic actuator consisting of 2N coils arranged on 2N magnetically conductive cores, opposite frame sides by N on each side, and on the surface of the inertial mass on each side there are magnetic circuits closing the magnetic fluxes of the coils. The coil inputs are connected to the output of the key, whose inputs through the comparators are connected to the position sensor, which is made optical and consists of a radiator connected to the voltage source and two photodetectors. There are four optical cables between the radiator and the photodetectors, and the inertial mass is made in the form of a pendulum with the possibility of making torsional oscillations on resilient suspensions around one axis and contains two shutters mounted with the possibility to block the light flux between the radiator and the photodetectors arranged on the base.

EFFECT: increasing the accuracy, expanding the range of measured accelerations and reducing nonlinearity.

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Description

The claimed technical solution relates to measuring technique and can be used in orientation and navigation systems.

Known "Pendulum compensation accelerometer" (patent US 6422076 B1, IPC G01P 15/13, publ. 07.23.2002), containing a housing in which the pendulum block is made in the form of a single plate of single-crystal silicon, which contains a movable blade on an elastic suspension and supporting frame with protrusions. On the opposite sides of the movable blade two magnetic systems and two coils of the rotary device are fixed, which are located with a gap relative to the core and are fixed on the corresponding side of the moving blade. The elastic suspension contains flexible elements located at an angle of 90 degrees relative to each other, symmetrically with respect to the axis of symmetry of the pendulum device. When the accelerometer accelerates, the movable blade deviates in the opposite direction to acceleration, and the current in the coils returns the movable blade to its original position. The measured current in the coils is used to determine the acceleration.

A disadvantage of the known analogue is the high non-linearity and, as a consequence, low accuracy.

The well-known "Linear microaccelerometer" (RF patent 2410703, IPC G01P 15/08, publ. 01/27/2011) containing a housing, a cover, two inertial masses on elastic suspensions, made in the form of rectangular plates of single-crystal silicon and located in the same plane in series with each other one after the other along the axis of sensitivity with the possibility of linear movement. Two position sensors for each inertial mass are made in the form of two pairs of emitters and photodetectors. The first of them are located in the openings of the lid above the rectangular plates, and the second ones are coaxially aligned with them in the housing. In this case, each pair of photodetectors is connected to its corresponding comparator. The outputs of the comparators are connected to the keys, to which a stabilized current source is also connected. The outputs of the keys through elastic suspensions are connected to the conductive paths of the compensation transducers, made in the form of two permanent magnets placed on the cover and the housing, and conductive paths sprayed on the surface of rectangular plates perpendicular to the sensitivity axis. The invention improves the accuracy of measurements by introducing a mode of self-oscillations.

A disadvantage of the known analogue is the narrow passband, as well as the need to place the emitter and photodetectors in close proximity to the inertial mass, which leads to low accuracy in measuring acceleration.

The closest known technical solution is the "Linear microaccelerometer" (RF patent 2561303, C1 IPC G01P 15/08, publ. 08/27/2015) containing a base, a cover, a frame with an inertial mass made of silicon, mounted with linear movement on elastic suspensions along the longitudinal axis, a position sensor and a voltage source, characterized in that two comparators, two current amplifiers, a key, an electromagnetic power drive, consisting of 2N coils placed on 2N magnetic conductors are additionally introduced into the device cores with pronounced poles directed to the end sides of the inertial mass, while the magnetically conductive cores are placed on the opposite end sides of the frame with N on each side, and on the surface of the inertial mass in the area of each of the ends are magnetic circuits that close the magnetic fluxes of the coils, and the inputs of the coils connected to the output of the key, the inputs of which through comparators are connected to a position sensor, which is made optical and consists of a radiator and photodetectors, while the radiator By connecting the voltage source and between the emitter and photodetectors is optical gap.

The disadvantage of the prototype is the complex design of the elastic suspensions and their large length, the need to place the emitter and photodetectors in close proximity to the inertial mass, as well as a narrow passband, and as a result, low accuracy of acceleration measurement.

The task is to create a linear microaccelerometer that measures accelerations with higher accuracy.

The technical result that provides a solution to the problem is to increase the accuracy of measuring acceleration.

The technical result is achieved by the fact that in a linear microaccelerometer containing a base, a frame with an inertial mass mounted on elastic suspensions, a position sensor, a voltage source, four comparators, two current amplifiers, a key, an electromagnetic power drive, consisting of 2N coils placed on 2N magnetic conductive cores, which are located on opposite sides of the frame in N on each side, and on the surface of the inertial mass on each side are magnetic circuits that close the magnetic flux of the coils, The coil inputs are connected to the key output, the inputs of which through the comparators are connected to a position sensor, which is optical and consists of an emitter connected to a voltage source and two photodetectors, four optical cables are located between the emitter and photodetectors, and the inertial mass is made in the form of a pendulum with the possibility of torsional vibrations on elastic suspensions around one axis and contains two dampers installed with the possibility of overlapping the light flux between the emitter and photodetector nicknames posted on the basis of.

The technical result is achieved due to the fact that the execution of the inertial mass in the form of a pendulum allows it to perform more stable torsional vibrations on elastic suspensions around one axis under the action of an alternating DC signal generated in the feedback circuit of an electromagnetic power drive controlled by an optical position sensor, and application four optical cables allows you to more accurately record its position. The presence of the input action leads to a shift in the center of oscillation and the appearance of temporary modulation of the signal. Measuring the temporal modulation of the signal can further improve the accuracy of the measurement of acceleration.

The analysis of the prior art by the applicant has established that there are no analogs characterized by sets of features identical to all the features of the claimed angular accelerometer, therefore, the claimed invention meets the “novelty” condition.

Search results for known technical solutions in this and related fields of technology in order to identify features that match the distinctive features of the claimed invention from the prototypes showed that they do not follow explicitly from the prior art.

From the prior art determined by the applicant, the influence of the transformations provided for by the essential features of the claimed invention on the achievement of the indicated technical result has not been revealed, therefore, the claimed invention corresponds to the “inventive step”.

The essence of the technical solution is illustrated by drawings, where in FIG. 1 shows a structural diagram of the device, in FIG. 2 - relay control law, in FIG. 3 - the law of control with delay, in FIG. 4 - the control law is ahead of schedule and the following notation is introduced:

1. The basis

2. Frame

3. Inertial mass

4. Elastic suspensions

5. Damper

6. Damper

7. Emitter

8. Photodetector

9. Photodetector

10. Fiber optic cable

11. Fiber optic cable

12. Fiber optic cable

13. Fiber optic cable

14. Voltage source

15. Comparator

16. Comparator

17. Comparator

18. Comparator

19. Coil

20. Coil

21. Magnetically conductive core

22. Magnetically conductive core

23. Magnetic circuit

24. Magnetic circuit

25. The key

26. Current amplifier

27. Current amplifier.

The proposed linear microaccelerometer consists of a base 1, a frame 2 with an inertial mass 3, mounted on elastic suspensions 4 and containing two shutters 5 and 6. The optical position sensor of the inertial mass 3 is made of emitter 7, photodetectors 8, 9 and fiber optic cables 10, 11, 12, 13, while the emitter 7 is connected to a voltage source 14, and the photodetectors 8 and 9 are connected to the comparators 15, 16, 17 and 18. The electromagnetic power drive consists of 2N coils 19, 20 located on 2N magnetically conductive cores 21, 22 with distinct poles directed to the end sides of the inertial mass 3, while the magnetically conducting cores 21, 22 are located on opposite sides of the inertial mass 3 of N on each side, and the magnetic cores 23, 24 are located on the surface of the inertial mass 3 on each side. Coils 19 and 20 are connected to the output of the key 25 through the current amplifiers 26 and 27, respectively. The inputs of the key 25 are connected to the comparators 15, 16, 17 and 18.

The base 1, the frame 2, the inertial mass 3 and the elastic suspensions 4 are made, for example, of single-crystal or polycrystalline silicon or quartz.

The emitter 7 is made, for example, on the basis of a commercially available laser diode LFO-401 from the FTI-Optronic company [1], designed for a wavelength of 1300 nm or any compatible with the selected type of optical fiber.

Photodetectors 8 and 9 are made, for example, based on commercially available TrueLight TMS-1C31-000 photodiodes [2], designed for a wavelength of 1300 nm, or any compatible with the selected type of optical fiber.

Fiber optic cables 10, 11, 12 and 13 can be single-mode or multimode, for example, with a standard sheath diameter of 125 μm and a standard core diameter of 9, 50 or 62.5 μm.

The voltage source 14 is made, for example, based on a commercially available chip (voltage source) Mitsubishi Electric M5294 [3].

Key 25 is made, for example, based on a commercially available NJM2520V microcircuit [4] or based on microcircuits operating in the asynchronous RS-trigger mode.

Current amplifiers 26, 27 are made, for example, on the basis of a commercially available microcircuit (operational amplifier) Mitsubishi Electric M5216 [5].

Comparators 15, 16, 17 and 18 are made, for example, on the basis of a commercially available microcircuit (comparator) Mitsubishi Electric M51203 [4]. Comparators are selected in such a way as to send a signal to the key 25 in accordance with the selected control law, which can be relay (Fig. 2), with delay (Fig. 3) or ahead of schedule (Fig. 4), for this they can respond to low or high signal level from photodetectors 8 and 9, as well as to the front or cut of this signal.

Fiber optic cables 10, 11, 12, 13 are fixed in the recesses in the frame so that when the inertial mass fluctuates, the dampers alternately overlap the light flux between the emitter 7 and the photodetectors 8 and 9. The shape of the dampers 5 and 6 is selected so that the triggering times of the comparators 15, 16, 17 and 18 due to changes in the luminous flux exactly corresponded to the selected control law, for this, recesses and / or protrusions on the surface of the shutters 5 and 6 are added.

The operation of the device is divided into three stages, depending on the control law.

Work using the relay control law (Fig. 3):

1.1. Exit to the operating mode.

After power-up, the base 1 and the inertial mass 3 in the frame 2 are at rest. Key 25 is in the preset state "1". The voltage from the output of the key 25 begins to flow to the first current amplifier 26. The electric current created by it in the first coil 19 induces a magnetic field in the first magnetically conducting core 21, which, tending to close through the first magnetic circuit 23, attracts the inertial mass 3. As a result, the inertial mass 3 rotates on elastic suspensions 4 in the direction of the first coil 19 until the damper 6 blocks the luminous flux passing through the fiber optic cables 10 and 11 between the emitter 7, powered by a voltage source 14, and by the receiver 9. At the moment when the shutter 6 blocks the luminous flux, the signal from the photodetector 9, converted by the comparators 15, 16, 17 and 18, sets the key 25 to the state “-1”, as a result of which the voltage from the output of the key 25 starts to flow to the second current amplifier 27, the signal from which is supplied to the second coil 20. This turns off the first current amplifier 26, the signal from which ceases to go to the first coil 19. The electric current generated by the second current amplifier 27 in the second coil 20 induces an electric current in the second magnetically conducting core 22 a magnetic field, which, trying to close through the second magnetic circuit 24, attracts the inertial mass 3 to the second coil 20. After completing paragraph 1.1, the first half-cycle of paragraph 1.2 begins.

1.2. The first half period.

The inertial mass 3 by inertia continues to rotate on the elastic suspensions 4 towards the first coil 19 until the elastic force and the force of attraction of the inertial mass 3 to the second coil 20 balances the momentum of the inertial mass 3. After that, the inertial mass 3 under the action of the elastic force movement to the second coil 20 until the shutter 5 blocks the luminous flux passing through the fiber optic cables 12 and 13 between the emitter 7, powered by a voltage source 14, and the photodetector 8. At that moment, when the shutter 5 blocks the light flux, the signal from the photodetector 8, converted by the comparators 15, 16, 17 and 18, sets the key 25 to state “1”, as a result of which the voltage from the output of the key 25 starts to flow to the first current amplifier 26, the signal from which is fed to the first coil 19. In this case, the second current amplifier 27 is turned off, the signal from which ceases to flow to the second coil 20. The electric current created by the first current amplifier 26 in the first coil 19 induces a magnetic field in the first magnetically conducting core 21, which tends to close Without the first magnetic circuit 23, it attracts the inertial mass 3 to the first coil 19. The second half-cycle begins (Sec. 1.3).

1.3. The second half period.

The inertial mass 3 by inertia continues to rotate on the elastic suspensions 4 towards the second coil 20 until the elastic force and the force of attraction of the inertial mass 3 to the first coil 19 balance the momentum of the inertial mass 3. After that, the inertial mass 3 under the action of the elastic force movement to the first coil 19 until the shutter 6 blocks the luminous flux passing through the fiber optic cables 10 and 11 between the emitter 7, powered by a voltage source 14, and the photodetector 9. At the moment when the shutter 6 it closes the luminous flux, the signal from the photodetector 9, converted by the comparators 15, 16, 17 and 18, sets the key 25 to the state “-1”, as a result of which the voltage from the output of the key 25 starts to flow to the second current amplifier 27, the signal from which is fed to the second coil 20. In this case, the first current amplifier 26 is turned off, the signal from which ceases to flow to the first coil 19. The electric current created by the second current amplifier 29 in the first coil 19 induces a magnetic field in the second magnetically conducting core 22, which tends to close of the second magnetic core 24 attracts the inertial mass 3 to the second coil 20. The first half cycle starts (n. 1.2), and the cycle repeats again.

Thus, the inertial mass 3 begins to oscillate at its own frequency according to the relay control law shown in FIG. 3, and the signal from photodetectors 8 and 9 takes the form of a meander with a duty cycle of 50%. Under the influence of external acceleration, a shift of the center of oscillation of the inertial mass 3 occurs. This shift causes a change in the duty cycle of the signal from the photodetectors 8 and 9, which is proportional to the current acceleration.

Work using the control law with delay (Fig. 3) or ahead of schedule (Fig. 4):

2.1. Exit to the operating mode.

After turning on the power, the base 1, frame 2 and inertial mass 3 are at rest. Key 25 is in the preset state "1". The voltage from the output of the key 25 begins to flow to the first current amplifier 26. The electric current created by it in the first coil 19 induces a magnetic field in the first magnetically conducting core 21, which, tending to close through the first magnetic circuit 23, attracts the inertial mass 3. As a result, the inertial mass 3 rotates on elastic suspensions 4 together with shutters 5 and 6 in the direction of the first coil 19 until it passes through point T1a (Fig. 4). At this point, the position of the shutters 5 and 6 causes a change in the light flux passing through the fiber optic cables 10, 11, 12 and 13 between the emitter 7, powered by a voltage source 14, and the photodetectors 8 and 9, as a result of which the comparator 15 is triggered, the signal from which the key 25 is switched to the state “-1”, as a result of which the first current amplifier 26 is turned off, the signal from which ceases to flow to the first coil 19, and the voltage from the output of the key 25 begins to flow to the second current amplifier 27, the signal from which begins to arrive on the second to 20. Starting first carcass half (Sec. 2.2).

2.2. First half period

The electric current created by the second current amplifier 27 in the second coil 20 induces a magnetic field in the second magnetically conducting core 22, which, trying to close through the second magnetic circuit 24, attracts the inertial mass 3 to the second coil 20.

The inertial mass 3 by inertia continues to rotate on the elastic suspensions 4 together with the shutters 5 and 6 in the direction of the first coil 19 until the elastic force and the force of attraction of the inertial mass 3 to the second coil 20 balance the momentum of the inertial mass 3. After that, the inertial mass 3, under the action of the elastic force, begins to move to the second coil 20 until it passes through point T2a (Fig. 4). At this moment, the position of the shutters 5 and 6 causes a change in the light flux passing through the fiber optic cables 10, 11, 12 and 13 between the emitter 7, powered by a voltage source 14, and the photodetectors 8 and 9, as a result of which the comparator 16 is triggered, the signal from which the key 25 is switched to the state “0”, as a result of which the second current amplifier 27 is turned off, the signal from which ceases to flow to the second coil 20.

The inertial mass 3 by inertia continues to rotate on the elastic suspensions 4 together with the shutters 5 and 6 in the direction of the second coil 20 until it passes through the point T1b (Fig. 4). At this moment, the position of the shutters 5 and 6 causes a change in the light flux passing through the fiber optic cables 10, 11, 12 and 13 between the emitter 7, powered by a voltage source 14, and the photodetectors 8 and 9, as a result of which the comparator 17 is triggered, the signal from which the key 25 is switched to state “1”, as a result of which the first current amplifier 26 is turned on, the signal from which begins to flow to the first coil 19. The second half-cycle begins (paragraph 2.3).

2.3. Second half period

The electric current created by the first current amplifier 26 in the first coil 19 induces a magnetic field in the first magnetically conducting core 21, which, trying to close through the first magnetic circuit 23, attracts the inertial mass 3 to the first coil 19.

The inertial mass 3 by inertia continues to rotate on the elastic suspensions 4 together with the shutters 5 and 6 towards the second coil 20 until the elastic force and the force of attraction of the inertial mass 3 to the first coil 19 balance the momentum of the inertial mass 3. After that, the inertial mass 3 under the action of the elastic force begins to move to the first coil 19 until it passes through point T2b (Fig. 4). At this point, the position of the shutters 5 and 6 causes a change in the light flux passing through the fiber optic cables 10, 11, 12 and 13 between the emitter 7, powered by a voltage source 14, and the photodetectors 8 and 9, as a result of which the comparator 18 is triggered, the signal from which the key 25 is switched to the state “0”, as a result of which the first current amplifier 26 is turned off, the signal from which ceases to flow to the first coil 19.

The inertial mass 3 by inertia continues to rotate on the elastic suspensions 4 together with the shutters 5 and 6 in the direction of the first coil 19 until it passes through the point T1a (Fig. 4). At this point, the position of the shutters 5 and 6 causes a change in the light flux passing through the fiber optic cables 10, 11, 12 and 13 between the emitter 7, powered by a voltage source 14, and the photodetectors 8 and 9, as a result of which the comparator 15 is triggered, the signal from which the key 25 is switched to the state “-1”, as a result of which the second current amplifier 27 is turned on, the signal from which begins to flow to the second coil 20. The first half-cycle begins (paragraph 2.2).

Thus, the inertial mass 3 begins to oscillate at the natural frequency according to the delay control law shown in FIG. 3 (or with the lead shown in Fig. 4), and the signal from the photodetectors 8 and 9 takes the form of a meander. Under the influence of external acceleration, a shift of the center of oscillation of the inertial mass 3 occurs. This shift causes a change in the duty cycle of the signal from the photodetectors 8 and 9, which is proportional to the current acceleration.

The construction of an accelerometer using a pendulum circuit allows to reduce the length of the suspensions, which reduces the influence of manufacturing errors and increases reliability, and reduce unwanted effects acting on the inertial mass by increasing the frequency of the second resonance.

In addition, the use of an optical position sensor allows one to reduce the error in determining the switching moment, and the use of an optical cable reduces the manufacturing cost both through the use of standard solutions of fiber-optic communication lines and due to the possibility of placing optical emitters and receivers on the device case without resorting to the laborious process of their manufacture directly on the basis. Additionally, this allows, if necessary, to increase the power of the emitter, for example, to compensate for misalignment due to errors in the manufacture of the base.

The use of an electromagnetic power drive allows you to increase the magnitude of the generated force, which expands the range of measured accelerations, and also allows you to increase the frequency of self-oscillations, which extends the bandwidth of the device.

The use of self-oscillation mode allows you to create a self-regulating system, less sensitive to external noise. In addition, this reduces the availability time of the device and eliminates the use of analog components and a measuring circuit, which increases the accuracy of the measurement, reduces non-linearity and extends the range of measured accelerations.

The application of control laws other than relay allows one to further increase the frequency of self-oscillations and reduce the amplitude, which extends the dynamic range of the device and reduces energy consumption, leading to an increase in accuracy.

Using the advanced device allows to improve the metrological characteristics of inertial modules, namely accuracy, the range of measured accelerations, non-linearity, as well as reduce the cost of production and size in comparison with the use of analogs that provide similar measurement accuracy.

Information sources

1. Technical description of the single-mode laser diode LFO-401 [Electronic resource] / FTI-Optronik. - Electron, text data. - SPb .: 2016. - Access mode: http://www.fti-optronic.com/pdfs/LFO-401.pdf, free.

2. Technical description of GaAs PIN photodiode [Electronic resource] / FTI-Optronik. - Electron, text data. - SPb: 2016. - Access mode: http://www.fti-optronic.com/pdfs/TMC-8D31-000.pdf, free.

3. Library of electronic components. Issue 1: Kingbright Optoelectronic Devices. - M .: DODEKA, 1999 .-- 64 p.

4. Library of electronic components. Issue 17: Analog and Digital-to-Analog Microcircuits by Mitsubishi Electric. - M: DODEKA, 2000 .-- 48 p.

5. Microcircuits for audio and radio equipment. - 2. - M.: Dodeka XXI Publishing House, 2001. - 288 p.

Claims (1)

A linear microaccelerometer containing a base, a frame with an inertial mass mounted on elastic suspensions, a position sensor, a voltage source, four comparators, two current amplifiers, a key, an electromagnetic power drive, consisting of 2N coils placed on 2N magnetically conductive cores that are placed from opposite sides of the frame with N on each side, and on the surface of the inertial mass on each side there are magnetic cores that close the magnetic fluxes of the coils, and the inputs of the coils are connected to the output of the key, which, through comparators, is connected to a position sensor, which is optical and consists of an emitter connected to a voltage source and two photodetectors, characterized in that there are four optical cables between the emitter and photodetectors, and the inertial mass is made in the form of a pendulum with the possibility of making torsional oscillations on elastic suspensions around one axis and contains two dampers installed with the possibility of blocking the light flux between the emitter and photodetectors placed on basis.

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