CN115372654B - Permanent magnet negative stiffness active absolute speed sensor and control method thereof - Google Patents
Permanent magnet negative stiffness active absolute speed sensor and control method thereof Download PDFInfo
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- CN115372654B CN115372654B CN202211002482.5A CN202211002482A CN115372654B CN 115372654 B CN115372654 B CN 115372654B CN 202211002482 A CN202211002482 A CN 202211002482A CN 115372654 B CN115372654 B CN 115372654B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P3/00—Measuring linear or angular speed; Measuring differences of linear or angular speeds
- G01P3/42—Devices characterised by the use of electric or magnetic means
- G01P3/50—Devices characterised by the use of electric or magnetic means for measuring linear speed
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P1/00—Details of instruments
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P1/00—Details of instruments
- G01P1/02—Housings
- G01P1/026—Housings for speed measuring devices, e.g. pulse generator
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P25/00—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details
- H02P25/02—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details characterised by the kind of motor
- H02P25/032—Reciprocating, oscillating or vibrating motors
- H02P25/034—Voice coil motors
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)
Abstract
本发明提供一种永磁负刚度主动绝对速度传感器及其控制方法，属于速度检测领域，绝对速度传感器包括：外壳、执行部件、永磁负刚度部件、弹性部件、轴、参考质量块、相对位移传感器及控制部件。外壳固定在被测对象上；执行部件及永磁负刚度部件设置在外壳的内部；轴从下至上依次穿过执行部件、永磁负刚度部件、外壳的上表面及弹性部件；相对位移传感器测量外壳与轴的相对位移；控制部件根据相对位移产生反馈控制信号，执行部件在反馈控制信号的作用下抑制参考质量块的运动，进而将相对位移信号转化成被测对象的绝对速度信号。降低了绝对速度传感器的固有频率，减少了参考质量块的位移，提高了绝对速度传感器的稳定性及低频性能。
The present invention provides a permanent magnetic negative stiffness active absolute speed sensor and a control method thereof, which belongs to the field of speed detection. The absolute speed sensor comprises: a housing, an actuator, a permanent magnetic negative stiffness component, an elastic component, a shaft, a reference mass block, a relative displacement sensor and a control component. The housing is fixed on the object to be measured; the actuator and the permanent magnetic negative stiffness component are arranged inside the housing; the shaft passes through the actuator, the permanent magnetic negative stiffness component, the upper surface of the housing and the elastic component from bottom to top in sequence; the relative displacement sensor measures the relative displacement between the housing and the shaft; the control component generates a feedback control signal according to the relative displacement, and the actuator suppresses the movement of the reference mass block under the action of the feedback control signal, thereby converting the relative displacement signal into the absolute speed signal of the object to be measured. The natural frequency of the absolute speed sensor is reduced, the displacement of the reference mass block is reduced, and the stability and low-frequency performance of the absolute speed sensor are improved.
Description
Technical Field
The invention relates to the field of speed detection, in particular to a permanent magnet negative stiffness active absolute speed sensor and a control method thereof.
Background
The precise vibration isolation system is the fundamental guarantee of stable operation of ultra-precise manufacturing and measuring equipment. As equipment enters nano/sub-nano precision, the need for high performance vibration isolation is becoming more stringent. Reducing the natural frequency of the vibration isolation system and introducing active vibration control become the main means for improving the vibration isolation performance. Inertial sensors, represented by acceleration, absolute velocity measurements, are key devices to achieve active vibration isolation. However, the application of active control in vibration isolation systems of low natural frequencies places higher demands on the low frequency measurement capabilities of inertial sensors, especially absolute velocity sensors.
The current small commercial absolute speed sensor mainly comprises a shell, a permanent magnet fixedly connected with the shell, an inertial reference mass, a metal spring and other components, wherein the inertial reference mass is coated and sleeved on the permanent magnet through the coil, and the metal spring plays a supporting role between the mass and the shell. When the shell is subjected to external vibration, the shell and the reference mass generate relative motion, and the induced coil cuts magnetic force lines to generate voltage proportional to the absolute speed of the shell within a certain bandwidth. The transfer function of the external speed input to the sensor voltage output of the absolute speed sensor exhibits a high-pass characteristic, the cut-off frequency of which is determined by the internal mechanical spring and the inertial reference mass. By analyzing the structural composition characteristics of the absolute velocity sensor, it can be seen that increasing the reference mass and reducing the stiffness of the metal spring can reduce the low-frequency cutoff frequency of the sensor, so that the low-frequency performance of the sensor is enhanced, but increasing the reference mass can obviously increase the volume of the sensor, and according to the definition of the stiffness, the increase of the bearing capacity or the reduction of the stiffness can lead to the rapid increase of deformation quantity and the corresponding increase of the volume of the sensor, which can lead to the difficulty of sensor design and integration. In addition, the reduction of the stiffness of the metal spring can reduce the stability of the system, reduce the linear displacement interval of the system and lead to nonlinear response of the sensor.
In order to further improve the low-frequency performance of the absolute speed sensor, the defect of a common metal spring is overcome, a permanent magnet is utilized to construct a permanent magnet negative stiffness spring to replace the metal spring to realize the reduction of stiffness, and the idea of expanding the low-frequency performance of the sensor is proposed, however, as the spatial magnetic field strength is strongly related to the nonlinearity of the relative position between the magnets forming the magnetic field, the reference mass borne by the permanent magnet negative stiffness spring and the sensor shell are continuously changed along with the different vibration inputs, the spatial magnetic field is caused to be changed, the negative stiffness magnetic force and the output of an induced coil are caused to be nonlinear, and the measurement performance of the absolute speed sensor is seriously influenced.
In addition, the configuration of the combination of the coil winding and the permanent magnet can generate negative rigidity, reduce the natural frequency of the system and improve the linearity of the rigidity section of the electromagnetic negative rigidity mechanism. However, such a mechanism requires a continuous power supply, and in particular, coil windings require constant current drive to produce stable negative stiffness, and high heat generation of the coil windings is unavoidable. The continuous heating can cause the resistance characteristic change of the coil winding of the self-body, and the electromagnetic force output precision is affected. At the same time, the heating causes the environment around it to warm up, which is detrimental to the low frequency thermal noise control of the inertial sensor. Moreover, when the electromagnetic negative stiffness mechanism and the metal spring have a misalignment installation problem, the initial acting force of the negative stiffness mechanism can cause the reference mass to further drift.
Disclosure of Invention
The invention aims to provide a permanent magnet negative stiffness active absolute speed sensor and a control method thereof, which can improve the stability and low-frequency performance of the absolute speed sensor.
In order to achieve the above object, the present invention provides the following solutions:
a permanent magnet negative stiffness active absolute velocity sensor for measuring an absolute velocity of a measured object, the permanent magnet negative stiffness active absolute velocity sensor comprising:
the lower surface of the shell is fixedly arranged on the tested object;
an execution part arranged inside the shell;
The permanent magnet negative stiffness component is arranged in the shell;
the elastic component is fixedly arranged on the upper surface of the shell;
the shaft sequentially passes through the execution part, the permanent magnet negative stiffness part, the upper surface of the shell and the elastic part from bottom to top, and the bottom of the shaft is suspended in the shell;
a reference mass fixedly disposed on top of the shaft;
The relative displacement sensor is fixedly arranged on the upper surface of the shell and is used for measuring the relative displacement between the reference mass block and the upper surface of the shell to obtain a relative displacement signal;
The control component is connected with the relative displacement sensor and the execution component and is used for generating a feedback control signal according to the relative displacement signal;
the execution component is used for inhibiting the relative movement of the reference mass block and the shell under the action of the feedback control signal, and the relative displacement signal is used for determining the absolute speed of the measured object after feedback control.
Optionally, the executing component comprises a magnet and a coil;
the magnet is suspended in the shell, fixed with the shaft and provided with a groove at the lower part;
the coil is arranged in the groove of the magnet, fixedly connected with the bottom of the shell and connected with the control part;
the feedback control signal is used to control the magnitude of the current applied to the coil.
Optionally, the actuator is a voice coil motor.
Optionally, the permanent magnet negative stiffness component comprises a first permanent magnet ring, a second permanent magnet ring, a third permanent magnet ring and a fourth permanent magnet ring;
The axes of the first permanent magnetic ring, the second permanent magnetic ring, the third permanent magnetic ring and the fourth permanent magnetic ring are the same, and the shaft penetrates through the axes of the first permanent magnetic ring, the second permanent magnetic ring, the third permanent magnetic ring and the fourth permanent magnetic ring;
The inner diameter and the outer diameter of the first permanent magnetic ring are equal to the inner diameter and the outer diameter of the second permanent magnetic ring, the inner diameter of the third permanent magnetic ring is larger than the outer diameter of the first permanent magnetic ring, and the inner diameter of the third permanent magnetic ring is equal to the outer diameter of the fourth permanent magnetic ring;
The first permanent magnet ring and the second permanent magnet ring are fixed on the shaft, and the lower surface of the first permanent magnet ring is fixedly connected with the upper surface of the second permanent magnet ring;
The third permanent magnet ring and the fourth permanent magnet ring are fixedly connected with the shell, and an axial gap is set between the third permanent magnet ring and the fourth permanent magnet ring.
Optionally, the axial heights of the first permanent magnet ring, the second permanent magnet ring, the third permanent magnet ring and the fourth permanent magnet ring are equal.
Optionally, the elastic component is a metal spring.
Optionally, the permanent magnet negative stiffness active absolute velocity sensor further comprises an air bearing guide rail;
the air bearing guide rail is fixed in the shell, the shaft penetrates through the air bearing guide rail, and the air bearing guide rail is used for restraining the movement direction of the shaft.
Optionally, the permanent magnet negative stiffness active absolute speed sensor further comprises an axial adjusting nut;
The axial adjusting nut is arranged between the reference mass block and the elastic component, the shaft penetrates through the axial adjusting nut, and the axial adjusting nut is used for adjusting the initial position of the shaft.
In order to achieve the above purpose, the present invention also provides the following solutions:
A control method of a permanent magnet negative stiffness active absolute speed sensor comprises the following steps:
Fixing the lower surface of the shell on a measured object;
when the measured object moves, the reference mass block is displaced under the action of the shaft, and the relative displacement between the reference mass block and the upper surface of the shell is acquired through the relative displacement sensor, so that a relative displacement signal is obtained;
And generating a feedback control signal according to the relative displacement signal, controlling an execution part to restrain the relative motion of the reference mass block and the shell, and determining the absolute speed of the measured object after the relative displacement signal is subjected to feedback control.
Optionally, the executing component is a voice coil motor;
the control execution part suppresses the relative motion of the reference mass block and the shell, and specifically comprises:
converting the relative displacement signal into a voltage signal according to the gain of the relative displacement sensor and the turning angle frequency of the relative displacement sensor;
According to the voltage signal, a differential controller, a low-frequency stabilizing filter, a differential intensity adjusting filter and a high-frequency dynamic suppression filter are adopted to determine a control voltage signal;
the method comprises the steps of determining a feedback control signal according to a thrust constant of a voice coil motor, a gain of a driving circuit, turning angle frequency of the driving circuit and the control voltage signal, wherein the feedback control signal is used for controlling the current applied to the voice coil motor, the voice coil motor inhibits relative movement of the reference mass block and the shell under the action of the feedback control signal, and the absolute speed of a measured object is determined after the relative displacement signal is subjected to feedback control.
According to the specific embodiment provided by the invention, the lower surface of the shell is fixed on a measured object, the execution part and the permanent magnet negative stiffness part are arranged in the shell, the shaft sequentially passes through the execution part, the permanent magnet negative stiffness part, the upper surface of the shell and the elastic part from bottom to top, the bottom of the shaft is suspended in the shell, the reference mass block is arranged at the top of the shaft, the relative displacement between the reference mass block and the upper surface of the shell is measured through the relative displacement sensor, and the absolute speed of the measured object is determined after feedback control. The design of the permanent magnet negative stiffness component reduces the natural frequency of the absolute speed sensor and avoids the problem of constant current heating of the electromagnetic negative stiffness. The control part generates a feedback control signal to perform feedback control on the execution part, so that the displacement of the reference mass block is reduced, the problem of magnetic nonlinearity is restrained, and the stability and low-frequency performance of the absolute velocity sensor are improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the drawings that are needed in the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a front view of a permanent magnet negative stiffness active absolute velocity sensor of the present invention;
FIG. 2 is a schematic cross-sectional view of a permanent magnet negative stiffness active absolute velocity sensor of the present invention;
FIG. 3 is a schematic view of the direction of magnetization of a permanent magnet ring in a permanent magnet negative stiffness component;
FIG. 4 is a schematic diagram of a control framework of a permanent magnet negative stiffness active absolute velocity sensor;
FIG. 5 is a schematic diagram of a feedback control strategy;
FIG. 6 is a frequency response diagram of a feedback control strategy;
FIG. 7 is a flow chart of a control method of the permanent magnet negative stiffness active absolute velocity sensor.
Symbol description:
The device comprises a relative displacement sensor-1, a reference mass block-2, a linear displacement guide rail-3, a shaft-4, an axial adjusting nut-5, a metal spring-6, a first air bearing guide rail-7, a second air bearing guide rail-8, a permanent magnet negative stiffness component-9, a voice coil motor-10, a shell-11, a first permanent magnet ring-12, a second permanent magnet ring-13, a third permanent magnet ring-14, a fourth permanent magnet ring-15, a magnet-16, a coil-17 and a measured object-18.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The invention aims to provide a permanent magnet negative stiffness active absolute speed sensor and a control method thereof, wherein the natural frequency of the absolute speed sensor is reduced through a permanent magnet negative stiffness component, and the problem of constant current heating of electromagnetic negative stiffness is avoided. The control part generates a feedback control signal to perform feedback control on the execution part, so that the displacement of the reference mass block is reduced, the problem of magnetic nonlinearity is restrained, and the stability and low-frequency performance of the absolute velocity sensor are improved.
In order that the above-recited objects, features and advantages of the present invention will become more readily apparent, a more particular description of the invention will be rendered by reference to the appended drawings and appended detailed description.
As shown in fig. 1 and 2, the permanent magnet negative stiffness active absolute velocity sensor of the present invention comprises a housing 11, an executing component, a permanent magnet negative stiffness component 9, an elastic component, a shaft 4, a reference mass 2, a relative displacement sensor 1 and a control component.
Wherein the lower surface of the housing 11 is fixedly disposed on the object 18 to be measured. In the present embodiment, the housing 11 is fixed to the object 18 to be measured through the screw hole, so that the movement states of the object 18 to be measured and the housing 11 are completely identical. The object 18 is free to move and the invention measures the velocity value of the object 18 in the direction of the sensor axis 4.
The actuator and the permanent magnet negative stiffness member 9 are arranged inside the housing 11. In the present embodiment, the actuator is the voice coil motor 10. The voice coil motor 10 serves as an actuator for active control. The actuator comprises a magnet 16 and a coil 17. The magnet 16 is suspended inside the housing 11 and fixed to the shaft 4, and is provided with a recess in the lower part. The coil 17 is disposed in the recess of the magnet 16, fixedly connected to the bottom of the housing 11, and connected to the control member.
The elastic member is fixedly provided on the upper surface of the housing 11. In this embodiment, the elastic member is a metal spring 6.
The shaft 4 sequentially passes through the executing component, the permanent magnet negative rigidity component 9, the upper surface of the shell 11 and the elastic component from bottom to top, and the bottom of the shaft 4 is suspended inside the shell 11.
The reference mass 2 is fixedly arranged on top of said shaft 4.
The relative displacement sensor 1 is fixedly arranged on the upper surface of the housing 11, and the relative displacement sensor 1 is used for measuring the relative displacement between the reference mass block 2 and the upper surface of the housing 11 to obtain a relative displacement signal.
The control part is connected with the relative displacement sensor 1and the execution part, and is used for generating a feedback control signal according to the relative displacement signal. The actuator is adapted to inhibit relative movement of the reference mass 2 and the housing 11 under the influence of the feedback control signal. And determining the absolute speed of the measured object after the relative displacement signal is subjected to feedback control. In this embodiment, the relative displacement signal is converted into an absolute velocity signal of the object under test by feedback control. Specifically, the feedback control signal is used to control the magnitude of the current applied to the voice coil motor coil.
Specifically, the measured object moves axially to drive the shell to move axially, the shell pushes the shaft to move axially through the spring, at the moment, the shell and the shaft move asynchronously, the relative displacement sensor measures the relative displacement of the shell and the shaft, and a voltage signal proportional to the relative displacement is output. The control part obtains a feedback control signal according to the voltage signal, and transmits the feedback control signal to the execution part to generate a feedback effect so as to influence the voltage signal output by the displacement sensor, and after countless feedback control, the voltage signal output by the displacement sensor reaches a steady state when the voltage signal output by the displacement sensor is equal to the voltage signal generated by the displacement sensor when the absolute speed signal input by the measured object and the feedback control signal generated by the current output signal of the displacement sensor act on the shaft together. The relative displacement signal after steady state is in direct proportion to the absolute speed of the measured object in the determined frequency band, and the absolute speed of the measured object is obtained.
Preferably, the permanent magnetic negative stiffness component 9 comprises a first permanent magnetic ring 12, a second permanent magnetic ring 13, a third permanent magnetic ring 14 and a fourth permanent magnetic ring 15.
The axes of the first permanent magnetic ring 12, the second permanent magnetic ring 13, the third permanent magnetic ring 14 and the fourth permanent magnetic ring 15 are the same. The shaft 4 passes through the axes of the first permanent magnet ring 12, the second permanent magnet ring 13, the third permanent magnet ring 14 and the fourth permanent magnet ring 15.
The inner diameter and the outer diameter of the first permanent magnetic ring 12 are equal to the inner diameter and the outer diameter of the second permanent magnetic ring 13, the inner diameter of the third permanent magnetic ring 14 is equal to the inner diameter and the outer diameter of the fourth permanent magnetic ring 15, and the inner diameter of the third permanent magnetic ring 14 is larger than the outer diameter of the first permanent magnetic ring 12.
The first permanent magnetic ring 12 and the second permanent magnetic ring 13 are fixed on the shaft 4, and the lower surface of the first permanent magnetic ring 12 is fixedly connected with the upper surface of the second permanent magnetic ring 13.
The third permanent magnetic ring 14 and the fourth permanent magnetic ring 15 are fixedly connected with the shell 11, and an axial gap is set between the third permanent magnetic ring 14 and the fourth permanent magnetic ring 15. Specifically, the axial gap between the third permanent magnet ring 14 and the fourth permanent magnet ring 15 depends on the magnetic field characteristics of the four permanent magnet rings and the degree of coupling between the first and second permanent magnet rings 12 and 13 and the third and fourth permanent magnet rings 14 and 15. In the present embodiment, the axial gap between the third permanent magnet ring 14 and the fourth permanent magnet ring 15=the axial heights of the first permanent magnet ring 12, the second permanent magnet ring 13, the third permanent magnet ring 14 and the fourth permanent magnet ring 15=10 mm.
The axial heights of the first permanent magnetic ring 12, the second permanent magnetic ring 13, the third permanent magnetic ring 14 and the fourth permanent magnetic ring 15 are equal. By adjusting the axial gap between the third permanent magnet ring 14 and the fourth permanent magnet ring 15, the negative stiffness range and the acting strength of the permanent magnet negative stiffness component 9 can be adjusted. The magnetizing direction of the permanent magnet ring is shown in fig. 3, and the solid arrow direction in the drawing represents the magnetizing direction.
The permanent magnet negative stiffness component 9 adopts 4 permanent magnet rings, and has the characteristics of small volume and compact structure compared with other negative stiffness structures. The magnetic force and the negative rigidity strength are flexible and configurable by adjusting the axial gap between the third permanent magnetic ring 14 and the fourth permanent magnetic ring 15 and the distance between the third permanent magnetic ring 14 and the fourth permanent magnetic ring 15 and the first permanent magnetic ring 12 and the second permanent magnetic ring 13.
The invention solves the problems of insufficient low-frequency measurement bandwidth and strong nonlinearity of the magnetic spring of the traditional mechanical spring-based sensor, and improves the stability and low-frequency performance of the sensor. Through mutual matching and structural optimization of the permanent magnet rings, the natural frequency of the sensor is reduced, and the problem of electromagnetic negative rigidity constant current heating is avoided.
In order to restrict the movement direction of the shaft 4, the permanent magnet negative rigidity active absolute speed sensor also comprises an air bearing guide rail. The air bearing rail is fixed inside the housing 11. The shaft passes through the air bearing rail. In this embodiment, the number of air bearing rails is two, a first air bearing rail 7 and a second air bearing rail 8. The permanent magnet negative stiffness component 9 is arranged between the first air bearing guide rail 7 and the second air bearing guide rail 8. Namely, the shaft 4 sequentially passes through the execution part, the second air bearing guide rail 8, the permanent magnet negative rigidity part 9, the first air bearing guide rail 7, the upper surface of the shell 11 and the elastic part from bottom to top.
Further, the permanent magnet negative stiffness active absolute speed sensor also comprises an axial adjusting nut 5. The axial adjustment nut 5 is arranged between the reference mass 2 and the metal spring 6. The shaft 4 passes through the axial adjustment nut 5. The axial adjustment nut 5 is used to adjust the initial position of the shaft 4.
In order to ensure that the relative displacement sensor 1 is in a proper measuring range, the permanent magnet negative stiffness active absolute speed sensor also comprises a linear displacement guide rail 3. The relative displacement sensor 1 is fixed to the upper surface of the housing 11 via a linear displacement guide 3. The initial relative position between the relative displacement sensor 1 and the reference mass 2 is adjusted by the linear displacement guide 3 to ensure that the relative displacement sensor 1 is within the proper measuring range. In this embodiment, the relative displacement sensor 1 is located at an upper position of the reference mass 2, and the relative displacement between the reference mass 2 and the upper surface of the housing 11 can be determined by measuring the change value of the distance between the lower surface of the relative displacement sensor 1 and the upper surface of the reference mass 2, i.e. the relative displacement, and determining the absolute velocity of the measured object 18 after feedback control. The relative displacement sensor 1 is actively controlled to provide a control input.
In this embodiment, the dashed line in fig. 2 is defined as the Z direction, which is also the axial direction of the central axis in fig. 1, and the direction indicated by the arrow is the positive direction of the Z direction.
The first permanent magnet ring 12 and the second permanent magnet ring 13 in the permanent magnet negative stiffness component 9, the magnet 16 of the voice coil motor 10, the reference mass block 2 and the axial adjusting nut 5 are connected together through the shaft 4 to form an inertial reference point. The shaft 4 passes through a metal spring 6 and two air bearing rails, and can only move along the Z direction under the restraint of the air bearing rails. The inertial reference point is supported by the metal spring 6 and is in non-contact with the housing 11, forming a spring mass vibrator movable along the Z-axis direction. The spring mass vibrator is composed of a reference mass block 2, a shaft 4, an axial adjusting nut 5, a first permanent magnet ring 12, a second permanent magnet ring 13 and a magnet 16 of a voice coil motor 10, and the axial movement state of any point on the spring mass vibrator is completely consistent, namely the displacement of any point in the axial direction is completely consistent, namely the relative displacement of any point and the lower surface of the relative displacement sensor 1 is completely consistent. Therefore, any point on the entire spring mass vibrator can be considered as an inertial reference point. The shell 11 is connected with the measured object 18, and the absolute speed information of the measured object 18 is finally obtained after feedback control by measuring the relative displacement of the spring mass vibrator and the shell 11.
Further, as shown in fig. 4, the control part includes a signal conditioning module, a feedback control module, and a driving module.
The signal conditioning module is connected with the relative displacement sensor 1. The signal conditioning module is used for converting the relative displacement signal into a voltage signal according to the gain of the relative displacement sensor 1 and the turning angle frequency of the relative displacement sensor 1. Specifically, the conditioning module converts the charge signal output by the relative displacement sensor 1 into a voltage signal proportional to the relative displacement.
The feedback control module is connected with the signal conditioning module. The feedback control module is used for determining a control voltage signal by adopting a differential controller, a low-frequency stabilizing filter, a differential strength adjusting filter and a high-frequency dynamic suppression filter.
The driving module is connected with the feedback control module and the executing component. The driving module is used for determining a feedback control signal according to the thrust constant of the voice coil motor and the control voltage signal. The feedback control signal is used to control the magnitude of the current applied to the voice coil motor. The voice coil motor inhibits relative movement of the reference mass and the housing under the influence of a feedback control signal. The driving module converts the control voltage signal output by the feedback control module into force to restrain the motion of the reference mass block, and further converts the relative displacement signal into an absolute speed signal of the measured object.
In this embodiment, the driving module is a driving circuit of the voice coil motor.
Through configuration design and parameter configuration of the permanent magnet negative stiffness component (axial distance between the third permanent magnet ring and the fourth permanent magnet ring, axial distance between the first permanent magnet ring and the second permanent magnet ring, radial gaps between the third permanent magnet ring and the fourth permanent magnet ring, and the size of the first permanent magnet ring, the second permanent magnet ring, the third permanent magnet ring and the size of the fourth permanent magnet ring), the stiffness of the active absolute velocity sensor is reduced by utilizing the compact structure characteristic of the permanent magnet negative stiffness component, the expansion of the low-frequency measurement bandwidth of the sensor is realized under the small volume, the movement of the reference mass block is restrained by combining with a corresponding active control strategy, the relative displacement between the permanent magnet rings in the permanent magnet negative stiffness component is reduced, so that the nonlinear problem of the sensor is improved, the further drifting trend caused by installation errors is restrained, and the low-frequency performance of the sensor is improved.
For a better understanding of the solution of the present invention, the active control strategy of the sensor of the present invention is specifically described below.
As shown in FIG. 5, in whichThe input speed (m/s) of the shell, namely the speed of the measured object, x-w represents the output relative displacement (m) of the reference mass block and the shell, u i represents the voltage signal (V) output by the signal conditioning module, u a represents the control voltage signal (V) output by the feedback control module, and f a represents the force (N) acting on the spring mass vibrator by the driving module.
P.R represents the transfer function of the housing velocity without a feedback path to the relative displacement of the reference mass and the housing. Where p= -ms is the forward path, representing the transfer function of the inertial force of the shell velocity transferred to the mass vibrator by passive elements like springs, damping etc.Is the controlled object and represents the transfer function of the force acting on the mass vibrator to the relative displacement of the reference mass and the housing. m represents the total mass of the spring mass vibrator, c represents the equivalent damping of the whole mechanical system, k represents the equivalent stiffness of the whole mechanical system, and s represents the Laplacian operator.
G rd denotes the transfer function of the relative displacement of the reference mass and the housing to the signal conditioning module output voltage.Where a rd represents the gain of the relative displacement sensor and ω rd represents the turning angular frequency of the relative displacement sensor.
G m denotes a transfer function of the output voltage of the feedback control module to the force of the voice coil motor acting on the mass vibrator,A vc represents the thrust constant of the voice coil motor, A ac represents the gain of the driving circuit, and ω ac represents the turning angular frequency of the driving circuit. H vc(s) denotes a voice coil motor portion of the actuator, and H ac(s) denotes a driving circuit portion of the actuator.
W represents a transfer function from the output voltage of the signal conditioning module to the output voltage of the feedback control module, and a control strategy in the feedback controller module is expressed as follows in a frequency domain:
ua＝ui*W(s)。
Wherein W(s) represents a feedback control strategy and comprises four parts of a differential controller, a low-frequency stabilizing filter, a differential strength adjusting filter and a high-frequency dynamic suppression filter. The differential controller is used for converting the relative displacement of the shell and the reference mass block into the relative speed, A p is differential control gain and adjusts control intensity, the low-frequency stabilizing filter comprises two functions, the low-frequency stabilizing filter is combined with the differential controller in the frequency range from direct current frequency to omega in and used for controlling input attenuation of the frequency range to avoid integral saturation, and integral action is generated in the frequency range from omega in to omega c1 and drift of the reference mass block is restrained. Omega c1 is a key frequency point, and the control strength of the low-frequency bandwidth and the drift suppression of the active absolute speed sensor needs to be considered. The differential strength adjusting filter is used for adjusting the differential strength corresponding to different frequency bands, so that the influence of the low-frequency stabilizing filter is counteracted between omega c1 and omega c2, a stable differential effect is generated, the differential effect is enhanced between omega c2 and omega bh, the tracking and response of the voice coil motor to high-frequency control signals are improved, the inhibition capability to the motion of the reference mass block is enhanced, the high-frequency dynamic inhibition filter attenuates the control input in a frequency range higher than omega bh, and the response of the feedback control module to high-frequency dynamic is inhibited. A schematic diagram of the frequency response of W(s) is shown in fig. 6.
The overall work transfer function of the active absolute speed sensor is then:
As shown in fig. 7, the control method of the permanent magnet negative stiffness active absolute speed sensor of the invention comprises the following steps:
S1, fixing the lower surface of the shell on a tested object.
And S2, when the measured object moves, the reference mass block is displaced under the action of the shaft, and the relative displacement between the reference mass block and the upper surface of the shell is acquired through a relative displacement sensor, so that a relative displacement signal is obtained.
And S3, generating a feedback control signal according to the relative displacement signal, and controlling an execution part to inhibit the relative movement of the reference mass block and the shell so as to convert the relative displacement signal into an absolute speed signal of the measured object. The absolute speed of the measured object is obtained after the relative displacement signal is subjected to feedback control.
Specifically, the relative displacement signal is firstly converted into a voltage signal according to the gain of the relative displacement sensor and the turning angular frequency of the relative displacement sensor. In this embodiment, the following formula is used to convert the relative displacement signal into a voltage signal:
Wherein u i is a voltage signal, A rd is a gain of the relative displacement sensor, ω rd is a turning angular frequency of the relative displacement sensor, s is a Laplacian, and x-w is a relative displacement between the reference mass and the housing.
And then determining a control voltage signal by adopting a differential controller, a low-frequency stabilizing filter, a differential intensity adjusting filter and a high-frequency dynamic suppression filter according to the voltage signal. The control voltage signal is determined using the following equation:
Where u a is a control voltage signal, u i is a voltage signal, a p is a differential control gain, s is a laplace operator, and ω in、ωc1、ωc2、ωbh are all frequency points.
And finally, determining a feedback control signal according to the thrust constant of the voice coil motor, the gain of the driving circuit, the turning angle frequency of the driving circuit and the control voltage signal. The feedback control signal is used to control the magnitude of the current applied to the voice coil motor.
The voice coil motor suppresses the motion of the reference mass under the influence of a feedback control signal. Since the coil of the voice coil motor generates a force when placed in a magnetic field, the magnitude of the force is proportional to the current applied to the coil. Thus, the force of the voice coil motor on the spring mass array can be determined based on the magnitude of the current applied to the coil. Specifically, the force of the voice coil motor on the spring mass array is determined using the following formula:
Wherein f a is the force of the voice coil motor acting on the spring mass array, A vc is the thrust constant of the voice coil motor, A ac is the gain of the driving circuit, and ω ac represents the turning angular frequency of the driving circuit.
The active control strategy implemented in the feedback control module of the invention utilizes the measurement result of the relative displacement sensor to drive the voice coil motor to compensate the control of the reference mass block through the processing of the control algorithm. With the adoption of the frequency division design, at the frequency higher than omega in, the algorithm shows an integral effect for suppressing the drift of the reference mass block. Meanwhile, the problem of integral saturation instability caused by direct current components of the relative displacement sensor in the frequency band is comprehensively balanced and considered, and a low-frequency stable filter in the feedback control module is designed. The differential control by utilizing the relative displacement information is shown in the frequency range from omega c1 to omega bh, the relative damping is applied to the reference mass block, the relative movement of the reference mass block and the shell is effectively restrained, and the low-frequency measurement bandwidth is expanded. Meanwhile, the offset problem of the integral control effect on the differential control of the frequency band is comprehensively considered, the high-frequency cut-off frequency of the differential effect is determined according to the high-frequency dynamic characteristic and the effective dynamic range of the control system signal, the high-frequency noise of the control system is restrained, and the stability is improved. The method is characterized by comprising a differential controller in a feedback control module, a differential intensity adjusting filter and a high-frequency dynamic suppression filter.
In the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, and identical and similar parts between the embodiments are all enough to refer to each other.
The principles and embodiments of the present invention have been described herein with reference to specific examples, which are intended to facilitate an understanding of the principles and concepts of the invention and are to be varied in scope and detail by persons of ordinary skill in the art based on the teachings herein. In view of the foregoing, this description should not be construed as limiting the invention.
Claims (8)
1. A permanent magnet negative stiffness active absolute velocity sensor for measuring an absolute velocity of a measured object, the permanent magnet negative stiffness active absolute velocity sensor comprising:
the lower surface of the shell is fixedly arranged on the tested object;
an execution part arranged inside the shell;
The permanent magnet negative stiffness component is arranged in the shell;
the elastic component is fixedly arranged on the upper surface of the shell;
the shaft sequentially passes through the execution part, the permanent magnet negative stiffness part, the upper surface of the shell and the elastic part from bottom to top, and the bottom of the shaft is suspended in the shell;
a reference mass fixedly disposed on top of the shaft;
The relative displacement sensor is fixedly arranged on the upper surface of the shell and is used for measuring the relative displacement between the reference mass block and the upper surface of the shell to obtain a relative displacement signal;
The control component is connected with the relative displacement sensor and the execution component and is used for generating a feedback control signal according to the relative displacement signal;
The execution component is used for inhibiting the relative movement of the reference mass block and the shell under the action of the feedback control signal, and determining the absolute speed of the measured object after the relative displacement signal is subjected to feedback control;
The executing component comprises a magnet and a coil;
the magnet is suspended in the shell, fixed with the shaft and provided with a groove at the lower part;
the coil is arranged in the groove of the magnet, fixedly connected with the bottom of the shell and connected with the control part;
the feedback control signal is used for controlling the magnitude of current applied to the coil;
the permanent magnet negative stiffness component comprises a first permanent magnet ring, a second permanent magnet ring, a third permanent magnet ring and a fourth permanent magnet ring;
The axes of the first permanent magnetic ring, the second permanent magnetic ring, the third permanent magnetic ring and the fourth permanent magnetic ring are the same, and the shaft penetrates through the axes of the first permanent magnetic ring, the second permanent magnetic ring, the third permanent magnetic ring and the fourth permanent magnetic ring;
The inner diameter and the outer diameter of the first permanent magnetic ring are equal to the inner diameter and the outer diameter of the second permanent magnetic ring, the inner diameter of the third permanent magnetic ring is larger than the outer diameter of the first permanent magnetic ring, and the inner diameter of the third permanent magnetic ring is equal to the outer diameter of the fourth permanent magnetic ring;
The first permanent magnet ring and the second permanent magnet ring are fixed on the shaft, and the lower surface of the first permanent magnet ring is fixedly connected with the upper surface of the second permanent magnet ring;
The third permanent magnet ring and the fourth permanent magnet ring are fixedly connected with the shell, and an axial gap is set between the third permanent magnet ring and the fourth permanent magnet ring.
2. The permanent magnet negative stiffness active absolute velocity sensor of claim 1, wherein the actuator is a voice coil motor.
3. The permanent magnet negative stiffness active absolute velocity sensor according to claim 1, wherein the axial heights of the first permanent magnet ring, the second permanent magnet ring, the third permanent magnet ring, and the fourth permanent magnet ring are equal.
4. The permanent magnet negative stiffness active absolute velocity sensor of claim 1, wherein the resilient member is a metal spring.
5. The permanent magnet negative stiffness active absolute velocity sensor of claim 1, further comprising an air bearing rail;
the air bearing guide rail is fixed in the shell, the shaft penetrates through the air bearing guide rail, and the air bearing guide rail is used for restraining the movement direction of the shaft.
6. The permanent magnet negative stiffness active absolute speed sensor of claim 1, further comprising an axial adjustment nut;
The axial adjusting nut is arranged between the reference mass block and the elastic component, the shaft penetrates through the axial adjusting nut, and the axial adjusting nut is used for adjusting the initial position of the shaft.
7. A control method of a permanent magnet negative stiffness active absolute speed sensor for controlling the permanent magnet negative stiffness active absolute speed sensor according to any one of claims 1 to 6, characterized in that the control method of the permanent magnet negative stiffness active absolute speed sensor comprises:
Fixing the lower surface of the shell on a measured object;
when the measured object moves, the reference mass block is displaced under the action of the shaft, and the relative displacement between the reference mass block and the upper surface of the shell is acquired through the relative displacement sensor, so that a relative displacement signal is obtained;
and generating a feedback control signal according to the relative displacement signal, controlling an execution part to restrain the relative motion of the reference mass block and the shell, and determining an absolute speed signal of the measured object after the relative displacement signal is subjected to feedback control.
8. The control method of a permanent magnet negative stiffness active absolute speed sensor according to claim 7, wherein the executing component is a voice coil motor;
the control execution part suppresses the relative motion of the reference mass block and the shell, and specifically comprises:
converting the relative displacement signal into a voltage signal according to the gain of the relative displacement sensor and the turning angle frequency of the relative displacement sensor;
According to the voltage signal, a differential controller, a low-frequency stabilizing filter, a differential intensity adjusting filter and a high-frequency dynamic suppression filter are adopted to determine a control voltage signal;
and determining a feedback control signal according to the thrust constant of the voice coil motor, the gain of the driving circuit, the turning angle frequency of the driving circuit and the control voltage signal, wherein the feedback control signal is used for controlling the current applied to the voice coil motor, and the voice coil motor inhibits the movement of the reference mass block under the action of the feedback control signal.
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| US5829732A (en) * | 1996-03-27 | 1998-11-03 | Toyo Tire & Rubber Co., Ltd. | Exhaust pipe supporting device |
| CN109716143A (en) * | 2016-07-27 | 2019-05-03 | 卢米达因科技公司 | The rotary motion of inertial sensor is converted to the linear movement of its inspection quality block |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2008190943A (en) * | 2007-02-02 | 2008-08-21 | Kazuto Sedo | Absolute displacement-speed measuring sensor |
| JP2010084814A (en) * | 2008-09-30 | 2010-04-15 | Psc Kk | Vibration eliminating device |
| CN102537196B (en) * | 2010-12-24 | 2013-12-18 | 上海微电子装备有限公司 | Active vibration damping system as well as vibration damping unit and absolute displacement measuring device thereof |
| US10753770B2 (en) * | 2018-11-07 | 2020-08-25 | Shanghai University | Electromagnetic type quasi-zero stiffness absolute displacement sensor |
| CN112597611B (en) * | 2020-12-28 | 2021-11-09 | 哈尔滨工程大学 | Electromagnetic force control method of magnetic disc type negative stiffness electromagnetic actuating mechanism |
| CN113091587B (en) * | 2021-04-06 | 2022-04-29 | 重庆大学 | A Quasi-Zero Stiffness Absolute Displacement Sensor Based on Electromagnetic Positive Stiffness |
| CN113324465B (en) * | 2021-06-01 | 2022-12-09 | 长沙理工大学 | Absolute displacement sensor and design method thereof |
| CN114371308B (en) * | 2022-01-14 | 2022-08-30 | 上海大学 | Magnetic suspension absolute speed sensor |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5829732A (en) * | 1996-03-27 | 1998-11-03 | Toyo Tire & Rubber Co., Ltd. | Exhaust pipe supporting device |
| CN109716143A (en) * | 2016-07-27 | 2019-05-03 | 卢米达因科技公司 | The rotary motion of inertial sensor is converted to the linear movement of its inspection quality block |
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