Low-frequency micro-vibration sensing and actuating integrated deviceTechnical Field
The invention belongs to the technical field of space low-frequency measurement and active vibration isolation, and particularly relates to a low-frequency micro-vibration sensing and actuating integrated device.
Background
During the on-orbit operation of the spacecraft, the load carried on the spacecraft is influenced by the space micro-vibration disturbing force. The low-frequency micro-vibration such as the vibration of a flexible accessory, the vibration of a flexible solar panel, the vibration of the sweep of an optical camera and the like are mainly concentrated at 0.01-10 Hz. The low-frequency micro-vibration has obvious influence on important performance indexes such as pointing precision, stability, resolution and the like of a space precision load. Therefore, the development of spatial low-frequency micro-vibration measurement and active vibration isolation technology research is one of important technologies for ensuring reliable operation of precise loads.
Low frequency dynamic force sensors are an important way of low frequency micro-vibration measurement. Currently, low frequency dynamic force sensors mainly include piezoelectric and resistive strain types. The signal generated by the piezoelectric sensor is weak, the output impedance is high, and the signal can be acquired only after the high output impedance is changed into low output impedance and then charge amplification is carried out. When static measurements are made, the amount of charge is easily lost, and over time the functional relationship between the amount of charge and pressure changes. Thus, the lower the measured frequency, the more the output voltage sensitivity deviates from ideal, and the greater the error in sensitivity and phase angle. Strain type sensors are mainly used for measuring static and quasi-static forces and are widely used because of their simple design and stable and reliable performance. However, there is still a problem of insufficient sensitivity in measuring dynamic forces. Accordingly, there is a need in the art for a device suitable for spatial low frequency micro-vibration measurement and active vibration isolation that ensures reliable operation of spatially accurate loads.
Disclosure of Invention
In view of this, the present invention proposes a low-frequency micro-vibration sensing and actuating integrated device. The low-frequency dynamic force sensor adopts a strain measurement principle to convert the received low-frequency dynamic force into an electric signal acquired by strain. The semiconductor strain gauge with the sensitivity coefficient higher than that of a common strain gauge is adopted as a measuring element, the polyurethane material with the elasticity modulus far lower than that of metal is adopted as an elastic element, and the composite full-bridge circuit is adopted as a measuring circuit, so that the sensitivity of the sensor can be effectively improved, and the accurate measurement of a low-frequency signal of 0.01-10Hz can be realized. The voice coil actuator outputs a corresponding force according to a signal provided by the controller. The voice coil actuator has the advantages of quick response, high precision, low energy consumption and the like, and can realize accurate control of force values. According to the invention, the low-frequency dynamic force sensor and the voice coil actuator are integrated, so that the accurate measurement and response of the low-frequency dynamic force of the mounting platform are realized.
On one hand, the invention provides a low-frequency micro-vibration sensing and actuating integrated device which is characterized by comprising a top component, a voice coil actuator, a low-frequency dynamic force sensor and a bottom component, wherein the voice coil actuator comprises magnetic steel and a voice coil, the voice coil is arranged on the bottom component, the magnetic steel is arranged on the top component, one end of the low-frequency dynamic force sensor is connected with the voice coil, the other end of the low-frequency dynamic force sensor is connected with the magnetic steel, the low-frequency dynamic force sensor is coaxially connected with the voice coil actuator, and the low-frequency dynamic force sensor comprises a semiconductor strain gauge serving as a measuring element, a polyurethane material serving as an elastic element and a composite full-bridge circuit serving as a measuring circuit.
Further, the voice coil is mounted on the bottom member through a bolt, the magnetic steel is mounted on the top member through a bolt, one end of the low-frequency dynamic force sensor is connected with the voice coil through a bolt, and the other end of the low-frequency dynamic force sensor is connected with the magnetic steel through epoxy glue.
Further, the semiconductor strain gauge is a TP-5 semiconductor strain gauge made of monocrystalline silicon.
Further, the semiconductor strain gauge has an outer diameter of 15mm and a height of 30mm.
Further, the elastic modulus of the polyurethane material is 4.1×107 Pa.
Further, the compound full-bridge circuit uses 8 semiconductor strain gages to be symmetrically stuck around the elastic element.
Further, the magnetic steel comprises a permanent magnet and a stator core, wherein the permanent magnet is a Ru-Fe-B permanent magnet N42SH, and the stator core is stainless steel with the steel number of 2Cr13.
Further, the voice coil comprises a coil and a voice coil framework, wherein the coil adopts an annular multi-layer winding, and is wound by high-strength enameled wires QY-2/220, and the voice coil framework is made of 6061 aluminum alloy.
Further, the coil is connected with the magnetic steel through the low-frequency dynamic force sensor, and the height H of the voice coil and the gap H between the voice coil and the magnetic steel are designed according to vibration isolation requirements, so that the motion stroke of the voice coil actuator is guaranteed to be H.
On the other hand, the invention also provides active vibration isolation equipment, which comprises the low-frequency micro-vibration sensing and actuating integrated device, a power supply, a signal conditioner, a real-time controller and a voice coil driver, wherein the power supply is used for providing power for the active vibration isolation equipment, the signal conditioner is in data connection with the low-frequency micro-vibration sensing and actuating integrated device and the real-time controller, the real-time controller is further electrically connected with the voice coil driver, and the voice coil driver is further electrically connected with the low-frequency micro-vibration sensing and actuating integrated device;
The active vibration isolation device comprises a low-frequency dynamic force sensor, a signal conditioner, a real-time controller and a voice coil driver, wherein the low-frequency dynamic force sensor is used for converting a force value signal into voltage and transmitting the voltage to the signal conditioner when the top member is disturbed by dynamic force F, the signal conditioner outputs the signal to the real-time controller to collect information of the force value F received by the low-frequency dynamic force sensor in real time, and the real-time controller outputs control current to the voice coil driver through calculation of a control algorithm so as to drive the voice coil actuator to output control force to perform vibration control on the top member, so that the stable state of the top member is realized.
The sensing vibration isolation system comprises a sensor for measuring and an actuator for outputting force, and when the vibration isolation system is designed, not only the sensor and the actuator are required to be respectively designed in structure, but also the installation position of the sensor and the actuator is required to be designed. The low-frequency micro-vibration sensing and actuating integrated device effectively combines the sensor and the actuator, can simultaneously provide two functions of low-frequency vibration measurement and actuating power output, and is convenient for developing a vibration isolation system.
The low-frequency micro-vibration sensing and actuating integrated device designed by the invention can accurately measure the information of the low-frequency force value of 0.01-10Hz and can control the vibration of the mounting platform. This makes the invention in practical application, compared with the prior art, has the following beneficial effects:
1. The sensor performance is improved by adopting a semiconductor strain gauge as a measuring element, a polyurethane material as an elastic element and a composite full-bridge circuit as a measuring circuit, so that the sensitivity of the sensor reaches 0.33V/N and the measuring frequency reaches 0.01Hz.
2. The vibration isolation performance of the device is improved, the device can not only measure the force value information of the mounting platform, but also output the force value to perform active vibration isolation on the mounting platform, and the polyurethane material connected with the sensor and the actuator has the characteristics of a spring and damping, and can also perform passive vibration isolation on the mounting platform.
3. The stability of the actuator is improved, namely the magnetic steel of the voice coil actuator and the coil part are connected by the elastic element of the sensor, so that the voice coil actuator has great damping, the passive vibration isolation performance can be improved, the design difficulty of an active vibration isolation algorithm can be reduced, and the fault condition can be reduced.
4. The environmental adaptability of the device is improved, and all materials in the device can meet the environmental requirements of minus 45 ℃ to +100 ℃ and can meet the severe environmental requirements of space.
5. The cost is reduced, the cost of the semiconductor strain gauge used by the sensor is similar to that of a common strain gauge, the material cost and the processing cost of the polyurethane elastic element are far lower than those of the metal elastic element, and the magnetic steel and the coil used by the voice coil actuator are mature processes, so that the cost of the low-frequency micro-vibration sensing and actuating integrated device can be effectively reduced.
Drawings
FIG. 1 is a perspective view of the assembly and connection of the low frequency sensing and actuation integrated device of the present invention.
FIG. 2 is a schematic diagram of a low frequency sensing and actuation integrated device according to the present invention.
Fig. 3 is a front view and a cross-sectional view of the low frequency sensing and actuation integrated device of the present invention.
Fig. 4 is a schematic structural view of the low frequency dynamic force sensor of the present invention.
Fig. 5 is a schematic diagram of an elastic element in the low frequency dynamic force sensor of the present invention.
Fig. 6 is a schematic view of a semiconductor strain gauge attachment position in accordance with the present invention.
Fig. 7 is a schematic diagram of a semiconductor strain gauge wiring circuit in accordance with the present invention.
Fig. 8 is a schematic structural view of the magnetic steel in the present invention.
Fig. 9 is a front view and a cross-sectional view of the magnetic steel in the present invention.
Fig. 10 is a schematic structural view of a voice coil according to the present invention.
Fig. 11 is a front view and a sectional view of a voice coil in the present invention.
Fig. 12 is a design position diagram of the voice coil actuator of the present invention.
Fig. 13 is a schematic view of the operation of the active vibration isolation apparatus of the present invention including the low frequency micro-vibration sensing and actuation integrated device.
In the figure, a 1-stator core, a 2-permanent magnet, a 3-coil, a 4-voice coil framework, a 5-bottom member, a 6-elastic element, a 7-semiconductor strain gauge and an 8-top member.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in more detail below with reference to the accompanying drawings, but the present invention is not limited thereto.
The invention designs the low-frequency dynamic force sensor based on the strain measurement principle, designs the voice coil actuator based on the electromagnetic principle, designs the low-frequency dynamic force sensor and the voice coil actuator into an integrated structure, and can also provide output of force values in the process of measuring dynamic force.
The invention relates to a structure perspective view of a low-frequency micro-vibration sensing and actuating integrated device, which is shown in fig. 1. The low-frequency micro-vibration sensing and actuating integrated device comprises a voice coil actuator and a low-frequency dynamic force sensor. The voice coil actuator comprises magnetic steel and a voice coil, wherein the magnetic steel mainly comprises a stator core 1 and a permanent magnet 2. The voice coil mainly comprises a coil 3 and a voice coil frame 4. The voice coil skeleton is mounted on the bottom member 5 by bolts, and the stator core of the magnetic steel is mounted on the top member 8 by bolts. The low-frequency dynamic force sensor mainly comprises an elastic element 6 and a semiconductor strain gauge 7, wherein one end of the elastic element 6 is connected with a voice coil framework through a bolt, and the other end of the elastic element is connected with a magnetic steel permanent magnet through epoxy glue. The voice coil actuator is coaxially connected with the force sensor. The force sensor can measure dynamic force F applied to the top component, the elastic element of the force sensor has the characteristics of a spring and damping, passive vibration isolation can be provided for the top plate, and the voice coil actuator can actively isolate the top component. The structure of the low frequency sensing and actuation integrated device is shown in fig. 2-3.
In one embodiment, the body structure of the low frequency dynamic force sensor is a cylindrical elastic element, and the strain gage is adhered to the surface of the elastic element. The sensitive grid of the strain gauge also obtains the same deformation along with the stress deformation of the elastic element, so that the resistance of the sensitive grid is changed along with the deformation of the elastic element, the resistance change is proportional to the strain of the elastic element, and the resistance change is converted into voltage change through a bridge measuring circuit, so that the strain quantity of the elastic element is obtained. And finally, calculating the stress value of the elastic element through Hooke's law. The structure of the low frequency dynamic force sensor and the elastic element entity are shown in fig. 4-5.
In order to improve the sensitivity of the low-frequency dynamic force sensor, polyurethane materials are adopted as elastic elements of the low-frequency dynamic force sensor, and the elastic modulus is 4.1 multiplied by 107 Pa, which is one thousandth of the elastic modulus of metal. Compared with a metal material, the polyurethane material has higher elasticity and higher damping, and can effectively provide passive vibration isolation performance. In order to facilitate the adhesion of the strain gauge, the outer diameter is designed to be 15mm and the height is designed to be 30mm. The polyurethane material processed elastomer is shown in figure 4.
The traditional strain sensor mainly uses a metal strain gauge as a measuring element, has low sensitivity coefficient and long response time, and cannot dynamically measure. In a preferred embodiment, the low frequency dynamic force sensor uses a TP-5 semiconductor strain gauge made of monocrystalline silicon, the detailed parameters are shown in Table 1. The semiconductor strain gauge is a sensitive element made of piezoresistance effect of semiconductor monocrystalline silicon, and has the advantages of small mechanical hysteresis, small volume and low power consumption. The semiconductor strain gauge has better temperature stability and wider working temperature range than the traditional metal strain gauge, and can work normally within the range of-55-200 ℃. The response time of the semiconductor strain gauge is faster than that of the metal strain gauge, and the strain change of the object can be reflected in microseconds. The sensitivity coefficient is higher and is 50 times that of a common metal strain gauge.
TABLE 1 parameters of TP-5 semiconductor Strain gauge
The measuring circuit adopts a composite full-bridge connection mode, 8 semiconductor strain gages are symmetrically stuck around the elastomer, and the bridge circuit can furthest improve the sensitivity of the sensor, effectively reduce strain errors caused by unbalanced load and has a temperature compensation function. The attachment position and the connection mode of the strain gauge are shown in fig. 6-7.
It can be seen from the principle of strain measurement that the strain epsilon11 of the single strain gage and the total strain measured using a full bridge circuitThe relation between the two is:
Wherein epsilon11,ε12,ε21,ε22,ε31,ε32,ε41,ε42 is the strain value of the strain gauge R11,R12,R21,R22,R31,R32,R41,R42, epsilonT is the strain value corresponding to temperature; Is a measurement of the full bridge and μ is the poisson's ratio of the elastomeric material of the low frequency dynamic force sensor. From equation (1), it can be seen that the strain value εT and the full bridge measurement value corresponding to the temperatureIndependent, full bridge measurementMuch greater than using a single strain gage measurement epsilon11. Therefore, the measured value obtained by adopting the composite full-bridge connection mode can not only effectively improve the sensitivity of the sensor, but also inhibit the influence caused by the ambient temperature.
The voice coil actuator adopts a cylindrical linear voice coil motor scheme and mainly comprises two parts of magnetic steel and a voice coil, and the structure of the voice coil actuator is shown in figures 5-7. The magnetic steel adopts an inner cylindrical magnetic steel structure and mainly comprises a permanent magnet and a stator core. The cylindrical permanent magnet is adhered in the magnetic steel groove by epoxy resin glue, and is characterized by axial magnetization, compact and firm structure and favorable improvement of the structural strength of the magnetic steel. The permanent magnet adopts high-performance Ru Tiepeng permanent magnet N42SH, and has high magnetic energy product, thereby being beneficial to improving the motor force density. The magnetic steel iron core adopts magnetic conduction stainless steel, steel grade 2Cr13, and can simultaneously ensure magnetic conduction performance and structural strength. The structure of the magnetic steel is shown in fig. 8-9.
The voice coil mainly comprises a coil and a voice coil framework. The coil adopts an annular multilayer winding, is wound by high-strength enameled wires QY-2/220, and the voice coil framework material is 6061 aluminum alloy. The voice coil is connected with the magnetic steel through the force sensor, and the height H of the voice coil part and the gap H between the voice coil and the magnetic steel can be designed according to vibration isolation requirements, so that the motion stroke of the voice coil actuator is guaranteed to be H. The voice coil is constructed as shown in fig. 10-11, and the design position of the voice coil actuator is shown in fig. 12.
The operation of the low frequency micro-vibration sensing and actuation integrated device is shown in fig. 13. When the top member is disturbed by the dynamic force F, the low frequency dynamic force sensor is forced to deform, converting the force value signal into a voltage, and transmitting the voltage to the signal conditioner. The signal conditioner outputs signals to the real-time controller, and information of the force value F received by the low-frequency dynamic force sensor can be collected in real time. The real-time controller outputs control current to the voice coil driver through calculation of a control algorithm, and drives the voice coil actuator to output control force to perform vibration control on the top component, so that the stable state of the top component can be realized.
The invention also provides active vibration isolation equipment, which comprises the low-frequency micro-vibration sensing and actuating integrated device, a power supply, a signal conditioner, a real-time controller and a voice coil driver, wherein the power supply is used for providing power for the active vibration isolation equipment, the signal conditioner is in data connection with the low-frequency micro-vibration sensing and actuating integrated device and the real-time controller, the real-time controller is further electrically connected with the voice coil driver, and the voice coil driver is further electrically connected with the low-frequency micro-vibration sensing and actuating integrated device;
The working process of the active vibration isolation device comprises that when the top component is disturbed by dynamic force F, the low-frequency dynamic force sensor is stressed and deformed, a force value signal is converted into voltage and transmitted to the signal conditioner, the signal conditioner outputs the signal to the real-time controller to collect information of the force value F received by the low-frequency dynamic force sensor in real time, the real-time controller outputs control current to the voice coil driver through calculation of a control algorithm, and accordingly the voice coil actuator is driven to output control force to perform vibration control on the top component, so that the stable state of the top component is achieved, and the voice coil actuator is shown in fig. 13.
It should be noted that the above-described examples are only preferred embodiments of the present invention. It will be apparent to those skilled in the art that various modifications, improvements, and equivalents may be made to the present invention without departing from the principles of the invention, and such modifications, improvements, and equivalents are considered to be within the scope of the claims.