CN117394608A - Displacement self-sensing device of electromagnetic actuator - Google Patents
Displacement self-sensing device of electromagnetic actuator Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01H11/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by detecting changes in electric or magnetic properties
- G01H11/06—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by detecting changes in electric or magnetic properties by electric means
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K11/00—Structural association of dynamo-electric machines with electric components or with devices for shielding, monitoring or protection
- H02K11/20—Structural association of dynamo-electric machines with electric components or with devices for shielding, monitoring or protection for measuring, monitoring, testing, protecting or switching
- H02K11/21—Devices for sensing speed or position, or actuated thereby
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K33/00—Motors with reciprocating, oscillating or vibrating magnet, armature or coil system
- H02K33/18—Motors with reciprocating, oscillating or vibrating magnet, armature or coil system with coil systems moving upon intermittent or reversed energisation thereof by interaction with a fixed field system, e.g. permanent magnets
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Abstract
The invention provides a displacement self-sensing device of an electromagnetic actuator, which adopts eddy current effect coupling between an inductance coil and a permanent magnet metal surface to perform displacement sensing. The invention realizes a drive circuit with displacement self-perception, which is characterized in that a low-frequency drive signal and a high-frequency sensing signal work simultaneously and do not interfere with each other, and the circuit consists of an inductance measuring unit, a drive unit, an isolation capacitor and an isolation inductor. The invention can drive the electromagnetic actuator and simultaneously acquire the inductance information of the coil, thereby converting the inductance information into the displacement information of the electromagnetic actuator. The flexible electromagnetic actuator prototype of the invention can generate motion exceeding 200 mu m, the displacement sensing resolution is as high as 0.034 mu m, and the displacement sensing resolution is tested on the traditional voice coil motor, thereby realizing motion travel of more than 2mm and displacement self-sensing with 0.16 mu m resolution.
Description
Technical Field
The invention relates to an electromagnetic actuator and the field of displacement sensing, in particular to a displacement self-sensing device of an electromagnetic actuator.
Background
The electromagnetic actuator operates by electromagnetic force between the permanent magnet and the inductance coil, and when current is supplied to the coil, attractive or repulsive magnetic force is generated between the magnetic field generated by the coil and the permanent magnet, thereby generating movement (displacement change) between the magnet and the coil. The power amplifier driving circuit amplifies an input signal to excite the electromagnetic actuator in a constant current source/constant voltage source mode. Conventional rigid electromagnetic actuators have many advantages including fast response, high power output, and easy displacement control. Voice coil motors are one of the most widely used electromagnetic actuators, and have been applied to devices such as auto-focus lenses, precision adaptive telescoping systems, and precision positioning tables for small cameras. In recent years, flexible electromagnetic actuators have wide prospects in applications in the fields of soft robots, haptic feedback devices, virtual Reality (VR) and Augmented Reality (AR) systems, medical instruments, human-machine interfaces, and the like.
Most available electromagnetic actuators require additional encoders or external sensors to provide displacement and force/torque information for feedback control, from hall effect sensors, grating scales, electro-optical rotary encoders to laser displacement sensors. These integrated encoders or external sensors can provide reliable sensing information for the electromagnetic actuator, but they also add cost, complexity and weight, bulk to the system. Heretofore, commercially available sensors have been incompatible with the deformable body of flexible electromagnetic actuators. Therefore, there is a great need for a self-sensing solution to develop smart devices and interactive interfaces based on flexible electromagnetic actuators.
The displacement sensor based on the eddy current effect adopts a detection coil which is excited by high frequency to generate induced eddy current in a target conductor, the change of the distance between the detection coil and a detected target is converted into the change of the impedance (including inductance and resistance) of the detection coil, and a signal conditioning circuit acquires displacement information by measuring the change of the parameter of the detection coil. Eddy current sensors are very widely used for displacement, vibration, angle and velocity, or thickness, resistivity and temperature measurements in various industrial sites and experimental studies. For synchronous driving and displacement/vibration measurement of high-resolution electromagnetic actuators, the components of the electromagnetic actuators are permanent magnets and induction coils, while displacement self-sensing based on the eddy current effect means that it is not necessary to integrate additional hardware into (or mount on) the actuator, so that the integration of a driving circuit and a signal conditioning circuit effectively reduces the complexity of the system in principle, which is important for miniaturization of intelligent devices and interactive interfaces. Due to the characteristics of the sensing principle of the eddy current effect, the sensor has the advantages of high stability, insensitivity to environmental pollution, wide working temperature range, wide frequency response, low price and the like.
For the self-sensing scheme of the rigid actuator, a scheme for monitoring driving current to estimate output torque and force is adopted at present, a mathematical model of the scheme is difficult to build, the condition of an application scene is limited, and the scheme is not flexible enough. Several methods are currently proposed to achieve self-sensing of displacement or deformation of a flexible actuator: 1. the shape memory coil actuator length is monitored using the deformation induced inductance change. 2. By combining a high-amplitude voltage driving circuit with a low-amplitude voltage capacitance measuring circuit, a hydraulic amplification self-healing electrostatic actuator is provided.
Disclosure of Invention
The invention aims to provide a displacement self-sensing device of an electromagnetic actuator, which can measure vibration/displacement while driving the electromagnetic actuator, and has good application prospect in widely used electromagnetic actuators and emerging intelligent systems based on flexible electromagnetic actuators.
The invention is realized by the following technical scheme:
a method for implementing synchronous driving and sensing on an electromagnetic actuator, the method being implemented by a system of an electromagnetic actuator consisting of a permanent magnet, an inductor, and a sensing-driving integrated circuit, the implementation comprising the steps of:
step 1), selecting a general electromagnetic actuator (voice coil motor) comprising an inductance coil, or manufacturing a flexible electromagnetic actuator comprising an inductance coil;
step 2), designing and manufacturing a sensing-driving integrated circuit, wherein the driving unit and the measuring unit can work independently and are not mutually influenced. As shown in fig. 1, the power amplification module can amplify the driving signal to generate a high-current excitation signal to drive the electromagnetic actuator to move, and the inductance measurement module can measure the inductance of the coil of the electromagnetic actuator under high frequency and output displacement information corresponding to the inductance.
Step 3), connecting an inductance coil of the electromagnetic actuator to the sensing-driving integrated circuit, connecting an output port of the signal generator to the sensing-driving integrated circuit as a driving signal, and connecting the output sensing signal to an external upper computer;
and 4) decoupling the sensing signal from the inductance information L of the inductance coil through an acquisition program written by the upper computer.
Step 5), calibrating a functional relation between the inductance information L and the actual displacement d by using the high-resolution displacement sensor so as to acquire real-time displacement information of the electromagnetic actuator:
L＝f(d)
further, the sensing-driving integrated circuit is characterized by comprising a driving unit and a measuring unit, wherein the driving unit and the measuring unit can amplify driving signals and measure inductance values of coils at the same time, and the sensing-driving integrated circuit can work independently and do not interfere with each other.
Further, the driving unit is characterized in that the driving part comprises a power amplifier module and two isolation inductors.
Furthermore, the measuring unit is characterized by comprising a high-resolution inductance measuring unit and an isolation capacitor.
Furthermore, a metal coating is arranged on the surface of a permanent magnet of the electromagnetic actuator in the displacement self-sensing device of the electromagnetic actuator, and eddy currents are induced under the high-frequency magnetic field of the coil, so that the high-frequency inductance of the coil is reduced.
Further, the displacement self-sensing device of the electromagnetic actuator is characterized in that the coil inductance value of the electromagnetic actuator and the displacement of the electromagnetic actuator are in a monotonic function relation in a certain range, and the function is determined as the actual displacement of the electromagnetic actuator, so that the displacement measurement of the electromagnetic actuator can be realized through the measurement of the coil inductance.
The principle of the invention is as follows: when the coil of the electromagnetic actuator carries an electric current (DC-100 hz, 0.1-10A), it acts as an electromagnet with north and south poles defined by the ampere right hand rule. An attractive or repulsive magnetic force is generated between the coil and the permanent magnet, thereby generating a movement (displacement change) between the magnet and the coil. Meanwhile, if high-frequency alternating current (0.1-10 MHz,10 mu A) passes through the coil, a high-frequency time-varying magnetic field is generated around the coil. Subsequently, eddy currents are generated in the metal plating of the permanent magnet due to the principle of electromagnetic induction. The inductance (total magnetic energy) of the coil-metal coating as a whole is reduced due to the eddy current effect generating a magnetic field opposite to the permanent magnet. Similar to the eddy current displacement sensor principle, the displacement between the coil and the metal target can be measured by measuring the inductance of the coil at high frequencies. Considering the frequency difference between the drive signal and the inductance measurement signal (for sensing), both signals can be applied to an electromagnetic actuator for simultaneous driving and sensing without interfering with each other.
The present invention is based on this concept and develops a drive circuit with displacement self-sensing to achieve simultaneous displacement sensing and motion control of an electromagnetic actuator. And a miniature flexible electromagnetic actuator was developed and used as an example device for studying and evaluating driving circuits with displacement self-sensing. The micro flexible electromagnetic actuator driven by the circuit realizes a moving range of 200 mu m, and the self-sensing resolution is as high as 0.034 mu m. The strict research reveals the design standard and performance of the sensing-driving integrated circuit, and has good application prospect in widely used electromagnetic actuators and emerging intelligent systems based on flexible electromagnetic actuators. In addition, the driving circuit with displacement self-sensing is also used for a commercial voice coil motor with the linear motion range exceeding 2mm, so that the displacement self-sensing of 0.16 mu m is realized, and the universality of the method is highlighted.
The invention has the following advantages:
compared with the methods for realizing self-perception in the background art, the invention has the advantages that:
1. the invention has the advantages of good universality, simple structure, low cost, no additional hardware, no structure change of the electromagnetic actuator, no need of building a complex mathematical model, no existence of dangerous signals such as high voltage and the like, high safety and synchronous driving and sensing only through a sensing-driving integrated circuit.
2. The invention completely considers the independence and coordination of driving and displacement sensing. Unlike some existing solutions that utilize drive signals to estimate motion/force, the drive circuitry with displacement self-sensing proposed by the present invention can detect the true displacement of the flexible electromagnetic actuator regardless of the influence of body motion.
3. The invention creatively uses two different frequency currents through the coil for driving and sensing without mutual interference.
Drawings
FIG. 1 is a schematic diagram of a sensor-driver integrated circuit;
FIG. 2 (a) is a schematic structural view of a flexible electromagnetic actuator used in the present invention; FIG. 2 (b) is a pictorial view of a flexible electromagnetic actuator used in the present invention;
FIG. 3 (a) is a DC magnetic field coupling between a coil and a permanent magnet; FIG. 3 (b) is a schematic diagram showing the coupling of the coil to the copper foil on the surface of the permanent magnet due to the eddy current effect in an alternating magnetic field (1 MHz);
FIG. 4 (a) shows the inductance and displacement as a function of time for a triangle wave drive (0.1 Hz,67.2 MA); FIG. 4 (b) inductance and displacement linear fit relationship;
FIG. 5 is an inductance measurement noise of the sense-drive integrated circuit when the drive current is zero;
FIG. 6 is a continuous inductance record of the sensor-driver integrated circuit system for different magnitudes of the driving current;
FIG. 7 is a continuous inductance record of the sensor-driver integrated circuit system at different frequency driving currents;
FIG. 8 is a continuous inductance record when the flexible electromagnetic actuator is touched by a feather and tapped by a nylon rod with a sine wave drive current;
fig. 9 is a schematic structural view of a commercial voice coil motor;
FIG. 10 (a) is a graph showing the inductance response and displacement monitoring of a voice coil motor at triangular wave drive current; FIG. 10 (b) shows the inductive displacement relationship and quadratic function fit of a voice coil motor under the sensor-driver integrated circuit system;
the reference numerals are explained as follows:
1: a power amplifier module; 2: an inductance coil; 3: an inductance measurement module; 4: a driving signal; 5: a sensing signal; 6: isolating the inductor; 7: an isolation capacitor; 8: an acrylic plate; 9: a permanent magnet; 10: a stretchable elastic film; 11: a metal copper foil; 12: nylon fixing support; 13: a stator; 14: a mover; 15: a spring; 16: a coil support; 17: a helical coil.
Detailed Description
Embodiments of the drive circuitry with displacement sensing are specifically described below using the flexible electromagnetic actuator and commercial voice coil motor of the present invention as examples.
As shown in fig. 2, the flexible electromagnetic actuator based on the present invention is mainly composed of an acryl fixing plate 8, an inductance coil 2, a permanent magnet 9, a stretchable elastic film 10 and a metal copper foil 11.
First a flexible electromagnetic actuator is made, as shown in fig. 2. The inductor coil 2 is wound by adopting a copper enameled wire with a certain diameter, the inductor coil is fixed on an acrylic plate 8 by using DP460 epoxy resin glue for testing, an organosilicon elastomer is selected for manufacturing the stretchable elastic film 10, then the outer ring of the stretchable elastic film 10 is stuck on the upper surface of the inductor coil 2 by using silica gel glue, and then the permanent magnet 9 is stuck in the center of the stretchable elastic film 10.
It is well known that non-ferromagnetic, highly conductive sensing targets (copper, aluminum, etc.) are ideal choices for achieving high sensing resolution in eddy current displacement sensors. Rubidium-iron-boron magnet (Nd-Fe-B) has poor conductivity (1.43×107S/m), low relative permeability (μr=1.05), and very weak eddy current coupling with the coil. Commercial rubidium-iron-boron magnets typically have a thin nickel-copper-nickel coating on the surface to prevent corrosion. Such coatings are too thin and generally result in high energy dissipation due to their high magnetic permeability and poor electrical conductivity. Therefore, in the design of the flexible electromagnetic actuator, the bottom and side surfaces of the permanent magnet 9 are covered with a thin layer of copper foil to improve the displacement sensing resolution. Since strong eddy current induced ac magnetic field coupling exists between the coil and the copper foil, no ac magnetic field exists inside the permanent magnet and on the copper foil layer thereof, as shown in fig. 3 (b). The copper foil is not only used as a sensing target of displacement sensing, but also used as a shielding layer of a high-frequency alternating current magnetic field. Whereas for a slowly varying static magnetic field generated by a drive signal (DC-100 Hz) exciting coil, the magnetic force is generated to the magnet by directly passing through the copper foil, as shown in fig. 3 (a), pushing/pulling the magnet to move up/down, further confirming the self-perception of the mutual noninterference of the drive and displacement.
The displacement sensing based on low-frequency driving and high-frequency inductance measurement obtained through the simulation can work independently in principle. Thus, an integrated drive circuit with displacement self-sensing is proposed for simultaneous driving and displacement sensing, the schematic diagram of which is shown in fig. 1. The circuit comprises two parts, namely a measuring unit and a driving unit. The measuring unit consists of an inductance measuring module 3 and an isolation capacitor 7. The driving unit mainly comprises a power amplifier module 1 and an isolation inductor 6, wherein the input of a circuit is a driving signal 4, the output of the circuit is a sensing signal 5, an inductance coil 2 is connected between the isolation inductor 6 and an isolation capacitor 7, and a permanent magnet 9 is positioned above the inductance coil 2.
It is noted that the inductance measuring module 3 adopts an LDC1614 measuring module, in order to prevent large driving current (DC-100 Hz) from passing through the inductance measuring module 3, an isolation capacitor 7 is added between the measuring module and one terminal of the coil, and the isolation function of two frequency current signals is achieved. Therefore, the value of the isolation capacitor 7 is required to be enough large under the low-frequency signal, so that the isolation capacitor can be regarded as an open circuit of the low-frequency current of the driving unit, and plays an isolating role on the low-frequency excitation signal; the impedance is extremely small at high frequency, and can be regarded as short circuit of a measurement signal, and the measurement of the inductance value of the coil is not affected. For the other hand, in order to keep the two ends of the coil ungrounded and to avoid high frequency oscillating currents (10-100 mua) passing through the drive unit, two isolation inductors 6 are connected in series on the two legs of the connection wire terminal and the drive current. The inductors at the two ends show larger impedance under the high-frequency measurement current, so that the interference of the high-frequency current on the power amplifier module is avoided, and the direct grounding at the two ends of the coil is also avoided. And shows a small impedance at low frequency drive current, while consuming a portion of the power of the fixed drive current for the coil, without altering the function of the actuator drive control, which is negligible. In summary, in the integrated circuit of sensing and driving, sensing measurement and driving can be performed simultaneously without interference.
One embodiment of the present invention characterizes the function of the present invention with a flexible electromagnetic actuator and evaluates its self-sensing performance. First, a drive current (triangle waveform) of 0.1hz,67.2ma was applied to a flexible electromagnetic actuator test sample. As shown in fig. 4 (a), the inductance measured by the drive circuitry with displacement from sensing varies in synchronism with the actual displacement monitored by the laser sensor. The result shows that the inductance increases linearly with displacement, as shown in fig. 4 (b), the displacement sensing sensitivity of the driving circuit with displacement self-sensing is 4.0nH/μm, and the fitting equation is shown in fig. 4 (b). An inductance measurement noise record (drive current zero) of 500s is plotted in fig. 5, indicating a standard deviation noise (RMS) of 0.14nH. Thus, the sensing resolution of the drive circuit with displacement from sensing is as high as 0.034 μm (RMS). In addition, in order to evaluate the sensing performance of the sensing-driving integrated circuit system in practical application, driving current experiments with different amplitudes and frequencies are performed. First, a 0.5Hz sine wave was used, with current amplitudes from 33.6mA to 134.4mA to drive the flexible electromagnetic actuator, and as shown in FIG. 6, the measured inductance changes corresponded to vibrations of 48.2 μm, 94.0 μm, 137 μm and 179 μm, respectively. At these four drive voltages, the inductance change (peak-to-peak) increase indicates constant sensitivity to dynamic displacement measurements of different magnitudes. Then, the flexible electromagnetic actuator was driven by applying a current (fixed amplitude 87.3mA, sine wave) with a frequency from 0.1Hz to 2Hz, and the result is shown in fig. 7, which shows that the driving characteristics and measurement sensitivity of the integrated sensor-driver circuitry remain unchanged when driving the current at different frequencies.
Furthermore, we have investigated the ability of the circuitry to detect displacements caused by external stimuli or disturbances in the case of sine wave drive signals, as shown in fig. 8. A 0.5Hz sine wave drive current (87.3 mA) was first applied to the flexible electromagnetic actuator test sample with a drive circuit with displacement self-sensing. The measured inductance change shows that the system can clearly detect 127 mu m vibration, and has good repeatability and stability. Then, the magnet was knocked with a hexagonal nylon column, and the inductance value clearly showed the downward displacement of the magnet (10 s-15s in the figure). Soft touch of feathers (22 s-27s in the figure) can also be observed from the sinusoidal inductance curve. Unlike some existing solutions that utilize drive signals to estimate motion/force, the present invention proposes a sensor-driver integrated circuit system that can detect the true displacement of a flexible electromagnetic actuator, regardless of the effect of motion. This highlights the potential for using flexible electromagnetic actuators with drive circuitry with displacement self-perception for haptic and interactive human-machine interfaces.
One embodiment of the present invention is applied to simultaneously driving and sensing a voice coil motor. The voice coil motor used is an improvement on the basis of the traditional commercial voice coil motor, and the sensing resolution is improved by covering copper foil (the same design as the flexible electromagnetic actuator) in the permanent magnet. As shown in fig. 9, the voice coil motor is composed of a 3D printed nylon fixing bracket 12, a stator 13, i.e., a permanent magnet portion, a mover 14, i.e., an inductance coil, and a spring 15. The mover is composed of a 3D printing coil support 16 and a spiral coil 17 wound on the support, as shown in an enlarged view of fig. 9. To provide a restoring force, a spring 15 connects the upper surface of the mover 14 and the nylon fixing bracket 12. The length of the spring 15 is selected so that the mover 14 is suspended at the midpoint of the range of motion of the voice coil motor, and the spring rate is selected to match the range of motion.
According to an embodiment of the present invention, when the voice coil motor is driven with a triangle wave of 0.1Hz (79.4 mA), the displacement (data monitored using the laser sensor) curve is well matched with the inductance measurement curve, and the moving range is 2mm, as shown in fig. 10 (a). However, it should be noted that the inductance curve is not perfectly triangular like the displacement curve due to the non-linearity of the sensing characteristic near the low point of the range of motion. As shown in fig. 10 (b), the driving circuit system with displacement self-sensing has nonlinear response between inductance and displacement, and the second-order polynomial equation is selected to fit the L-d curve well, so that the driving circuit with displacement self-sensing provided by the invention has good compatibility with the traditional voice coil motor, and realizes a larger motion range of 2mm and self-sensing resolution of 0.16 μm.
The invention can be applied to a core mechanical system of a large-scale precise device, and needs a displacement sensor to perform real-time measurement positioning and local feedback control so as to meet the control requirement of micro-scale or nano-scale, such as a self-adaptive mirror system based on voice coil motor driving. The voice coil motor adaptive optics system typically attaches a permanent magnet to the back of the deformable mirror and then interacts with a voice coil motor mounted on a base to drive the adaptive mirror into deformation. The non-contact structure enables the deformation of the self-adaptive mirror to be large, the driving requirements of the self-adaptive mirror on large stroke and high bandwidth can be well met, and meanwhile, the linearity of the voice coil motor driver is high and almost no hysteresis phenomenon exists in the piezoelectric actuator. In the voice coil motor self-adaptive mirror surface shape control process, a non-contact local feedback loop is formed by measuring the deformation of the self-adaptive mirror by using a displacement sensor and a voice coil motor driver, so that a self-adaptive mirror surface shape control loop is established, the surface shape of the self-adaptive deformable mirror is adjusted in real time, the response speed of a system is effectively improved, the tracking error of the system is reduced, and higher control precision is obtained. By combining the technical implementation scheme of the invention, the voice coil motor driver can synchronously sense displacement in the driving process, so that a small enough volume is realized, enough measuring units can be arranged in a limited space, and the required measuring precision can be achieved based on a measuring probe with a small size.
The invention mainly provides a basic principle and an implementation method of a circuit system which are based on the combination of an electromagnetic driving principle and an eddy current sensing principle and can synchronously drive and sense displacement information of an electromagnetic actuator. The actual application system can be correspondingly adjusted and supplemented according to the application occasion, so that the requirements are better met. The above description is only a simpler, more effective embodiment of the invention. Conventional electromagnetic actuator-based systems in wide use today can achieve closed-loop control by the present invention without the addition of external sensors or encoders. The flexible electromagnetic actuator and the driving circuit system with displacement self-perception are utilized, any additional hardware is not required to be integrated into the electromagnetic actuator, the characteristics of multifunction, high performance and easiness in realization of the sensing-driving integrated circuit system are highlighted, the sensing capability of the novel flexible electromagnetic actuator is supported, and a plurality of possibilities are opened up for the application of the novel flexible electromagnetic actuator in the fields of touch sense, VR/AR, human-computer interface and the like.
The invention, in part, is not disclosed in detail and is well known in the art.
While the foregoing describes illustrative embodiments of the present invention to facilitate an understanding of the present invention by those skilled in the art, it should be understood that the present invention is not limited to the scope of the embodiments, but is to be construed as protected by the accompanying claims insofar as various changes are within the spirit and scope of the present invention as defined and defined by the appended claims.
Claims (6)
1. A displacement self-sensing device for an electromagnetic actuator, the device comprising: a flexible electromagnetic actuator and a circuit portion including a drive unit and an inductance measurement unit; the flexible electromagnetic actuator consists of an acrylic fixed plate, an inductance coil, a permanent magnet, a stretchable elastic film and a metal copper foil; the inductance measuring unit consists of a measuring module and an isolation capacitor; the driving unit consists of a power amplifier module and an isolation inductor;
the driving unit and the measuring unit work independently and are not mutually influenced; the power amplification module can amplify the driving signal to generate a high-current excitation signal to drive the electromagnetic actuator to move, and the inductance measurement module can measure the inductance of the coil of the electromagnetic actuator under high frequency and output displacement information corresponding to the inductance;
the isolation capacitor shows extremely large impedance under the low-frequency excitation signal, prevents the low-frequency excitation signal from flowing into the inductance measurement module to interfere the high-frequency signal measurement inductance, plays an isolation role, and enables the low-frequency excitation signal to flow through the coil and then return to the power amplification module to form a current closed loop of the driving unit; the isolation capacitor has extremely small impedance under high-frequency measurement signals, so that the influence of the isolation capacitor on inductance measurement in a measurement unit loop can be ignored;
the isolation inductor shows extremely large impedance under the high-frequency inductance measurement signal, prevents the high-frequency measurement signal from flowing into the driving unit to interfere the motion of the electromagnetic actuator, plays an isolation role, and enables the high-frequency measurement signal to flow through the coil and then return to the inductance measurement module to form a current closed loop of the measurement unit; the isolation inductor has extremely small impedance in a low-frequency excitation signal, and consumes a part of power of fixed driving current in a driving unit loop, but does not change the function of driving control of an actuator;
the independent work of the inductance measuring unit loop and the driving unit loop is realized by the aid of the isolation inductance and the isolation capacitance, and the driving synchronous displacement self-sensing of the electromagnetic actuator is realized by the aid of the sensing-driving integrated circuit.
2. The device of claim 1, wherein the flexible electromagnetic actuator is constructed by winding a copper-clad wire with a certain diameter into an inductance coil, fixing the inductance coil on an acrylic plate by using DP460 epoxy resin glue, manufacturing a stretchable circular elastic film by using an organosilicon elastomer, then adhering an outer ring of the circular elastic film on the upper surface of the inductance coil by using silica gel glue, and adhering a permanent magnet on the center of the elastic film.
3. The apparatus of claim 2, wherein the bottom and sides of the permanent magnet are covered by a thin layer of copper foil.
4. The apparatus of claim 1, wherein the driving portion comprises a power amplifier module and two isolation inductors.
5. The apparatus of claim 1, wherein the permanent magnet of the electromagnetic actuator has a metal coating on a surface thereof to induce eddy currents in a high frequency magnetic field of the coil, thereby reducing the high frequency inductance of the coil.
6. The apparatus of claim 1, wherein the coil inductance value of the electromagnetic actuator is monotonically related to displacement over a range, the function being determined as an actual displacement of the electromagnetic actuator for measuring the electromagnetic actuator displacement by the coil inductance.
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| CN117705335A (en) * | 2024-02-05 | 2024-03-15 | 中国科学技术大学 | Inductance type reconfigurable multidimensional force sensor |
| CN117705335B (en) * | 2024-02-05 | 2024-05-14 | 中国科学技术大学 | Inductance type reconfigurable multidimensional force sensor |
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