A multi-directional non-contact electromagnetic actuator and its control method and system

Abstract

The present invention discloses a multi-directional non-contact electromagnetic actuator, its control method and system, which are integrated into an airbag shock absorber and belong to the technical field of active control of ship structure vibration. By evenly distributing and integrating three single-direction electromagnetic actuator units inside the airbag shock absorber, the present invention realizes the output of force / torque in one translational direction and two rotational directions. This multi-directional actuator has a high integration degree and a large output force. According to the positional relationship of the three actuator units, the present invention controls the magnitude and phase of the coil currents of the three actuator units respectively, so that the actuator generates a controllable translational force and rotational torque externally to cancel the force and torque transmitted through the shock absorber in the vibration isolation device of mechanical equipment, thereby suppressing the transmission of multi-directional vibration.

Description

Technical Field

[0001] The present invention belongs to the technical field of active control of ship structure vibration, and more specifically, relates to a multi-directional non-contact electromagnetic actuator, and a control method and system thereof. Background Art

[0002] Vibrations generated by the operation of power machinery and equipment have many adverse effects on ships. It not only makes the living and working environment of crew members poor, but also makes the hull structure and equipment, etc. be subjected to alternating loads for a long time, which is prone to fatigue damage, and at the same time affects the operation of many precision instruments. For warships, more importantly, mechanical vibration increases its underwater radiated noise, seriously affecting its underwater stealth performance. At present, the most important means of vibration reduction and noise reduction on ships are passive vibration isolation devices such as airbags and rubber. These devices can reduce the total vibration level in the whole frequency band, but they are not flexible to use and it is very difficult to eliminate low-frequency line spectrum vibration. Active vibration isolation technology can effectively control low-frequency line spectrum vibration. After decades of development, a large number of achievements have been made in the field of active vibration isolation technology at home and abroad, and various types of active and passive vibration isolators have also been applied to ships. However, in ship vibration isolation devices, the vibration sources are complex and multi-directional, and the vibration isolators have a certain volume, and the installation surface with the hull base cannot be regarded as a point. Therefore, the force transmitted to the hull base through a single vibration isolator in the vibration isolation device not only includes translational force, but also has a certain force couple component. Generally speaking, there are three main reasons for the multi-directionality of the vibration transmitted to the base: one is that there are excitation forces in multiple directions when the vibration source equipment is working normally. The second is that due to the uneven load of the vibration source on the vibration isolation device, even if the vibration source has a single-direction excitation force, the transmitted force to other structures will be multi-directional due to coupling. The third is that the non-point contact of the vibration isolator results in the force acting on the connecting structure being an uneven surface force (moment), rather than an ideal single force. At present, the single-direction vibration active control actuators provided are difficult to meet the increasingly high vibration suppression requirements.

[0003] Active vibration isolation has the characteristics of high vibration isolation efficiency and good control effect on line spectrum vibration compared with passive vibration isolation. Its core equipment is the actuator, which is the execution mechanism of the system. The performance of the actuator determines the best vibration reduction and isolation effect that the system can achieve. At present, most of the existing multi-directional or multi-degree-of-freedom active vibration isolation devices use vibration dampers (with internal integration or unidirectional actuators nearby) distributed at different positions of the entire vibration isolation device to achieve multi-directional active control of the vibration of the device. For the actuators in each of its single vibration dampers, they all have only unidirectional active control capabilities. Therefore, it is also limited to be mostly applied to isolate vibrations with frequencies of 1 Hz or even lower, such as optical instruments and lithography machines, and it is difficult to be applied to multi-directional vibration isolation application fields such as ships that need to consider the elastic vibration characteristics of equipment and bases.

[0004] Patent CN2018103537204 discloses a multi - degree - of - freedom active vibration isolation device and method. An air spring and a pneumatic proportional valve are used as an active actuator in the device. The characteristics of this actuator determine that its vibration isolation effect is poor in the vibration range of 10Hz to 200Hz, which is of concern to ships, and the volume of the vibration isolation device is relatively large.

[0005] Patents CN2018103008997 and CN2017114224410 are both based on the Stewart platform. They use six electromagnetic negative - stiffness vibration isolators or voice - coil actuators and flexible hinges respectively to achieve vibration control of three translational degrees of freedom and three rotational degrees of freedom. They also have the disadvantages of relatively large volume, and the contact - type actuators will also reduce the vibration isolation effect of passive vibration isolators.

[0006] Patent CN2015203201657 discloses an impact - resistant main - passive hybrid vibration isolator. An air - bag vibration isolator is used to bear the weight of the equipment and isolate the broadband vibration of the equipment, and an electromagnetic actuator is used to isolate the line - spectrum vibration of the equipment. It has the advantage of excellent vibration isolation performance, but it can only perform vibration control in the direction consistent with the installation direction and cannot meet the multi - directional vibration control requirements of ships.

[0007] US5887858A discloses a main - passive support structure, in which several actuators are also integrated in the air spring, aiming to increase the unidirectional driving force. And in this patent, the requirement and control method for multi - directional control are not proposed, so the layout method is not given for actuator integration, and it is not a multi - directional actuator design. Summary of the Invention

[0008] Aiming at the defects of the prior art, the purpose of the present invention is to provide a multi - directional non - contact electromagnetic actuator and its control method and system, aiming to solve the problems that the output force of the existing actuator is not large enough and multi - directional vibration control cannot be carried out simultaneously.

[0009] To achieve the above purpose, in the first aspect, the present invention provides a multi - directional non - contact electromagnetic actuator, which is integrated into an air - bag shock absorber and includes: three structurally identical electromagnetic actuator units and an air - bag;

[0010] The three electromagnetic actuator units are uniformly distributed and integrated on the upper and lower covers of the air - bag shock absorber with the air - bag center line as the axis, and are separated from each other to achieve the torque output in one translational direction and two rotational directions.

[0011] Preferably, the three electromagnetic actuator units are mutually at an angle of 120°.

[0012] Preferably, the distance between the edges of each electromagnetic actuator unit is not less than 3mm.

[0013] Preferably, the electromagnetic actuator unit includes: a first component and a second component;

[0014] The first component and the second component are separated from each other;

[0015] The first component includes: an iron core, a coil, a permanent magnet, a coil bobbin, and a magnetic rubber;

[0016] The iron core is formed by laminating a plurality of "mountain"-shaped silicon steel sheets of different sizes, and the top view of the laminated structure is nearly circular; the coil bobbin is sleeved on the middle cylinder of the iron core; the coil is wound on the coil bobbin in the same direction; the permanent magnet covers the upper end face of the iron core; the magnetic rubber is adhered to the upper end face of the permanent magnet;

[0017] The second component is composed of an armature and a support rod; the lower end face of the armature faces the upper end face of the magnetic rubber and is fixed to an external device through a steel structure support rod.

[0018] Preferably, the gap between the first component and the second component is 2 mm to 5 mm.

[0019] To achieve the above object, in a second aspect, the present invention provides a control method for a multi-directional non-contact electromagnetic actuator as described in the first aspect. By separately controlling the magnitude and phase of the coil currents of the three electromagnetic actuator units, a controllable translational force and a rotational torque are generated by the multi-directional electromagnetic actuator to cancel the forces and torques transmitted through the shock absorber in the vibration isolation device of the mechanical equipment, thereby suppressing the transmission of multi-directional vibrations.

[0020] Preferably, for any desired output force (F, M x , M y ), it can be decomposed into the translational output forces of the three electromagnetic actuator units respectively and uniquely, that is

[0021]

[0022] wherein, F1, F2, and F3 respectively represent the output forces of the three actuator units, F represents the translational output force of the multi-directional actuator, M x , M y respectively represent the output torques in the x-direction and y-direction of the multi-directional actuator, and L represents the distance from the center of the actuator unit to the center of the multi-directional electromagnetic actuator.

[0023] Preferably, the active control of multi-directional vibrations is achieved as follows:

[0024] (1) According to the detected vibrations transmitted to the base, the vibrations to be cancelled are decomposed into rotational components around two horizontal axes and a translational component along another axis that are orthogonal to each other;

[0025] (2) For each rotational component and translational component, calculate the control currents required for the three electromagnetic actuator units respectively, so that the multi-directional output force of the multi-directional electromagnetic actuator matches the multi-directional transfer force to the base, in order to cancel out the multi-directional vibrations transmitted to the base.

[0026] Preferably, the input current of each electromagnetic actuator unit is the sum of the input currents calculated for the two rotational components and translational components respectively.

[0027] To achieve the above object, in a third aspect, the present invention provides a control system for a multi-directional non-contact electromagnetic actuator, including: a processor and a memory;

[0028] The memory is used to store computer programs or instructions;

[0029] The processor is used to execute the computer programs or instructions in the memory, so that the method described in the third aspect is executed.

[0030] Generally speaking, compared with the prior art through the above technical solutions conceived by the present invention, the following beneficial effects are obtained:

[0031] (1) The present invention provides a multi-directional non-contact electromagnetic actuator, which is integrated into an airbag shock absorber. By evenly distributing and integrating three single-direction electromagnetic actuator units inside the airbag shock absorber, the output of torque in one translational direction and two rotational directions is realized. This multi-directional actuator has a high integration degree and a large output force, can effectively attenuate the multi-directional line spectrum vibrations transmitted to the base through the shock absorber, improve the effect of suppressing line spectrum vibrations, and lay a foundation for the next step of realizing multi-directional line spectrum vibration control. And it can be used upside down according to the specific use scenario without affecting the performance. It can not only be integrated with airbag shock absorbers, but also be combined with rubber shock absorbers, wire rope shock absorbers, etc.

[0032] (2) The present invention provides a control method and system for a multi-directional non-contact electromagnetic actuator. Due to the relative positional relationship of the three actuator units, by respectively controlling the magnitude and phase of the coil currents of the three actuator units, the multi-directional non-contact electromagnetic actuator generates an external translational force and a rotational torque. With appropriate control, the transmission of force and torque of mechanical equipment can be cancelled, and thus the transmission of multi-directional vibrations can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is the front view of the multi-directional non-contact electromagnetic actuator integrated inside the airbag shock absorber provided by the present invention.

[0034] Figure 2 is the top view of the multi-directional non-contact electromagnetic actuator integrated inside the airbag shock absorber provided by the present invention.

[0035] Figure 3It is a cross-sectional view of a single actuator unit provided by the present invention.

[0036] Figure 4 It is a left view of a single actuator unit provided by the present invention.

[0037] Figure 5 It is a top view of a single actuator unit provided by the present invention.

[0038] Figure 6 It is a cloud map of the magnetic flux density distribution after the integration of the actuators provided by the present invention.

[0039] Figure 7 It is a schematic diagram of the output force test result provided by the present invention.

[0040] In all the drawings, the same reference numerals are used to represent the same elements or structures, where:

[0041] 1 - upper cover plate; 2 - lower cover plate; 3 - bladder; 4 - electromagnetic actuator unit; 5 - support structure; 6 - air charging and discharging hole; 7 - electrical connector; 8 - iron core; 9 - coil; 10 - permanent magnet; 11 - coil bobbin; 12 - magneto-rubber; 13 - armature; 14 - enameled wire; 15 - temperature sensor; 16 - screw. Specific embodiments

[0042] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0043] Figure 1 and Figure 2 are respectively the front view and the top view of the multi-directional non-contact electromagnetic actuator integrated inside the airbag shock absorber provided by the present invention. As Figure 1 and Figure 2 shown, its structure includes: an airbag, three electromagnetic actuator units 4, a support structure 5 and related cables, for example, two types of cables, namely coil wire and temperature sensor cable.

[0044] The airbag used is a marine bag-type airbag with a load capacity of 1.5 tons, including: an upper cover plate 1, a lower cover plate 2 and a bladder 3. An airbag air charging and discharging hole 6 is provided on the upper cover plate 1. The lower cover plate 2 is connected to external equipment through an electrical connector 7, which is respectively used to drive the actuator to work and monitor the temperature inside the coil.

[0045] The actuator includes: three actuator units 4 with the same structure. In this embodiment, a 25N actuator unit (100Hz, 6A current) is adopted. Figure 3 , Figure 4 and Figure 5 are respectively the cross-sectional view, the left view and the top view of a single actuator unit provided by the present invention. AsFigures 3 to 5 As shown in the figure, the actuator unit 4 is composed of an iron core 8, a coil 9, a coil bobbin 11, a permanent magnet 10, a magnetic rubber 12 and an armature 13. The iron core 8 is laminated by a plurality of "mountain"-shaped silicon steel sheets of different sizes coated with an insulating layer, which can effectively reduce the eddy current loss. The top view of the formed iron core structure is nearly circular, and the side view is "mountain"-shaped. It is fixed to the airbag lower cover plate 2 by four screws 16. The coil 9 is wound by an enameled wire 14, which can withstand a high temperature of 200°. The enameled wire 14 is wound clockwise on the coil bobbin 11. The coil bobbin 11 is sleeved on the middle cylinder of the iron core 8, and a PT-100 type temperature sensor 15 is fixed inside the coil. The neodymium iron boron permanent magnet 10 covers the upper end face of the iron core 8, and the magnetic rubber 12 is adhered to the upper end face of the permanent magnet 10 by an adhesive, which can enhance the air gap magnetic permeability and resist a certain degree of impact. There is a gap of about 2 mm between the magnetic rubber and the armature. The armature is riveted by silicon steel sheets and is fixed to the other cover plate of the airbag by four screws 13 through a support structure 5. Each actuator unit has two types of cables, namely a coil wire and a temperature sensor cable, which are connected to external devices through an airtight electrical connector 7 on the airbag lower cover plate, and are respectively used to drive the actuator to work and monitor the temperature inside the coil to prevent the temperature from being too high. There are cable holes and ventilation holes on the cover plate, and the external interface is connected to the airbag through an airtight seal.

[0046] The armature support rod is a rigid structure, which is convenient for transmitting the output force of the actuator. Each actuator unit has two types of cables, namely a coil wire and a temperature sensor cable, which are respectively used to drive the actuator to work and monitor the temperature inside the coil to prevent the temperature from being too high.

[0047] Three actuator units 4 are installed on the upper and lower cover plates of the airbag shock absorber with the airbag center line as the axis and an included angle of 120° with each other, and they are separated from each other. To reduce magnetic field interference, the distance between the edges of each actuator unit is not less than 3 mm.

[0048] Working principle: When an alternating current is passed through the coil of the actuator unit, an alternating electromagnetic field will be formed in the gap between the magnetic rubber and the armature. The alternating electromagnetic field generates an alternating force on the armature, and its force satisfies the following formula:

[0049]

[0050] Among them, μ0 is the magnetic permeability, i is the excitation current, B0 is the static magnetic field generated by the permanent magnet in the actuator, and the purpose is to improve the linearity of the actuator output force. S is the cross-sectional area of the upper end face of the iron core, N is the number of turns of the coil, and Z0 is the equivalent gap between the two parts of the actuator. The above parameters are all constants after the actuator design is completed. It can be seen that the output force of the actuator is proportional to the cross-sectional area S and inversely proportional to the equivalent gap Z0.

[0051] By controlling the magnitude and phase of the current in the actuator coil, the actuator generates a corresponding output force.​

[0052] Due to the relative positional relationship of the three actuator units, by respectively controlling the magnitude and phase of the coil currents of the three actuator units, the multi-directional non-contact electromagnetic actuator generates a translational force and a rotational torque externally. With an appropriate additional control system, the transmission of force and torque of mechanical equipment can be offset, thereby suppressing the transmission of multi-directional vibration. The specific principle and method are as follows:

[0053] Figure 6 It is the cloud map of the magnetic flux density distribution after the integration of the actuator provided by the present invention. Establish a coordinate system as shown in Figure 6 and number the three actuator units in the clockwise direction respectively. Assume that the output forces of each actuator unit are F i (i = 1, 2, 3), and the distance of each actuator unit from the center of the mounting base plate of the multi-directional actuator (the origin of the coordinate system) is L. From the geometric relationship, it can be known that the force arms of the three actuator units with respect to the x-axis and y-axis satisfy a right triangle relationship. Let the vertical translational force and torques output by the multi-directional actuator be Fz and Mx, My respectively, then the following relationships are satisfied among them:

[0054]

[0055] In this way, the unique solution of the system of equations that meets the conditions can be obtained.

[0056] It can be seen from this that the excitation current of each actuator unit affects the output characteristics of the entire actuator. The output of the multi-directional actuator corresponds uniquely to the output of each actuator unit.

[0057] ① When the multi-directional actuator only needs to output a vertical force F, it is necessary to satisfy:

[0058]

[0059] After solving, it can be obtained that

[0060]

[0061] ② When the multi-directional actuator only needs to output a torque M x , it is necessary to satisfy:

[0062]

[0063] After solving, it can be obtained that

[0064]

[0065] ③ When the multi-directional actuator only needs to output a torque M y , it is necessary to satisfy:

[0066]

[0067] After solving, we can obtain

[0068]

[0069] From the above three equations, it can be seen that for any desired output forces (F, Mx, My), they can be decomposed into the translational output forces of the three actuator units respectively, that is

[0070]

[0071] Conversely, according to the above formula, by controlling the output forces of the three actuator units respectively, the external manifestation can be a controllable output of a vertical force and two rotational torques. Coupled with the peripheral control system, the active control of multi-directional vibration can be achieved. Specifically

[0072] When the vibration transmitted to the base is vertical (z-direction), control currents with the same amplitude and phase can be input to the three actuator units, so that the three actuators output the same force, and the control resultant force is the sum of the output forces of the three actuators to cancel the vibration transmitted to the base. The control resultant force is the same in magnitude and opposite in phase to the vibration force to be cancelled

[0073] When the vibration transmitted to the base is rotational, the rotational motion to be cancelled is first decomposed into rotational components that are orthogonal to each other and around two horizontal axes. For each rotational component, control currents with different amplitudes and phases are input to the three actuator units respectively, so that the control resultant force of the three actuators is zero, and only the control resultant torque is used to cancel the rotational vibration transmitted to the base. The control resultant torque is the same in magnitude and opposite in phase to the rotational component of the torque to be cancelled. The same treatment is carried out for the other rotational component. Since the two rotational components are orthogonal, the input current of each actuator unit is the sum of the input currents calculated for the two rotational components

[0074] The magnetic field distribution in the plane of the actuator air gap when the multi-directional actuator inputs an excitation current of 6A is as Figure 6 shown. The magnetic field is concentrated inside the actuator unit, and the influence between the actuator units is small

[0075] Figure 7 is a schematic diagram of the output force test results provided by the present invention. Among them, (a), (b), and (c) are the relationships between the amplitudes of the output vertical force, torque Mx, and torque My and the excitation current and frequency respectively. As Figure 7 shown, the vertical force can reach up to about 170N at most, Mx can reach up to about 7000N·mm at most, and My can reach up to about 12000N·mm at most

[0076] Those skilled in the art can easily understand that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A multi-directional non-contact electromagnetic actuator integrated in an airbag shock absorber, characterized in that Comprising: Three electromagnetic actuator units with the same structure and an airbag, where the electromagnetic actuator units are used to provide translational output force; The three electromagnetic actuator units are uniformly distributed and integrated on the upper and lower covers of the airbag shock absorber with the center line of the airbag as the axis, and are separated from each other to achieve the output of vertical translational force, rotational torque in the x-axis direction, and rotational torque in the y-axis direction.

2. The multi-direction non-contact electromagnetic actuator according to claim 1, wherein The three electromagnetic actuator units are at an angle of 120° to each other.

3. The multi-directional non-contact electromagnetic actuator according to claim 2, wherein The edge distance of each electromagnetic actuator unit is not less than 3 mm.

4. The multi-directional non-contact electromagnetic actuator according to claim 1, characterized in that The electromagnetic actuator unit includes: a first component and a second component; The first component and the second component are separated from each other; The first component includes: an iron core, a coil, a permanent magnet, a coil bobbin, and a magnetic conductive rubber; The iron core is formed by laminating a plurality of "mountain”-shaped silicon steel sheets of different sizes, and the top view of the laminated structure is nearly circular; the coil bobbin is sleeved on the middle cylinder of the iron core; the coil is wound on the coil bobbin in the same direction; the permanent magnet covers the upper end face of the iron core; the magnetic conductive rubber is adhered to the upper end face of the permanent magnet; The second component consists of an armature and a support rod; the lower end face of the armature is opposite to the upper end face of the magnetic conductive rubber, and is fixed to an external device through a steel structure support rod.

5. The multi-direction non-contact electromagnetic actuator according to claim 4, characterized in that, The gap between the first component and the second component is 2 mm to 5 mm.

6. A control method for a multi-directional non-contact electromagnetic actuator according to any one of claims 1 to 5, characterized in that By separately controlling the magnitude and phase of the coil currents of the three electromagnetic actuator units, a controllable translational force and rotational torque are generated by the multi-directional electromagnetic actuator to cancel the force and torque transmitted through the shock absorber in the vibration isolation device of mechanical equipment, thereby suppressing the transmission of multi-directional vibration.

7. The method according to claim 6, characterized in that For any desired output forces (F, M x , M y ), they can be decomposed into the translational output forces of the three electromagnetic actuator units respectively and uniquely, that is Among them, F1, F2, and F3 respectively represent the output forces of the three actuator units, F represents the translational output force of the multi-directional actuator, M x , M y respectively represent the output torques of the multi-directional actuator in the x-direction and y-direction, and L represents the distance from the center of the actuator unit to the center of the multi-directional electromagnetic actuator.

8. The method according to claim 6, characterized in that, The active control of multi-directional vibration is realized as follows: (1) According to the detected vibration transmitted to the base, the vibration to be cancelled is decomposed into rotational components around two horizontal axes and a translational component along another axis that are orthogonal to each other; (2) For each rotational component and translational component, the control currents required for the three electromagnetic actuator units are calculated respectively, so that the multi-directional output force of the multi-directional electromagnetic actuator matches the multi-directional transmission force to the base, to cancel the multi-directional vibration transmitted to the base.

9. The method according to claim 8, wherein The input current of each electromagnetic actuator unit is the sum of the input currents calculated for the two rotational components and the translational component respectively.

10. A control system for a multi-direction non-contact electromagnetic actuator, characterized in that, Comprising: A processor and a memory; The memory is used to store computer programs or instructions; The processor is used to execute the computer programs or instructions in the memory, so that the method according to any one of claims 6 to 9 is executed.

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