Small angle generation system and method based on magnetorheological fluid and fine adjustment motor

Abstract

The invention relates to the technical field of precise instruments and control, in particular to a small angle generation system and method based on magnetorheological fluid and a fine adjustment motor. The device comprises two capacitance angular displacement sensors which are used for measuring the relative rotation angle between an inner shaft and an outer shaft; the angle sensor signal acquisition module is used for acquiring relative rotation angles measured by the two capacitance angular displacement sensors, subtracting the two relative rotation angles and transmitting an angle difference value to the feedback controller; the feedback controller is used for comparing the angle difference value with a preset target angle and calculating an angle error, and the signal processing and analyzing unit is used for analyzing and processing the angle error through a closed-loop control strategy so as to control the motor driving control unit and the magnetic field control unit according to the angle error. And the relative rotation angle between the inner shaft and the outer shaft is stabilized within the target angle. The characteristics of motor micro-step subdivision driving and magnetorheological fluid damping vibration suppression are combined, and high-accuracy micro angle generation is achieved.

Description

Technical Field

[0001] This invention relates to the field of precision instruments and control technology, and more specifically, to a small-angle generation system and method based on magnetorheological fluid and fine-tuning motor. Background Technology

[0002] Currently, small angle adjustments (such as machining and precision instrument calibration) mostly rely on purely mechanical structures (such as worm gears and lead screw drives), which have problems such as insufficient accuracy, slow response speed, and complex structure. Magnetorheological fluid, as a smart material, can have its rheological properties quickly adjusted by an external magnetic field (millisecond-level response), and has been widely used in sensors, damping control, power transmission and other fields. Although magnetorheological fluid technology has made progress, the following problems still exist in the field of small angle generation and control: (1) Insufficient active control capability: Existing technologies are mostly used for passive detection or power transmission (such as sensors and flexible motors), lacking the ability to actively generate and maintain small angles; (2) Limited linearity and accuracy: The relationship between the viscosity and magnetic field of magnetorheological fluid is easily affected by factors such as temperature and particle sedimentation, resulting in poor linearity and repeatability of angle adjustment; (3) Structural complexity and cost: Some systems need to be combined with capacitance detection, multi-stage transmission or complex control circuits (such as servo motors and frequency converters), resulting in large size and high cost.

[0003] In the prior art, patent CN201120144392 proposes a tilt sensor based on magnetorheological fluid, which detects angles through capacitance changes, but it is only used for passive measurement and cannot actively generate angles. Patent CN201420326129 describes a magnetorheological flexible motor that achieves flexible power output, but its core is overload protection and does not involve precise control of small angles. Patent CN201310712684's continuously variable transmission system relies on complex control circuits and is difficult to directly transfer to small-angle scenarios. Therefore, there is a need to provide a small-angle generation system and method based on magnetorheological fluid and a fine-tuning motor. Summary of the Invention

[0004] This invention aims to at least partially solve one of the technical problems in related technologies. Therefore, the purpose of this invention is to propose a small-angle generation system and method based on magnetorheological fluid and a fine-tuning motor, to solve the trade-off between accuracy, response speed, and reliability in small-angle generation using traditional methods, and to achieve high-accuracy small-angle generation.

[0005] To achieve the above and other related objectives, the present invention provides a small-angle generation system based on magnetorheological fluid and a fine-tuning motor, comprising:

[0006] Two capacitive angular displacement sensors are used to measure the relative rotation angle between the inner and outer shafts;

[0007] An angle sensor signal acquisition module is configured to acquire two relative rotation angles measured by the two capacitive angular displacement sensors, and to transmit a difference between the two relative rotation angles to a feedback controller.

[0008] The feedback controller is configured to compare the angle difference with a preset target angle, and to calculate an angle error.

[0009] The motor drive control unit is configured to output a control signal of the angle error to a signal processing and analysis unit.

[0010] The signal processing and analysis unit is configured to analyze and process the angle error through a closed-loop control strategy, and to control the motor drive control unit and the magnetic field control unit according to the angle error, so that the relative rotation angle between the inner shaft and the outer shaft is stabilized within the target angle.

[0011] A computer is configured to display and output the relative rotation angle between the inner shaft and the outer shaft.

[0012] In an embodiment of the present application, the device further comprises:

[0013] A sample stage is installed on the upper part of the inner shaft, and the sample stage is fixed with the inner shaft and rotates together.

[0014] An inner shaft base is installed on the lower part of the inner shaft, and the inner shaft base is fixed with the outer shaft, and the inner shaft rotates relative to the inner shaft base.

[0015] An outer shaft is arranged outside the inner shaft and surrounds the inner shaft.

[0016] A magnetic field generating unit is arranged outside the outer shaft, and the bottom of the magnetic field generating unit is arranged on the device base.

[0017] A device base is installed on the lower part of the inner shaft base, and the inner shaft base rotates relative to the device base.

[0018] A device outer wall is fixedly installed on the upper part of the device base, and the device outer wall is arranged outside the magnetic field generating unit, and a gap is left between the device outer wall and the magnetic field generating unit, and the capacitive angular displacement sensor is installed outside the upper edge of the sample stage and the outer shaft and inside the device outer wall.

[0019] In an embodiment of the present application, the device further comprises:

[0020] A magneto-rheological fluid is arranged between the inner shaft and the outer shaft.

[0021] In an embodiment of the present application, the capacitive angular displacement sensor comprises a first capacitive plate, a second capacitive plate, a third capacitive plate, a fourth capacitive plate, a fifth capacitive plate, a sixth capacitive plate, a seventh capacitive plate, and an eighth capacitive plate, wherein the first capacitive plate and the second capacitive plate are oppositely arranged; the third capacitive plate and the fourth capacitive plate are oppositely arranged; the fifth capacitive plate and the sixth capacitive plate are oppositely arranged; the seventh capacitive plate and the eighth capacitive plate are oppositely arranged; the first capacitive plate and the fifth capacitive plate are mounted on the side surface of the object table; the third capacitive plate and the seventh capacitive plate are mounted on the side surface of the outer shaft; the second capacitive plate, the fourth capacitive plate, the sixth capacitive plate, and the eighth capacitive plate are fixedly mounted on the inner side of the outer wall of the device; the first capacitive plate and the second capacitive plate, and the fifth capacitive plate and the sixth capacitive plate are used to measure the rotation angle of the object table relative to the inner shaft; the third capacitive plate and the fourth capacitive plate, and the seventh capacitive plate and the eighth capacitive plate are used to measure the rotation angle of the outer shaft relative to the device base.

[0022] In an embodiment of the present application, the device further comprises:

[0023] A magnetic fluid microsphere array is arranged at the lower part of the object table, and the magnetic fluid microsphere array is arranged on the upper surface of the outer shaft.

[0024] In an embodiment of the present application, a plurality of pit arrays are etched on the upper surface substrate of the outer shaft, and one magnetic fluid microsphere is placed in each pit array, which together constitute the magnetic fluid microsphere array.

[0025] In an embodiment of the present application, the magnetic field generating unit comprises a first vertical direction electromagnetic coil, a second vertical direction electromagnetic coil, a third vertical direction electromagnetic coil, a fourth vertical direction electromagnetic coil, and a first horizontal direction electromagnetic coil.

[0026] The first vertical direction electromagnetic coil and the second vertical direction electromagnetic coil are oppositely arranged on both sides of the magnetic fluid.

[0027] The third vertical direction electromagnetic coil and the fourth vertical direction electromagnetic coil are oppositely arranged, the third vertical direction electromagnetic coil is arranged on the upper part of the object table, and the fourth vertical direction electromagnetic coil is arranged on the lower part of the inner shaft base.

[0028] The first horizontal direction electromagnetic coil is arranged on the outer side of the outer shaft.

[0029] The present application also provides a small-angle generating method based on a magnetic fluid and a fine adjustment motor, which comprises the small-angle generating system based on a magnetic fluid and a fine adjustment motor as described above, and the small-angle generating method based on a magnetic fluid and a fine adjustment motor comprises the following steps.

[0030] S1, measuring the relative rotation angle between the inner shaft and the outer shaft by two capacitive angular displacement sensors;

[0031] S2, collecting the relative rotation angles measured by the two capacitive angular displacement sensors through an angle sensor signal acquisition module, and subtracting the two relative rotation angles to transmit the angle difference to a feedback controller;

[0032] S3, the feedback controller compares the angle difference with a preset target angle, calculates the angle error, and the feedback controller performs feedback control on the motor drive control unit;

[0033] S4, the motor drive control unit outputs the control signal of the angle error to a signal processing and analysis unit;

[0034] S5, the signal processing and analysis unit analyzes and processes the angle error through a closed-loop control strategy, so as to control the motor drive control unit and the magnetic field control unit according to the angle error, so that the relative rotation angle between the inner shaft and the outer shaft is stabilized within the target angle;

[0035] S6, displaying and outputting the relative rotation angle between the inner shaft and the outer shaft by a computer.

[0036] In an embodiment of the present application, the signal processing and analysis unit in step S5 analyzes and processes the angle error through a closed-loop control strategy, so as to control the motor drive control unit and the magnetic field control unit according to the angle error, so that the relative rotation angle between the inner shaft and the outer shaft is stabilized within the target angle, comprising:

[0037] For the first, second, third, fourth, fifth, sixth, seventh and eighth capacitive plates, assuming that the initial plate overlap area is A0, the dielectric constant between the plates is ε, and the plate spacing is d, when the angle changes Δθ, the change of the plate overlap area is ΔA, then the relationship between the capacitance change ΔC and the angle change Δθ is approximately:

[0038]

[0039] Assuming that the radius of the sector plate is r, the overlap area caused by the angle change is approximately:

[0040]

[0041] Then the angle change Δθ can be expressed as:

[0042]

[0043] The small angle generating system works in a shear mode, in which the magneto-rheological fluid is confined between two counter-rotating shafts, at this time, the shear rate omega is related to the force F, and the expression is:

[0044]

[0045] The formula (4) is simplified as:

[0046]

[0047] Wherein, F 屈服 (H) is a static yield stress related to the magnetic field, which is independent of the angle; is a viscous damping coefficient; is an angular velocity; A is a shear area, r is a rotation radius, d is a gap thickness, and η is a zero-field viscosity; F in the formula is a force caused by a shear stress, when an external torque is applied, the generated angle is divided into two modes of stable rotation and dynamic response.

[0048] In an embodiment of the present application, the stable rotation mode is:

[0049] Suppose that the small angle generating system reaches a steady state, at this time, the external torque and the damping torque of the magneto-rheological fluid are balanced, and the obtained steady-state angle change is:

[0050]

[0051] Wherein, θ0 is an initial angle value, T ext is a torque generated by the fine motor, and t is an angle change time;

[0052] The dynamic response mode is:

[0053] Suppose that the small angle generating system is a transient change, and the obtained transient angle change is:

[0054]

[0055] Wherein, C1 and C2 are determined by initial conditions, and l is the total length of the flow path of the magneto-rheological fluid.

[0056] As described above, the small angle generating system and method based on the magneto-rheological fluid and the fine motor have the following beneficial effects:

[0057] The small angle generating system and method based on the magneto-rheological fluid and the fine motor utilize the fast solidification characteristics (millisecond response) of the magneto-rheological fluid under the magnetic field, combine the step driving of the fine motor, realize instantaneous locking after angle adjustment, and avoid the hysteresis and looseness of the traditional mechanical locking.

[0058] The small angle generation system and method based on magneto-rheological fluid and fine adjustment motor of the application adopt closed-loop adaptive algorithm, combine motor encoder signal and magneto-rheological fluid damping feedback, realize dynamic compensation of angle fine adjustment, combine motor micro-step subdivision drive and magneto-rheological fluid damping vibration suppression characteristics, and achieve high-accuracy small angle generation.

[0059] The small angle generation system and method based on magneto-rheological fluid and fine adjustment motor of the application adopt high-resolution fine adjustment motor, combine damping compensation technology of magneto-rheological fluid, eliminate mechanical transmission gap, realize millisecond level angle resolution, and far exceed angle resolution of traditional mechanical fine adjustment device.

[0060] The small angle generation system and method based on magneto-rheological fluid and fine adjustment motor of the application realize angle real-time adjustment by combining magneto-rheological fluid and fine adjustment motor drive under the action of magnetic field within 1-5 ms, and there is no drift after locking.

[0061] The small angle generation system and method based on magneto-rheological fluid and fine adjustment motor of the application replace traditional mechanical locking mechanism with magneto-rheological fluid, reduce component quantity, are compact in size, and have remarkable effect in high-precision manufacturing, angle attitude control and other fields. BRIEF DESCRIPTION OF DRAWINGS

[0062] Figure 1 is a structure schematic view of the small angle generation system based on magneto-rheological fluid and fine adjustment motor of one embodiment of the application;

[0063] Figure 2 is a main body structure top view of the small angle generation system based on magneto-rheological fluid and fine adjustment motor of one embodiment of the application;

[0064] Figure 3 is a flow chart of the small angle generation method based on magneto-rheological fluid and fine adjustment motor of one embodiment of the application.

[0065] Wherein: 1 - carrier round table; 2 - inner shaft; 3 - inner shaft base; 4 - outer shaft; 5 - magneto-rheological fluid; 6 - magneto-rheological fluid microsphere array; 7 - magnetic field generating unit (701 - first vertical direction electromagnetic coil; 702 - second vertical direction electromagnetic coil; 703 - third vertical direction electromagnetic coil; 704 - fourth vertical direction electromagnetic coil; 705 - first horizontal direction electromagnetic coil); 8 - device base; 9 - device outer wall; 10 - capacitance angle displacement sensor (101 - first capacitor plate; 102 - second capacitor plate; 103 - third capacitor plate; 104 - fourth capacitor plate; 105 - fifth capacitor plate; 106 - sixth capacitor plate; 107 - seventh capacitor plate; 108 - eighth capacitor plate); 11 - angle sensor signal acquisition module; 12 - feedback controller; 13 - motor drive control unit; 14 - fine adjustment motor; 15 - signal processing and analysis unit; 16 - magnetic field control unit; 17 - computer. DETAILED DESCRIPTION

[0066] The present application is described herein with reference to specific embodiments thereof which are illustrated in the attached drawings. These embodiments are described in detail to enable practitioners in the art to practice the application in various embodiments, and it is understood that the descriptions given herein are not to be taken as limiting the application. Although specific embodiments of the application can be illustrated and described herein, it is well understood that various presentment of the application (consisting of numerous alternatives, modifications, and equivalents) can be made without departing from the scope of the present application, and it is therefore desired that what is claimed should be determined by the balanced language read of the claims and specification and understood against the principles of the present application.

[0067] It is to be understood that the drawings are designed solely for purposes of illustration. In reality, the components shown in the drawings can differ considerably in shape, size, and proportions from how they are depicted in the drawings, and some of these components may not even be of regular geometric shape. Decorations shown in the drawings are not necessarily drawn to scale and may have been exaggerated or minimized for illustrative purposes.

[0068] Terms, such as first or second, can be used to describe various components, but the components are not limited by the above terms. The above terms are used to distinguish one component from another component, for example, a first component can be referred to as a second component, and likewise, a second component can be referred to as a first component, without departing from the scope of the concepts according to the present disclosure.

[0069] Also, "connected" or "coupled" means that one component is directly or indirectly connected or coupled to another component, and "connection" or "coupling" means that one component is directly or indirectly connected or coupled to another component. The singular form "a," "an," and "the" can include plural references unless the context clearly dictates otherwise. Also, the term "comprises" or "comprising" as used in the specification indicates the presence of the features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, but does not preclude the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0070] Various modifications and changes can be applied to the embodiments of the examples of the concept, so that the embodiments of the examples of the concept will be illustrated in the accompanying drawings and described in the specification. However, the embodiments of the examples of the concept are not limited to the specific embodiments, but include all changes, equivalents, or alternatives included in the spirit and technical scope of the disclosure.

[0071] It should be understood that when an element is described as "coupled" or "connected" to another element, it can be directly coupled or connected to the other element, or can be coupled or connected to the other element through a third element. Conversely, it should be understood that when an element is referred to as being "directly connected" or "directly coupled" to another element, no other element is interposed therebetween. Other expressions describing the relationship between elements (i.e., "between" and "directly between" or "adjacent" and "directly adjacent") should be interpreted in the same manner.

[0072] The terms used in the specification are only used to describe specific examples of the embodiments, and are not intended to limit the disclosure. If there is no explicit opposite meaning in the context, the singular form can include the plural form. In the specification, it should be understood that the term "comprise" or "have" indicates the presence of the features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, but cannot preclude the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0073] If not defined otherwise, all terms used herein (including technical terms or scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art. If a term is defined in the specification, it should be interpreted as having a meaning that is consistent with its meaning in the context of the relevant art, and not be interpreted in an ideal or overly formal sense unless clearly defined otherwise.

[0074] Descriptions of well-known components and processing techniques can be omitted so as not to unnecessarily obscure the embodiments of the disclosure.

[0075] Throughout the specification, same reference signs refer to same elements. Therefore, even if a reference sign is not mentioned or described with reference to one drawing, the reference sign can be mentioned or described with reference to another drawing. In addition, even if a reference sign is not shown in one drawing, the reference sign can be mentioned or described with reference to another drawing.

[0076] In addition, the logic levels of signals can be different from or opposite to the described logic levels. For example, a signal described as having a logic "high" level can alternatively have a logic "low" level, and a signal described as having a logic "low" level can alternatively have a logic "high" level.

[0077] The embodiments of the present disclosure will be described in detail below with reference to the drawings. However, those skilled in the art can understand that, in the embodiments of the present disclosure, many technical details are presented in order to enable the reader to better understand the present disclosure. However, the technical solutions claimed by the present disclosure can be implemented even without these technical details and various changes and modifications based on the following embodiments.

[0078] Please refer to Figure 1 , Figure 2 , Figure 1 is a structural schematic diagram of a small-angle generating system based on a magneto-rheological fluid and a fine-tuning motor according to an embodiment of the present disclosure; Figure 2 is a top view of a main structure of a small-angle generating system based on a magneto-rheological fluid and a fine-tuning motor according to an embodiment of the present disclosure. The present disclosure provides a small-angle generating system based on a magneto-rheological fluid and a fine-tuning motor, which comprises: two capacitive angular displacement sensors 10 for measuring the relative rotation angle between an inner shaft 2 and an outer shaft 4; an angular sensor signal acquisition module 11 for acquiring the relative rotation angles measured by the two capacitive angular displacement sensors 10, and subtracting the two relative rotation angles, and transmitting the angle difference to a feedback controller 12; the feedback controller 12 is used for comparing the angle difference with a preset target angle, calculating the angle error, and the feedback controller 12 is used for feedback control of a motor drive control unit 13; the motor drive control unit 13 is used for outputting the control signal of the angle error to a signal processing and analysis unit 15; the signal processing and analysis unit 15 is used for analyzing and processing the angle error through a closed-loop control strategy, so as to control the motor drive control unit 13 and a magnetic field control unit 16 according to the angle error, so as to stabilize the relative rotation angle between the inner shaft 2 and the outer shaft 4 within the target angle; a computer 17 is used for displaying and outputting the relative rotation angle between the inner shaft 2 and the outer shaft 4.

[0079] Specifically, the small-angle generating system based on the magneto-rheological fluid and the micro motor further comprises: a carrying table 1 installed on the upper portion of the inner shaft 2, the carrying table 1 being fixed with the inner shaft 2 and rotating together; an inner shaft base 3 installed on the lower portion of the inner shaft 2, the inner shaft base 3 being fixed with the outer shaft 4, and the inner shaft 2 being capable of rotating relative to the inner shaft base 3; the outer shaft 4 being arranged outside the inner shaft 2 and surrounding the inner shaft 2; a magnetic field generating unit 7 arranged outside the outer shaft 4, and the bottom of the magnetic field generating unit 7 being arranged on a device base 8; the device base 8 being installed on the lower portion of the inner shaft base 3, the inner shaft base 3 being capable of rotating relative to the device base 8; a device outer wall 9 fixedly installed on the upper portion of the device base 8, the device outer wall 9 being arranged outside the magnetic field generating unit 7 and leaving a gap between the device outer wall 9 and the magnetic field generating unit 7, and the capacitive angular displacement sensor 10 being installed outside the upper edge of the carrying table 1 and the outer shaft 4 and inside the device outer wall 9. The magneto-rheological fluid 5 is arranged between the inner shaft 2 and the outer shaft 4.

[0080] In an embodiment of the present application, the capacitive angular displacement sensor 10 is installed outside the upper edge of the carrying table 1 and the outer shaft 4 and inside the opposite device outer wall 9, so that the relative change in area can achieve high-accuracy measurement of the angle. The carrying table 1 is fixed with the inner shaft 2 and rotates together; the inner shaft base 3 is fixed with the outer shaft 4, and the device base 8 is fixed with the device outer wall 9. The inner shaft 2 is capable of rotating relative to the inner shaft base 3, and the inner shaft base 3 is capable of rotating relative to the device base 8.

[0081] In an embodiment of the present application, the annular space between the inner shaft 2 and the outer shaft 4 is filled with the magneto-rheological fluid 5, and the inner shaft 2 and the outer shaft 4 are respectively provided with high-precision capacitive angular displacement sensors 10. A plurality of groups of independently controllable magnetic field generating units 7 are arranged outside the outer shaft 4, on the upper surface and the lower surface of the carrying table 1, and on the upper surface and the lower surface of the inner shaft base 3, and the magnetic field generating units 7 can generate magnetic fields of different directions and strengths. The specific working principle is as follows: when there is no magnetic field, the magneto-rheological fluid 5 is in a liquid state, and the inner shaft 2 and the outer shaft 4 can rotate freely relative to each other. When a small angle needs to be generated, the small angle is ±5°, the magnetic field generating units 7 are started to generate a magnetic field inside the annular space. Under the action of the magnetic field, the magneto-rheological fluid 5 rapidly changes its rheological properties to form a local high-viscosity region. Due to the change in friction between the inner shaft 2 and the outer shaft 4, the outer shaft 4 will have a slight tendency to rotate relative to the inner shaft 2. At this time, another micro motor 13 connected to the inner shaft 2 is used to accurately control the rotation of the inner shaft 2 with extremely small torque through a connecting rod on the micro motor. The relative rotation angle between the inner shaft and the outer shaft can be accurately measured by the capacitive angular displacement sensor 10.

[0082] Specifically, the capacitive angular displacement sensor 10 comprises a first capacitive plate 101, a second capacitive plate 102, a third capacitive plate 103, a fourth capacitive plate 104, a fifth capacitive plate 105, a sixth capacitive plate 106, a seventh capacitive plate 107, and an eighth capacitive plate 108. The first capacitive plate 101 is arranged opposite to the second capacitive plate 102; the third capacitive plate 103 is arranged opposite to the fourth capacitive plate 104; the fifth capacitive plate 105 is arranged opposite to the sixth capacitive plate 106; and the seventh capacitive plate 107 is arranged opposite to the eighth capacitive plate 108. The first capacitive plate 101 and the fifth capacitive plate 105 are installed on the side surface of the object table 1; the third capacitive plate 103 and the seventh capacitive plate 107 are installed on the side surface of the outer shaft 4; and the second capacitive plate 102, the fourth capacitive plate 104, the sixth capacitive plate 106, and the eighth capacitive plate 108 are fixedly installed on the inner side of the device outer wall 9. The first capacitive plate 101 and the second capacitive plate 102, and the fifth capacitive plate 105 and the sixth capacitive plate 106 are used to measure the rotation angle of the object table 1 relative to the inner shaft 2; and the third capacitive plate 103 and the fourth capacitive plate 104, and the seventh capacitive plate 107 and the eighth capacitive plate 108 are used to measure the rotation angle of the outer shaft 4 relative to the device base 8.

[0083] In an embodiment of the present application, the first capacitive plate 101 and the second capacitive plate 102, and the fifth capacitive plate 105 and the sixth capacitive plate 106 are used to measure the rotation angle of the object table 1 relative to the inner shaft 2; and the third capacitive plate 103 and the fourth capacitive plate 104, and the seventh capacitive plate 107 and the eighth capacitive plate 108 are used to measure the rotation angle of the outer shaft 4 relative to the device base 8. The specific installation mode is as follows: the first capacitive plate 101 and the fifth capacitive plate 105 are installed on the side surface of the object table 1; the third capacitive plate 103 and the seventh capacitive plate 107 are installed on the side surface of the outer shaft 4; and the second capacitive plate 102, the fourth capacitive plate 104, the sixth capacitive plate 106, and the eighth capacitive plate 108 are fixedly installed on the inner side of the device outer wall 9. By skillfully controlling the position and strength of the magnetic field and the torque of the fine-tuning motor, a precise small angle can be generated. By adopting the double-shaft interference mode, the angle can be more flexibly adjusted, and high precision can be achieved in control accuracy.

[0084] Based on the small angle generation system of the magnetorheological fluid and the fine-tuning motor, the system further comprises a magnetorheological fluid microsphere array 6 arranged at the lower part of the object table 1. The upper surface of the outer shaft 4 is etched with a plurality of pit arrays, and one magnetorheological fluid microsphere is placed in each pit array to jointly form the magnetorheological fluid microsphere array 6.

[0085] In one embodiment of the present application, the magnetic fluid microsphere array 6 is used to assist in generating a small angle change. A micro-pit array is etched on the upper surface of the outer shaft 4, and a magnetic fluid microsphere is placed in each pit to form the magnetic fluid microsphere array 6. The objective table 1 is on the upper surface of the outer shaft 4, and the objective table 1 is fixedly connected to the inner shaft 2. The lower surface of the objective table 1 can rotate relative to the upper surface of the outer shaft 4, and there is a very thin gap between the lower surface of the objective table 1 and the upper surface of the outer shaft 4, which is just large enough to allow the magnetic fluid microspheres to contact the cover plate under the action of the magnetic field to generate a friction force.

[0086] Specifically, the magnetic field generating unit 7 includes: a first vertical direction electromagnetic coil 701, a second vertical direction electromagnetic coil 702, a third vertical direction electromagnetic coil 703, a fourth vertical direction electromagnetic coil 704, and a first horizontal direction electromagnetic coil 705. The first vertical direction electromagnetic coil 701 and the second vertical direction electromagnetic coil 702 are opposite to each other and are respectively arranged on the two sides of the magnetic fluid 5. The third vertical direction electromagnetic coil 703 and the fourth vertical direction electromagnetic coil 704 are opposite to each other, the third vertical direction electromagnetic coil 703 is arranged on the upper part of the objective table 1, and the fourth vertical direction electromagnetic coil 704 is arranged on the lower part of the inner shaft base 3. The first horizontal direction electromagnetic coil 705 is arranged on the outer side of the outer shaft 4.

[0087] In one embodiment of the present application, the first horizontal direction electromagnetic coil 705 is arranged in a circular ring shape. The positional relationship of the electromagnetic coils is that the first vertical direction electromagnetic coil 701 and the second vertical direction electromagnetic coil 702 are opposite to each other, and the third vertical direction electromagnetic coil 703 and the fourth vertical direction electromagnetic coil 704 are opposite to each other. The specific working principle of the magnetic fluid microsphere array 6 is as follows: in the initial state, the magnetic fluid microsphere array 6 is in a natural state. When a small angle of ±5° needs to be generated, the magnetic field generating unit 7 generates a magnetic field in a specific area. The magnetic fluid microsphere array 6 changes the rheological property under the action of the magnetic field, the microspheres swell and contact the lower surface of the objective table 1. Due to the increased friction between the microspheres and the lower surface of the objective table 1, when a small force is applied to the edge of the objective table 1, the objective table 1 will rotate relative to the outer shaft 4 at a small angle. By controlling the distribution and strength of the magnetic field, the swelling degree of the microspheres and the friction force can be accurately controlled, so as to accurately control the small angle rotation of the objective table 1.

[0088] In one embodiment of the present application, the capacitance angle displacement sensor 10 measures the angle value difference, and transmits the angle difference signal to the feedback controller 11. The feedback controller 11 performs feedback control on the motor drive control unit 12, compares the angle signal measured by the capacitance angle displacement sensor 10 with the target angle set by the system, and calculates the angle error. Then, according to the error signal, the rotation of the fine adjustment motor 13 and the magnetic field strength of the magnetic field control unit 15 are adjusted through a certain control strategy. The specific processing mode is as follows: a closed-loop control strategy is adopted, and after the signal processing and analysis unit 14 analyzes and processes the angle error signal, when the angle error is greater than the set threshold value, the signal processing and analysis unit 14 transmits the error signal to the motor drive control unit 12, which adjusts the rotation speed of the fine adjustment motor 13 or enhances the magnetic field strength to quickly reduce the angle error signal; when the angle error signal is small, the system fine adjusts the motor 13 and the magnetic field to stabilize the angle near the target value. Finally, the resulting angle result is displayed and output by the computer 16.

[0089] Please refer to Figure 3 , Figure 3 is a flow chart of a small angle generation method based on a magneto-rheological fluid and a fine adjustment motor according to one embodiment of the present application. The present application also provides a small angle generation method based on a magneto-rheological fluid and a fine adjustment motor, which comprises the small angle generation system based on a magneto-rheological fluid and a fine adjustment motor described above. The small angle generation method based on a magneto-rheological fluid and a fine adjustment motor comprises the following steps:

[0090] S1, measuring the relative rotation angle between the inner shaft 2 and the outer shaft 4 by two capacitance angle displacement sensors 10;

[0091] S2, collecting the relative rotation angles measured by the two capacitance angle displacement sensors 10 by the angle sensor signal acquisition module 11, and subtracting the two relative rotation angles to transmit the angle difference to the feedback controller 12;

[0092] S3, the feedback controller 12 compares the angle difference with the preset target angle to calculate the angle error, and the feedback controller 12 performs feedback control on the motor drive control unit 13;

[0093] S4, the motor drive control unit 13 outputs the control signal of the angle error to the signal processing and analysis unit 15;

[0094] S5, the signal processing and analysis unit 15 analyzes and processes the angle error through a closed-loop control strategy to control the motor drive control unit 13 and the magnetic field control unit 16 according to the angle error, so that the relative rotation angle between the inner shaft 2 and the outer shaft 4 is stabilized within the target angle;

[0095] S6, display and output the relative rotation angle between the inner shaft 2 and the outer shaft 4 by the computer 17.

[0096] The signal processing and analysis unit 15 in step S5 analyzes and processes the angle error by a closed-loop control strategy to control the motor drive control unit 13 and the magnetic field control unit 16 according to the angle error, so that the relative rotation angle between the inner shaft 2 and the outer shaft 4 is stabilized within the target angle, including:

[0097] The area type capacitive angular displacement sensor is installed on the circular object table, the outer shaft upper edge, and the opposite device outer side installation area. When the area changes relatively, high-accuracy measurement of the angle can be realized. Taking the area type single set of polar plate capacitors, i.e., the first capacitive plate 101, the second capacitive plate 102, the third capacitive plate 103, the fourth capacitive plate 104, the fifth capacitive plate 105, the sixth capacitive plate 106, the seventh capacitive plate 107, and the eighth capacitive plate 108 as an example, for the capacitive displacement sensor with a fan-shaped polar plate, assuming that the initial polar plate overlapping area is A0, the dielectric constant between the polar plates is ε, and the polar plate spacing is d, when the angle changes Δθ, the change amount of the polar plate overlapping area is ΔA, and the relationship between the capacitive change amount ΔC and the angle change Δθ can be approximately:

[0098]

[0099] Assuming that the radius of the fan-shaped polar plate is r, and the overlapping area caused by the angle change is approximately:

[0100]

[0101] Therefore, the angle change Δθ can be expressed as:

[0102]

[0103] The system works in shear mode, in which the magnetorheological fluid is confined between two rotating shaft cylinders. At this time, the shear rate ω (i.e., the derivative of the angle with respect to time ) is related, and the expression of the force F is:

[0104]

[0105] The formula is simplified as:

[0106]

[0107] Where F 屈服 (H) is the static yield stress related to the magnetic field, which is independent of the angle; is the viscous damping coefficient; is the angular velocity (i.e. the rate of change of angle); A is the shear area, r is the radius of rotation, d is the gap thickness (the gap thickness is the cross-sectional dimension of the flow path of the MR fluid), and η is the zero-field viscosity. In the shear mode, the MR fluid is placed between two axially moving cylinders, and when a magnetic field is applied, the MR fluid generates a shear stress, which is related to the shear rate (i.e. the angular velocity). F in the formula is the force caused by the shear stress, which includes two parts: a static yield force (related to the magnetic field) and a dynamic viscous force (related to the angular velocity). When an external torque (such as the torque generated by the fine adjustment motor) Text acts on it, the resulting angle is divided into two modes: stable rotation (constant angular velocity) and dynamic response (including an inertia term).

[0108] (1) Stable rotation (constant angular velocity)

[0109] Assuming that the system reaches a steady state (no angular acceleration, i.e. , at this time the external torque Text and the damping torque of the MR fluid are balanced, and the steady-state angular change obtained is:

[0110]

[0111] where θ0 is the initial angle value, T ext is the torque generated by the fine adjustment motor, and t is the angle change time.

[0112] (2) Dynamic response (including an inertia term)

[0113] Assuming that the system is in a transient state, the transient angular change obtained is:

[0114]

[0115] where C1 and C2 are determined by the initial conditions, and l is the total length of the flow path of the MR fluid.

[0116] In summary, the small-angle generating system and method based on the MR fluid and the fine adjustment motor of the present application utilizes the rapid solidification characteristics (millisecond-level response) of the MR fluid under a magnetic field, combines the step-by-step driving of the fine adjustment motor, realizes instantaneous locking after angle adjustment, and avoids the hysteresis and looseness of traditional mechanical locking. The present application adopts a closed-loop adaptive algorithm, combines the motor encoder signal and the MR fluid damping feedback, and realizes dynamic compensation of angle fine adjustment. The combination of motor micro-step subdivision driving and MR fluid damping vibration suppression characteristics achieves high-accuracy small-angle generation.

[0117] The above embodiments are only illustrative of the principles of the present application and its efficacy, and are not intended to limit the present application. Any modification or change made by any person skilled in the art without departing from the spirit and scope of the present application shall be covered by the claims of the present application.

Claims

1. A small angle generating system based on magneto-rheological fluid and a fine motor, characterized in that, The utility model relates to a kind of relative rotation angle control device for inner shaft and outer shaft, including: Two capacitive angular displacement sensors (10) are used to measure the relative rotation angle between the inner shaft (2) and the outer shaft (4); An angle sensor signal acquisition module (11) is used to acquire the relative rotation angle measured by the two capacitive angular displacement sensors (10) and to transmit the angle difference to the feedback controller (12) by differencing the two relative rotation angles; The feedback controller (12) is used to compare the angle difference with the preset target angle and calculate the angle error, and the feedback controller (12) is used to feedback control the motor drive control unit (13); The motor drive control unit (13) is used to output the control signal of the angle error to the signal processing and analysis unit (15); The signal processing and analysis unit (15) is used to analyze and process the angle error through a closed-loop control strategy to control the motor drive control unit (13) and the magnetic field control unit (16) according to the angle error, so that the relative rotation angle between the inner shaft (2) and the outer shaft (4) is stabilized within the target angle; A computer (17) is used to display and output the relative rotation angle between the inner shaft (2) and the outer shaft (4).

2. The small angle generating system based on magneto-rheological fluid and micro motor of claim 1, wherein, Further including: A sample stage (1) is installed on the upper part of the inner shaft (2), and the sample stage (1) is fixed with the inner shaft (2) and rotates together; An inner shaft base (3) is installed on the lower part of the inner shaft (2), and the inner shaft base (3) is fixed with the outer shaft (4), and the inner shaft (2) rotates relative to the inner shaft base (3); An outer shaft (4) is arranged outside the inner shaft (2) and surrounds the inner shaft (2); A magnetic field generating unit (7) is arranged outside the outer shaft (4), and the bottom of the magnetic field generating unit (7) is arranged on the device base (8); A device base (8) is installed on the lower part of the inner shaft base (3), and the inner shaft base (3) rotates relative to the device base (8); A device outer wall (9) is fixedly installed on the upper part of the device base (8), and the device outer wall (9) is arranged outside the magnetic field generating unit (7) and has a gap with the magnetic field generating unit (7), and the capacitive angular displacement sensor (10) is installed outside the upper edge of the sample stage (1) and the outer shaft (4) and inside the device outer wall (9).

3. The small angle generating system based on magneto-rheological fluid and micro motor of claim 2, wherein, Further including: A magnetorheological fluid (5) is arranged between the inner shaft (2) and the outer shaft (4).

4. The small angle generating system based on magneto-rheological fluid and micro-adjustment motor according to claim 2 or 3, characterized in that, The capacitive angular displacement sensor (10) comprises a first capacitive electrode plate (101), a second capacitive electrode plate (102), a third capacitive electrode plate (103), a fourth capacitive electrode plate (104), a fifth capacitive electrode plate (105), a sixth capacitive electrode plate (106), a seventh capacitive electrode plate (107), and an eighth capacitive electrode plate (108), wherein the first capacitive electrode plate (101) is arranged opposite to the second capacitive electrode plate (102); the third capacitive electrode plate (103) is arranged opposite to the fourth capacitive electrode plate (104); the fifth capacitive electrode plate (105) is arranged opposite to the sixth capacitive electrode plate (106); and the seventh capacitive electrode plate (107) is arranged opposite to the eighth capacitive electrode plate (108); the first capacitive electrode plate (101) and the fifth capacitive electrode plate (105) are mounted on the side surface of the object supporting circular table (1); the third capacitive electrode plate (103) and the seventh capacitive electrode plate (107) are mounted on the side surface of the outer shaft (4); the second capacitive electrode plate (102), the fourth capacitive electrode plate (104), the sixth capacitive electrode plate (106), and the eighth capacitive electrode plate (108) are fixedly mounted on the inner side of the device outer wall (9); the first capacitive electrode plate (101) and the second capacitive electrode plate (102), and the fifth capacitive electrode plate (105) and the sixth capacitive electrode plate (106) are used for measuring the rotation angle of the object supporting circular table (1) relative to the inner shaft (2); and the third capacitive electrode plate (103) and the fourth capacitive electrode plate (104), and the seventh capacitive electrode plate (107) and the eighth capacitive electrode plate (108) are used for measuring the rotation angle of the outer shaft (4) relative to the device base (8).

5. The small angle generating system based on magneto-rheological fluid and micro-adjustment motor of claim 4, wherein, Further comprising: A magnetorheological fluid microsphere array (6) arranged at the lower part of the object supporting circular table (1), and the magnetorheological fluid microsphere array (6) is arranged on the upper surface of the outer shaft (4).

6. The small angle generating system based on magneto-rheological fluid and micro-adjustment motor of claim 5, wherein: A plurality of pit arrays are etched on the upper surface substrate of the outer shaft (4), and one magnetorheological fluid microsphere is placed in each pit array, which together constitute the magnetorheological fluid microsphere array (6).

7. The small angle generating system based on magneto-rheological fluid and micro-adjustment motor of claim 3, wherein, The magnetic field generating unit (7) comprises a first vertical direction electromagnetic coil (701), a second vertical direction electromagnetic coil (702), a third vertical direction electromagnetic coil (703), a fourth vertical direction electromagnetic coil (704), and a first horizontal direction electromagnetic coil (705). The first vertical direction electromagnetic coil (701) and the second vertical direction electromagnetic coil (702) are arranged opposite to each other on the two sides of the magnetorheological fluid (5). The third vertical direction electromagnetic coil (703) and the fourth vertical direction electromagnetic coil (704) are arranged opposite to each other, the third vertical direction electromagnetic coil (703) is arranged on the upper part of the object supporting circular table (1), and the fourth vertical direction electromagnetic coil (704) is arranged on the lower part of the inner shaft base (3). The first horizontal direction electromagnetic coil (705) is arranged on the outer side of the outer shaft (4).

8. A small angle generation method based on magneto-rheological fluid and micro motor, characterized in that, The small angle generating system based on the magnetorheological fluid and the fine adjustment motor comprises the system and the method according to any one of claims 1 to 7. S1, measuring the relative rotation angle between the inner shaft (2) and the outer shaft (4) through two capacitive angular displacement sensors (10); S2, collecting the relative rotation angles measured by the two capacitive angular displacement sensors (10) through an angle sensor signal acquisition module (11), and subtracting the two relative rotation angles to transmit the angle difference to a feedback controller (12); S3, the feedback controller (12) compares the angle difference with a preset target angle, calculates the angle error, and feeds back the motor drive control unit (13); S4, the motor drive control unit (13) outputs the control signal of the angle error to the signal processing and analysis unit (15); S5, the signal processing and analysis unit (15) analyzes and processes the angle error through a closed-loop control strategy to control the motor drive control unit (13) and the magnetic field control unit (16) according to the angle error, so that the relative rotation angle between the inner shaft (2) and the outer shaft (4) is stabilized within the target angle; S6, displaying and outputting the relative rotation angle between the inner shaft (2) and the outer shaft (4) through a computer (17).

9. The small angle generation method based on magneto-rheological fluid and micro-adjustment motor of claim 8, wherein: The signal processing and analysis unit (15) in step S5 analyzes and processes the angle error through a closed-loop control strategy to control the motor drive control unit (13) and the magnetic field control unit (16) according to the angle error, so that the relative rotation angle between the inner shaft (2) and the outer shaft (4) is stabilized within the target angle, including: For the first capacitive plate (101), the second capacitive plate (102), the third capacitive plate (103), the fourth capacitive plate (104), the fifth capacitive plate (105), the sixth capacitive plate (106), the seventh capacitive plate (107), and the eighth capacitive plate (108), assuming that the initial plate overlap area is A0, the dielectric constant between the plates is ε, and the plate spacing is d, when the angle changes Δθ, the change of the plate overlap area is ΔA, then the relationship between the capacitance change ΔC and the angle change Δθ is approximately: Assuming that the radius of the sector plate is r, the overlap area caused by the angle change is approximately: Then the angle change Δθ can be expressed as: The small angle generation system works in shear mode, in which the magnetorheological fluid (5) is confined between two relatively rotating shaft cylinders, at this time, the shear rate ω is related, and the expression of the force F is: Formula (4) is simplified as: where F 屈服 (H) is the magnetic field-dependent static yield force, which is independent of the angle; is the viscous damping coefficient; is the angular velocity; A is the shear area, r is the radius of rotation, d is the gap thickness, η is the zero-field viscosity, and F in the formula is the force caused by the shear stress. When subjected to an external torque, the resulting angle is divided into two modes: stable rotation and dynamic response.

10. The small angle generation method based on magneto-rheological fluid and micro-adjustment motor of claim 9, wherein: The stable rotation mode: Assuming that the small angle generation system reaches a steady state, at this time the external torque and the damping torque of the magnetorheological fluid (5) are balanced, and the obtained steady state angle change is: where θ0 is an initial angle value, T ext is the torque generated by the fine motor, and t is the angle change time. The dynamic response mode: Assuming that the small angle generation system is in transient state, the obtained transient angle change is: Wherein, C1 and C2 are determined by the initial condition, and l is the total length of the flow path of the magnetorheological fluid (5).

Images