Connecting rod type single-shaft torque sensor

Abstract

The invention discloses a connecting rod type single-shaft torque sensor which comprises a cylindrical sensing piece, a connecting rod, a movable connecting rod, a supporting suspension beam arm, a photonic crystal cavity and a fixed silicon block, and the two sides of the movable connecting rod are connected with the supporting suspension beam arm, are in a suspended state and are located on the side face of the fixed silicon block. The connecting rod is used for connection, one side of the connecting rod is connected with the cylindrical sensing piece, and the other side of the connecting rod is connected with the movable connecting rod, so that the rotary motion of the cylindrical sensing piece is converted into horizontal displacement motion, and the horizontal displacement motion is transmitted to the movable connecting rod to drive the movable connecting rod to move. The photonic crystal cavity comprises a movable cavity wall and a fixed cavity wall, the movable cavity wall is located at the tail end of the movable connecting rod, the fixed cavity wall is located on one side of the fixed silicon block, and when the movable connecting rod moves horizontally, an air gap between the fixed cavity wall and the movable cavity wall changes. Compared with a traditional torque sensor, the connecting rod type single-shaft torque sensor is adopted, the size of the sensor is greatly reduced, and the sensor can be more easily applied to various tiny fields.

Description

Technical Field

[0001] The present invention belongs to the technical field of torque measurement, and particularly relates to a connecting rod type single-axis torque sensor. Background Art

[0002] A single-axis torque sensor, as the name implies, is a sensor specifically used to measure unidirectional torsion or torque. It can convert the torsional deformation of mechanical components into electrical quantity changes, and then accurately measure the torque magnitude. Such sensors have a wide range of applications in many fields such as industrial automation, robotics, automobile manufacturing, and aerospace, and are important tools to ensure the safe and efficient operation of mechanical systems. With the progress of technology, the technology of single-axis torque sensors is also constantly developing. Modern sensors adopt a more accurate regulated power supply, more sensitive strain gauge materials, and more advanced signal processing technologies, making the measurement results more accurate and stable. At the same time, the size and weight of the sensors are also constantly decreasing, facilitating integration into various compact mechanical systems.

[0003] New types of single-axis torque sensors such as fiber optic, wireless surface acoustic wave, magnetosensitive, and laser-based sensors, although they have made technological breakthroughs and improved the measurement accuracy and application universality, still face some technical and practical challenges. Magnetosensitive sensors are very sensitive to environmental magnetic field changes, and any external magnetic interference may affect their measurement accuracy, which limits their application in strong magnetic field environments. Wireless surface acoustic wave sensors: They are greatly affected by environmental factors such as temperature and humidity and need to operate in a specific environment to achieve the best performance. Although new torque sensors have made significant progress in many aspects, they still have deficiencies in complex installation and debugging, large environmental impact, and high cost. Future research and development should focus on solving these problems to better meet the needs of the market and users.

[0004] The cavity optical torque sensor uses advanced optical technology to measure torque by analyzing the phase change of light. This change is captured by a photodetector and converted into an electrical signal, which is then analyzed by a data processing system to obtain the torque value. Due to its high sensitivity and precision, the nano-beam cavity torque sensor is very suitable for occasions requiring precise torque measurement and has demonstrated excellent performance in modern industrial applications. Existing sensor devices have complex structures, cumbersome operations, low sensitivity, and cannot be widely applied in micro fields. Especially in the production and processing technology fields with high-precision requirements, there is an urgent need for sensors with high sensitivity and simple structures. Existing sensors are all capacitive, with large sizes and low precision. Moreover, in order to increase the measurement range, capacitive comb teeth are designed, resulting in complex structures. Due to their large sizes, generally over 10 centimeters, they are not suitable for robots in micro fields. Summary of the Invention

[0005] The object of the present invention is to solve the above problems and provide a link-type uniaxial torque sensor with a simple structure, convenient use, low manufacturing cost, and high sensitivity at the same time.

[0006] To solve the above technical problems, the technical solution of the present invention is: a link-type uniaxial torque sensor, including a cylindrical sensing member, a connecting link, a movable link, a supporting cantilever beam, a photonic crystal cavity, and a fixed silicon block. The two sides of the movable link are connected to the supporting cantilever beam and are in a suspended state, located on the side of the fixed silicon block. The connecting link is used for connection. One side of the connecting link is connected to the cylindrical sensing member, and the other side of the connecting link is connected to the movable link, converting the rotational motion of the cylindrical sensing member into a horizontal displacement motion and transmitting it to the movable link to drive the movable link to move. The photonic crystal cavity includes a movable cavity wall and a fixed cavity wall. The movable cavity wall is located at the end of the movable link, and the fixed cavity wall is located on one side of the fixed silicon block. When the movable link undergoes a horizontal displacement, the air gap between the fixed cavity wall and the movable cavity wall changes.

[0007] Preferably, the cylindrical sensing member is a standard cylinder with a diameter of 1 mm and a length of 2 mm, which is used to sense the externally applied torque. When the torque is applied to it, the cylindrical sensing member will twist.

[0008] Preferably, the connecting link has a length of 1 mm and a width of 0.2 mm.

[0009] Preferably, the movable link has a width of 0.2 mm and a length of 1.5 mm, and the movement of the movable link is induced by physical measurement.

[0010] Preferably, the movable link and the fixed silicon block are fabricated in a 400-nm-thick SiN layer above a 500-μm silicon layer, and the fixed silicon block only guides the input and output light.

[0011] Preferably, the photonic crystal cavity is formed by removing the SiO2 in the middle region through photolithography technology on the middle SiO2 layer of the SOI substrate; a silicon micromachined oscillator structure is fabricated on the top silicon of the rectangular SOI substrate through micro-nano processing technology, while the bottom silicon remains unchanged.

[0012] Preferably, the cross-section of the supporting cantilever beam is a bent structure, and the number of the supporting cantilever beams is two and they are symmetrically arranged.

[0013] Preferably, the fixed silicon block is made of silicon and silicon oxide, with a length of 2 mm, a width of 1 mm, and a thickness of 0.5 mm.

[0014] The beneficial effects of the present invention are:

[0015] 1. The link-type uniaxial torque sensor provided by the present invention adopts a direct measurement method, with fewer error terms and higher accuracy.

[0016] 2. Compared with traditional torque sensors, the present invention adopts a link - type uniaxial torque sensor, and the volume of the sensor is greatly reduced, making it easier to be used in various micro - fields.

[0017] 3. Since the photonic crystal cavity of the present invention measures using optical principles, it can detect extremely small phase changes, so it is extremely sensitive to torque changes and can achieve very high measurement accuracy.

[0018] 4. The photonic crystal cavity of the present invention can work normally under harsh environments such as high temperature and high pressure, and will not lose accuracy due to environmental changes. It is applicable to multiple fields from automobile manufacturing to aerospace and then to machining, etc., and especially performs excellently in equipment tests with high - precision requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is the front - view structural schematic diagram of a link - type uniaxial torque sensor of the present invention;

[0020] Figure 2 is the top - view structural schematic diagram of the present invention;

[0021] Figure 3 is the top - view structural schematic diagram of the present invention when torque is felt;

[0022] Figure 4 is the photonic crystal cavity diagram of the present invention.

[0023] Description of reference numerals: a, cylindrical sensing member; b, connecting link; c, movable link; d, supporting cantilever; e, movable cavity wall; f, fixed cavity wall; g, fixed silicon block. DETAILED DESCRIPTION OF THE INVENTION

[0024] The following further describes the present invention in conjunction with the drawings and specific embodiments:

[0025] As Figures 1 to 4 shown, a link - type uniaxial torque sensor provided by the present invention includes a cylindrical sensing member a, a connecting link b, a movable link c, a supporting cantilever d, a photonic crystal cavity, and a fixed silicon block g. Both sides of the movable link c are connected to the supporting cantilever d, in a suspended state, and are located on the side of the fixed silicon block g. The connecting link b is used for connection. One side of the connecting link b is connected to the cylindrical sensing member a, and the other side of the connecting link b is connected to the movable link c, converting the rotational motion of the cylindrical sensing member a into a horizontal displacement motion and conducting it to the movable link c to drive the movable link c to move. The photonic crystal cavity includes a movable cavity wall e and a fixed cavity wall f. The movable cavity wall e is located at the end of the movable link c, and the fixed cavity wall f is located on one side of the fixed silicon block g. When the movable link c undergoes a horizontal displacement, the air gap between the fixed cavity wall f and the movable cavity wall e changes.

[0026] In this embodiment, the end of the movable cavity wall e installed in the movable link c is in a suspended state. The cylindrical sensing member a drives the movable cavity wall e to move through the connecting link b and the movable link c, so that the distance between the movable cavity wall e and the fixed cavity wall f changes.

[0027] The cylindrical sensing member a is a standard cylinder with a diameter of 1 mm and a length of 2 mm, which is used to sense the externally applied torque. When the torque is applied to it, the cylindrical sensing member a will twist. Specifically, when a clockwise torque acts on the end of the cylindrical sensing member a, its end will also have a clockwise torque. Since the cylindrical sensing member a is circular and, when static, the lowest point of the circle is connected to the connecting link b, when it rotates clockwise, the original lowest point will move to the left, that is, the connecting link b will follow and have a certain displacement to the left. In this embodiment, the bottom end of the cylindrical sensing member a is fixedly connected to the connecting link b. Since the connecting link b is at the lowest point of the circle and after the circle rotates clockwise, in addition to moving to the left, the lowest point also moves upward. Compared with the displacement in the horizontal direction, the displacement in the vertical direction is very small and does not affect the performance of the sensor.

[0028] The connecting link b has a length of 1 mm and a width of 0.2 mm. The left side of the connecting link b is connected to the lowest end of the cylindrical sensing member a, and the right side is connected to the movable link c. The movable link c is located on the fixed silicon block g and is suspended on the left side of the fixed silicon block g through existing etching and release processes, and is connected to the fixed silicon block g by two support cantilever walls d.

[0029] The movable link c has a width of 0.2 mm and a length of 1.5 mm, and the movement of the movable link c is induced by a physical quantity. In this embodiment, the physical quantity refers to the physical power provided by an external device, such as force, torque, etc. The movable link c and the fixed silicon block g are fabricated in a 400-nm-thick SiN layer above a 500-μm-thick silicon layer, and the fixed silicon block g only guides the input and output light.

[0030] In the initial state, the distance between the movable cavity wall e and the fixed cavity wall f is 100 nm.

[0031] The photonic crystal cavity is formed by removing the SiO2 in the middle region through photolithography technology on the middle SiO2 layer of the SOI substrate. The silicon micro-machined oscillator structure is fabricated on the top silicon of the rectangular SOI substrate through micro-nano processing technology, while the bottom silicon remains unchanged.

[0032] The cross-section of the support cantilever arm d is a bent structure, and the number of support cantilever arms d is two and they are symmetrically arranged. The fixed silicon block g is made of silicon and silicon oxide, and the fixed silicon block g has a length of 2 mm, a width of 1 mm, and a thickness of 0.5 mm.

[0033] The support cantilever d is a Z-shaped bent structure, relatively thin, and consists of three segments. The width of each segment is about 0.1 mm. It mainly supports the movable link c to make it suspended, and when the movable link c is driven by the connecting link b to displace, it can support the displaced movable link c.

[0034] In the present invention, when there is an external torque acting on the cylindrical sensing member a, the cylindrical sensing member a rotates, driving the connecting link b to move leftward. The connecting link b causes the movable link to also displace leftward, thereby changing the air gap between the movable cavity wall and the fixed cavity wall in the photonic crystal cavity. As a result, the resonant wavelength of the laser in the cavity wall gap changes.

[0035] As Figure 4 shown, the photonic crystal holes f1 are arranged in a regular hexagonal honeycomb pattern to form a photonic crystal microcavity, where f2 is the cavity air groove gap. f3 is a regular hexagonal honeycomb. The measurement process of a link-type uniaxial torque sensor is analyzed as follows:

[0036] The fixed silicon block g only guides the input and output light. The movement of the movable link c can be induced by various physical quantities. The resonant wavelength of the laser in the photonic crystal cavity on it is affected by the mechanical movement of the movable component. In the photonic crystal cavity, the distance between the movable cavity wall e and the fixed cavity wall f in the original state is 100 nm. The relationship between the cavity wall gap of the photonic crystal cavity and the resonant wavelength of the laser inside it is:

[0037] m*λ = 2n c L;

[0038] where λ is the resonant wavelength, n c is the effective refractive index, and L is the cavity wall gap of the photonic crystal cavity.

[0039] When the cylindrical sensing member a senses an external torque, it will deflect clockwise or counterclockwise. Its deflection is transmitted to the movable link c through the connecting link b, causing the movable link c to displace horizontally. Its displacement causes the gap between the movable cavity wall e and the fixed cavity wall f in the photonic crystal cavity to change, thereby causing the resonant wavelength of the laser in the photonic crystal cavity to be affected. Since the change in its wavelength has a linear relationship with the change in displacement, and the change in displacement has a linear relationship with the external torque, the corresponding torque magnitude can be measured by measuring the corresponding wavelength change.

[0040] Those of ordinary skill in the art will realize that the embodiments described herein are provided to assist the reader in understanding the principles of the present invention, and it should be understood that the scope of protection of the present invention is not limited to such specific statements and embodiments. Those of ordinary skill in the art can make various other specific deformations and combinations that do not depart from the essence of the present invention based on these technical revelations disclosed in the present invention, and these deformations and combinations are still within the scope of protection of the present invention.

Claims

1. A connecting rod type single-axis torque sensor, characterized in that: The invention comprises a columnar sensing member (a), a connecting rod (b), a movable connecting rod (c), a supporting cantilever arm (d), a photonic crystal cavity and a fixed silicon block (g). The two sides of the movable connecting rod (c) are connected to the supporting cantilever arm (d), are in a suspended state, and are located on the side of the fixed silicon block (g); the connecting rod (b) is used for connection, one side of the connecting rod (b) is connected to the columnar sensing member (a), and the other side of the connecting rod (b) is connected to the movable connecting rod (c), so that the rotational motion of the columnar sensing member (a) is converted into a horizontal displacement motion, and is transmitted to the movable connecting rod (c), so as to drive the movable connecting rod (c) to move; the photonic crystal cavity comprises a movable cavity wall (e) and a fixed cavity wall (f), the movable cavity wall (e) is located at the end of the movable connecting rod (c), and the fixed cavity wall (f) is located on one side of the fixed silicon block (g), and when the movable connecting rod (c) is horizontally displaced, the air gap between the fixed cavity wall (f) and the movable cavity wall (e) changes.

2. The connecting rod type single-axis torque sensor according to claim 1, characterized in that: The cylindrical sensing member (a) is a standard cylinder with a diameter of 1 mm and a length of 2 mm, and is used to sense the torque applied externally. When the torque is applied thereto, the cylindrical sensing member (a) will be twisted.

3. The connecting rod type single-axis torque sensor according to claim 1, characterized in that: The connecting rod (b) has a length of 1 mm and a width of 0.2 mm.

4. The connecting rod type single-axis torque sensor according to claim 1, characterized in that: The movable link (c) has a width of 0.2 mm and a length of 1.5 mm, and the movement of the movable link (c) is induced by physical measurement.

5. The connecting rod type single-axis torque sensor according to claim 1, characterized in that: The movable link (c) and the fixed silicon block (g) are fabricated in a 400 nm thick SiN layer above a 500 μm silicon layer, and the fixed silicon block (g) only guides the input and output light.

6. The connecting rod type single-axis torque sensor according to claim 1, characterized in that: The photonic crystal cavity is formed by removing SiO2 in the middle area of ​​the middle SiO2 layer of the SOI substrate by photolithography technology; a silicon micromechanical oscillator structure is manufactured on the top silicon layer of the rectangular SOI substrate by micro-nano processing technology, while the bottom silicon remains unchanged.

7. The connecting rod type single-axis torque sensor according to claim 1, characterized in that: The cross section of the supporting cantilever beam arm (d) is a bent structure, and the number of the supporting cantilever beam arms (d) is two and they are symmetrically arranged.

8. The connecting rod type single-axis torque sensor according to claim 1, characterized in that: The fixed silicon block (g) is made of silicon and silicon oxide, and has a length of 2 mm, a width of 1 mm, and a thickness of 0.5 mm.

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