Force sensor based on MEMS sensitive element and capable of expanding measuring range

Abstract

The invention relates to the technical field of MEMS tactile sensor sensing modules, in particular to a force sensor with an extensible measuring range based on an MEMS sensitive element, which comprises a sensor module shell, an MEMS tactile sensor test circuit and a mechanical force transmission structure, the MEMS tactile sensor test circuit and the mechanical force transmission structure are arranged in the sensor module shell, and the mechanical force transmission structure comprises a force transmission column and an elastic body. The upper end of the force transmission column is embedded in the top face of the sensor module shell, the lower end of the force transmission column is fixed to the center of the elastic body, force applied to the top face of the sensor module shell is transmitted to the elastic body through the force transmission column, the center of the lower surface of the elastic body is fixed to an MEMS tactile sensor on the MEMS tactile sensor testing circuit, and when the force is transmitted to the elastic body, the MEMS tactile sensor is fixed to the elastic body. The bottom of the elastic body deforms, force is applied to the MEMS tactile sensor after being attenuated, and the measuring range of the sensor is expanded through force attenuation. According to the invention, the problems of small measuring range and unstable output of the MEMS sensor can be solved.

Description

Technical Field

[0001] The present invention relates to the technical field of MEMS tactile sensor sensing modules, and in particular to a force sensor with an expandable measuring range based on a MEMS sensitive element. Background Art

[0002] In recent years, sensor sensing modules have played an important role in many high-precision application fields such as industry, medical treatment, sports health, automobiles, aerospace and consumer electronics. Most of the force sensors on the market are strain gauge-mounted. The sensitivity of strain gauge sensors is easily affected by temperature, which is not suitable for complex structures. They also require precision processing and complex mounting. Force sensors based on micro-electro-mechanical system (MEMS) technology have lower manufacturing costs than traditional strain gauge force sensors, and have the advantages of low power consumption, high sensitivity and fast response. However, MEMS tactile sensor devices, especially MEMS piezoresistive sensors, currently face the problem of poor mechanical durability. Most silicon sensors have a small range, and external shock, vibration or overload may cause damage or failure of MEMS sensors. In addition, MEMS tactile sensors are highly sensitive to the environment, which may affect their performance and stability in complex environments. Summary of the invention

[0003] The purpose of the present invention is to provide a force sensor with an expandable range based on a MEMS sensitive element, so as to solve the problems of small range and unstable output faced by MEMS sensors.

[0004] In order to achieve the above object, the technical solution specifically adopted by the present invention is as follows:

[0005] A force sensor with an extendable range based on a MEMS sensitive element comprises a sensor module housing and a MEMS tactile sensor test circuit and a mechanical force transmission structure built into the sensor module housing. The sensor module housing comprises four parts: a sensor module base, a housing, a top cover and a connecting ring. The material is an aluminum alloy, which mainly plays a role in protecting the internal structure and resisting interference. The mechanical force transmission structure comprises a force transmission column and an elastomer. The upper end of the force transmission column is embedded in the top surface of the sensor module housing, and the lower end is fixed to the center position of the elastomer. The force applied to the top surface of the sensor module housing is transmitted to the elastomer through the force transmission column. The elastomer is fixed to the upper end of the connecting ring, and the center position of the lower surface of the elastomer is fixed to the MEMS tactile sensor at the lower end of the connecting ring. When the force is transmitted to the elastomer, the bottom of the elastomer is deformed, and the force is applied to the MEMS tactile sensor after attenuation, so as to expand the range of the sensor through force attenuation.

[0006] Furthermore, the sensor module base is a cylinder with a height of 5 mm and a radius of the bottom of the cylinder of 9 cm. Eight base M4 threaded bottom holes with a diameter of 3.4 mm are evenly distributed on the edge of the sensor module base for fixing the bottom of the sensor module. The material is aluminum alloy.

[0007] Furthermore, the outer ring diameter of the outer shell is 7.5 cm, the inner ring diameter is 7 cm, the outer shell height is 4 cm, and the material is aluminum alloy.

[0008] Furthermore, the top cover has a diameter of 7.5 cm, and an inner hole with a diameter of 10 mm is dug in the center for connecting the force transmission column. The top cover material is an aluminum molded alloy.

[0009] Furthermore, the inner diameter of the connecting ring is 54 mm, the outer diameter is 70 mm, and 8 M4 threaded bottom holes with a diameter of 3.4 mm are evenly distributed on the ring, which are used to fix the MEMS tactile sensor test circuit and the elastomer. The connecting ring is made of aluminum alloy.

[0010] Furthermore, the MEMS tactile sensor test circuit is fixed at the lower end of the connecting ring, and includes a PCB board, a microcontroller unit arranged on the PCB board, a MEMS tactile sensor, a data acquisition module, an on-chip temperature sensor, a wireless transmission module, a filtering electronic control, an electromagnetic interference module, a temperature interference module and an algorithm compensation module. The MEMS tactile sensor is located at the center of the PCB board, and the circuit is designed for low power consumption by optimizing the wiring of the PCB board and the MCU clock control and working mode control.

[0011] Furthermore, the elastic body includes a center platform, a connecting beam, a wheel rim and an M4 threaded bottom hole. The center platform is arranged at the center of the wheel rim through the connecting beam, and four M4 threaded bottom holes are evenly arranged on the wheel rim.

[0012] Furthermore, the force transmission column is a cylinder with a height of 10 mm and a radius of the bottom of the cylinder of 5 mm. The lower surface of the force transmission column is fixed at the center position of the center platform of the elastic body, and the upper surface is embedded in the inner hole of the top cover.

[0013] The present invention has the following characteristics and beneficial effects:

[0014] 1) The sensor module of the present invention has a sensor module base, a housing and a top cover, so that the sensor test circuit can be fixed inside the module, effectively resisting environmental interference and impact, and making the MEMS sensor output stable.

[0015] 2) The sensor module of the present invention integrates a tactile sensor test circuit, and performs low-power design and wireless transmission performance optimization on the test circuit. It enters a standby state when not in use, and has a long working time and standby time.

[0016] 3) A mechanical force transmission structure is designed in the sensor module of the present invention, which can expand the range of the tactile sensor through the force attenuation of the force transmission structure, and the mechanical force transmission structure can change the range of the sensor module by modifying the structural dimensions to meet the user's various testing needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0018] Figure 1 An exploded diagram of a force sensor with an extendable measuring range based on a MEMS sensitive element according to an embodiment of the present invention;

[0019] Figure 2 This is a three-dimensional structural diagram of a force sensor with an extendable range based on a MEMS sensitive element according to an embodiment of the present invention;

[0020] Figure 3 It is a three-dimensional structural diagram of the top cover in an embodiment of the present invention;

[0021] In the figure: (a) stereoscopic view; (b) bottom view.

[0022] Figure 4 It is a three-dimensional structural diagram of a connecting ring in an embodiment of the present invention;

[0023] Figure 5 This is a schematic diagram of the structure of the elastic body in an embodiment of the present invention;

[0024] Figure 6 A schematic diagram of a mechanical force transmission structure in an embodiment of the present invention;

[0025] Figure 7 It is a design framework of a MEMS tactile sensor test circuit in an embodiment of the present invention;

[0026] Figure 8 A schematic diagram of background algorithm calibration compensation in an embodiment of the present invention;

[0027] In the figure: sensor module base 1; housing 2; top cover 3; connecting ring 4; MEMS tactile sensor test circuit 5; elastic body 6; force transmission column 7; inner hole 200; base M4 threaded bottom hole 202; connecting ring edge M4 threaded bottom hole 400; rim 500; M4 threaded bottom hole 501; center platform 502; connecting beam 503. DETAILED DESCRIPTION

[0028] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

[0029] In order to solve the problems of small range and unstable output faced by MEMS sensors, the present invention provides a force sensor with expandable range based on MEMS sensitive elements. First, the module shell made of aluminum alloy material is used to resist environmental interference and impact. Secondly, the force attenuation effect of the mechanical force transmission structure is used to expand the range. The voltage signal is collected by the test circuit and the algorithm compensation is completed in the background to obtain the output signal of the MEMS tactile sensor, thereby solving the problems of poor mechanical durability and small range of MEMS tactile sensor devices. Specifically, Figure 1 and Figure 2 As shown, the signal sensing module includes a sensor module base 1, a shell 2, a top cover 3, a connecting ring 4, a MEMS tactile sensor test circuit 5, an elastomer 6 and a force transmission column 7. The sensor module base 1, the shell 2, the top cover 3 and the connecting ring 4 constitute the sensor module shell, and the material is aluminum alloy, which mainly plays a role in protecting the internal structure and resisting interference; the force transmission column 7 and the elastomer 6 constitute a mechanical force transmission structure, the upper end of the force transmission column 7 is embedded in the top cover 3, and the lower end is fixed at the center position of the elastomer 6. The force applied to the top cover 3 is transmitted to the elastomer 6 through the force transmission column 7. The elastomer 6 is fixed at the upper end of the connecting ring 4, and at the same time, the center position of the lower surface of the elastomer 6 is fixed to the MEMS tactile sensor on the MEMS tactile sensor test circuit 5 at the lower end of the connecting ring. When the force is transmitted to the elastomer 6, the bottom of the elastomer 6 is deformed, and the force is applied to the MEMS tactile sensor after attenuation, and the sensor range is expanded by force attenuation.

[0030] In this embodiment, the sensor module base is a cylinder with a height of 5 mm and a bottom radius of 9 cm. Eight base M4 threaded bottom holes 202 are evenly distributed on the edge of the sensor module base 1 for fixing the bottom of the sensor module to the optical platform.

[0031] like Figure 3 As shown, the top cover 3 has an inner hole 200 in the center, through which force is applied to the force transmission column 7 for force transmission. The outer diameter of the ring at the lower end of the top cover 3 is 1mm smaller than the inner diameter of the module housing 2, which is convenient for covering.

[0032] like Figure 4 As shown, eight M4 thread bottom holes 400 are evenly distributed on the edge of the connecting ring 4. Four M4 thread bottom holes 400 are used to fix the tactile sensor test circuit 5 at the lower end of the connecting ring 4, and the other four are used to fix the elastic body 6 of the force transmission structure.

[0033] like Figure 5 As shown, the elastomer 6 includes a center platform 502, a connecting beam 503, a rim 500 and an M4 threaded bottom hole 501. The center platform 502 is arranged at the center of the rim 500 through the connecting beam 503, and four M4 threaded bottom holes 501 are evenly arranged on the rim 500. The center of the lower surface of the center platform 502 is fixed to the MEMS tactile sensor on the MEMS tactile sensor test circuit 5, and the upper surface is fixed to the force transmission column 7. The material of the elastomer 6 is aluminum alloy, and its yield strength and hardness are much greater than those of the MEMS silicon sensor. When force is applied to the center platform 502 of the elastomer 6, the range of the sensor can be expanded through force attenuation. Through finite element software simulation analysis, the larger the area and the higher the height of the elastomer center platform 502, the greater the range extension; the smaller the length, the larger the width and height, and the higher the height of the elastomer connecting beam 503, the greater the range extension. According to different needs, the dimensions of the elastomer center platform 502 and the connecting beam 503 are modified to achieve a range that meets the requirements. The overall mechanical force transmission structure is as shown in FIG. Figure 6 As shown, force transmission is performed via a force transmission strut 7 .

[0034] Figure 7 The design framework of the MEMS tactile sensor test circuit 5 includes a PCB board, a microcontroller unit arranged on the PCB board, a MEMS tactile sensor, a data acquisition module, an on-chip temperature sensor, a Bluetooth transmission module, a filter electronic control, an electromagnetic interference module, a temperature interference module and an algorithm compensation module. The MEMS tactile sensor is attached to the center of the PCB board, and then the pad of the tactile sensor is wired to complete the electrical connection. The circuit is designed to be low-power by optimizing the wiring of the PCB board and the MCU clock control and working mode control. When the MEMS sensor is subjected to multiple physical signals, the force signal is converted into a voltage signal, and the data acquisition module collects the voltage signal. The microcontroller unit is AD7606. The temperature and humidity acquisition part can collect the temperature and humidity at that time in real time, and provide available data for the subsequent background algorithm compensation. The core of the Bluetooth transmission module is the Bluetooth 5.0 chip, which transmits the collected information to the host computer with low power consumption.

[0035] Figure 8 This is a schematic diagram of wireless signal transmission, host computer data processing and algorithm calibration. The temperature and humidity are acquired through the temperature and humidity acquisition module, and then the algorithm model is built to calibrate and compensate the test results.

[0036] The design of a force sensor with an extendable range based on a MEMS sensitive element of the present invention includes the following steps:

[0037] Step 1: Design the structures of the sensor module base 1, the housing 2 and the top cover 3 of the module respectively, and determine the size and material selection;

[0038] Step 2: Design the data acquisition module, wireless transmission module, temperature and humidity acquisition module, filter electronic control, electromagnetic interference module, and temperature interference module respectively, and perform low power consumption design;

[0039] Step 3: Integrate the designed circuit module and the MEMS tactile sensor on a PCB circuit board, complete the PCB circuit board welding, and obtain the MEMS tactile sensor test circuit;

[0040] Step 4, designing a mechanical force transmission structure, including an elastic body 6 and a force transmission column 7, wherein the elastic body 6 includes a center platform 502, a connecting beam 503, a wheel rim 500 and an M4 threaded bottom hole 501;

[0041] Step 5: Establish a force transmission structure simulation model, and use finite element analysis software to complete the analysis of the influence of the length, width, height of the connecting beam 503 and the height and area of ​​the center platform 502 on the range expansion of the force sensor.

[0042] Step 6: According to the measurement range requirements, reasonably design the height and area of ​​the center platform 502 and the length, width and height of the connecting beam 503.

[0043] Step 7: fix the MEMS tactile sensor test circuit to the lower end of the connecting ring 4 , and fix the mechanical force transmission structure to the upper end of the connecting ring 4 .

[0044] Step 8, cover the top cover 3 to complete the overall assembly of the sensor module, so that the upper end of the force transmission column 7 is embedded in the top cover 3, and the lower end is fixed to the center position of the elastic body 6, and the force applied to the top cover 3 is transmitted to the elastic body 6 through the force transmission column 7, and the elastic body 6 is fixed to the upper end of the connecting ring 4, and at the same time, the center position of the lower surface of the elastic body 6 is fixed to the MEMS tactile sensor on the MEMS tactile sensor test circuit 5 at the lower end of the connecting ring;

[0045] Step 9: Conduct a tactile sensor module test experiment, perform background algorithm calibration on the test results on the host computer, and obtain an algorithm compensation module.

[0046] At this point, the design of a force sensor with an extendable range based on MEMS sensitive elements has been completed.

[0047] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and descriptions are only preferred examples of the present invention and are not intended to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A force sensor with an extendable range based on a MEMS sensitive element, characterized in that: The invention comprises a sensor module housing and a MEMS tactile sensor test circuit and a mechanical force transmission structure built into the sensor module housing. The mechanical force transmission structure comprises a force transmission column and an elastomer. The upper end of the force transmission column is embedded in the top surface of the sensor module housing, and the lower end is fixed at the center position of the elastomer. The force applied to the top surface of the sensor module housing is transmitted to the elastomer through the force transmission column. The center position of the lower surface of the elastomer is fixed to the MEMS tactile sensor on the MEMS tactile sensor test circuit. When the force is transmitted to the elastomer, the bottom of the elastomer is deformed, and the force is applied to the MEMS tactile sensor after attenuation, thereby expanding the measuring range of the sensor through force attenuation.

2. A force sensor with an extendable range based on a MEMS sensitive element as claimed in claim 1, characterized in that: The sensor module housing comprises a sensor module base, a housing, a top cover and a connecting ring. The material is aluminum alloy. The elastomer is fixed to the upper end of the connecting ring. At the same time, the center position of the lower surface of the elastomer is fixed to the MEMS tactile sensor at the lower end of the connecting ring.

3. A force sensor with an extendable range based on a MEMS sensitive element as claimed in claim 2, characterized in that: The sensor module base is a cylinder with a height of 5 mm and a radius of 9 cm on the bottom of the cylinder. Eight base M4 threaded bottom holes with a diameter of 3.4 mm are evenly distributed on the edge of the sensor module base for fixing the bottom of the sensor module. The material is aluminum alloy.

4. A force sensor with an extendable range based on a MEMS sensitive element as claimed in claim 2, characterized in that: The outer ring diameter of the shell is 7.5 cm, the inner ring diameter is 7 cm, the shell height is 4 cm, and the material is aluminum alloy.

5. A force sensor with an extendable range based on a MEMS sensitive element as claimed in claim 2, characterized in that: The top cover has a diameter of 7.5 cm, and an inner hole with a diameter of 10 mm is dug in the center for connecting the force transmission column. The top cover material is an aluminum molded alloy.

6. A force sensor with an extendable range based on a MEMS sensitive element as claimed in claim 2, characterized in that: The inner diameter of the connecting ring is 54 mm, the outer diameter is 70 mm, and 8 M4 threaded bottom holes with a diameter of 3.4 mm are evenly distributed on the ring, which are used to fix the MEMS tactile sensor test circuit and the elastomer. The connecting ring is made of aluminum alloy.

7. A force sensor with an extendable range based on a MEMS sensitive element as claimed in claim 6, characterized in that: The MEMS tactile sensor test circuit is fixed at the lower end of the connecting ring, and includes a PCB board, a microcontroller unit arranged on the PCB board, a MEMS tactile sensor, a data acquisition module, an on-chip temperature sensor, a wireless transmission module, a filter electronic control, an electromagnetic interference module, a temperature interference module and an algorithm compensation module. The MEMS tactile sensor is located at the center of the PCB board.

8. The force sensor with expandable measuring range based on MEMS sensitive element as claimed in claim 1, characterized in that: The elastic body comprises a center platform, a connecting beam, a wheel rim and an M4 threaded bottom hole. The center platform is arranged at the center of the wheel rim through the connecting beam, and four M4 threaded bottom holes are evenly arranged on the wheel rim.

9. The force sensor with expandable measuring range based on MEMS sensitive element as claimed in claim 1, characterized in that: The transfer column is a cylinder with a height of 10 mm and a radius of the bottom of the cylinder of 5 mm.

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