Six-dimensional force sensor device based on MEMS principle
A six-dimensional force sensor fabricated using MEMS technology, combined with an ASIC chip and a PCB board, overcomes the shortcomings of strain gauge sensors in terms of sensitivity, temperature drift, dynamic response, and cost, achieving high-precision and high-stability six-dimensional force measurement.
Patent Information
- Application Number
- CN202520859515.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-30
- Publication Date
- 2026-02-13
- Estimated Expiration
- 2035-04-30
AI Technical Summary
Existing strain gauge six-dimensional force sensors have shortcomings in terms of sensitivity, temperature drift, dynamic response, long-term reliability, and cost, making it difficult to meet the requirements of high precision and high stability.
A six-dimensional force sensor is fabricated on a silicon substrate using MEMS technology. Combined with an ASIC chip and PCB board, it integrates force transmission pillars, tamper-proof support structures, and flexible packaging structures to achieve high-sensitivity, low-power multi-dimensional force measurement.
It improves the sensitivity and stability of the sensor, reduces power consumption and manufacturing costs, enhances the sensor's dynamic response and environmental adaptability, and simplifies the installation process.
Smart Images
Figure CN223910392U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to sensor technical field, concretely relates to a six -dimensional force sensor device based on MEMS principle. BACKGROUND
[0002] Micro Electro Mechanical System (MEMS, Micro Electro Mechanical System), also known as micro electro mechanical system, it contains the microelectronic device made by a series of silicon / non-silicon microprocessing technology. A complete MEMS often includes micro sensor, micro actuator, micro mechanical structure, signal detection and control system etc. can independently carry out signal sensing detection, processing, transmission, its internal structure size is micron even nanometer level. The research and development of MEMS is related to material science, mechanics, microelectronics, electromagnetism, optics and multiple disciplines, the device made by MEMS technology can be used to measure force, electricity, acceleration, temperature, humidity and other physical parameters, and has the advantages of low power consumption, small size, high response speed, high sensitivity, high integration, high stability etc. It is often used as the key tool for information interaction between the outside and the inside. After decades of research and development, MEMS has been widely used in important fields such as military equipment, medical equipment, automobile industry, robot field and consumer electronic products.
[0003] Six-axis force sensor, also called six-axis force / torque sensor, six-axis force sensor, F / T sensor, is a special force sensor, which can measure three forces (FX, FY, FZ) and three torques (MX, MY, MZ) in the coordinate system (OXYZ). If the direction and point of force are randomly changed in three-dimensional space, six-axis force sensor should be selected for measurement. Because the force on any point in space can be decomposed into three directional forces (FX, FY, FZ) and three directional torques (MX, MY, MZ) along the calibration coordinate axis of the six-axis force sensor. This kind of sensor is more suitable for the situation where the reference point is far away and changes randomly, and the measurement accuracy is high. The existing six-axis force implementation methods include strain type, piezoelectric type, capacitive type, optical fiber type and photoelectric type. The strain type is mainly used in industrial robots and automobile testing, which has the advantages of low cost and good stability, but the temperature sensitivity is high and the dynamic response is limited; the piezoelectric type is mainly used for impact testing and high-speed dynamic control, which has the advantages of fast response and high stiffness, but the static measurement is limited and needs charge amplification; micro operation, precision instrument for micro operation, precision instrument, high sensitivity and temperature stability, but easy to be disturbed, and the manufacturing process is complex; optical fiber type is used in aerospace and some harsh environments, which has the advantages of strong anti-interference and high precision, but the cost is high and the installation is complex; photoelectric type is mainly used in biomedical and micro-electromechanical systems, which is non-contact and has high resolution, but the structure is complex and the environment is light sensitive. At present, the strain type six-axis force sensor occupies about 76% of the market due to its low cost and good stability, but there are still the following shortcomings:
[0004] Sensitivity and range are difficult to balance: the sensitivity of strain gauge is low (especially for metal strain gauge), which is difficult to detect small force or torque (such as millinewton level), and for scenes that require high resolution measurement (such as precision medical operation), more expensive semiconductor strain gauge or piezoelectric technology may be needed; the physical deformation range of elastomer structure is limited, and it is difficult to balance high precision and large range at the same time, and if the range is exceeded, it may directly cause plastic deformation of elastomer or damage to strain gauge.
[0005] Temperature drift and compensation are complex: the resistance value of strain gauge will fluctuate with temperature change, and the thermal expansion of elastomer material will also introduce deformation error, even if temperature compensation circuit (such as Wheatstone bridge) is used, in the environment of severe temperature change (such as aerospace or automobile high temperature test), there may still be residual drift; complex temperature compensation requires additional hardware (such as built-in temperature sensor) and algorithm support, which increases the design and maintenance cost.
[0006] Cross-interference and decoupling error: Although decoupled by the calibration matrix, the elastomer may exhibit nonlinear deformation under high load or complex stress, causing the decoupling algorithm to fail. For example, the measurement error of the axial force may be triggered unexpectedly when a large torque is applied; the calibration accuracy directly affects the measurement results, but multi-dimensional calibration requires special equipment (such as a six-degree-of-freedom loading platform), and the calibration process is time-consuming and costly.
[0007] Limited dynamic response capability: The elastomer of the strain sensor has a large mass, resulting in a low natural frequency (usually several hundred hertz), making it difficult to capture high-frequency dynamic force signals (such as rapid collision or vibration analysis of a robotic arm); there is a lag effect in the process from deformation to electrical signal output, which is not suitable for control scenarios with extremely high real-time requirements.
[0008] Long-term stability problems: Under long-term repeated load, the elastomer may exhibit creep (slow plastic deformation) or metal fatigue, causing zero drift or sensitivity to decrease, requiring regular recalibration to maintain accuracy; the adhesive of the strain gauge may also degrade due to environmental (humidity, chemical corrosion) or mechanical stress, causing signal drift or even failure.
[0009] Installation and environmental adaptability challenges: The sensor must be rigidly connected to the load, and unevenness or slight inclination of the installation surface will introduce additional moments, significantly affecting the measurement results. For example, installation errors of the end effector of a robot may cause torque data distortion; electromagnetic interference (such as motor drive signals) may also affect the weak electrical signals of the strain gauge, requiring additional shielding measures; and in humid, oily, or corrosive environments, the insufficient protection rating of the strain gauge may result in reduced lifespan.
[0010] Cost and maintenance complexity: Multi-dimensional calibration requires precision equipment and professional operation, increasing the use threshold, and once the strain gauge or elastomer is damaged, it usually needs to be returned to the factory for repair or the entire sensor module needs to be replaced, making on-site repair difficult. Utility model content
[0011] The technical problem to be solved by the utility model is to solve the deficiencies of the existing strain type six-dimensional force sensor in sensitivity, temperature drift, dynamic response, long-term reliability, and cost, and to provide a six-dimensional force sensor device based on the MEMS principle, which realizes high sensitivity, high stability, and low power consumption of multi-dimensional force measurement through micro-machining process.
[0012] To solve the above technical problems, the utility model provides a six-dimensional force sensor device based on the MEMS principle, comprising:
[0013] The MEMS six-dimensional force sensor is prepared on a silicon substrate using MEMS technology, is used to measure force and torque signals on the external X, Y, and Z axes, and converts them into analog electrical signals;
[0014] The PCB board integrated with ASIC chip and peripheral electronic elements is connected with the MEMS six-dimensional force sensor through the sensor pad, and is used for amplifying, filtering, demodulating, decoupling, calibrating and AD / DA converting analog electric signals output by the MEMS six-dimensional force sensor, and outputting digital signals.
[0015] The force conducting column is bonded or welded with the anode of the MEMS six-dimensional force sensor, and is used for transmitting external force or torque to the MEMS six-dimensional force sensor.
[0016] The anti-disassembly support structure is firmly connected with the PCB board, and the MEMS six-dimensional force sensor is isolated in the anti-disassembly support structure, so that the MEMS six-dimensional force sensor is prevented from being illegally disassembled.
[0017] The flexible packaging structure is closely attached to the force conducting column, and is used for contacting with external force and conducting the external force to the force conducting column, and protecting the force conducting column and buffering external load.
[0018] The MEMS six-dimensional force sensor is prepared on a silicon substrate through a MEMS process, and does not need a steel structure, so that the error and low efficiency problems caused by artificial pasting of strain gauges can be effectively improved, the weight and preparation cost of the sensor are reduced.
[0019] As a further description of the above technical scheme, the MEMS six-dimensional force sensor is a piezoresistive, resonant or capacitive sensor, and adopts a piezoresistive, resonant or capacitive principle; according to the application scene, if the detection accuracy requirement is strict, the resonant type is preferred; if it is desired to simplify the cost and process, the piezoresistive type is preferred.
[0020] As a further description of the above technical scheme, the sensor pad is centered on the PCB board, so that external force received by the MEMS six-dimensional force sensor can be evenly distributed on detection structures in different directions.
[0021] As a further description of the above technical scheme, the ASIC chip and the peripheral electronic elements are symmetrically arranged on the PCB board, so that after reflow soldering, the PCB board (especially at the sensor pad) has no strain and stress, so that the performance of the MEMS six-dimensional force sensor is not affected by the deformation of the PCB circuit board.
[0022] As a further description of the above technical solution, the material of the force conducting column is metal, glass or ceramic, which is connected and fixed with the MEMS six-dimensional force sensor through anodic bonding, gluing or metallization connection, preferably the glass material is firmly connected with the MEMS six-dimensional force sensor through anodic bonding, so as to accurately transmit the sensed external force / torque to the MEMS six-dimensional force sensor.
[0023] As a further description of the above technical solution, the material of the anti-disassembly support structure is hard ceramic or hard metal, preferably stainless steel or hard aluminum, a copper pad is prepared at the corresponding position of the PCB, and then the anti-disassembly support structure is firmly connected with the PCB through reflow soldering or laser welding, so as to protect the internal MEMS six-dimensional force sensor from illegal disassembly; the center of the anti-disassembly support structure is provided with an extension hole for the force conducting column to extend out, the extension hole is circular or elliptical, the aperture of the extension hole matches the range of the MEMS six-dimensional force sensor, and the anti-disassembly support structure serves as a limiting structure to prevent overload external force from damaging the MEMS six-dimensional force sensor.
[0024] As a further description of the above technical solution, the material of the packaging structure is flexible material such as silica gel, polycarbonate (PC), polyvinyl chloride (PVC) or polyimide, which is used for buffering external force or torque and protecting the force conducting column, and the packaging structure can be shaped and solidified according to the application scene, for example, when used for a robot fingertip, the packaging structure can be shaped according to the surface topography of the robot fingertip to realize perfect fitting with the robot fingertip, better sense external force and torque, and improve the detection accuracy and sensitivity of the six-dimensional force sensor device.
[0025] As a further description of the above technical solution, the packaging structure is connected with the PCB circuit board at the same time as being connected with the anti-disassembly support structure, so that the packaging is more firm and the overall reliability is improved.
[0026] The MEMS six-dimensional force sensor is prepared by the MEMS process, has high automation degree, good consistency and high alignment accuracy, does not need manual patching, has mature supply chain, and can effectively overcome the disadvantage of high installation sensitivity of strain sensors. For strain six-dimensional force sensors, the smaller the volume is, the more difficult the strain patch is, and the higher the price is. Through the MEMS process, the MEMS six-dimensional force sensors with consistent performance can be prepared in batches, the preparation cost is greatly reduced, the product volume is reduced, and the maintenance and replacement cost is reduced, so as to promote the application of the six-dimensional force sensor to the robot fingertip, the intelligent equipment execution terminal of surgical medical equipment, the end of the mechanical arm and the like.
[0027] The six-dimensional force sensor device of the utility model can overcome the limitation of low sensitivity of the prior strain device, like when the MEMS six-dimensional force sensor is realized by piezoresistance effect, because the piezoresistance coefficient of P-type silicon is much greater than that of metal, the sensitivity can be effectively improved, and the sensitivity of the MEMS six-dimensional force sensor using the resonance type amplitude modulation principle can be made higher. Through closed-loop control of the six-dimensional force sensor device, real-time compensation at different temperatures is realized, and temperature drift is reduced. Through optimization design of the six-dimensional force sensor device, the effective mass is reduced, the stiffness coefficient is improved, and the dynamic response capability of the sensor is improved, for example, the MEMS six-dimensional force sensor using the resonance principle can realize detection level of gigahertz, and because the silicon material does not have metal fatigue, combined with reasonable amplitude design, the problems of material fatigue and strain sheet aging of the traditional strain sensor can be effectively solved. BRIEF DESCRIPTION OF DRAWINGS
[0028] Figure 1 is the structure schematic diagram of the six-dimensional force sensor device of example one.
[0029] Figure 2 is the PCB board layout diagram of example one.
[0030] Figure 3 is the preparation flow chart of the six-dimensional force sensor device of example one.
[0031] Figure 4 is the structure schematic diagram of the six-dimensional force sensor device of example two.
[0032] REFERENCE NUMERALS:
[0033] 100-PCB board;101-ASIC chip;102-peripheral electronic element;200-silicon substrate;300-MEMS six-dimensional force sensor;301-sensor pad;400-force conduction column;500-anti-disassembly support structure;600-packaging structure. DETAILED DESCRIPTION
[0034] The utility model will be further described below in combination with the drawings and examples.
[0035] Example one
[0036] The embodiment provides a six-dimensional force sensor device based on MEMS principle, like Figure 1 As shown, from bottom to top, it is PCB board 100, silicon substrate 200, MEMS six-dimensional force sensor 300, force conduction column 400, anti-disassembly support structure 500 and packaging structure 600 in proper order.
[0037] The PCB 100 is welded with an ASIC chip (application specific integrated circuit chip) 101 and other peripheral electronic elements 102, which are used to amplify, filter, demodulate, decouple, calibrate and AD / DA convert the analog electrical signals output by the MEMS six-dimensional force sensor 300, and output the test results in the form of digital signals after processing. The ASIC chip 101 on the PCB 100 integrates most of the PCB-level circuit functions and is the core device of the PCB 100, which greatly reduces the overall area of the processing circuit compared to the traditional strain six-dimensional force sensor (generally containing 2-4 PCB circuit boards), and the number of electronic components also decreases sharply, reducing the volume and thickness of the entire device, reducing the design difficulty of the layout and wiring on the PCB 100, and reducing the weight of the entire device, thereby reducing the overall power consumption of the device. Moreover, the sensor pads 301 of the MEMS six-dimensional force sensor are centered on the PCB 100, which ensures that the external force received by the MEMS six-dimensional force sensor 300 is evenly distributed on the detection structure in different directions. Figure 2 As shown in FIG. 1B, the ASIC chip 101 and other peripheral electronic elements 102 are symmetrically arranged on the PCB 100, so that after reflow soldering, the PCB 100 (especially at the sensor pads) has no strain and stress, thereby ensuring that the performance of the MEMS six-dimensional force sensor 300 will not be affected by the deformation of the PCB 100.
[0038] The MEMS six-dimensional force sensor 300 is directly prepared on the silicon substrate 200 by the MEMS process, and the principle can be selected as needed, such as piezoresistive, resonant or capacitive, etc. If the detection accuracy is strict, the resonant type is preferred, and if the cost and process are desired to be simplified, the piezoresistive type is preferred.
[0039] The material of the force transmission column 400 is metal, glass or ceramic, and the connection mode with the anode of the MEMS six-dimensional force sensor 300 can be direct bonding, adhesive bonding or metallization connection, etc. The glass material is preferably connected with the anode of the MEMS six-dimensional force sensor 300 by direct bonding.
[0040] The material of the anti-disassembly support structure 500 is hard ceramic or hard metal, preferably stainless steel or hard aluminum, and a copper pad is first prepared on the corresponding position of the PCB 100, and the anti-disassembly support structure 500 and the PCB 100 are firmly connected by reflow soldering or laser welding. The center of the anti-disassembly support structure 500 is provided with an extension hole 501 for the force transmission column 400 to extend out, and the shape of the extension hole 501 is circular or elliptical, and the hole diameter is matched with the range of the MEMS six-dimensional force sensor 300, which serves as a limiting structure to prevent overload external force from damaging the MEMS six-dimensional force sensor 300.
[0041] The packaging structure 600 is connected with the anti-disassembly support structure 500, and is made of flexible materials such as silica gel, polycarbonate (PC), polyvinyl chloride (PVC) or polyimide (PI). The force transmission column 400 is protected in the packaging structure 600, and is used for protecting the force transmission column 400 and buffering external force / torque. The surface of the packaging structure 600 can be shaped according to the application scene. For example, the packaging structure 600 is used for a robot fingertip, and can be shaped and heat-cured according to the surface topography of the robot fingertip, so as to be perfectly matched with the robot fingertip, better feel external force / torque, and improve the detection accuracy and sensitivity of the device.
[0042] The preparation method of the six-dimensional force sensor device in the embodiment is shown in the flowchart as shown in Figure 3 The preparation method of the six-dimensional force sensor device in the embodiment is shown in the flowchart as shown in
[0043] S1, preparing a MEMS six-dimensional force sensor on a silicon substrate through a MEMS process;
[0044] S2, connecting the force transmission column with the anode of the MEMS six-dimensional force sensor through bonding or welding;
[0045] S3, welding the ASIC chip and the peripheral electronic elements on the PCB board, and the ASIC chip and the peripheral electronic elements are symmetrically arranged on the PCB board;
[0046] S4, welding the MEMS six-dimensional force sensor on the PCB board through the sensor pad;
[0047] S5, welding the anti-disassembly support structure on the PCB board, isolating the MEMS six-dimensional force sensor in the anti-disassembly support structure, and opening an extension hole for the force transmission column to extend in the anti-disassembly support structure, and the aperture size of the extension hole matches the range of the MEMS six-dimensional force sensor;
[0048] S6, shaping the packaging structure according to the application scene, so that the packaging structure is matched with the application scene and can be closely matched with the force transmission column; for example, shaping the packaging structure according to the surface topography of the robot fingertip, so as to be perfectly matched with the robot fingertip, and closely matched with the force transmission column, so as to better feel external force and torque, and improve the detection accuracy and sensitivity of the six-dimensional force sensor device;
[0049] S7, connecting the shaped packaging structure with the anti-disassembly support structure through heat curing.
[0050] The preparation method adopts a MEMS process to prepare a MEMS six-dimensional force sensor, has high automation degree, good consistency, high alignment precision, does not need manual patching, has a mature supply chain, and can effectively overcome the disadvantage of high installation sensitivity of a strain sensor. For a strain six-dimensional force sensor, the smaller the volume is, the more difficult the strain patching is, and the higher the price is. Through the MEMS process, the MEMS six-dimensional force sensor with consistent performance can be prepared in batches, the preparation cost is greatly reduced, the product volume is reduced, and the maintenance and replacement cost is reduced. The temperature drift is compensated in real time through an ASIC chip, the environmental adaptability is improved, the silicon-based structure is light in weight and high in rigidity, the resonance type principle can realize a gigahertz level response, the silicon material has no metal fatigue, the amplitude is optimized and designed to prolong the service life. Therefore, the six-dimensional force sensor is promoted to penetrate into applications such as a robot fingertip, a surgical medical intelligent equipment execution terminal, and a mechanical arm terminal.
[0051] Embodiment two
[0052] Compared with embodiment one, the packaging structure 600 after shaping is connected with the anti-disassembly support structure 400 and the PCB 100 at the bottom, as shown in Figure 4 The area of the packaging structure 600 is enlarged, the packaging is more firm, and the overall reliability is improved.
[0053] The above only describes the best embodiment of the present application. It should be noted that for ordinary skilled persons in the art, without departing from the principle of the present application, the technical scheme of the present application can be deformed or replaced equivalently, and the technical effect of the present application can be achieved. It should be considered as belonging to the protection scope of the present application.
Claims
1. A six-dimensional force sensor device based on MEMS principles, characterized by The application relates to a six-dimensional force sensor, which comprises the following parts: a MEMS six-dimensional force sensor, which is prepared on a silicon substrate by a MEMS process and is used for measuring force and torque signals on three axes X, Y and Z outside and converting the signals into analog electric signals; a PCB board integrated with an ASIC chip and peripheral electronic elements, wherein the MEMS six-dimensional force sensor is connected with the PCB board through sensor pads, and the PCB board is used for amplifying, filtering, demodulating, decoupling, calibrating and AD / DA converting the analog electric signals output by the MEMS six-dimensional force sensor and outputting digital signals; a force conducting column, which is connected with the anode of the MEMS six-dimensional force sensor through anode bonding or welding and is used for transmitting external force or torque to the MEMS six-dimensional force sensor; a disassembly-proof support structure, which is firmly connected with the PCB board, wherein the MEMS six-dimensional force sensor is isolated in the disassembly-proof support structure and is prevented from being illegally disassembled; and a packaging structure, which is closely combined with the force conducting column, is used for contacting with external force, transmitting external force to the force conducting column, protecting the force conducting column and buffering external load. The MEMS six-dimensional force sensor is a piezoresistive, resonant or capacitive sensor. The sensor pads are centered on the PCB board. The ASIC chip and the peripheral electronic elements are symmetrically arranged on the PCB board. The material of the force conducting column is glass, ceramic or metal, and the force conducting column is fixed with the MEMS six-dimensional force sensor through anode bonding, cementing or metallization. The material of the disassembly-proof support structure is hard ceramic or hard metal, the center of the disassembly-proof support structure is provided with an extension hole for the force conducting column to extend out, and the aperture of the extension hole matches the range of the MEMS six-dimensional force sensor.
2. The six-axis force sensor device of claim 1, wherein: The material of the packaging structure is flexible material and can be shaped according to application scenes.
3. The six-axis force sensor device of claim 1, wherein: 4. The six-axis force sensor device of claim 1, wherein: 5. The six-axis force sensor device of claim 1, wherein: 6. The six-axis force sensor device of claim 1, wherein: 7. The six-axis force sensor device of claim 1, wherein: