Miniature multi-dimensional force sensor

Abstract

The invention discloses a miniature multi-dimensional force sensor, and relates to the technical field of sensors. Comprising a lower-layer shell and an MEMS multi-dimensional force sensitive core body arranged in the lower-layer shell, the MEMS multi-dimensional force sensitive core body comprises a core body mass block, a core body outer frame and at least two core body elastic beams connected with the core body mass block and the core body outer frame; the core body outer frame is rigidly connected with the lower-layer shell, the lower-layer shell further comprises at least two metal elastic beams arranged in a suspended mode, the first ends of the elastic beams are mutually connected to form an intersection, the second ends of the elastic beams are connected to the lower-layer shell, and a force transmission mass block is arranged at the intersection; wherein the lower-layer shell, the metal elastic beam and the force transmission mass block are of an integrally formed structure; and the force transfer mass block is rigidly connected with the core body mass block. The invention discloses a miniature multi-dimensional force sensor, and aims to design a miniature multi-dimensional force sensor which not only can effectively protect an internal fragile MEMS sensitive core from overload damage, but also can flexibly adjust the measuring range so as to improve the reliability and the application range of the sensor.

Description

Technical Field

[0001] This invention relates to the field of sensor technology, and in particular to a miniature multidimensional force sensor. Background Technology

[0002] Multidimensional force sensors are key components capable of simultaneously detecting force and torque information in multiple directions in three-dimensional space. They play a crucial role in cutting-edge applications such as robotics, particularly the precision manipulation of robotic grippers, precision assembly and polishing in industrial automation, and medical surgical robots. As technology advances towards miniaturization and integration, miniature multidimensional force sensors manufactured using microelectromechanical systems (MEMS) technology have become a research hotspot.

[0003] Currently, a common type of miniature multidimensional force sensor typically consists of a MEMS force-sensitive chip directly fixed to a substrate. External forces are applied directly to the central force-bearing area of ​​the MEMS chip through a force transmission structure. While this design is simple, the MEMS chip primarily uses silicon-based materials, which are inherently fragile and have limited mechanical strength. When subjected to significant impacts or overloads, the chip's elastic structure is highly susceptible to breakage, causing permanent damage to the sensor and resulting in poor reliability. Secondly, since the sensor's measurement range is mainly determined by the mechanical characteristics of the MEMS chip itself, once the chip design and manufacturing are complete, its measurement range is essentially fixed, making it difficult to flexibly adjust to adapt to different application scenarios. This limits its versatility and applicability.

[0004] Therefore, designing a miniature multidimensional force sensor that can effectively protect its fragile internal MEMS sensing core from overload damage and flexibly adjust its range to improve the sensor's reliability and applicability has become an urgent technical challenge. Summary of the Invention

[0005] The main objective of this invention is to provide a miniature multidimensional force sensor. The aim is to design a miniature multidimensional force sensor that can effectively protect its fragile internal MEMS sensing core from overload damage, and can flexibly adjust its range to improve the reliability and applicability of the sensor.

[0006] To achieve the above objectives, this invention proposes a miniature multidimensional force sensor, comprising a lower housing and a MEMS multidimensional force-sensitive core disposed within the lower housing; the MEMS multidimensional force-sensitive core includes a core mass block, a core outer frame, and at least two core elastic beams connecting the core mass block and the core outer frame; the core outer frame is rigidly connected to the lower housing, and the lower housing further includes at least two suspended metal elastic beams, the first ends of each elastic beam being interconnected to form an intersection point, the second ends of each elastic beam being connected to the lower housing, and a force-transmitting mass block being disposed at the intersection point; wherein, the lower housing, the metal elastic beams, and the force-transmitting mass block are integrally formed; the force-transmitting mass block is rigidly connected to the core mass block.

[0007] Preferably, it also includes an upper shell; the integrally formed structure of the lower shell further includes an upwardly extending intermediate force column, which is used to transmit the force applied to the upper shell to the force-transmitting mass block.

[0008] Preferably, the top of the intermediate force column is formed with a threaded connecting column, and the upper shell is provided with an internal threaded connecting hole that mates with the threaded connecting column.

[0009] Preferably, the upper housing is provided with at least one load-bearing threaded hole for connecting an external force-applying device.

[0010] Preferably, the core elastic beam of the MEMS multidimensional force-sensitive core is provided with multiple sensitive resistors.

[0011] Preferably, the lower housing is provided with a groove for accommodating the MEMS multidimensional force-sensitive core.

[0012] Preferably, the bottom of the lower housing is provided with at least one boss structure for fixing the sensor to an external device.

[0013] Preferably, the bottom of the lower housing is further provided with an FPC flexible board placement slot for placing circuit boards.

[0014] Preferably, the number of core elastic beams is the same as the number of metal elastic beams, and each metal elastic beam and the core elastic beam are structurally overlapped one-to-one.

[0015] The above technical solution offers the following advantages: it significantly improves the reliability and overload resistance of the sensor. When external forces are transmitted to the lower housing through the intermediate force column, they first act on the macroscopic, integrally formed metal elastic beams within the lower housing. These metal elastic beams, as the first-level deformation units, bear the majority of the stress and strain with their excellent toughness and strength, playing a crucial role in buffering and overload protection. This limits the forces transmitted to the internal MEMS multidimensional force-sensitive core within a safe range, effectively preventing damage to the core sensing element and significantly improving the overall sensor's impact resistance and long-term operational reliability. Furthermore, designers can easily change the overall stiffness of the sensor by adjusting the thickness, width, and other geometric parameters of the metal elastic beams. This allows for the easy development of a series of products adapted to different force range applications without altering the core MEMS sensing core. This greatly enhances design flexibility, reduces R&D costs, and broadens the sensor's applicability. Attached Figure Description

[0016] The present invention will now be described in detail with reference to specific embodiments and accompanying drawings, wherein: Figure 1 This is a schematic cross-sectional view of the overall structure of an embodiment of the present invention; Figure 2 This is a schematic diagram of the upper shell structure in an embodiment of the present invention; Figure 3 This is a schematic cross-sectional view of the lower shell structure in an embodiment of the present invention; Figure 4 This is a top view of the lower shell structure in an embodiment of the present invention; Figure 5 This is a schematic diagram of the structure of the MEMS multidimensional force-sensitive core in an embodiment of the present invention. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0018] In the description of this invention, it should be understood that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0019] Example 1 Please see Figures 1 to 5 This embodiment provides a miniature multidimensional force sensor 100. This sensor 100 offers an effective technical solution for applications such as minimally invasive surgical robots and collaborative robot fingers, which have stringent requirements for sensor size, accuracy, and reliability. While existing MEMS sensors are small in size, their silicon-based materials are relatively fragile, have limited measurement ranges, and are easily damaged by overload. Traditional strain gauge sensors, although robust, are large in size and suffer from interdimensional coupling interference. The structural design of this embodiment aims to combine the advantages of both, achieving miniaturization, high precision, and high reliability of the sensor through a heterogeneous composite structure.

[0020] Specifically, the miniature multidimensional force sensor 100 includes a lower housing 102 and a MEMS multidimensional force-sensitive core 103 disposed within the lower housing 102. The MEMS multidimensional force-sensitive core 103 is the core sensing unit for converting force signals into electrical signals. It includes a centrally located core mass block 103a, a surrounding core outer frame 103c, and at least one core elastic beam 103b connecting the core mass block 103a and the core outer frame 103c. In this embodiment, the core elastic beams 103b are preferably four, distributed in a cross-beam structure. This symmetrical structure helps to decouple forces in different dimensions. Multiple sensitive resistors 103d are fabricated at predetermined positions on each core elastic beam 103b using micro-nano fabrication technology. The layout of the sensitive resistors 103d on the surface of the symmetrical core elastic beam 103b is the same, while the layout of the sensitive resistors 103d on the surface of adjacent core elastic beams 103b is different. The sensitive resistors 103d on the surface of two beams are arranged symmetrically around the transverse midline of the beam and use two different circuit bridges to detect Fx and Fz. The sensitive resistors 103d on the surface of the other two beams are offset to one side and use the same bridge as the circuit for detecting Fx to detect Fy and Mz.

[0021] When the elastic beam 103b deforms due to force, the resistance of these sensitive resistors 103d will change accordingly, so the applied force and torque can be calculated by measuring the change in resistance.

[0022] To provide a stable and protected mounting base for the MEMS multi-dimensional force-sensitive core 103, a groove 102f is provided on the lower housing 102 to accommodate the MEMS multi-dimensional force-sensitive core 103. The outer frame 103c of the MEMS multi-dimensional force-sensitive core 103 is rigidly connected to the bottom of the groove 102f of the lower housing 102 by means of sintering or bonding. This fixing method ensures that the outer frame 103c of the core serves as a fixed reference end when the sensor is working, and the force transmission and deformation are mainly concentrated on the core elastic beam 103b and the core mass block 103a.

[0023] A core technical feature of this embodiment lies in the special structure of the lower housing 102. The lower housing 102 is not simply a base; it integrates a mechanical transmission and overload protection structure. Specifically, the lower housing 102 also includes at least four suspended metal elastic beams 102c. The second ends of these four metal elastic beams 102c are connected to the main structure of the lower housing 102, while the first ends of each elastic beam extend towards the center and connect to form a junction point. At this junction point, a force-transmitting mass block 102d is integrally provided. Crucially, the lower housing 102, the metal elastic beams 102c, and the force-transmitting mass block 102d are a single, integrally formed structure, for example, through precision metal machining. Compared to structures assembled from multiple parts, this integrated structure has higher rigidity, better force transmission consistency, and smaller assembly errors, thereby fundamentally improving the stability and measurement accuracy of the sensor.

[0024] The lower surface of the force-transmitting mass block 102d is rigidly connected to the upper surface of the core mass block 103a of the MEMS multidimensional force-sensitive core 103 through sintering or bonding. In this way, external forces can be precisely transmitted to the core force-bearing area of ​​the MEMS chip through a purely mechanical and robust structure. Simultaneously, since the external force first acts on the more rigid metal elastic beam 102c, the metal elastic beam 102c deforms first, distributing most of the impact and load, and buffering and limiting the force transmitted to the fragile MEMS core. This effectively prevents the MEMS multidimensional force-sensitive core 103 from being damaged by forces exceeding its range, greatly improving the sensor's reliability and overload resistance.

[0025] In a preferred design, the number of core elastic beams 103b is the same as the number of metal elastic beams 102c, both being four, and both employing a cross-beam structure. During assembly, each metal elastic beam 102c and core elastic beam 103b are structurally aligned and stacked one-to-one. This isomorphic stacking design ensures that the force is transmitted from the metal structure to the MEMS structure while maintaining directional consistency, effectively reducing inter-dimensional crosstalk, i.e., inter-dimensional coupling error, during force transmission. This is crucial for the performance of multi-dimensional force sensors.

[0026] To achieve force application and sensor fixation, this embodiment also includes an upper housing 101. The integrally formed structure of the lower housing 102 further includes an intermediate force column 102b extending upward from the center of the force-transmitting mass block 102d. A threaded connecting post 102a is further formed at the top of the intermediate force column 102b. Correspondingly, an internal threaded connecting hole 101a, which mates with the threaded connecting post 102a, is provided at the center of the upper housing 101. Through this threaded connection, the upper housing 101 and the lower housing 102 can be securely connected together to form a complete sensor housing. The intermediate force column 102b, as the sole force transmission path, accurately transmits the force applied to the upper housing 101 to the force-transmitting mass block 102d. It is conceivable that the upper housing 101 and the intermediate force column 102b can also be integrally formed.

[0027] The upper housing 101 is also provided with at least one load-bearing threaded hole 101b for connecting an external force-applying device. An external robotic arm, finger gripper or other device can be connected to the load-bearing threaded hole 101b by fasteners such as bolts, thereby applying external force or torque to the sensor.

[0028] For sensor mounting, the bottom of the lower housing 102 has at least one boss structure 102g. These boss structures 102g can also be machined with threaded holes for securely mounting the entire sensor onto the robot base or other external mounting equipment. Furthermore, to facilitate signal extraction, the bottom of the lower housing 102 also has an FPC flexible board placement slot 102h for placing a circuit board in the area between the boss structures 102g. The electrode pads on the MEMS multidimensional force-sensitive core 103 can be connected to the FPC flexible board covering the slot via wire bonding. The FPC flexible board then communicates with an external data acquisition system via wires or connectors.

[0029] In the operating mode of this embodiment, the side away from the core is subjected to force, while the side with the core is fixed. Specifically, the lower shell 102 is fixed by the boss structure 102g at its bottom. External force is applied to the upper shell 101 through the load-bearing threaded hole 101b. This force passes through the upper shell 101, and through the engagement of the threaded connecting post 102a and the internal threaded connecting hole 101a, it is transmitted to the intermediate force post 102b, and then sequentially to the force-transmitting mass block 102d. Since the force-transmitting mass block 102d is rigidly connected to the core mass block 103a, the core mass block 103a will move accordingly. The outer frame 103c of the core is rigidly fixed to the lower shell 102 and remains stationary. In this way, a relative displacement occurs between the core mass block 103a and the outer frame 103c of the core, causing the core elastic beam 103b connecting them to deform, thereby causing a change in the resistance value of the sensitive resistor 103d on the beam, ultimately realizing the measurement of multidimensional forces.

[0030] Example 2 This embodiment discloses another operating mode of the miniature multidimensional force sensor 100 described in Embodiment 1. The physical structure of the sensor is exactly the same as that in Embodiment 1, but the force application method and fixing method are reversed, that is, the side with the core is subjected to force, and the side away from the core is fixed.

[0031] In this operating mode, the upper housing 101 is connected to the external fixed structure through the load-bearing threaded hole 101b, at which point the upper housing 101 becomes the fixed end. The external force to be measured is applied to the lower housing 102. For example, the external device can act directly on the body of the lower housing 102, or it can be connected to the force-applying device through the boss structure 102g at its bottom.

[0032] When a force is applied to the lower housing 102, the lower housing 102 will move. Since the outer frame 103c of the MEMS multidimensional force-sensitive core 103 is rigidly connected to the lower housing 102, the outer frame 103c will move along with the lower housing 102. At the same time, the core mass block 103a is connected to the fixed upper housing 101 through the force-transmitting mass block 102d, the intermediate force column 102b, and the threaded connection column 102a, so the position of the core mass block 103a remains relatively stationary.

[0033] This creates a relative displacement between the moving outer frame 103c and the stationary core mass block 103a, which in turn causes deformation of the core elastic beam 103b and a change in the resistance of the sensitive resistor 103d. By measuring these changes in resistance, the multidimensional forces applied to the lower shell 102 can still be accurately calculated.

[0034] This reversible operating mode allows the same sensor structure to flexibly adapt to different installation and application requirements, greatly enhancing the versatility and practicality of the design. Whether the sensor is used as a tactile unit at the end of a robot's finger or as a force measuring platform fixedly mounted on a platform, the structure of this invention is competent.

[0035] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A miniature multidimensional force sensor, comprising a lower housing and a MEMS multidimensional force-sensitive core disposed within the lower housing; the MEMS multidimensional force-sensitive core comprising a core mass block, a core outer frame, and at least two core elastic beams connecting the core mass block and the core outer frame; the core outer frame being rigidly connected to the lower housing, characterized in that, The lower shell further includes: at least two suspended metal elastic beams, the first ends of each elastic beam are connected to each other to form an intersection point, the second ends of each elastic beam are connected to the lower shell, and a force-transmitting mass block is provided at the intersection point; wherein, the lower shell, the metal elastic beams and the force-transmitting mass block are integrally formed structures; the force-transmitting mass block is rigidly connected to the core mass block.

2. The miniature multidimensional force sensor as described in claim 1, characterized in that, It also includes an upper shell; the integrally formed structure of the lower shell also includes an upwardly extending intermediate force column, which is used to transmit the force applied to the upper shell to the force-transmitting mass block.

3. The miniature multidimensional force sensor as described in claim 2, characterized in that, The top of the intermediate force column is formed with a threaded connecting column, and the upper shell is provided with an internal threaded connecting hole that mates with the threaded connecting column.

4. The miniature multidimensional force sensor as described in claim 2, characterized in that, The upper housing is provided with at least one load-bearing threaded hole for connecting an external force-applying device.

5. The miniature multidimensional force sensor as described in claim 1, characterized in that, The core elastic beam of the MEMS multidimensional force-sensitive core is provided with multiple sensitive resistors.

6. The miniature multidimensional force sensor as described in claim 1, characterized in that, The lower housing has a groove for accommodating the MEMS multidimensional force-sensitive core.

7. The miniature multidimensional force sensor as described in claim 1, characterized in that, The bottom of the lower housing is provided with at least one boss structure for fixing the sensor to an external device.

8. The miniature multidimensional force sensor as described in claim 1, characterized in that, The bottom of the lower housing is also provided with an FPC flexible board placement slot for placing circuit boards.

9. The miniature multidimensional force sensor as described in claim 1, characterized in that, The number of core elastic beams is the same as the number of metal elastic beams, and each metal elastic beam is structurally superimposed on the core elastic beam.

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