Torque sensor, mechanical finger, and robot system

Abstract

The utility model relates to a torque sensor, a mechanical finger and a robot system, comprising a base, a capacitance digital conversion circuit, a processing module, a fixed block and a support column, the fixed block is used for physically connecting a stress assembly, and the support column prevents the fixed block from normal pressing deformation; at least two transformation units symmetrical around the supporting column are arranged between the base and the fixing block, the projection area of the transformation units is smaller than that of the fixing block, and the transformation units and the fixing block are mechanically coupled; the surface, opposite to the base, of the conversion unit is provided with a moving electrode, a static electrode located on the base is arranged below the moving electrode, the static electrode and the static electrode are insulated, and the surface precision of the static electrode is larger than that of the fixed block and / or other areas of the base. The fixed block is stressed to drive the conversion unit to generate micron-order distance change between the moving electrode and the static electrode at most; the capacitance digital conversion circuit obtains capacitance between the moving electrode and the static electrode; the processing module outputs an electric signal representing the torque according to the difference between the capacitors.

Description

Technical Field

[0001] This utility model relates to the measurement of torque, and more particularly to a torque sensor, a mechanical finger, and a robot system. Background Technology

[0002] Currently, extensive research reveals that capacitive six-dimensional force sensors all employ the parallel plate capacitance principle to sense XYZ three-dimensional forces and XYZ three-dimensional torques. Accurate measurement and consistency of the sensor require extremely high machining precision on the parallel plate surfaces to sense distance changes at any point on the two opposite surfaces. Simultaneously, it is crucial to ensure that the two opposite surfaces of each assembled parallel plate remain parallel, resulting in very stringent installation requirements. Furthermore, in capacitive six-dimensional force sensors based on parallel plate capacitance, the elastic beam is integral; regardless of where the force / torque is applied, it affects other directions. The decoupling algorithm for the six-dimensional force is extremely complex, as any change will require the correlation and correction of many parameters within the algorithm.

[0003] All of the above reasons contribute to the following: 1. The high price of capacitive six-dimensional force sensors, starting at tens of thousands of yuan, is prohibitive. Key joints in robots all require torque measurement, and a single robot needs dozens of torque sensors. The exorbitant sensor cost becomes an unacceptable economic obstacle to the development of high-end robots. 2. It is difficult to further miniaturize the overall size of capacitive six-dimensional force sensors. The six-dimensional force sensor is cylindrical in shape, and the smallest known size is a sensor manufactured in Japan, measuring Φ9.6X9mm. Previously, capacitive six-dimensional force sensors were used in industrial robotic arm joints. The robotic arm joints have sufficient space to accommodate large sensors and power transmission lines. Robot systems need to sense the torque effect of forces on the joints. The sensor is mounted at the joint of a segment. Currently, the size of the six-dimensional force sensor almost completely fills the joint cross-section, interfering with the power transmission lines between segments. Sensors used in robot systems should be as small as possible.

[0004] Our company previously applied for patent No. 202411542130.8, proposing a flexible electrode mechanical sensor structure for the purpose of detecting surface tactile sensation. It can measure force and torque, and the center uses a spring deformation, which has a large deformation amount, making it difficult to break through the lower limit of the sensor volume.

[0005] On the other hand, the current consensus on robotic systems is that they must possess surface tactile capabilities. Robotic systems themselves already possess three-dimensional force perception through surface tactile sensing. Sensors in robotic applications do not necessarily require six-dimensional perception like industrial robotic arms. Sensors can detect only torque, working in conjunction with the robot's surface tactile sense to form a system sensing of force and torque. For applications requiring only torque measurement, there is room for further reduction in sensor size. Utility Model Content

[0006] To address the shortcomings of existing technologies, this invention aims to provide a sensor that measures only torque.

[0007] As a solution, the torque sensor of this utility model includes a base, a detection component, a capacitance-to-digital conversion circuit, and a processing module. The detection component includes at least a fixed block constituting the sensor detection connection end and a support column extending in the normal direction from the bottom of the fixed block. The fixed block is used to physically connect to an external force-bearing component to establish a mechanical coupling between the two. The top of the support column is connected to the fixed block, and the bottom is fixed to the base. The support column acts as a first limiting member to prevent the normal compression deformation of the fixed block. At least two transformation units are arranged between the base and the fixed block. Each transformation unit is arranged symmetrically or axially about the support column. The projected area of ​​the transformation unit relative to the base is smaller than the projected area of ​​the fixed block relative to the base. There is mechanical coupling between the transformation unit and the fixed block. The conversion unit has a moving electrode on the surface of the base, and at least one stationary electrode is disposed below each moving electrode on the base. The projection of the moving electrode relative to the stationary electrode covers at least a portion of the area of ​​the corresponding stationary electrode. The moving electrode is insulated from the stationary electrode. The surface accuracy of the stationary electrode is greater than the surface accuracy of the non-stationary electrode area on the surface of the fixed block and / or the surface of the base. The difference in surface accuracy between the moving electrode and the stationary electrode is less than a set threshold. When the fixed block is subjected to force, the conversion unit can generate at most a micrometer-level spacing change between the moving electrode and the stationary electrode. A capacitance-to-digital conversion circuit is coupled to the corresponding electrode to obtain the capacitance between the moving electrode and the stationary electrode. A processing module is coupled to the capacitance-to-digital conversion circuit to output an electrical signal characterizing the torque based on the difference between the capacitances.

[0008] The torque sensor provided by this utility model also includes the following auxiliary solutions:

[0009] The transformation unit is fixed to the base and / or the fixed block, and includes at least one bent electrode formed by an elastic conductor. The bent electrode serves as a moving electrode and generates a preload on the corresponding stationary electrode through bending. The fixed block is forced to drive the transformation unit to change the distance and indirect contact area between the moving electrode and the stationary electrode. The bent electrode and the corresponding stationary electrode in the transformation unit form a symmetrical structure along the geometric center line of the projected area of ​​the stationary electrode relative to the moving electrode along the length direction of the stationary electrode.

[0010] With the extension direction of the support column as the Z-axis, a first transformation unit, a second transformation unit, a third transformation unit, and a fourth transformation unit are set between the base and the fixed block; the first transformation unit and the third transformation unit are distributed along the X-axis, and the second transformation unit and the fourth transformation unit are distributed along the Y-axis.

[0011] The processing module outputs an electrical signal representing the X-axis torque based on the difference in capacitance between the first and third transformation units, and / or outputs an electrical signal representing the Y-axis torque based on the difference in capacitance between the second and fourth transformation units.

[0012] Each conversion unit has a first static electrode and a second static electrode below it, and the first static electrode and the second static electrode are symmetrical along the geometric center line.

[0013] In this process, the extension direction of the support column is taken as the Z-axis, and the processing module outputs an electrical signal representing the Z-axis torque based on the difference in capacitance between the first static electrode and the second static electrode.

[0014] The transformation unit is a curved electrode, which can be a circular ring electrode or an elliptical ring electrode.

[0015] In this configuration, the top and / or bottom of the bent electrode are bent to form a first insert portion, and the base and / or fixing block are provided with a mounting hole for mounting the first insert portion; or, the base and / or fixing block extend protruding toward the bent electrode to form a first insert portion, and the bent electrode is provided with a mounting hole for mounting the first insert portion.

[0016] The conversion unit is provided with a second limiting member on the side or in the middle. The second limiting member serves as an overload protection component for the torque in the corresponding direction and is used to form an obstacle after the conversion unit is deformed under pressure beyond the maximum range.

[0017] The second limiting member is a limiting post extending from one of the base and the fixing block to the other, and there is a gap between the limiting post and the other corresponding to the maximum range.

[0018] The conversion unit is made of stainless steel strip.

[0019] The projected area of ​​the transformation unit relative to the base is less than 20% of the projected area of ​​the fixed block relative to the base.

[0020] The fixing block and the support column are integrally formed.

[0021] The fixing block has mounting holes on its sidewalls for locking to the load-bearing component; and / or the fixing block is a housing component of the non-load-bearing surface of the load-bearing component.

[0022] The base is a PCB board with a hole in the middle; the lower part of the support column forms an inlay part with a reduced outer diameter, which is embedded in the hole in the middle of the PCB board. The junction between the inlay part and the rest of the support column has a step for snapping onto the top surface of the base.

[0023] The base and / or fixing block have passageways for threading wires.

[0024] A mechanical finger is also provided, wherein the knuckle of the mechanical finger is provided with a force-receiving component for surface contact and the aforementioned torque sensor.

[0025] A robotic system is also provided, including the aforementioned mechanical fingers.

[0026] The torque sensor of this invention has advantages such as small size, compact structure, low cost, easy processing, reduced precision machining area and requirements, controllable accuracy, and anti-interference. Attached Figure Description

[0027] Figure 1a The first-view structure of the three-dimensional torque sensor of this invention is presented. Figure 1b The second-view structure of the three-dimensional torque sensor of this invention is presented. Figure 1c A front view of the three-dimensional torque sensor of this invention is shown.

[0028] Figure 2a A schematic diagram of a three-dimensional torque sensor installed on a knuckle is given. Figure 2b The structure of the opening in the side wall of the fixing block is given.

[0029] Figure 3 Various possible design styles of the transformation unit as a bent electrode are presented.

[0030] Figure 4 A schematic diagram is given of forming a circular or elliptical ring electrode by coiling a metal strip.

[0031] Figure 5a A diagram of the first fixing method is given. Figure 5b A diagram of the second fixing method is given.

[0032] Figure 6a A schematic diagram of the arrangement of the four transformation units is given. Figure 6b The diagram illustrates the differences in how the torsion of the fixed block causes the left and right units of the support column to move. Figure 6c A schematic diagram of the arrangement of the two static electrodes inside the unit is given. Detailed Implementation

[0033] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention.

[0034] Figures 1a to 1c The structure of the three-dimensional torque sensor of this utility model is illustrated.

[0035] The torque sensor includes a base 100 and a detection component 200. The base 100 uses a PCB board as the substrate, which facilitates the miniaturization of the sensor size. The capacitance-to-digital converter (CDC) circuit and the processing module are integrated on the PCB board.

[0036] The detection component 200 includes a fixing block 210 forming the sensor detection connection end and a support column 220 extending in the normal direction from the bottom of the fixing block 210. The fixing block 210 and the support column 220 are integrally formed, saving assembly space and reducing the sensor size. The detection component 200 is made of a high-hardness rigid material such as metal or composite material, reducing the impact of beam deformation on the measurement, while ensuring sufficient rigidity of the support column 220. The top of the support column 220 is connected to the fixing block 210, and the bottom is fixed to the base 100, forming a normal direction (Z direction as shown in the figure), serving as a first limiting element to prevent normal compression deformation of the fixing block 210. The fixing block 210 is used to physically connect to an external force-bearing component to establish a mechanical coupling between them. The external force on the force-bearing component is transmitted to the fixing block 210 through the coupling path, allowing it to undergo torsional deformation in the X, Y, and / or Z directions, while the Z-direction compression is counteracted by the support column 220.

[0037] In one alternative implementation, the force-bearing component may include a support member, such as a knuckle of a robotic finger, and an electronic skin surrounding the support member. The support member supports and shapes the knuckle into a biomimetic shape, and may be, for example, a shell or other support member within the knuckle. The electronic skin surrounding the support member provides surface tactile sensing. As an example of one application, a torque sensor may be optionally mounted at the joint of the knuckle or other segments of the robot, mechanically coupled to the support member via a linkage or other physical connection. See also Figure 2a For miniaturization purposes, the coupling method preferably uses the fixed block 210 as a component of the housing of the non-force-bearing surface 320 of the force-bearing component. The fixed block 210 is located on the non-force-bearing surface 320 and does not directly bear force. The pressure point of the finger occurs on the force-bearing surface 310, and the force is transmitted to the torque sensor, causing the detection component 200 to twist and deform. The fixed block 210 directly serves as a component of the housing of the non-force-bearing surface 320. There is no need to install connecting structures such as linkages or other connecting structures above the fixed block 210 to increase the sensor's position, saving on connecting structures and assembly components between the connecting structure and the fixed block 210. (Reference) Figure 2b The radial thickness of the sidewall can be fully utilized. By opening the mounting hole 211 on the sidewall of the fixing block 210 for locking to the force-bearing component, the micro screws can be radially installed to the load-bearing component as the sidewall component. This also saves the design of the connection structure and assembly parts required for the force coupling of the fixing block, and reduces the size of the sensor.

[0038] See Figure 1a At least two transformation units 400 are provided between the base 100 and the fixing block 210, and each transformation unit 400 is arranged symmetrically or axially around the support column 220. Figures 1a to 1cThe exemplary structure constitutes a three-dimensional torque sensor, including four transformation units 400, two of which are distributed along the X direction with the support column 220 as the center of symmetry, and the other two are distributed along the Y direction with the support column 220 as the center of symmetry. At the same time, two static electrodes 500 are provided at the bottom of each transformation unit 400. It should be understood that in some situations where it is not necessary to measure all three-dimensional torques, the torque sensor structure of this invention can be modified and reduced. For example, it can be configured as a one-dimensional X-axis torque sensor with only two transformation units 400 distributed along the X-axis, symmetrically centered on the support column 220, and each transformation unit 400 having a static electrode 500 at its bottom; or, it can be configured as a one-dimensional Y-axis torque sensor with two transformation units 400 distributed along the Y-axis, symmetrically centered on the support column 220, and each transformation unit 400 having a static electrode 500 at its bottom; or, it can be configured as a two-dimensional XY-axis torque sensor with four transformation units 400, two along the X-axis and two along the Y-axis, and a static electrode 500 at its bottom; or, it can be configured as a two-dimensional XZ-axis torque sensor with only two transformation units 400 distributed along the X-axis, symmetrically centered on the support column 220, and each transformation unit 400 having two static electrodes 500 at its bottom, etc. The above description of the preferred symmetrical distribution of transformation units around the support column describes the design style of a one-dimensional, two-dimensional, or three-dimensional torque sensor. In some alternative embodiments, the transformation units of the torque sensor can form a point-symmetric distribution structure around the support column. For example, the torque sensor includes three transformation units 400, each transformation unit 400 is evenly distributed around the support column to form a point symmetry, and each transformation unit 400 has one or two static electrodes 500 at its bottom to construct a two-dimensional or three-dimensional torque sensor.

[0039] See Figure 1a The conversion unit 400 has a moving electrode on the surface of the base 100. At least one stationary electrode 500 is disposed below each moving electrode on the base 100, and the projection of the moving electrode relative to the stationary electrode 500 at least covers a portion of the area of ​​the corresponding stationary electrode 500. The moving electrode is insulated from the stationary electrode 500. In an optional embodiment, a thin insulating film with a high dielectric constant is disposed on the stationary electrode 500 for isolation. Figure 1aIn this circuit, the conversion unit 400 and the fixed block 210 are mechanically coupled. This coupling can be achieved through connection or pressing. The twisting of the fixed block 210, through this mechanical coupling, causes the moving electrode to undergo at least a change in spacing relative to the stationary electrode 500. Given the sensor size design and the rigid deformation of the detection component 200, this spacing change is on the micrometer scale. Therefore, the projected area of ​​the conversion unit 400 relative to the base 100 is set smaller than the projected area of ​​the fixed block 210 relative to the base 100. The surface precision of the stationary electrode 500 is greater than the surface precision of the areas on the surface of the fixed block 210 and / or the base 100 where the stationary electrode 500 is located. The difference in surface precision between the moving electrode and the stationary electrode 500 is less than a set threshold, resulting in equal or similar precision. In the circuit, a capacitance-to-digital conversion circuit is coupled to the corresponding electrode to obtain the capacitance between the moving electrode and the stationary electrode 500. A processing module is coupled to the capacitance-to-digital conversion circuit to output an electrical signal characterizing the torque based on the difference in capacitance. In one optional method, one of the moving electrode and the stationary electrode 500 can be connected to the excitation terminal of the CDC and the other to the input terminal to obtain the mutual capacitance between the moving electrode and the stationary electrode 500; in another optional method, the moving electrode is grounded, and both the excitation terminal and the input terminal of the CDC are connected to the stationary electrode 500 to obtain the self-capacitance of the stationary electrode 500 to ground.

[0040] The advantages of the torque sensor structure of this utility model are: (1) The sensor structure only allows torsional deformation, and the support column design prevents the normal pressing of the fixed block. It abandons the measurement of force and only measures torque. Compared with the traditional six-dimensional force sensor, the structural complexity is reduced by a factor of two. The sensor is compact and easy to process, and can be made smaller than the current sensor. If further combined with the PCB base embedding, high-hardness integrated detection component, fixed block connection assembly design, etc., the sensor size can be reduced to 5X5mm, which can fully take into account the joint torque measurement and power routing of small space robot segments. (2) With the help of the sensor structure, the force is physically decoupled. The algorithm only needs to decouple the relationship between multi-dimensional torques, and the decoupling difficulty is reduced by a factor of two. (3) Due to the limitations of the sensor structure size, the torsional change is at the micrometer level. The reduction in capacitance amplitude caused by the small deformation is compensated by the fine machining of the surface of the moving and stationary electrodes, which is higher than other parts, to ensure that the sensor maintains high sensitivity. Only the moving and stationary electrodes are finely machined locally, and the machining area is smaller than that of traditional parallel plate six-dimensional force sensors. In addition, the sensor structure is simplified and no complex decoupling is required, which greatly reduces the cost of the sensor and has significant economic benefits for multiple torque detection applications. (4) The transformation unit is symmetrically arranged around the support column. The measurement of the transformation unit on the left and right sides of the support column is based on differential to remove common-mode interference such as environmental temperature and humidity, thereby improving measurement sensitivity and anti-interference performance.

[0041] As an optional improvement, the conversion unit 400 includes at least one bent electrode formed via an elastic conductor. Figure 3Various possible designs for the transformation unit 400 as a bent electrode are shown. The transformation unit 400 can be formed from a single metal strip or by combining multiple metal strips; the transformation unit 400 as a whole can be composed of a bent electrode, or it can have a structure with a bent lower part and an unbent upper part. To simplify the structure and manufacturing process, the transformation unit 400 is preferably made by rolling up a single metal strip, with the whole serving as a bent electrode. See also [example description missing]. Figure 4 Taking a circular shape as an example, a circular or elliptical ring electrode is formed by curling a metal strip. To achieve miniaturization, the metal strip of the conversion unit 400 is made of stainless steel to meet the requirement of reducing the strip width to 1mm. The bent electrode is fixed to the base 100 and / or the fixing block 210. In an optional embodiment, for ease of processing, see [reference needed]. Figure 5a The top and / or bottom of the bent electrode are bent to form a first insert portion, and the base 100 and / or fixing block 210 have mortise holes for mounting the first insert portion; or, see Figure 5b The base 100 and / or the fixing block 210 extend toward the curved electrode to form a first insert portion, and the curved electrode has a fitting hole for mounting the first insert portion.

[0042] In this improved scheme, the curved electrode serves as the aforementioned moving electrode. By bending, it generates a pre-pressure on the corresponding stationary electrode 500. The fixed block 210, under force, drives the transformation unit 400 to change the distance and indirect contact area between the moving electrode and the stationary electrode 500. The curved electrode in the transformation unit 400 and the corresponding stationary electrode 500 form a symmetrical structure along the geometric center line of the projected area of ​​the stationary electrode 500 relative to the moving electrode along the length direction of the stationary electrode 500. The further advantages of this improved sensor structure are: (1) The moving electrode is a curved electrode, requiring only high precision on the surface of the part that can indirectly contact the stationary electrode 500 within the range of the moving electrode, resulting in a small area; (2) By forming a pre-pressure, the processing precision requirements are reduced; (3) The capacitance change is greatly increased by the change in contact area; (4) Both the curved electrode and the stationary electrode are symmetrical about their own centers. When the fixed block twists and deforms, the left and right sides inside the unit change simultaneously, doubling the deformation and increasing the sensitivity.

[0043] refer to Figure 6a Furthermore, taking the extension direction of the support column 220 as the Z-axis, a first transformation unit 410, a second transformation unit 420, a third transformation unit 430, and a fourth transformation unit 440 are arranged between the base 100 and the fixing block 210; the first transformation unit 410 and the third transformation unit 430 are distributed along the X-axis, and the second transformation unit 420 and the fourth transformation unit 440 are distributed along the Y-axis. (Reference) Figure 6bDuring measurement, the torsion of the fixed block 210 along the X-axis causes one of the first transformation unit 410 and the third transformation unit 430, symmetrically positioned along the support column 220, to be pressed down while the other is pulled up. This creates a difference in the indirect contact area between the moving and stationary electrodes on both sides, reflecting the torsion. The processing module outputs an electrical signal representing the X-axis torque based on the difference in capacitance between the first and third transformation units 400. Similarly, the torsion of the fixed block 210 along the Y-axis creates a difference in the indirect contact area between the moving and stationary electrodes on both sides of the second transformation unit 420 and the fourth transformation unit 440. The processing module outputs an electrical signal representing the Y-axis torque based on the difference in capacitance between the second and fourth transformation units 400. Based on the above, it can be understood that when two or four transformation units are axially symmetric, the difference is considered in terms of the difference between two measurement results in the X-axis direction and / or the difference between two measurement results in the Y-axis direction. Then, corresponding to axial symmetry, such as if there are three transformation units, the force on each transformation unit can be obtained by decomposing it into two results in the X-axis direction or two results in the Y-axis direction through trigonometric functions. Then, the X-axis results are compared with the X-axis results, and the Y-axis results are compared with the Y-axis results to form a difference analysis.

[0044] Figure 6a In this structure, an electrode can be placed at the bottom of each conversion unit 420, forming an XY-axis two-dimensional torque sensor. Further details can be found in the documentation. Figure 6c Each conversion unit 400 has a first stationary electrode 510 and a second stationary electrode 520 disposed below it, and the first stationary electrode 510 and the second stationary electrode 520 are symmetrical along the aforementioned geometric center line. The moving electrode is also a symmetrical ring that twists along the Z-axis. That is, when it twists circumferentially, the area of ​​the moving electrode indirectly contacting the first stationary electrode 510 and the second stationary electrode 520 will differ. This difference reflects the circumferential twisting situation. The processing module outputs an electrical signal characterizing the Z-axis torque based on the difference in capacitance between the first stationary electrode 500 and the second stationary electrode 500. Figure 6c In the design, the first stationary electrode 510 and the second stationary electrode 520 have an opening 110 in between, which serves as the aforementioned mounting hole for the first embedding part formed by bending the bottom of the bent electrode. For miniaturization, the PCB board has an opening 120 in the middle, and the lower part of the support post 220 forms an embedding part with a reduced outer diameter. The embedding part is embedded in the hole 120 in the middle of the PCB board, and the junction between the embedding part and the rest of the support post 220 has a step for engaging the top surface of the PCB board.

[0045] Furthermore, a second limiting member is provided on the side or in the middle of the conversion unit 400. This second limiting member acts as an overload protection component against torque in the corresponding direction, preventing the conversion unit 400 from being unable to recover its deformation after overload, thus avoiding sensor performance degradation / damage. See also Figure 5bThe second limiting member is a limiting post extending from one of the base 100 and the fixing block 210 to the other, and there is a gap between the limiting post and the other corresponding to the maximum range.

[0046] As an alternative improvement, the projected area of ​​the transformation unit 400 relative to the base 100 is less than 20% of the projected area of ​​the fixing block 210 relative to the base 100.

[0047] As an alternative improvement, the base 100 and / or the fixing block 210 have passageways on their surfaces for wire threading. A partial hollow design, which differs from rigidity, can be considered to allow for the routing of power transmission wires in the knuckles.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit the scope of protection of this utility model. Although this utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this utility model without departing from the essence and scope of the technical solutions of this utility model.

Claims

1. A torque sensor, characterized in that: Includes a base, detection components, a capacitor-to-digital converter circuit, and a processing module; The detection component includes at least a fixed block constituting the sensor detection connection end and a support column extending from the bottom of the fixed block in the normal direction. The fixed block is used to physically connect to an external force-bearing component to establish a mechanical coupling between the two. The top of the support column is connected to the fixed block, and the bottom is fixed to the base. The support column serves as a first limiting member to prevent the fixed block from deforming in the normal direction. At least two transformation units are provided between the base and the fixed block. Each transformation unit is arranged symmetrically or axially around the support column. The projected area of ​​the transformation unit relative to the base is smaller than the projected area of ​​the fixed block relative to the base. There is mechanical coupling between the transformation unit and the fixed block. The surface of the conversion unit relative to the base has a moving electrode, and at least one stationary electrode is disposed below each moving electrode on the base. The projection of the moving electrode relative to the stationary electrode covers at least a portion of the area of ​​each corresponding stationary electrode. The moving electrode is insulated from the stationary electrode. The surface accuracy of the stationary electrode is greater than the surface accuracy of the area of ​​the fixed block surface and / or the base surface where the non-stationary electrode is located. The difference in surface accuracy between the moving electrode and the stationary electrode is less than a set threshold. When the fixed block is subjected to force, the conversion unit can generate at most a micrometer-level spacing change between the moving electrode and the stationary electrode. A capacitance-to-digital conversion circuit couples the corresponding electrode to obtain the capacitance between the moving electrode and the stationary electrode. The processing module is coupled with a capacitor-to-digital converter circuit, which outputs an electrical signal representing torque based on the difference between capacitors.

2. The torque sensor according to claim 1, characterized in that: The conversion unit is fixed to the base and / or the fixed block, including at least one bent electrode formed by an elastic conductor. The bent electrode serves as the moving electrode. The bending shape of the moving electrode generates a preload on the corresponding stationary electrode. The fixed block is forced to drive the conversion unit to change the distance and indirect contact area between the moving electrode and the stationary electrode. The curved electrode and the corresponding stationary electrode in the transformation unit form a symmetrical structure along the geometric center line of the projected area of ​​the stationary electrode relative to the moving electrode along the length direction of the stationary electrode.

3. The torque sensor according to claim 2, characterized in that: With the extension direction of the support column as the Z-axis, a first transformation unit, a second transformation unit, a third transformation unit, and a fourth transformation unit are set between the base and the fixed block; the first transformation unit and the third transformation unit are distributed along the X-axis, and the second transformation unit and the fourth transformation unit are distributed along the Y-axis.

4. The torque sensor according to claim 3, characterized in that: The processing module outputs an electrical signal representing the X-axis torque based on the difference in capacitance between the first and third conversion units, and / or outputs an electrical signal representing the Y-axis torque based on the difference in capacitance between the second and fourth conversion units.

5. The torque sensor according to claim 2, 3 or 4, characterized in that: Below each conversion unit are a first static electrode and a second static electrode, which are symmetrical about the geometric center line.

6. The torque sensor according to claim 5, characterized in that: Taking the extension direction of the support column as the Z-axis, the processing module outputs an electrical signal representing the Z-axis torque based on the difference in capacitance between the first static electrode and the second static electrode.

7. The torque sensor according to claim 2, characterized in that: The transformation unit is a curved electrode, and / or the transformation unit is a circular ring electrode or an elliptical ring electrode.

8. The torque sensor according to claim 7, characterized in that: The top and / or bottom of the bent electrode are formed into a first insert by bending, and the base and / or fixing block are provided with a fitting hole for mounting the first insert; Alternatively, the base and / or fixing block protrude toward the curved electrode to form a first insert portion, and the curved electrode has a fitting hole for mounting the first insert portion.

9. The torque sensor of claim 2, wherein: A second limiting member is provided on the side or in the middle of the conversion unit. The second limiting member serves as an overload protection component for the torque in the corresponding direction and is used to form an obstacle after the conversion unit is deformed under pressure exceeding the maximum range.

10. The torque sensor of claim 9, wherein: The second limiting member is a limiting post extending from one of the base and the fixing block to the other, with a gap between the limiting post and the other corresponding to the maximum range.

11. The torque sensor of claim 2, wherein: The conversion unit is made of stainless steel strip.

12. The torque sensor of claim 1, wherein: The projected area of ​​the transformation unit relative to the base is less than 20% of the projected area of ​​the fixed block relative to the base.

13. The torque sensor of claim 1, wherein: The fixing block and the support column are integrally formed.

14. The torque sensor of claim 13, wherein: The sidewall of the fixing block has mounting holes for locking to the load-bearing component; and / or the fixing block is a housing component of the non-load-bearing surface of the load-bearing component.

15. The torque sensor according to claim 1, characterized in that: The base is a PCB board with a hole in the middle. The lower part of the support column forms an inlay with a reduced outer diameter. The inlay is embedded in the hole in the middle of the PCB board. The junction between the inlay and the rest of the support column has a step for snapping onto the top surface of the PCB board.

16. The torque sensor of claim 1, wherein: The base and / or fixing block surface has passageways for threading wires.

17. A mechanical finger, characterized by The mechanical finger is provided with a force-receiving component for surface contact and a torque sensor as described in any one of claims 1-16.

18. A robot system, characterized in that, Including the mechanical finger as described in claim 17.

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