Six-dimensional force sensor and calibration device

Abstract

The application provides a six-dimensional force sensor and a calibration device, the six-dimensional force sensor comprising an elastic carrier and a strain gauge; wherein the elastic carrier is a spherical shell with a hollow interior and uniformly distributed hollow structures, the holes of the hollow structures forming vertical beams, and one strain gauge is fixedly attached to the center of each vertical beam. The application can effectively reduce the weight, achieve lightweight design, and has better rigidity and good load capacity, so that the six-dimensional force sensor has higher load strength. In addition, the application provides a calibration device, when the six-dimensional force sensor is calibrated using the calibration device, the pure force loading can be effectively guaranteed, no additional eccentric load is introduced, and the coupling caused by gravity is also eliminated to the greatest extent.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sensing devices, and particularly relates to a six-dimensional force sensor and a calibration device. BACKGROUND

[0002] The six-dimensional force sensor is increasingly widely applied in intelligent robots. The market share of small robots is increasingly large, mainly because the assembly of light and small components such as electronic components is gradually replaced by machines instead of manpower, and the weight control requirement of the end six-dimensional force sensor is increasingly high.

[0003] The existing elastic body structure of the six-dimensional force sensor is mainly composed of cross beams, cylindrical beams or other different numbers of beams and loading table bodies, etc. The solid metal structure arrangement makes it difficult for the current six-dimensional force sensor to be miniaturized, and also greatly increases the weight of the sensor. For example, the weight of the sensor on the current market is at least 0.5 kg, and for a 5 kg robot, the weight accounts for 10% of the robot range, which is difficult to apply to force control applications of small robots.

[0004] Therefore, the present application provides a six-dimensional force sensor, which aims to reduce the weight of the sensor and achieve extreme lightweight design under the same range requirement, and reduce the influence on the application device. SUMMARY

[0005] The present application provides a six-dimensional force sensor and a calibration device, which are used to reduce the weight of the six-dimensional force sensor and achieve lightweight design, so as to reduce the influence on the application device such as intelligent robot.

[0006] In a first aspect, a six-dimensional force sensor is provided, which is applied to a sensing device. The six-dimensional force sensor comprises an elastic carrier and a strain gauge. The elastic carrier is a spherical shell with a hollow interior and uniformly distributed hollow structures, and the holes of the hollow structures form vertical beams. One strain gauge is fixed and pasted in the center of each vertical beam. Under the same volume, the elastic carrier of the present application can greatly reduce the weight, thereby effectively reducing the weight of the six-dimensional force sensor and achieving lightweight design. According to the stress intensity = bending moment / anti-bending section modulus, the reduction of the thickness of the side wall of the elastic carrier of the present application reduces the anti-bending section modulus, greatly increases the stress intensity, enhances the rigidity, and has good bearing capacity, so that the six-dimensional force sensor has higher bearing strength.

[0007] In the specific arrangement of the hollow structure, the hollow structure is a hollow hole opened in the spherical shell, and the length direction of the hollow hole extends along the axial direction of the spherical shell.

[0008] In one specific embodiment, cross beams are fixed between adjacent vertical beams, the cross beams spanning the cutouts between adjacent vertical beams. The positions of adjacent cross beams are staggered. Specifically, adjacent cross beams are arranged above and below the strain gauges on the vertical beams in between.

[0009] In the specific arrangement of the cross beams, the thickness of the cross beams is greater than the thickness of the vertical beams, and the portions of the cross beams that are greater in thickness than the vertical beams protrude inwardly into the interior of the elastic carrier. The two ends of the cross beams are fixed to the inner walls of adjacent vertical beams, and the portions of the cross beams that are greater in thickness than the vertical beams protrude inwardly into the interior of the elastic carrier to avoid occupying the outer space of the elastic carrier.

[0010] In the specific arrangement of the vertical beams, semicircular grooves are symmetrically arranged on the upper and lower sides of the vertical beams, which can make the stress distribution of the vertical beams more concentrated in the middle, and can make the strain gauges generate greater strain output and make the six-dimensional force sensor have higher sensitivity. The cross beams are arranged above the upper semicircular grooves or below the lower semicircular grooves, which can effectively avoid the strain interference of the cross beams on the elastic carrier during loading.

[0011] In the specific arrangement of the strain gauges, the length direction of the grid wires of the strain gauges is arranged at an angle of 30°-60° with the tangential direction of the end face of the vertical beams. Further, the length directions of the grid wires of the strain gauges on any two adjacent vertical beams are consistent, and the strain gauges on any two adjacent vertical beams form a Wheatstone bridge, which is a full bridge or a half bridge.

[0012] In the further specific arrangement of the elastic carrier, a loading platform is fixed at the top end of the elastic carrier, and a fixed platform is fixed at the bottom end of the elastic carrier. The fixed platform facilitates the fixed connection of the six-dimensional force sensor to an application device, and the loading platform facilitates the fixed connection of a measured component, which facilitates the use of the six-dimensional force sensor.

[0013] In the specific arrangement of the loading platform and the fixed platform, a through hole is centrally arranged in each of the loading platform and the fixed platform, and a plurality of connecting holes are uniformly arranged around the through hole of each of the loading platform and the fixed platform. The connecting holes on the loading platform and the fixed platform facilitate the connection with an application device and a measured component. The through holes can be cancelled or retained according to the casting process and use requirements.

[0014] In a second aspect, a calibration device is provided, which includes a fixed plate, a loading plate, and a constant force spring device. The loading plate is located below the fixed plate, and a six-dimensional force sensor as described above is fixedly arranged between the loading plate and the fixed plate. The constant force spring device is fixedly supported below the loading plate and balances and offsets the weight of the loading plate, and the centers of gravity of the fixed plate, the loading plate, and the six-dimensional force sensor are collinear.

[0015] In a specific arrangement, the fixed plate is fixedly connected with the loading platform, and the loading plate is fixedly connected with the fixed platform. In addition, the loading plate has symmetrically arranged loading hooks at both ends, which are integrally fixed with the loading plate, and the loading hooks are used for hanging with the force applying device, which facilitates force loading by hanging the loading hooks above the force applying device. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 A perspective view of the six-dimensional force sensor provided by the embodiment of the present application is shown.

[0017] Figure 2 A side view of the elastic carrier provided by the embodiment of the present application is shown.

[0018] Figure 3 A bottom view of the elastic carrier provided by the embodiment of the present application is shown.

[0019] Figure 4 A structure schematic diagram of the calibration device provided by the embodiment of the present application is shown.

[0020] Figure 5 A structure schematic diagram of the six-dimensional force sensor provided by the embodiment of the present application applied to a smart robot is shown.

[0021] Figure 6 A structure schematic diagram of the six-dimensional force sensor provided by the embodiment of the present application applied to a force control surveying device is shown. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings.

[0023] In order to facilitate understanding of the six-dimensional force sensor provided by the embodiment of the present application, the application scenario of the six-dimensional force sensor will be first described. The six-dimensional force sensor is designed to reduce weight and achieve lightweight, so as to reduce the influence on the application device such as a smart robot.

[0024] Reference Figure 1 and in combination Figure 3 , Figure 1 A perspective view of the six-dimensional force sensor is shown, Figure 3 A bottom view of the elastic carrier is shown. The six-dimensional force sensor comprises an elastic carrier 1 and a strain sheet 2. The elastic carrier 1 is a hollow spherical shell uniformly provided with a hollow structure, and vertical beams 15 are formed between the holes of the hollow structure. One strain sheet 2 is fixedly adhered to the center of each vertical beam 15.

[0025] The elastic carrier 1 of the present application can greatly reduce the weight in the same volume due to the internal hollow, thereby effectively reducing the weight of the six-dimensional force sensor and achieving lightweight design; according to the stress intensity = bending moment / bending section modulus, the reduction of the thickness of the side wall of the elastic carrier 1 of the present application reduces the bending section modulus, so that the stress intensity is greatly increased, the rigidity is enhanced, and good bearing capacity is obtained, so that the six-dimensional force sensor has higher bearing strength.

[0026] As shown in Figure 1 , in one specific embodiment, the number of vertical beams 15 is eight. Of course, in other specific embodiments, the number of vertical beams 15 can also be four or six, and the specific number can be reasonably set according to the specific application scene. As a preferred scheme, the number of vertical beams 15 is preferably eight.

[0027] In the specific setting of the hollow structure, as shown in Figure 1 , the hollow structure is a hollow hole opened in the spherical shell, and the length direction of the hollow hole is along the axial direction of the spherical shell, so that the vertical beams 15 are formed between adjacent hollow holes. For example, the hollow hole can be an elliptical hole.

[0028] In one specific embodiment, a horizontal beam 12 is fixed between adjacent vertical beams 15, as shown in Figure 2 , Figure 2 , which shows a side view of the elastic carrier, and the horizontal beam 12 spans the hollow hole between adjacent vertical beams 15. It should be noted that the horizontal beam 12 is integrally connected with the vertical beam 15.

[0029] In the embodiment of the present application, the adjacent horizontal beams 12 are staggered. Specifically, the adjacent horizontal beams 12 are arranged above and below the strain sheet 2 on the vertical beam 15 therebetween. The staggered arrangement of the adjacent horizontal beams 12 helps to improve the overall structural strength of the elastic carrier 1.

[0030] According to the force analysis, the staggered arrangement of the horizontal beams 12 changes the stress change direction of the vertical beam 15 when bearing, so that the stress direction of the vertical beam 15 is rotated by 90°, and the elastic carrier 1 has a unique axial output when subjected to different direction loads by adding the horizontal beam 12.

[0031] In the specific setting of the horizontal beam 12, the thickness of the horizontal beam 12 is greater than the thickness of the vertical beam 15, and the part of the horizontal beam 12 greater than the thickness of the vertical beam 12 protrudes and extends into the elastic carrier 1. The thickness of the horizontal beam 12 is greater than the thickness of the vertical beam 15, which can help to improve the overall structural strength of the elastic carrier 1. The two ends of the horizontal beam 12 are fixed with the inner wall of the adjacent vertical beam 15, and the part greater than the thickness of the vertical beam 15 protrudes and extends into the elastic carrier 1 to avoid occupying the external space of the elastic carrier 1.

[0032] In the specific setting of the vertical beam 15, as shown in Figure 2 , the side of the vertical beam 15 is symmetrically provided with a semicircular groove 13, so that the stress distribution of the vertical beam 15 is more concentrated in the middle position, and the strain gauge 2 can obtain greater strain output, so that the six-dimensional force sensor has higher sensitivity. The horizontal beam 12 is located above the upper semicircular groove 13 or below the lower semicircular groove 13, so that the strain interference of the horizontal beam 12 to the elastic carrier 1 in use can be effectively avoided.

[0033] In the specific setting of the position relationship between the horizontal beam 12 and the semicircular groove 13, among the adjacent horizontal beams 12, the upper horizontal beam 12 is arranged above and adjacent to the upper semicircular groove 13, and the lower horizontal beam 12 is arranged below and adjacent to the lower semicircular groove 13. In this way, the strain interference of the horizontal beam 12 to the elastic carrier 1 in use can be effectively avoided.

[0034] In the specific setting of the strain gauge 2, the length direction of the grid wire of the strain gauge 2 is arranged at an angle of 30°-60° with the tangential direction of the end face of the vertical beam 15. For example, the length direction of the grid wire of the strain gauge 2 is arranged at an angle of 45° with the tangential direction of the end face of the vertical beam 15. Further, the length direction of the grid wire of the strain gauge 2 on any two adjacent vertical beams 15 is consistent, and the strain gauges 2 on any two adjacent vertical beams 15 form a Wheatstone bridge, which is a full bridge or a half bridge.

[0035] For the convenience of installation and use of the six-dimensional force sensor, referring to Figure 2 , Figure 3 , the top end of the elastic carrier 1 is fixedly provided with a loading platform 11 and the bottom end is fixedly provided with a fixed platform 14. The six-dimensional force sensor can be fixedly connected to the application device (for example, a smart robot) through the fixed platform 14, and the measured component can be fixedly connected through the loading platform 11.

[0036] In the specific setting of the loading platform 11 and the fixed platform 14, referring to Figure 1 , Figure 3 , the loading platform 11 and the fixed platform 14 are respectively provided as circular end platforms, so that the six-dimensional force sensor has more universality when connected and used. In addition, the loading platform 11 and the fixed platform 14 are respectively provided with a through hole 16 in the center, and the through hole 16 is a circular hole. In addition, the loading platform 11 and the fixed platform 12 are uniformly provided with a circle of connecting holes 17 around the respective through holes 16, and the application device and the measured component can be fixedly connected through the connecting holes 17.

[0037] In the embodiment of the present application, due to the hollow design inside the elastic carrier 1, the controller matched with the six-dimensional force sensor can be installed inside the elastic carrier 1, which can effectively improve the space utilization of the six-dimensional force sensor provided by the present application. In the present application, the through hole 16 can be cancelled or retained according to the needs of use.

[0038] As shown in Figure 5 , Figure 5 The structure schematic diagram of the six-dimensional force sensor applied to the intelligent robot is shown. In a specific application embodiment, the six-dimensional force sensor provided by the present application is applied to the intelligent robot, and in specific arrangement, the through hole 16 of the loading platform 11 of the elastic carrier 1 and the fixed platform 14 is arranged as an internal thread hole, so that the six-dimensional force sensor provided by the present application is suitable for being installed at the end of the intelligent robot finger 6, and force perception is realized.

[0039] As shown in Figure 6 , Figure 6 The structure schematic diagram of the six-dimensional force sensor applied to the force control mapping device is shown. In another application embodiment, the six-dimensional force sensor provided by the present application is applied to the force control mapping device, and in specific arrangement, the loading platform 11 of the elastic carrier 1 is connected and fixed with the probe structure 7 of the force control mapping device, and the fixed platform 14 of the elastic carrier 1 is connected and fixed with the mounting structure 8 of the force control mapping device, so that the six-dimensional force sensor provided by the present application is suitable for being installed in the force control mapping device, and the force control mapping device belongs to a precision detection device.

[0040] In addition, the present application also provides a calibration device, as shown in Figure 4 , Figure 4 The structure schematic diagram of the calibration device applied is shown, which comprises a fixed plate 3, a loading plate 4 and a constant force spring device 5. The loading plate 4 is located below the fixed plate 3, and the six-dimensional force sensor described above is fixedly arranged between the loading plate 4 and the fixed plate 3, and the constant force spring device 5 is fixedly supported below the loading plate 4 and balances and offsets the weight of the loading plate 4, and the centers of gravity of the fixed plate 3, the loading plate 4 and the six-dimensional force sensor are collinear.

[0041] In use, the six-dimensional force sensor is fixed by the fixed plate 3. In specific arrangement, the fixed plate 3 is fixedly connected with the loading platform 11, and the loading plate 4 is fixedly connected with the fixed platform 14. In addition, the loading plate 4 has symmetrically arranged loading hooks 41 at both ends, the loading hooks 41 are integrally fixed with the loading plate 4, and the loading hooks 41 are used for hanging with the force applying device, and the loading hooks 41 are hung above the force applying device to facilitate force loading.

[0042] It should be noted that the loading hook 41 is understood as a part of the loading plate 4, and the weight counteracted by the constant force spring device 5 is the weight of the loading plate 4 including the loading hook 41. The lower end of the constant force spring device 5 is fixedly supported on a certain plane or platform, and the upper end of the constant force spring device 5 is in contact with the bottom of the loading plate 4 through a ball head to exert an upward force.

[0043] When the six-dimensional force sensor provided by the application is calibrated by the calibration device, as shown in the figure, the loading of forces in each direction is realized through superposition in f1-f7 directions, and the calibration relationship is as follows: Figure 4

[0044] [F x ,F y ,F z ,M x ,M y ,M z ] T =K[U3,U4,U1+U2,U2,U1,U3+U4] T ;

[0045] Wherein, Fx is the X-direction loading force; Fy is the Y-direction loading force; Fz is the Z-direction loading force; Mx is the X-direction loading moment; My is the Y-direction loading moment; Mz is the Z-direction loading moment; U1-U4 are bridge output voltages respectively; and K is a constant.

[0046] The calibration device has the advantages that the center of gravity of the loading plate 4 is collinear with the center of gravity of the six-dimensional force sensor, and the pure force loading can be effectively guaranteed without introducing additional bias load; the constant force spring device 5 balances the weight of the loading plate 4 including the loading hook 41, and the coupling caused by gravity is eliminated to the greatest extent.

[0047] The above is only a specific embodiment of the application, but the protection scope of the application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the application, which should be covered within the protection scope of the application. Therefore, the protection scope of the application should be subject to the protection scope of the claims.​

Claims

1. A six-dimensional force sensor, characterized by The application relates to a six-dimensional force sensor. The elastic carrier is a hollow spherical shell with uniformly distributed hollow structures, and the holes of the hollow structures form vertical beams, and one strain gauge is fixedly arranged on each vertical beam. The hollow structure is a hollow hole formed in the spherical shell, and the length direction of the hollow hole extends along the axial direction of the spherical shell, so that the adjacent hollow holes form the vertical beams. Adjacent vertical beams are fixed with horizontal beams which span the hollow holes between the adjacent vertical beams.

2. The six-axis force sensor of claim 1, wherein, The positions of the adjacent horizontal beams are staggered.

3. The six-axis force sensor of claim 2, wherein, The adjacent horizontal beams are arranged above and below the strain gauges on the vertical beams.

4. The six-axis force sensor of claim 3, wherein, The thickness of the horizontal beam is greater than that of the vertical beam, and the part of the horizontal beam which is greater than the thickness of the vertical beam protrudes into the interior of the elastic carrier.

5. The six-axis force sensor of claim 4, wherein, Half-circular grooves are symmetrically formed on the side of the vertical beam, and the horizontal beam is arranged above the upper half-circular groove or below the lower half-circular groove.

6. The six-axis force sensor of claim 5, wherein, The length direction of the grid wire of the strain gauge is arranged at an angle of 30-60 degrees with the tangential direction of the end surface of the vertical beam.

7. The six-axis force sensor according to any one of claims 1 to 6, characterized in that The length direction of the grid wire of the strain gauge on any two adjacent vertical beams is consistent, and the strain gauges on the two vertical beams form a Wheatstone bridge, which is a full bridge or a half bridge.

8. The six-axis force sensor of claim 7, wherein, A loading platform is fixedly arranged at the top end of the elastic carrier, and a fixed platform is fixedly arranged at the bottom end of the elastic carrier.

9. The six-axis force sensor according to any one of claims 1 to 6, characterized in that A through hole is formed in the center of the loading platform and the fixed platform, and a plurality of connecting holes are uniformly arranged around the through hole of each of the loading platform and the fixed platform.

10. The six-axis force sensor of claim 9, wherein, The application relates to a six-dimensional force sensor.

11. A calibration device, characterized by The loading plate is arranged below the fixed plate, and the six-dimensional force sensor according to any one of claims 1-8 is fixedly arranged between the loading plate and the fixed plate. The application relates to a six-dimensional force sensor. The loading plate is arranged below the fixed plate, and the six-dimensional force sensor according to any one of claims 9-10 is fixedly arranged between the loading plate and the fixed plate.

12. A calibration device, characterized by The fixed plate and the loading platform are fixedly connected, and the loading plate and the fixed platform are fixedly connected. ​ ​ 13. The calibration device of claim 12, wherein, ​

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