Integrated flexible branch type six-dimensional force sensor structure based on Stewart mechanism

Abstract

The utility model relates to the technical field of sensors, and discloses an integrated compliant branch type six-dimensional force sensor structure based on a Stewart mechanism, a sensor body structure comprises an upper force transmission platform, six compliant branch mechanisms and a lower force transmission platform, the six compliant branch mechanisms are uniformly connected to the upper force transmission platform and the lower force transmission platform according to a specific angle, the flexible branch mechanism comprises a flexible structure I, a flexible structure II and a flexible connecting piece, is an equivalent two-force rod formed by five rotational degrees of freedom and one translational degree of freedom, and meets the characteristic requirements of a two-force rod branch of a Stewart six-dimensional force sensor; according to the utility model, on the basis that the characteristics of easy solution of a force mapping relation and flexible structure of the assembly type Stewart six-dimensional force sensor are maintained, the problems of high assembly difficulty, insufficient structure bearing, time and labor waste, zero crossing, hysteresis and the like of the conventional assembly type Stewart six-dimensional force sensor are solved, and the engineering practicability of the Stewart six-dimensional force sensor is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of sensors, in particular to an integrated compliant branch-type six-dimensional force sensor structure based on a Stewart mechanism. Background Art

[0002] The Stewart platform mechanism was first proposed by American scholar Stewart in 1965 as a flight simulator mechanism. Subsequently, Australian scholar Hunt proposed the application of the Stewart platform to industrial robots in 1978, forming a new type of parallel robot with 6 degrees of freedom. Since then, this mechanism has been successfully applied to various fields, such as high-power assembly robots, walking robots, robot wrists, etc.

[0003] Strain-type six-axis force sensors are widely used in the measurement of spatial force systems (including force components in three directions and moment components in three directions) due to their mature technology. The structures of strain-type six-axis force sensors in service are mainly integrated cross-beam structures and assembled Stewart parallel structures. Compared with the integrated cross-beam structure, the assembled Stewart parallel structure has the advantages of easy solution of force mapping relationship and strong bearing capacity.

[0004] However, due to the limitations of assembly technology in the existing technology, Stewart six-axis force sensors generally have problems such as zero crossing, nonlinearity, hysteresis, etc. caused by assembly gap and assembly error, which seriously restricts the engineering application of Stewart six-axis force sensors.

[0005] In view of the above problems, the utility model proposes an integrated compliant branch-type six-dimensional force sensor structure based on the Stewart mechanism to solve the problems existing in the above-mentioned prior art. Utility Model Content

[0006] 1. Technical issues to be resolved

[0007] In view of the shortcomings of the prior art, the utility model provides an integrated flexible branch-type six-axis force sensor structure based on the Stewart mechanism, aiming to improve the zero crossing, nonlinearity and difficulty of assembly caused by the use of the Stewart six-axis force sensor in the prior art, which restricts the engineering application of the Stewart six-axis force sensor.

[0008] (II) Technical solution

[0009] In order to achieve the above-mentioned purpose of improving the engineering practicality of the Stewart six-axis force sensor, the utility model provides the following technical solutions:

[0010] An integrated compliant branch-type six-dimensional force sensor structure based on a Stewart mechanism, characterized in that it includes: an upload force platform; a lower force transmission platform, arranged below the upload force platform; a plurality of compliant branch mechanisms, arranged between the upload force platform and the lower force transmission platform, including an upload force platform connecting seat, a lower force transmission platform connecting seat, a flexible structure one, a flexible connector and a flexible structure two, one end of the upload force platform connecting seat is connected to the upload force platform, and the other end is connected to the flexible structure one, the flexible structure two is arranged on a side of the flexible structure one away from the upload force platform connecting seat, the flexible connector is arranged at a lower end of the flexible structure two away from the flexible structure, and is connected to the lower force transmission platform connecting seat, and the lower force transmission platform connecting seat is arranged on the lower force transmission platform.

[0011] Based on the above technical features: when in use, the multiple flexible branch mechanisms are evenly connected between the upper force transmission platform and the lower force transmission platform at a specific angle, which can greatly improve the bearing capacity of the structure; at the same time, when the upper force transmission platform is subjected to force, the force is transmitted to the upper force transmission platform connecting seat through the upper force transmission platform, and then transmitted to the flexible structures 1 on both sides through the upper force transmission platform connecting seat, and then transmitted to the flexible structure 2 and the flexible connector in turn through the flexible structure 1, and finally transmitted to the lower force transmission platform through the lower force transmission platform connecting seat.

[0012] As a preferred solution of the integrated compliant branch type six-dimensional force sensor structure based on the Stewart mechanism described in the utility model:

[0013] The flexible structure 1 is a herringbone structure, including an H-shaped workpiece, which is arranged at the lower end of the upper force transmission platform connecting seat; an I-shaped workpiece, which is arranged at the lower end of the H-shaped workpiece and connected to the upper end of the flexible structure 2; the rotation axes of the H-shaped workpiece and the I-shaped workpiece are perpendicular to each other.

[0014] Based on the above technical features: through the above structural design, it is used to provide the flexible branch mechanism with two mutually perpendicular axes of rotational freedom.

[0015] As a preferred solution of the integrated compliant branch type six-dimensional force sensor structure based on the Stewart mechanism described in the utility model:

[0016] The second flexible structure comprises a return-shaped piece arranged between the I-shaped workpiece and the flexible connecting piece, a circuit board is arranged on one side of the return-shaped piece, and a connector is connected to the surface of the circuit board.

[0017] Based on the above technical features: a circuit board connected to the connector is provided on the flexible structure 2, which is convenient for connection and use.

[0018] As a preferred solution of the integrated compliant branch type six-dimensional force sensor structure based on the Stewart mechanism described in the utility model:

[0019] The cross section of the return-shaped piece is in the shape of a Chinese character U, and an opening groove is formed on a side of the return-shaped piece away from the circuit board.

[0020] Based on the above technical features: it is used to provide a translational freedom in a direction perpendicular to the branch axis for the force transmission platform under the flexible branch mechanism.

[0021] As a preferred solution of the integrated compliant branch type six-dimensional force sensor structure based on the Stewart mechanism described in the utility model:

[0022] The flexible connector is a prism structure having three mutually perpendicular and colinear rotation axes, and one end of the flexible connector is connected to the second flexible structure.

[0023] Based on the above technical features: the flexible connector can provide the flexible branch mechanism with three rotational degrees of freedom similar to a ball joint, one end of the flexible connector is connected to the flexible structure 2, providing the flexible branch mechanism with three rotational degrees of freedom similar to a ball joint; the flexible structure 1, the flexible connector and the flexible structure 2 cooperate to make the flexible branch mechanism an equivalent two-force rod with five rotational degrees of freedom plus one translational degree of freedom.

[0024] As a preferred solution of the integrated compliant branch type six-dimensional force sensor structure based on the Stewart mechanism described in the utility model:

[0025] Two groups of sensitive strain gauges are fixedly connected to the inner wall of the return-shaped member, and the two groups of sensitive strain gauges are symmetrically distributed along the central axis of the inner bottom wall of the return-shaped member.

[0026] Based on the above technical features: two sets of sensitive strain gauges with symmetrical positions and equal resistance values ​​(R1=R2=R3=R4) are pasted on the area with the largest deformation on the inner surface of the second flexible structure. The four sensitive strain gauges are connected in sequence and welded to the circuit board to form a dual differential full-bridge circuit.

[0027] As a preferred solution of the integrated compliant branch type six-dimensional force sensor structure based on the Stewart mechanism described in the utility model:

[0028] A plurality of force application holes and two coordinate system positioning holes are provided at the upper end of the upper force transmission platform, and the plurality of force application holes are distributed in a ring shape along the inner wall of the upper force transmission platform; a mounting hole is provided at the lower end of the lower force transmission platform.

[0029] Based on the above technical features: it is convenient to connect other components and install sensors.

[0030] (III) Beneficial effects

[0031] Compared with the prior art, the utility model provides an integrated flexible branch-type six-dimensional force sensor structure based on the Stewart mechanism, which has the following beneficial effects:

[0032] 1. In the utility model, the sensor structure includes an upper force transmission platform, six flexible branches and a lower force transmission platform, which can be formed by integrated wire cutting. The structure has good processing performance and overcomes the problems of high assembly difficulty, time-consuming and labor-intensive, zero crossing and hysteresis of the assembled Stewart six-axis force sensor, thereby improving the engineering practicality of the Stewart six-axis force sensor.

[0033] 2. The utility model meets the requirements of the two-force-rod branch characteristics of the Stewart six-dimensional force sensor, that is, an integrated flexible branch-type six-dimensional force sensor structure based on the Stewart mechanism has the characteristics of easy solution of the force mapping relationship and flexible structure. The flexible structure one, the flexible structure two and the flexible connector in the flexible branch mechanism do not use structures that are prone to stress concentration, which greatly improves the bearing capacity of the structure; it solves the problems of zero crossing, nonlinearity and difficulty in assembly caused by assembly in the use of the Stewart six-dimensional force sensor in the prior art in the background technology, which restricts the engineering application of the Stewart six-dimensional force sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a structural schematic diagram of an integrated compliant branch-type six-dimensional force sensor based on the Stewart mechanism of the utility model;

[0035] Figure 2 A schematic diagram of the structure of a compliant branch mechanism of an integrated compliant branch type six-dimensional force sensor based on a Stewart mechanism of the utility model;

[0036] Figure 3 A schematic diagram of the position of the flexible structure of the integrated compliant branch type six-dimensional force sensor based on the Stewart mechanism of the utility model;

[0037] Figure 4 It is a schematic diagram of the partial structure of the compliant branch mechanism of the integrated compliant branch type six-dimensional force sensor based on the Stewart mechanism of the utility model;

[0038] Figure 5 It is a schematic diagram of the second structure of the flexible structure of the integrated compliant branch type six-dimensional force sensor based on the Stewart mechanism of the utility model.

[0039] in:

[0040] 1. Upper force transmission platform; 11. Coordinate system positioning hole; 12. Force application hole; 2. Lower force transmission platform; 21. Mounting hole; 3. Flexible branch mechanism; 31. Upper force transmission platform connection seat; 32. Lower force transmission platform connection seat; 33. Flexible structure 1; 331. H-shaped workpiece; 332. I-shaped workpiece; 34. Flexible connector; 35. Flexible structure 2; 351. Retractable part; 352. Open slot; 353. Sensitive strain gauge; 354. Circuit board; 355. Connector. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0042] Example 1: Please refer to Figure 1-5 As shown, the utility model provides a technical solution:

[0043] An integrated compliant branch-type six-dimensional force sensor structure based on a Stewart mechanism, comprising:

[0044] An upper force transmission platform 1 and a lower force transmission platform 2, wherein the upper force transmission platform 1 is located above the lower force transmission platform 2, a plurality of force application holes 12 and two coordinate system positioning holes 11 are provided at the upper end of the upper force transmission platform 1, and the plurality of force application holes 12 are distributed in a ring shape along the inner wall of the upper force transmission platform 1, and a mounting hole 21 is provided at the lower end of the lower force transmission platform 2;

[0045] A plurality of flexible branch mechanisms 3, wherein the flexible branch mechanisms 3 are fixedly installed between the upper force transmission platform 1 and the lower force transmission platform 2;

[0046] Specifically, when in use, the plurality of flexible branch mechanisms 3 are evenly connected between the upper force transmission platform 1 and the lower force transmission platform 2 at specific angles without using a structure that is prone to generate stress concentration, thereby improving the bearing capacity of the structure.

[0047] As a preferred embodiment, Figure 1 As shown, the force-transmitting platform 1 has eight evenly distributed force-applying holes 12 and two coordinate system positioning holes 11;

[0048] Specifically, when in use, the external force / torque acts on the upper force transmission platform 1 through the force application hole 12, which can effectively ensure the uniformity of force transmission.

[0049] Example 2: Reference Figure 1-Figure 5As shown, the compliant branch mechanism 3 includes an upper force transmission platform connection seat 31, a lower force transmission platform connection seat 32, a flexible structure 1 33, a flexible connector 34 and a flexible structure 2 35; wherein the upper force transmission platform connection seat 31 is a herringbone structure, and one end of the upper force transmission platform connection seat 31 is connected to the upper force transmission platform 1, and the other end is connected to the flexible structure 1 33; the flexible structure 2 35 is arranged on a side of the flexible structure 1 33 away from the upper force transmission platform connection seat 31; the flexible connector 34 is arranged at the lower end of the flexible structure 2 35 away from the flexible structure 1 33, and is connected to the lower force transmission platform connection seat 32, and the lower force transmission platform connection seat 32 is fixedly arranged on the lower force transmission platform 2;

[0050] Specifically, during use, when the upper force transmission platform 1 is subjected to force, the force is transmitted to the upper force transmission platform connecting seat 31 via the upper force transmission platform 1, and then transmitted to the flexible structures 1 33 on both sides via the upper force transmission platform connecting seat 31, and then transmitted to the flexible structure 2 35 and the flexible connector 34 in turn via the flexible structure 1 33, and finally transmitted to the lower force transmission platform 2 via the lower force transmission platform connecting seat 32.

[0051] As a preferred embodiment, Figure 4 As shown, the flexible structure 1 33 includes an H-shaped workpiece 331 and an I-shaped workpiece 332; wherein the H-shaped workpiece 331 is fixedly connected to the lower end of the force-transmitting platform connecting seat 31; the I-shaped workpiece 332 is fixedly connected to the lower end of the H-shaped workpiece 331, and the I-shaped workpiece 332 is fixedly connected to the upper end of the flexible structure 2 35; the one H-shaped workpiece 331 and the one I-shaped workpiece 332 are connected in series, and the rotation axes of the H-shaped workpiece 331 and the I-shaped workpiece 332 are perpendicular to each other, and the flexible structure 1 33 is formed by connecting the one H-shaped workpiece 331 and the one I-shaped workpiece 332;

[0052] Specifically, when in use, the above structural design is used to provide the flexible branch mechanism 3 with two rotational degrees of freedom with axes perpendicular to each other.

[0053] As a preferred embodiment, Figure 4 As shown, the flexible connector 34 is a prismatic structure with three mutually perpendicular and colinear rotation axes, which can provide the flexible branch mechanism 3 with three rotational degrees of freedom similar to a ball joint. One end of the flexible connector 34 is connected to the flexible structure 2 35, providing the flexible branch mechanism 3 with three rotational degrees of freedom similar to a ball joint. The flexible structure 1 33, the flexible connector 34 and the flexible structure 2 35 cooperate to make the flexible branch mechanism 3 an equivalent two-force rod with five rotational degrees of freedom and one translational degree of freedom.

[0054] As a preferred embodiment, Figure 5As shown, the second flexible structure 35 includes a return-shaped member 351, the return-shaped member 351 is fixedly connected between the H-shaped workpiece 331 and the flexible connecting member 34, and a circuit board 354 is fixedly connected to one side of the return-shaped member 351, a connector 355 is connected to the surface of the circuit board 354, and an open groove 352 is provided at one end of the second flexible structure 35, and one end of the second flexible structure 35 provided with the open groove 352 is connected to one end of the I-shaped workpiece 332;

[0055] Specifically, when in use, the U-shaped structural design of the second flexible structure 35 is used to provide the flexible branch mechanism 3 with a degree of freedom of translation in a direction perpendicular to the branch axis.

[0056] As a preferred embodiment, Figure 1 , Figure 2 and Figure 4 As shown, the flexible connector 34 is a prismatic structure with three mutually perpendicular and colinear rotation axes, and one end of the flexible connector 34 is connected to the flexible structure 2 35, for providing the flexible branch mechanism 3 with three rotational degrees of freedom similar to a ball joint; one end of the flexible connector 34 is connected to the flexible structure 2 35, and the other end is connected to the lower force transmission platform 2; the lower force transmission platform 2 is a hollow hexagonal column structure, and eight mounting holes 21 are evenly distributed on the lower end surface of the lower force transmission platform 2 for sensor installation.

[0057] As a preferred embodiment, Figure 5 As shown, the flexible structure 2 35 is provided with a circuit board 354 connected to the connector 355, and four sensitive strain gauges 353 with symmetrical positions and equal resistance values ​​are pasted on the maximum deformation area of ​​the inner surface of the flexible structure 2 35. The four sensitive strain gauges 353 are connected in sequence and welded with the circuit board 354 to form a dual differential full-bridge circuit.

[0058] The integrated compliant branch-type six-dimensional force sensor structure based on the Stewart mechanism of the utility model is used during:

[0059] The compliant branch mechanism 3 includes an upper force transmission platform connecting seat 31, a flexible structure 1 33, a flexible structure 2 35, a flexible connector 34 and a lower force transmission platform connecting seat 32, and branches into an equivalent two-force rod consisting of five rotational degrees of freedom and one translational degree of freedom, which meets the requirements of the two-force rod branch characteristics of the Stewart six-axis force sensor, that is, an integrated compliant branch type six-axis force sensor structure based on the Stewart mechanism has the characteristics of easy solution of force mapping relationship and flexible structure. At the same time, the flexible structure 1 33, the flexible structure 2 35 and the flexible connector 34 in the compliant branch mechanism 3 do not use stress concentration structures, which greatly improves the bearing capacity of the structure. Through the upper force transmission platform 1, multiple compliant branch mechanisms 3 and the lower force transmission platform 2, it can be formed by integrated wire cutting. The structure has good processing performance and overcomes the problems of high assembly difficulty, time-consuming and labor-intensive, zero crossing and hysteresis of the assembled Stewart six-axis force sensor, thereby improving the engineering practicality of the Stewart six-axis force sensor.

[0060] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0061] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An integrated compliant branch-type six-dimensional force sensor structure based on a Stewart mechanism, characterized in that: include: Upload force platform (1); A lower force transmission platform (2) is arranged below the upper force transmission platform (1); A plurality of flexible branch mechanisms (3) are arranged between an upper force transmission platform (1) and a lower force transmission platform (2), and include an upper force transmission platform connection seat (31), a lower force transmission platform connection seat (32), a flexible structure 1 (33), a flexible connecting member (34) and a flexible structure 2 (35); one end of the upper force transmission platform connection seat (31) is connected to the upper force transmission platform (1), and the other end is connected to the flexible structure 1 (33); the flexible structure 2 (35) is arranged on a side of the flexible structure 1 (33) away from the upper force transmission platform connection seat (31); the flexible connecting member (34) is arranged at a lower end of the flexible structure 2 (35) away from the flexible structure 1 (33) and connected to the lower force transmission platform connection seat (32); and the lower force transmission platform connection seat (32) is arranged on the lower force transmission platform (2).

2. The one-piece compliant branch-type six-dimensional force sensor structure based on the Stewart mechanism as claimed in claim 1, characterized in that: The flexible structure (33) is a herringbone structure, comprising An H-shaped workpiece (331) is disposed at the lower end of the force-transmitting platform connecting seat (31); The I-shaped workpiece (332) is disposed at the lower end of the H-shaped workpiece (331) and is connected to the upper end of the second flexible structure (35).

3. The one-piece compliant branch-type six-dimensional force sensor structure based on the Stewart mechanism as claimed in claim 2, characterized in that: The rotation axes of the H-shaped workpiece (331) and the I-shaped workpiece (332) are perpendicular to each other.

4. The one-piece compliant branch-type six-dimensional force sensor structure based on the Stewart mechanism as claimed in claim 1, characterized in that: The second flexible structure (35) comprises a return-shaped member (351) arranged between the I-shaped workpiece (332) and the flexible connecting member (34), a circuit board (354) being arranged on one side of the return-shaped member (351), and a connector (355) being connected to the surface of the circuit board (354).

5. The one-piece compliant branch-type six-dimensional force sensor structure based on the Stewart mechanism as claimed in claim 4, characterized in that: The cross section of the return-shaped member (351) is in the shape of a Chinese character "Yu", and an opening groove (352) is provided on a side of the return-shaped member (351) away from the circuit board (354).

6. The one-piece compliant branch-type six-dimensional force sensor structure based on the Stewart mechanism as claimed in claim 4, characterized in that: Two groups of sensitive strain gauges (353) are arranged in the return-shaped member (351), and the two groups of sensitive strain gauges (353) are symmetrically distributed along the central axis of the inner bottom wall of the return-shaped member (351).

7. The one-piece compliant branch-type six-dimensional force sensor structure based on the Stewart mechanism as claimed in claim 1, characterized in that: The flexible connecting member (34) is a prism structure having three mutually perpendicular and colinear rotation axes, and one end of the flexible connecting member (34) is connected to the second flexible structure (35).

8. The one-piece compliant branch-type six-dimensional force sensor structure based on the Stewart mechanism as claimed in claim 1, characterized in that: A plurality of force application holes (12) and two coordinate system positioning holes (11) are provided at the upper end of the force application platform (1), and the plurality of force application holes (12) are distributed in a ring shape along the inner wall of the force application platform (1).

9. The one-piece compliant branch-type six-dimensional force sensor structure based on the Stewart mechanism as claimed in claim 1, characterized in that: A mounting hole (21) is provided at the lower end of the lower force transmission platform (2).

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