Orthogonal equal-range six-dimensional force sensor

Abstract

The invention relates to the technical field of six-dimensional force sensors, in particular to an orthogonal equal-range six-dimensional force sensor. According to the technical scheme, the device comprises a mounting base, a first flexible hinge, a second flexible hinge and a force measuring connector, the two sides of the force measuring connector are jointly connected with the mounting base through the second flexible hinge and the first flexible hinge in sequence, and the second flexible hinge is vertically connected to the middle of the first flexible hinge; and two groups of second flexible hinges are arranged on each of the two sides of the force measuring joint and are arranged in parallel, so that the six-dimensional force sensor has a double-shaft parallel structure when being stressed in any direction. According to the II-shaped beam type six-dimensional force sensor, the internal beams of an I-shaped beam structure are changed into two parallel internal beams, a new patch scheme is provided, the problem of force measurement jump of the I-shaped beam type six-dimensional force sensor is solved, meanwhile, the torsional rigidity and the measurement precision are improved, and the purpose of equal-range measurement is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of six-dimensional force sensors, and in particular to an orthogonal equal-range six-dimensional force sensor. Background Art

[0002] Six-dimensional force sensors are widely used in the field of robotics for human-machine interaction, drag teaching, flexible assembly, etc. Among many flexible hinge sensors, there are common technical defects such as complex structure, large coupling degree, difficult calibration, and high cost.

[0003] The prior art proposed a weakly coupled flexible hinge six-dimensional force sensor with application number CN2024207164891, which adopts an I-shaped flexible hinge structure, can realize first-order bending to measure axial force, second-order bending to measure torque, and a bridge to measure the force in six degrees of freedom, thus realizing orthogonal measurement.

[0004] However, three major problems emerged during the implementation process:

[0005] 1) One side of the I-beam has two flexible hinges in parallel (corresponding to the first flexible hinge in the present invention), and the other side has only one flexible hinge (corresponding to the second flexible hinge in the present invention), which cannot meet the requirements of equal range measurement;

[0006] 2) The torsional stiffness around the internal beam axis is low, resulting in a low bending frequency in this direction, which can easily cause vibration and make the operation unstable.

[0007] 3) The biggest drawback is that when measuring the Z-axis force, the bending deformation of the internal beam also causes the torsion of the side beam when the force is transmitted to the Fz bridge on the side through the internal beam, affecting the measurement accuracy of Fz. In particular, when the sensor posture changes, the torsion direction of the measured Fz changes, which in turn causes the jump of the Fz measurement signal, making it impossible to achieve accurate measurement, such as Figure 1 ,exist Figure 1 The upper middle figure shows the theoretical value, and the lower figure shows the measured voltage value at different Fz positions. Summary of the invention

[0008] The purpose of the present invention is to propose an orthogonal equal-range six-dimensional force sensor in view of the problems pointed out in the background technology, such as the existence of jumps, the inability to meet the requirements of equal range, and the easy vibration.

[0009] The technical solution of the present invention: an orthogonal equal-range six-axis force sensor, comprising a mounting base, a first flexible hinge, a second flexible hinge and a force measuring joint, wherein both sides of the force measuring joint are connected to the mounting base through the second flexible hinge and the first flexible hinge in sequence, wherein the second flexible hinge is vertically connected to the middle of the first flexible hinge, and two groups of the second flexible hinges are arranged on both sides of the force measuring joint, and are arranged parallel to each other, so that the six-axis force sensor has a dual-axis parallel structure when subjected to force in any direction, thereby achieving the purpose of equal-range measurement and increased torsional stiffness.

[0010] Optionally, a II-shaped structure is formed between the force measuring joint and the first flexible hinge and the second flexible hinge on both sides.

[0011] Optionally, first strain gauges are installed on the front and rear sides and the side away from each other of the two groups of the second flexible hinges;

[0012] Second strain gauges are installed on both the upper and lower surfaces of the first flexible hinge;

[0013] A third strain gauge is installed on the front and rear sides of at least one group of first flexible hinges.

[0014] Optionally, the third strain gauges are installed on both sides of the front and rear sides of only one group of the first flexible hinges, and the Fz direction measurement of the other group of the first flexible hinges is transferred to one group of the second flexible hinges.

[0015] Optionally, third strain gauges are respectively installed on both sides of the front and rear sides of the two groups of the first flexible hinges, so that the six-axis force sensor forms a redundant structure to improve measurement accuracy.

[0016] Optionally, the mounting seat is a circular or polygonal hollow structure, and two groups of first flexible hinges are installed in parallel on the inner wall of the mounting seat.

[0017] Compared with the prior art, this application has the following beneficial technical effects:

[0018] This application proposes a new flexible hinge structure with two parallel flexible hinges in the middle, which transfers the Fz bridge to the upper and lower surfaces of one set of second flexible hinges, solving the problem of force jump in the six-dimensional force sensor of the I-beam.

[0019] Furthermore, the double second flexible hinge structure enables the six-axis force sensor to be a double-beam parallel structure regardless of the direction in which the force is applied, and it is easy to achieve the requirement of equal range measurement;

[0020] Furthermore, the parallel connection of the dual second flexible hinges in the middle greatly increases the torsional rigidity and solves the vibration problem;

[0021] In addition, through a flexibly selectable patch method, under the technical premise of solving the above-mentioned jump, increasing torsional stiffness, and realizing equal-range measurement, an additional bridge can be added to the first flexible hinge on one of the sides, which can be used for redundant design and improve the measurement accuracy of the six-dimensional force sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A comparison diagram of measured voltage values ​​in the presence of a jump in the prior art (top - applied Fz theoretical value; bottom - Fz measured voltage values ​​at different positions);

[0023] Figure 2 It is a stereogram of an orthogonal equal-range six-dimensional force sensor of the present invention that illustrates the Fz conversion relationship in an unmounted state;

[0024] Figure 3 It is a three-dimensional schematic diagram of an incomplete patch of the first flexible hinge in the present invention (the original bending bridge around the axis of the first flexible hinge is not patched);

[0025] Figure 4 for Figure 3 The main view of

[0026] Figure 5 It is a three-dimensional schematic diagram of a first flexible hinge complete patch in the present invention;

[0027] Figure 6 for Figure 5 The main view of

[0028] Figure 7 It is a comparison chart of the theoretical value and measured value of Fz of the orthogonal equal-range six-dimensional force sensor in the present invention.

[0029] Figure numerals: 1. mounting block; 2. first flexible hinge; 3. second flexible hinge; 4. force measuring joint; 5. first strain gauge; 6. second strain gauge; 7. third strain gauge. DETAILED DESCRIPTION

[0030] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0031] The components of the embodiments of the present invention generally described and shown in the drawings herein may be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention.

[0032] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without making any creative work shall fall within the scope of protection of the present invention.

[0033] In the description of the present invention, it should be noted that the terms "upper", "lower", "inner", "outer", "front end", "rear end", "two ends", "one end", "the other end" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0034] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0035] Embodiment 1, as Figure 2-Figure 4 As shown, the orthogonal equal-range six-dimensional force sensor proposed in the present invention adopts an incomplete patch method, including a mounting seat 1, a first flexible hinge 2, a second flexible hinge 3 and a force measuring joint 4, the two sides of the force measuring joint 4 are respectively connected to the mounting seat 1 through the second flexible hinge 3 and the first flexible hinge 2 in sequence, the second flexible hinge 3 is vertically connected to the middle of the first flexible hinge 2, the mounting seat 1 is a circular or polygonal hollow structure, the first flexible hinge 2, the second flexible hinge 3 and the force measuring joint 4 are all installed inside it, and the outside is used to fix the sensor base. Specifically, the second flexible hinge 3 is symmetrically connected to the two sides of the force measuring joint 4, that is, one end of the second flexible hinge 3 is fixed to the force measuring joint 4, and the other end is fixed to the middle side of the first flexible hinge 2, and the two ends of the first flexible hinge 2 are fixed to the inner wall of the mounting seat 1. The internal components of the mounting base 1, namely the force measuring joint 4, form a II-shaped structure with the first flexible hinge 2 and the second flexible hinge 3 on both sides. The first flexible hinge 2, the second flexible hinge 3 and the direction perpendicular to the force measuring joint 4 are in an orthogonal relationship.

[0036] In this embodiment, two groups of the second flexible hinges 3 are arranged on both sides of the force measuring joint 4 and are arranged parallel to each other, so that the six-axis force sensor has a dual-axis parallel structure when subjected to force in any direction, achieving the purpose of equal range measurement and increasing torsional stiffness. Figure 2The figure shows the position change relationship between Fz (original) in the prior art and Fz (current) in the six-axis force sensor of the present application, and the Fz bridge (the bent bridge around the axis of the first flexible hinge in the prior art) is transferred to the upper and lower surfaces of one of the internal sets of the second flexible hinges 3, thereby solving the problem of force jump in the six-axis force sensor of the I-beam in the prior art.

[0037] The positions of My and Fz corresponding to the two sets of second flexible hinges 3 can be interchanged.

[0038] Furthermore, the first strain gauges 5 are installed on the front and rear sides and the side away from each other of the two groups of second flexible hinges 3, which changes the strain gauges on the original two sides of the middle beam to the outside of the two beams, avoiding the problem that the space between the internal double second flexible hinges 3 is too small to be patched. The second strain gauges 6 are installed on both the upper and lower surfaces of the first flexible hinge 2, and only the third strain gauges 7 are installed on both sides of the front and rear sides of one group of the first flexible hinges 2. The front and rear sides of the other group of the first flexible hinges 2 are not patched, so that the measurement of the Fz direction of the first flexible hinge 2 can be transferred to the group of second flexible hinges 3 in the middle to avoid jumps.

[0039] In this six-dimensional force sensor, there are a total of six groups of strain gauges, each group of which forms a full-bridge strain gauge in two directions: front and back, left and right, or up and down. That is, each beam has two or four strain gauges (the optimal is four), with no redundant degrees of freedom. The double second flexible hinges in the middle are connected in parallel, which greatly increases the torsional stiffness and solves the vibration problem.

[0040] Example 2, see Figure 5 , Figure 6 On the basis of Example 1, the orthogonal equal-range six-axis force sensor proposed in the present invention adopts a full patch method, and a third strain gauge 7 is respectively installed on both sides of the front and rear sides of the two groups of first flexible hinges 2, which is equivalent to adding an additional bridge on the first flexible hinge, so that the six-axis force sensor of the present invention forms a redundant structure and improves the measurement accuracy.

[0041] The present invention combines the strain gauge patch solution, such as Figure 7 It can be seen that the Fz measurement value measured by the six-dimensional force sensor is basically consistent with the theoretical value under the same conditions and will not jump.

[0042] Therefore, whether it is the first embodiment or the second embodiment, starting from the structure of the six-dimensional force sensor, it is designed as a II-beam type six-dimensional force sensor, and one internal beam (i.e., the second flexible hinge 3) is changed into two parallel ones, and a new patch scheme is proposed to complete the equal range design and reduce vibration and other issues, reduce inter-dimensional coupling, reduce calibration time, and be more practical. At the same time, the most important thing is to transfer the Fz bridge (the original curved bridge around the axis of the first flexible hinge 2 on the side) to the upper and lower surfaces of the internal beam (one of the second flexible hinges 3), which solves the problem of Fz jumping when the sensor changes.

[0043] The above specific embodiments are merely preferred embodiments of the present invention. Based on the technical solutions of the present invention and the relevant inspirations of the above embodiments, those skilled in the art may make various alternative improvements and combinations to the above specific embodiments. The above specific embodiments are merely explanations of the present invention, and are not limitations of the present invention.

Claims

1. An orthogonal equal-range six-dimensional force sensor, comprising a mounting seat (1), a first flexible hinge (2), a second flexible hinge (3) and a force measuring joint (4), wherein both sides of the force measuring joint (4) are connected to the mounting seat (1) through the second flexible hinge (3) and the first flexible hinge (2) in sequence, wherein the second flexible hinge (3) is vertically connected to the middle of the first flexible hinge (2), characterized in that: The second flexible hinges (3) are arranged in two groups on both sides of the force measuring joint (4) and are arranged parallel to each other, so that the six-dimensional force sensor has a dual-axis parallel structure when subjected to force in any direction, thereby achieving the purpose of equal range measurement and increasing torsional stiffness.

2. The orthogonal equal-range six-dimensional force sensor according to claim 1, characterized in that: A II-shaped structure is formed between the force measuring joint (4) and the first flexible hinge (2) and the second flexible hinge (3) on both sides.

3. The orthogonal equal-range six-dimensional force sensor according to claim 2, characterized in that: The front and rear sides and the side away from each other of the two groups of the second flexible hinges (3) are all installed with first strain gauges (5); Second strain gauges (6) are installed on both the upper and lower surfaces of the first flexible hinge (2); A third strain gauge (7) is installed on the front and rear sides of at least one group of first flexible hinges (2).

4. The orthogonal equal-range six-dimensional force sensor according to claim 3, characterized in that: Only one group of the first flexible hinges (2) is provided with a third strain gauge (7) on both sides of the front and rear sides, and the Fz direction measurement of the other group of the first flexible hinges (2) is transferred to one group of the second flexible hinges (3).

5. The orthogonal equal-range six-dimensional force sensor according to claim 3, characterized in that: Third strain gauges (7) are respectively installed on both sides of the front and rear sides of the two groups of the first flexible hinges (2), so that the six-dimensional force sensor forms a redundant structure, thereby improving the measurement accuracy.

6. The orthogonal equal-range six-dimensional force sensor according to claim 1, characterized in that: The mounting seat (1) is a circular or polygonal hollow structure, and two groups of first flexible hinges (2) are mounted in parallel on the inner wall of the mounting seat (1).

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