Orthogonal equal-range six-dimensional force sensor
By adopting a parallel structure of dual flexible hinges in the middle and a flexible strain gauge patching method in the six-dimensional force sensor, the problems of equal range measurement and vibration are solved, and the measurement accuracy and stability are improved.
Patent Information
- Application Number
- CN202423089146.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-15
- Publication Date
- 2025-10-03
- Estimated Expiration
- 2034-12-15
AI Technical Summary
The existing six-dimensional force sensor cannot meet the requirements of equal range measurement, and its low torsional stiffness leads to inaccurate vibration and Fz measurement accuracy.
A parallel structure with two flexible hinges in the middle is adopted to transfer the Fz bridge to the upper and lower surfaces of the second flexible hinge. Through a dual-axis parallel design and flexible strain gauge patching, equal range measurement and increased torsional stiffness are achieved.
The six-dimensional force sensor can measure the same range when subjected to force in any direction, which reduces vibration and improves measurement accuracy and stability.
Smart Images
Figure CN223412863U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of six-dimensional force sensors, in particular to an orthogonal equal-range six-dimensional force sensor. Background Art
[0002] Six-dimensional force sensors are widely used in robotics for applications such as human-machine interaction, drag-based teaching, and flexible assembly. However, many flexible hinge sensors suffer from common technical drawbacks, including complex structures, high coupling, difficult calibration, and high costs.
[0003] 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 moment, and bridge to measure force in six degrees of freedom, thus realizing orthogonal measurement.
[0004] However, during the implementation process, three major problems arose:
[0005] 1) One side of the I-beam has two flexible hinges in parallel (corresponding to the first flexible hinge in the present invention), while 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 unstable operation.
[0007] 3) The biggest drawback is that when measuring the Z-axis force, the internal beam is bent and deformed when the force is transmitted to the Fz bridge on the side, which also causes the side beam to twist, affecting the Fz measurement accuracy. In particular, when the sensor posture changes, the twisting direction of the measured Fz changes, which in turn causes the Fz measurement signal to jump, 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. Utility Model Content
[0008] The purpose of the utility model is to propose an orthogonal equal-range six-dimensional force sensor in response to the problems of jumps, failure to meet the requirements of equal range, and easy vibration pointed out in the background art.
[0009] The technical solution of the present invention is: an orthogonal equal-range six-dimensional 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 in sequence through the second flexible hinge and the first flexible hinge, wherein the second flexible hinge is vertically connected to the middle part 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-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 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 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, 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 installed on both sides of the front and rear sides of the two groups of the first flexible hinges, respectively, so that the six-dimensional force sensor forms a redundant structure to improve measurement accuracy.
[0016] Optionally, the mounting seat is a circular or polygonal hollow structure, and the 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 have a double-beam parallel structure regardless of the direction of force, making it easy to achieve the requirement of equal range measurement;
[0020] Furthermore, the parallel connection of the dual second flexible hinges in the middle significantly increases the torsional stiffness and solves the vibration problem;
[0021] In addition, through the flexible 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 chart of measured voltage values in the presence of a jump in the prior art (top - applied Fz theoretical value; bottom - measured Fz voltage values at different positions);
[0023] Figure 2 This is a three-dimensional diagram of the orthogonal equal-range six-dimensional force sensor of the present invention in the unmounted state, illustrating the Fz conversion relationship;
[0024] Figure 3 Schematic diagram of the incomplete patch of the first flexible hinge in the present invention (the original curved bridge around the axis of the first flexible hinge is not patched);
[0025] Figure 4 for Figure 3 The main view;
[0026] Figure 5 This is a three-dimensional schematic diagram of a first flexible hinge fully patched in the present invention;
[0027] Figure 6 for Figure 5 The main view;
[0028] Figure 7 This is a comparison chart of the theoretical and measured values of Fz for the orthogonal equal-range six-dimensional force sensor in the present utility model.
[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 with reference to 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 a variety of 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 rather 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 this field without making any creative work shall fall within the scope of protection of the present invention.
[0033] In the description of this utility model, it should be noted that the terms "upper," "lower," "inner," "outer," "front end," "rear end," "both ends," "one end," "the other end," and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate the description of this utility model and simplify the description. They are not intended to indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on this utility model. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.
[0034] In the description of this utility model, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections; direct connections, indirect connections through an intermediate medium, and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on the specific circumstances.
[0035] Example 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 and includes a mounting base 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 base 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 base 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 both 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. The two ends of the first flexible hinge 2 are fixed to the inner wall of the mounting base 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, the second flexible hinge 3 is located on both sides of the force measuring joint 4, and two groups are arranged in parallel with 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 curved 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 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 groups of second flexible hinges 3 can be interchanged.
[0038] Furthermore, first strain gauges 5 are installed on the front and rear sides of both sets of second flexible hinges 3, as well as on the side facing away from each other. This relocates the strain gauges originally on both sides of the central beam to the outside of the two beams, avoiding the problem of insufficient space between the two internal second flexible hinges 3 for patching. Second strain gauges 6 are installed on both the top and bottom surfaces of the first flexible hinges 2. Only third strain gauges 7 are installed on the front and rear sides of one set of first flexible hinges 2, leaving the front and rear sides of the other set of first flexible hinges 2 unpaired. This allows the Fz direction measurement of this first flexible hinge 2 to be transferred to the central set of second flexible hinges 3, avoiding jumps.
[0039] This six-dimensional force sensor has 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 Based on the first embodiment, 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 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 utility model combines the strain gauge patch solution by 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 does not jump.
[0042] Therefore, both Example 1 and Example 2, starting from the structure of the six-dimensional force sensor, are designed as a II-beam six-dimensional force sensor. The internal beam (i.e., the second flexible hinge 3) is replaced with two parallel beams. A new patch solution is proposed to achieve equal range design and reduce vibration, reduce inter-dimensional coupling, shorten calibration time, and enhance practicality. Most importantly, the Fz bridge (originally a curved bridge around the axis of the first lateral flexible hinge 2) is transferred to the upper and lower surfaces of the internal beam (one of the second flexible hinges 3), resolving the issue 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 teachings of the above embodiments, those skilled in the art can 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 base (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 base (1) in sequence through the second flexible hinge (3) and the first flexible hinge (2), 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 located on both sides of the force measuring joint (4), with two groups arranged in parallel with 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 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).