CN104048790A - Dual orthogonal six-axis force sensor and measuring method - Google Patents

Abstract

The invention relates to a dual orthogonal six-axis force sensor and a measuring method. The dual orthogonal six-axis force sensor is a novel force decoupling and isotropic robot six-axis force sensor. The dual orthogonal six-axis force sensor comprises an upper platform, a lower platform, elastic connecting rods and an elastic beam. The six elastic connecting rods are equally divided into three groups, each group is mutually orthogonal, double-shaft elastic hinges are adopted respectively at two ends of each elastic connecting rod, one end of each elastic connecting rod is connected with the upper platform, the other end of each elastic connecting rod is connected with the lower platform through the elastic beam, and a T-shaped structure is formed. Compared with a traditional structure, the dual orthogonal six-axis force sensor is large in strain, simple in structure and good in decoupling effect and effectively solves the problem of contradiction between sensor rigidity and sensitivity.

Description

Dual Orthogonal Six-dimensional Force Sensor and Measurement Method

technical field

    The invention belongs to the field of industrial robots, in particular to a six-dimensional force sensor and a measuring method.

Background technique

   The six-dimensional force sensor is usually installed on the wrist of the robot hand to detect the force information of the robot hand and feed this information back to the control system, so as to realize the control of various motion states of the robot hand. As the sensing element, the elastic body determines the performance of the sensor to a certain extent, and is one of the core issues in the research of the six-dimensional force sensor. With the development of the field of industrial robots, various forms of six-dimensional force sensors have been developed at home and abroad, but there are some problems. For example: Although the Watson six-dimensional force sensor developed by the American DRAPER laboratory has the advantages of strong bearing capacity, good impact resistance, and simple structure, it also has disadvantages such as low sensitivity and large interference between forces in various directions; The six-dimensional force sensor solves the problem of large mutual interference between forces in various directions, but due to structural limitations, the contradiction between its stiffness and sensitivity is relatively large, and it is difficult to coordinate; a four-dimensional force sensor developed by Belgium's Brussel and Israel's Kroll at the same time The six-dimensional force sensor with the vertical rib structure is simple in structure, the coupling between dimensions is small, and the theoretical analysis is convenient, but the sensitivity in the vertical direction is low; in 1987, Yoshikawa, Uchiyama and Bayo in Japan analyzed the six-dimensional wrist force sensor with the Maltese cross structure. It is one of the most widely used sensors at present. The design of the sensor is convenient, the theoretical relationship is simple and easy to analyze, the inter-dimensional coupling is small, and it has high stiffness. However, due to the complex structure, it is difficult to process. Domestically, Huang Xinhan and others designed a six-dimensional wrist force sensor with a non-radial three-beam centrosymmetric structure; Zeng Qingzhao et al. studied a new type of wheel six-dimensional force sensor; Yuan Zhejun designed a six-dimensional force sensor with eight vertical ribs. For sensors, Hefei Institute of Intelligence, Chinese Academy of Sciences and China Textile University have successively developed cross-structure six-dimensional force sensors, etc., but the above-mentioned sensors have some problems in terms of structure, sensitivity, inter-dimensional coupling, and stiffness.

Contents of the invention

       Aiming at the deficiencies of the prior art, the invention provides a dual orthogonal six-dimensional force sensor and a measurement method.

In order to achieve the above goals, the present invention adopts the following technical solutions: 

A dual orthogonal six-dimensional force sensor is characterized in that it includes an upper platform, a lower platform, and six elastic connecting rods. Wherein, two elastic beams are respectively arranged on three surfaces of the lower platform. One end of the six elastic connecting rods is connected to the corresponding elastic beams, and the other ends are all connected to the platform to form a T-shaped structure.

According to the aforementioned dual orthogonal six-dimensional force sensor, it is characterized in that the upper platform is provided with a round hole for connecting the model; the three surfaces of the lower platform are perpendicular to each other according to the OXYZ coordinate system. the

According to the aforementioned dual orthogonal six-dimensional force sensor, it is characterized in that six elastic connecting rods are arranged in groups of two and arranged along the directions of X, Y, and Z axes respectively. the

According to the aforementioned dual orthogonal six-dimensional force sensor, it is characterized in that the planes formed by the axes of two elastic connecting rods in each group are perpendicular to each other. the

According to the aforementioned dual orthogonal six-dimensional force sensor, it is characterized in that a biaxial elastic hinge is arranged at both ends of each elastic connecting rod. the

According to the aforementioned dual orthogonal six-dimensional force sensor, it is characterized in that one end of each elastic link is connected to the middle part of the corresponding elastic beam. the

According to the aforementioned method of using a dual orthogonal six-dimensional force sensor, it is characterized in that:

When measuring X and Mz components, the measurement circuit is composed of strain gauges attached to the root of the elastic beam on the YOZ plane;

When measuring the Z and My components, the measurement circuit is composed of strain gauges attached to the root of the elastic beam on the XOY plane;

When measuring the Y and Mx components, the measurement circuit is composed of the strain gauges attached to the root of the elastic beam on the XOZ plane.

The present invention has the following advantages:

1. Simple structure

The sensor is connected as a whole by the upper platform and the lower platform through elastic connecting rods, the structure is simple and compact, easy to patch, and the symmetry is good, which is convenient for processing and miniaturization, and reduces the cost.

2. Large strain deformation ratio

The elastic connecting rod is connected with the middle part of the elastic beam. Under the action of force or moment, the elastic beam becomes "S" deformation. At the same time, the elastic hinge of the elastic connecting rod makes full use of the characteristic that the tensile and compressive strength of the material is greater than the bending strength, so that the measurement direction The force in the direction is much larger than the force in the non-measurement direction, and the interference is reduced, so that the strain deformation ratio of the force in the measurement direction is larger.

3. Decoupling

The three sets of elastic connecting rods of the sensor are perpendicular to each other, which greatly reduces the interference of the measurement component on other components. In addition, the elastic connecting rods are equipped with biaxial elastic hinges, so that the elastic rods are similar to two-force rods, and the decoupling ability is better.

4. The number of strain gauges is small

The X, Mz components, Z and My components, Y and Mx components of the sensor use 4 strain gauges respectively, totaling 12 pieces.

Description of drawings

Fig. 1 is a structural schematic diagram of a dual orthogonal six-dimensional force sensor;

Fig. 2 is the Z direction view of Fig. 1;

Fig. 3 is a cross-sectional view along the direction A of Fig. 2;

Fig. 4 is a B-direction sectional view of Fig. 2;

Fig. 5 is a C-direction sectional view of Fig. 3;

Fig. 6 is a bridge diagram of six components of the sensor;

Label names in the figure: 1, normal working beam 1, 2, normal connecting rod 1, 3, normal working beam 2, 4, normal connecting rod 2, 5, transverse working beam 1, 6, transverse connecting rod 1 , 7, transverse working beam 2, 8, transverse connecting rod 2, 9, axial connecting rod 1, 10, axial working beam 1, 11, axial working beam 2, 12, axial connecting rod 2, 13, upper Platform, 14, lower platform, 15, 16, 17, 18 are strain gauges attached to the axial working beam, 19, 20, 21, 22 are strain gauges attached to the normal working beam, 23, 24, 25, 26 Strain gauges attached to transverse working beams.

In Figure 6, U is the supply bridge voltage, dVx is the output increment of X component, dVy is the output increment of Y component, dVz is the output increment of Z component, dVmx is the output increment of Mx component, dVmy is the output increment of My component, dVmz Output delta for the Mz component. the

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings. the

Figure 1 shows a three-dimensional schematic diagram of a dual orthogonal six-dimensional force sensor. Including upper platform 13, lower platform 14, axial connecting rods 9,12, normal connecting rods 2,4, and transverse connecting rods 6,8. Among them, the connecting rods 9 and 12 are respectively connected with the elastic beams 10 and 11 of the lower platform YOZ plane, the connecting rods 2 and 4 are respectively connected with the elastic beams 1 and 3 of the lower platform XOZ plane, and the connecting rods 6 and 8 are respectively connected with the lower platform XOY The planar elastic beams 5 and 7 are connected to form a T-shaped structure respectively. The other ends of the six elastic connecting rods are all connected to the upper platform (13). the

When the sensor is working, since the three groups of elastic connecting rods are orthogonal to each other, when measuring a certain component force, the force of this group of elastic connecting rods is much greater than that of the other elastic connecting rods, and the anti-interference ability is strong. the

Figure 2 is a front view of the sensor structure, Figures 3, 4, and 5 are cross-sectional views, and Figure 6 is a bridge diagram of six component strain gauges. 3 is a schematic diagram of the Y and Mx component patches. The strain gauges 15, 16, 18, and 17 form the Y component measurement circuit, and the strain gauges 15, 16, 17, and 18 form the Mx component measurement circuit. the

Fig. 4 is a schematic diagram of X and Mz component patches, the strain gauges 19, 20, 22, 21 form the X component measurement circuit, and the strain gauges 19, 20, 21, 22 form the Mz component measurement circuit. the

Fig. 5 is a schematic diagram of the Z and My component patches. The strain gauges 23, 24, 26, and 25 form the Z component measurement circuit, and the strain gauges 23, 24, 25, and 26 form the My component measurement circuit. the

The dual orthogonal six-dimensional force sensor makes full use of mechanical decomposition and electrical decomposition, and the decoupling effect is remarkable. In addition, it also has the advantages of simple structure and large strain-to-deformation ratio, and can be widely used in the fields of robots, mining, wind tunnel force measurement, automobile inspection, and elevator cable tension measurement. the

Claims (4)

1. A dual orthogonal six-dimensional force sensor, characterized in that it comprises: One upper platform (13), one lower platform (14), two transverse connecting rods (6, 8), two axial connecting rods (9, 12), two normal connecting rods (2, 4); The lower platform (14) is composed of XOY plane, YOZ plane and ZOX plane to form a semi-closed cavity structure, the upper platform (13) is a cube, and the upper platform (13) is located in the semi-closed cavity structure of the lower platform (14); In the XOY plane of the lower platform (14), there are four grooves parallel to each other along the Y direction, forming three transverse beams parallel to each other, and the two outer transverse beams are called transverse working beams (5, 7); the above The two transverse connecting rods (6, 8) are respectively connected between the middle parts of the two transverse working beams (5, 7) and the upper platform (13), and the transverse connecting rods (6, 8) are parallel to the Z axis; The YOZ plane of the lower platform (14) has four grooves parallel to each other along the Z direction, forming three axial beams parallel to each other, and the two axial beams on the outside are called axial working beams (10, 11 ); the above two axial connecting rods (9, 12) are respectively connected between the middle parts of the two axial working beams (10, 11) and the upper platform (13), and the axial connecting rods (9, 12) and X axis parallel; The ZOX plane of the lower platform (14) has four grooves parallel to each other along the X direction, forming three normal beams parallel to each other, and the two outer normal beams are called normal working beams (1, 3 ); the above two normal connecting rods (2, 4) are respectively connected between the middle parts of the two normal working beams (1, 3) and the upper platform (13), and the normal connecting rods (2, 4) and Y axis parallel. 2. The dual orthogonal six-dimensional force sensor according to claim 1, characterized in that: The upper platform (13) is provided with positioning holes for connecting models. 3. The dual orthogonal six-dimensional force sensor according to claim 1, characterized in that: Both ends of the transverse connecting rods (6, 8), axial connecting rods (9, 12) and normal connecting rods (2, 4) are provided with biaxial elastic hinges. 4. utilize the measuring method of dual orthogonal six-dimensional force sensor claimed in claim 1, it is characterized in that: When measuring X and Mz components, a total of four strain gauges (15, 16, 17, 18) pasted on the roots of two axial working beams (10, 11) form a measurement circuit; When measuring the Y and Mx components, four strain gauges (19, 20, 21, 22) pasted on the roots of the two ends of the normal working beam (1, 3) form a measurement circuit; When measuring the Z and My components, four strain gauges (23, 24, 25, 26) pasted on the roots of the two ends of the transverse working beam (5, 7) form a measurement circuit.