Stepped elastic beam for six-axis force sensor

Abstract

Disclosed in the present invention is a stepped elastic beam for a six-axis force sensor. The stepped elastic beam comprises a central platform, a stepped main beam, a floating beam, rims, and strain gauges, wherein the central platform is connected to the floating beam on the outer side by means of the stepped main beam, and the rims at four corners are connected to the floating beam; 24 strain gauges are pasted to the stepped main beam to form six sets of Wheatstone bridges; and when the force / torque of a certain dimension acts on the center of the stepped elastic beam, the sensor deforms, and the resistance value of the strain gauge at a corresponding position is changed, such that an output voltage of a corresponding bridge is changed, and the numerical value of the force / torque of the dimension can be obtained by measuring the change of the voltage. A structure is simple, the sensitivity is high, and the inter-dimensional coupling is low.

Description

A stepped elastic beam for a six-dimensional force sensor Technical Field

[0001] The present invention belongs to the technical field of sensors, and in particular relates to a stepped elastic beam of a six-dimensional force sensor. Background Art

[0002] Six-dimensional force sensors can simultaneously sense three-dimensional force components and three-dimensional torque components in space, acquiring complete force information in complex systems. They have broad application prospects in intelligent robotics, aerospace, biomedical research, medical devices, and automotive fields. Currently, the most widely used multi-dimensional force sensor is a resistive strain gauge based on a cross-beam structure. These sensors use strain gauges to convert the deformation of the sensor into voltage changes, enabling the measurement of both force and torque components.

[0003] Since most of the strain-type multi-dimensional force sensors currently developed have problems such as complex structure, large inter-dimensional coupling interference, and low sensitivity, it is of great significance to design an elastic beam structure with a simple structure, high sensitivity and low inter-dimensional coupling.

[0004] Summary of the Invention

[0005] To solve the above problems, the present invention discloses a stepped elastic beam for a six-dimensional force sensor, which makes up for the deficiencies of the prior art and has the advantages of simple structure, high sensitivity and low inter-dimensional coupling.

[0006] To achieve the above object, the technical solution of the present invention is as follows:

[0007] A stepped elastic beam of a six-dimensional force sensor comprises a center platform, a stepped main beam, a floating beam, a wheel rim and a strain gauge;

[0008] The center platform is a rectangular column with a square cross section. There are four force application holes on the center platform, through which forces and torques act on the center platform. The four sides of the center platform are connected to the stepped main beam.

[0009] The stepped main beam is composed of four stepped rectangular cross beams arranged in a cross shape; the stepped rectangular cross beam is composed of a first-level main beam, a second-level main beam and a third-level main beam in sequence; the first-level main beam has a square cross section, one end of which is connected to the center platform and the other end is connected to the second-level main beam; the second-level main beam has a square cross section, one end of which is connected to the first-level main beam and the other end is connected to the third-level main beam; the third-level main beam has a square cross section, one end of which is connected to the second-level main beam and the other end is connected to the floating beam;

[0010] The floating beams are four rectangular thin-walled beams with rectangular cross-sections; the center of the inner side of the floating beam is connected to the stepped main beam, and the two ends are connected to the wheel rim;

[0011] The wheel rim is composed of four sector-shaped annular columns with a sector-shaped cross section. Both ends of the sector-shaped annular columns are connected to the floating beam. A fixing hole is provided on each sector-shaped annular column for fixing the elastic beam to the shell.

[0012] The measurement principle of the six-dimensional force sensor is to stick 24 strain gauges on the stepped main beam to form 6 groups of Wheatstone bridges, 3 groups on the first-level main beam and 3 groups on the second-level main beam. Among them, there are 4 symmetrical strain gauges on the side wall of the first-level main beam of the Y-direction stepped main beam, forming a bridge circuit for measuring the X-direction force Fx; there are 4 symmetrical strain gauges on the side wall of the first-level main beam of the X-direction stepped main beam, forming a bridge circuit for measuring the Y-direction force Fy; there are 4 symmetrical strain gauges on the upper and lower surfaces of the first-level main beam of the X-direction stepped main beam, forming a bridge circuit for measuring the Z-direction force Fz; there are 4 symmetrical strain gauges on the upper and lower surfaces of the second-level main beam of the Y-direction stepped main beam, forming a bridge circuit for measuring the X-direction moment Mx; there are 4 symmetrical strain gauges on the upper and lower surfaces of the second-level main beam of the X-direction stepped main beam, forming a bridge circuit for measuring the Y-direction moment My; there are 4 symmetrical strain gauges on the outer side wall of the second-level main beam of the X-direction stepped main beam, forming a bridge circuit for measuring the Z-direction moment Mz. When a force / torque of a certain dimension acts on the center of the stepped elastic beam, the sensor deforms, and the resistance of the strain gauge at the corresponding position changes, causing the output voltage of the corresponding bridge to change. By measuring the change in voltage, the value of the force / torque of that dimension can be obtained.

[0013] The beneficial effects of the present invention are:

[0014] (1) The main beam of the stepped elastic beam structure of the six-dimensional force sensor designed by the present invention adopts a three-level stepped structure, which effectively improves the sensitivity of the sensor while ensuring the strength of the sensor.

[0015] (2) The stepped elastic beam structure of the six-dimensional force sensor designed in the present invention is based on the resistance strain principle and adopts a stepped main beam and a thin-walled floating beam structure, which reduces the inter-dimensional coupling error and improves the sensor accuracy.

[0016] (3) The stepped elastic beam structure of the six-dimensional force sensor designed by the present invention is simple and easy to process. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] FIG1 is a structural schematic diagram 1 of a stepped elastic beam of the present invention.

[0018] FIG2 is a second structural diagram of the stepped elastic beam of the present invention.

[0019] FIG3 is a schematic diagram of the position of the strain gauge patch of the present invention.

[0020] FIG4 is a schematic diagram of six bridge circuits in the present invention. DETAILED DESCRIPTION

[0021] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0022] As shown in FIG1 , in order to conveniently describe the direction, a spatial Cartesian coordinate system is established as shown in FIG1 .

[0023] The present invention proposes a stepped elastic beam of a six-dimensional force sensor, comprising a center platform 1, a stepped main beam 2, a floating beam 3, a wheel rim 4 and a strain gauge 7;

[0024] The center platform 1 is a rectangular column with a square cross section. There are four force application holes 6 on the center platform 1, through which forces and moments act on the center platform 1. The four sides of the center platform 1 are connected to the stepped main beam 2.

[0025] The stepped main beam 2 is composed of four stepped rectangular beams arranged in a cross shape; the stepped rectangular beam is composed of a first-level main beam 21, a second-level main beam 22 and a third-level main beam 23 in sequence; the first-level main beam 21 has a square cross section, one end of which is connected to the center platform 1 and the other end is connected to the second-level main beam 22; the second-level main beam 22 has a square cross section, one end of which is connected to the first-level main beam 21 and the other end is connected to the third-level main beam 23; the third-level main beam 23 has a square cross section, one end of which is connected to the second-level main beam 22 and the other end is connected to the floating beam 3;

[0026] The floating beams 3 are four rectangular thin-walled beams with rectangular cross-sections. The center of the inner side of the floating beam 3 is connected to the stepped main beam 2, and both ends are connected to the wheel rim 4.

[0027] The wheel rim 4 is composed of four sector-shaped cylinders, each having a sector-shaped cross section. Both ends of the sector-shaped cylinders are connected to the floating beam 3. Each sector-shaped cylinder is provided with a fixing hole 5 for fixing the elastic beam to the housing.

[0028] Figure 3 shows the placement of the 24 strain gauges described in the present invention, along with their corresponding numbers, R1 to R24. All strain gauges are identical except for their numbers, meaning they have the same initial resistance. Their resistance decreases with contraction and increases with extension. The strain gauges are attached to each main beam at the location where the strain is greatest when the beam is subjected to stress. Strain gauges R1 and R7 are pasted on the upper and lower surfaces of the first main beam of the stepped rectangular crossbeam in the negative direction of X. Strain gauges R2 and R8 are pasted on the upper and lower surfaces of the second main beam of the stepped rectangular crossbeam in the positive direction of Y. Strain gauges R3 and R9 are pasted on the upper and lower surfaces of the first main beam of the stepped rectangular crossbeam in the positive direction of X. Strain gauges R4 and R10 are pasted on the upper and lower surfaces of the second main beam of the stepped rectangular crossbeam in the negative direction of Y. Strain gauges R5 and R11 are pasted on the upper and lower surfaces of the second main beam of the stepped rectangular crossbeam in the positive direction of X. Strain gauges R6 and R12 are pasted on the upper and lower surfaces of the second main beam of the stepped rectangular crossbeam in the negative direction of X. Strain gauges R13 and R16 are pasted on The strain gauges R14 and R15 are pasted on the left and right side walls of the first main beam of the stepped rectangular crossbeam in the negative Y direction, the strain gauges R17 and R19 are pasted on the left and right side walls of the first main beam of the stepped rectangular crossbeam in the positive Y direction, the strain gauges R18 and R20 are pasted on the left and right side walls of the second main beam of the stepped rectangular crossbeam in the negative X direction, the strain gauges R21 and R23 are pasted on the left and right side walls of the first main beam of the stepped rectangular crossbeam in the positive X direction, and the strain gauges R22 and R24 are pasted on the left and right side walls of the second main beam of the stepped rectangular crossbeam in the positive X direction. All strain gauges are pasted on the position where the strain is the largest when each beam is subjected to force.

[0029] The measurement principle of the six-dimensional force sensor is that the input force / torque of a certain dimension acts on the center of the elastic body through the force hole, causing the sensor to deform, and the resistance of the strain gauge at the corresponding position changes, thereby changing the output voltage of the corresponding bridge. At the same time, due to the design of the structure, the output voltage of the remaining dimensions will not change significantly, which effectively reduces the inter-dimensional coupling interference, thereby improving the measurement accuracy of the sensor. Therefore, during use, it is only necessary to measure the voltage change of all 6 channels to obtain the value of the force / torque of each dimension. Let R0 represent the zero-position resistance value of the strain gauge, ΔR Fx , ΔR Fy , ΔR Fz , ΔR Mx , ΔR My , ΔR Mz They represent the resistance change of the strain gauge under the action of Fx, Fy, Fz, Mx, My, and Mz respectively. The change in the output voltage of each channel is as follows:

[0030] It should be noted that the above content merely illustrates the technical idea of ​​the present invention and cannot be used to limit the scope of protection of the present invention. For ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications all fall within the scope of protection of the claims of the present invention.

Claims

1. The stepped elastic beam of a six - dimensional force sensor, characterized in that: it includes a central platform, a stepped main beam, a floating beam, a rim and strain gauges; the central platform is a columnar body with a cuboid structure, and its cross - section is square; there are 4 force - applying holes on the central platform, and force and torque act on the central platform through the force - applying holes; the four side surfaces of the central platform are connected to the stepped main beam; the stepped main beam is composed of 4 stepped rectangular cross - beams in a cross shape; the stepped rectangular cross - beam is composed of a first - stage main beam, a second - stage main beam and a third - stage main beam in sequence; the cross - section of the first - stage main beam is square, one end of which is connected to the central platform and the other end is connected to the second - stage main beam; the cross - section of the second - stage main beam is square, one end of which is connected to the first - stage main beam and the other end is connected to the third - stage main beam; the cross - section of the third - stage main beam is square, one end of which is connected to the second - stage main beam and the other end is connected to the floating beam; the floating beam is composed of 4 rectangular thin - wall beams, and its cross - section is rectangular; the center of the inner side surface of the floating beam is connected to the stepped main beam, and both ends are connected to the rim; the rim is composed of 4 fan - shaped ring - shaped columns, and its cross - section is fan - shaped; both ends of the fan - shaped ring - shaped column are connected to the floating beam; there are fixed holes on each fan - shaped ring - shaped column for fixing the elastic beam to the housing.

2. The stepped elastic beam of the six - dimensional force sensor according to claim 1, characterized in that: the measurement principle is as follows: 24 strain gauges are pasted on the stepped main beam to form 6 groups of Wheatstone bridges, 3 groups on the first - stage main beam and 3 groups on the second - stage main beam; among them, there are 4 strain gauges symmetrically on the side walls of the first - stage main beam of the stepped main beam in the Y direction, which form a bridge circuit for measuring the X - direction acting force Fx; there are 4 strain gauges symmetrically on the side walls of the first - stage main beam of the stepped main beam in the X direction, which form a bridge circuit for measuring the Y - direction acting force Fy; there are 4 strain gauges symmetrically on the upper and lower surfaces of the first - stage main beam of the stepped main beam in the X direction, which form a bridge circuit for measuring the Z - direction acting force Fz; there are 4 strain gauges symmetrically on the upper and lower surfaces of the second - stage main beam of the stepped main beam in the Y direction, which form a bridge circuit for measuring the X - direction acting torque Mx; there are 4 strain gauges symmetrically on the upper and lower surfaces of the second - stage main beam of the stepped main beam in the X direction, which form a bridge circuit for measuring the Y - direction acting torque My; there are 4 strain gauges symmetrically on the outer side walls of the second - stage main beam of the stepped main beam in the X direction, which form a bridge circuit for measuring the Z - direction acting torque Mz. When a force / torque in a certain dimension acts on the center of the stepped elastic beam, the sensor deforms, the resistance values of the strain gauges at the corresponding positions change, so that the output voltage of the corresponding bridge changes, and the value of the force / torque in this dimension can be obtained by measuring the change in voltage.

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