Miniature fingertip multi-dimensional force sensor based on Hall effect

Abstract

The invention discloses a micro fingertip multi-dimensional force sensor based on a Hall effect, and particularly relates to the technical field of industrial automation, and the micro fingertip multi-dimensional force sensor comprises a magnetic body, a deformable flexible fingertip, a Hall sensor group and a base. The magnetic body and the Hall sensor group are embedded into the flexible fingertip and are fixed on the base; wherein the Hall sensor group comprises a Hall sensor 3a, a Hall sensor 3b and a Hall sensor 3c; when the flexible fingertips are stressed to generate elastic deformation, the magnetic bodies embedded in the flexible fingertips can generate displacement relative to the Hall sensor group to realize cooperative deformation; when a magnetic induction line penetrates through the Hall sensor group, the Hall sensor 3a, the Hall sensor 3b and the Hall sensor 3c respectively output proportional voltage signals according to the magnetic field intensity, and then sensing of external multi-dimensional force is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of industrial automation, and in particular to a miniature fingertip multi-dimensional force sensor based on the Hall effect. Background Art

[0002] Miniature fingertip multi-dimensional force sensors are widely used in robotics, virtual reality, medical devices, industrial automation, etc. Their main function is to accurately measure and feedback subtle force changes to meet the complex operation and control requirements in these fields.

[0003] A patent application filed by Zhejiang University of Technology with the patent number CN201911303848.0 for a flexible fingertip contact sensor and its preparation method still has some deficiencies in practical applications. Specifically:

[0004] 1. Too large: Existing force sensors are generally large in size and difficult to embed into the fingertip structure of a robotic gripper, thus limiting their use in more sophisticated and diverse applications.

[0005] 2. Excessive manufacturing costs due to complex structures: The sensitive components of these sensors are complex and require high manufacturing processes, which directly leads to increased production costs. This factor limits the widespread application and promotion of miniature fingertip multi-dimensional force sensors in the market. Summary of the invention

[0006] To this end, the present invention provides a miniature fingertip multi-dimensional force sensor with miniaturized size, simple structure, low manufacturing cost, and integrated Hall effect, so as to promote the wide engineering application of miniature fingertip multi-dimensional force sensor and solve the problems raised in the background technology.

[0007] In order to achieve the above-mentioned object, the present invention provides the following technical solutions: a miniature fingertip multi-dimensional force sensor based on the Hall effect, the miniature fingertip multi-dimensional force sensor comprising a magnetic body, a deformable flexible fingertip, a Hall sensor group and a base, the magnetic body and the Hall sensor group are both embedded in the flexible fingertip and fixed on the base; wherein the Hall sensor group comprises a Hall sensor 3a, a Hall sensor 3b and a Hall sensor 3c;

[0008] When the flexible fingertip is subjected to force and elastically deforms, the magnetic body embedded therein will be displaced relative to the Hall sensor group to achieve cooperative deformation; the N pole and S pole of the magnetic body are both located on the z-axis, and its magnetic flux lines start from the N pole, pass through the Hall sensor group, and finally return to the S pole; the Hall sensor 3a, the Hall sensor 3b and the Hall sensor 3c are evenly distributed in a ring along the z-axis and are located within the range of the magnetic flux lines of the magnetic body before and after the flexible fingertip is deformed;

[0009] When magnetic flux lines penetrate the Hall sensor group, the Hall sensor 3a, the Hall sensor 3b and the Hall sensor 3c respectively output proportional voltage signals according to the magnetic field strength, thereby realizing the perception of external multi-dimensional forces.

[0010] Preferably, the material of the deformable flexible fingertip includes but is not limited to silicone or TPU material.

[0011] Preferably, after the external force causing the elastic deformation disappears, the magnetic body returns to the initial state along with the flexible fingertip.

[0012] Preferably, the perception of external multi-dimensional force is obtained by fusing the stiffness matrix and voltage response of the flexible fingertip.

[0013] The present invention has the following advantages:

[0014] The present invention proposes a miniature fingertip multi-dimensional force sensor based on the Hall effect, including a new multi-dimensional force sensing mechanism based on the Hall effect, realizing the integrated design of the sensing element and the fingertip structure. This integrated design greatly simplifies the process of combining the miniature fingertip force sensor with the fingertip structure, eliminates the complicated strain gauge pasting process steps, and realizes the effective miniaturization of the sensor structure and significant cost reduction. The sensor of the present invention is easier to produce and deploy, which helps to expand its promotion and popularization in practical applications. Compared with the existing miniature fingertip force sensors, the present invention has significant advantages, including miniaturization in size, simplification in structure, reduction in manufacturing cost, and improvement in integration. These characteristics make the present invention more competitive in the market and conducive to its wide promotion and application in multiple application fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a non-forced state view of a miniature fingertip multi-dimensional force sensor based on the Hall effect disclosed by the present invention.

[0016] Figure 2 This is a view of the bending deformation state of the micro fingertip multi-dimensional force sensor under force.

[0017] Figure 3 This is the magnetic field distribution of the micro fingertip multi-dimensional force sensor when there is no force.

[0018] Figure 4 This is the magnetic field distribution of the micro fingertip multi-dimensional force sensor under force.

[0019] Figure 5 Experimental scheme for calibration of micro fingertip multi-dimensional force sensor.

[0020] Figure 6 This is the force response curve of the micro fingertip multi-dimensional force sensor.

[0021] In the figure: 1. Magnetic body; 2. Flexible fingertip; 3. Hall sensor group; 4. Base. DETAILED DESCRIPTION

[0022] The following is a description of the implementation of the present invention by specific embodiments. People familiar with the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] Example: Figure 1 As shown, this embodiment discloses a miniature fingertip multi-dimensional force sensor based on the Hall effect, and its main components include: a magnetic body 1, a flexible fingertip 2, a Hall sensor group 3 and a base 4. The Hall sensor group 3 includes a plurality of Hall sensors for detecting multi-dimensional force. In this embodiment, the Hall sensor group 3 specifically includes a Hall sensor 3a, a Hall sensor 3b and a Hall sensor 3c. The magnetic body 1 and the Hall sensor group 3 are both embedded in the flexible fingertip 2 and fixed on the base 4 to ensure the stability and functionality of the sensor.

[0024] like Figure 2 As shown, the flexible fingertip 2 adopts a flexible deformable material, such as silicone and TPU. These materials can produce elastic deformation under the action of external force. When the flexible fingertip 2 is subjected to elastic deformation, the magnetic body 1 embedded therein will be displaced relative to the Hall sensor group 3. When the external force disappears, the magnetic body 1 can return to its initial state with the flexible fingertip 2. This embodiment uses flexible materials to cover internal components and achieve coordinated deformation. Compared with the traditional solution, the mechanical connection structure is eliminated, the overall structure is significantly simplified, the production cost is reduced, and the reliability of the system is improved.

[0025] like Figure 3 As shown, the N pole 1a and S pole 1b of the magnetic body 1 are both located on the z-axis, and its magnetic flux lines 1c start from the N pole, pass through the Hall sensor group 3, and finally return to the S pole. The members of the Hall sensor group 3, Hall sensors 3a, Hall sensors 3b and Hall sensors 3c, are evenly distributed in a ring along the z-axis, and are located within the range of the magnetic flux lines 1c of the magnetic body 1 before and after the flexible fingertip 2 is deformed. When magnetic flux lines penetrate their structure, the Hall sensors 3a, Hall sensors 3b and Hall sensors 3c can output proportional voltage signals u1, u2, and u3 respectively according to the magnetic field strength.

[0026] like Figure 4As shown, during the elastic deformation of the flexible fingertip 2 under force, the magnetic body 1 is displaced relative to the Hall sensor group 3; the direction of the magnetic flux lines 1c generated by the magnetic body 1 will change accordingly, resulting in corresponding changes in the magnetic field strength acting on the Hall sensor 3a, Hall sensor 3b and Hall sensor 3c, and the voltage signals u1, u2, and u3 output by the Hall sensor 3a, Hall sensor 3b and Hall sensor 3c will also change accordingly, thereby realizing the perception of external force. The flexible fingertip 2 can be deformed in any direction in three-dimensional space. If the deformation direction is different, the change characteristics of the voltage signals u1, u2, and u3 output by the Hall sensor 3a, Hall sensor 3b and Hall sensor 3c are different, thereby realizing the perception of external multi-dimensional force. This is the uniqueness of the micro-fingertip multi-dimensional force sensor designed in this embodiment in terms of perception.

[0027] For the existing embodiment, the three-dimensional force [F x F y F z ] T It can be obtained by integrating the stiffness matrix C of the flexible fingertip 2 structure:

[0028]

[0029] For a more general embodiment, if the Hall sensor group 3 includes n Hall sensors, the three-dimensional force [F x F y F z ] T It can be combined in the following ways:

[0030]

[0031] The structural stiffness matrix C of the flexible fingertip 2 can be obtained through finite element method or experimental identification.

[0032] Figure 5 This is the experimental scheme for calibrating the micro fingertip multi-dimensional force sensor. The calibration experimental system mainly includes the micro fingertip multi-dimensional force sensor, dynamometer, ADC module, microcontroller, and signal processing system. The experimental identification steps of the stiffness matrix C are as follows:

[0033] Step 1: Use a dynamometer to apply a specific load F to the micro fingertip multi-dimensional force sensor along the x, y, and z axes, and construct a load matrix:

[0034]

[0035] Step 2: Collect the responses of Hall sensor 3a, Hall sensor 3b and Hall sensor 3c through the microcontroller and ADC module and record the responses of Hall sensor 3a, Hall sensor 3b and Hall sensor 3c in the x, y and z axis directions during the individual loading process, and construct a response matrix:

[0036]

[0037] Step 3: The stiffness matrix C can be obtained by Calculated.

[0038] In this embodiment, a load of 3N is applied to each direction of the micro fingertip multi-dimensional force sensor, namely:

[0039]

[0040] The measured response matrix is:

[0041]

[0042] Then the stiffness matrix C is:

[0043]

[0044] Then the three-dimensional force can be calculated according to [F x F y F z ]=C[u1 u2 u3] T Fusion obtained. Figure 6 F x 、F y 、F z Uniaxial loading response curve. Among them, The response curve of the force gauge is used to compare and verify the force F measured by the micro fingertip multi-dimensional force sensor. x 、F y 、F z Accuracy. Experimental results show that the three-dimensional force F x 、F y 、F z It can effectively decouple, and the maximum three-dimensional force measurement error is about 0.18 N. At present, the force measurement error level of micro fingertip force sensors at home and abroad is about 0.3 N. Therefore, the sensor of the present invention is ideal in force measurement performance.

[0045] Although the present invention has been described in detail above by general description and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements can be made to the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all belong to the scope of protection claimed by the present invention.

Claims

1. A miniature fingertip multi-dimensional force sensor based on Hall effect, characterized in that: The micro fingertip multi-dimensional force sensor comprises a magnetic body, a deformable flexible fingertip, a Hall sensor group and a base, wherein the magnetic body and the Hall sensor group are embedded in the flexible fingertip and fixed on the base; wherein the Hall sensor group comprises a Hall sensor 3a, a Hall sensor 3b and a Hall sensor 3c; When the flexible fingertip is subjected to force and elastically deforms, the magnetic body embedded therein will be displaced relative to the Hall sensor group to achieve cooperative deformation; the N pole and S pole of the magnetic body are both located on the z-axis, and its magnetic flux lines start from the N pole, pass through the Hall sensor group, and finally return to the S pole; the Hall sensor 3a, the Hall sensor 3b and the Hall sensor 3c are evenly distributed in a ring along the z-axis and are located within the range of the magnetic flux lines of the magnetic body before and after the flexible fingertip is deformed; When magnetic flux lines penetrate the Hall sensor group, the Hall sensor 3a, the Hall sensor 3b and the Hall sensor 3c respectively output proportional voltage signals according to the magnetic field strength, thereby realizing the perception of external multi-dimensional forces.

2. The miniature fingertip multi-dimensional force sensor based on the Hall effect according to claim 1, characterized in that: The material of the deformable flexible fingertip includes but is not limited to silicone or TPU material.

3. The miniature fingertip multi-dimensional force sensor based on Hall effect according to claim 1, characterized in that: After the external force causing the elastic deformation disappears, the magnetic body returns to its initial state along with the flexible fingertip.

4. The miniature fingertip multi-dimensional force sensor based on Hall effect according to claim 1, characterized in that: The perception of external multi-dimensional force is obtained by fusing the stiffness matrix and voltage response of the flexible fingertip.

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