CN103148983B - Three-dimensional force loading and calibration device of flexible touch sensor - Google Patents

Abstract

The invention belongs to the sensor testing technology, in particular to a three-dimensional force loading and calibration device for a flexible tactile sensor. The device includes an operating platform for placing samples and a clamping mechanism, a force loading device and a control mechanism, a direction and angle adjustment mechanism and a support frame. The force loading device and control mechanism is a pneumatic mechanism composed of a force loading rod, a tension and pressure sensor, a miniature cylinder, an air pressure regulating valve, an air source, and an electric control box; or a force loading rod, a tension and pressure sensor, a voice coil motor, a current Electromagnetic force mechanism composed of controller, electric control box, etc. The support frame is a simple support or a XYZ linear motion three-dimensional support frame composed of mechanical motion pairs. The force loading device is installed on the support frame above the operating table directly or through the direction and angle adjustment mechanism. The invention takes the loading force as the control quantity, the loading force can be adjusted smoothly and continuously, meets the static and dynamic calibration requirements of the sensor, and can realize force loading and calibration operations in any direction and angle in the upper hemisphere area of the working platform.

Description

Three-dimensional force loading and calibration device for flexible tactile sensor

technical field

The invention belongs to the sensor testing technology, in particular to a three-dimensional force loading and calibration device for a flexible tactile sensor.

Background technique

Flexible tactile sensors are a class of high-precision, high-resolution, high-response sensors that have similar perception capabilities to human skin and can measure large-area tactile information. Therefore, this type of sensor has become a hotspot in robotic skin research in recent years.

At present, the typical tactile sensor products include the pressure distribution test system launched by Tekscan Company of the United States. It uses a flexible array sensor. The sensor array is composed of two polyester films. Row conductors, when two films are stacked, the row conductors and column conductors cross each other to form a lattice composed of several row and column intersections. A pressure-sensitive semiconductor material is placed in the middle of each intersection point in the array to form a pressure-sensing point. When an external force acts on these sensing points, the resistance of the semiconductor changes proportionally with the change of the external force, and then it can detect a large area of force. This technology has been widely used in pressure distribution testing and analysis in many fields. In addition, the US SPI company, the Belgian RSscan company, etc. are also producing and using flexible pressure array sensors. In China, Xi'an Jiaotong University has studied a tactile sensor based on conductive rubber, which can not only obtain the shape characteristics of the object surface, but also obtain the object's slip information and relative velocity. The Department of Engineering Mechanics of Tsinghua University used conductive rubber as the sensor material and successfully developed a contact force sensing type human foot pressure distribution measurement system with 251 dots. The Shanghai Institute of Microsystem and Information Technology of the Chinese Academy of Sciences developed a method for the fabrication of capacitive flexible tactile sensors using polydimethylsiloxane (PDMS) as the intermediate layer and flexible polyimide (PI) as the substrate. The Hefei Institute of Intelligent Machinery of the Chinese Academy of Sciences has used conductive rubber to develop an "artificial skin" that can detect three-dimensional forces. This is a flexible multi-dimensional tactile sensor system that is similar to human skin tissue, has an overall multi-layer array structure, and can perceive multi-dimensional force information. . The sensor uses multiple layered cross-arranged row/column wires for scanning, and realizes three-dimensional force measurement with high-precision algorithms by detecting the resistance value change between the cross nodes after the sensor is stressed. This kind of flexible tactile sensor is made of flexible sensitive materials, which can be bent into various non-planar shapes, suitable for the measurement of non-planar tactile information, and can be used in aspects such as robotic fingers, joints, and artificial skin, showing a wide range of applications prospect. In addition to piezoresistive and capacitive technologies, robotic three-dimensional force tactile sensor arrays developed based on new materials and technologies such as polyvinylidene fluoride (PVDF) and optical waveguides at home and abroad have also developed vigorously.

However, due to differences in material composition, production process, processing technology, and use environment, no matter what materials and technologies are used to make sensors, there will be errors between the actual input and output measurement values. For occasions that require precise measurement, these errors will seriously affect the accuracy of the detection results, and even lead to wrong conclusions, so only the calibrated sensor can be put into practical application. On the other hand, the existing sensor calibration technology mostly uses the linear least squares method, but due to the influence of detection principles, material properties, multi-dimensional nonlinear coupling and other factors, this calibration method is not suitable for nonlinear occasions. Therefore, in order to improve the calibration accuracy, the development of nonlinear calibration methods has become the development direction in recent years. Nonlinear calibration involves many algorithms for solving nonlinear equations, such as iterative methods, bionic algorithms, etc., which require a large amount of data as the basis for solving, but the current calibration methods are mostly manual operations, which cannot meet the needs of solving nonlinear equations. intensive sampling requirements. In addition, the existing calibration device is hardly able to accurately calibrate the sensor in different force directions and angles, and lacks support for dynamic measurement, so it is difficult to comprehensively and effectively evaluate the mechanical characteristics of the sensor. In view of this, there is an urgent need for a calibration platform and method that can provide flexible tactile sensors with continuous force in different directions and angles, and continuously collect time-dependent data, so as to meet the requirements of static and dynamic calibration of sensors.

After retrieval, the current patent documents related to multi-dimensional force sensor calibration devices include DE19616312, CN101109670A, CN101281073A and CN102175388A. Among them, CN101281073A and CN102175388A are the closest to the present application. CN101281073A discloses a calibration device and method for a planar array mechanical sensor. This patent uses a stepping motor to control the position of the force probe, which can apply pressure in the vertical direction, but cannot achieve multi-directional and multi-angle force. However, CN102175388A discloses a device capable of calibrating curved surface flexible tactile sensors. This patent uses a grating ruler to improve positioning accuracy, and realizes attitude control and force loading of the force loading head through a parallel mechanism, but the device cannot precisely control the force applied. direction and angle. That is to say, the force-adding devices provided in these two patent documents still cannot meet the requirements of static and dynamic calibration of the sensor, and due to the limitation of the working principle, the displacement must be changed to generate the loading force instead of directly outputting the loading force. This is very inconvenient for actual operation.

Contents of the invention

The object of the present invention is to provide a device for three-dimensional force loading and calibration of flexible tactile sensors to meet the requirements of static and dynamic calibration of the sensor, aiming at the problems existing in the prior art.

Technical scheme of the present invention is as follows:

The three-dimensional force loading and calibration device of the flexible tactile sensor of the present invention includes an operation platform for placing samples, a clamping mechanism for fixing samples, a force loading and control mechanism and a support frame, and it is characterized in that the force loading and control The mechanism is a pneumatic mechanism composed of a force loading rod, a tension and pressure sensor, a miniature cylinder, an air pressure regulating valve and an air source, an electric control box, an air circuit and a circuit connection, or a force loading rod, a tension and pressure sensor, a voice coil An electromagnetic force mechanism composed of a motor, a current controller, an electric control box and corresponding circuit connection parts; the force loading device in the force loading and control mechanism is installed above the operating table through a support frame.

The support frame is a simply supported beam frame, and a vertically movable guide rail is arranged on the support beam frame, and the force loading device is installed at the bottom of the vertical guide rail; or it is paid by mechanical movement, such as a nut screw mechanism, a gear The rack mechanism or worm gear mechanism constitutes a three-dimensional support frame with linear motion capability in the X-Y-Z direction. The operating table is installed at the bottom of the support frame that can move along the X-axis and Y-axis directions, and the force loading device is installed on it. It can move vertically The bottom end of the Z-axis guide rail, so that the force loading device can move linearly in the X-Y-Z three-dimensional direction relative to the operating table.

The force loading device is installed on the bottom end of the vertical guide rail of the simply supported beam frame or the bottom end of the Z-axis guide rail of the three-dimensional support frame. Rolling bearings are arranged at the connection between the bottom end of the bottom end and the force loading device, so that the force loading device rotates relative to the guide rail, so as to meet the needs of different usage situations. For the convenience of operation, angle scale marks can also be set on the guide rail to indicate the rotation angle.

In actual use, in order to meet the change of the direction of the loading force, the force loading device can also be set on an angle adjustment mechanism first, and then the angle adjustment mechanism is directly connected to the bottom end of the guide rail, or connected to the bottom end of the guide rail through rolling bearings . The angle adjustment mechanism includes a semicircular slide rail on a vertical plane and a matching slide block, the force loading device is fixedly connected with the slide block, and the slide block slides on the semicircle slide rail, with a force loading device The included angle with the vertical guide rail or the axis of the Z-axis guide rail is within the range of plus or minus 90°, and the angle scale can also be marked on the side of the semicircular slide rail to facilitate the operation.

The force loading and control mechanism in the present invention uses two schemes of pneumatic force or electromagnetic force. In the pneumatic boosting scheme, a miniature cylinder is used as the force loading device, air or nitrogen is used as the working medium, and the cylinder pressure is controlled by an electric proportional valve to realize continuous stepless adjustment of the loading force. The loading force can be calculated from the cylinder pressure and calculated. Compared with the detection value of the tension and pressure sensor, the closed-loop precise control of the loading force is realized. The micro cylinder is used as the force loading device, and the force loading rod is instantly increased through the instantaneous pressurization of the cylinder, which can be applied to the dynamic calibration of the sensor. In the electromagnetic boosting scheme, the voice coil motor is used as the force loading device, and the precise control of the thrust of the voice coil motor is realized by adjusting the current flowing through the motor, and by comparing with the detection value of the tension and pressure sensor, the closed-loop precise control of the loading force is achieved the goal of. The voice coil motor is used as the force loading device, and the loading force can be increased tens or even hundreds of times in a very short time by increasing the current instantaneously, which can be used for dynamic calibration of sensors. The difference between the force loading device and the previous force loading device is that the micro cylinder and the voice coil motor are directly controlled by the loading force, instead of the moving distance of the drive motor in the past. Therefore, it is avoided in principle. The sudden jump of the loading force generated during the boosting process realizes the smooth and continuous adjustment of the loading force and meets the requirements of static and dynamic calibration of the sensor.

The three-dimensional force loading and calibration device of the flexible tactile sensor of the present invention uses a three-dimensional support frame with a linear motion device in the X-Y-Z direction, and adjusts the force direction on the horizontal plane by setting a rolling bearing, and also uses a semicircle with an angle scale The guide rail controls the force angle on the vertical plane, so that in the upper hemisphere area of the working platform, force loading and calibration operations can be performed in any direction and angle, and the operation is very convenient, which will greatly expand its application range. the

Description of drawings

Further description will be made below through examples and accompanying drawings.

Fig. 1 is a structural schematic diagram of an embodiment of the pneumatic booster and control mechanism.

Fig. 2 is a structural schematic diagram of an embodiment of the electromagnetic force and control mechanism.

Fig. 3 is a schematic structural diagram of an embodiment of the device with the ability to adjust the horizontal direction and tilt angle.

Fig. 4 is a schematic structural view of an embodiment of the three-dimensional support frame with a linear motion device in the X-Y-Z direction.

Fig. 5 is a schematic diagram of the circuit module of the embodiment of the electric control box.

Detailed ways

Referring to Fig. 1, the force loading rod 1 made of hard plastic, aluminum alloy or stainless steel rod is connected with the tension and pressure sensor 2 through the threaded interface, and the tension and pressure sensor is connected with the piston 11 of the miniature cylinder through the threaded interface, and the miniature cylinder 10 is also connected to the angle adjustment slider 6 through a threaded interface, wherein the axes of the force loading rod 1, the tension and pressure sensor 2 and the miniature cylinder 10 coincide. The miniature cylinder 10 communicates with the air source 5 through the air pressure regulating valve 4 and the PU pipeline 3 . The electric control box 8 is respectively connected with the tension and pressure sensor 2 and the air pressure regulating valve 4 through the signal line 9 . The micro cylinder 10 uses air or nitrogen as the working medium, and through the control of the air pressure regulating valve 4, it realizes the stepless regulation of gas pressure and flow rate. The size of the air pressure is to realize the adjustment of the force applied by the force loading rod 1 to the calibrated sample. The air source 5 used is a high-pressure air cylinder or an air compressor, which is connected to the air pressure regulating valve 4 with a PU tube to provide the working medium for the miniature cylinder 10 . There is a hollow "concave" groove structure in the middle part of the angle adjustment slide block 6, so as to be connected with the "convex" glyph slide rail, and the slide block fixing screw 7 on the side of the slide block is used to lock the position of the slide block. The input end of the electric control box 8 is electrically connected with the output end of the tension-pressure sensor 2, and is used to receive the force detection signal of the tension-pressure sensor 2; the output end of the electric control box 8 is electrically connected with the input end of the pressure regulating valve 4, and the The signal is transmitted to the air pressure regulating valve 4; the electric control box 8 is equipped with a USB module, which is used to connect with the computer, and obtain the value of the loading force through computer conversion, and then control the entire force loading process.

Referring to Fig. 2, the force loading rod 1 made of hard plastic, aluminum alloy or stainless steel rod is connected to the tension and pressure sensor 2 through the threaded interface, and the tension and pressure sensor is connected to the mover 15 of the voice coil motor through the threaded interface, and The voice coil motor 14 is also connected to the angle adjustment slider 6 through a threaded interface, wherein the axes of the force loading rod 1 , the pull-pressure sensor 2 and the voice coil motor 14 coincide. The voice coil motor 14 and the current controller 13 are connected by wires 12 . The electric control box 8 is respectively connected with the tension and pressure sensor 2 and the current controller 13 through the signal wire 9 . The voice coil motor 14 relies on the electromagnetic force generated by the current to work, and the current can be continuously and accurately adjusted by the current controller 13 to realize stepless and continuous adjustment of the thrust of the motor. Since the force loading rod 1 and the mover 15 of the voice coil motor are integrally connected, changing the current in the voice coil motor 14 realizes the adjustment of the force applied by the force loading rod 1 to the calibrated sample. There is a hollow "concave" groove structure in the middle part of the angle adjustment slide block 6, so as to be connected with the "convex" glyph slide rail, and the slide block fixing screw 7 on the side of the slide block is used to lock the position of the slide block. The input end of electric control box 8 is electrically connected with the output end of pull-pressure sensor 2, is used to receive the force detection signal of pull-pressure sensor 2; The output end of electric control box 8 is electrically connected with the input end of current controller 13, will control The signal is transmitted to the current controller 13; the electric control box 8 is equipped with a USB module for connecting with a computer, and the value of the loading force is obtained through computer conversion, and then controls the entire force loading process.

Referring to FIG. 3 , the top of the semicircular slide rail 16 is fixedly connected to the bottom of the direction adjusting disc 18 , and the rotating bearing 17 is nested in the middle of the direction adjusting disc 18 , and is connected to the end of the Z-axis guide rail through the rotating bearing. The angle adjustment slide block 6 is dynamically matched with the semicircular slide rail 16, the bottom of the slide block has a threaded joint 19 connected with the force loading device, and the side of the slide block is dynamically fitted with the fixed screw 7 of the slide block. The semicircular slide rail 16 is semicircular curved with the force point as the center, the cross section is "convex" shape, and the surface is marked with an angle scale, which can accurately indicate the inclination angle. The direction adjusting disc 18 is connected to the Z-axis guide rail through the rotating bearing 17, so it can rotate on the Z-axis guide rail as the axis, and cooperate with the angle scale on the surface to precisely control the rotation direction angle in the horizontal plane. There is a hollow "concave" groove structure in the middle of the angle adjustment slider 6, which is movably connected with the semicircular "convex" slide rail 16, and can make arc movements along the semicircular slide rail to achieve precise adjustment of inclination in the vertical plane Angle, the slider fixing screw 7 on the side of the slider is used to lock the position of the slider. Because the force loading device is fixedly connected with the angle adjustment slider 6 as a whole, and the semicircular slide rail 16 is fixedly connected with the direction adjustment disc 18 as a whole, so the combined adjustment of the direction adjustment disc 18 and the angle adjustment slider 6 realizes the operation Arbitrary adjustment of the force loading direction and angle centered on the force loading point in the upper hemisphere area of the stage.

Referring to Fig. 4, the Y-axis support frame 23 is vertically and fixedly installed on the Y-axis guide rail 22, the Y-axis dovetail guide groove 21 is installed on the side of the console 33 parallel to the Y-axis, and the Y-axis displacement adjustment knob 20 is placed on the other side of the console 33. side, its mounting surface is perpendicular to the mounting surface of the Y-axis dovetail guide groove 21. The Y-axis guide rail 22 is movably connected with the Y-axis dovetail guide groove 21 , and is movably connected with the Y-axis displacement adjustment knob 20 through a screw pair. Since the Y-axis support frame 23 is integrally connected with the Y-axis guide rail 22 , turning the Y-axis displacement adjustment knob 20 can drive the Y-axis support frame 23 to move linearly along the Y-axis dovetail guide groove 21 .

The X-axis guide rail 25 is perpendicular to the Y-axis, fixed horizontally on the top of the Y-axis support frame 23, the X-axis dovetail guide groove 26 is installed parallel to the bottom of the X-axis beam 27, and the X-axis displacement adjustment knob 24 is placed on the top side of the Y-axis support frame 23 . Since the X-axis beam 27 is movably connected with the X-axis guide rail 25 through the X-axis dovetail guide groove 26, and is movably connected with the X-axis displacement adjustment knob 24 through the rack-and-pinion structure, so turning the X-axis displacement adjustment knob 24 realizes Drive the X-axis beam 27 to move linearly along the X-axis guide rail 25 .

The side of the Z-axis support frame 30 is fixedly connected to the end of the X-axis beam 27 and is perpendicular to the horizontal plane. The inside of the Z-axis support frame 30 is a hollow structure, and the Z-axis guide groove 28 is fixedly installed, and the Z-axis displacement adjustment knob 31 is placed outside the Z-axis support frame 30 . The Z-axis guide rail 29 is movably connected with the Z-axis guide groove 28 through the Z-axis support frame 30, and is movably connected with the Z-axis displacement adjustment knob 31 through the rack-gear structure, so turning the Z-axis displacement adjustment knob 31 realizes Drive the Z-axis guide rail 29 to move linearly along the Z-axis guide groove 28 .

The end of the Z-axis guide rail 29 is connected to the direction adjustment disc 18 through a rotating bearing, and the direction adjustment disc 18 is fixedly connected with the semicircular slide rail 16 as a whole, so turning the Y-axis displacement adjustment knob 20, the X-axis displacement adjustment knob 24 and the Z-axis displacement Adjusting the knob 31 realizes the three-dimensional linear motion of the driving direction and angle adjusting device in the X-Y-Z direction.

The operating table 33 is located directly below the Z-axis guide rail 29, and is dynamically connected with the entire three-dimensional support frame structure through the Y-axis dovetail guide groove 21 on the side. The sample holder 32 is placed on the surface of the operating table 33 to fix the sample.

Referring to Fig. 5, the signal input module 34 of the electric control box is electrically connected to the signal output end of the tension and pressure sensor, the signal output module 35 is electrically connected to the signal input end of the pressure regulating valve or the current controller, and the electric control box is connected through the USB communication module 37 It is electrically connected with the computer 38 . The signal input module 34 receives the thrust signal transmitted by the tension and pressure sensor in real time, and provides it to the single-chip microcomputer 36 for processing after the analog-to-digital conversion and the signal amplification module 39; The computer 38 exchanges information, and submits the execution command to the force control mechanism through the signal output module 35 .

In the above embodiments, the materials such as the miniature cylinder, tension and pressure sensors, and voice coil motors are all directly purchased from the market.

Claims (6)

1. the three-dimensional force of a flexible touch sensation sensor loads and caliberating device, comprise that one for placing the operator's console of sample and the clamping device of fixed sample, force loading device and control gear and bracing frame, described force loading device and control gear are the aerodynamic force mechanisms being grouped into by power load bar, tension-compression sensor, minitype cylinder, air pressure regulator and source of the gas, photoelectric control box, gas circuit and circuit connecting section, or the electromagnetic force mechanism being grouped into by power load bar, tension-compression sensor, voice coil motor and current controller, photoelectric control box and corresponding circuit connecting section; Described force loading device is arranged on the top of operator's console by bracing frame, it is characterized in that, support frame as described above is a freely-supported roof beam structure, is provided with a vertically moving guide rail on this freely-supported roof beam structure, and force loading device is arranged on this vertical guide rail bottom; Or by mechanical motion, paid the three-dimensional bracing frame with X-Y-Z direction linear motion device forming, operator's console is arranged on can realize the bracing frame bottom of moving along Y-axis or X-direction, force loading device is arranged on the bottom of the Z axis guide rail that can move as vertical direction, makes charger at X-Y-Z three-dimensional, make traveling priority with respect to operator's console.

2. the three-dimensional force of flexible touch sensation sensor as claimed in claim 1 loads and caliberating device, it is characterized in that, described force loading device is arranged on the bottom of vertical guide rail bottom or three-dimensional bracing frame Z axis guide rail, be, in the bottom of guide rail and the junction of force loading device, rolling bearing is set, force loading device is rotated with respect to vertical guide rail or Z axis guide rail.

3. the three-dimensional force of flexible touch sensation sensor as claimed in claim 2 loads and caliberating device, it is characterized in that, when the bottom of described vertical guide rail bottom or Z axis guide rail and the junction of force loading device arrange rolling bearing, on vertical guide rail or Z axis guide rail, angle index mark is set.

4. the three-dimensional force of flexible touch sensation sensor as claimed in claim 1 loads and caliberating device, it is characterized in that, described force loading device is arranged on the bottom of vertical guide rail bottom or Z axis guide rail, first force loading device to be arranged on an angle adjusting mechanism, then this angle adjusting mechanism is connected with vertical guide rail or Z axis guide rail bottom, or is connected with vertical guide rail or Z axis guide rail bottom by rolling bearing.

5. the three-dimensional force of flexible touch sensation sensor as claimed in claim 4 loads and caliberating device, it is characterized in that, described angle adjusting mechanism comprises the semicircle slide rail and the slide block with matching that are positioned on vertical plane, force loading device is fixedly connected with slide block, slide block slides on semicircle slide rail, and drive charger changes in the angle with vertical guide rail or Z axis rail axis is the scope of positive and negative 90 °.

6. the three-dimensional force of flexible touch sensation sensor as claimed in claim 5 loads and caliberating device, it is characterized in that, the semicircle slide rail subscript of described angle adjusting mechanism is marked with angle index.