CN111975759B - An optical sensor-embedded artificial muscle and its use and preparation method - Google Patents
An optical sensor-embedded artificial muscle and its use and preparation method Download PDFInfo
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- CN111975759B CN111975759B CN202010738865.3A CN202010738865A CN111975759B CN 111975759 B CN111975759 B CN 111975759B CN 202010738865 A CN202010738865 A CN 202010738865A CN 111975759 B CN111975759 B CN 111975759B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
- B25J9/00—Programme-controlled manipulators
- B25J9/10—Programme-controlled manipulators characterised by positioning means for manipulator elements
- B25J9/1075—Programme-controlled manipulators characterised by positioning means for manipulator elements with muscles or tendons
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
- B25J19/00—Accessories fitted to manipulators, e.g. for monitoring, for viewing; Safety devices combined with or specially adapted for use in connection with manipulators
- B25J19/0095—Means or methods for testing manipulators
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L1/00—Measuring force or stress, in general
- G01L1/24—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet
- G01L1/241—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet by photoelastic stress analysis
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Abstract
本发明公开了一种光学传感器嵌入式的人工肌肉及其使用和制备方法。目前气动肌肉驱动系统的反馈控制主要依赖于外部压力传感器和位置传感器或编码器的使用实现。本发明包括光学压力检测端盖、人工肌肉基体和光学长度检测端盖。人工肌肉基体包括弹性筒身、光长度检测膜片和光压力检测膜片。光压力检测膜片、光长度检测膜片分别固定在弹性筒身内腔的压力检测端、长度检测端。光压力检测膜片的两侧不连通。光长度检测膜片的两侧通过通气孔连通。弹性筒身的内侧面吸光。光压力检测膜片及光长度检测膜片的外侧面反光。本发明通过设计光学传感器来反馈人工肌肉的收缩长度和收缩力，具有重量轻、顺应性好等方面的优势。
The invention discloses an optical sensor-embedded artificial muscle and its use and preparation method. The current feedback control of pneumatic muscle actuation systems mainly relies on the use of external pressure sensors and position sensors or encoders. The present invention includes an optical pressure detection end cap, an artificial muscle base and an optical length detection end cap. The artificial muscle base includes an elastic cylinder, an optical length detection diaphragm and an optical pressure detection diaphragm. The optical pressure detection diaphragm and the optical length detection diaphragm are respectively fixed on the pressure detection end and the length detection end of the inner cavity of the elastic cylinder body. The two sides of the optical pressure detection diaphragm are not connected. The two sides of the optical length detection film are communicated through the ventilation holes. The inner side of the elastic barrel absorbs light. The outer sides of the light pressure detection film and the light length detection film reflect light. By designing an optical sensor to feedback the contraction length and contraction force of the artificial muscle, the invention has the advantages of light weight, good compliance and the like.
Description
Technical Field
The invention belongs to the technical field of soft robots, and particularly relates to an optical sensor embedded soft pneumatic artificial muscle.
Background
The field of soft robots is at a position in favour of wearable devices and human-machine interaction due to their light weight and compliance. For such applications, position and force perception is crucial to enhance human-computer interaction, and implementing these functions in a software system is a challenge due to the non-linear nature of the software material. Feedback control of current pneumatic muscle-driven systems relies primarily on the use of external pressure sensors and position sensors or encoders. While this is suitable for some robotic systems, the additional sensing hardware adds complexity to the design and offsets the advantages of soft robots in terms of light weight, compliance, etc. Particularly in the case of wearable devices, external sensing may add bulk and weight to the wearer and inhibit movement thereof.
Disclosure of Invention
The invention aims to provide a soft pneumatic artificial muscle with an embedded optical sensor.
The invention relates to an optical sensor embedded artificial muscle, which comprises an optical pressure detection end cover, an artificial muscle matrix and an optical length detection end cover. The two ends of the artificial muscle matrix are respectively a pressure detection end and a length detection end. The optical pressure detection end cover and the optical length detection end cover are respectively arranged at the pressure detection end and the length detection end of the artificial muscle matrix. The artificial muscle base body comprises an elastic cylinder body, an optical length detection diaphragm and an optical pressure detection diaphragm. The optical pressure detection diaphragm and the optical length detection diaphragm are respectively fixed at the pressure detection end and the length detection end of the inner cavity of the elastic cylinder body. The two sides of the light pressure detection diaphragm are not communicated. The two sides of the optical length detection membrane are communicated through the vent holes. The inner side surface of the elastic tube body absorbs light. The outer side surfaces of the optical pressure detection diaphragm and the optical length detection diaphragm reflect light. And an optical pressure detection sensor is arranged on the inner side of the optical pressure detection end cover. And an optical length detection sensor is arranged on the inner side of the optical length detection end cover. Both the optical pressure detection sensor and the optical length detection sensor can emit light and can detect the intensity of received light.
Preferably, the artificial muscle matrix further comprises a spacing ring and a reinforcing fiber net. The reinforced fiber net is embedded in the side wall of the elastic cylinder body to divide the elastic cylinder body into an outer cylinder body and an inner cylinder body. A plurality of spacing rings that arrange in proper order all inlay inside the lateral wall of elasticity stack shell pressure measurement end, restrict the deformation of the pressure measurement end of elasticity stack shell. The light pressure detection diaphragm is positioned at the edge of the part of the elastic cylinder body limited by the limiting ring.
Preferably, the reinforcing fiber net and the limiting ring are formed by winding Kevlar fiber wires. The reinforcing fiber net is formed by interweaving two groups of spiral lines with opposite rotation directions.
Preferably, the light absorption material is a mixture of platinum-gold cured silica gel and black organic silicone pigment; the light reflecting material is a mixture of platinum-cured silica gel and a white organic silicone pigment.
Preferably, the optical pressure detection end cap and the optical length detection end cap both comprise base end cap components with the same structure. The base end cap assembly includes a tip connector, a cap body, and a shielding aluminum plate. The end connector main part is cylindricly, and inner edge is provided with a plurality of threading pieces. Each threading block is provided with a threading hole. The fiber lines at the two ends of the reinforced fiber net respectively pass through the threading holes on the two end connectors. The cover body is fixed in the end connector. The shielding aluminum plate is fixed on the inner side of the cover body. The optical pressure detection sensor and the optical length detection sensor have the same structure and both comprise a light emitting diode and a photodiode. The light emitting diode and the photodiode are respectively arranged on two sides of the corresponding shielding aluminum plate.
Preferably, the edges of the outward side surfaces of the optical length detection membranes are provided with light absorption rings;
preferably, two light guide members are further mounted on the inner side of the optical length detection end cover. The light emitting position and the light receiving position of the two light guide pieces and the optical length detection sensor. An air pipe is arranged on the optical pressure detection end cover or the optical length detection end cover; the two ends of the trachea are respectively connected with the inner cavity of the artificial muscle matrix and the air source.
The use method of the optical sensor embedded artificial muscle comprises the following steps:
step one, calibrating the optical pressure detection sensor and the optical length detection sensor.
And step two, using soft pneumatic artificial muscles to drive in the continuous detection.
2-1, filling the soft pneumatic artificial muscle into a mechanical system as a power source;
and 2-2, the light emitting diodes in the optical pressure sensor and the optical length sensor continuously emit light rays in a divergent manner, and the two groups of light rays are reflected by the optical pressure detection diaphragm and the optical length detection diaphragm respectively and enter the photodiodes in the optical pressure sensor and the optical length sensor.
2-3, the expansion of the soft pneumatic artificial muscle is driven by the inflation and deflation of the soft pneumatic artificial muscle. When the soft pneumatic artificial muscle is shortened, the distance from the optical length detection diaphragm to the optical length sensor is reduced, so that the light intensity detected by a photodiode in the optical length sensor is increased, and the current length of the soft pneumatic artificial muscle is deduced according to the light intensity value detected by the optical length sensor.
When the pressure in the soft pneumatic artificial muscle is increased, the range of the protrusion of the optical pressure detection diaphragm to the optical pressure sensor is increased, so that the light intensity detected by a photodiode in the optical pressure sensor is reduced, and the current internal pressure of the soft pneumatic artificial muscle is deduced according to the light intensity value detected by the optical pressure sensor.
Preferably, the step-specific process of the using method of the optical sensor embedded artificial muscle is as follows:
1-1, filling air with gradually changed air pressure into muscles through a combination of a proportional valve and an electromagnetic valve, and collecting the air pressure through an air pressure sensor; in the whole testing process, the length, the internal pressure, the optical pressure detection sensor and the light intensity detected by the photodiode in the optical length detection sensor of the soft pneumatic artificial muscle are continuously recorded.
1-2, obtaining a light-pressure relation curve between the light intensity detected by the optical pressure detection sensor and the internal pressure of the soft pneumatic artificial muscle and a light-length relation curve between the light intensity detected by the optical length detection sensor and the length of the soft pneumatic artificial muscle through discrete point fitting.
The preparation method of the optical sensor embedded artificial muscle comprises the following steps:
step one, forming a die cavity for pouring an inner cylinder body by matching a vertically arranged cylindrical inner die with a cylindrical first outer die; the inner side surface of the first outer die is provided with latticed bulges, and the end part of one end of the inner side surface is provided with a plurality of circles of bulges. Pouring a light absorption material between the inner mold and the first outer mold to form an inner cylinder body; the outer side surface of the inner cylinder body is provided with a grid-shaped groove, and one end of the inner cylinder body is provided with a plurality of circles of annular grooves. The latticed grooves are formed by interweaving a plurality of left-handed spiral lines and a plurality of right-handed spiral lines. Both ends tip of inner barrel body lateral surface all has the nodical of a plurality of levogyration helices and dextrorotation helix.
And step two, sleeving the two ends of the inner mold on the two end connectors and fixing the two end connectors through positioning pins, so that the plurality of threading holes in the end connectors abut against a plurality of spiral line intersection points at the end part of the inner cylinder body. A fiber line is wound along the grid-shaped grooves on the inner barrel body, so that the Kevlar fiber line passes through all positions of the grid-shaped grooves and passes through all the threading holes of the two end connectors. Then a plurality of spacing rings are wound by the fiber wires.
Removing the first outer die, and installing a second outer die with the inner diameter larger than that of the first outer die; pouring a light-absorbing material between the inner cylinder body and the second outer mold to form an outer cylinder body; the outer barrel completely covers the fiber thread. The inner cylinder body and the outer cylinder body jointly form an elastic cylinder body; and taking the inner mold out of the elastic cylinder body. At this time, the length detection end in the elastic cylinder body is arranged downwards.
Step four, casting the optical length detection diaphragm: placing a first membrane mould with an exhaust pin at the length detection end below the elastic cylinder body; an annular bulge is arranged at the edge of the end part of the first membrane mould; then pouring a reflective material at the first membrane mould through an injector to form an optical length detection membrane; after the optical length detection diaphragm is solidified, the elastic barrel body is turned over, so that the annular groove in the outer side face of the optical length detection diaphragm is arranged upwards, the first diaphragm die is disassembled, and light absorption materials are poured in the annular groove in the outer side face of the optical length detection diaphragm to form a light absorption ring.
Step five, casting the light pressure detection diaphragm: inserting a second diaphragm die with a flat end face into the pressure detection end below the elastic cylinder body; and then pouring a reflective material at the second membrane mould through an injector to form the light pressure detection membrane.
And step six, completely installing the optical pressure detection end covers and the optical length detection end covers at two ends of the elastic cylinder body.
The invention has the beneficial effects that:
1. the invention provides an optical sensor embedded soft pneumatic artificial muscle, which feeds back the contraction length and the contraction force of the artificial muscle by designing an optical sensor, has the advantages of light weight, good compliance and the like compared with the existing artificial muscle feeding back information through external sensing hardware, particularly greatly reduces the volume and the load of a wearer when being applied to wearable equipment, and is more portable.
2. The invention converts the internal pressure of the artificial muscle into the bending deformation degree of the optical pressure detection diaphragm, and judges the bending deformation degree of the optical pressure detection diaphragm through the light intensity reflected by the optical pressure detection diaphragm to the optical pressure detection sensor, thereby realizing the detection of the internal pressure of the artificial muscle.
3. The invention converts the length of the artificial muscle into the distance from the optical length detection diaphragm to the end part, and judges the distance from the optical length detection diaphragm to the end part through the light intensity reflected by the optical pressure detection diaphragm to the optical pressure detection sensor, thereby realizing the length detection of the artificial muscle.
4. The optical electronic element of the artificial muscle can easily enter and exit the muscle, can be detached and replaced, has high recycling performance and greatly reduces the cost. And the optical sensor does not have the common oxidation or leakage problem of the conductive liquid sensor, and has high safety.
5. The artificial muscle has wide application range, overcomes the nonlinear characteristic of soft materials, and can be applied to the fields of mechanical arms, soft robots, medical rehabilitation equipment and the like.
Drawings
FIG. 1 is a schematic view of the overall structure of the present invention;
FIG. 2 is a schematic side view of the invention after expansion;
FIG. 3 is an exploded view of the present invention;
FIG. 4a is a schematic diagram of the internal structure of the artificial muscle matrix according to the present invention;
FIG. 4b is a schematic structural diagram of an optical length detection film according to the present invention;
FIG. 5 is an exploded view of an optical length sensor end cap according to the present invention;
FIG. 6 is an exploded view of an optical pressure sensor end cap according to the present invention;
FIG. 7 is a schematic view of the present invention from an initial state to an expanded state;
FIG. 8 is a schematic flow chart of the preparation method of the present invention.
Detailed Description
The invention is further described below with reference to the accompanying drawings.
As shown in figures 1 and 2, the optical sensor embedded soft pneumatic artificial muscle comprises an optical pressure detection end cover 1, an artificial muscle matrix 2 and an optical length detection end cover 3. The artificial muscle matrix 2 is cylindrical, and expands along the radial direction and shortens the length after being inflated with air. The two ends of the artificial muscle matrix 2 are respectively a pressure detection end and a length detection end. The optical pressure detection end cover 1 and the optical length detection end cover 3 are respectively installed at a pressure detection end and a length detection end of the artificial muscle matrix 2 and are respectively used for detecting the pressure and the total length inside the artificial muscle matrix 2.
As shown in fig. 3 and 4a, the artificial muscle base body 2 includes an elastic cylinder body 4, a spacing collar 5, a reinforced fiber mesh 6, an optical length detection diaphragm 8 and an optical pressure detection diaphragm 7. The reinforced fiber net 6 is embedded in the side wall of the elastic cylinder body 4 to divide the elastic cylinder body 4 into an outer cylinder body 4-1 and an inner cylinder body 4-2. The outer barrel body 4-1 and the inner barrel body 4-2 are formed by two times of pouring and are tightly fixed together. The reinforcing fiber net 6 can increase the strength of the artificial muscle matrix 2 and avoid local large-scale deformation of the artificial muscle matrix 2. Four spacing rings 5 that arrange in proper order all inlay inside the lateral wall of the pressure detection end of elasticity stack shell 4, restrict the deformation of elasticity stack shell 4 for the shape before and after aerifing of the pressure detection end of elasticity stack shell 4 remains unchanged. The reinforcing fiber net 6 and the spacing ring 5 are formed by winding Kevlar fiber wires. The reinforcing fiber net 6 is formed by interweaving two groups of eight-thread spiral lines with opposite rotation directions and is formed by winding one fiber line.
As shown in fig. 4a and 4b, the optical pressure detecting diaphragm 7 and the optical length detecting diaphragm 8 are respectively fixed at the pressure detecting end and the length detecting end of the inner cavity of the elastic barrel body 4, and both have a distance from the end portions, so as to leave a space for the propagation and reflection of light. The optical pressure detection diaphragm 7 is positioned at the edge of the part of the elastic cylinder body 4 limited by the limiting ring 5 and cannot be expanded along with the expansion of the elastic cylinder body 4; the optical pressure detection diaphragm 7 divides the elastic cylinder 4 into two independent chambers, and the pressures in the two chambers can be different, so that the optical pressure detection diaphragm 7 can be deformed in a concave-convex manner along with the change of the internal pressure of the elastic cylinder 4.
the light absorption material is a mixture of platinum-On-Dragon skin and black organic silicone pigment (SilcPig), and can absorb light (infrared light) to a great extent, reduce optical reflectivity and prevent ambient infrared light from influencing optical signals of the optical sensor; the mixture of the reflective material platinum-gold cured silica gel and the white organic silicone pigment can improve the optical reflectivity of the diaphragm to the maximum extent. The mass fractions of the silicone pigment in the light absorbing material and the light reflecting material are both 3 percent
As shown in fig. 5 and 6, the optical pressure detection end cap 1 and the optical length detection end cap 3 each include a base end cap assembly having the same structure. The base end cap assembly includes an end connector 9, a cover 10 and a shielding aluminum plate 11. The end connector 9 main part is cylindric, and inner edge is provided with eight threading pieces. The eight threading blocks are provided with threading holes. The fiber lines at the two ends of the reinforced fiber net 6 respectively penetrate through the threading holes on the two end connectors 9, so that the fixation of the optical pressure detection end cover 1 and the optical length detection end cover 3 with the artificial muscle matrix 2 is realized. A cover 10 is secured within the end connector 9 for closing the end of the artificial muscle base 2. The shielding aluminum plate 11 is fixed to the inner side of the cover 10, and separates the inner side of the cover 10 into a light emitting area and a light receiving area which are not interfered with each other. The side wall of the end connector 9 is provided with a positioning hole 16 for positioning a mould during artificial muscle casting. The outer side of the cover 10 is provided with a closing plate 17.
The optical pressure detection end cap 1 and the optical length detection end cap 3 are respectively provided with an optical pressure detection sensor 14 and an optical length detection sensor 15. The optical pressure detecting sensor 14 and the optical length detecting sensor 15 have the same structure, and each includes a light emitting diode 14-1 and a photodiode 14-2. The light emitting diode 14-1 and the photodiode 14-2 are respectively installed on both sides of the corresponding shielding aluminum plate 11. The shielding aluminum plate can prevent light emitted at the side of the light emitting diode 14-1 from directly entering the photodiode 14-2. The light emitting diode 14-1 is used for emitting light; the photodiode 14-2 is used to receive and detect the intensity of light reflected by the light pressure detecting diaphragm 7 or the light length detecting diaphragm 8, and to judge the internal pressure and length of the artificial muscle based on the received light intensity.
Two light guides 18 are also mounted on the inside of the optical length detection end cap 3. The light guide 18 is an optical fiber. The two light guide members 18 are respectively aligned with the light emitting diode 14-1 and the photodiode 14-2 in the optical length detection sensor 15 to prolong the light source divergence point of the optical length detection sensor 15, so that the phenomenon that the light transmission is blocked due to uneven stretching of muscles near the end cover when the air cavity is expanded is avoided.
An air pipe 19 is arranged on the optical pressure detection end cover 1 or the optical length detection end cover 3; the two ends of the air pipe 19 are respectively connected with the inner cavity of the artificial muscle matrix 2 and the air source, so that the inflation and deflation of the artificial muscle matrix 2 are realized, and the driving of the artificial muscle is realized.
As shown in fig. 7, the detection principle of the present invention is as follows:
when the whole length of the artificial muscle matrix 2 is shortened due to gas filling or external load change, the parts of the artificial muscle matrix 2 except the position limited by the limiting ring 5 are shortened in equal proportion, and at the moment, the distance from the optical length detection diaphragm 8 to the optical length sensor is reduced; since the light emitted by the photodiode 14-2 is emitted in a divergent manner, the longer the distance the light travels, the larger the light coverage area, and the smaller the light intensity per unit area, so that when the distance from the optical length detection diaphragm 8 to the optical length sensor decreases, the travel distance of the light decreases, and the photodiode 14-2 detects that the light intensity increases (i.e., the relationship between the light intensity received by the optical length sensor and the length of the artificial muscle base 2 is a monotonically decreasing function); from this relationship the length of the artificial muscle base 2 can be calculated.
When the internal air pressure of the artificial muscle matrix 2 is increased due to the fact that air is filled or external load changes, the pressure difference between two sides of the optical pressure detection diaphragm 7 is increased, the amplitude of the optical pressure detection diaphragm 7 protruding to the optical pressure sensor is increased, namely the curvature of the outer convex surface of the optical pressure detection diaphragm 7 is increased; the light emitted by the optical pressure sensor tends to disperse more when reflected by the optical pressure detection diaphragm 7, so that the light intensity detected by the photodiode 14-2 decreases (namely, the light intensity received by the optical pressure sensor is in a relationship with the internal pressure of the artificial muscle matrix 2 which is a monotonically increasing function); from this relationship, the internal pressure of the artificial muscle base 2 can be calculated.
The use method of the optical sensor embedded soft pneumatic artificial muscle comprises the following steps:
step one, the optical pressure detection sensor 14 and the optical length detection sensor 15 are calibrated.
1-1, carrying out a plurality of no-load tests on the soft pneumatic artificial muscle to characterize the response of the optical length sensor and the pressure sensor and the muscle contraction range. The optical pressure detection end cover 1 is suspended, so that the artificial muscle base body 2 is vertically arranged, and the optical length detection sensor 15 is fixed at the free end of the muscle.
1-2, filling air with gradually changed air pressure into the muscle through a combination of a proportional valve and an electromagnetic valve (and pre-loading the muscle to 1 standard atmospheric pressure before pressurization so as to eliminate any relaxation in the test setting), wherein the air pressure is acquired through an air pressure sensor; the length, internal pressure, light intensity detected by the optical pressure detection sensor 14 and the photodiode 14-2 in the optical length detection sensor 15 of the soft pneumatic artificial muscle are continuously recorded in the whole testing process.
1-3, obtaining a light-pressure relation curve between the light intensity detected by the optical pressure detection sensor 14 and the internal pressure of the soft pneumatic artificial muscle and a light-length relation curve between the light intensity detected by the optical length detection sensor 15 and the length of the soft pneumatic artificial muscle through discrete point fitting. In the subsequent detection process, points are respectively taken on the light-pressure relation curve and the light-length relation curve of the light intensity detected by the optical pressure detection sensor 14 and the optical length detection sensor 15, so that the length and the internal pressure of the corresponding soft pneumatic artificial muscle can be obtained.
1-4, the soft pneumatic artificial muscle is subjected to an occlusion force test to characterize the relationship between the muscle contraction force and the length. In order to measure the force, the muscle is connected to a mechanical test system, the optical length detection end cover 3 is fixed on the base of the test bench, the optical pressure detection end cover 1 is connected with a mechanical push rod, and a pressure sensor is connected between the optical length detection end cover and the mechanical push rod to test and acquire the push rod force, namely the muscle contraction force; in each test, the mechanical push rod pushes muscles at a certain speed, the air pressure in the muscles is constant, and the relationship between the muscle contraction force and the length is recorded; and sequentially changing the air pressure, and repeating the experiment to successfully calibrate.
And step two, using soft pneumatic artificial muscles to drive in the continuous detection.
2-1, filling the soft pneumatic artificial muscle into a mechanical system as a power source;
2-2, the light emitting diode 14-1 in the optical pressure sensor and the optical length sensor continuously emits light in a divergent shape, and the two groups of light are respectively reflected by the optical pressure detection diaphragm 7 and the optical length detection diaphragm 8 and enter the photodiode 14-2 in the optical pressure sensor and the optical length sensor.
2-3, the expansion of the soft pneumatic artificial muscle is driven by the inflation and deflation of the air source to the soft pneumatic artificial muscle. When the soft pneumatic artificial muscle is shortened, the distance from the optical length detection diaphragm 8 to the optical length sensor is reduced, so that the light intensity detected by the photodiode 14-2 in the optical length sensor is increased, and the current length of the soft pneumatic artificial muscle is obtained according to the light intensity value detected by the optical length sensor and the light-pressure relation curve obtained in the step one.
When the pressure in the soft pneumatic artificial muscle is increased, the protruding amplitude of the optical pressure detection diaphragm 7 towards the optical pressure sensor is increased, so that the light intensity detected by the photodiode 14-2 in the optical pressure sensor is reduced, and the current internal pressure of the soft pneumatic artificial muscle is obtained according to the light intensity value detected by the optical pressure sensor and the light-length relation curve obtained in the step one.
As shown in fig. 8, the method for preparing the optical sensor embedded soft pneumatic artificial muscle comprises the following steps:
step one, forming a die cavity for pouring the inner barrel body 4-2 by matching a vertically arranged cylindrical inner die 20 and a cylindrical first outer die 21; the inner side surface of the first outer die 21 is provided with grid-shaped protrusions, and one end part of the inner side surface is provided with four circles of protrusions. Pouring a light-absorbing material between the inner mold 20 and the first outer mold 21 to form an inner barrel 4-2; the outer side surface of the inner cylinder body 4-2 is provided with a grid-shaped groove, and one end of the inner cylinder body is provided with four circles of annular grooves. The grid-shaped grooves are formed by interweaving eight left-handed spiral lines and eight right-handed spiral lines. The end parts of the two ends of the outer side surface of the inner barrel body 4-2 are respectively provided with eight intersection points of the left-handed spiral line and the right-handed spiral line.
And step two, sleeving the two end connectors 9 on the two ends of the inner mold 20 and fixing the two end connectors by positioning pins, so that the eight thread holes in the end connectors 9 are abutted against the eight spiral line intersection points at the end parts of the inner cylinder body 4-2. A kevlar thread is wound along the grid-like grooves on the inner barrel so that the kevlar thread passes through all positions of the grid-like grooves and passes through all the threading holes of the two end connectors 9. And then four spacing rings 5 are wound by Kevlar fiber wires.
Step three, removing the first outer die 21 and installing a second outer die 22 with the inner diameter larger than that of the first outer die 21; pouring a light-absorbing material between the inner cylinder 4-2 and the second outer mold 22 to form an outer cylinder 4-1; the outer barrel 4-1 completely covers the kevlar thread. The inner cylinder 4-2 and the outer cylinder 4-1 together form an elastic cylinder 4, and after the silica gel is solidified, the positioning pin is pulled out, and the inner mold 20 is taken out of the elastic cylinder 4. At this time, the length detection end in the elastic barrel 4 is set downward.
Step four, casting the optical length detection diaphragm 8: a first membrane mould 24 with an exhaust pin 23 is placed at the length detection end below the elastic barrel body 4; an annular bulge is arranged at the edge of the end part of the first membrane mould 24; then pouring a reflective material at the first membrane mould 24 through an injector to form the optical length detection membrane 8; after the optical length detection diaphragm 8 is cured, the elastic barrel body 4 is turned over, so that the annular groove on the outer side surface of the optical length detection diaphragm 8 is arranged upwards, the first diaphragm mold 24 is detached, and light absorption materials are poured into the annular groove on the outer side surface of the optical length detection diaphragm 8 to form the light absorption ring 12. Finally, the vent pin 23 is removed.
Step five, casting the light pressure detection diaphragm 7: a second diaphragm die 25 with a flat end face is inserted into the pressure detection end below the elastic barrel body 4; then pouring a reflective material at the second membrane mould 25 through an injector to form the light pressure detection membrane 7; after curing, the second membrane mold 25 is removed.
Step six, repairing holes left on the elastic cylinder body 4 during injection pouring; completely installing an optical pressure detection end cover 1 and an optical length detection end cover 3 at two ends of an elastic cylinder body 4; and the connection parts of the elastic cylinder body 4, the optical pressure detection end cover 1 and the optical length detection end cover 3 are sealed through light absorption materials.
Claims (10)
1. An optical sensor embedded artificial muscle comprises an artificial muscle base body (2); the method is characterized in that: the device also comprises an optical pressure detection end cover (1) and an optical length detection end cover (3); two ends of the artificial muscle matrix (2) are respectively a pressure detection end and a length detection end; the optical pressure detection end cover (1) and the optical length detection end cover (3) are respectively arranged at the pressure detection end and the length detection end of the artificial muscle matrix (2); the artificial muscle matrix (2) comprises an elastic cylinder body (4), an optical length detection diaphragm (8) and an optical pressure detection diaphragm (7); the optical pressure detection diaphragm (7) and the optical length detection diaphragm (8) are respectively fixed at the pressure detection end and the length detection end of the inner cavity of the elastic cylinder body (4); the two sides of the light pressure detection diaphragm (7) are not communicated; the two sides of the optical length detection membrane (8) are communicated through a vent hole (13); the inner side surface of the elastic cylinder body (4) absorbs light; the outer side surfaces of the light pressure detection diaphragm (7) and the light length detection diaphragm (8) are reflective; an optical pressure detection sensor (14) is arranged on the inner side of the optical pressure detection end cover (1); an optical length detection sensor (15) is arranged on the inner side of the optical length detection end cover (3); both the optical pressure detection sensor (14) and the optical length detection sensor (15) are capable of emitting light and detecting the intensity of received light.
2. An optical sensor embedded artificial muscle according to claim 1, wherein: the artificial muscle matrix (2) also comprises a spacing ring (5) and a reinforcing fiber net (6); the reinforced fiber net (6) is embedded in the side wall of the elastic cylinder body (4) to divide the elastic cylinder body (4) into an outer cylinder body (4-1) and an inner cylinder body (4-2); the plurality of limiting rings (5) which are sequentially arranged are all embedded in the side wall of the pressure detection end of the elastic cylinder body (4) to limit the deformation of the pressure detection end of the elastic cylinder body (4); the light pressure detection diaphragm (7) is positioned at the edge of the part of the elastic cylinder body (4) limited by the limiting ring (5).
3. An optical sensor embedded artificial muscle according to claim 2, wherein: the reinforcing fiber net (6) and the limiting ring (5) are formed by winding Kevlar fiber wires; the reinforcing fiber net (6) is formed by interweaving two groups of spiral lines with opposite rotation directions.
4. An optical sensor embedded artificial muscle according to claim 1, wherein: the elastic cylinder body (4) is made of light absorption materials; the light pressure detection diaphragm (7) and the light length detection diaphragm (8) both adopt reflecting materials; the light absorption material is a mixture of platinum-cured silica gel and black organic silicone pigment; the reflecting material is a mixture of platinum-gold cured silica gel and white organic silicone pigment.
5. An optical sensor embedded artificial muscle according to claim 1, wherein: the optical pressure detection end cover (1) and the optical length detection end cover (3) both comprise basic end cover components with the same structure; the basic end cover assembly comprises a terminal connector (9), a cover body (10) and a shielding aluminum plate (11); the main body of the end connector (9) is cylindrical, and a plurality of threading blocks are arranged at the edge of the inner end of the end connector; each threading block is provided with a threading hole; fiber wires at two ends of the reinforced fiber net (6) respectively pass through the threading holes on the two end connectors (9); the cover body (10) is fixed in the end connector (9); the shielding aluminum plate (11) is fixed on the inner side of the cover body (10); the optical pressure detection sensor (14) and the optical length detection sensor (15) have the same structure and respectively comprise a light-emitting diode (14-1) and a photodiode (14-2); the light emitting diode (14-1) and the photodiode (14-2) are respectively arranged on two sides of the corresponding shielding aluminum plate (11).
6. An optical sensor embedded artificial muscle according to claim 1, wherein: and the edges of the outward side surfaces of the optical length detection membranes (8) are provided with light absorption rings (12).
7. An optical sensor embedded artificial muscle according to claim 1, wherein: two light guide pieces (18) are further mounted on the inner side of the optical length detection end cover (3); the two light guide pieces (18) are respectively aligned with the light emitting position and the light receiving position of the optical length detection sensor (15); an air pipe (19) is arranged on the optical pressure detection end cover (1) or the optical length detection end cover (3); two ends of the air pipe (19) are respectively connected with the inner cavity of the artificial muscle matrix (2) and an air source.
8. The method of using an optical sensor embedded artificial muscle according to claim 1, wherein:
calibrating an optical pressure detection sensor (14) and an optical length detection sensor (15);
step two, driving by using artificial muscles in continuous detection;
2-1, putting the artificial muscle into a mechanical system as a power source;
2-2, light emitting diodes (14-1) in the optical pressure detection sensor and the optical length detection sensor continuously emit light rays in a divergent shape, and the two groups of light rays are respectively reflected by the optical pressure detection diaphragm (7) and the optical length detection diaphragm (8) and enter the photodiodes (14-2) in the optical pressure detection sensor and the optical length detection sensor;
2-3, driving the artificial muscle to stretch and contract by inflating and deflating the artificial muscle; when the artificial muscle is shortened, the distance from the optical length detection diaphragm (8) to the optical length detection sensor is reduced, so that the light intensity detected by a photodiode (14-2) in the optical length detection sensor is increased, and the current length of the artificial muscle is deduced according to the light intensity value detected by the optical length detection sensor;
when the pressure in the artificial muscle is increased, the protruding amplitude of the optical pressure detection diaphragm (7) towards the optical pressure detection sensor is increased, so that the light intensity detected by a photodiode (14-2) in the optical pressure detection sensor is reduced, and the current internal pressure of the artificial muscle is deduced according to the light intensity value detected by the optical pressure detection sensor.
9. The use method of an optical sensor embedded artificial muscle according to claim 8, wherein: the specific process of the step one is as follows:
1-1, filling air with gradually changed air pressure into the artificial muscle through a combination of a proportional valve and an electromagnetic valve, and acquiring the air pressure through an air pressure sensor; continuously recording the length, the internal pressure, the light intensity detected by a photodiode (14-2) in an optical pressure detection sensor (14) and the light intensity detected by the photodiode (14-2) in an optical length detection sensor (15) of the artificial muscle in the whole test process;
1-2, obtaining a light-pressure relation curve between the light intensity detected by the optical pressure detection sensor (14) and the internal pressure of the artificial muscle and a light-length relation curve between the light intensity detected by the optical length detection sensor (15) and the length of the artificial muscle through discrete point fitting.
10. The method for preparing an optical sensor embedded artificial muscle as claimed in claim 1, wherein:
step one, forming a die cavity for pouring an inner cylinder body (4-2) by matching a vertically arranged cylindrical inner die (20) with a cylindrical first outer die (21); the inner side surface of the first outer die (21) is provided with grid-shaped bulges, and the end part of one end of the inner side surface is provided with a plurality of circles of bulges; pouring a light-absorbing material between the inner mold (20) and the first outer mold (21) to form an inner barrel body (4-2); the outer side surface of the inner cylinder body (4-2) is provided with a latticed groove, and one end of the inner cylinder body is provided with a plurality of circles of annular grooves; the latticed grooves are formed by interweaving a plurality of left-handed spiral lines and a plurality of right-handed spiral lines; the end parts of the two ends of the outer side surface of the inner barrel body (4-2) are respectively provided with a plurality of intersection points of the left-handed spiral line and the right-handed spiral line;
sleeving two end connectors (9) on two ends of the inner mold (20) and fixing the two end connectors through positioning pins, so that a plurality of threading holes in the end connectors (9) are abutted against a plurality of spiral line intersection points at the end part of the inner cylinder body (4-2); winding a fiber line along the latticed grooves on the inner barrel body, so that the Kevlar fiber line passes through all the positions of the latticed grooves and passes through all the threading holes of the two end connectors (9); then winding a plurality of limiting rings (5) by using fiber wires;
step three, removing the first outer die (21), and installing a second outer die (22) with the inner diameter larger than that of the first outer die (21); pouring a light-absorbing material between the inner cylinder (4-2) and the second outer die (22) to form an outer cylinder (4-1); the outer cylinder body (4-1) completely covers the fiber line; the inner cylinder body (4-2) and the outer cylinder body (4-1) together form an elastic cylinder body (4); taking the inner mold (20) out of the elastic cylinder body (4); at the moment, the length detection end in the elastic cylinder body (4) is arranged downwards;
step four, casting an optical length detection diaphragm (8): a first membrane mould (24) with an exhaust pin (23) is placed at the length detection end below the elastic cylinder body (4); an annular bulge is arranged at the edge of the end part of the first membrane mould (24); then pouring a reflective material at the first membrane mould (24) through an injector to form the optical length detection membrane (8); after the optical length detection diaphragm (8) is solidified, the elastic barrel body (4) is turned over, so that an annular groove on the outer side surface of the optical length detection diaphragm (8) is arranged upwards, the first diaphragm mold (24) is disassembled, and light absorption materials are poured in the annular groove on the outer side surface of the optical length detection diaphragm (8) to form a light absorption ring (12);
step five, casting a light pressure detection diaphragm (7): a second diaphragm die (25) with a flat end face is inserted into the pressure detection end below the elastic cylinder body (4); then pouring a reflective material at the second membrane mould (25) through an injector to form the light pressure detection membrane (7);
and sixthly, completely installing the optical pressure detection end cover (1) and the optical length detection end cover (3) at two ends of the elastic cylinder body (4).
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