CN114700975A

CN114700975A - Attitude sensor based on flexible optical waveguide and robot

Info

Publication number: CN114700975A
Application number: CN202210374864.4A
Authority: CN
Inventors: 赵慧婵; 周婧祎; 刘辛军
Original assignee: Tsinghua University
Current assignee: Tsinghua University
Priority date: 2022-04-11
Filing date: 2022-04-11
Publication date: 2022-07-05
Anticipated expiration: 2042-04-11
Also published as: CN114700975B

Abstract

The invention relates to an attitude sensor based on a flexible optical waveguide and a robot. The attitude sensor comprises an optical waveguide, a frame and a weight; the optical waveguide is arranged on the frame, the weight can be arranged on the frame in a sliding mode along a preset direction, the weight is connected with the surface of the cladding of the optical waveguide and corresponds to the inner core of the optical waveguide, and the preset direction is perpendicular to the axis of the inner core and parallel to the surface of the cladding. The weight of the attitude sensor can only be arranged on the frame in a sliding manner along a preset direction, so that the optical waveguide can realize the sensing of the absolute attitude through the gravity component of the weight, and compared with a gyroscope for realizing the attitude sensing by depending on angular velocity integration, the sensing is the absolute attitude, and the problem of the integration process and the accumulated error caused by the integration process is solved; the sliding direction of the weight is perpendicular to the axis of the inner core and parallel to the surface of the cladding, so that the output of the optical waveguide has a good linear relation with the sine value of the attitude angle, the optical waveguide has convenience in use, and the detection sensitivity is also ensured.

Description

Attitude sensor based on flexible optical waveguide and robot

Technical Field

The invention relates to the technical field of robots, in particular to an attitude sensor based on a flexible optical waveguide and a robot.

Background

The perception of the self-posture is an important prerequisite for human moving in the environment, and especially the perception of the absolute posture by taking gravity as a reference direction. The acquisition of the pose of itself in space is of equal importance for robots (e.g. mobile robots, robotic arms). At present, the attitude perception of the robot often adopts a gyroscope technology, and the attitude is obtained by integrating the angular velocity. In such a posture sensing manner, errors in the angular velocity measurement are accumulated, and finally, deviation of the posture can be caused.

Disclosure of Invention

In view of the above, it is necessary to provide an attitude sensor based on a flexible optical waveguide and a robot, in order to solve the problem that the robot employs a gyroscope technology and the attitude sensing is deviated.

A flexible optical waveguide-based attitude sensor, the attitude sensor comprising: optical waveguides, racks and weights;

the optical waveguide is arranged on the rack, the weight is arranged on the rack in a sliding mode along a preset direction, the weight is further connected with the surface of the cladding of the optical waveguide and corresponds to the inner core of the optical waveguide, and the preset direction is perpendicular to the axis of the inner core and parallel to the surface of the cladding.

In the attitude sensor, the weight is arranged on the rack in a sliding manner only along the preset direction, so that the optical waveguide can realize the sensing of the absolute attitude through the gravity component of the weight, and compared with a gyroscope for realizing the attitude sensing by depending on angular velocity integration, the absolute attitude is sensed, and the problem of the integration process and the accumulated error caused by the integration process is solved; the sliding direction of the weight is perpendicular to the axis of the inner core and parallel to the surface of the cladding, so that the output of the optical waveguide has a good linear relation with the sine value of the attitude angle, the optical waveguide has convenience in use, and the detection sensitivity is also ensured; the flexible material is used as a sensitive unit (namely an optical waveguide), and the flexible material has larger deformation even under the action of a tiny force, namely has an amplification effect on the force, so that the attitude sensor has higher sensitivity; the optical waveguide has robustness, the optical waveguide serving as a sensitive unit can resist overload load and has a certain damping and buffering effect, and the robustness can enhance the usability of the attitude sensor in use.

In one embodiment, the number of the inner cores of the optical waveguide is 1, and the shape of the inner core of the optical waveguide is linear.

In one embodiment, a slide rail is arranged on the rack, a slide block capable of sliding along the preset direction is arranged on the slide rail, and the slide block is connected with the heavy object.

In one embodiment, the attitude sensor further includes a first mounting member connected between the slider and the weight.

In one embodiment, the attitude sensor further includes a force transmission member connected between the weight and the cladding of the optical waveguide, the force transmission member corresponding to the inner core of the optical waveguide, and an area of a side surface of the force transmission member adjacent to the optical waveguide is smaller than an area of a side surface of the weight adjacent to the optical waveguide.

In one embodiment, the attitude sensor further comprises a second mounting member connected between the force-transmitting member and the weight.

In one embodiment, the rack comprises: the mounting device comprises a base, a mounting seat and a stand column for supporting the mounting seat above the base;

the optical waveguide is arranged on the base, and the heavy object is slidably arranged on the mounting seat.

In one embodiment, the mounting block can slide up and down along the upright.

In one embodiment, the upright is a screw, and the frame further comprises a nut in threaded connection with the upright, wherein the nut is used for locking the mounting seat at any height.

A robot comprising a flexible optical waveguide based attitude sensor as claimed in any preceding claim.

In the robot, the weight of the attitude sensor can only be arranged on the rack in a sliding manner along the preset direction, so that the optical waveguide can realize the sensing of the absolute attitude through the gravity component of the weight, and compared with a gyroscope for realizing the attitude sensing by depending on angular velocity integration, the sensing is the absolute attitude, and the problem of the integration process and the accumulated error caused by the integration process is solved; the sliding direction of the weight is perpendicular to the axis of the inner core and parallel to the surface of the cladding, so that the output of the optical waveguide has a good linear relation with the sine value of the attitude angle, the optical waveguide has convenience in use, and the detection sensitivity is also ensured; the flexible material is used as a sensitive unit (namely, an optical waveguide), and the flexible material has larger deformation even under the action of a tiny force, namely has an amplification effect on the force, so that the attitude sensor has high sensitivity; the optical waveguide has robustness, the optical waveguide serving as a sensitive unit can resist overload load and has a certain damping and buffering effect, and the robustness can enhance the usability of the attitude sensor in use.

Drawings

Fig. 1 is a schematic structural diagram of an attitude sensor based on a flexible optical waveguide according to an embodiment of the present invention;

fig. 2 is a schematic diagram of an operating principle of a flexible optical waveguide-based attitude sensor according to an embodiment of the present invention;

fig. 3 is a schematic diagram illustrating a relationship between an optical loss signal strength and a sine value of an included angle of a slope of an attitude sensor based on a flexible optical waveguide according to an embodiment of the present invention.

Wherein reference numerals in the drawings are illustrated as follows:

10. an attitude sensor; 100. an optical waveguide; 200. a frame; 210. a base; 220. a mounting seat; 230. a column; 300. a weight; 400. a slide rail; 500. a slider; 600. a first mounting member; 700. a force transfer member; 800. a second mount; 20. a bevel.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention more comprehensible, embodiments accompanying figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and are not to be considered limiting of the invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the present invention, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

It will be understood that when an element is referred to as being "secured to" or "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and the like as used herein are for illustrative purposes only and do not denote a unique embodiment.

In view of the above, an embodiment of the present invention provides a flexible optical waveguide-based attitude sensor 10, as shown in fig. 1, the flexible optical waveguide-based attitude sensor 10 including: optical waveguide 100, chassis 200, and weight 300; the optical waveguide 100 is disposed on the chassis 200, and the weight 300 is slidably disposed on the chassis 200 in a predetermined direction, the predetermined direction being perpendicular to an axis of the inner core of the optical waveguide 100 and parallel to a surface of the cladding of the optical waveguide 100, and the weight 300 is further connected to a surface of the cladding of the optical waveguide 100 and corresponds to the inner core of the optical waveguide 100.

Regarding the structure of the optical waveguide 100, as an example, the optical waveguide 100 includes: cladding, inner core, photoelectric element and circuit; the cladding is used for wrapping the inner core, the photoelectric element and the circuit, and the photoelectric element and the circuit comprise a light emitting diode, a light source power supply circuit, a photoelectric triode and a signal acquisition circuit. The cladding and the inner core of the optical waveguide 100 are both flexible materials with refractive indexes satisfying the total reflection of the optical waveguide, wherein the refractive index of the inner core material of the optical waveguide 100 is higher than that of the cladding material of the optical waveguide 100, for example, the cladding material of the optical waveguide 100 may be silicon rubber, and the inner core of the optical waveguide 100 may be polyurethane or polyacrylate. In addition, the shape of the inner core is linear, and the linear inner core not only facilitates the manufacture of the inner core, but also can more easily satisfy the total reflection requirement of the optical waveguide 100.

The working principle of the optical waveguide 100 described above can be described as follows: the light source power supply circuit supplies power to the light emitting diode and converts electric energy into light energy; original optical signals sent by the light-emitting diode are transmitted in the inner core, when force stimulation acts on the inner core, the inner core deforms, so that the original optical signals in the inner core are attenuated and become lossy optical signals, the lossy optical signals are detected by the phototriodes arranged at the tail end of the inner core, and the lossy optical signals are converted into analog electrical signals at the positions; the signal acquisition circuit captures an analog electric signal sent by the photoelectric triode, finally, the analog electric signal is sent to external equipment (such as a wireless receiving module), the external equipment receives, records and analyzes the analog electric signal, and original force stimulation information is decoded and restored through operations of linear interpolation, a neural network and the like.

For example, if the sensing of the one-dimensional posture is implemented, the posture change of the optical waveguide 100 along a defined angular direction (i.e., a preset direction) can be sensed, and the posture change in two other perpendicular directions in space is insensitive, at this time, an inner core may be disposed in the optical waveguide 100, and at this time, the weight 300 may be disposed at a position right above an axis of the inner core, so that when the weight 300 drives the optical waveguide 100 to move, the maximum displacement may be detected by the inner core, and the sensitivity of the optical waveguide 100 is improved; if 2 inner cores are arranged in the optical waveguide 100 to realize the sensing of the two-dimensional posture, the 2 inner cores are crossed in a cross shape, and correspondingly, the weight 300 is arranged at a position right above the axes of the two inner cores and can slide in two vertical preset directions in a plane. Of course, two optical waveguides 100 capable of realizing one-dimensional attitude sensing may be directly vertically disposed to realize two-dimensional attitude sensing. The working principle and structure of the attitude sensor 10 will be described below by taking an example in which an inner core is provided in the optical waveguide 100.

To describe the sensitivity of the attitude sensor 10 to the attitude tilt angle, referring to fig. 2, the attitude sensor 10 is fixed to a slope 20 having a tilt angle θ. The working principle of the attitude sensor 10 can be described as follows: the optical waveguide 100 of the attitude sensor 10, as a sensitive element, is capable of responding to a varying tangential force acting on its surface (i.e., G × sin θ shown in fig. 2, G being the gravity of the weight 300). And the weight force of the weight 300 will generate a component perpendicular to the surface of the optical waveguide 100 (i.e., G × cos θ shown in fig. 2) and a component parallel to the surface of the optical waveguide 100 (i.e., G × sin θ shown in fig. 2) that vary with the posture on the surface of the optical waveguide 100, wherein since the weight 300 is slidably disposed on the housing 200 only in a predetermined direction, the component acting perpendicular to the surface of the optical waveguide 100 is kept constant, and there is no constraint on the portion of the component parallel to the surface of the optical waveguide 100. Then as the attitude sensor 10 gradually increases from the horizontal home position to the attitude angle along the defined angular direction, the component force of the weight 300 parallel to the surface of the optical waveguide 100 gradually increases, and the response of the optical waveguide 100 gradually increases, and is linearly related to the magnitude of the force, i.e., in a sine-increasing relationship with the attitude angle (see fig. 3). In fig. 3, "forward travel" means that the inclination angle θ of the slope gradually increases from 0 ° to 90 °, and "backward travel" means that the inclination angle θ of the slope gradually decreases from 90 ° to 0 °.

In the attitude sensor 10 based on the flexible optical waveguide as described above, the weight 300 is slidably disposed on the frame 200 only in a predetermined direction, which enables the optical waveguide 100 to sense an absolute attitude by a gravity component of the weight 300, and compared with a gyroscope which senses an attitude by means of angular velocity integration, the absolute attitude is sensed without an integration process and an accumulated error problem caused by the integration process; because the sliding direction of the weight 300 is perpendicular to the axis of the inner core and parallel to the surface of the cladding, the output of the optical waveguide 100 has a good linear relation with the sine value of the attitude angle, and the optical waveguide has convenience in use and ensures the detection sensitivity; a flexible material is adopted as a sensitive unit (namely, the optical waveguide 100), and the flexible material has large deformation even under the action of a tiny force, namely, the flexible material has an amplification effect on the force, so that the attitude sensor 10 has high sensitivity; the optical waveguide 100 has robustness, and the optical waveguide 100 as a sensitive unit not only can resist overload load, but also has a certain shock absorption and buffering effect, and the robustness can enhance the usability of the attitude sensor 10 in use.

As shown in fig. 1, in some embodiments of the present invention, a slide rail 400 is disposed on the frame 200, and a slide block 500 capable of sliding in a predetermined direction is disposed on the slide rail 400, and the slide block 500 is connected to the weight 300. Through the cooperation of the slide rail 400 and the slider 500, it is possible to realize that the weight 300 can only slide in a preset direction, and also to simplify the structure of the attitude sensor 10.

As an example of how the slider 500 is engaged with the slide rail 400, the cross-sectional shape of the slide rail 400 is T-shaped, the slider 500 is provided with a T-shaped slide groove, and the slide rail 400 is inserted into the slide groove of the slider 500 to slide the slider 500 along itself.

Alternatively, the sliding rail 400 may be disposed on the frame 200 by welding, screwing, snapping, or the like.

Further, in some embodiments of the present invention, as shown in fig. 1, the posture sensor 10 further includes a first mount 600, and the first mount 600 is connected between the slider 500 and the weight 300. The first mounting member 600 facilitates the coupling of the slider 500 to the weight 300.

Alternatively, the first mounting member 600 may be a plastic member, which may be manufactured and processed by additive manufacturing. The first mounting member 600 may be mounted on the slider 500 by means of screws, bonding, or fastening, and the first mounting member 600 may be connected to the weight 300 by means of bonding, screws, or interference fit, wherein the weight 300 may be a metal block.

As shown in fig. 1, in some embodiments of the present invention, the posture sensor 10 further includes a force-transmitting member 700, the force-transmitting member 700 is connected between the weight 300 and the cladding of the optical waveguide 100, the force-transmitting member 700 corresponds to the inner core of the optical waveguide 100, and the area of the side surface of the force-transmitting member 700 near the optical waveguide 100 is smaller than the area of the side surface of the weight 300 near the optical waveguide 100. It should be noted that the side of the force-transmitting member 700 close to the optical waveguide 100 refers to the side of the force-transmitting member 700 directly contacting the cladding of the optical waveguide 100; if the force transmission member 700 is not provided between the weight 300 and the cladding of the optical waveguide 100, the side of the weight 300 adjacent to the optical waveguide 100 is directly in contact with the cladding of the optical waveguide 100. The force-transmitting member 700 having a small size is provided between the weight 300 and the optical waveguide 100, so that the weight of the weight 300 can be concentrated on the optical waveguide 100 as much as possible, thereby increasing the sensitivity of the optical waveguide 100.

As for the connection manner of the force transmission member 700, as one manner, the force transmission member 700 may be connected to the cladding surface of the optical waveguide 100 by means of bonding, screws, interference fit, or the like.

Further, in some embodiments of the present invention, as shown in fig. 1, the posture sensor 10 further includes a second mounting member 800, and the second mounting member 800 is connected between the force-transmitting member 700 and the weight 300. The second mounting member 800 facilitates the connection of the force transfer member 700 to the weight 300.

Alternatively, the second mounting element 800 may be a plastic element, may be manufactured by additive manufacturing, and may be connected to the force transmitting element 700 and the weight 300 by bonding, screws, interference fit, or the like.

As shown in fig. 1, in some embodiments of the invention, the rack 200 comprises: a base 210, a mount 220, and a post 230 supporting the mount 220 above the base 210; the light guide 100 is disposed on the base 210, and the weight 300 is slidably disposed on the mount 220. The rack 200 with the structure is simple in structure and convenient to produce and manufacture. As an example, the slide rail 400 is provided on the mount 220.

As for the number of the pillars 230, as an example, 4 may be provided, each of the pillars 230 being provided between the base 210 and the corner of the mount 220.

Further, in some embodiments of the present invention, mount 220 is capable of sliding up and down upright 230. The weight 300 is leveled on the surface of the optical waveguide 100 by moving the mounting base 220 up and down and the initial pre-stress of the weight 300 on the optical waveguide 100 is controlled.

Specifically, in some embodiments of the present invention, as shown in fig. 1, the upright 230 is a threaded rod, and the frame 200 further comprises a nut threadedly coupled to the upright 230 for locking the mount 220 at any height. It is understood that the mounting seat 220 is provided with a through hole for the upright 230 to pass through. As an example, each upright 230 is provided with two nuts, and when the mounting base 220 reaches a preset height, the mounting base 220 is clamped by the two nuts in cooperation with the screws, so as to lock the mounting base 220.

Another embodiment of the invention provides a robot comprising an attitude sensor 10 as defined in any one of the above.

As an example, the robot may be a mobile robot or a robot arm.

In order to describe the sensitivity of the attitude sensor 10 of the robot to the attitude tilt angle, referring to fig. 2, the attitude sensor 10 is fixed to a slope 20 having a tilt angle θ. The working principle of the attitude sensor 10 can be described as follows: the optical waveguide 100 of the attitude sensor 10 functions as a sensitive element that is capable of responding to a varying tangential force acting on its surface (i.e., G × sin θ shown in fig. 2, G being the gravity of the weight 300). And the weight force of the weight 300 will generate a component perpendicular to the surface of the optical waveguide 100 (i.e., G × cos θ shown in fig. 2) and a component parallel to the surface of the optical waveguide 100 (i.e., G × sin θ shown in fig. 2) that vary with the posture on the surface of the optical waveguide 100, wherein since the weight 300 is slidably disposed on the housing 200 only in a predetermined direction, the component acting perpendicular to the surface of the optical waveguide 100 is kept constant, and there is no constraint on the portion of the component parallel to the surface of the optical waveguide 100. Then as the attitude sensor 10 gradually increases from the horizontal home position to the attitude angle along the defined angular direction, the component force of the weight 300 parallel to the surface of the optical waveguide 100 gradually increases, and the response of the optical waveguide 100 gradually increases, and is linearly related to the magnitude of the force, i.e., in a sine-increasing relationship with the attitude angle (see fig. 3).

As described above, in the mobile robot, the weight 300 of the attitude sensor 10 is slidably disposed on the frame 200 only in a predetermined direction, which enables the optical waveguide 100 to sense an absolute attitude by a gravity component of the weight 300, and compared with a gyroscope which senses an attitude by an angular velocity integral, the absolute attitude is sensed, and there is no integral process and an accumulated error problem caused by the integral process; because the sliding direction of the weight 300 is perpendicular to the axis of the inner core and parallel to the surface of the cladding, the output of the optical waveguide 100 has a good linear relation with the sine value of the attitude angle, and the optical waveguide has convenience in use and ensures the detection sensitivity; the flexible material is adopted as the sensitive unit (i.e. the optical waveguide 100), and the flexible material has large deformation even under the action of a tiny force, namely, has an amplification effect on the force, so that the attitude sensor 10 has high sensitivity; the optical waveguide 100 has robustness, and the optical waveguide 100 as a sensitive unit not only can resist overload load, but also has a certain shock absorption and buffering effect, and the robustness can enhance the usability of the attitude sensor 10 in use.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. A flexible optical waveguide based attitude sensor, characterized in that the attitude sensor (10) comprises: an optical waveguide (100), a chassis (200), and a weight (300);

the optical waveguide (100) is arranged on the rack (200), the weight (300) is arranged on the rack (200) in a sliding mode along a preset direction, the weight (300) is further connected with the surface of the cladding of the optical waveguide (100) and corresponds to the inner core of the optical waveguide (100), and the preset direction is perpendicular to the axis of the inner core of the optical waveguide (100) and parallel to the surface of the cladding of the optical waveguide (100).

2. The attitude sensor according to claim 1, wherein the number of inner cores of the optical waveguide (100) is 1, and the shape of the inner core of the optical waveguide (100) is a straight line.

3. The attitude sensor according to claim 1, wherein a slide rail (400) is provided on the frame (200), and a slider (500) slidable in the predetermined direction is provided on the slide rail (400), the slider (500) being connected to the weight (300).

4. The attitude sensor according to claim 3, wherein the attitude sensor (10) further comprises a first mount (600), the first mount (600) being connected between the slider (500) and the weight (300).

5. The attitude sensor according to claim 1, wherein the attitude sensor (10) further comprises a force-transmitting member (700), the force-transmitting member (700) being connected between the weight (300) and the cladding of the optical waveguide (100), the force-transmitting member (700) corresponding to the inner core of the optical waveguide (100), the area of the side of the force-transmitting member (700) adjacent to the optical waveguide (100) being smaller than the area of the side of the weight (300) adjacent to the optical waveguide (100).

6. The attitude sensor according to claim 5, wherein the attitude sensor (10) further comprises a second mounting member (800), the second mounting member (800) being connected between the force-transmitting member (700) and the weight (300).

7. The attitude sensor according to any one of claims 1 to 6, wherein the gantry (200) comprises: a base (210), a mount (220), and a column (230) supporting the mount (220) above the base (210);

the optical waveguide (100) is disposed on the base (210), and the weight (300) is slidably disposed on the mount (220).

8. The attitude sensor according to claim 7, wherein the mount (220) is slidable up and down along the pillar (230).

9. The attitude sensor according to claim 8, wherein the upright (230) is a screw, and the frame (200) further comprises a nut threadedly coupled to the upright (230) for locking the mount (220) at any height.

10. A robot, characterized in that the robot comprises a flexible light guide based attitude sensor (10) according to any of claims 1-9.