COMPACT BIONIC EYE DEVICE BASED ON TWO-DEGREE-OF-FREEDOM ELECTROMAGNETICALLY-DRIVEN ROTATING MECHANISM

Abstract

The present disclosure provides a compact bionic eye device based on a two-degree-of-freedom electromagnetically-driven rotating mechanism, which can be used as a vision sensor of bionic robots such as humanoid robots. The compact bionic eye device includes a rotor, stator cores, windings, an angular displacement camera, a spherical hinge pressing block, a stator connector, a camera, a spherical hinge, a camera connector, a rotor connector and an outer spherical shell. According to the compact bionic eye device of the present disclosure, the rotor is driven to achieve limited rotation with pitching and yawing degrees of freedom by regulating a current of the windings of four stators. By adopting a two-degree-of-freedom of electromagnetically-driven rotating mechanism which is compact in structure, the bionic eye device of the present disclosure can achieve a human eye size, and provides important foundation for practical application of bionic eyes in humanoid robots.

Claims

1. A compact bionic eye device based on a two-degree-of-freedom electromagnetically-driven rotating mechanism, being composed of a stator assembly and a rotor assembly, wherein the stator assembly comprises an outer spherical shell (2), stator cores (3), a stator connector (5), an angular displacement camera (6), a spherical hinge pressing block (9) and windings (10); and the rotor assembly comprises a camera (1), a rotor (4), a rotor connector (7), a spherical hinge (8) and a camera connector (11); four stator cores (3) are fixedly connected with the outer spherical shell (2) and uniformly distributed along the large circumference of the outer spherical shell (2); the stator connector (5) is located at the central position of the four stator cores (3) and used for connecting and fixing the four stator cores (3); the rotor connector (7), the spherical hinge (8) and the camera connector (11) form a transmission rod; the center of the spherical hinge (8) is concentric with the center of a central spherical surface of the rotor (4) and restrains the rotor assembly to rotate around a fixed-point, i.e., around the center of the central spherical surface of the rotor (4); the spherical hinge pressing block (9) and the stator connector (5) are arranged at both sides of spherical hinge (8), close to the camera and the rotor respectively; and in this way, a sphere pair is formed by the spherical hinge (8), the spherical hinge pressing block (9) and the stator connector (5).

2. The compact bionic eye device based on a two-degree-of-freedom electromagnetically-driven rotating mechanism according to claim 1, wherein the rotor (4) is of a quartered structure like a hemispherical shell; the section formed by each quadrant segment being cut by any plane with fixed axis is a sector ring; the fixed axis, in symmetry plane of a quadrant segment and its opposite one, is the only straight line parallel to the end-face circle of the rotor; a width of the sector ring of the section is 2d and d=d.sub.max−η.sub.d θ/θ.sub.max, wherein θ represents an included angle of a cutting surface and a symmetry surface, d.sub.max represents half the width of the sector ring of the section when θ is equal to 0, θ.sub.max represents a maximum value of θ, and η.sub.d is a constant that represents that the width of the sector ring of the section decreases with an increase of θ.

3. The compact bionic eye device based on a two-degree-of-freedom electromagnetically-driven rotating mechanism according to claim 1, wherein the stator cores (3), the rotor (4) and the windings (10) form four double-gap electromagnets, each stator core (3) corresponds to one quadrant segment of the rotor (4), the surface of each stator pole is parallel to the surface of the rotor; and the stator cores (3) and the rotor (4) are both made from a magnetic material.

4. The compact bionic eye device based on a two-degree-of-freedom electromagnetically-driven rotating mechanism according to claim 1, wherein every two opposite electromagnets are used to drive the rotor assembly to do a one-degree-of-freedom motion; and by regulating a current of the four windings (10), the rotor assembly can be driven to do a two-degree-of-freedom motion including positive/negative pitching and positive/negative yawing, respectively.

5. The compact bionic eye device based on a two-degree-of-freedom electromagnetically-driven rotating mechanism according to claim 1, wherein the angular displacement camera (6) is used for acquiring a feature image of the bottom of the rotor; and the acquired image can be processed to calculate an actual rotating angle, namely a yawing angle and a pitching angle of the rotor assembly.

6. The compact bionic eye device based on a two-degree-of-freedom electromagnetically-driven rotating mechanism according to claim 1, wherein the compact bionic eye device can be combined with a close-loop controller to control angle of the rotor assembly: based on difference between an actual angle and a specified one, a regulation value of the current of each winding (10) is calculated, so that the current of the windings (10) is regulated to drive the rotor assembly, and the actual angle tends to the specified one.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0013] FIG. 1 is a structural diagram of a compact bionic eye device based on a two-degree-of-freedom electromagnetically-driven rotating mechanism of the present disclosure.

[0014] FIG. 2 is a three-dimensional diagram of the interior of the compact bionic eye device based on a two-degree-of-freedom electromagnetically-driven rotating mechanism of the present disclosure.

[0015] FIG. 3 is a flow diagram of a control system of the compact bionic eye device based on a two-degree-of-freedom electromagnetically-driven rotating mechanism of the present disclosure.

[0016] FIG. 4 shows results of finite element analysis of an electromagnetic field of a magnetic circuit of one electromagnet of the compact bionic eye device based on a two-degree-of-freedom electromagnetically-driven rotating mechanism of the present disclosure.

DETAILED DESCRIPTION

[0017] FIG. 1 shows the structural diagram of the compact bionic eye device, where the overall compact bionic eye device consists of a stator assembly and a rotor assembly. The stator assembly includes an outer spherical shell 2, stator cores 3, a stator connector 5, an angular displacement camera 6, a spherical hinge pressing block 9 and windings 10. The rotor assembly includes a camera 1, a rotor 4, a rotor connector 7, a spherical hinge 8 and a camera connector 11. The four stator cores 3 are fixedly connected with the outer spherical shell 2 and uniformly distributed along the large circumference of the outer spherical shell 2. The stator connector 5 is located at the central position of the four stator cores 3 and used for connecting and fixing the four stator cores 3. The rotor connector 7, the spherical hinge 8 and the camera connector 11 form a transmission rod. The center of the spherical hinge 8 is concentric with the center of a central spherical surface of the rotor 4, and restrains the rotor assembly to rotate around a fixed-point, i.e., around the center of the central spherical surface of the rotor 4. The spherical hinge pressing block 9 and the stator connector 5 are arranged at both sides of spherical hinge 8, close to the camera and the rotor respectively. In this way, a sphere pair is formed by the spherical hinge 8, the spherical hinge pressing block 9 and the stator connector 5.

[0018] The rotor 4 shown in FIG. 1 is of a quartered structure like a hemispherical shell. The section formed by each quadrant segment being cut by any plane with fixed axis is a sector ring. The fixed axis, in symmetry plane of a quadrant segment and its opposite one, is the only straight line parallel to the end-face circle of the rotor 4. The width of the sector ring of the section is 2d. According to the requirements of a human eye size, the diameter of the outer spherical shell 2 is 24 mm: the radius of the central spherical surface of the rotor 4 is 7.5 mm; if θ represents an included angle of a cutting surface and a symmetry surface, when θ is equal to 0, d.sub.max=0.8 mm, namely half the width of the sector ring of the section; the maximum value θ.sub.max of θ is equal to 86 degrees; a constant representing that the width of the sector ring of the section decreases with an increase of θ is η.sub.d which is equal to 0.215; and accordingly d=0.8-0.215θ/86 (mm).

[0019] FIG. 2 shows the three-dimensional diagram of the interior of the compact bionic eye device, where the stator cores 3, the rotor 4 and the windings 10 form four double-gap electromagnets, where each stator core 3 corresponds to one quadrant segment of the rotor 4. Moreover, the surface of each stator pole is parallel to the surface of the rotor 4. The stator cores 3 and the rotor 4 are both made from a magnetic material. Every two opposite electromagnets are used to drive the rotor assembly to do a one-degree-of-freedom motion. By regulating the current of the four windings 10, the rotor assembly can be driven to do a two-degree-of-freedom motion including positive/negative pitching and positive/negative yawing, respectively.

[0020] FIG. 3 shows the flow diagram of the control system of the bionic eye device, where the compact bionic eye device can be combined with a close-loop controller to control angle of the rotor assembly. Based on difference between the actual angle and specified one, a regulation value of the current of each winding 10 is calculated, so that the current of the windings 10 is regulated to drive the rotor assembly, and the actual angle tends to the specified one. The angular displacement camera 6 is used for taking a feature image of the bottom of the rotor, and the image can be processed to calculate an actual rotating angle, namely a yawing angle and a pitching angle of the rotor.

[0021] When the rotor 4 of the bionic eye rotates 30 degrees about axis x, electromagnetic field finite element analysis is performed with respect to magnetic circuit of a +y electromagnet causing the rotation, and the results are shown in FIG. 4, where electromagnetic forces in axis x, axis y and axis z are 0.66231×10.sup.−3 N, 0.21417×10.sup.−2 N, 0.20977×10.sup.−2 N respectively: the driving torque around axis x is 0.22484×10.sup.−4 Nm; and an angular acceleration that can be provided is as high as 153.91 rad/s.sup.−2.

[0022] The content not described in detail in the description is existing technologies known by those skilled in the art.