JPS62221856A - Spherical motor - Google Patents

Abstract

PURPOSE:To miniaturize and lighten a multi-degree-of-freedom actuator by arranging plural sets of windings on a spherical surface and controlling an electric current of each winding. CONSTITUTION:A spherical motor is composed of a rotor 3 having spherical magnetic poles on the outer periphery by the use of a permanent magnet 1 and a yoke 2, a stator 8 having slots provided with winding groups 4-7 and a spherical bearing 11 rotatably supporting an output shaft 10 united in an integral body with the rotor 3 at three degrees of freedom. In this manner, a torque T about three axes X, Y, Z can freely be controlled by adjustment of an electric current of four windings according to the inclinations theta, phi of the output shaft 10.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a multi-degree-of-freedom actuator used in a multi-degree-of-freedom movement mechanism such as a manipulator, and in particular realizes movement in three degrees of freedom with a small and simple structure. This invention relates to the configuration of a spherical motor.

[Conventional technology]

When configuring a multi-degree-of-freedom mechanism, one actuator is generally arranged for one degree of freedom.

Motion with multiple degrees of freedom is achieved using a complex transmission mechanism. For this reason, problems arise in that the mechanical positioning accuracy deteriorates due to the influence of elastic deformation and play in the transmission mechanism, and that the entire mechanism becomes large and heavy.

Further, the weight of the actuator at the tip becomes a load on the actuator at the base, and it is often necessary to use an actuator that is larger than necessary for the actual load.

On the other hand, if the actuator itself can have multiple degrees of freedom,
These problems can be solved, and the mechanism can be simplified, made smaller, and lighter.

[Problem that the invention seeks to solve]

Currently, the majority of motors on the market are of the one-degree-of-freedom type, either rotating or linear. A typical example of a conventional multi-degree-of-freedom actuator is an XY-shaped planar step motor based on the Sa%tyer principle, which is actually used in an automatic drafting machine developed by XYNETIC8. Further, research is progressing on linear motor induction motors for two-way conveyance, cylindrical step motors that drive in two directions (straight motion and rotation), etc., but these have not yet been put to practical use. On the other hand, for three-degree-of-freedom types, three-dimensional motors that utilize rotational fields and spherical actuators that use functional materials such as shape memory alloys and electrostrictive elements have been proposed. All of these ideas are still on the idea ladder and have not yet been materialized.

The purpose of the present invention is to realize a multi-degree-of-freedom actuator that is necessary for simplifying the multi-degree-of-freedom mechanism and reducing its size and weight. The purpose is to provide a spherical motor.

[Means and effects for solving the problem] The spherical motor according to the present invention has multiple sets of windings arranged on a spherical surface and controls the current of each winding, thereby adjusting the rotor to torque around three orthogonal axes. It is characterized by a structure that allows it to occur freely.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a structural sectional view showing one embodiment of the spherical motor of the present invention, and FIG. 2 is a sectional view taken along the line AA' in FIG. In the figure, 1 is a permanent magnet, and 2 is a yoke. The permanent magnet 1 and the yoke 2 constitute a rotor 3 having spherical magnetic poles on the outer periphery. 4 to 7 are winding groups, and these winding groups are made up of multiple sets of windings. One set of windings covers 4 hemispheres.
It consists of four divided windings, and in Fig. 2, four sets of windings a" and d are shown. 8 is a stator having slots in which windings 4 to 7 are installed. 3 = Yes, the rotor 3 and \ form a magnetic path as indicated by the dotted line 9 in the figure. 10 is the output shaft integrated with the rotor 3,
One end thereof is rotatably supported via a spherical bearing 11. FIG. 3 is a diagram showing the structure of the windings 4 to 7 in FIG. 2, in which four sets of windings a'' d constituting the winding groups 4 to 7 are arranged slightly offset from each other.

FIG. 4 is a diagram for explaining the operation of the spherical motor of the present invention, and FIG. 5 shows the positional relationship between the rotor and the stator.

Next, the operation of the present spherical motor will be explained according to FIG. In the figure, 4a to 7a are a set of windings shown in FIG. Further, a dotted line 12 indicates the outer peripheral portion of the rotor 3, and indicates a position where the magnetic field acts. At this time,
Intersections 13a to 13d between the dotted line 12 and the windings 4a to 7a are points of application of force.

Therefore, we take a rectangular coordinate system xYz fixed to the stator with the center 0 of the spherical surface formed by one winding as the origin, and the position vectors of the force application points 13a to 13d in that coordinate system are expressed as r1 to
r 4 + Also, the force vector acting on each point of application is f□
~ f4, the torque T around the three axes of XYZ is the first
It is given by Eq.

Tazoshi, τ8. τ9. τ2 is the X axis of torque T,
It shows the torque components around the Y-axis and two axes.

At this time, the magnitude of the force f□~f4 generated at each point of application is determined by the magnetic flux density B at each point and the current i□~i that crosses the magnetic field at that point.
It is a well-known fact that it is determined by the size of 4, and is given by, for example, the second equation.

Ifll=NβB (i□-12) (2)
where N is the number of windings and Q is the length that the windings cross the magnetic field. Therefore, the values of f1 to f4 can be arbitrarily adjusted by the values of the four winding currents i to i4.

Further, r1 to r4 can be determined geometrically using the inclination angle (for example, Euler angle) of the output shaft. for example,
The Z PI axis shown in Figure 5 is the output shaft 10, the inclination angle of this 2'' axis is the rotation angle θ around the X axis, and the rotation angle around the Y' axis of the x'y'z' coordinate system after this rotation. rotation angle φ
Then, r-r4 is expressed as a function h□ of O and φ, as shown in the third equation.

In addition, Xi,yj+Zj indicates the XYZ components of the position vector r.

Using the first to third equations above, τ8 becomes as shown in the fourth equation.

τ8=Z2f2-24f4 =NnB(zz"bz 13) Z4'(14xx
)) (4) Similarly, τ9. Regarding τ2, the fifth and sixth equations are obtained.

ry=NQB (za-(i4-ia)-Zl・(i2
-il)) (5)τZ=NQB (X4”(14i
t) Xi” (121a)) 10Nl1B (yt・(
1211) 3'a·(j+-1a)) (6) As explained earlier, Xjs yjy Zj is given as a function of θ and φ. Therefore, the inclination angle of the output shaft is 0. φ
By adjusting the four winding currents 10 to i4 according to
It becomes possible to freely control the torque T around the Z3 axis.

However, as shown in Fig. 3, multiple sets of such windings (4a to 7a, 4b to 7b, 4c to
7c, 4d to 7d), and by switching the exciting winding based on the displacement around the Z axis, it is possible to rotate smoothly and infinitely around the two axes.

It goes without saying that the above operation is exactly the same even if the winding is provided on the rotor side and the permanent magnet or spherical magnetic pole made of a permanent magnet and a yoke is provided on the stator side.

FIG. 6 shows another embodiment of the spherical motor of the present invention, which is provided with means for detecting the relative position of the rotor and stator.

In the figure, 14 is a spherical sliding bearing, 15 is a rotating bearing, 16 is a support member, 17 is an optical encoder for detecting rotation, and 18 is a leaf spring with a strain gauge attached to the surface for detecting the inclination of the output shaft 10. It is. This leaf spring 18 is provided between the stator 8 and the support member 16 via a spherical sliding bearing 14, and the optical encoder 17 is provided between the support member 16 and the output shaft 10 with a rotary shaft 15 between the support member 16 and the output shaft 10. provided through. 2 like this
By having a multilayer structure, the tilt angle O2φ of the output shaft and the rotation of the output shaft can be detected separately, and furthermore, the current in each winding can be controlled according to the tilt angles θ and φ of the output shaft. This makes it possible to compensate for fluctuations in drive torque due to the inclination of the output shaft.

〔Effect of the invention〕

As described in detail above, according to the spherical motor having the structure according to the present invention, it is possible to easily realize a spherical motor with three degrees of freedom with a relatively simple structure. can.

[Brief explanation of drawings]

Fig. 1 is a diagram showing an embodiment of the spherical motor of the present invention, Fig. 2 is a sectional view taken along the line AA' in Fig. 1, Fig. 3 is a structural diagram of the windings in the spherical motor shown in Fig. The figure is an operating principle diagram for explaining the operation of the spherical motor of the present invention, Figure 5 is an explanatory diagram defining the inclination of the output shaft, and Figure 6 is a partial cross section of another embodiment of the spherical motor of the present invention. It is a diagram. DESCRIPTION OF SYMBOLS 1... Permanent magnet, 2... Yoke, 3... Rotor, 4a-7d... Spherical winding, 8... Stator,
9... Magnetic path, 10... Output shaft, 11...
Spherical bearing, ], 3 a to 13 d... point of force application,
14... Spherical sliding bearing, 15... Rotating bearing,
16... Support member, 17... Rotary encoder, 18... Leaf spring. Fig. 1 Fig. 2 Fig. 9 5g 4i - 87+, 71.4c / ゛ 1 permanent a (6s"", 4. - N215, -3 Sa" 61 0 Kua Perak b X Village

Claims (3)

[Claims] (1) A stator having a plurality of windings arranged on a spherical surface in a shape that divides the spherical surface into a plurality of parts, a rotor having spherical magnetic poles made of a permanent magnet or a permanent magnet and a yoke, and the rotor as described above. It has a stator and a spherical bearing rotatably supported through a microgap, and by controlling the current flowing through each winding of the stator in the magnetic field generated from the permanent magnet of the rotor, the rotor can be rotated in any direction. A spherical motor characterized by generating driving torque. (2) A spherical motor according to claim 1, characterized in that a winding is provided on the rotor side and a spherical magnetic pole made of a permanent magnet or a permanent magnet and a yoke is provided on the stator side. motor. (3) In the spherical motor according to claim 1 or 2, a means for detecting a three-dimensional position signal of the rotor is provided, and the current supplied to each winding is switched in accordance with the position signal. A spherical motor featuring