JP2003065416A - Two degree-of-freedom actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a two degree-of-freedom actuator embodied at a low cost in a small and lightweight construction. SOLUTION: The two degree-of-freedom actuator includes one shaft which can perform a rotational motion and stroke motion independently and is equipped with two rotary motors 2 and 8 and one ball screw 17, whereby the motors 8 and 2 conduct rotational control of the nut 18 and shaft 19 of the ball screw 17, respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-degree-of-freedom actuator referred to as, for example, a .theta.-Z motor or the like, in which the same shaft can independently perform rotational movement (.theta.) And stroke movement (Z). .

[0002]

2. Description of the Related Art An example of a conventional 2-DOF actuator is shown in FIG. The conventional two-degree-of-freedom actuator 21 is configured by combining one rotary motor 22 and one linear motor 23. The rotary motion (θ) is taken by the rotary motor 22 and the stroke motion (Z) is linear. The motor 23 is in charge. In FIG. 2, reference numeral 24 is a frame of the rotary motor 22, and a load side end portion is a bracket 25.
And the end portion on the side opposite to the load is fitted to the bracket 26. A cylindrical linear guide support portion 27 is attached to the bracket 26. A stator 28 of the rotary motor 22 has a stator core 29 and a stator winding 30. Reference numeral 31 denotes a rotor of the rotary motor 22, which is provided on an outer peripheral surface of a first linear guide 33 which is rotatably supported by the linear guide support portion 27 and the bracket 25 via a bearing 32. A second linear guide 34 is attached to the inner peripheral surface of the linear guide support portion 27.
Reference numeral 35 denotes a shaft as an output shaft that is fitted and supported by the first and second linear guides 33 and 34, and forms a spline or the like on the outer peripheral surface of the load side portion that is in contact with the first linear guide 33. A cup-shaped mover support 36 is attached to the end of the shaft 35 on the side opposite to the load via a bearing. A mover 37 is attached to the outer peripheral surface of the cylindrical portion of the mover support 36. 38 is the linear motor 2
In the frame No. 3, the load side end is fitted and attached to the bracket 26. Reference numeral 39 denotes an armature winding of the linear motor 23, which faces the mover 37 via a radial gap. 40 is a frame 38 of the linear motor 23
A linear scale 41 attached to the moving body support 36 is attached to the moving body support 36. Reference numeral 42 denotes a shaft drop prevention device, which is attached to the frame 38. The shaft is supported so that it can move freely in the linear direction in the first guide 33, but is locked in the rotational direction so that it cannot move, and it moves in the linear direction in the second linear guide 34. Is also supported so that it can move freely in the direction of rotation. In such a configuration, the rotational movement (θ) of the shaft 35 is performed by using the rotary motor 22. That is, when the rotary motor 22 is driven, the rotor 31 rotates. The rotation of the rotor 31 causes the first linear guide 33 to rotate. When the first linear guide 33 rotates, the shaft 35 rotates together with the first linear guide 33. As a result, the rotational movement of the shaft 35 is performed. In addition, the shaft 35
The stroke motion (Z) is performed using the linear motor 23. That is, when the linear motor 23 is driven, the mover 37 moves in the linear direction. When the mover 37 moves in the linear direction, the shaft 35 moves together with the mover support 36 in the linear direction. As a result, the stroke movement of the shaft 35 is performed. When the rotary motor 22 and the linear motor 23 are driven at the same time, the shaft 35 makes a stroke motion while rotating. In addition, in this configuration, both the rotary motor 22 and the linear motor 23 are in the non-driven state.
Since there is no force to hold 5, l shaft 35
In the case of holding, the shaft drop prevention device 42 is operated.

[0003]

However, such a conventional two-degree-of-freedom actuator has the following problems. (1) In stroke motion, a linear scale for position detection is required to perform position control, which increases the size of the device. Also, a linear scale with a length corresponding to the stroke amount must be used, but in the case of a non-standard length,
Each time, it must be created separately, which is costly and difficult to handle. (2) When the stroke motion is performed in the vertical direction, a force to hold the shaft when the motor is not driven is required, but there is no force to hold the shaft when the motor is not driven. Need to be installed, the structure is complicated and large. The present invention has been made to solve such a problem, and an object of the present invention is to provide a small, lightweight, inexpensive two-degree-of-freedom actuator.

[0004]

In order to solve the above problems, the present invention provides a two-degree-of-freedom actuator in which the same shaft can independently perform a rotational movement and a stroke movement. It has a ball screw and one rotary motor has a ball screw nut.
The other rotary motor controls the rotation of the ball screw shafts.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a side view showing a two-degree-of-freedom actuator according to an embodiment of the present invention. The two-degree-of-freedom actuator of the present invention includes two rotary motors and one ball screw. The rotational movement (θ) is
The first rotary motor takes charge of the stroke motion (Z)
Is carried by the second rotary motor. In FIG. 2, 1 is a 2-DOF actuator, 2 is a first rotary motor that constitutes the 2-DOF actuator 1, 3 is a frame of the first rotary motor 2, and a stator 4 is attached to an inner peripheral surface thereof. ing. The stator 4 has a stator core 5 and a stator winding 6. Reference numeral 7 denotes a rotor arranged to face the stator 4 with a radial gap therebetween. Reference numeral 8 is a second rotary motor constituting the two-degree-of-freedom actuator 1, 9 is a frame of the second rotary motor 8, the load side end portion of which is an anti-load of the frame 3 of the first rotary motor 2. The stator 10 is attached to the inner peripheral surface while being fitted and fixed to the side end portion. The stator 10 has a stator core 11 and a stator winding 12. Reference numeral 13 is a cup-shaped rotor that is arranged to face the stator 10 with a gap in the radial direction therebetween. 1
4 is a load side bracket of the 2-DOF actuator 1,
The frame 3 of the first rotary motor 2 is provided at the end portion on the side opposite to the load.
The load side end of is fixedly fitted. Reference numeral 15 denotes an anti-load side bracket, and the anti-load side end portion of the frame 9 of the second rotary motor 8 is fitted and fixed to the load side end portion. The second
The rotor 13 of the rotary motor 8 is rotatably supported by the anti-load side bracket 15 via a bearing 16. Reference numeral 17 denotes a ball screw arranged in the two-degree-of-freedom actuator 1, which is the rotor 1 of the second rotary motor 8.
3, a ball screw nut 18 mounted inside the ball screw 3 and a ball screw shaft 19 as an output shaft screwed with the ball screw nut 18. The ball screw shaft 19 includes a load side bracket 14 on the load side.
Is supported via a linear guide 20, and the rotor 7 of the first rotary motor 2 is fitted and fixed to the outer peripheral surface. The linear guide 20 supports the ball screw shaft 19 so that the ball screw shaft 19 can move freely in both the rotational direction and the linear direction. In such a configuration, the rotational movement (θ) of the ball screw shaft 19 is performed by rotating the first rotary motor 2 and the second rotary motor 8 synchronously in the same rotation direction. That is, when the first rotary motor 2 is driven, the rotor 7 rotates. This rotation of the rotor 7 causes the ball screw shaft 19 integrated with the rotor 7 to rotate. In this case, since the ball screw shaft 19 is screwed with the ball screw nut 18, unless the ball screw nut 18 is also rotated together with the ball screw shaft 19, the ball screw shaft 19 will perform an unnecessary linear movement. Therefore, the second rotary motor 8 is rotated in the same rotation direction in synchronization with the first rotary motor 2 so that the ball screw shaft 19 does not move linearly. The stroke movement (Z) of the ball screw shaft 19 is stopped by the first rotary motor 2 to stop the rotation movement (θ) of the ball screw shaft 19.
This is performed by driving the second rotary motor 8 in this state. That is, when the second rotary motor 8 is driven,
The rotor 13 rotates. By the rotation of the rotor 13, the ball screw nut 1 integrated with the rotor 13
8 rotates. In this case, when the ball screw shaft 19 is fixed in the rotation direction, the ball screw nut 18 is rotated to cause the ball screw shaft 19 that is screwed into the ball screw nut 18 to make a linear motion. For example, the ball screw nut 18 and the ball screw nut 18 are rotated together, and the linear movement cannot be performed.
Therefore, the first rotary motor 2 is used for the ball screw shaft 1
The movement of 9 in the rotation direction is regulated. When rotating the ball screw shaft 19 while making a stroke motion, the first rotary motor 2 and the second rotary motor 8 are simultaneously driven. In this case, the amount of rotary motion (θ) is , The rotation amount of the first rotary motor 2,
The amount of stroke motion (Z) is equal to the difference in rotation between the second rotary motor 8 and the first rotary motor 2 times the ball screw pitch. As described above, according to the two-degree-of-freedom actuator of the present invention, since the stroke motion (Z) only converts the rotation into the linear motion by the ball screw, the rotation motion (θ) and the stroke motion (Z) are converted. Two actions are all 2
It is possible to control only by the rotation amount of one rotary type motor. Therefore, if the amount of rotation of the second rotary motor 8 can be grasped, the conventionally used linear scale becomes unnecessary. Further, since a constant shaft holding force can be obtained even when the motor is not driven, there is no need for a shaft fall prevention measure. Further, the thrust F in the stroke motion (Z) is given by the following equation,
Compared with the conventional linear motor system, much larger force can be obtained. F [N] = 2πηT / (L × 10 ⁻³ ) η: Ball screw efficiency T: Motor torque [N · m] L: Ball screw pitch [mm] In the present invention, the rotary motor is a stepping motor or AC. Not limited to the servo motor, any type of motor may be used.

[0006]

As described above, the present invention has the following effects. (1) The structure of the two-degree-of-freedom actuator can be greatly simplified, and a small, lightweight, inexpensive two-degree-of-freedom actuator can be provided. (2) The thrust in the stroke motion can be increased compared to the conventional linear motor method.

[Brief description of drawings]

FIG. 1 is a side sectional view showing a two-degree-of-freedom actuator according to an embodiment of the present invention.

FIG. 2 is a side sectional view showing a two-degree-of-freedom actuator in the related art.

[Explanation of symbols]

12 degree of freedom actuator, 2 first rotary motor, 3 frames, 4 stator, 5 Stator core, 6 stator winding, 7 rotor, 8 second rotary motor, 9 frames, 10 stator, 11 stator core, 12 stator windings, 13 rotors, 14 Load side bracket, 15 Anti-load side bracket, 16 bearings, 17 ball screws, 18 ball screw nuts, 19 ball screw shaft, 20 Linear guide

Claims (2)

[Claims] 1. A two-degree-of-freedom actuator in which the same shaft can independently perform a rotary motion and a stroke motion, comprises two rotary motors and one ball screw, and one rotary motor has a ball screw nut. ,
A two-degree-of-freedom actuator in which the other rotary motor controls the rotation of each ball screw shaft. 2. The two-degree-of-freedom actuator according to claim 1, wherein the rotor of the one rotary motor is formed in a cup shape, and a nut of a ball screw is attached inside.