JP4048857B2 - Rotation angle measuring device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rotation angle measurement device, and more particularly to a rotation angle measurement device that measures a rotation angle of a drive device that rotates a rotating component having a relatively large frictional resistance.
[0002]
[Prior art]
As a rotation angle measuring device, there is one that measures a rotation angle of a driving device for rotating a rotating component having a relatively large frictional resistance. This drive device is, for example, an automatic screw tightening device for assembling a product in which a gap (not shown) set by a screw rotation angle is fixed in a sealed container (not shown) that is screwed. There is an assembly machine. This type of rotational angle measuring device is a rotating body that rotates in synchronization with a drive shaft that rotates a screw of an automatic assembly machine, a measuring device base that rotatably supports the rotating body, and a rotational angle of the rotating body. A rotation angle measuring unit for measuring is provided.
[0003]
Note that the rotation angle of the automatic assembly machine that rotates in synchronization with the rotating body is measured by the rotation angle measuring unit measuring the rotation angle of the rotating body.
[0004]
[Problems to be solved by the invention]
In the conventional rotational angle measuring device, there is a possibility that it cannot sufficiently cope with a request for improvement in the gap accuracy of the product as compared with the conventional one. That is, when the measurement accuracy is required to be approximately the same as the elastic torsional deformation of products and devices due to the frictional resistance during screw tightening, the conventional rotation angle measuring device uses a highly accurate rotation angle of the screw tightening device. There may be a problem that measurement cannot be performed.
[0005]
The present invention has been made in view of such circumstances, and an object of the present invention is to provide a rotation angle measuring device capable of measuring the rotation angle with a frictional resistance with high accuracy.
[0006]
Another object of the present invention is to provide a rotation angle measuring device capable of increasing the accuracy for measuring the rotation angle of a driving device that rotates a rotating component having a relatively large frictional resistance.
[0007]
[Means for Solving the Problems]
According to the first aspect of the present invention, a driving device that generates a rotational driving force and a rotating component that protrudes rotatably from both ends of the driving device and is rotationally driven by the rotational driving force are connected to one end side, and the other end side is connected. A drive shaft provided with a rotator, a rotation angle measuring unit for measuring the rotation angle of the rotator, a resistance adding unit for applying a resistance force to the rotation of the rotator, a control means for driving and controlling the resistance adding unit, and rotation Rotational torque deriving means for deriving the rotational torque (T) due to the frictional resistance (Rf) of the component,
The control means adjusts the resistance force (Rr) applied to the rotating body by the resistance adding unit so that the resistance torque (Tr) is equal to the rotational torque (T) derived by the rotational torque deriving means .
[0011]
Thereby, the resistance adding unit can constitute a so-called disc brake. Therefore, the resistance adding portion can easily adjust the load that holds the rotating body, that is, the disk-shaped portion, that is, the predetermined resistance force.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments in which the rotation angle measuring device of the present invention is embodied will be described with reference to the drawings. FIG. 1 is a configuration diagram showing a configuration of a rotation angle measuring device according to an embodiment of the present invention. FIG. 3 is a graph showing the relationship between the rotation angle at the rotating component to be rotated, the rotation angle at the drive shaft of the measured object, and the rotation angle at the rotating body in the rotation angle measuring device of the present embodiment. 3A shows a case where a predetermined resistance force is applied to the rotating body by the resistance adding unit. FIG. 3B shows a case where the predetermined resistance force is rotated by a drag that cancels out the frictional resistance force generated in the rotating component. It is a graph which shows the case where it adds to a body. FIG. 2 is a configuration diagram showing the configuration of the rotation angle measuring device of the comparative example. Furthermore, FIG. 4 is a graph showing the relationship between the rotation angle at the rotating component to be rotated, the rotation angle at the drive shaft of the measured object, and the rotation angle at the rotating body in the conventional rotation angle measuring device. It is.
[0018]
As shown in FIG. 1, the rotation angle measuring device 1 is a measuring device that measures the rotation angle related to the rotation of the measured object 9 and has a frictional resistance caused by the rotation of the measured object. The rotation angle of the measuring body is measured.
[0019]
The object to be measured 9 is a manufacturing apparatus that manufactures a product having rotating parts, a rotational force generating apparatus such as a driving apparatus that rotates the object to be rotated, or a system including the rotational force generating apparatus, When rotating the object 100, the rotating object, for example, a screw part (not shown) as the rotating part 100 a constituting the product 100 is rotated against the so-called sliding frictional resistance generated when the screw is tightened. Any device may be used as long as it can cause elastic torsional deformation of at least the drive shaft portion 9a of the device.
[0020]
As shown in FIG. 1, the rotation angle measuring device 1 includes a rotating body 3, a rotating angle measuring unit 4 that measures the rotating angle of the rotating body 3, and a resistance adding unit that applies a resistance force to the rotation of the rotating body 3. 5. In addition, the rotary body 3 and the rotation angle measurement part 4 are supported by the installation base part 2, as shown in FIG. The rotating body 3 is rotatably supported by the mounting base 2.
[0021]
As shown in FIG. 1, the rotating body 3 can rotate in synchronization with a drive shaft portion 9 a of a drive device 9 as a rotational force generator that rotates a product 100 (specifically, a rotating component 100 a) to be rotated. In this way, it is connected to the drive device 9 (specifically, the drive shaft portion 9a). In other words, the rotating body 3 constitutes a part of the measured object 9. The details of the structure of the rotating body 3 will be described later.
[0022]
As shown in FIG. 1, the rotation angle measuring unit 4 is a measuring device that is engaged with or fixed to the rotating body 3 and measures the rotation angle of the rotating body 3, and is a known encoder or a plurality of outputs per rotation. A rotation angle sensor that outputs a signal (for example, 200 pulses) may be used. In addition, since the precision of the resolution as a basic characteristic of the rotation angle measuring unit 4 that detects the rotation angle is determined by the number of output signals output per rotation, the output that is output per rotation according to the desired required resolution. A rotation angle sensor with a desired number of signals may be used. Hereinafter, the rotation angle measurement unit 4 of the present embodiment will be described as an encoder.
[0023]
Here, as described above, since the rotating body 3 constitutes a part of the measurement target 9 (specifically, the drive shaft portion 9a), the following may generally occur. That is, when rotating the drive shaft portion 9a of the drive device 9 against the frictional resistance generated by rotating the rotating component 100a, at least the drive shaft portion 9a may cause elastic torsional deformation. For example, the influence of the elastic torsional deformation of the drive shaft portion 9 a may reach the rotating body 3. As a result, as in the measurement characteristics of the conventional rotation angle measuring device shown in FIG. 4, the encoder 4 has an apparent rotation angle θ1 due to the rotation of the rotating component 100a and the drive shaft portion 9a and the rotating body 3 itself due to elastic torsional deformation. There is a possibility that the rotation angle obtained by adding up the so-called torsional rotation angle Δθ1 rotating in the upper rotation direction is measured. This torsional rotation angle Δθ1 may cause an error and cause a decrease in measurement accuracy.
[0024]
On the other hand, in this embodiment, as shown in FIG. 1, the resistance addition part 5 which adds resistance to rotation of the rotary body 3 is provided. As a result, a predetermined force is applied to the rotating body 3 so that a predetermined counter torque Tr that opposes the rotational torque T is generated against the rotational force that rotates the drive shaft 9a against the frictional resistance Rf, that is, the rotational torque T. It is possible to apply the resistance force Rr (see FIG. 3A). As a result, as shown in FIG. 3A, the rotational angle error Δθ2 can be reduced to at least a small rotational angle error Δθ1 (see FIG. 4) in the prior art that does not have the resistance adding portion 5. (Δθ2 <Δθ1).
[0025]
In addition, as a rotation angle measuring device which has this effect, the structure of the comparative example shown in FIG. 2 may be sufficient. As shown in FIG. 2, the resistance adding portion 51 includes urging means 51 a such as a compression spring. This resistance adding portion 51 can generate a frictional force for resistance against the frictional resistance Rf, that is, a resistance force Rr, with the rotating body 3 using the axial force generated by the compression spring 51a. Note that the frictional force for resistance by the compression spring 51a is given a constant frictional force for each specification of the compression spring 51a. Therefore, the magnitude of the frictional resistance Rf generated using the compression spring 51a of one specification is used. Accordingly, it is difficult to change the frictional force for resistance, that is, the resistance force Rr to a predetermined drag force.
[0026]
On the other hand, in this embodiment, the rotating body 3 further includes a shaft portion 3a having a substantially small diameter body and a disk portion 3b having a substantially large diameter body having a larger diameter than that of the substantially small diameter body. And the resistance addition part 5 is set as the structure which can apply predetermined resistance Rr to rotation of the disk-shaped part 3b. As this configuration, as shown in FIG. 1, a so-called disc brake can be configured. Due to the size of the disc of the disc brake, that is, the large diameter of the substantially large-diameter body, a predetermined counter torque Tr that opposes the rotational force T with a smaller resistance than the predetermined resistance generated by the shaft portion 3a. Can be generated. Thereby, the resistance addition part 5 can adjust easily the load which hold | maintains the rotary body 3, ie, the disk shaped part 3b, ie, predetermined | prescribed resistance force Rr.
[0027]
In the rotator 3, as shown in FIG. 1, the portion of the rotator 3 that is connected to the drive device 9 side (specifically, the drive shaft portion 9a) side and to which the resistance force Rr is applied by the resistance adding portion 5 is provided. Hereinafter, the part 31 of the rotating body is referred to, and the other part of the rotating body 3 on the rotation angle measuring unit 4 side is hereinafter referred to as the other part 32 of the rotating body. As shown to Fig.3 (a), it can suppress that the influence of elastic torsion deformation is exerted on the other part 32 of a rotary body at least by adding the resistance force Rr by the resistance addition part 5. FIG. As shown in FIG. 3B described later, the resistance force Rr applied to the disk-shaped portion 3b by the resistance adding portion 5 and the resistance torque Tr are substantially equal to the rotational torque T by the frictional resistance force Rf (Tr = T). By adjusting to a predetermined drag force Rr, it is possible to remove the influence of elastic torsional deformation caused by the frictional resistance force Rf.
[0028]
In FIG. 3, the inter-axis distance L <b> 9 a is a shaft length from the end on the rotating component 100 a side to the end on the rotating body 3 side in the drive shaft portion 9 a of the drive device 9. The inter-axis distance L3 is the length of the shaft portion from the end on the drive shaft portion 9a side to the end on the rotation angle measurement portion 4 side of the rotating body 3. Furthermore, the inter-axis distance L31 and the inter-axis distance L32 are shaft lengths corresponding to a part 31 of the rotating body and the other part 32 of the rotating body, respectively.
[0029]
Furthermore, in this embodiment, a control device 6 is provided as a control means for driving and controlling the resistance adding unit 5. The control device 6 uses a microcomputer or the like, and is a read only memory (ROM) in which programs necessary for various software processes are stored, a central processing unit (CPU) for executing the programs, and a program necessary for the programs. It is mainly composed of a writable memory (RAM) for temporarily storing variables. As shown in FIG. 1, the drive device 9 is configured by an electric motor, for example, and the control device 6 is configured to receive a current signal of the electric motor.
[0030]
As a result, the control device 6 applies the resistance force Rr applied to the rotating body 3 (specifically, the disk-shaped portion 3b) by the resistance adding portion 5 to the frictional resistance force Rf generated by the rotation of the driving device 9, that is, the rotation of the rotating component 100a. It is possible to adjust the resistance Rr against the resistance. Specifically, the control device 6 can derive the rotational force generated by the electric motor, that is, the rotational torque, from the current signal. This rotational torque is substantially equal to the rotational torque T that rotates the rotating component 100a in a state where there is a frictional resistance. Therefore, when the resistance adding unit 5 is driven and controlled by the control device 6, the resistance force Rr applied to the rotating body 3 (specifically, the disc-like portion 3b) by the resistance adding unit 5 is compensated for the rotational torque T. It is possible to adjust so as to be Tr. As a result, as shown in FIG. 3B, the resistance force Rr applied to the disk-like portion 3b by the resistance adding portion 5 is substantially equal to the rotational torque T by the frictional resistance force Rf (Tr = T). By adjusting to the predetermined drag force Rr, it is possible to remove the influence of elastic torsional deformation caused by the frictional resistance force Rf (rotation angle error Δθ2 = 0).
[0031]
In the rotation angle measuring device 1 of the present invention described above, it is possible to apply a predetermined resistance force Rr to the resistance adding portion 5 in accordance with the frictional resistance force Rf generated according to the rotation of the rotating component 100a. Regardless of the size of Rf, the rotation angle measuring unit 4 can measure the rotation angle of the drive device 9 that is the measurement object with high accuracy as the rotation angle of the rotation body 3.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a configuration of a rotation angle measuring device according to an embodiment of the present invention.
FIG. 2 is a configuration diagram showing a configuration of a rotation angle measuring device of a comparative example.
FIG. 3 is a graph showing a relationship among a rotation angle at a rotating component to be rotated, a rotation angle at a drive shaft portion of the measurement object, and a rotation angle at the rotation object in the rotation angle measurement device of the present embodiment. 3A shows a case where a predetermined resistance force is applied to the rotating body by the resistance adding unit. FIG. 3B shows a case where the predetermined resistance force is rotated by a drag that cancels out the frictional resistance force generated in the rotating component. It is a graph which shows the case where it adds to a body.
FIG. 4 is a graph showing a relationship between a rotation angle at a rotating component to be rotated, a rotation angle at a drive shaft portion of the measurement object, and a rotation angle at the rotation object in a conventional rotation angle measurement device;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Rotation angle measuring device 2 Installation base part 3 Rotating body (a part of to-be-measured body)
3a Shaft (substantially small diameter body)
3b Disc-shaped part (substantially large diameter body)
31 Part of Rotating Body 32 Other Part of Rotating Body 4 Encoder (Rotation Angle Measurement Unit)
5 Resistance addition part 6 Control apparatus (control means)
9 Drive device (measurement object)
9a Drive shaft 100 product (object to be rotated)
100a Rotating parts (objects to be rotated)
Rf Friction resistance force Rr (resistance addition unit 5 applies to rotating body 3) resistance force

Claims (1)

A driving device for generating a rotational driving force;
A drive shaft that protrudes rotatably from both ends of the drive device, is connected to a rotating component that is rotationally driven by the rotational driving force on one end side, and is provided with a rotating body on the other end side
A rotation angle measurement unit for measuring the rotation angle of the rotating body;
A resistance adding unit for applying a resistance force to the rotation of the rotating body;
Control means for driving and controlling the resistance adding unit;
Rotational torque deriving means for deriving rotational torque (T) due to frictional resistance (Rf) of the rotating component;
With
The control unit adjusts the resistance force (Rr) applied to the rotating body by the resistance adding unit so that the resistance torque (Tr) is equal to the rotational torque (T) derived by the rotational torque deriving unit. A rotation angle measuring device characterized by that.

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