JPS6013449A - Servo motor - Google Patents

Abstract

PURPOSE:To measure the output torque of a motor without using a pressure sensor or the like by providing slits at both ends of a rotational shaft of a rotor, forming encoders, and detecting the phase difference between the output pulses of encoders. CONSTITUTION:Slits 51, 52 which have equal size and interval are provided at both ends of a rotational shaft 3 of a rotor 1. Projectors 11, 12 and photoreceptors 21, 22 are respectively disposed in response to the slits 51, 52. Lights emitted from the projectors 11, 12 are respectively reflected on the slits 51, 52, and received by the photoreceptors 51, 52. Photoreception signals of the photoreceptors 21, 22 are converted into electric signals. The rotating speed of a servo motor is controlled by the electric signals.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a servo motor that is used in the fields of measurement and control and requires load feedback.

[Background technology]

A rotary encoder is one that detects the rotational position of a rotating body using a scale (marker) fixed to the detection shaft and a means for reading the scale.The reading means can be optical, magnetic, contact, etc. There is.

As a control method for a servo motor, speed control using a tacho generator or the like, position control using a rotary encoder, etc. are performed.

In recent years, with the development of assembly robots, it has become necessary not only to simply control speed during position but also to control force.

Conventionally, a pressure sensor or the like is attached to an actuator component attached to a motor to measure pressure and control force. .

[Purpose of the invention]

An object of the present invention is to provide a servo motor that can measure the output torque of the motor without using a pressure sensor or the like.

[Disclosure of the invention]

The gist of the servo motor according to the present invention is that slits are provided at both ends of the rotating shaft of the rotor to form an encoder that generates synchronized pulses, and the load torque is determined by the phase difference between the output pulses of each encoder when a load is applied. It is a patented BoMotor that detects.

The present invention will be explained below based on an embodiment shown in FIGS. 1 to 6.

This servo motor is mainly a coreless motor,
(1) is a cup-shaped rotor, and (2) is a magnet arranged inside the rotor. (3) is the rotating shaft of the rotor (1), and (4) is a commutator attached to the rotating shaft (3), which is powered by the brush (5).

Equally sized and equally spaced slits (
51) and (52) are provided at equal positions on the circumference.

Emitters (11), (12) and receivers (21), (22)
) are arranged corresponding to each of the slits (51, ) and (52). The light emitted by the projectors (11) and (12) is reflected by the sleeves (51) and (52) and is received by the receivers (21) and (22). Photoreceiver (21), (
The light reception signal generated in 22) is returned to an electrical signal. This electrical signal controls the rotation speed of the servo motor. That is, each pair of floodlights (11) or (1
2) and the light receiver (21) or (22) and (6) and the sleeve) (51) or (52) work as reflective optical encoders.

However, if the slit (51) side of the rotating shaft (3) is used as the input side and the slit (52) side is used as the output side, the output from each encoder will be as shown in Figure 2 when there is no load (generating synchronous pulses). In the country, (a+ is input side Noharus, (
In b), where the pulse on the output side is shown, power is input to the input side, and when a load is applied to the output side, twisting occurs in the rotating shaft (3). Therefore, the output from each encoder produces a phase difference ψ proportional to the torsion angle of the rotating shaft (3).

When a load torque of 1' is applied to the motor, a torsion angle θ occurs on the shaft.

T=GI'--... (1) P'1 (distance between measurement points of (51) and (52)) As a result, (41) phase difference ψ occurs between the outputs of each encoder. If the number of slits provided in the circumferential direction of the gold is n, then the following relationship exists.

θ = ÷ (2) Therefore, by measuring the phase difference ψ from (1) and (2), the load torque,
That is, it becomes possible to measure the generated torque T.

Also, on one side of each encoder, there is a slit and a 90°
By providing phase-shifted slits, slits indicating the origin, and corresponding light receivers, the rotational position, rotational direction, and origin of the rotating shaft (3) can also be detected.

The slits can be formed by cutting gears on the rotating shaft (3) like a gear, or by discoloring the slits to black at equal intervals to create non-reflective areas.

〔Effect of the invention〕

As described above, according to the servo motor according to the present invention, not only the displacement speed but also the torque (5) on the rotating shaft can be detected, so that control using feedback of the load is possible.

[Brief explanation of the drawing]

1 to s3 are diagrams showing one embodiment of the present invention, in which FIG. 1 is a sectional view, and FIGS. 2 and 6 are graphs. Patent applicant Matsushita Electric Works Co., Ltd. Patent attorney Toshimaru Takemoto (and 2 others) (6) Figure 2 Figure 3 27c

Claims (1)

[Claims] (1) A servo motor characterized in that slits are provided at both ends of the rotating shaft of the rotor to form an encoder that generates synchronized pulses, and load torque is detected by the phase difference between the output pulses of each encoder when a load is applied. .