JPH046473A - Acceleration measuring apparatus - Google Patents

Abstract

PURPOSE:To realize highly accurate measurement in super low frequency region by detecting the motion of a magnetic scale unit in the form of a position signal, subjecting thus detected signal to conversion with no distorsion and driving a linear motor slider. CONSTITUTION:A magnetic scale 10 takes out the position and the moving direction, shown by an arrow 16, of a magnetic scale slide shaft 9 in the form of positional signals based on the variation of magnetic force. The positional signals are then subjected to conversion so that sinusoidal motion of the slide shaft 9 is simply amplified on a linear motor slider 14. Consequently, linear reciprocal motion characteristics of the slider 14 along a guide shaft 15 are converted into sinusoidal motion characteristics along a profile formed on a cam 1, and thereby a sample acceleration sensor 16 fixed to the slider 14 performs a sinusoidal motion. Since the sensor 16 produces an output corresponding to the magnitude of acceleration, acceleration can be measured highly accurately in super low frequency region.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an acceleration measuring device that applies acceleration to an acceleration sensor and checks the performance of the acceleration sensor based on its output signal.

2. Description of the Related Art Conventionally, as shown in FIG. 2, this type of acceleration measuring device includes a rotary arm 33 that revolves around a center axis 31 in the direction of an arrow 32, and a rotary arm 33 that has a radius r from the center axis 31 of the rotary arm 33. The rotary table 35 is attached to an end and rotates in the direction of an arrow 34. An acceleration sensor 36 as a test object is mounted on the rotary table 35, and the acceleration is determined by the revolution speed of the rotary arm 33, the applied frequency is determined by the rotation of the rotary table 35, and the magnitude of acceleration at a certain applied frequency is determined by the rotation of the rotary table 35. It is designed to measure. If the acceleration at this time is α, the applied frequency f, and the radius r, then there is a relationship of α−r (2πf)2.

Further, as another device for measuring acceleration, there is a single pendulum type device that utilizes gravitational acceleration g as shown in FIG. This device includes a lever 42 having a length 1 and serving as a hanging simple pendulum whose base end is swingably fixed to a top plate 41, and a holder 43 fixed to the tip thereof.

An acceleration sensor 44, which is a specimen, is placed in the holder 43, and the acceleration generated by swinging it alternately in the directions of arrows 45 and 46 is measured. At this time, the gravitational acceleration g is the louver length! , the relationship with the applied frequency (also called period) T is as follows: T = 2πf
, the relationship between gravitational acceleration g, louver length 11 and head S is α=
-(g/j becomes S.

Furthermore, as another device for measuring acceleration, there is a method of electrically generating acceleration of sinusoidal motion using a sine wave generator as shown in FIG. In this device, a sine wave generated by a sine wave generator 21 is amplified by a power amplifier 22, and then applied to an electromagnetic exciter 23 using a linear motor to cause a slider 24 to reciprocate with sinusoidal motion characteristics. This applies acceleration to the trial acceleration sensor 25. 26 is an acceleration pickup for a feed bank attached to the electromagnetic exciter 23, and the signal detected here is fed back to the sine wave generator 21 and sent to the slider 24.
is configured to always perform sinusoidal motion.

Problems to be Solved by the Invention However, the conventional acceleration measuring device described above has the following problems.

First, in the device shown in Fig. 2, since the speed of rotation and revolution can be varied independently, it has the advantage of being able to vary the acceleration α independently for one applied frequency f. Since there are two types, mechanical vibration noise is likely to be generated, and since there are electric finger contacts, electrical noise is likely to be generated. Furthermore, the device tends to be large and expensive.

Next, in the device shown in FIG. 3, in order to make the acceleration sensor 44, which is the specimen under test, swing at a low frequency, or to increase the applied frequency T, the lever T is determined from the above equation. The length l must be increased, which increases the size of the device. Also, depending on how the lever 42 is released, the acceleration α
is likely to vary, and it is difficult to keep the attitude of the acceleration sensor 44, which is the test object, constant at all times.

Furthermore, although the device shown in Fig. 4 can give a relatively accurate sinusoidal motion to the slider in the frequency range of 0.5Hz or higher, it is difficult to generate a sine wave in the frequency range of 0.51 (Z or lower). When the sine wave signal is amplified and converted from the vibrator 21 to the electromagnetic exciter 23, distortion occurs in the converted signal, making it difficult to give the slider accurate sine wave motion.Furthermore, since the torque applied to the motor fluctuates depending on the drive load, It is difficult to modify and give the slider accurate sine motion.

Furthermore, in any of the above acceleration measurement devices,
Measurement in the ultra-low frequency range from I Hz to DC level is extremely difficult.

The present invention solves the above-mentioned conventional problems, and provides an inexpensive and compact acceleration measuring device that can measure acceleration with high accuracy in the ultra-low frequency range of 1 fiz or less and at low accelerations. The purpose is to provide the following.

Means for Solving the Problems In order to achieve the above object, the present invention provides a measuring device that generates a sinusoidal motion using a small cam, a link mechanism, a Magnescale unit, and a slider. (It is designed to measure acceleration in the extremely low frequency and low acceleration region below z with high precision.

Operation The present invention has the following effects due to the above-described configuration. By using a small cam, a link mechanism, a Magnescale unit, and a slider, we create extremely accurate sinusoidal motion in the Magnescale, detect this motion as a position signal, and convert this signal to drive a linear motor. By sending the signal to the slider, the signal is transmitted to the slider without distortion even in the low frequency range, and accurate sinusoidal motion characteristics can be achieved even in the ultra-low frequency range below IHz, resulting in high precision. This has the effect of being able to measure acceleration.

Embodiment FIG. 1 is a diagram showing the configuration of an embodiment of the present invention. 1st
In the figure, A is a mechanical unit. In mechanical unit A, 1 is a cam, and a DC motor (
It is fixed by a key 3 to an output shaft 2 that transmits rotational power of a motor (not shown) via a reducer (not shown). Reference numeral 4 designates a link that swings about a fulcrum 5 through the cam follower 6 at one end by the operation of the cam 1, and a cam follower 7 is attached to the other end. The cam follower 7 slides inside a groove 20 formed in the guide block 8 due to the rocking movement of the link 4. Reference numeral 9 denotes a Magnescale slide shaft having a structure in which N poles and S poles are alternately and consecutively arranged in the horizontal direction in FIG. 1, and is fixed to the guide block 8. 10 indicates the position and movement direction of the Magnescale slide shaft 9 in the direction of the arrow 16 in FIG.
This is a magnet scale that extracts a position signal based on changes in magnetic force, and sends this position signal to the interface 11 via signal lines 12 and 13. The Magnescale slide shaft 9 and the Magnescale 10 constitute a Magnescale unit. The configuration of this mechanical unit A may be extremely small compared to the stroke required by the linear motor slider 14, which will be described later. 11 is an interface for driving the linear motor, and the position signal from the magnet scale 10 is transferred to the linear motor slider 1.
4 into a driving signal. ] 4 is a linear motor slider, which is attached to the test acceleration sensor 16 in the direction in which acceleration is applied in the horizontal direction in FIG. conduct. Further, the cam contour curve on the outer peripheral surface of the cam 1 is appropriately created after analyzing and considering the motion of the link 4 so as to realize a sinusoidal motion characteristic with respect to the Magnescale slide shaft 9.

Next, the operation of the above embodiment will be explained. In response to an input command from a DC motor controller (not shown), the DC motor (not shown) rotates, and the cam 1 also rotates via a reduction gear (not shown). Here, the link 4 swings in the directions of arrows a and b, using the fulcrum 5 as a fulcrum, following the contour curve of the cam 1. As a result, the Magnescale slide shaft 9 makes a reciprocating linear movement in the direction of the arrow 16 via the cam follower 7 and the guide block 8. The reciprocating linear motion characteristic of the Magnescale slide shaft 9 becomes a sinusoidal motion characteristic according to the contour curve of the cam 1, and the motion of the Magnescale slide shaft 9 is detected as a position signal by the Magnescale 10, and is transmitted to the interface 11 via the signal line 12.13. will be sent to.

Here, the above position signal is input to the Magnescale slide shaft 9.
The sinusoidal motion of the linear motor slider is simply expanded and sent to the linear motor slider 14. That is, compared to the size of the mechanical unit A, the stroke of the linear motor slider 14 can be made larger depending on the location and situation of use. Therefore, the reciprocating linear motion characteristic of the linear motor slider 14 along the guide shaft 15 becomes a sinusoidal motion characteristic according to the contour curve formed on the cam 1, and the test acceleration sensor 16 attached to the linear motor slider 14 exhibits this sinusoidal motion. This will result in the Since the acceleration sensor 16 under test outputs an output according to the magnitude of acceleration generated by this movement, the output value of the acceleration sensor 16 under test corresponding to the applied acceleration is output by an output device such as an onroscope or a pen recorder. will be measured. The applied frequency is determined by changing the rotation speed of the DC motor.

Furthermore, among sinusoidal curves, the maximum acceleration of a cycloid curve is approximately 13 times that of a single sinusoidal curve, so in order to give the same acceleration to the acceleration sensor 16 under test, a smaller stroke is required than in the case of a single sinusoidal curve. It turns out.

In this way, according to the above embodiment, the acceleration sensor under test 1
6 is held by the linear motor slider 14 with less vibration, it is possible to realize smooth movement with less vibration, and it also blocks vibrations from rotating parts such as the DC motor from being transmitted to the acceleration sensor 16 under test. Furthermore, since the frictional resistance during reciprocating motion can be reduced as much as possible, sinusoidal motion characteristics can be more faithfully applied to the acceleration sensor 16 under test, and the ultra-low frequency region below IHz, O, IG It has the effect that even acceleration in the low G range below can be measured with high precision.

Furthermore, mechanical unit A is linear motor slider 1
It can be made smaller compared to the required stroke of 4, and it can be installed at a position away from the linear motor slider via the signal wires 12 and 13, so it can be compact and versatile depending on the installation location. It also has the effect of allowing different installation methods.

Although a linear motor slider is used in this embodiment, an air slider or the like may also be used instead. Further, the motion curve given to the acceleration sensor 16 under test, that is, the cam curve of the cam 1, can be variously changed depending on the type of acceleration sensor that is the test object or the type of measurement value required. Even in these cases, the same effects as in this embodiment can be obtained.

Effects of the Invention As is clear from the above embodiments, the present invention uses a cam, a link mechanism, a Magnescale unit, and a slider to detect the movement of the Magnescale unit as a position signal, and to detect this movement as a position signal. Since the signal is converted without distortion and the slider is driven, the motion characteristics created in the cam can be accurately reproduced on the acceleration sensor installed in the slider even in ultra-low frequency motion, and even in the ultra-low frequency region of 0.5 Hz or less. Since the acceleration measurement can be achieved with extremely high precision, and the mechanism that generates the sinusoidal motion can be miniaturized, the only space required for installation is the size of the slider, which has the effect of increasing the degree of freedom in installation methods.

[Brief explanation of the drawing]

Figure 1 is a schematic configuration diagram of an embodiment of the present invention, Figures 2 and 3.
4 are schematic configuration diagrams of conventional acceleration measuring devices, respectively. 1...Cam, 2...Output shaft, 3...
... Key 4 ... Link, 5 ... Fulcrum, 6.7 ... Cam follower, 8 ... Guide block, 9 ... Magnescale Slide axis, 10... Magnescale, 11...
・Interface, 12.13...Communication 11.
14...Linear motor slider, 15...
... Guide shaft, 16 ... Acceleration sensor under test,
20...Groove. Name of agent: Patent attorney Shigetaka Awano and 1 other person

Claims (1)

[Claims] A cam having a cam curve for obtaining predetermined motion characteristics, a motor that rotationally drives the cam, a link mechanism that is driven by the cam to perform rocking motion, and a reciprocating motion that is driven by the link mechanism. An acceleration measuring device comprising a Magnescale unit, an interface that converts an output signal from the Magnescale unit, and a slider that performs reciprocating linear motion based on the output signal from the interface and holds a specimen.