JP2002358001A - Pendulum device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain isochronism of a pendulum device. SOLUTION: A position detecting sensor 5 which detects a weight 1 that passes a center O and a solenoid 4 which pulls in the weight 1 are positioned at the center O of the oscillation of a pendulum. When the sensor 5 detects the weight 1, a position detecting timer starts counting time, the energizing position of the solenoid 4 is determined and energizing is started by the time-up of the timer. At the same time, an energizing timer starts counting time and the energizing of the solenoid 4 is stopped by the time-up of the timer. When the sensor 5 detects the weight 1 next time, a gate timer starts counting time and the rest of the timers are made inoperable until the time-up of the gate timer. Thus, no external force is exerted to the weight 1 along the direction other than its moving direction so as to maintain isochronism of the pendulum device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pendulum device which is installed or exhibited in museums, archives, art museums, event venues, and the like as education, entertainment, advertisement, and monuments.

[0002]

2. Description of the Related Art A pendulum device in which one end of a hanging thread is fixed and a weight is hung is installed as an educational experiment in a museum or a museum, and is displayed as a monument in a science museum or an event hall.

As such a pendulum device, there is a Foucault pendulum, for example. Foucault's pendulum is a pendulum used to investigate the effect of earth rotation on the vibration surface of a simple pendulum.The pendulum rotates in the opposite direction to the angular velocity ω component of the earth's rotation, that is, in the northern hemisphere, clockwise when viewed from above. In the southern hemisphere, it rotates counterclockwise.

However, in the conventional pendulum device, friction of a fulcrum for suspending the pendulum, air resistance, elongation and rotation of the suspended string, rotation due to twisting, the position of the center of gravity of the pendulum, the natural vibration of the building, the influence of air convection due to air conditioning, geomagnetism, etc. (For example, when iron is used for the weight), the pendulum vibrates not in a simple vibration but in an elliptical orbit. That is, the isochronism cannot be maintained.

In order to solve this problem, for example, a knife-edge type device is used to suspend the pendulum to reduce friction, or a piano wire is used as the suspending thread to reduce air resistance. .

A turntable is provided below the orbit of the pendulum, two solenoids are linearly arranged on the turntable, and the elliptical motion is corrected by attracting the pendulum by the magnetic force of the operated solenoid. At the same time, by rotating the turntable according to the rotation of the earth (the rotation speed of the pendulum is defined by latitude, the rotation speed of the turntable can be set by calculation), so that the pendulum takes a theoretical orbit It was showing like.

[0007]

However, in the apparatus using the knife-edge type apparatus described above, the parts are expensive and the installation cost is high, but the maintenance cost is also high due to the wear of the knife edge. Problem.

Further, in the case of using a piano wire, there is a problem that the hanging string is easily cut and the maintenance is troublesome.

[0009] On the other hand, in the case of using the turntable system, although it looks like a theoretical trajectory, there is a problem that it must be a device that cannot be described as an educational experiment.

An object of the present invention is to reduce the cost and maintain isochronism without using a piano wire which is easy to cut. In addition, it is an object of the present invention to make it possible to carry out an experiment with the principle as it is, without using a conventional simulated experimental device.

[0011]

In order to solve the above-mentioned problems, according to the present invention, a solenoid is provided at a center point of vibration of a simple pendulum in which one end of a hanging string is fixed and a weight formed of a magnetic material is suspended. That is, the solenoid at the center point is controlled based on the position of the weight detected by the position detection sensor.

By adopting such a configuration, the controller controls the solenoid based on the position of the weight detected by the position detecting sensor, and the friction of the fulcrum, the air resistance of the hanging thread, the rotation of the hanging thread due to the elongation or twist of the hanging thread. By compensating for the amount of attenuation due to the position of the center of gravity of the pendulum, the natural vibration of the building, air convection, etc., these can be canceled and a vibration state close to the theoretical value (isochronous) can be maintained.

At this time, no matter in which direction the pendulum vibrates (in the case of Foucault's pendulum, the vibrating surface rotates), the pendulum passes through the center of the vibration, and can be compensated for by the solenoid provided at the center of the vibration.

Further, the position detecting sensor detects a weight passing through the center of the vibration of the pendulum, and an exciting position detecting timer for starting time keeping is provided by a detection output from the sensor. It is possible to adopt a configuration in which the solenoid is excited by the time-up signal that is output.

By adopting such a configuration, the solenoid can be excited at an arbitrary position of the pendulum by changing the time-up time of the excitation position detection timer, so that the compensation amount for the pendulum can be changed.

At this time, a solenoid provided at the center of the vibration is disposed below the trajectory of the pendulum so that its pole is directed upward, and a time-out signal from the position detection timer is used to start time counting for the excitation. A timer is provided, and the excitation of the solenoid is canceled by a time-up signal output from the excitation timer at a point where the tangent of the track on which the pendulum descends toward the center of vibration coincides with the pole of the solenoid. can do.

By adopting such a configuration, when the pendulum descends toward the center of vibration, the solenoid is excited to exert a suction force, so that the vibration of the pendulum can be accelerated.

In addition, since the excitation of the solenoid is released at a point where the tangent of the trajectory of the pendulum coincides with the pole of the solenoid, the trajectory from this release point to the center of vibration has a shallow angle and is not in the vibration acceleration region. In this area, the solenoid does not exert a suction force so that natural vibration can be generated.

Further, by adopting a configuration in which the solenoid is excited only on one side of the amplitude of the pendulum, a free period in which the solenoid does not operate is provided so that the pendulum can behave in a natural state. it can.

At this time, after the excitation of the solenoid is released, when a detection output from the position detection sensor is output, a gate timer for starting time measurement is provided, and detection of the position detection sensor is performed by a time-up signal of the gate timer. A configuration in which output is received can be adopted.

By adopting such a configuration, it is possible to receive the detection output of the position detection sensor and not operate the position detection timer and the excitation timer until the gate timer expires. Can be prevented from energizing the solenoid on one side.

Further, by adopting a configuration in which the pole of the solenoid facing upward is an N pole, the orbit of the pendulum becomes an elliptical orbit due to the influence of geomagnetism.
If it is a pole (in the case of the Northern Hemisphere), it can be canceled.

At this time, it is possible to adopt a configuration in which the pendulum device is a Foucault pendulum.

[0024]

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

The pendulum device of this embodiment shown in FIG. 1 is for reproducing an experiment of Foucault's pendulum, and includes a pendulum M in which a weight 1 is fixed to a hanging base 3 of a ceiling with a pendulum hanging thread 2, and a pendulum M Solenoid 4 provided at the center O of vibration
And a position detection sensor 5 and a controller 6.

The weight 1 is made of iron (chrome-plated) and has a spherical shape with a weight (mass) of 35 kg.

The suspending thread 2 is a SUS304 wire having a diameter of 2 mm, one end of which is fixed to the suspending base 3 of the ceiling by wire caulking, and the weight 1 is attached to the other end and suspended. At this time, the distance 1 from the hanging point 3 of the ceiling, which determines the period of the pendulum, to the center of gravity of the weight 1 of the pendulum is 12550 mm.

The solenoid 4 is formed by winding a coil around an iron core having a diameter of 30 mm. For example, a pole (N here) is provided below the orbit ob of the pendulum, here under the floor.
The pole P is arranged with the P facing upward, and a magnetic flux density of about 300 Gauss is generated at the center of the pole P arranged upward.

As described above, the solenoid 4 has the center O of vibration.
, The pendulum M may vibrate in any direction of 360 °.

The position detecting sensor 5 is a sensor for detecting the weight 1 of the pendulum M, and is provided, for example, on the pole P of the solenoid 4 as shown in FIG. Therefore, it is necessary to use a sensor that is not affected by magnetism as the sensor 5, and a laser sensor or the like can be used in addition to the optical sensor. In this embodiment, the weight 1 passing directly above is detected by using a reflection-type optical sensor whose detection surface faces upward.

The controller 6, as shown in FIG.
It comprises an interval timer 7, a sequencer 8 and an output controller 9.

The interval timer 7 is composed of three timers, an excitation position setting timer 7a, an excitation timer 7b and a gate timer 7c. FIG. 3 shows a time chart of the timers 7a to 7c.

The excitation position setting timer 7a includes a pendulum M
When the detection signal of the weight 1 is input to the sequencer 8 from the position detection sensor 5,
The excitation position setting timer 7a starts counting time, and outputs a time-up signal to the sequencer 8 with the set counting time. By doing so, since the period of the pendulum M is always constant, it is possible to detect that the weight 1 is at a predetermined position from the time measurement.

The excitation timer 7b is used to set the excitation time of the solenoid 4. When the excitation position setting timer 7a outputs a time-up signal, the timer starts counting by the time-up signal. When the sequencer 8 excites the solenoid 4 on the basis of the above, vibration can be applied to the pendulum M as described later.

The gate timer 7c is a timer for operating the solenoid 4 only during one side of the amplitude of the pendulum M. When the detection signal of the weight 1 is output from the position detection sensor 5 to the sequencer 8, ), The gate timer 7c starts measuring time, and the operation of the excitation position setting timer 7a and the excitation timer 7b is prohibited until the time count is up (for example, the position detection sensor is output by the output of the gate timer 7c). 5 outputs may be gated). By doing so, the magnetic field of the solenoid 4 does not act on the rotation axis of the pendulum M, and the pendulum M can be rotated (clockwise in the northern hemisphere) in a state close to nature.

The sequencer 8 incorporates, for example, a microprocessor. As shown in FIG. 2, the sequencer 8 is connected to the position detection sensor 5, the interval timers 7a to 7c and the output controller 9, and outputs the position detection sensor 5 and the interval timer. The control of the solenoid 4 is performed based on the time-up signals 7a to 7c.

The output controller 9 comprises a drive circuit 9b for driving the solenoid 4, and a drive circuit 9a for driving indicator lamps (for solenoid and sensor) for monitoring.

This embodiment is configured as described above.
The operation of the pendulum device will be described with reference to the flowchart of FIG.

In this pendulum device, after the power is turned on (process 100, hereinafter "process" is omitted), when the pendulum M is slightly inclined and separated from the vertical line, the weight 1 starts to vibrate with a small amplitude (200). At this time, the amplitude given to the pendulum M is set to be larger than the detection area of the position detection sensor 5. Then, the weight 1 of the pendulum M to which the vibration is applied is detected when passing above the sensor 5 which has started to operate (300).

When the sensor 5 detects the weight 1, a detection signal thereof is input to the sequencer 8, and the sequencer 8 operates the excitation position detection timer 7 according to the input detection signal.
Activate a to start timing (400). At this time, the time is set to T1 seconds in advance,
As shown in FIG. 5, the excitation position of the solenoid 4 is
Is set to be a Y point which descends toward the center of vibration after reaching the top dead center of the amplitude. The reason why the excitation position can be accurately set by using the timer is that the period of the pendulum is constant.

Therefore, as shown in FIG. 3, when a time-up signal is output from the excitation position setting timer 7a, the sequencer 8 excites the solenoid 4 (50).
0) At the same time, the exciting timer 7b starts counting time.
Then, the solenoid 4 is excited until the excitation timer 7b reaches the time-up T2, so that the solenoid 4 is excited only in the section between the points Y and Z shown in FIG. In this way, the excited solenoid 4 attracts the weight 1 and accelerates the vibration of the pendulum M to compensate for the attenuation (600). At this time, if the excitation is performed in the section between the points Z and O in FIG. 5, the point Z is such that the trajectory ob of the weight 1 when the pendulum M is oscillated in a single oscillation is tangential to the pole P at the upper end of the solenoid 4 ( (A position in contact with the tangent line f), and on the point O side, the trajectory of the weight 1 becomes horizontal, and the force of the solenoid 4 sucking the weight 1 becomes larger than that of acceleration. In this case, the weight 1 is pulled downward, causing up and down vibration and hindering movement. Therefore, by exciting the solenoid 4 only in the section between the Y point and the Z point, the amount of attenuation can be compensated without hindering the movement of the pendulum M.

Here, the actual excitation timing (ON timing) of the solenoid 4 at the point Y is set to an ON timing from a magnetic field position of 3 gauss or less in a static state due to the magnetic field strength of the solenoid 4. . Further, the actual position of the Z point is calculated by obtaining the delay time τ of the hysteresis loss of the solenoid 4. That is, when the excitation time of the solenoid 4 is T2, the energization time is (T2-
τ) seconds.

The ON / OF of the solenoid 4 at each point
The switching of F is preferably controlled with an accuracy of about 1/100 second.

Then, when the exciting timer 7b times up at T2 seconds, the pendulum M moves freely, and the weight 1 moves from the point Z to the point O and passes through the position detecting sensor 5. Therefore, when a detection signal of the weight 1 from the sensor 5 is input to the sequencer 8 (700), the gate timer 7c is operated to start timekeeping in response to the input detection signal. At this time, this timer 7c
Is set to T3 seconds, and as shown in FIG. 3, the clocking time is set to the remaining half cycle of the vibration of the pendulum M. During this time, for example, the timer 7c is gated so that the excitation position setting timer 7a and the excitation timer 7b are not activated by the detection signal from the position detection sensor 5.

In this way, during this half cycle, the solenoid 4 is not excited, the magnetic field of the solenoid 4 does not act on the rotating shaft of the pendulum M, and becomes free, so that the pendulum M is close to natural. It rotates so that it can reproduce an experiment close to the theoretical value.

Thereafter, by repeating the processes 300 to 800, the amount of attenuation can be supplementarily supplemented, and the pendulum M can maintain isochronism. As a result, the pendulum M is rotated in accordance with the rotation of the earth, so that the experiment can be performed as it is without using a pseudo experimental device.

[0047]

According to the present invention, as described above, the principle can be used as it is without using a pseudo experimental device.

Therefore, there is no need to use a knife-edge type device for the fixed suspension of the ceiling. Also, in order to reduce the air resistance applied to the hanging string when the pendulum makes a simple vibration,
In the past, piano wires that were easy to cut had to be used, but there was no need to use piano wires that were easy to cut,
Since inexpensive twisted wires can be used, manufacturing costs can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment.

FIG. 2 is a block diagram of a controller according to the embodiment;

FIG. 3 is a time chart of the embodiment.

FIG. 4 is a flowchart of an embodiment.

FIG. 5 is an operation explanatory view of the embodiment.

[Explanation of symbols]

 Reference Signs List 1 weight 2 hanging thread 3 hanging source 4 solenoid 5 position detection sensor 6 controller 7 interval timer 7a excitation position setting timer 7b excitation timer 7c gate timer 8 sequencer 9 output controller f tangent l distance M pendulum O center of vibration P pole ob orbit

Claims (7)

[Claims] A solenoid is provided at a center point of the vibration of a single pendulum in which one end of a hanging string is fixed and a weight formed of a magnetic material is suspended, and the solenoid at the center point is detected by a position detection sensor. A pendulum device that controls based on position. 2. A position detection sensor for detecting a weight passing through the center of vibration of a pendulum, an excitation position detection timer for starting time measurement based on a detection output from the sensor, and an output from the timer. 2. The solenoid according to claim 1, wherein said solenoid is excited by a time-up signal.
6. The pendulum device according to claim 1. 3. A solenoid provided at the center of the vibration is disposed below the trajectory of the pendulum with its poles directed upward, and an excitation timer is provided for starting timing by a time-up signal of the position detection timer. 3. The method according to claim 1, wherein the excitation of the solenoid is released by a time-up signal output from the excitation timer at a point where a tangent of a trajectory where the pendulum descends toward the center of vibration coincides with a pole of the solenoid. The pendulum device as described. 4. The pendulum device according to claim 1, wherein the solenoid excites only the amplitude of one side of the pendulum. 5. A gate timer which starts counting when a detection output from the position detection sensor is output after the solenoid is de-energized, and a detection output of the position detection sensor is provided by a time-up signal of the gate timer. 5. The pendulum device according to claim 4, wherein the pendulum device is adapted to receive the following. 6. The pendulum device according to claim 3, wherein a pole of the upwardly directed solenoid is an N pole. 7. The pendulum device according to claim 1, wherein said pendulum device is a Foucault pendulum.