JP2011232121A - Visual force display, visual force science teaching material and science toy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a force display device capable of visually displaying a direction of acting force and magnitude thereof without restriction of the direction when in use.SOLUTION: Based upon accelerations in a X-axis direction, a y-axis direction and a z-axis direction to be obtained from a triaxial acceleration sensor 20, as to each of axis directions, short cycle acceleration values (Sx, Sy and Sz) responding to force other than gravity acting on the triaxial acceleration sensor 20 and long cycle acceleration values Lx, Ly and Lz responding to the gravity acting on the triaxial acceleration sensor 20 are calculated. Then, based upon the short cycle acceleration values (Sx, Sy and Sz) and the long cycle acceleration values Lx, Ly and Lz, display information for each of axis directions is created. Based upon this display information, the direction of the force acting on the axis direction and the magnitude thereof are displayed.

Description

  The present invention relates to a display that can visually recognize the direction and magnitude of a force acting on an object.

In the field of school education, crying away from science. One reason for this is that some of the things handled in science are not visually recognizable. One example is the concept of power. In other words, because the force is invisible, it cannot visually grasp its direction and size, making it one of the difficult things for junior and senior high school students. Therefore, there is a need for teaching materials that can visualize the direction and magnitude of the force acting on an object in an educational setting.
Various tilt sensors have been proposed in which two-axis (or three-axis) accelerations orthogonal to each other are detected by an acceleration sensor to obtain an angle formed by a reference direction and gravitational acceleration, that is, a tilt angle (Patent Documents 1 and 2). . Finding the angle of inclination using an acceleration sensor gives suggestions for recognizing the direction of force, but Patent Literature 1, Patent Literature 2, etc. visualize both the direction and magnitude of force. The device that can be displayed is not disclosed.
In contrast, the present inventors have proposed a device capable of visualizing and displaying both the direction and magnitude of force in Non-Patent Document 1.

Japanese Patent No. 3114571 JP 2008-96355 A

Ito Akihiko / Watanabe Kazuhiro, Production of Power Indicator “Fi-Cube” to Support Learning of Power and Class Practice, Bulletin of Faculty of Education, Utsunomiya University, 59-2, 13-26, 2009

The force indicator (hereinafter referred to as a conventional force indicator) described in Non-Patent Document 1 is an original teaching material that can visualize the direction and magnitude of a force acting on an object. However, in the conventional force indicator, the acceleration output acquired in the z-axis direction of the three-axis acceleration sensor is used for displaying gravity and for calculating the inclination of the force indicator. Therefore, the conventional force indicator is set so as not to react to a short-time movement corresponding to the applied force, although gravity can be measured in the z-axis direction. On the other hand, the x-axis direction (or the y-axis direction) is set to react only to a short-time movement corresponding to the force, contrary to the z-axis direction. Therefore, the conventional force indicator cannot display force (acceleration) in the z-axis direction even when the z-axis direction is aligned in the vertical direction and is free-falling (or throwing up), so There is a restriction that the x-axis direction (or y-axis direction) is aligned in the vertical direction.
An object of the present invention is to provide a force indicator that can visually display the direction and magnitude of an acting force without being restricted in the direction of use.

The force is defined by the equation of motion F = m · a. That is, the force F acting on an object is represented by the acceleration a with the mass m as a proportional constant. Therefore, visualizing the acceleration of the object is equivalent to visualizing the force. The visual force indicator of the present invention (hereinafter simply referred to as force indicator) follows this idea, and the acceleration of an object is measured by a three-axis acceleration sensor provided therein, and the force is visually detected based on this. Display.
Describes the requirements to have as a force indicator. An object placed on a horizontal support surface is subject to two forces: the earth's gravity and the vertical drag received from the support surface. Therefore, in this case, it is necessary to perform the same amount of display downward and upward in the z-axis direction (vertical direction). However, since gravity always acts on an object on the earth, the stationary acceleration sensor always outputs upward acceleration, that is, upward force. This upward force corresponds to the normal force received from the support surface. However, an acceleration output corresponding to gravity cannot be obtained.

The conventional force indicator described above for this problem uses the output of acceleration acquired in the z-axis direction to display gravity, but also uses it to calculate the inclination of the force indicator. Therefore, in the case of free fall (or throwing up), there is a restriction that the x-axis direction is aligned with the vertical direction. On the other hand, the present invention provides both information relating to acceleration corresponding to gravity and information relating to acceleration corresponding to forces other than gravity for each axis (x axis, y axis and z axis) of the triaxial acceleration sensor. Therefore, it is possible to eliminate restrictions on the direction of use.
The force indicator of the present invention includes a three-axis acceleration sensor, a controller, and a display body.
The triaxial acceleration sensor detects acceleration in each of the x-axis direction, the y-axis direction, and the z-axis direction that are orthogonal to each other.
Based on the acceleration in the x-axis direction, the y-axis direction, and the z-axis direction acquired from the triaxial acceleration sensor, the controller performs acceleration information S corresponding to a force other than gravity acting on the triaxial acceleration sensor for each axial direction. (Sx, Sy and Sz) and acceleration information L (Lx, Ly and Lz) corresponding to gravity acting on the triaxial acceleration sensor are calculated. The controller also generates display information for each of the axial directions based on the calculated acceleration information S (Sx, Sy, and Sz) and acceleration information L (Lx, Ly, and Lz).
The display body displays the direction and magnitude of the force acting in the axial direction based on the display information generated by the controller.

In the force indicator of the present invention, the controller can determine whether the force indicator is in an acceleration motion state or a non-acceleration motion state. By making this determination, it is possible to realize an appropriate display corresponding to acceleration motion or non-acceleration motion. This determination is made by comparing the reference gravity G0 specified after activation with the absolute value G1 of acceleration. However, the absolute value G1 of acceleration is given by G1 = (Sx ² + Sy ² + Sz ² ) ^1/2 from acceleration information S (Sx, Sy and Sz) calculated after specifying the reference gravity G0.

  Further, in the force indicator of the present invention, when the controller determines that the indicator is in a non-acceleration motion state, the acceleration value G (the direction is the same as the acceleration information L (Lx, Ly, and Lz) but is equal in magnitude. Gx = −Lx, Gy = −Ly, and Gz = −Lz) can be handled as display information corresponding to gravity acting on the triaxial acceleration sensor. If it is determined that the visual force indicator is in the state of acceleration motion, the acceleration value G (Gx) having the opposite direction and the same magnitude as the acceleration information L (Lx, Ly and Lz) before the acceleration motion is started. = −Lx, Gy = −Ly and Gz = −Lz) can be handled as display information corresponding to gravity acting on the triaxial acceleration sensor.

In the force indicator of the present invention, the controller can have a first mode and a second mode for displaying the direction and magnitude of the force.
In the first mode, when the directions of gravity G (Gx = −Lx, Gy = −Ly and Gz = −Lz) and acceleration information S (Sx, Sy and Sz) are opposite, gravity G and acceleration information S Are treated as independent display information. In the first mode, when the direction of gravity G (Gx = −Lx, Gy = −Ly and Gz = −Lz) and acceleration information S (Sx, Sy and Sz) are the same, gravity G and acceleration Information added with information S is handled as display information.
The second mode always includes gravity G and acceleration information S regardless of the direction of gravity G (Gx = −Lx, Gy = −Ly and Gz = −Lz) and acceleration information S (Sx, Sy and Sz). Is added as display information.

  In the force indicator of the present invention, the controller calculates acceleration information L (Lx, Ly and Lz) before specifying the reference gravity G0, and the acceleration information in each axial direction given when the reference gravity G0 is specified. L0 (Lx0, Ly0 and Lz0) can be stored as initial gravity values Gx0 = −Lx0, Gy = −Ly and Gz = −Lz).

  The visual force indicator according to the present invention is used as a science teaching material and a scientific toy.

  According to the present invention, for each axis (x-axis, y-axis, and z-axis) of the three-axis acceleration sensor, both information related to acceleration corresponding to gravity and information related to acceleration corresponding to force other than gravity are obtained. This made it possible to eliminate restrictions on the direction of use.

It is a perspective view which shows the external appearance of the force indicator in this Embodiment. It is a block diagram which shows the structure of the force indicator in this Embodiment. It is a flowchart which shows the procedure of the process in the controller in the force indicator of this Embodiment. It is a flowchart which shows the procedure of the process in the controller in the force indicator of this Embodiment, and shows the process after the process shown in FIG. An example of the table which defines the number of LED lighted according to the z-axis direction component of gravity is shown. The lighting state of the LED of the normal mode force indicator stationary on the horizontal plane is shown, (a) shows the xz display surface, and (b) shows the xy display surface. FIG. 6 shows the lighting state of the force indicator whose direction is changed from FIG. 6, (a) shows the xz display surface, and (b) shows the xy display surface. The lighting state of the LED of the force indicator in the normal mode that falls freely is shown, (a) shows the xz display surface, and (b) shows the xy display surface. The lighting state of the LED of the normal mode force indicator that undergoes linear acceleration motion on a horizontal plane in response to an external force is shown, (a) shows the xz display surface, and (b) shows the xy display surface. The lighting state of the LED of the normal mode force indicator that moves linearly at a constant speed on a horizontal plane without receiving external force is shown, (a) shows the xz display surface, and (b) shows the xy display surface. . The lighting state of the LED of the normal mode force indicator stationary on the inclined surface is shown, (a) shows the xz display surface, and (b) shows the xy display surface. The lighting state of the LED of the normal mode force indicator that freely slides on the inclined surface is shown, (a) shows the xz display surface, and (b) shows the xy display surface. (A) shows a force indicator in a normal mode placed on a disk that freely rotates around an axis S, and (b) shows a lighting state of LEDs on the xy display surface. It is a figure which shows the transition of the lighting state of LED of the xz display surface in the process in which the force indicator of the normal mode (1st mode) erected 90 degree | times clockwise. It is a figure which shows the transition of the lighting state of LED of a xz display surface in the process of freely dropping the force indicator of the actual action mode (2nd mode) supported by the horizontal surface. It is a figure which shows the transition of the lighting state of LED of the xz display surface when the force indicator of the normal mode (1st mode) stationary horizontally is artificially vibrated up and down.

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.
FIG. 1 is a perspective view showing an appearance of a force indicator 10 in the present embodiment, and FIG. 2 is a functional block diagram of the force indicator 10.
The force indicator 10 includes a three-axis acceleration sensor 20 (hereinafter simply referred to as an acceleration sensor 20), a controller 40 that receives acceleration information including electric signals output from the acceleration sensor 20, and processes the generated information to generate display information. And a display unit 60 in which a light emitting diode LED (hereinafter simply referred to as LED) is turned on based on the display information generated in step (b). In the following description, the direction of FIG.

<Case 11>
The force indicator 10 includes a rectangular parallelepiped case 11 having two adjacent surfaces as an xz display surface 12 and an xy display surface 13. The case 11 is configured by assembling a transparent acrylic resin plate, for example, but is not limited thereto. The case 11 is provided with a switch for starting (turning on) / stopping (turning off) the force indicator 10, but the description thereof is omitted here.

<Display unit 60>
An xz display substrate 14 is provided inside the xz display surface 12 of the case 11, and an xy display substrate 15 is provided inside the xy display surface 13. On the xz display board 14 and the xy display board 15, a plurality of display lamps each composed of LEDs are arranged in a cross shape to form an xz display body 16 and an xy display body 17. The display unit 60 is configured by the two display bodies 16 and 17. The x-axis, y-axis, and z-axis are as indicated by arrows in FIG. The necessary number of LEDs constituting the xz display body 16 and the xy display body 17 are turned on based on display information generated by the controller 40, and the direction and magnitude of the acting force are displayed.
The xz display body 16 forms a cross by arranging 10 LEDs in the x direction and 10 LEDs in the z direction on a straight line. The xy display body 17 also forms a cross by arranging 10 LEDs in the x direction and 10 LEDs in the y direction on a straight line. In the xz display body 16 and the xy display body 17, positive (+) and negative (−) are determined as shown in the figure centering on the intersection (origin) of the cross. For example, in the xz display 16, when an LED corresponding to the negative z-axis is lit, this indicates that the force indicator 10 is receiving gravity. The force indicator 10 indicates that 0.25 g (g: gravitational acceleration) is acting when one LED is lit. For example, as shown in FIG. 5, a table in which the acceleration Az in the z-axis direction is associated with the number of LEDs to be lit is provided, and the number of LEDs to be lit can be determined by referring to this table. it can.

<Acceleration sensor 20>
The force indicator 10 includes an acceleration sensor 20 in the case 11. The acceleration sensor 20 includes an x-axis sensor unit that detects an acceleration component in the x-axis direction, a y-axis sensor unit that detects an acceleration component in the y-axis direction, and a z-axis sensor unit that detects an acceleration component in the z-axis direction. The axis sensor unit, the y-axis sensor unit, and the z-axis sensor unit are arranged in the case 11 along the x-axis, y-axis, and z-axis of the force indicator 10 shown in FIG.
When the force indicator 10 performs an acceleration motion, the acceleration sensor 20 receives an inertial force in a direction opposite to the acceleration motion, and outputs acceleration as an electrical signal in each of the x-axis, y-axis, and z-axis directions. This electric signal (acceleration value) is Ax, Ay, and Az. As described above, the direction and magnitude of the force can be recognized by displaying the acceleration from the equation of motion F = m × a. Further, depending on the detection principle of the acceleration sensor 20, a piezoresistive type that utilizes a change in electrical resistance caused by a distortion of the crystal of the piezo element, a capacitance type that utilizes a change in capacitance, and a distortion caused by crystal distortion of the piezoelectric element. Although there are several types such as a piezoelectric type using voltage, any type of acceleration sensor can be used in the present invention.
In the present embodiment, it is assumed that the acceleration sensor 20 performs digital output, but a triaxial acceleration sensor that performs analog output may be used. In this case, it is necessary to add an element such as a filter amplifier circuit having a low-pass filter interposed between the acceleration sensor 20 and the controller 40. However, since this is known per se, it will be described here. Is omitted.

<Controller 40>
The force indicator 10 includes a controller 40 in the case 11.
The controller 40 processes the acceleration values of the x-axis, y-axis, and z-axis sent from the acceleration sensor 20 as follows in response to the switch being turned on. The controller 40 can be configured by, for example, a PIC (Peripheral Interface Controller). The PIC is a one-chip microcomputer in which an arithmetic processing unit, a memory, an input / output unit, and the like are incorporated in one IC, and is controlled by software stored in the memory.

[Initialization-sampling of acceleration values Ax, Ay and Az]
The controller 40 performs an initialization process after the force indicator 10 is activated. Here, it is assumed that the force indicator 10 is upright.
In order to perform initialization, the controller 40 continuously acquires (samples) acceleration values Ax, Ay, and Az from the acceleration sensor 20 and stores them in a memory. For example, by performing sampling at a cycle of 40 Hz (= 40 times / sec.), It is possible to follow the time change of the acceleration for 0.025 seconds. However, the sampling period of 40 Hz is merely an example, and it goes without saying that other sampling frequencies can be adopted. Ax is the acceleration value of the acceleration sensor 20 in the x-axis direction, Ay is the acceleration value of the acceleration sensor 20 in the y-axis direction, and Az is the acceleration value of the acceleration sensor 20 in the z-axis direction.

  The controller 40 calculates short-cycle acceleration values (acceleration information S) Sx, Sy, and Sz from the acceleration values Ax, Ay, and Az. Further, the controller 40 calculates long-period acceleration values (acceleration information L) Lx, Ly, and Lz from the acceleration values Ax, Ay, and Az. The specific contents of the short cycle acceleration values Sx, Sy, and Sz and the long cycle acceleration values Lx, Ly, and Lz will be described later.

  When the controller 40 does not change any of the short-cycle acceleration values Sx, Sy, and Sz during a predetermined number of samplings and Sx and Sy are 0, the force indicator 10 sets the Z axis to be vertical. Judging that it is left stationary, the initialization is completed. If any of the short-cycle acceleration values Sx, Sy, and Sz changes during the predetermined number of samplings, the controller 40 tries the initialization again.

[Memory of reference gravity G0 (G0 = Lz0)]
The controller 40 stores in the memory the long-term acceleration value Lz0 in the z-axis direction at the time of initialization as the reference gravity G0 (G0 = Lz0) as the magnitude of gravity received by the acceleration sensor 20 (force indicator 10). To do. The reference gravity G0 is used later to determine whether or not the force indicator 10 is accelerating.
Since the force indicator 10 is held in the starting posture, the reference gravity G0 obtained here is 1 g (g: gravitational acceleration).

  At the same time as storing the reference gravity G0, the short-period acceleration values Sx0, Sy0 and Sz0 and the long-period acceleration values Lx0, Ly0 and Lz0 at that time are also stored in the memory as initialized values. Further, the long-period acceleration values Lx0, Ly0, and Lz0 are stored as the magnitude and direction of gravity. The gravity Gx0, Gy0, Gz0 of each axis is represented by Gx0 = −Lx0, Gy0 = −Ly0, and Gy0 = −Lz0. However, at the time of initialization, Gx0 = 0, Gy0 = 0, and Gz0 = G0 are always set.

[Calculation of short cycle acceleration values Sx, Sy and Sz]
The controller 40 calculates short-period acceleration values Sx, Sy, and Sz from the acceleration values Ax, Ay, and Az obtained every sampling interval Δt seconds. The short cycle acceleration values Sx, Sy and Sz are, for example, TS = 0.1 sec. Is given as an average value of acceleration values Ax, Ay, and Az sampled during (short period). In TS seconds, NS measurements represented by TS = NS × Δt are performed. Thus, Sx, Sy and Sz are specified by: In the following description, the acceleration values Ax, Ay, and Az may be collectively referred to as acceleration A, and the short-period acceleration value may be collectively referred to as short-period acceleration value S.
Sx = (Ax1 + Ax2 + Ax3 +... + AxNS) / NS
Sy = (Ay1 + Ay2 + Ay3 +... + AyNS) / NS
Sz = (Az1 + Az2 + Az3 +... + AzNS) / NS
Here, it is clear from the above formula that at least NS times of measurement of the acceleration value A are necessary to calculate each short cycle acceleration value S. The first short-period acceleration value S1 calculated in this way is calculated as follows.
S ₁ = (S ₁ + S ₂ + S ₃ ... S _NS ) / NS
However, if it is calculated once S1 is the next S2, can be calculated by the following using the following measurement values S _{NS + 1} and the measured value so far (A ₁ is excluded).
S ₂ = (A ₂ + A ₃ +... + A _NS + A _{NS + 1} ) / NS
That is, the short cycle acceleration value S is sequentially calculated by taking the moving average of the acceleration values A. The same applies to long-period acceleration values Lx, Ly, and Lz described later. Therefore, after the first NS times, the short cycle acceleration value S and the long cycle acceleration value L are calculated for each sampling.

The short cycle acceleration value (Sx, Sy, and Sz) is, for example, a short cycle TS of 0.1 sec. Assuming that the sampling frequency of the acceleration value A is 40 Hz (Δt = 0.025 sec.), The average value of the acceleration values A sampled four times. Therefore, by calculating the short cycle acceleration value, it is possible to detect a force (not including gravity) applied to the force indicator 10 (acceleration sensor 20) moving in a short cycle. In addition, by calculating the short-period acceleration values for all three axes of the x-axis, the y-axis, and the z-axis, the restriction on the direction in which the force indicator 10 is used can be eliminated.
Here, the short period TS is 0.1 sec. However, this is only an example. As a tendency, if the short period TS is short, noise such as sound and vibration may be picked up. Conversely, if the short period TS is long, the display on the xz display body 16 and the xy display body 17 (light emission). The lighting of the diode LE is delayed without following the movement of the force indicator 10. Therefore, the short period TS is 0.01 to 0.3 sec. It is preferable to select from the following range, 0.05 to 0.15 sec. It is more preferable to select from the range.

[Calculation of long-period acceleration values Lx, Ly, and Lz]
The controller 40 calculates long-period acceleration values Lx, Ly, and Lz from the acceleration values Ax, Ay, and Az obtained every sampling interval Δt seconds. The long-period acceleration values Lx, Ly, and Lz are, for example, TL = 1.0 sec. Is given as an average value of acceleration values Ax, Ay, and Az sampled during (long period). In TL seconds, NL measurements represented by TL = NL × Δt are performed. Therefore, Lx, Ly, and Lz are specified by the following.
Lx = (Ax1 + Ax2 + Ax3 +... + AxNL) / NL
Ly = (Ay1 + Ay2 + Ay3 +... + AyNL) / NL
Lz = (Az1 + Az2 + Az3 +... + AzNL) / NL

The long-period acceleration values (Lx, Ly, and Lz) are, for example, a long-period TL of 1.0 sec. Assuming that the sampling frequency of the acceleration value A is 40 Hz, the average value of the acceleration values A sampled 40 times. The reason for calculating the long-period acceleration value is to detect the gravity acting on the force indicator 10. That is, on the premise that gravity always acts on the force indicator 10 and does not change in a short time like the short period TS, it is based on the long period TL that is sufficiently longer than the short period TS. By calculating the long-period acceleration value, gravity (size, direction) acting on the force indicator 10 is detected. In addition, by calculating long-period acceleration values for all three axes, the x-axis, the y-axis, and the z-axis, it is possible to eliminate restrictions on the direction in which the force indicator 10 is used.
Here, the TL between long periods is 1.0 sec. However, this is only an example. As a tendency, if the TL between the long periods is too short, it may be impossible to distinguish the force corresponding to the short period, and conversely, if the TL between the long periods is long, the display is similar to the short period TS. It is late without following the movement. Therefore, the long period TL is 0.5 to 10 sec. It is preferable to select from the following range, 0.8 to 5.0 sec. It is preferable to select from this range.
Hereinafter, when long-period acceleration values are generically referred to, they may be referred to as long-period acceleration values L.

[Calculation of absolute value G of acceleration]
The controller 40 calculates the absolute value G1 of acceleration using the calculated short cycle acceleration values (Sx, Sy, and Sz). The absolute value G1 is obtained by G1 = (Sx ² + Sy ² + Sz ² ) ^1/2 .
The controller 40 compares the calculated absolute value G1 with the previously stored reference gravity G0. By this comparison, it can be determined whether or not the force indicator 10 is accelerating. That is, if the force indicator 10 is not accelerating, G1 remains G0 and matches (G1 = G0), and if the force indicator 10 is accelerating, G1 is different from G0 (G1 ≠ G0). ). Hereinafter, the case of G1 = G0 (non-acceleration motion) is referred to as Case-A, and G1 ≠ G0 (acceleration motion) is referred to as Case-B. Case-A corresponds to either stationary or constant speed motion.

In Case-A (non-acceleration motion), long-period acceleration values Lx, Ly, and Lz indicate directions opposite to gravity, and the controller 40 stores Gx = −Lx, Gy = −Ly, and Gy = −Lz. To remember.
Here, since gravity always acts on an object on the earth, the stationary acceleration sensor 20 always outputs upward acceleration, that is, upward force. In this case, the force obtained from the output of the acceleration sensor 20 corresponds to the normal force received from the support surface of the object. However, there is no downward output corresponding to gravity. Therefore, gravity can be displayed by interpreting Gx = −Lx, Gy = −Ly, and Gy = −Lz.
On the other hand, in the case of Case-B (acceleration motion), since the direction of gravity is not known, the controller 40 does not perform special processing. Therefore, the memory stores acceleration values (Ax, Ay and Az) up to the previous sampling, short cycle acceleration values (Sx, Sy and Sz), and long cycle acceleration values (Lx, Ly and Lz).
Note that Gx = −Lx, Gy = −Ly, and Gy = −Lz may be collectively referred to as gravity G.

[Identify display information]
<Normal mode and actual operation mode>
Based on the above results, the controller 40 identifies the content to light and display the LED of the display unit 60. This display content is divided into a normal mode (first mode) and an actual action mode (second mode).
In the normal mode, even if the object is stationary, it is displayed that gravity and normal force are acting in the opposite direction with the same magnitude. In other words, the normal mode treats gravity specially. This is to match the display of the force indicator 10 with the content of science learning that gravity and vertical drag are balanced. However, in the stationary state, the gravity and the normal drag are actually balanced, and no force is applied to the force indicator 10 when viewed as a total. Therefore, the actual operation mode is provided in order to display only the force loaded on the force indicator 10 purely. That is, in the actual action mode, the state where gravity and the normal drag are balanced is not displayed.

  The mode may be selected by providing the force indicator 10 with a switch that can select either the normal mode or the actual action mode, and depending on the direction of the force indicator 10 when starting up, the normal mode and the actual action mode may be selected. One of them may be automatically selected. As the latter, for example, when the start switch is turned on while the force indicator 10 is in the upright state (the state shown in FIG. 1), the normal mode is selected, and the force indicator 10 is turned upside down (the direction of the z axis is opposite to that in FIG. 1). ), The controller 40 may be programmed so that the actual operation mode is selected when the start switch is turned on.

<Normal mode>
In the normal mode, gravity G is always displayed. However, the display of the short-period acceleration value S varies depending on the direction of gravity G as follows.
When the short cycle acceleration value S is opposite in direction to the gravity G (different sign), both the short cycle acceleration value S and the gravity G are displayed independently. For example, if the short-cycle acceleration value Sx has a size of three LEDs in the positive (+) direction and the gravity Gx has a size of one LED in the negative (−) direction. Three LEDs on the x (+) side of the xz display body 16 are lit, and one LED on the x (−) side of the xz display body 16 is lit.
When the short-cycle acceleration value S has the same direction as the gravity G (same sign), the short-cycle acceleration value S is added to the gravity G and displayed (S + G). For example, suppose that the short-cycle acceleration value Sx has three LEDs in the positive (+) direction and the gravity Gx has one LED in the positive (+) direction. , Four LEDs on the x (+) side of the xz display body 16 are lit.

<Actual mode>
In the actual operation mode, regardless of the direction (sign) of the short cycle acceleration value S, the short cycle acceleration value S is always added to the gravity G and displayed (S + G). For example, gravity G and normal force (short cycle acceleration value S) have different signs, so S + G is 0 (zero). Therefore, nothing is displayed when the force indicator 10 is stationary. However, when the force indicator 10 is freely dropped, the normal force (short cycle acceleration value S) becomes 0 (zero), so that only the gravity G is displayed on the x (−) side of the xz display body 16. become.
In both the normal mode and the actual operation mode, the display based on the gravity G does not change unless the force indicator 10 is tilted, or changes slowly when changing. On the other hand, when the display based on the short-cycle acceleration value S is moved by holding the force indicator 10 by hand, it quickly changes following the movement.

[display]
The controller 40 lights and displays the LED of the display unit 60 based on the display content specified as described above. In the present embodiment, as described above, one LED corresponds to 0.25 g (g = gravity acceleration), and therefore one LED is turned on when the display information is 0.125 g <d ≦ 0.375 g. Similarly, when 0.375 g <d ≦ 0.625 g, two may be lit, and when 0.625 g <d ≦ 0.875 g, three may be lit. When the display information is smaller than 0.125 g, no LED is lit.

[Processing procedure]
The processing procedure of the force indicator 10 by the controller 40 described above will be described based on the flowcharts shown in FIGS.
<Initialization process>
When the activation switch is turned on, the controller 40 performs initialization processing of the force indicator 10. This initialization process is performed to obtain information necessary for performing a series of processes of the force indicator 10, and is performed by executing the steps S101 to S109 of FIG.
When the activation switch is turned on, the controller 40 samples the acceleration values Ax, Ay, and Az from the acceleration sensor 20 (step S101), and the short-period acceleration values Sx, Sy, and Sz, and the long-period acceleration values Lx, Ly, and Lz. Is calculated (steps S103 and S105). Steps S101 to S105 are performed repeatedly. When Steps S101 to S105 reach a predetermined number of sampling times (n times), the controller 40 indicates that the short-period acceleration values Sx, Sy, and Sz for each number coincide with each other, and Sx and Sy are 0. It is determined whether or not the initialization condition is satisfied, that is, whether or not the force indicator 10 is stationary with the z-axis oriented in the vertical direction (step S107). For example, when the force indicator 10 is held and moved, any one of the short-period acceleration values Sx, Sy, and Sz fluctuates, so that it is determined that the initialization has failed (No in step S107). The processing from S101 to step S105 is performed until the predetermined number of times of sampling (n times) is reached, and the determination of step S107 is performed.

  In step S107, when it is determined that the initialization condition is satisfied (step S107 Yes), the controller 40 stores the acceleration value Lz0 sampled in the n-th time in the z-axis direction as the above-described reference gravity G0 (G0 = Lz0). (Step S109). This completes the initialization process (step S111 in FIG. 3). Note that the short cycle acceleration values (Sx, Sy, and Sz) and the long cycle acceleration values (Lx, Ly, and Lz) at the time when the initialization is completed are held as they are without being stored in the memory. The long-period acceleration values (Lx, Ly, and Lz) are newly calculated when it is determined as non-acceleration motion (Yes) in step S121 described later. In addition, when it is broken with acceleration motion (No) in step S121, which will be described later, it is further maintained as it is.

<Sampling and calculation for display>
When the initialization is completed, the acceleration values Ax, Ay, and Az are sampled from the acceleration sensor 20 (step S113), and the short cycle acceleration values Sx, Sy, and Sz, and the long cycle acceleration values Lx, Ly, and Lz are calculated (step S113). Steps S115 and S117).
Controller 40, short period acceleration value Sx calculated from Sy and Sz, the absolute value ^G1 of the acceleration ^{(G1 = (Sx 2 + Sy} 2 + Sz 2) 1/2) was calculated (step S119), then the calculated The absolute value G1 of the acceleration and the reference gravity G1 stored with the initialization are compared (step S121). If the force indicator 10 is not accelerating, G1 remains G0, so G1 coincides with G0 (G1 = G0, Step S121 Yes), and if the force indicator 10 is accelerating, G1 is It is different from G0 (G1 ≠ G0, step S121 No). However, since there is a measurement error, it is a realistic process to set a certain threshold value α and to determine that non-acceleration motion is performed if | G0−G1 | <α. ^{Further, (Sx 2 + Sy 2 +} Sz 2) in order to omit the calculation of ^1/2), G0 ² and G1 ² may of course be compared.

  As described above, in the case of Case-A (non-acceleration motion), the controller 40 stores Gx = −Lx, Gy = −Ly, and Gy = −Lz in the memory (step S123), and Case-B (acceleration). In the case of motion, the preceding long-period acceleration values (Lx, Ly, and Lz) are held without performing special processing (steps S121 to S125).

Next, the controller 40 determines which of the normal mode and the actual operation mode is selected for the force indicator 10 (step S125).
When the normal mode is selected, the processing following (A) of FIG. 4 is performed. In the case of the normal mode, it is determined whether the short-cycle acceleration value S and the direction of gravity G are different (step S201). If the direction is opposite (Yes in step S201), the short cycle acceleration value S and the gravity G are independently used as display information (step S203). If the direction is the same or at least one of the values is 0 (No in step S201), the short period acceleration value S is added to the gravity G (S + G) to obtain display information.
On the other hand, when the actual operation mode is selected, the processing following (B) in FIG. 4 is performed. In this case, regardless of the direction (sign) of the short cycle acceleration value S, the short cycle acceleration value S is always added to the gravity G (S + G) to obtain display information (step S207).
The controller 40 lights and displays the LED of the display unit 60 based on each display information (step S209).

  When the process up to step S209 is completed, the controller 40 returns to step S111 in FIG. 3 ((C) in FIGS. 3 and 4), and repeats the process from step S111 to step S209, so that the state of the force indicator 10 The display unit 60 is caused to display in accordance with the change of. Although the repetition cycle is arbitrary, for example, the processing from step S111 to step S209 can be repeated at a frequency of about 30 to 50 times per second.

[Display example]
Now, an example of actually visualizing and displaying the force using the force indicator 10 will be described in the following order.
(I) Still on the horizontal plane (normal mode) ... FIG. 6, FIG. 7, FIG.
(II) Free fall (or throwing up, normal mode) ... Figure 8
(III) Linear acceleration motion on the horizontal plane (with external force, normal mode) ... Fig. 9
(IV) Constant-velocity linear motion on the horizontal plane (no external force, normal mode) ... Fig. 10
(V) Still on the inclined surface (normal mode) ... Fig. 11
(VI) Free sliding on the inclined surface (normal mode) ... Release of static state ... Fig. 12
(VII) Rotational motion (normal mode) ... FIG.
(VIII) Stationary → Free fall motion (actual action mode) ... Fig. 15
(IX) Stationary → artificially oscillate up and down (normal mode) ... Fig. 16

(I) Resting on a horizontal plane ... Figs.
When the force indicator 10 in the normal mode is stationary on the horizontal plane, gravity and vertical drag from the horizontal plane act on the force indicator 10. Gravity acts downward in the z-axis direction, and normal drag acts upward in the z-axis direction. However, gravity cannot be measured by the acceleration sensor 20 of the force indicator 10. Therefore, the force indicator 10 displays the force in the opposite direction as gravity using the long-period acceleration value Lz of the acceleration measured by the acceleration sensor 20.
When the force indicator 10 is stationary on the horizontal plane, gravity and normal drag are balanced, and the xz display 16 has four LEDs on the positive (+) side in the z-axis direction and negative ( The four LEDs on the − side are turned on (FIG. 6A).
Four lit LEDs on the positive (+) side represent vertical drag, and four lit LEDs on the negative (−) side represent gravity. A person who has seen this is the object (force indicator 10 ), It can be visually recognized that gravity and normal force are acting.

Contrast the short cycle acceleration value S (hereinafter, the short cycle acceleration value may be omitted) and the long cycle acceleration value L (hereinafter, the long cycle acceleration value may be omitted) displayed as described above. And shown in Table 1 below. In Table 1, what is described in the column of initialization is information at the time when initialization is completed. In Table 1, it is assumed that NS and NL acceleration values A have been measured when initialization is completed.
In this example, since it is stationary on the same horizontal plane from the time of initialization and Lz at the time of initialization is g (gravity acceleration), Gz0 is stored as -g.
The force indicator 10 remains stationary after the initialization is completed, but during that time, the determination of non-acceleration motion or acceleration motion in S121 of FIG. 3 is always Yes, so Sx and Lx, Sz and Lz always have the same value. . That is, both Sz and Lz remain g. In this case, it is determined that the force indicator 10 is in a non-accelerated motion state, and Gz0 = −Lz0 = −g is handled as display information. Therefore, Sz = g (positive) and Gz0 = −g (negative) are acceleration information independently. As a result, four LEDs on the positive (+) side in the z-axis direction are also negative. The four LEDs on the (−) side are turned on. In addition, since no force is acting in the xy direction on the force indicator 10 stationary on the horizontal plane, none of the LEDs of the xy display body 17 is lit (FIG. 6B).

  As shown in FIG. 7, the force indicator 10 can display that the gravity and the normal force are balanced even if the direction of the force indicator 10 is changed to stand still. For example, as shown in FIG. 14, even if the force indicator 10 is rotated clockwise and the x-axis is in the vertical direction, gravity and normal drag can be shown. This is because the force indicator 10 generates display information based on the short cycle acceleration value S and the long cycle acceleration value L calculated for each of the three axes. That is, the force indicator 10 has an isotropic property that can be used without being restricted by the orientations of the x-axis, y-axis, and z-axis. The same applies to the case after the following (II) free fall (or throwing up).

(II) Free fall (or throwing up) ... Figure 8
When the normal mode force indicator 10 in the upright state is allowed to fall freely, the normal drag that was acting when the force indicator 10 was placed on a horizontal plane does not act. However, gravity acts on the force indicator 10. Accordingly, as shown in FIG. 8A, only the four LEDs on the negative (−) side in the z-axis direction of the xz display body 16 have to be lit.
The four LEDs facing downward (− side) represent gravity, and a person who sees the LED can visually recognize that only gravity acts on the object (force display 10) during free fall.
Similarly, when the force indicator 10 is thrown up, similarly, only four LEDs on the negative (−) side in the z-axis direction of the xz display body 16 are lit.

Table 2 below compares the short cycle acceleration value S and the long cycle acceleration value L when displayed as described above. Note that the force indicator 10 is stationary on a horizontal plane until initialization is performed, and Gz0 is stored as Gz0 = −g at the time of initialization.
When the acceleration sensor is free-falling (or thrown up), the inertial force and gravity cancel each other, so that the output of the acceleration sensor in the vertical direction becomes 0 (zero). That is, G0 ≠ G1 is satisfied. Therefore, since the controller 40 determines that the force indicator 10 is accelerating (No in S121 in FIG. 3), Lx and Lz (Gx, Gz) precede, that is, Lx at the time of completion of initialization. , Lz (Gx, Gz) is held (→ in Table 2). In addition, it is shown by an arrow (→) that the long-period acceleration value L that precedes Table 3 is also held. On the other hand, from the previously stored Gz = −g and Sz = 0, the display information in the z-axis direction becomes Sz + Gz = −g + 0 = −g, and the negative (−) side of the xz display body 16 in the z-axis direction. Only the four LEDs are turned on.

(III) Linear acceleration motion on the horizontal plane (with external force) ... Fig. 9
For example, when the force indicator 10 in the normal mode performs linear acceleration motion on a horizontal plane while being pressed by a hand, an external force F directed to the left in the figure in the x-axis direction acts on the force indicator 10. Accordingly, as shown in FIG. 9A, for example, three LEDs on the positive (+) side in the x-axis direction of the xz display body 16 are turned on. In this case, the three LEDs that are lit indicate that the magnitude of the acceleration corresponding to the external force F is about 3/4 of g (gravity acceleration).
Further, when the force indicator 10 accelerates on the horizontal plane while receiving the external force F, the force indicator 10 is subjected to gravity and vertical drag from the horizontal plane. Therefore, in the xz display body 16, four LEDs on the positive (+) side in the z-axis direction and four LEDs on the negative (−) side in the z-axis direction are turned on.
As described above, the three LEDs on the positive (+) side in the x-axis direction of the xz display body 16 represent the external force F, the four LEDs on the positive (+) side represent the vertical drag, and the negative (− The four LEDs on the) side represent gravity, and a person who has seen this is acting on the object (force indicator 10) with external force F, gravity and vertical drag in the rightward horizontal direction acting on the force indicator 10. Can be recognized visually.

Table 3 below compares the short cycle acceleration value S and the long cycle acceleration value L when displayed as described above. Note that the process up to initialization is the same as described above.
When moving from a stationary state (non-acceleration motion) to a linear acceleration motion, a horizontal external force F is applied to the force indicator 10 to generate acceleration in the x-axis direction. Of course, G0 ≠ G1 is satisfied. Therefore, since the controller 40 determines that the force indicator 10 is accelerating (No in S121 in FIG. 3), Lx and Lz (Gx, Gz) precede, that is, Lx at the time of completion of initialization. , Lz (Gx, Gz) is held (→ in Table 3). On the other hand, since Gz = -g and Sz = g stored previously have opposite directions, Sz (g) and Gz (-g) are independently display information in the z-axis direction, and xz Four LEDs on the positive (+) side and the negative (−) side in the z-axis direction of the display body 16 are turned on. Also, since Sx = 0.75g and held Lx = 0, the display information in the x-axis direction is Sx + Lx = 0.75g + 0 = 0.75g, and the three LEDs on the positive (+) side in the x-axis direction are Illuminated.

(IV) Constant-velocity linear motion on the horizontal plane (no external force) ... Fig. 10
When the force indicator 10 in the normal mode moves at a constant linear velocity on the horizontal plane, as shown in FIG. 10, only gravity and vertical drag from the horizontal plane act on the force indicator 10.
Therefore, in the xz indicator 16, four LEDs on the positive (+) side in the z-axis direction and four LEDs on the negative (−) side in the z-axis direction are lit. Four LEDs on the positive (+) side represent vertical drag, and four LEDs on the negative (−) side represent gravity, and a person who has seen this is subject to gravity and vertical on the object (force indicator 10). It can be visually recognized that the drag acts on the force indicator 10.
The short-cycle acceleration value S and the long-cycle acceleration value L when displayed as described above are the same as in the case (I) where the short-cycle acceleration value L is stationary on a horizontal plane.

(V) Still on the inclined surface ... Fig. 11
As shown in FIG. 11, when the force indicator 10 in the normal mode is held by the support 70 on the inclined surface and is stationary, the force indicator 10 has a gravity component in each of the x-axis and z-axis directions. The vertical drag received from the inclined surface and the support 70 acts. However, here, it is assumed that no friction acts between the inclined surface and the force indicator 10. In this case, the force is balanced between the x-axis and the z-axis. The force indicator 10 receives a drag D from the support 70 in the horizontal direction with respect to the inclined surface. This drag D is equal in magnitude and opposite in direction to the x-axis component of gravity.

  Therefore, in the xz display body 16, for example, three LEDs on the positive (+) side in the z-axis direction and three LEDs on the negative (−) side in the z-axis direction are turned on. In the xz display body 16, two LEDs on the positive (+) side in the x-axis direction and two LEDs on the negative (−) side in the x-axis direction are lit. A person who sees this shows that gravity and normal drag act on the object (force indicator 10) in the x-axis direction and the z-axis direction, and that the forces are balanced in the x-axis direction and the z-axis direction, respectively. Can be visually recognized.

In this example, it is assumed that the force indicator 10 standing upright at the time of initialization is tilted after the initialization. Further, it is assumed that the operation of tilting the force indicator 10 that is standing up (inclination process in Table 4) is performed by a non-acceleration motion that takes about 5 seconds. The short cycle acceleration value S and the long cycle acceleration value L from initialization to support on the inclined surface are shown in Table 4 below.
In the tilting process, since the force indicator 10 is performing non-acceleration motion (Yes in S121 in FIG. 3), Sx, Sz, Lx, and Lz are sequentially changed according to the tilt. Specifically, Sx and Lx increase from the initialization time, and Sz and Lz decrease sequentially from the initialization time. In this tilting process, since Sx and Gx have opposite directions, Sx and Gx become display information independently. Although the description of FIG. 11 is omitted, for example, when Sx = 0.1 g and Gx = −0.1 g, the number of LEDs lit in the x-axis direction is 0, and Sx = 0.2 g, Gx = When -0.2 g, Sx = 0.3 g, and Gx = -0.3 g, the number of LEDs lit in the x-axis direction is 1, and when Sx = 0.4 g and Gx = -0.4 g The number of LEDs lit in the x-axis direction is 2. In addition, when Sz = 0.99 g to 0.92 g and Gz = −0.99 g to −0.92 g, the number of LEDs lit in the z-axis direction remains four.
When the force indicator 10 is maintained (still) for a certain time after being tilted to a predetermined angle, the force indicator 10 remains in a non-accelerated motion (Yes in S121 in FIG. 3). Then, since Sx = 0.5 g, Sz = 0.87 g, Lx = 0.5 g, and Lz = 0.87 g are obtained according to the inclination angle, Gx0 = −0.5 g and Gz0 = −0.87 g are obtained. Treated as display information. Therefore, Sx = 0.5 g (positive) and Gx = −0.5 g (negative), and Sz = 0.87 g (positive) and Gz = −0.87 g (negative) are each independently acceleration information. As a result of the treatment, two LEDs on the positive (+) side and negative (−) side are lit in the x-axis direction, and three LEDs on the positive (+) side and negative (−) side in the z-axis direction. Lights up.

(VI) Free sliding on the inclined surface ... Fig. 12
When the force indicator 10 in the normal mode freely slides on an inclined surface having no friction, the force indicator 10 is subjected to gravity and a normal force from the inclined surface. The normal force received from the inclined surface has the same magnitude as the z-axis direction component of gravity, that is, the acceleration information Az in the z-axis direction, and has the opposite direction.
Since the force indicator 10 freely slides on the inclined surface, the force received is three components, ie, the x-axis direction component of gravity, the z-axis direction component of gravity, and the normal force received from the inclined surface.

  Therefore, for example, three LEDs on the positive (+) side in the z-axis direction and three LEDs on the negative (−) side in the z-axis direction are lit on the xz display body 16. Further, in the xz display body 16, for example, two LEDs on the positive (+) side in the x-axis direction are turned on. A person who sees this shows that the Z component of the gravity and the normal drag are acting on the object (force display 10) in the z-axis direction, and the x component of the gravity is acting in the x-axis direction. It can be visually recognized that the vessel 10 is accelerated by the x-axis component of gravity.

In this example, as shown in FIG. 12, first, the support body 70 that has supported the force indicator 10 is removed, and free sliding is performed. Therefore, the situation before removing the support 70 is the same as that of the inclined surface support.
After the support 70 is removed, the force indicator 10 does not receive the drag D from the support 70, so Sx = 0 as shown in Table 5. Also. Since the force indicator 10 performs acceleration motion (No in S121 in FIG. 3), Lx and Lz (Gx, Gz) precede, that is, Lx and Lz (Gx, Gz) at the completion of initialization are held (Table 5 →), Gx0 = −0.5 g, and Gz0 = −0.87 g are treated as display information. Therefore, Sz = 0.87g (positive) and Gz = −0.87g (negative) are treated as display information independently, and as a result, two LEDs on the positive (+) side are lit in the x-axis direction. In the z-axis direction, the three LEDs on the positive (+) side and the negative (−) side are turned on.

(VII) Rotating motion ... Fig. 13
When the force indicator 10 in the normal mode is placed on the end of a disk 70 that can freely rotate around the axis S as shown in FIG. 13A and the disk 70 is rotated, a centripetal force acts on the force indicator 10. The LED is lit as in 13 (b). In general, it is considered that centrifugal force acts on a rotating object, and actually centrifugal force acts on a rotating coordinate system. However, centripetal force is necessary for the force indicator 10 placed as shown in FIG. 13 (a) to make a circular motion with the disk. It is usually very difficult for students to understand this relationship. By using the present invention, it can be clearly shown that the centripetal force is acting on the rotating object.

(VIII) Stationary → Free fall motion (actual action mode) ... Fig. 15
As shown in FIG. 15, it is assumed that the force indicator 10 (the upper stage in FIG. 15) in the actual operation mode that is supported horizontally and stationary is released to fall freely (the lower stage in FIG. 15).
In the supported state, none of the LEDs of the xz display body 16 is lit. This is because the actual action mode avoids the display of balanced gravity and normal force. However, when the free fall starts, four LEDs on the negative (−) side in the z-axis direction of the xz display body 16 are turned on, indicating that gravity acts on the force indicator 10.
In this way, by adopting the actual operation mode, it is possible to avoid displaying the force (acceleration) that is not applied to the force indicator 10 as a whole by balancing as in the stationary state, but the force at the time of free fall. It can be shown that gravity is applied to the display 10. By comparing the display of the force indicator 10 in the normal mode and the actual action mode, the understanding of the force applied to the object can be deepened.

  In this example, it is supported on a horizontal plane until it falls freely, and as shown in Table 6, Sz = g and Gz = −g. However, since the actual load mode (the display information is always Sz + Gz), the display information while being supported on the horizontal plane is Sz + Gz = g + (− g) = 0. When the support to the horizontal plane is released, there is no vertical drag, so Sz = 0. As a result, in the case of free fall, 4 on the negative (−) side in the z-axis direction corresponds to Gz = −g. One LED is lit.

(IX) Stationary → artificially oscillate up and down (normal mode) ... Fig. 16
As shown in FIG. 16 (a), the normal mode force indicator 10 that is horizontally supported and held (stationary) is instantaneously lowered to the position shown in FIG. 16 (b). It shall be raised to the position of 16 (c).
In the held (static) state, it is the same as that supported by the horizontal plane of (I), so the xz display body 16 has four LEDs on the positive (+) side in the z-axis direction, Further, the four LEDs on the negative (−) side in the z-axis direction are turned on (FIG. 16A). Four lit LEDs on the positive (+) side correspond to vertical drag, and four lit LEDs on the negative (−) side correspond to gravity.
When it is momentarily lowered from the holding state, the vertical drag is lost, and the positive (+) side LED in the z-axis direction is not lit. In addition, when an external force directed downward is applied, five LEDs are lit on the negative (−) side in the z-axis direction (FIG. 16B).
Furthermore, since the upward force is applied when turning from descending to ascending, only one LED corresponding to the upward force is lit on the positive (+) side in the z-axis direction. On the negative (−) side in the z-axis direction, four LEDs corresponding to gravity are lit (FIG. 16C).

Table 7 below compares the short cycle acceleration value S and the long cycle acceleration value L when displayed as described above.
In this example, it is held horizontally until descending / rising, that is, until vibration starts, and Sz = g and Gz = −g, corresponding to the positive (+) side and negative (−) in the z-axis direction. 4 LEDs on both sides are lit.
While descending momentarily, it receives downward force. This downward force corresponds to 0.25 g. Although the short cycle acceleration value S follows the instantaneous fall, but the long cycle acceleration value L does not follow, the short cycle acceleration value becomes Sz = −025g, whereas Gz remains −g. It is. In the display information, since Sz and Gz have the same direction, Sz + Gz = −1.25 g.
While being raised momentarily, it receives upward force. It is assumed that this upward force corresponds to 0.25 g. Then, the short-period acceleration value becomes Sz = 025 g, while Gz remains −g. Since Sz and Gz have opposite directions, each of Sz = 0.25 g and Gz = −1 becomes display information.

Although the embodiments of the present invention have been described above, the acceleration sensor 20 may be an acceleration sensor having an analog output. However, in this case, it is necessary to provide other elements such as a filter / amplifier circuit.
Moreover, although the rectangular parallelepiped case 11 was used for the force indicator 10, this invention is not limited to this. As long as two display surfaces, an xz display surface and an xy display surface, can be formed, for example, the case 11 may be a polygon more than a quadrangle or may be a sphere.
Furthermore, regarding the xz display body 16 and the xy display body 17, LEDs of different sizes may be arranged, and positive / negative can be displayed for each of the three axes (x axis, y axis, z axis). What is necessary is just to be a thing, and it is not limited to arranging LED in a cross shape.
Furthermore, instead of using the display information as it is, for example, by providing a mode in which the display information is displayed twice, it is possible to improve the visibility when a small force is applied.
In addition to this, as long as it does not depart from the gist of the present invention, the configuration described in the above embodiment can be selected or changed to another configuration as appropriate.

DESCRIPTION OF SYMBOLS 10 ... Force indicator 11 ... Case 12 ... xz display surface, 13 ... xy display surface 14 ... xz display substrate, 15 ... xy display substrate 16 ... xz display body, 17 ... x- y display body 20 ... 3-axis acceleration sensor, 40 ... controller, 60 ... display unit

Claims (7)

A triaxial acceleration sensor that detects acceleration in each of the x-axis direction, the y-axis direction, and the z-axis direction orthogonal to each other;
Based on the acceleration in the x-axis direction, the y-axis direction, and the z-axis direction acquired from the triaxial acceleration sensor, corresponding to forces other than gravity acting on the triaxial acceleration sensor in each of the axial directions Obtaining acceleration information S (Sx, Sy, and Sz) and acceleration information L (Lx, Ly, and Lz) corresponding to gravity acting on the three-axis acceleration sensor,
A controller that generates display information for each of the axial directions based on the calculated acceleration information S (Sx, Sy, and Sz) and the acceleration information L (Lx, Ly, and Lz);
A display for displaying the direction and magnitude of the force acting in the axial direction based on the display information;
A visual force indicator characterized by comprising: The controller is
Reference gravity G0 specified after startup,
Absolute value G1 of acceleration calculated from the acceleration information S (Sx, Sy and Sz) calculated after specifying the reference gravity G0 (where absolute value of acceleration G1 = (Sx ² + Sy ² + Sz ² ) ^{1 / 2} to determine whether the visual force indicator is in an accelerated or non-accelerated state.
The visual force indicator according to claim 1. The controller is
If it is determined that the visual force indicator is in a non-accelerated motion state,
An acceleration value G (Gx = −Lx, Gy = −Ly and Gz = −Lz) whose direction is opposite to that of the acceleration information L (Lx, Ly and Lz) is applied to the triaxial acceleration sensor. As the display information corresponding to
If it is determined that the visual force indicator is in an acceleration motion state,
The acceleration information G (Gx = −Lx, Gy = −Ly and Gz = −Lz) having the opposite direction and the same magnitude as the acceleration information L (Lx, Ly and Lz) before the acceleration motion is started, Treated as the display information corresponding to gravity acting on the three-axis acceleration sensor,
The visual force indicator according to claim 2. The controller is
A first mode and a second mode for displaying the direction and magnitude of the force;
The first mode is:
When the directions of the gravity G (Gx = −Lx, Gy = −Ly and Gz = −Lz) and the acceleration information S (Sx, Sy and Sz) are opposite, the gravity G and the acceleration information S are Treated as independent display information,
When the direction of the gravity G (Gx = −Lx, Gy = −Ly and Gz = −Lz) and the acceleration information S (Sx, Sy and Sz) are the same, the gravity G and the acceleration information S are added. Treated as the display information,
The second mode is:
Regardless of the direction of the gravity G (Gx = −Lx, Gy = −Ly and Gz = −Lz) and the acceleration information S (Sx, Sy and Sz), the gravity G and the acceleration information S are added and the Treat as display information,
The visual force indicator according to claim 3. The controller is
Prior to specifying the reference gravity G0, the acceleration information L (Lx, Ly and Lz) is calculated,
The initial gravity values Gx0 = −Lx0, Gy = −Ly and Gz = −Lz) are stored according to the acceleration information L0 (Lx0, Ly0 and Lz0) in the respective axial directions given when the reference gravity G0 is specified.
The visual force indicator according to any one of claims 1 to 4.   A visual science teaching material comprising the visual force indicator according to any one of claims 1 to 5.   A visual scientific toy comprising the visual force indicator according to any one of claims 1 to 5.

Images