JPS6067816A - Position measuring apparatus - Google Patents

Abstract

PURPOSE:To measure and display positions and directions as results of arbitrary motions, by computing instantaneous displacement by integrating acceleration data. CONSTITUTION:A portable position measuring apparatus 1 is meant for confirmation of the existing position when a man takes a walk or he is on his hiking course or for knowledge of a distance covered by him and a direction in which he is oriented, and composed of acceleration sensor element, display unit 2 and computing circuit. The sensor is constructed by sensors X1 and X2 detecting acceleration in the direction X, sensor Y detecting acceleration in the direction Y, and sensor Z detecting acceleration in the direction Z. The computing circuit integrates the acceleration data detected by each sensor, computes instantaneous velocity and displacement and transmits the results to the display unit 2. The display unit 2, basing upon this transported data, displays the instantaneous velocity and displacement by numerals and figures.

Description

[Detailed description of the invention] The present invention relates to a portable position measuring device.

People naturally want to check their current location when walking, hiking, hiking, looking for a place on a map, or while driving in a car, and they want to know the distance they have traveled and the direction they are currently heading. There was no suitable measuring device to meet such a desire.

An object of the present invention is to provide a position measuring device that can meet such demands for knowing information such as the position and direction as a result of arbitrary actions. The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a perspective view of an embodiment of the present invention. 1 is the case of the device, which fits in the chest pocket of clothes like a small calculator and moves with the pedestrian. 2 is a liquid crystal display device that displays measurement results on one screen.

3 is a start switch that is pressed when starting measurement.

If pressed during measurement, the screen will change. 4 is a switch that is pressed at the end of the measurement to enable the primary restart, and is a depressed button to prevent erroneous operation. 5 is a magnetic needle provided to confirm the direction, 6 is a slit into which a reference map is inserted, and the inserted map is displayed on the liquid crystal display device 2.
It is possible to see through it. 7 is an element like a mercury switch that detects the attitude of the device, when the device is tilted so much that accurate acceleration components cannot be measured.

The buzzer is designed to emit a warning sound to notify the user. x, y, and z are coordinate axes fixed to the case of the device, and are used to explain the operation below. XI,X
2 and Y are acceleration sensors, and both sensors XI and X2 are fixed in the case 1 in a direction such that acceleration is felt in the X direction, and sensor Y is fixed in a direction such that acceleration is felt in the X direction. . Also sensor X1
and X2 are placed a predetermined distance apart to detect rotation of the device around two axes.

Fig. 2 shows an example of the screen of the liquid crystal display device 2, and Fig. 2(a) shows the elapsed time from the start, the average speed of movement,
The distance traveled and the component of the distance displaced by the movement relative to the coordinates fixed on the ground with the starting point as the origin are displayed numerically. Figure (b) shows the horizontal component of the wake from the starting point to the current location. It is a map shown at a certain scale, and by superimposing it on a map of the same scale and looking through it, you can immediately know where you have reached. Display (a) and display (b) are switched by a changeover switch 3. The image is displayed either by a single-layer dosotomatrix liquid crystal display or by a multi-layer liquid crystal display consisting of a numeric/character segment display layer and a donmatrix display layer.

FIG. 3 is an exploded oblique view showing the structure of a capacitive element for an acceleration sensor used in the present invention. This is a diagram M. 20 is a substrate made of glass, ceramic, printed board, silicon, metal, etc.; 21
22 is a fixed electrode made of a conductive thin film provided on its surface (not necessary when the substrate is conductive); and 22 is a pattern of its lead line.

19 is a spacer film, and 14 is a metal thin film.

Windows 15, 16 are punched out by etching, resulting in a movable plate 18 supported by a spring part 17.
is formed. Reference numeral 11 denotes a lid of the element made of an insulating material, and has a concave portion that does not hinder the movement of the movable electrode plate 18. 13 is a conductive pattern that contacts the metal plate 14 and serves as a lead line thereof.

By stacking and joining each of the above parts in the direction shown (preferably by creating a vacuum inside), the air resistance of the movement of the movable electrode plate is eliminated, but in order to prevent undesirable vibration of the electrode plate, (A suitable amount of gas may be enclosed as a damping element.) One capacitive element 23 is constructed. The movable electrode plate 18 is cantilevered by the spring portion 17 and faces the fixed electrode plate at an interval equal to the thickness of the spacer 19. This element has an acceleration sensitivity direction in a direction perpendicular to the plane of the thin metal H@14. That is, when the element 23 moves with upward acceleration together with its carrier (such as a circuit board, not shown), the centers of the bipolar plates approach each other, increasing the capacitance of the element, and conversely, when the element 23 has downward acceleration, the centers of the bipolar plates move closer together. The capacitance of the element decreases as the distance increases. Incidentally, since it is undesirable if the movable electrode plate 18 vibrates during acceleration measurement, its natural frequency is set as high as possible. (Preferably, the frequency is at least 300 Hz or more.) This capacitive element is manufactured by applying the integrated surface IpF manufacturing technology. The use of so-called microtechniques, mainly thin film formation technology and photoetching technology, is effective in reducing the size of devices and increasing their natural frequencies.

FIG. 4 shows an oscillation circuit that serves as an acceleration sensor.

C is the same as the capacitive element 23. R is a resistor for providing a predetermined time constant, and these resistors are connected to the NAND circuit 31. It is incorporated into the feedback loop of inverters 32 and 33 to constitute an oscillation circuit, P is a terminal for ON-FF control of oscillation, and Q is an output.

Although the oscillation frequency changes depending on the capacitance value of C, a range that can be considered to be approximately linear with respect to the acceleration of this change is used.

Figure 5 shows multiple acceleration sensors Xi using one oscillation circuit.
X2. An example of a circuit that drives Y and Z is shown. R1, R2
, R3, and R4 are resistive elements combined with their respective capacitive elements, and 34 is a switching circuit that has a shift input terminal 35. Internally, as in this example, there are 4 bits corresponding to the four acceleration sensor elements. It is composed of a group of transmission gate circuits controlled by a shift register, and only one capacitive element is connected to an oscillation circuit at a time, and each time there is an input to a terminal 35, the capacitive elements in an oscillating state are switched in a predetermined order. In this embodiment, the acceleration in each direction is sampled sequentially, so there is no need to keep several oscillation circuits operating all the time, and by using two circuits as shown in the figure, it is not only economical in terms of current consumption. Moreover, it has the advantage that compensation for changes in oscillation frequency with respect to temperature and voltage, non-linearity of output frequency with respect to acceleration, etc., need only be performed for one oscillation circuit.

FIG. 6 is a block diagram of the circuit system of this embodiment. 41 is a plurality of acceleration sensor oscillation circuits, 42
is the acceleration measurement circuit, and the oscillation frequency of one of the sensors is
It mainly consists of a counter that counts the difference from the rest state, and a memory that stores the count results. A timing control circuit 43 controls the selection of measurement sensors and the operation timing of calculations to be described later. 44 corresponds to switches 3 and 4 in FIG. This is a switch for manually controlling the device. 45
receives measurement data from the acceleration measurement circuit, integrates it, calculates momentary velocity and displacement, and displays the results on the display device 46.
This is an arithmetic display circuit that outputs data to

FIG. 7 is a diagram illustrating the acceleration calculation method performed in this device. N-8, E-W indicate the direction. (2) is the device at the starting point, and at the time of departure, the y-axis of the device is accurately directed toward north (N), for example, using the magnetic compass 5. Now, suppose that the device follows an arbitrary path as indicated by the dotted line (arrow), and during that time it tilts by an angle θ and reaches the position 1'.

(It is assumed that the device is moved while keeping the two axes in the vertical direction.) At this time, the acceleration felt by sensor X1 having sensitivity in the X direction is XI, and the acceleration felt by sensor Y having sensitivity in the y direction. If the acceleration acting on the device is Y, then the absolute accelerations AX (W-E direction) and AY (S-N direction) acting on the device are respectively AX=Xlcosθ−Y sinθ (1
AY =
Sensitivity and distance%! It is determined by It. ) as.

ΔΩ−B (XI−X2) (,3). Note that the absolute acceleration in the vertical direction (height direction) is equal to the acceleration felt by the sensor Z, which is sensitive in two directions, on the premise that the device does not tilt much.

All that is left to do is to perform numerical refinement every moment using these basic formulas and calculate each component of velocity and displacement.

FIG. 8 shows a flowchart for the calculation.

Figure (a) shows the flow of acceleration measurement for each sensor.

First, in block 50, the oscillation circuit oscxi including the sensor element X1 is activated. (A signal for opening the gate is given to the control terminal 33 in FIG. 4.) Next, wait a predetermined time until the oscillation exits the transient state. The oscillation frequency is measured (this is basically the same for period measurement), and the count value of frequency deviation proportional to acceleration is measured by a counter circuit and stored in memory X1.

The block 60 includes sensor X2 0
The oscillation is switched to 3CX2 and data is stored in the memory X2 in the same manner. In the next block 7°, we will talk about oscy and memory Y.

Furthermore, in block 80, the same operation is performed for oscz and memory Z. In block 90, a time wait is performed so that one cycle of measurement coincides with a predetermined time. Further, the above-described cycle is repeated unless it is detected that the measurement end switch is pressed in block 1°O.

Let's now quantitatively consider the conditions required for sensors and measurement systems. The sensitivity required to detect acceleration changes during walking and calculate sufficiently accurate displacement is approximately 0.
- Desirably 0IG (G is gravitational acceleration) or higher. Furthermore, if the sampling interval is too long, it will not be possible to faithfully track minute changes in acceleration, so it is desirable that the measurement cycle be about 0.1 seconds or less. That is, 1
The measurement time allocated to each sensor is still 0.0
It is on the order of 1 second. The sensitivity of the capacitance change of the sensor element shown in FIG. 3 is approximately a few percent per IG, and therefore the rate of change of the oscillation frequency is also the same. Now, let's assume that the oscillation frequency of the sensor without acceleration is I M
Hz, the frequency count value during the measurement time assigned to that sensor, for example 0.01 seconds, is 100.
00, and if the sensitivity of the sensor is 2% per IG, the change in count for an acceleration change of 0.01G will be 10000*0.02*0.01-2, so the oscillation frequency should be about I M H2 or more. You can expect measurements with very good accuracy. Of course, depending on the accuracy, or depending on the sensitivity of the sensor,
Lower frequencies (eg, below 100 KHz) or higher frequencies (eg, above 10 MHz) can be used. Furthermore, instead of measuring the oscillation frequency and wave number of this sensor-equipped oscillator, its period (including frequency division) may be measured using another reference frequency source. However, in this case, the relationship between the increase/decrease in count and the magnitude of acceleration is reversed from the previous case. Further, a charging/discharging circuit may be constructed by combining the sensor element as described above with a resistor, and a sensor may be constructed that measures charging or discharging time that changes depending on acceleration at a different clock frequency.

FIG. 8(b) shows a flowchart for calculating speed, distance, and angle using the acceleration data measured by the system shown in FIG. 8(a). The numerical integration performed here is performed by simply adding minute elements one after another. When the start button to start measurement is pressed, first, in block 110, the memories VX, VY, VZ, DX containing the integrated values are
, DY, DZ, Ω, θ, and L are cleared. (The name of each memory also indicates the numerical value stored in it.

In each case, VX is the absolute velocity in the X direction at the starting point.

vy is the absolute velocity in the Y direction at the starting point, Z is the absolute velocity in two directions, DX is the absolute displacement in the X direction at the starting point, D
Y means the absolute displacement in the Y direction at the starting point, DZ means the absolute displacement in the Z direction, and L means the moving distance.

Next at block 120.

Calculate ΔΩ−B (XI−X2) (3) Ω−Ω+ΔΩ (4) θ=θ+EΩ 〈5) (QLE is a constant of proportionality) and find the angular displacement. Next at block 130.

AX=X1cosθ−Y5ino (6)BX=X]
Absolute acceleration is calculated by sin θ+Y cos θ (7). Next, in Pro Tsuk 140.

VX=VX+AX (8) V Y −V Y + A Y (9) vz=vz+z
(10) Calculate the absolute speed using each formula. Next, in the Pro 2ri 150.

DX=DX+C*VX (11) DY-DY+C*VY (1,2) Dz=I)z+C*vz (13) L=L+C(VX2+VY2)'+ (14) VM=L
/T (15) (where C is a proportionality constant) The absolute displacement in three directions, the moving distance, and the average velocity (VM) are calculated using the following formulas. 100T is the elapsed time from departure, T
A crystal oscillator is used as the reference for the counter. Now a.
All the necessary quantities were given.

Now, in block 160, it is determined whether the user has performed an operation to select either numerical display or map display. Depending on the result, either the block 170 or the block 180 is selected; if the former, the calculation result is displayed numerically as shown in FIG. Graphically displayed at a predetermined scale as shown in Figure (b). The programmer 190 is a timer that creates a waiting time for adjusting the calculation/display cycle to a predetermined time or timing, and is provided as necessary. Progression loop is block 2
If the end of the measurement is not detected at 00, the process returns to immediately before block 120 and repeats the cycle.

The operating functions outlined in the flowchart below are as follows.

At least the main part is an IC of one or several chips.
It is preferable that the sensor elements be assembled together and mounted together with a power supply battery, a sensor element 2 display device, etc. in a storage device.

Next, as another embodiment of the present invention, a modification of the first embodiment described above will be described. For example, the device may have a pocket watch-like appearance, or it may be attached to a wristwatch, or it may be a portable radio or tape recorder.

It may be incorporated into a part of equipment such as a camera. Alternatively, the display device and the main body may be connected with a hinge, and the map may be sandwiched between them, or the main body may be placed on one side of the display device so that the display device is always transparent and overlapped with the map. It's okay. Alternatively, the device may be made more compact by displaying mainly numbers using a small display device. next.

There are already various principles and types of acceleration sensors.2 For example, there are some that output in analog quantities and can be used, but since D/A conversion is required for calculation, the above-mentioned methods are difficult to simplify and reduce power consumption. It is preferable that a digital quantity be directly outputted as in the embodiment. Furthermore, sampling
Regarding the calculation method, whether each sensor element is constantly operated and its output is sampled, or whether it is time-divisionally operated as in the previous embodiment depends on the balance between power consumption and measurement accuracy. Although the integral calculation is performed by simple addition in the embodiment, the Simpson method or other methods for reducing errors may be used. In addition, in the above embodiment, the purpose was achieved with four sensors based on the premise that the device would not be tilted, but if the sensor using a double weight is used, it is possible to perform correction calculations by knowing the diagonal direction and inclination angle of the device with respect to the vertical line. It is also possible to go further and use six sensor elements (element XI, X2 in the above embodiment).
, only the angular acceleration around two axes was detected, but in order to further detect the angular acceleration around the X and y axes, for example, the X2 element parallel to the Z element and separated in the y direction, and the Add X3 elements.

) may be used to detect all the accelerations and angular accelerations in the three axial directions, and calculate the absolute displacement regardless of the orientation of the device, although one calculation becomes quite complicated.

Further, in the above example, some elements for measuring linear acceleration and angular acceleration are used, but these may be separated.

On the other hand, in order to simplify the device, for example, the sensor in the opposite direction may be omitted. In addition, if the device is not stationary at the start, a large calculation error will occur, so a circuit is installed to detect that the acceleration is zero, and the acceleration is not zero within a predetermined short period of time immediately after the start switch is pressed. In this case, please warn the user with a buzzer etc. and try again.

As is clear from the following explanation, the position measuring device of the present invention includes a plurality of acceleration sensors whose output frequency changes depending on the action of an acceleration component in a specific direction, and a counter that measures the frequency or period of the sensor. a measuring means for obtaining momentary acceleration data as a Curran 1-value for each component; and a display device.

It is characterized by comprising a calculation means for calculating momentary displacement by integrating the obtained acceleration data, and a display means for displaying at least the displacement on the screen of the display device using numbers or figures. Because it is a device, it has the effect of meeting a need that could not be fulfilled in the past, such that a user can easily use it and easily know his or her own position and route of movement.

[Brief explanation of the drawing]

Each figure relates to one embodiment of the present invention.
The figure is a perspective view including a partially transparent view, Figures 2(a) and 2(b)
) are front views of the display screen. Figure 3 is an exploded perspective view of the acceleration sensor element, Figures 4 and 5 are acceleration sensor circuit diagrams, Figure 6 is a block diagram of the circuit system, Figure 7 is an explanatory diagram of the acceleration calculation method, and Figure 8 ( a) and (b) are flowcharts of displacement calculation. 1... Device case, 2... Display device, 3, 4...
・Switch, X],,X2. Y, Z, 23... Acceleration sensor element, 50-200... Each stage of calculation. Figure 1 Figure 3 Figure 4 Figure 6 Figure 7 1 (a) Figure 8 (b)

Claims (3)

[Claims] (1) Measurement that uses multiple acceleration sensors whose output frequency changes due to the action of acceleration components in a specific direction, and measures the frequency or period of the sensors using a counter to obtain momentary acceleration data as a count value for each component. a display device; a calculating device for calculating momentary displacement by integrating the obtained acceleration data; and a display device for displaying at least the displacement in numbers or figures on the screen of the display device. A position measuring device characterized by: (2) The position measurement according to claim 1, wherein the main part of the sensor is a capacitive element consisting of a fixed electrode plate and a movable electrode plate that is one-sided and has a support spring. Device. (3) The acceleration measurement directions of at least one set of the plurality of sensors are oriented in two orthogonal directions in the horizontal plane when the position measuring device assumes a normal attitude, and the other set is oriented in the same or the same direction for rotation detection. 2. The position measuring device according to claim 1, wherein the position measuring device is mounted so as to face in opposite directions.