JPH0339610A - Information processing device and its information processing method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention generally relates to an ultrasonic distance measuring device or various applied devices incorporating a distance measuring technique that utilizes the propagation of ultrasonic waves.

[Prior Art] One of the devices devised as an applied device for ultrasonic distance measurement is an ultrasonic coordinate input device. The present invention will be explained below using this device as an example.

FIG. 8 is a schematic diagram of a commonly devised ultrasonic coordinate input device. Reference numeral 1 denotes a coordinate indicating tool (hereinafter referred to as a pen), which is an oscillating tool that has a piezoelectric element incorporated therein and emits a desired ultrasonic signal from its tip. 2a to 2C are sensors, which are receivers that receive ultrasonic signals emitted from a pen via a propagating body. 3 is a propagation body, which serves as a propagation medium for ultrasonic waves, and is made of glass, aluminum plate, or the like. 4 is a vibration isolating material, which is set to prevent reflected waves other than those from the pen 1 from entering the sensors 2a to 2C.
In the ultrasonic coordinate input device having the above configuration,
The coordinates of the indicated point are calculated from the distances between each of the two or more plurality of sensors and the indicated point.

Various methods have been devised to calculate the distance between the sensor and the indicated point, but the basic method is to use a transverse wave whose zero group velocity and phase velocity differ, which is calculated based on the time it takes for the ultrasonic signal emitted from the pen to reach the sensor. When using ultrasonic waves, roughly measure the distance by taking the envelope of the received waveform and finding the group arrival time, and if more precision is required, detect the phase at an appropriate position and calculate the phase arrival time. In order to achieve even finer precision.

Next, a procedure for calculating the distance r between the pen and the sensor from the two time information of the group arrival time and the phase arrival time will be explained. First, when a voltage as shown in FIG. 9 is applied to the piezoelectric element in the pen, the signal received by the sensor becomes as shown in FIG. 10. On the other hand, when the peak position is detected as the group arrival time t3, as shown in FIG. 11, the first stage amplifier 5. Full wave rectifier6. After passing through the low-pass filter 7 and the differentiating circuit 8, the zero crossing of the differentiated signal is detected by the comparator 9, and the time is recognized as the group arrival time tg.

As a result, if the group velocity is υ, then r can be calculated as r=υ,・tg. However, since the method detects time based on the envelope, it is affected by the magnitude of the signal output and the filter characteristics. So, there is inevitably a certain amount of fluctuation Δ
t occurs. Generally, it is possible to obtain a value with less fluctuation by detecting a specific phase zero-crossing point to determine the time.

Therefore, group arrival time 1. If the detection point is defined as the phase zero crossing immediately after the determination, the phase in the group will shift with the distance r because υ, ≠υ, so the phase arrival time tg will be in a stepwise manner as shown in Fig. 12. are observed. This stage indicates the movement of the phase detection point, and the joint between each stage is a parallel shift by the period T of the signal. If υ and υ are equal and a constant phase detection point can always be observed, such a step is not possible and a phase arrival time tg like a straight line a is obtained.

Therefore, it is sufficient to convert the phase arrival time tg obtained stepwise into the original straight line a.

In other words, tp@4(υ, /υp)tx t6t(t or:
offset value) However, since the group arrival time tg has large fluctuations, tg, = nT4 (υg/Vp) tyo toe
Using the property of tp (n is an integer), t pa” t p + T X Int (t pt
/T+O.

5) =tl +TXInt[((υ,/vp) t
gtor to )/T+0. 5] to find tp, and finally calculate r using the following formula.

It can be given by

r=Vp”tpa-rar Crot: offset value)
=Atg+BXInt(Ctg+Dtg+E+0.5)
+F A: υp B: υ, ・T=λ C: (υf/υ,)/T=f(υ, /υ,) D:
-1/T=-f E: -tgr/TF: -rot [Problems to be Solved by the Invention] However, in order to accurately calculate the distance r between the pen and the sensor using the above method, it is necessary to Calculation constants (A, B,
Naturally, the use of C, D, E, F) is a major premise. However, due to the nature of the method that utilizes the propagation of ultrasonic waves, such calculation constants are inevitably subject to slight fluctuations due to the influence of various physical constants and adjustment conditions of individual products. It is virtually difficult to mass produce products with stable coordinate accuracy.

The present invention eliminates the above-mentioned conventional drawbacks and provides an ultrasonic distance measuring device that accurately measures distance regardless of subtle fluctuations due to the effects of various physical constants, adjustment conditions, etc. of individual products.

[Means to be Solved by the Invention] In order to solve this problem, the ultrasonic distance measuring device of the present invention emits ultrasonic waves having different group velocities and phase velocities from an oscillation source, and then transmits them using an ultrasonic sensor. This is an ultrasonic distance measuring device that calculates the distance between the oscillation source and the sensor based on the arrival time of the oscillation source. The present invention is characterized by comprising a correction means for correcting the calculation.

Here, the correction means substitutes the group arrival time t1 and the phase arrival time tg at a predetermined position into a predetermined calculation formula, and calculates the group velocity υ of the calculation parameter used to calculate the distance between the oscillation source and the sensor. , one-phase velocity υp, and frequency f.

Further, the correction means calculates the calculation parameters group velocity υ, 1-phase velocity υp, and frequency f by a predetermined statistical calculation based on the group arrival time t5 and phase arrival time tp observed at arbitrary continuous positions. It is characterized by

Further, the correction means calculates the phase velocity υp of the calculation parameter by substituting the group arrival time tg and phase arrival time tg at a predetermined appropriate position into a predetermined calculation formula, and calculates the phase velocity υp of the calculation parameter. group arrival time tg and phase arrival time t
The method is characterized in that the group velocity υ, which is a calculation parameter, is determined by a predetermined statistical calculation using g.

Further, the correction means corrects the mounting of the sensor using calculation parameters initially set based on the group arrival time t6 and phase arrival time tg at a predetermined appropriate position. The present invention is characterized in that the position is calculated, the amount of deviation from the normal position is calculated, and the correction amount for distance calculation during normal operation is newly set and calibrated.

[Effect] In such a configuration, the group arrival time tg observed at a predetermined appropriate position or any consecutive multiple positions
Calibration is made possible by newly setting calculation constants based on the n-pack arrival time tg, and the optimum calculation constants can be individually set and calibrated for each product.

[Embodiments] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

First Embodiment> FIG. 1 is a diagram showing a configuration example of a calibration pointing point and an ultrasonic coordinate input device in a first embodiment of the present invention. 1 is a vibrating pen, 2 is a sensor, 3 is a diaphragm, and 4 is a vibration isolating material. may be included. lOO is a CPU for calculation control.

101 is a ROM that stores a control program.

102 is an auxiliary storage RAM, for example, constants A and B in this example.
, C, D, and E. 6.103 is an output unit that outputs input coordinates to a display screen or the like.

As mentioned above, the distance r between the pen and the sensor is r=Atg
+BInt(Ctg+Dtg+E+0.5)+F, but the second term in this equation is a term that converts () into an integer, and unless the physical constant changes to the extent that the integer value shifts due to integer conversion, , there should be no variation in the integer value n at a predetermined point. Therefore, for example P2
．． If you know (tg, tp) at the three points P3゜P4, then Ctg''+D for the known n'', , n'', n''
tg"+ E = n "Ctg"+ D tg"+
E = n p3Ctg”+ D tg”+ E =
n'', it becomes possible to obtain C, D, and E.

Similarly, regarding r, the known n p2 n p3
1111', tp2. r ps, A tg”+ B n ”+ F = r ”A for r94
tg”+ B n ”+ F = r p3A tg”
+ B n From “10F = r”, A.

B.

It becomes possible to obtain F.

Needless to say, when carrying out this embodiment, care must be taken to ensure that each calibration instruction point corresponds accurately to r and n. Therefore, the location of the calibration indication point is
It is necessary to set it at a location shifted from the vicinity where a step occurs in the relationship of phase arrival time tg vs. r as shown in the figure. Note that a step in the phase arrival time tg occurs approximately every λ ν g ν g −ν p .

As an example, λ=3mm, v, =2350m/s
, tl, = 1350m/s, approximately 7mm
Since a step in the phase arrival time tg will occur at each step, points are set by carefully removing the vicinity of this step.

The flow of the system for realizing the above operation is shown in the flowchart of FIG. 2. First, the system is placed in a calibration mode by some switch operation. Then step S
Input 3 points in step S2. Calculate calculation parameters in S3, and switch constants in step S4.
Note that the constants may be changed by rewriting them in a backed-up RAM or by changing the settings of a dip switch or the like that can be read by the microcomputer by some means.

Second embodiment> Next, a second embodiment of the present invention will be described.

In the r calculation formula, A, B, and F provide absolute precision if the Intn number is correct.

By the way, A, B, and F are parameters related to the phase velocity υ and frequency f, and these are related to r and phase arrival time t.
Generally, when the phase arrival time tg is determined by phase zero cross detection, the relationship between r and phase arrival time tg has good linearity for each step, as shown in Figure 3. The slope υ of is also almost the same. Furthermore, T (=1/f), which indicates the break between each staircase, is almost uniform throughout. Therefore, even if these A, B, and F are determined by the method described in the first embodiment, values that are generally close to the true values are obtained and there is no problem in practical use.

However, C, D, and E in the Int function are the group velocity υ,
Since the relationship between r and group arrival time tg is generally observed as shown in FIG. 3, by taking several of these points as in the first embodiment, C
, D, and E is very dangerous. In other words, when the relationship between r and group arrival time tg is obtained as shown in FIG. 3, it is completely meaningless to determine υ from two points as shown in the figure, for example. Therefore, generally C, D
, E, it is necessary to perform some statistical processing in addition to the above method.

Therefore, in this embodiment, the following measures are taken. First, draw an arbitrary curve as shown in Figure 4 with an input pen at an arbitrary location on the propagator at an appropriate speed (tg, t9
) continuously. Then, (tg
, tp) versus r is obtained. On the other hand, the initial value n of the integer value at the starting point A is determined appropriately (for example, O).
, if a step of phase arrival time tg occurs in the direction in which the pen moves away from the sensor, then +1 is added, and -1 is added in the direction in which the pen approaches the sensor, and an integer value n is assigned to each step. As a result, a data group as shown in FIG. 6 is created. Based on this, the independent variables are set as group arrival time tg1 phase arrival time t9. n = = ctg + Dtg where the dependent variable is n
t) Perform multiple regression using the relational expression, and calculate the optimal constants C1D, E
Determine statistically.

Third Embodiment> As a so-called reverse application of the embodiments described above, detection of a displacement amount of a sensor position can be cited. Said 1st. In the second embodiment, (tg, tt
) is a constant for distance calculation, υg+ e+
The method was to calculate f backwards and calibrate using means such as RAM υ backup or dip switches. However, υg. , f is the variation in the thickness of the propagator.

υ It is highly dependent on the influence of the frequency characteristics of the ultrasonic emitting pen, and once the settings are made for each individual product, it is considered to be stable thereafter.On the other hand, it is the sensor position that is likely to change over time due to use. It is.

This is especially true when the product itself is not in a static, stable environment and is subject to frequent shocks. Therefore, υg, υ2, which are initialized based on (tg, tp) when an appropriate position is specified. By back calculating the sensor position using f and feeding back the result to the distance calculation formula, it is possible to correct the deviation of the sensor position.

This will be explained below using FIG. First, when the operating mode of the system is set to the calibration mode by some switch operation, the process proceeds from step S75 to step S76, where points P, , Pl on the absolute coordinate X axis are pointed. At that time, the distance between Pl and sensor S2 + between P2 and sensor S2 was captured in υ step S77 using υM*l+f that was initialized in advance (tg11k, tg9
1).

Step S based on (t, p2, t, pl)
78, and based on the result, the X component of the absolute coordinates of the sensor S2 is calculated. Similarly, Pa and P on the absolute coordinate y-axis
? Point at the point and at that time (tgPat pPa),
The y component of the absolute coordinate of sensor S2 is calculated based on (t, P?, t pP?). In this way, the absolute coordinates of all the sensors are determined, the amount of deviation from the original position is read, and in step S79 this result is fed back to the coordinate calculation formula in the normal operation mode.

In the normal mode, after calculating the distance between the pen and the sensor in step S72 and calculating the indicated coordinates in step S73, step S
In step S74, correction is performed using the sensor deviation correction amount set in step S79.

[Effect of the invention] Various physical constants of the individual products according to the invention.

It is possible to provide an ultrasonic distance measuring device that accurately measures distance regardless of subtle fluctuations caused by adjustment conditions and the like.

In other words, a system configuration is adopted in which the coefficient constant can be newly set and calibrated based on the group arrival time tg9 phase arrival time 1p observed at a predetermined appropriate position or arbitrary consecutive multiple positions. This makes it possible to individually set and calibrate optimal calculation constants for each product, and to eliminate fluctuations in optimal calculation constants due to variations in the physical constants of each component of the product, variations in installation conditions, and changes over time at the factory. Not only at the time of shipment, but also as a service person.

By calibrating on the market, users will be able to easily absorb the data, and applications of ultrasonic distance measurement that ensure stable accuracy will be put into practical use.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the configuration of the pointing point for calibration and the ultrasonic coordinate input device of this embodiment, Fig. 2 is a flowchart showing the processing procedure in the first embodiment, and Fig. 3 is the distance r and group arrival time tg. FIG. 4 is a diagram showing an example of calibration input in the second embodiment. FIG. 5 is a diagram showing the relationship between the date number and the group arrival time tg1 phase in the second embodiment. FIG. 6 is a diagram showing a calibration data group in the second embodiment. FIG. 7 is a flowchart showing the processing procedure in the third embodiment. Schematic diagram, Figure 9 shows the drive voltage of the pointing pen, Figure 1O shows the sensor output waveform, Figure 11 shows an example of the configuration of the signal processing circuit, and Figure 12 explains distance calculation. This is a diagram. In the figure, 1...coordinate indicator, 2.2a to 2C...sensor, 3...propagator, 4...vibration isolating material, 5...first stage amplifier, 6...full wave rectifier , 7...Low pass filter, 8...Differential circuit, 9...Comparator, 10...
- Pen control unit, 20...Sensor control unit, 100...
CPU, 101...ROM, 102...RAM, 1
03... Output section. 9 Figure 6 C Figure 8 p Figure 7 Figure 9 Figure 10

Claims (5)

[Claims] (1) Ultrasonic distance measurement in which ultrasonic waves with different group velocities and phase velocities are emitted from an oscillation source and then received by an ultrasonic sensor, and the distance between the oscillation source and the sensor is calculated based on the arrival time. What is claimed is: 1. An ultrasonic distance measuring device comprising: a correction means for correcting distance calculation based on operation of a predetermined oscillation source prior to distance calculation. (2) The correction means substitutes the group arrival time t_g and phase arrival time t_p at a predetermined position into a predetermined arithmetic expression, and calculates the group velocity υ_g of the calculation parameter used to calculate the distance between the oscillation source and the sensor. , phase velocity υ_p, and frequency f. (3) The correction means calculates the calculation parameters group velocity υ_g,
The ultrasonic distance measuring device according to claim 1, characterized in that a phase velocity υ_p and a frequency f are determined. (4) The correction means calculates the phase velocity υ_p of the calculation parameter by substituting the group arrival time t_g and phase arrival time t_p at a predetermined appropriate position into a predetermined arithmetic expression, 2. The ultrasonic distance measuring device according to claim 1, wherein the calculation parameter group velocity υ_g is determined by a predetermined statistical calculation using the obtained group arrival time t_g and phase arrival time t_p. (5) The correction means calculates the group velocity υ_g, phase velocity υ_p, which are initialized calculation parameters based on the group arrival time t_g and phase arrival time t_p at a predetermined appropriate position.
Claim 1 characterized in that the mounting position of the sensor is calculated using the frequency f, the amount of deviation from the normal position is calculated, and the correction amount for distance calculation during normal operation is newly set and calibrated. The ultrasonic distance measuring device described.