JPS6217675A - Apparatus for ultrasonic measurement of position - Google Patents

Abstract

PURPOSE:To enable the continuous measurement of a position and to attain to enhance measuring accuracy and resolving power, by transmitting a continuous ultrasonic wave with definite frequency to receive the same by three receivers and calculating the three-dimensional position coordinates of a transmitter. CONSTITUTION:A continuous ultrasonic wave with predetermined frequency is transmitted from a transmitter 3 moving from a reference position Z0 to a position Z through an oscillator 1 to be received by three receivers 4-6. Relative distance change measuring circuits 7-9 determine relative distance changes r1-r3 of the transmitter 3 and the receivers 4-6 on the basis of the phase change of receiving signals to supply the same to a position operator 11 which, in turn, operates the relative distance of the position Z on the basis of know relative distances R1-R3 and distance changes r1-r3 to the position Z0 to calculate the three- dimensional coordinates (x, y, z) of the position Z. Because the continuous ultrasonic wave with definite frequency is used, an amplifier with a narrow band can be used and external noise is hardly received and the effect of the variation in a receiving level is reduced by measurement based on phase change while information is continuously obtained even with respect to the movement of the transmitter and the continuous measurement of a position is enabled and measuring accuracy and resolving power are enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a position measuring device that three-dimensionally measures the position of each part of a human body, an object, etc. using ultrasonic waves.

[Conventional technology and problems]

2. Description of the Related Art Position measuring devices using ultrasonic waves have a wide range of applications, for example, as means for measuring the walking trajectory of humans and animals, or the movement and position of various parts such as their heads, hands, and feet. Moreover, in recent years, higher precision and higher resolution have been required.

However, the method currently in use uses pulsed ultrasonic waves to calculate and determine the target position by measuring the propagation delay time between the transducer and the transducer corresponding to the distance.

For this reason, there were the following disadvantages.

(b) Since pulse waves are used, the transducer and amplifier must have broadband characteristics, which can easily be contaminated by external noise, causing measurement errors.

(b) ・Measurement of the delay time of the gust wave had low measurement accuracy because of the large influence of fluctuations in the received waveform and received level.

Since the movement of the transmitter cannot be detected within the repetition period of the C unoyalus wave, the resolution of the movement of the transmitter is poor.
Continuous measurements were not possible.

Therefore, the present invention is capable of transmitting continuous ultrasonic waves of a constant frequency from a transmitter instead of an IE pulse wave.
The present invention aims to provide an ultrasonic position measuring device that enables continuous position measurement and has high measurement accuracy and high resolution.

[Failure to solve the problem]

The present invention uses continuous ultrasonic waves with a constant frequency as a signal transmitted from a transmitter, receives this with three receivers, and determines whether the transmitted or received signals are transmitted or received based on the phase change of each received signal. The three-dimensional position of the transmitter is determined by calculating the relative distance change between the transmitters and calculating the relative distance change.
The above problems were solved and the objective was achieved.

[Operation] Set three-dimensional coordinates in the space to be measured, predetermine the reference point of the transmitter and the positions of three 0', ;:) at any position on these coordinates, and set these coordinate values. Remember.

Further, since the distance between the reference point of the transmitter and each receiver is determined by calculation, each of these distances is also stored as a known I. Next, the transmitter transmits continuous ultrasonic waves at a constant frequency, and the three receivers receive the ultrasonic waves and convert them into electrical signals. The phase of these electrical signals changes according to the movement of the transmitter, so by detecting this amount of phase change, the relative distance change between the transmitter and each receiver can be calculated. The three-dimensional position of the transmitter is determined based on the previously stored coordinates of the reference point of the transmitter and the distance from this reference point to each receiver.

〔Example〕

Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 is a block diagram showing the entire structure of the present invention. (1) is
For example, an oscillator that generates a continuous wave signal with a frequency of 40 kHz is connected to a transmitter (3) located at a three-dimensional position Z via a transmission line (2), and the continuous wave signal is transmitted from the transmitter (3). Sent into the air as ultrasound waves. This ultrasonic wave is transmitted to three receivers (4), each of which is set at an arbitrary position in advance.
(5), (6) and the corresponding relative distance change measuring circuit (7), (s),
(9). Here, it is assumed that the positions and coordinate values of the transmitter (3) and each of the receivers (4), (5), and (6) are set in a relationship as shown in the figure. zo is the receiver (3
) indicates the reference point. The three relative distance change measuring circuits (7), (8), and (9) each measure electrical signals corresponding to the sound waves received by the three receivers using the continuous wave signal of the oscillator (1) as a reference. By detecting the phase change amount of the transmitter (3) and the receiver (4),
Relative distance change amount r1+r2 between (s) and (6)
+r3 is calculated. 00 is the reset circuit,
Reference point Z predetermined by the transmitter (3). When it reaches the top, a reset signal is applied to the relative distance change measuring circuits (7), (8), (9) and the position calculation device U. α■ is the relative distance change measurement circuit (7), (8),
Based on the output r1+r2+r5 of (9), the transmitter (
3) is a position calculation device that calculates the three-dimensional position.

Next, the operation shown in FIG. 1 will be explained.

(a), Set three-dimensional coordinates in the area to be measured, and set the reference point zo of the receiver (3) and the three receivers (4) and (5
), (6) preset position 2. ．． 22,2. The coordinate values of are stored in a memory (not shown) such as a RAM in the position calculation device Ql), and these coordinate values are also stored between the reference point of the transmitter (3) and each receiver. distance R1
- R2 and R3 are also calculated and stored in the memory as known quantities.

(b) A continuous wave signal of a constant frequency sent from the oscillator (1) to the transmission line (2) is transmitted into the air as an ultrasonic wave from the transmitter (3), and is sent to three receivers. Received.

The received ultrasonic waves are converted into electrical signals and sent through lead wires to relative distance change measurement circuits (7), (8), respectively.
Sent to (9).

(C), relative distance change measurement circuit (7), (s),
In (9), the receivers (4), (5), (6)
Since the phase of the electrical signal from the transmitter (3) changes as the transmitter (3) moves, this is detected and the amount of change in relative distance between the transmitter (3) and each receiver r1. Calculate and output r2+r3.

The configuration of these circuits is shown in FIG. 2 and will be described in detail later.

(d), the calculated relative distance change amount ri+r2+r5 is sent to the position calculation device (b). Here, with these people,
Distance R1 between front receivers (4), (5), (6)
, R2r J to obtain an arbitrary three-dimensional position 2 of the transmitter (3).Next, the relative distance change measuring circuit (7) described above in FIG.

(8) and (9) will be explained in detail. Note that since each circuit has the same configuration, only (7) will be explained.

A is an amplifier that amplifies the output signal e1 of the receiver (11) according to the transmitted wave of the transmitter (3). [alpha]] is one N multiplier circuit, which increases the frequency of the output signal e'1 of the amplifier (6) by N times. αhiro is the other N multiplier circuit that multiplies the frequency of the output signal eo from the oscillator (1) by N times.

αG is a 90° phase shift circuit that shifts the phase of the output signal eN of 14 by 90°. (IQ and α→ are multipliers, and one multiplier αQ is a N multiplier circuit α1 and α→
The other multiplier 01 multiplies the output signal "'IN" of the N multiplier circuit 01 and the output signal e'N of the 90° phase shift circuit αυ. αη and 0I is a low-ns filter, multiplier α0 and low-ns filter 0
η constitutes one correlation circuit (within the 1-point line), multiplier 0e and low-zoosfil'! and constitutes the other correlation circuit (inside the lower dotted line).翰 and (c) are waveform shaping circuits that shape the output signal waveforms of the two correlation circuits, and are connected to up-grain counters (a), respectively. The output of this up/down counter (2) is input to a D/A converter, and a relative distance change r due to the movement of the D/A converter and the transmitter (3) is output.

Regarding the operation of the relative distance change measuring circuit (7) in Fig. 2 e
It can be expressed as g=E□casωt(1), and the output signal el, which is inputted with the output signal e of the receiver (4) and amplified by the amplifier (6), is expressed as follows. Here, τ is the propagation speed of the sound wave, and R is the transmitter (3)
and the distance between the receiver (4) and the receiver (4). In order to increase the resolution in equation (2), the frequency is multiplied by N times (
N=an integer greater than or equal to 2), then ω/v=2π/λ (λ: wavelength of the ultrasonic wave), so the output signal ``IN'' becomes .

Output signal e of the continuous wave signal of the oscillator (1). the frequency of N
The output signal eN multiplied by N by the multiplier circuit a4 is eH=E
ocas Nωt (4), and when this output signal is applied to the 90° phase shift circuit αυ, the output signal e'N becomes e3's = EOsfn Nωt (5). (4)
By correlating the output signals expressed by equations and (5) with the output signal of equation (3), and setting one output signal to Ec and the other output signal to E3, the following can be obtained. Equation (6) and (7
) in the equation (eNx e', N] and [e'Nxe/, N] indicate the average. This averaging is performed by the low-gust filters (1'i) and (to) in the two correlation circuits. Here (
Combining equations (6) and (7) yields. This represents a vector that rotates once every time the distance Rλ between the transmitter (3) and the receiver (4) changes.
If R increases, it is a counterclockwise rotation vector, and if R decreases, it is a clockwise rotation vector. Therefore, by detecting the phase change of this vector, the relative distance change amount between the transducer and receiver can be obtained. Actually, as shown in FIG. 2, the output signal Ec of the two correlation circuits is
and E3 are converted into i9 pulses by the waveform shaping circuit (e) and gp and counted by the up/down counter (2), and this count output signal is converted into a D/A converter child analog signal and output. This analog signal output is output from the up/down counter (a) and the first By resetting the position calculation device (11) shown in the figure with the output of the reset circuit α0, the output of the D/A converter is set to the reference point Z. This represents the relative distance change amount r1 between the transmitter (3) and the receiver (4) starting from . Similarly, from the other two relative distance change measurement circuits (8) and (9), the respective relative distance change amounts r2 and r3 starting from the reference point 2° of the transmitter (3) are obtained.

As mentioned above, each relative distance change measurement circuit (7), (8
), (9), by using the N multiplier circuit a→, α◆, the frequency of the electrical signal from each receiver (4), (5), (6) is multiplied by N, and as a result, the relative The measurement resolution of the amount of change in distance is also increased by N times. For example, oscillation frequency of oscillator (1): f = 40kHz, sound speed of air;
When v=340m/s, λ (wavelength) = 8.5 m
/m, so if N=4, the resolution is 1 of λ,
That is, approximately 2 m/m is obtained.

As explained above, the transmitter (3) and the three receivers (4), (5) start from the reference point zo of the transmitter (3).
, (6) relative distance change amount r1. r2. Since r3 has been measured, the method for calculating the three-dimensional position 2 of the transmitter (3) from each of these points [η is shown below. Transmitter (3)
When is at the reference point zo, there are three receivers (4), (
5), the distance up to (6) is a known quantity, R1=lz+zol (9)
R2= 1z2-Zol QOR
5=12. -zol (1+)
It can be calculated as follows. These values are stored in advance in the memory within the position calculation device (11). Next, when the transmitter (3) moves from the reference point Zo to a certain point 2, the subsequent relative distance change amount r1. between the transmitter and each receiver.
r2. Since r3 is expressed as r1=lZ ztl R102 r2 = lz 221 R2α] r3=lZ z, l-R, Q4, the above formula (2), α→, (Substituting the coordinate values for I4) The following equation is obtained.

(x-a)2+ y2+ z2= (R, + r,)2
αυ(x+a)2+y2+z2=(R2+r2)
2aQx2+72+(z-c)2= (R5+rs)2
According to the α force, the above formula (g), (IQ, from a'h, the coordinate value of the three-dimensional position 2 of the transmitter (3) X + y +
Z can be found using the following formula.

A device for calculating the position of the transmitter (3) based on these equations aυ, (to), and 4 is shown as a position calculation device aυ in FIG. This position calculation device (b) can be easily implemented using, for example, a microcomputer, and the transmitter (3) is moved to the reference point Z by a signal from the reset circuit αO.
Knowing that it has come above o, the relative distance change measurement circuit (7)
The three-dimensional position Z of the transmitter is calculated from the output signals "1.r2.r3" of , (8) and (9), and each coordinate value and required value of the transmitter/receiver stored in advance.

In addition, in the above explanation, three receivers are used, and the transmitter (3)
The position of the receiver was determined three-dimensionally, but of course, if there are two receivers, the two-dimensional position (plane position) can be determined, and if there is one receiver, the one-dimensional position (straight line distance) can be determined. .

Also, instead of using the transmission line (2), the continuous wave signal of the oscillator (1) can be transmitted wirelessly to the transmitter (3) using a telemeter system.

〔Effect of the invention〕

As explained above, according to the present invention, the following various remarkable effects can be obtained.

(b) Since the transmitted signal uses a continuous wave signal with a constant frequency instead of a gust wave, a narrow band amplifier can be used, which is less susceptible to external noise and provides a high S7 ratio. It will be done.

(b) Measurement is performed by changing the phase using a continuous wave signal with a constant frequency, so the influence of fluctuations in the reception level is small and highly accurate position measurement is possible.

Information regarding the movement of the H transmitter can be obtained continuously and the resolution is high.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an outline of a preferred embodiment of the present invention, and FIG. 2 is a block diagram showing a detailed configuration of the relative distance change measuring circuit of FIG. 1. (3)...Transmitter, (4)-(6)...Receiver, (
7) to (9)... Relative distance change measurement circuit, 00)...
・Reset circuit, Ill...Position calculation device, +13
1. Circle... N multiplier circuit, (19... 90° phase shift circuit, (221... Up/down counter, 23
)...D/A converter.

Claims (1)

[Claims] An oscillator that generates a continuous wave signal of a constant frequency, a transmitter that transmits this signal as an ultrasonic wave, and three receivers that are preset at arbitrary positions to receive the ultrasonic wave from this transmitter. By measuring the phase change of the electric signal corresponding to the ultrasonic wave received by these three receivers with reference to the continuous wave signal of the oscillator, the amount of change in the relative distance between the transducer can be calculated. a relative distance change measuring means for calculating, a position calculating means for calculating a three-dimensional coordinate position of the transmitter from these relative distance changes; An ultrasonic position measuring device comprising a reset means for resetting the relative distance change measuring means.