JPH0785021B2 - Initial equilibrium value setting device for measuring equipment - Google Patents

Description

The present invention relates to an initial equilibrium value setting device in a measuring instrument,
In particular, the present invention relates to a device for setting an initial equilibrium value in the case where it is necessary to strictly measure the initial equilibrium before measurement and to ensure the measurement accuracy, such as a barometer.

[Prior Art] In a measuring instrument, a plurality of output signals from a sensor are arithmetically processed to obtain a required measurement value.

For example, as shown in FIG. 6 and FIG. 7, the measurement principle of a center of gravity sway meter is such that the height between the detector upper plate 101 and the detector lower plate 103 that is horizontally adjusted by the horizontal adjusting screw 102 is uniform. 3 or more load cells 104 in place (in this case, 3
Interposer), each load cell 104 is equipped with a strain gauge bridge, and each bridge circuit (Z1, Z2, Z3)
The output from is processed by an arithmetic circuit to measure the center of gravity of the subject on the detector upper plate 101.

That is, when the load cells 104 are arranged at the positions shown in FIG. 7 and the signals obtained from the bridge circuits are W1, W2, and W3, x-7 on the detection unit upper plate 101 The position P (X, Y) of the center of gravity in the coordinates is given by X = c (W3−W2) / ΣWi Y = {b · W1−a (W2 + W3)} / ΣWi (i; 1,2,3).

As shown in FIG. 8, the basic configuration of the analog operation system of the instruction unit that receives the minute signal from the bridge circuit which is the detection unit, performs amplification and arithmetic processing, and gives the center-of-gravity position output P (X, Y) is shown in FIG. It is something. That is, the bridge circuit Z of the detection unit
Signals from 1, Z2, Z3 are amplified by preamplifiers 105a, 105b, 105c to obtain outputs W1, W2, W3, which are arithmetically processed by adders 106a, 106b, 106c and dividers 107a, 107b, and X, It asks for Y.

By the way, W1, W2, and W3 are signals due to the load applied to each load cell, but when the load is zero, these signals should also be zero. However, since the signal of the bridge circuit generally includes an initial unbalanced signal, in order to obtain an accurate position P (X, Y), it is necessary to strictly establish the initial balance before measurement.

In addition, this initial unbalanced signal drifts with temperature and time as well, so a more accurate measurement may be
Bridges Z1, Z2, Z3 that are signal processing units and detection units such as 105
Drift with temperature and time at must be eliminated.

This work is, of course, the same for the manual type and the one using the auto balance method.

As an example, when handling a body weight range of about 10 to 100 kg with a voltage of 1 to 10 V, the output corresponding to the initial imbalance value is adjusted to 10 mV or less in order to obtain 1% accuracy for the position of the center of gravity. There is a need. With such a low level voltage, drift due to factors such as temperature and time has a great influence, and this must be removed. Further, the divider 107 is extremely expensive to reduce the error. You will have to use various parts.

Therefore, in order to improve the accuracy of the arithmetic portion, a digital one of the analog arithmetic portion, which is digitized by using an A / D converter, a microprocessor or the like, is widely used as shown in FIG.

This calculation part is the analog signal W1, from the preamplifier 108.
W2 and W3 are switched by the multiplexer 109 and input to the A / D converter 111 via the sample and hold (S / H) circuit 110 and sent to the actual calculation unit. This calculation unit is a microprocessor. CPU 112, as memory
A RAM 113 and a ROM 114 are provided, and an I / O controller 117 is provided as an interface for controlling and continuing the operations of the arithmetic unit, the A / D converter 111 and the output side D / A converters 115 and 116. There is. Each unit is connected by a data bus and an address bus or a control line.

By the way, in this digitized arithmetic unit, an I / O controller 117 is provided with an initial equilibrium request switch 118 as a means for achieving a problematic initial equilibrium, and a subject is placed on the detection unit upper plate 101 (FIG. 6). After confirming that you are not riding, turn on the switch 118 and set the initial equilibrium values W1, W2, W3 to RAM11.
3, the CPU 112 is put into the ROM 114, and the CPU 112 is caused to perform an initial equilibrium process for correcting later measurement data using the initial equilibrium value. In this way, if the initial balancing process is performed using the digital method, when the A / D converter is 12 bits,
The accuracy can be improved to about ± 0.1% by setting the measuring range to φ300 mm on the detection unit upper plate 101 (Fig. 6).

[Problems to be Solved by the Invention] However, even in the above-described digital center of gravity perturbation meter,
It was necessary to maintain the stability of the preamplifier at an extremely high level, for example, in a detector with a sensitivity of 1000 με / 100 kgf, at room temperature, that is, in the range of 10 to 30 ° C, the output conversion is 0.1% / 20 ° C, that is, 10 mV To obtain zero-point stability, the gain of the preamplifier becomes 10,000 times with a bridge voltage of 2V to obtain an output of 10V at 100kgf. Therefore, 0.1% for changes of 20 ° C or more
In order to suppress the zero-point stability below, an element that requires a stability of 0.05 μV / ° C or less is required (generally, the one with a stability of about 10 μV / ° C is easily available at a low price). Further, not only the preamplifier but also the stability of the detection section is more important, so that the zero point / temperature compensation is strictly required, and the cost is usually very high.

Moreover, according to the initial balancing process in the digital method,
Although the measurement accuracy is certainly improved, it is similar to the analog type in principle only by digitizing and processing the analog amount, and there are the following problems.

That is, make sure that the subject is not on the detector,
It is necessary to carefully turn on the initial equilibrium request switch 118 before the measurement, which makes the operation very troublesome, and it is also necessary to have a judgment means such as whether or not accurate data is taken as the initial equilibrium value. It's a problem.

In order to improve this problem, it is possible to consider a method of solving it by software using an algorithm as shown in FIG. 10 and FIG.

Figure 10 is a graph in which the vertical axis represents the sum of the outputs of W1 to W3 as ΣZi (i; 1,2,3) and the horizontal axis represents time. The time zone indicated by T1 in the figure is detected by the subject. In the middle of getting on the club, T2 indicates the stage where the subject has completely got on, and T3 indicates the stage where the subject is getting off.

This algorithm sets a threshold value α for determining whether or not the subject is on the detection unit, and sets the previous sampling value ΣZi (t−1) and the threshold value Σ at that time for each sampling.
Zi (t) is compared, and when the relationship of ΣZi (t) −ΣZi (t−1) ≦ α is established, the initial value is newly rewritten to obtain the initial equilibrium value. To do.

However, as shown in FIG. 12, the test subject rides on the detection section with great force, and when the rise of the output is rapid, it is directly rewritten and there is not much error, but when the test subject rides slowly as shown in FIG. The rising edge becomes gentle, and as a result, the initial value is rewritten one after another, and it becomes impossible to distinguish between the initial value and the data to be measured.

In addition, it is difficult to require a subject with some impairment in balance function to perform the same movements and body movements as a healthy person.

Therefore, it is not always possible to always obtain an accurate initial value.

The above problem is not limited to the center of gravity perturbation meter, but also exists in measuring instruments that need to perform initial equilibration processing.

Therefore, the present invention does not require the operation of the initial value equilibrium request switch, and can obtain an accurate initial equilibrium value without performing a strict initial value equilibrium operation, and as a result, enables highly accurate measurement. It was created for the purpose of providing an initial equilibrium value setting device for measuring instruments.

[Means for Solving Problems] The present invention relates to a plurality of sensor output signals (Z1, Z2, ...),
A change (ΔW) per unit time in the sum (W) of the sensor output signals, a threshold value (dw) for evaluating a minute ΔW, and Δ
Storage means for storing a threshold value (α) for evaluating whether or not W is a size to be measured, comparison means for comparing ΔW and dw and α stored in the storage means, and ΔW in the comparison means The result of comparison with α is ΔW ≦ α
When (or ΔW <α), an initial value correction unit that rewrites or holds the initial value of the sensor output signal in the storage unit based on the comparison result of ΔW and dw, and a comparison between ΔW and α in the comparison unit The result is ΔW> α
The present invention relates to an initial equilibrium value setting device in a measuring instrument, which comprises an initial equilibrium value reading means for reading the initial value stored in the storage means as an initial equilibrium value when (or ΔW ≧ α).

[Operation] The basic configuration of the present invention is shown in FIG.

The signal input to the device of the present invention is essentially a signal (W) which is the sum of a plurality of sensor output signals (Z1, Z2, ...) And their sum.
Is a signal relating to a change (ΔW) within a predetermined time.

In the figure, reference numeral 1 denotes a storage means which stores the input signal and two evaluation threshold values dw and α.

Then, among the stored data, ΔW, dw and α are read by the comparing means 2a and 2b, and ΔW and dw are read by the comparing means 2a.
However, the comparison means 2b compares ΔW with α.

The comparison result of the comparison means 2b is ΔW ≦ α (or ΔW <
In the case of α), the initial value correction means 3 is activated, an instruction is given to the storage means 1 according to the comparison result of ΔW and dw by the comparison means 2a, and the initial value in the storage means 1 is rewritten or held sequentially. Will be done.

That is, while the condition of ΔW ≦ dw (or ΔW <dw) is maintained, the initial value correction means 3 newly inputs Z ₀ 1, Z ₀ 2 ... Stored in the storage means 1. .. are sequentially rewritten to store newer and more appropriate initial equilibrium values in the storage means 1 at that time.

On the other hand, when ΔW> dw (or ΔW ≧ dw) due to a small signal from the sensor unit due to some cause, it is a problem whether or not the initial value should be rewritten. Because, when the condition is temporarily satisfied, if Z1, Z2, ... at that point is used as the initial equilibrium value for measurement, an accurate measurement value cannot be obtained. Because.

In this case, the new initial value is rewritten only when the state continues for a certain period of time, and the appropriate initial value is always stored in the storage means 1.

In this way, when ΔW ≦ α (or ΔW <α) is established, more appropriate initial values are sequentially stored in the storage means 1, but ΔW> α (or Δ in the comparison means 2b.
When the condition of W ≧ α) is satisfied, it is considered that the measurement stage is entered, and the comparison unit 2b sends the instruction signal 5 to the initial equilibrium value reading unit 4, whereby the initial equilibrium value reading unit 4 is stored at that time. The initial value stored therein is read as the initial equilibrium value 6, and this is output to the predetermined measuring means 7.

At this stage, the operation of the initial value correction means 3 may be stopped by the signal from the comparison means 2b so that the initial value stored in the storage means 1 cannot be rewritten.

As a result, it is possible to obtain an appropriate initial equilibrium value without performing a complicated procedure such as turning on the initial equilibrium request switch or strict initial value equilibration operation in the measuring means, and the measuring means can always perform highly accurate measurement. It will be possible.

By the way, as a concrete means of the initial value correction means 3, the storage means 1 is provided by switching or holding flags.
It is possible to adopt a method of controlling

The relationship between the flag in the initial value correction means 3, the comparison result of the comparison means 2a and 2b, and the initial value to be stored in the storage means 1 may be configured as shown in Table 1.

First, the flag is set when ΔW ≧ dw, and when α ≧ ΔW and ΔW <dw and the flag is in the reset state, the initial value in the buffer is rewritten and stored (1a). , ΔW ≧ dw and the flag is set, leave the flag as it is (1b),
When ΔW ≧ dw and the flag is in the reset state (1c), or when ΔW <dw and the flag is in the set state (1d), the flag is switched to hold the previous initial value.

With this configuration, α is stored in the storage unit 3.
When ≧ ΔW holds, even if the input signal (W) changes, a new and appropriate initial value is always stored by switching or holding the flag, and ΔW>
The initial value can be read out immediately when α is reached and used as the initial equilibrium value for measurement.

[Embodiment] An initial equilibrium value setting device for a body sway meter will be described below as an embodiment of the present invention with reference to FIGS. 2 to 5.

FIG. 2 is a system circuit diagram of the center-of-gravity sway meter. The analog signals from the three bridge circuits (not shown) attached to the load cell of the detector are first preamplifiers 10a, 10b, 10c.
Are amplified by the S / H circuit 12 and the A / D converter 13 while the signals are switched by the multiplexer 11 as W1, W2 and W3.
After that, it is converted into a digital signal and processed.

Each part of the digital signal processing circuit plays the following roles.

By the program of the ROM15, the CPU 14 controls the S / H circuit 12, which is an I / O device, the A / D converter 13, the D / A converters 16a to 16e, and the R.
Read / write to AM17 and ROM15.

The reset circuit 18 sets the CPU 14 to the reset state when the switch 19 is set to a state other than [RUN], and causes the monitor meter 20 to monitor the outputs W1 to W3 of the respective preamplifiers 10a to 10c.
N] releases the reset state of the CPU 14 and starts normal operation.

The clock generation circuit 21 generates a predetermined clock (for example, 2 MHz) and uses it as a system clock.

The CTC22 is a 4-channel counter / timer that divides the system clock and issues a timer interrupt to the CPU 14 at approximately 30 Hz and 1 Hz.

The data to be updated (the initial value at that point and the sum of the initial values, etc.) is written in the RAM17, and the ROM15 is programmed or fixed data (the processing program below, a threshold value for evaluating a minute change in the signal: dw And a threshold value (α, etc.) for evaluating the change in the signal indicating whether or not to start the measurement are written.

The address decoder 23 decodes the I / O device address.

And CPU14, RAM17, ROM15, address decoder 23,
The I / O port is connected to the data bus 24, the address bus 25, and the control line 26. Data from each device appears on the data bus 24 under the control of the CPU 14, and data is exchanged.

The outputs X and Y are analog outputs corresponding to the position of the center of gravity on the detection unit upper plate of the center of gravity sway meter, and the output U is ΣZi (t).
−ΣZoi (t), which is an analog output corresponding to the weight of the subject. Here, the weight of the subject is W (t) = ΣZi
(T), and ΣZoi (t) is an initial value when weight is not applied.

Mx and My are analog outputs corresponding to the moments about the X and Y axes.

Next, the signal processing program for setting the initial equilibrium value in this embodiment is shown in FIGS. 3 and 4, and its operation will be described by taking the case where W (t) changes as shown in FIG. 5 as an example. To do.

First, the main routine (FIG. 3) initializes the system, sets the operating conditions of the I / O device, and prepares for interrupt processing. Here, step 5
[Capture data] is to obtain initial values Zo1, Zo2, Zo3 and store them in the buffer memory, respectively.
1) It is a flag that is set when | ≧ dw,
[Enable interrupt for a certain period of time] in step 9 is CH3 of CTC.
The initial value is processed by interrupting for about 3 seconds only (it takes about every 1Hz), and the [CTCCH
The interrupt enable of 2] is for calculating the position of the center of gravity (X, Y), etc. (takes about every 30 Hz).

In this case, as a specific restriction on the system, the main routine is executed after the power is turned on, and the CPU1 shown in FIG.
It is necessary to apply no force to the detection unit until 4 becomes the halt state (about 5 seconds), and switch 19
Is set to a value other than [RUN] and the output of each preamplifier 10a-10c is monitored by the monitor meter 20 (during this time, the CPU 14 is in the reset state). For example, the output of the preamplifier 10a-10c is within ± 1 scale from the center of the monitor meter. It is necessary to operate the equilibrium adjusting unit so that it can be entered, but the operation in this case does not need to be strict as in the conventional case.

Thus, when the power is turned on, as for the time until the CPU 14 halts (about 5 seconds), the initial value of the problem is Z (0) → Z (1) → Z (2) as shown in FIG. → It can be rewritten as follows. This operation is | ΣN in relation to the minute change dw of the signal (in this embodiment, the value corresponds to 1 kg).
When the condition that EWZi-ΣOLDZi | ≦ dw is satisfied, the previous sampling value (OLDZi) is calculated as the initial value Zoi (t).
Based on the processing.

Next, looking at the interrupt routine of FIG. 4, this routine determines whether or not to rewrite and hold the initial value and start measurement.
Is Z respectively when Z1, Z2, Z3 at that time is input
It is to store in the buffer 1, Z2, Z3,
[25] [| ΣNEWZi-WO | ≧ 8kg?]
8 kg is used as the evaluation value of whether or not the subject is on the detection unit upper plate, and the sum of the initial values held at that time WO = Σ
Zoi and ΣNEWZi are compared with each other, and measurement is started when the comparison formula is satisfied.

Here, the operation in the state shown in FIG. 5 (this state occurs when the detection unit is erroneously touched or when the detection unit is ridden on) is examined.

First, since | W (8) -W (7) | ≧ dw, step 26
The flag ZCHGFLAG is set by → 31 → 32, but the initial value is not rewritten only by switching the flag, and at t = 8, Zo (8) = Z (6) remains.

Next, at t = 9, | W (9) −W (8) | <dw, so the flags are reset by steps 27 → 28. No rewriting is done.

When t = 10, | W (10) −W (9) | <dw and the flag is in the reset state, so the initial value is rewritten from Z (6) to Z (9) by steps 27 → 33. To be

Similarly, desirable initial values are stored until t = 14. (In this case, Z (13) is stored at t = 14.) Transient data such as Z (9) may be temporarily stored in the middle, but it is practical. There is no problem on the top. This is because, as will be described later, unless a load of 8 kg or more, which is a threshold value, is detected, the measurement state is not entered, and naturally, the restriction that the position is not detected is easily permitted.

Next, consider the state shown by in FIG.
This state represents a transitional state from when the subject actually tried to get on the detector to when he / she completely got on the detector.
That is, it is in a state of being ready for measurement.

Here, the output W (t) from the detector rapidly increases to reach a value close to the weight of the subject, and rises and falls in the vicinity thereof. Normally, in the equilibrium function test caused by Parkinson's disease or the like, this assumption is almost satisfied because it is performed in a stationary state in three dimensions, and it does not go up and down violently.

By the way, as shown in step 25 in the flow of the signal processing program of FIG. 4, when | ΣNEWZi-WO | ≧ 8 kg is satisfied, the measurement is performed at once and the initial value data is not changed at all and only the reading is performed. Do.

Therefore, the initial value data Zo (t) between 5 = 15 and T + 3 (measurement during this period) remains Z (13).

In the vicinity of t = T + 1 and T + 2, the state in which the subject descends from the detector detector appears. Although it is determined that the measurement state is exited at t = T + 2, since ZCHGFLAG is set at T = 15 in this example, the initial value data remains Z (13) until t = T + 4.

After that, Zo (t) is updated as Z (T + 4) → Z (T + 5) as in the sequence before the state shown by the above.

In some cases, ZCHGFLAG may not be set and the states may be changed all at once, but there is little difference in operation.

As a result of the above, the initial equilibrium value setting device for the body sway monitor in the present embodiment always stores a newer and more appropriate initial equilibrium value at the time of starting measurement, without performing the operation of the balance adjusting section very strictly. Since the data is automatically read, it is possible to improve the measurement accuracy of the position of the center of gravity, regardless of how the subject rides on the detection unit.

Further, according to the apparatus of this embodiment, even if the preamplifier or the like is not highly stable and the zero point / temperature compensation of the detector is not performed, it is as high as or higher than the conventional one. The position accuracy could be obtained.

[Advantages of the Invention] As described above, according to the present invention, a plurality of sensor output signals (Z1, Z
Change of signal (W) which is the sum of 2, ...
W) is provided with two kinds of threshold values (α and dw),
Since a new and appropriate initial value is stored and used at the stage of starting measurement, a desirable initial equilibrium value can always be used, and highly accurate measurement is possible.

Also, in the measuring instrument, it is not necessary to use a highly stable preamplifier, the zero point / temperature compensation of the sensor part is not required, and it is not necessary to adopt a more expensive and costly automatic balance adjustment method (simple Potential potentiometer is sufficient) and cost reduction can be realized.

From the point of view of the operation of the measuring instrument, there are various advantages that it is not necessary to strictly adjust the zero point, there is no need to monitor the zero point during the measurement, and it is possible to concentrate on the measurement including instruction of the subject. .

[Brief description of drawings]

FIG. 1 is a block diagram showing a basic configuration of the present invention, FIG. 2 is a system circuit diagram of a center of gravity swayometer as an embodiment, FIG. 3 is a flow chart showing a main routine of a signal processing program, and FIG. 4 is a signal. FIG. 5 is a flow chart showing the interrupt routine of the processing program. In FIG. 5, the horizontal axis represents time, and the vertical axis represents the sum W (t) of Zi (t) (i = 1,2,3) corresponding to each bridge circuit output. A graph showing the change of W (t) with respect to time (Z that represents the change of the initial value Zoi (t) at the bottom
(T) is associated. ), FIG. 6 is a side view of the detecting portion of the body swayometer, FIG. 7 is a plan view of the same, FIG. 8 is a system circuit diagram of an analog swayometer, and FIG. 9 is a digital swayometer. System circuit diagram, Figures 10 to 12 show time on the horizontal axis and Zi corresponding to each bridge circuit output on the vertical axis.
(T) (i = 1,2,3) sum ΣZi, and ΣZ with respect to time
It is a graph which shows change of i. 1 ... storage means, 2a, 2b ... comparison means 3 ... initial value correction means 4 ... initial equilibrium value read means 5 ... instruction signal, 6 ... initial equilibrium value 7 ... measurement means

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location G01M 1/12

Claims (3)

[Claims] 1. A plurality of sensor output signals (Z1, Z2, ...
.), A change (ΔW) per unit time in the sum (W) of the sensor output signals, a threshold value (dw) for evaluating a minute ΔW, and a threshold value (a threshold value for evaluating whether or not ΔW is a value to be measured. α), a comparing means for comparing ΔW and dw and α stored in the storing means, and a comparison result of ΔW and α in the comparing means is ΔW ≦ α
When (or ΔW <α), an initial value correction unit that rewrites or holds the initial value of the sensor output signal in the storage unit based on the comparison result of ΔW and dw, and a comparison between ΔW and α in the comparison unit The result is ΔW> α
An initial equilibrium value setting device in a measuring instrument, comprising an initial equilibrium value reading means for reading the initial value stored in the storage means as an initial equilibrium value when (or ΔW ≧ α). 2. The initial value correction means gives an instruction to the storage means by switching or holding a flag to rewrite or hold the initial value.
An initial equilibrium value setting device in the measuring instrument according to the item. 3. The flag is set when ΔW ≧ dw, and when ΔW <dw and the flag is in the reset state, the initial value in the storage means is rewritten and stored, and ΔW ≧ dw and When the flag is in the set state, the flag is left as it is, and when ΔW ≧ dw and the flag is in the reset state, or when ΔW <dw and the flag is in the set state, the flag is switched to the previous initial value in the storage means. The initial equilibrium value setting device in a measuring instrument according to claim (2), which holds a value.