JPH0450533B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to an apparatus for detecting acceleration using velocity detection data.

Prior Art Conventionally known accelerometers utilize the inertia of a liquid to obtain angular acceleration in an analog manner, and have limits in detection resolution and detection range. In order to overcome these drawbacks, Japanese Patent Application Laid-Open No. 57-70465 proposes an acceleration detection device using phase shift type (phase modulation type) rotational position detection, that is, a rotational accelerometer. An acceleration detection device using such a phase shift type position detector has the advantage of being able to detect acceleration with high resolution and over a very wide area. However, in the method disclosed in the above publication, the speed is determined by calculating the frequency or period difference between the output signal of the phase shift type position detection sensor and the reference AC signal, and the speed thus determined is calculated. The rotational acceleration is simply detected by calculating the change per unit time using an arithmetic circuit.
It was not possible to freely switch the acceleration detection resolution.

In Utility Model Application No. 53-134880, a speed generator is used to generate an incremental pulse train with a frequency corresponding to the speed, and speed data is obtained by counting the number of pulses of this incremental pulse train at every fixed sampling period T. By sequentially storing this speed data at each sampling period T and performing predetermined calculations based on this stored data, it is possible to perform speed detection and acceleration detection by variably adjusting the correlation between responsiveness and resolution. It is shown. For example, if the speed data counted in the sampling period T is output as is, it is possible to obtain speed detection data that has the responsiveness of the time T and has a resolution corresponding to the minimum possible count value for the time T. By calculating the difference in detection data per time T, acceleration detection data with corresponding responsiveness and resolution can be obtained. In addition, if the sum of speed data counted in two periods of the sampling period T is output as speed detection data, the response time is
2T, and the resolution corresponds to the minimum possible count value for a time of 2T. By finding the difference in this velocity detection data per time 2T, it is possible to obtain acceleration detection data with corresponding responsiveness and resolution.

Problems to be Solved by the Invention In the prior art described above, it is possible to perform speed detection and acceleration detection by variably adjusting the correlation between responsiveness and resolution, but in that case, the relationship between responsiveness and resolution is It was inversely proportional, making it impossible to variably control the resolution while maintaining the desired high response. Furthermore, since the system counts incremental pulse trains, the maximum response depends on the pulse generation interval, that is, the speed, and it has been impossible to achieve high responsiveness that is independent of the speed. Furthermore, the resolution also depends on the number of pulses generated per time, that is, the speed, and resolution control that is independent of the speed is not possible.

This invention was made in view of the above points,
It is an object of the present invention to provide an acceleration detection device that achieves high responsiveness and can also variably set detection resolution.

Means for Solving the Problems An acceleration detection device according to the present invention includes a sensor section that generates an output AC signal obtained by shifting a reference AC signal in phase according to the position of a detection target, and an output AC signal of the sensor section and the reference AC signal. a position calculation means for calculating a phase difference of a signal at a sampling timing periodic to the period of the output AC signal and outputting it as position data of the detection target; and a change amount of the position data at each time interval synchronized with the sampling timing. speed calculation means for calculating and outputting as speed data of the detection target; storage means for successively capturing and storing the speed data obtained by the speed calculation means at time intervals synchronized with the sampling timing; Using the speed data stored in the means, calculate the difference between the speed data taken in at a certain point and the speed data taken in N times before (N is an integer), and output it as acceleration data. and an acceleration calculation means, by variably setting the value of N or by variably dividing the period of the sampling timing, variably setting the acquisition time difference between the two velocity data used by the acceleration calculation means, whereby the acceleration data and setting means for variably setting the resolution of.

Operation The sensor section is comprised of a phase type sensor that generates an output AC signal that is a reference AC signal phase-shifted according to the position of the detection target. The phase difference between the output AC signal of the sensor section and the reference AC signal corresponds to the position of the detection target, and the phase difference is 1.
It can be measured every cycle. Therefore, the position calculation means calculates the phase difference between the output AC signal of the sensor section and the reference AC signal at a sampling timing synchronized with the cycle of the output AC signal, and outputs this as position data of the detection target. . This sampling timing, or responsiveness, primarily depends on the electrical period of the alternating current signal, and does not depend on the speed of the detection target at all. For example, if the frequency of the AC signal is
At 1kHz, it has a response of 0.001 seconds, which is completely independent of the speed of the detection target.

The speed calculating means calculates the amount of change in the position data at each time interval periodic to the sampling timing, and outputs it as speed data of the detection target. Since this speed calculation is also performed at time intervals synchronized with the sampling timing, the responsiveness of speed detection also does not depend on the speed of the object to be detected at all, but primarily depends on the electrical period of the AC signal.

The speed data obtained by the speed calculation means is successively taken into the storage means at time intervals synchronized with the sampling timing and stored. The acceleration calculation means uses the speed data stored in the storage means to calculate the difference between the speed data taken in at a certain point and the speed data taken in N times before (N is an integer). , output as acceleration data. This acceleration calculation can also be performed every acquisition cycle, so it can be performed at time intervals synchronized with the sampling timing, and therefore the responsiveness of acceleration detection does not depend on the speed of the detection target at all. First, it depends primarily on the electrical period of the AC signal.

In this way, it is possible to detect acceleration that is not dependent on the speed of the object to be detected but is uniquely dependent on the electrical period of the AC signal. The responsivity depending on the period of the electrical alternating signal is quite high.

Also, unlike those that count incremental pulses according to the mechanical movement of the detection target,
Since the electrical phase difference is measured, the detection resolution does not depend on the speed of the detection target at all.

Variable setting of resolution can be performed by a setting means. The setting means variably sets the acquisition time difference between the two velocity data used by the acceleration calculation means by variably setting the value of N or variably dividing the period of the sampling timing. Thereby, for example, the resolution can be increased as the capture time difference becomes larger, and the resolution can be lowered as the capture time difference becomes smaller, thus making it possible to variably set the resolution of acceleration data. Therefore, efficient acceleration detection can be performed by setting an appropriate resolution according to the application.

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

In FIG. 1, a speed detection device 10 outputs speed data D _V indicating the current speed of the detection object in response to rotational motion or linear motion of the detection object. In other words, when the speed of the detection target changes over time, the value of this speed data _DV changes moment by moment according to the rate of this change, that is, the acceleration. The output data D _V of the speed detection device 10 is applied to the first stage of an N-stage shift register 11 which can store all bits of one speed data D _V per stage. The shift register 11 is shift-controlled by a sampling pulse S. When the sampling pulse S is generated, the current speed data from the speed detection device 10 is sampled at the first stage of the shift register 11, and at the same time, the speed data at each stage is shifted to the next stage. In this way, the speed data _DV determined by the speed detection device 10 is sampled one after another as time passes, and the sampled data are stored in the shift register 11 one after another.

The output data D _V of the speed detection device 10 is transmitted to the arithmetic unit 1.
2 and is applied to the B input of shift register 11.
The output D _VN of the stage is given to the A input of the arithmetic unit 12. The arithmetic unit 12 performs subtraction A-B, that is, D _VN - D _V (on the contrary, it may be B-A), and calculates the speed data D _V at the current sampling timing and the speed sampled N times before. Find the difference between data D and _VN . Note that the speed data given to the B input of the arithmetic unit 12 may be an output signal of any stage of the shift register 11; in short, it is sufficient that the sampling timings of the position data applied to the A input and B input are shifted by a predetermined number of times. .

The difference ΔD _V between the speed data outputted from the calculator 12 in this way represents the amount of change in speed of the detection target per unit time corresponding to N periods of the sampling pulse S, and corresponds to the acceleration of the detection target. .

By the way, if the unit time for measuring the difference △D _V (that is, acceleration) is fixed as shown in Figure 1,
It is difficult to perform efficient acceleration detection over a wide range of speeds. For example, if the unit time (value of N) is set to a value suitable for high acceleration detection, the difference ΔD _V with sufficient significant digits cannot be obtained in the low acceleration range. On the other hand, if the above unit time (value of N) is set to a value suitable for low acceleration detection, a difference △D _V with an unnecessary large number of significant digits will be obtained in the high acceleration region, and the calculation will be difficult due to this. Therefore, the number of bits in the circuit 12 must be increased unnecessarily. Generally, in acceleration detection,
It is not necessary to have the same detection resolution in the high acceleration region and low acceleration region; it is more efficient to ignore the lower digits as the acceleration increases, so that acceleration can be detected with the same number of significant digits in any acceleration region. It is true.

In view of the above points, FIG. 2 shows an example in which the value of the sampling frequency difference N between the speed data _DV and _DVN calculated by the calculator 12 is variably set. In FIG. 1, N is treated as a fixed integer, but in FIG. 2, N is a variable integer.
The number of stages M of the shift register 11 is a fixed integer, and the maximum settable value of N is M. The successively sampled speed data stored in each stage of the shift register 11 is input to the data selector 13, respectively. The N setting circuit 14 is for variably setting the value of N, and data indicating the value of N set by this circuit 14 is applied to the selection control input of the selector 13, and the shift register 11 corresponding to this value of N is applied. One stage is selected, and the speed data stored in that stage is set as D _VN and A
give to input. In FIG. 2, the output data D _V of the speed detection device 10 is given to the B input of the arithmetic unit 12, but the output data of the first stage of the shift register 11 may be given instead.

The N setting circuit 14 is given the difference data △D _V (that is, acceleration data) obtained by the calculator 12, and is configured to automatically set the value of N according to the acceleration (acceleration region) of the detection target. It's getting old. Of course, it goes without saying that the value of N may also be changed manually. N setting circuit 1
4, as shown in FIG. 3, includes an N table 15 and a buffer register 16 that temporarily stores the N value data read from the table 15, and the difference data △ given from the arithmetic unit 12.
Table 1 uses D _V (acceleration data) and N value data given from buffer 16 as address input.
Read the N value data from 5. The N-value data weights the difference data ΔD _V , and the actual acceleration is set by both. In the N table 15, N values are stored in advance in correspondence with a plurality of acceleration regions, and N value data corresponding to the acceleration is read out by a combination of the difference data ΔD _V and the current N value data. The value of N is set so that it is inversely proportional to the acceleration. For example, when the current acceleration belongs to the lowest acceleration area of the setting, the shift register 11
The output of the last stage (M-th stage) is selected, and as the acceleration region gradually increases, outputs are sequentially selected from the previous stage.

FIG. 4 shows another example of the N setting circuit 14, in which a comparator 17 compares a predetermined upper limit reference value R _nax , a predetermined lower limit reference value R _nio and difference data ΔD _V from the arithmetic unit 12. Depending on the output of this comparator 17,
A down counter 18 performs counting, and the count output of this counter 18 is used as N value data.
The output data △D _V of the arithmetic unit 12 is R _nio ≦△D _V ≦
The contents of the counter 18 do not change within the range of R _nax ,
The N value data at that time is held. When the acceleration increases and ΔD _V >R _nax , a down count signal is given to the counter 18, and the value of N is decreased by 1. On the other hand, when ΔD _V <R _nio , an up count signal is given to the counter 18 and the value of N is incremented by one.

In the example of FIG. 2, the output data △D _V of the arithmetic unit 12 indicates the effective digits of the detected acceleration,
Data indicating the value of N currently set by the N setting circuit 14 (N value data) indicates the weight of the significant digit data ΔD _V of the acceleration. Therefore, data △
The absolute value of acceleration is specified using _DV and N value data.

In addition, in the example of FIG. 2, the sampling pulse S
The calculation unit time of the speed data difference △D _V is changed by changing the difference (N) in the number of sampling times without changing the cycle of the sampling pulse S. The period may be changed according to the output of the N setting circuit 14, or both the difference in sampling times (N) and the period of the sampling pulse S may be changed.

As the speed detection device 10, Japanese Patent Application Laid-Open No. 57-70460
It is also possible to use a system that uses a phase shift (modulation) type position detection switch as shown in the above publication to obtain velocity data through calculation.

As an example of the speed detection device 10, FIGS.
Examples in which speed detection is performed using the same concept as shown in the figure are shown in FIGS. 5 and 6. FIG. 5 shows a speed detection device 10 configured based on the same concept as FIG. 1, and FIG. 6 shows a speed detection device 10 configured based on the same concept as FIG. , arithmetic unit 12', selector 13', N
The setting circuit 14' is connected to 11 and 1 in FIGS. 1 and 2, respectively.
2, 13, and 14. Position detector 30
outputs position data D _X indicating the current position of the detection target in response to rotational displacement or linear displacement of the detection target. When the detection target is displaced over time, the value of this position data D _X changes moment by moment according to the rate of displacement, that is, the speed. Therefore, using the same method as described above, it is possible to obtain velocity data _DV based on position data _DX that changes from moment to moment.

As the position detector 30 shown in FIGS. 5 and 6, a phase shift type absolute position detector is used. Among these, the use of a variable magnetic resistance type phase shift type position detector described below is advantageous in various respects.

The position detector 30 shown in FIG.
The output signal Y=sin(ωt−
θ), and a conversion unit 21 that measures the amount of phase shift θ between this output signal Y and the reference AC signal sinωt to obtain digital position data D _X corresponding to this θ. I'm here. The sensor unit 20 includes a stator 22 in which a plurality of poles A to D are provided at predetermined intervals (90 degrees as an example) in the circumferential direction.
and a rotor (movable iron core) 19 inserted into a stator space surrounded by each pole A to D. The rotor 19 has each pole A to A depending on the rotation angle.
The name refers to the shape that changes the reluctance of D, and an example is an eccentric cylindrical shape. Stator 22
Primary coils 1A to 1D and two pairs of coils 2A to 2D are wound around each pole A to D, respectively. Coils are wound around two radially opposed poles A and C so that they operate differentially, and a differential reluctance change occurs. The same goes for the other pair of poles B and D. 1 of one pole pair A, C
The next coils 1A and 1C are excited by a sine signal sinωt,
The primary coils 1B and 1D of the other pole pair B and D are excited by the cosine signal. As a result, as the composite output Y of the secondary coils 2A to 2D, the reference signal sinωt
(or cosωt) is phase-shifted by an angle corresponding to the rotation angle θ of the rotor 19, and the signal Y=sin(ωt−
θ) can be obtained. Note that when the rotor 19 is rotating at a certain speed, θ is θ
(t). In other words, θ changes from moment to moment.

In the conversion section 21, a predetermined high-speed clock pulse CP is counted by a counter 23, and based on the output of this counter 23, a sine/cosine generating circuit 24 generates a sine signal sinωt and a cosine signal cosωt, respectively, and these are converted as described above. Primary coil 1
A, 1C, 1B, and 1D respectively. The output signal Y=sin(ωt−θ) of the secondary coils 2A to 2D is given to a zero cross detection circuit 25, and a pulse L is outputted in synchronization with the timing of the electrical phase angle of this signal Y being zero. The output pulse L of this circuit 25 is used as a latch pulse of a latch circuit 26. The latch circuit 26 receives the pulse L from the circuit 25.
The count output of the counter 23 is latched in response to the rising edge of . It is possible to synchronize the period in which the count value of the counter 23 makes one cycle with one cycle of the sine signal sinωt. Then, the latch circuit 26 has the reference AC signal sinωt and the sensor unit output signal Y=sin(ωt
-θ) A count value corresponding to the phase difference θ with respect to the current position is latched, and this is output as position data _DX .

When a phase shift type position detector 10 as shown in FIG. 7 is used, the sampling pulse S used in the shift registers 11, 11' in FIGS. 1, 2, 5, and 6 is as follows. A signal synchronized with the phase difference measurement timing (that is, the timing of the latch pulse L of the latch circuit 26 in FIG. 7) can be used. In other words, the latch pulse L is used as it is as the sampling pulse S, or this pulse L is appropriately frequency-divided and used as the sampling pulse S. Similarly, the variable frequency divider 27 is controlled as shown in FIG. 8 according to the N value data set by the N setting circuit 14 in FIG. may be used as the sampling pulse S.

The sensor section 20 shown in FIG. 7 is not limited to the rotary type, but may be a linear type (for example, a variable magnetic resistance type as shown in Japanese Utility Model Application No. 57-135917).

In the above, the shift registers 11, 11', arithmetic units 12, 12', selectors 13, 13', and N setting circuits 14, 14' are shown to be composed of discrete circuits. It is also possible to configure the parts using a microcomputer.

Effects of the Invention As described above, the present invention provides an excellent effect in that there is no need to provide a dedicated sensor for acceleration detection, and acceleration can be easily detected by simple calculations. Furthermore, since acceleration detection is performed by simple calculation using speed data that has already been stored one after another, high-response positive acceleration detection can be performed without time delay. In particular, the phase difference between the output AC signal of the phase type position sensor and the reference AC signal is calculated at a sampling timing synchronized with the cycle of the output AC signal, this is output as position data, and the speed is calculated based on this position data. and acceleration calculations, so
Since the detection responsiveness primarily depends on the electrical period of the AC signal and is completely independent of the speed of the object to be detected, acceleration can be detected with high responsiveness at any speed. Furthermore, since the detection resolution is not affected by the speed of the detection target, it is possible to increase the resolution. Furthermore, the acceleration detection resolution can be freely set while maintaining high responsiveness.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the basic configuration of acceleration detection in this invention, FIG. 2 is a block diagram showing an embodiment of this invention, and FIGS.
5 and 6 are block diagrams showing an example of the speed detection device shown in FIGS. 1 and 2 using the same concept as the present invention, respectively. Figure 7 is similar to Figures 1 and 2.
An explanatory diagram showing an example in which a rotary phase shift type position detector is used as the position detector in the figure, and FIG. 8 is a circuit that generates the sampling pulses of FIGS. 1, 2, 5, and 6. FIG. 2 is a block diagram showing an example. 10... Speed detection device, 11... Shift register, 12... Arithmetic unit, 13... Data selector,
14...N setting circuit, 30...Phase detector, 20
...Sensor section, 21...Conversion section, 22...Stator, 19...Rotor.

Claims (1)

[Scope of Claims] 1. A sensor unit that generates an output AC signal obtained by shifting the phase of a reference AC signal according to the position of a detection target; a position calculation means that calculates at a sampling timing synchronized with the cycle of and outputs it as position data of the detection target; and a position calculation means that calculates a change in the position data at every time interval synchronized with the sampling timing, A speed calculation means for outputting speed data; a storage means for successively capturing and storing the speed data obtained by the speed calculation means at time intervals synchronized with the sampling timing; and utilizing the speed data stored in the storage means. an acceleration calculation means for calculating the difference between the speed data taken in at a certain time and the speed data taken in at the time N times before (N is an integer), and outputting the difference as acceleration data; Setting means for variably setting the acquisition time difference between two velocity data used by the acceleration calculation means by variably setting a value or variably dividing the period of the sampling timing, thereby variably setting the resolution of the acceleration data. An acceleration detection device comprising: 2. The acceleration detection device according to claim 1, wherein the setting means performs the variable setting according to the detected acceleration of the detection target.