JPS6020703B2 - Circuit device for digital measurement of rotational speed of rotating parts - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention includes a detector that generates a signal with a frequency proportional to the rotational speed, and a measuring device that measures the period time of said signal that is inversely proportional to the rotational speed. The present invention relates to a digital measuring device for the rotational speed of a rotating member, for example a wheel, in which the signal period time has a hyperbolic relationship.

It is known to use pulse generators in combination with electrical pulse counting devices to measure the rotational speed of rapidly rotating machines.

The frequency of the pulses is measured by a detector generating one or more pulses per revolution of the shaft, which pulses are counted over a predetermined measuring time in a Cowart device. In this way, a measurement result is obtained that is averaged over a period of time, ie a measurement result that is proportional to the average rotational speed. This method is therefore not suitable for measuring changes in rotational speed during a time segment corresponding to a fraction of a revolution, as is necessary for example in a motor vehicle wheel during braking for skid control purposes. During the braking process of a motor vehicle, such short-term rotational speed changes occur. Measuring the corresponding frequency changes using the above-mentioned known methods is not possible since spatial and measurement technical conditions impose an upper limit on the number of pulses per revolution and require a relatively long measurement time. It is. Therefore, a method has already been proposed in which the period time of pulses generated from a pulse detector is measured by generating and counting high-frequency pulses during that period (in the following explanation, In order to distinguish it from frequency pulses, the pulses generated by the detector are called signals.)

However, in this case it is extremely difficult to read because the period time T is inversely proportional to the rotational speed and therefore also to the speed of the vehicle.

Generally, the relationship T=k·i/ (where k is a constant) holds true. In other words, T and people have a hyperbolic relationship. In order to obtain the frequency as the amount of crosstalk, the reciprocal must be found from the measured value corresponding to the period time.

This reciprocal calculation can be performed, for example, by a computing device. However, the cost of the necessary electronic components is significant. moreover,
A relatively long delay between the generation of the signal and the end of the computational operation,
This increases calculation time and reduces measurement resolution. Now, in order to obtain a linear relationship between the rotational speed and the signal period time for each section, it is possible to approximately simulate the hyperbolic relationship of 1/T of ``■'' using a simpler function.

A method has already been proposed for ``approximately simulating a hyperbolic function using auxiliary frequencies'' by grading the frequency corresponding to an exponential function.

In this case, it is essential to make the frequency of the pulse train variable. The disadvantage of this method is that it requires the use of a large number of frequencies stepped by a factor kX, which makes the electronic components for generating these frequencies relatively expensive. The resulting frequency step requires a relatively long time for the calculation operation, since the curve section in the low speed range has to operate at a very low frequency to obtain its slope. If the length is longer, the dead time from signal generation to obtaining the calculation result, that is, the time during which it is impossible to measure the signal period time, will be increased, which will reduce the resolution.Therefore, an object of the present invention is to avoid the above-mentioned drawbacks. In particular, it is possible to simulate the hyperbolic relationship between speed and period time from the measured signal period time in a short period of time and at a small cost, and also to create a measurable quantity corresponding to speed with sufficient accuracy guaranteed. The purpose is to provide a device that can obtain the following.

To solve this problem, we developed a detector that generates a signal with a frequency proportional to the rotation speed of the rotating member, a measuring device that measures the period of the signal, and a hyperbolic function that shows the relationship between the rotation speed and the detector signal period. ``According to the present invention, a measuring device is provided with a storage device for storing an electrical quantity corresponding to a specific speed division of a specific speed measurement range determined by a given group of approximate straight lines. A comparison and control device is connected to the measuring device, which compares the measured values generated by the device with the above-mentioned electrical quantities; A first shift register is connected, the number and direction of the control signals of this shift register are determined by the output signals of the comparing and controlling device, and an inverting device is connected to the first shift register and the control signals of this shift register are determined by the output signals of the comparing and controlling device. The output signal of the blind eye connects a second controllable shift register via the control conductor, the number and direction of which shift register control signals are likewise determined by the output signal of the comparison and control device, and both shift registers The sum of the control signals corresponds to the slope of the approximate straight line within the speed section.

In order to explain the invention, the underlying principles will be explained in advance.

It is divided by the hyperbola of formula = a・1〆sa (a = constant). g = b (in this case, b corresponds to the speed measurement range) can be approximated by a group of straight lines with negative slopes that change according to known laws, and by forming the complement of the number x according to a certain standard. It is possible to obtain the number y that is (negatively) proportional to the number x.For example, for binary numbers as will be explained later, the following relationship holds true even in the case of an n-bit chairman. In order to approximate the hyperbolic function of y ni (2n - ``As the number of straight lines increases, the degree of approximation to the true velocity curve improves.

When approximating the hyperbola w=c・1/x with a group of straight lines,
Since the proportionality coefficient c is related to various factors, it must be determined experimentally, and each straight line has the formula yi = ni-mi-Xi (
1<ni<2n-1・0<mi<, where 2n-1 is a number corresponding to the speed measurement range).

The number of straight lines is related to the maximum permissible error, with the error being maximum at the intersection of the straight lines. The intersection of the straight lines defines the limits of the speed division of a given speed measurement range and thus also, in practice, the limits of the particular measurement range. At the intersection, so to speak, a cut is made to another measuring range. The measuring device provides a value belonging to a division of the speed measurement range.

This division uniquely corresponds to a straight line that cuts the vertical axis of a particular point, for example y, and the longitudinal axis of the particular point, for example x. It is assumed that the measuring device measures the value x belonging to the category concerned by means of a counter in binary form. The maximum number of counters, 2n-1, corresponds to the speed measurement range.
The above-mentioned straight line is expressed by the formula y=y.--rod-mata. To obtain the corresponding force y from the measured value x clothes, vs.
Multiply this value by multiplying it to find ---x, form the complement of the milk, and get the quantity Z; quantity 2n--Saichi.

Find X, then add the value XI to this quantity and get the excess y・-
issue.

X, that is, the desired value must be found. To implement this method, according to the invention only one frequency is required.

By a relatively simple process consisting of one comparison, two multiplications and one nonami number formation, a measurement result proportional to the rotational speed to be measured can be obtained in a simple manner and in a relatively short time. The dead time between signal generation and measurement results is very short, which means high resolution.

In order to use the multiplied and supplemented measured quantity over a period of time, and to put the measuring device back into the measuring state, the measured quantity is stored and the storage device is returned to its initial state. After the measuring device returns, a new measuring process can be started. Since the device according to the invention requires only a small number of relatively simple parts, costs can be kept low.

Additionally, such a device can be used particularly in harsh conditions such as those encountered when driving a motor vehicle. A pulse generator and a counter are used as measuring devices, the pulse generator is connected to the counter by the signal generated from the detector to give a pulse train of constant frequency, and the counter is connected to the counter by the signal generated from the detector, and the counter It is expedient to count the pulses provided by the generator and to generate an electrical quantity proportional to the signal period time.

A binary counter is preferably used as the counter, so that the measured quantity generated by the counter can be processed very quickly and thus the overall measuring time can be greatly reduced.

In order to increase the operating speed as much as possible and shorten the measurement time, the speed measurement range is divided into four speed categories, and the multiplication value in the first and second arithmetic units is changed from the low speed category to the high speed category. Values of 12, 4 and 8 in sequence, or 8, 4
, 2 and the reciprocal of 1 is expedient.

Since these values correspond to pure binary numbers, the arithmetic unit in the device of the invention can be configured as a simple shift register.

In order to put the measuring device back into the measuring state after the measured variable proportional to the rotational speed has been obtained, the multiplied and supplemented measured values are stored and then returned to the measuring device or the counter.

The invention will be explained in more detail below on the basis of an exemplary embodiment shown in the drawings.

As previously mentioned, the signal period time T has a hyperbolic relationship to the rotational speed.

In the embodiments described here, it is assumed that the measured signal period time is expressed in binary scale z, or else the electrical measured quantity is previously converted to a binary value. . That is, z is proportional to 1'. In order to obtain a proportional relationship between the binary number z corresponding to this z and the rotational speed, the relationship of 1/z of z must be obtained and z must be replaced by z. In contrast, the present invention proposes to form a binary complement from the measured binary value z in order to obtain the (negative) proportionality between z and z. The binary complement of z when the word length is n bits is z = (2n-1) - z.When a certain speed measurement range, for example, 0 to 15 female m/h, is The counting range of the counter (generally 2n for a word length of n bits)
-1) can be made to correspond.

For example, n! If 10 is selected, the maximum count state of the counter will be o-1=1023, which corresponds to the maximum speed to be measured. Now, if we multiply the number z by a given value, for example, 1, 29, 4, and 8 as illustrated in FIG. 1, then the line 1? 293 and 4 (No. 1) are obtained, and after rough complement formation, straight lines 5, 6, 7 and 8 are obtained.

If we now divide the number bound by complement formation by the values 8, 4, 2, and 1 in the opposite order to the above, we will obtain a broken line function consisting of a group of straight lines that approximates a hyperbola.The straight line thus obtained is 9910?11 and 12 are expressed by the following formula: ?Teraze-1-...Z) Here, n = 8, 4 acts 2, 1 and n = 192, 4, 8 The intersection of the straight lines is the female stand of each speed category of the approximate straight line. Define the point and the end point (the proportionality coefficient in the hyperbolic relationship with z is assumed to be 1).

Since the maximum error is determined by the difference between the vertical axis value at the intersection point and the true speed curve for the same machine axis value, it is easy to determine the number of straight lines required to obtain a broken line function that falls within the error limit. be able to.

Once the approximate straight line is determined in this way, the first multiplication value itself and the reciprocal of the second multiplication value (for example, 1, 2, 4, and 8 in this example) are compared and controlled as electrical quantities corresponding to each speed category. It can be stored in the device and used to control the arithmetic device so as to multiply the measured quantity given from the measuring device twice, as described above. In this way, it is possible to obtain a value located on one of the straight line groups and proportional to the rotational speed. FIG. 2 shows an exemplary embodiment of the device according to the invention in the form of a block diagram.

The present invention will be explained below using this block diagram. The device according to the invention has a detector 14 which generates a signal with a frequency proportional to the angular velocity.

This signal is conducted via line 17 and terminal 18 to comparison and control device 6. This comparison and control device furthermore has terminals 20, 22, 24, 2, 69, 28 and 30, the function of which will become clear in the following description of the device according to the invention. The detector signal led to device 16 via terminal 20 opens gate 32 so that pulses of a constant frequency, e.g. For example, a 10-bit binary counter reaches 8. After the signal from the detector 14 disappears, the gate 32 closes again so that the counter 8
This means measuring the period time of the signal. In particular, the binary measured quantity obtained as the count status of the counter 37 is passed via the line 38 and the terminal 22 to the comparison and control device 16.
1 is then compared with a stored electrical quantity at a value corresponding to a given speed section of a predetermined speed measurement range.

The measured quantity is further transmitted via a conductor 39 to an arithmetic unit D!, which is especially designed as a shift register. I will be guided. Depending on the comparison result in the comparison and control unit 6, the terminal 24
One control signal is generated. By the action of this control signal, the measured quantity corresponding to the count state is transferred to the shift register 40.
1 is transferred, and the measured quantity is multiplied by a first given value corresponding to the assigned speed category by means of a comparator. The output signal of the shift register 40, which corresponds to the multiplied measured quantity and is in particular in binary form, is led via a line 41 to an inversion device 42, where a complement (binary complement) is formed from said output signal. Ru. After the reversing device 42 has finished operating, the comparison and control device 16 generates a separate control signal at its terminal 261.

This control signal is conducted via a conductor 43 to a second arithmetic unit 44, the effect of which is to cause an electrical quantity corresponding to the supplemented measured value to be transmitted via a conductor 45 to a arithmetic unit 441, which is configured in particular as a shift register. This is transferred, and the second
is multiplied by a given value of . After the completion of this multiplication, the control device 16 generates a further control signal via the terminal 28 and the conductor turtle 6, the effect of which is to change the electrical quantity of the shift register 44 representing the final measurement result to the conductor 47. The data is then transferred to the storage device 48. The final measured values stored can be recalled via line 49 for further processing. After the storage in the storage device 48 is completed, the control device 16 generates a return pulse, which is transmitted to the terminal 30 and the conductor 5.
After passing through 0, the counter 37 is returned to prepare for a new count.

The obtained measurement results are used at least until the next measurement results are stored.

[Brief explanation of drawings]

FIG. 1 is a graph illustrating the principle of the method according to the invention for simulating the hyperbolic relationship between rotational speed and signal period time by means of an approximate straight line, and FIG. 1 shows a block circuit of a device according to the invention for. 14...detector, 16...comparison and control device, 32.
...Gate, 34, 37...Measuring device, 40
......first arithmetic device, 42...inversion device,
44...Second arithmetic device, 48...Storage device. FIG. lFIG,2

Claims (1)

[Scope of Claims] a) a detector that generates a signal with a frequency proportional to the rotational speed of a rotating member; b) a measuring device that measures the period of the signal; and c) a hyperbola that indicates the relationship between the rotational speed and the period of the detector signal. a memory device for storing electrical quantities corresponding to specific speed divisions of a specific speed measurement range determined by a given group of approximating straight lines of the function, d. A comparison and control device is connected for comparing the measured value of the comparison and control device with said electrical quantity, e and a first shift register is connected to the measuring device, which can be controlled via a control line by the output signal of the comparison and control device. , the number and direction of the control signals of this shift register are determined by the output signals of the comparison and control device, f an inverting device is connected to the first shift register;
g. A second shift register is connected to the inverting device, which can also be controlled via control lines by the output signals of the comparison and control device, the number and direction of the control signals of this shift register also depending on the comparison and control device. Circuit arrangement for the digital measurement of the rotational speed of a rotating member, determined by the output signal h, characterized in that the sum of the control signals of both shift registers corresponds to the slope of an approximate straight line lying within the speed interval.