CN102435164B - Absolute rotator rotation angle measurement method and absolute rotator rotation angle measurement device - Google Patents

Abstract

The invention provides an absolute rotator rotation angle measurement method and an absolute rotator rotation angle measurement device. A measured rotator cooperates with a first measuring rotator and a second measuring rotator to act, the number of the teeth of the first measuring rotator is m, and the number of the teeth of the second measuring rotator is m plus two. The method includes the following steps: choosing the first measuring rotator or the second measuring rotator as a datum measuring rotator, and measuring the relative rotation angle of the datum measuring rotator; acquiring themeasurement cycle number at the absolute rotation angle of the datum measuring rotator; working out the absolute rotation angle of the datum measuring rotator, which is equal to the sum of the product of the measurement cycle number and the measurement cycle of the datum measuring rotator and the relative rotation angle of the datum measuring rotator; and according to the ratio of the teeth of the measured rotator to the teeth of the datum measuring rotator, acquiring the absolute rotation angle Phi of the measured rotator. The method provided by the application is easy to implement, the rotation angle measurement range is wide, and the error is small.

Description

Method and device for measuring absolute rotation angle of rotating body

Technical Field

The present application relates to the field of measurement technologies, and in particular, to a method and an apparatus for measuring an absolute rotation angle of a rotating body.

Background

With the development of modern industry, the degree of the absolute rotation angle of a rotating body needs to be detected on many occasions, especially in the field of automobile industry. In recent years, with the development of the automobile industry, electronic systems such as a vehicle electronic stability system, an automobile reversing auxiliary system, an electronic power steering system, a curve auxiliary system and the like are more and more commonly applied, and all the systems need to work by depending on a steering wheel angle signal. The steering wheel angle is the absolute angle of rotation of the rotating body.

In the related art, there is a rotation angle sensor that can detect an absolute rotation angle of a rotating body. When the absolute rotation angle range is less than 360 degrees, the rotation angle sensor can achieve high precision. However, when the measured rotation angle range exceeds 360 degrees, a problem arises in that the number of revolutions to be made is determined.

In order to measure a rotation angle region larger than 360 degrees, there is a rotation angle measuring device in the prior art for measuring an absolute angle. The rotation angle measuring device can extend the rotation angle measuring range of the rotating body to the area of 1440 degrees by means of a planetary rotary actuator. This device requires a switching ratio of 4 between the control shaft and the transmitter disc to be scanned, and in operation, by placing an encoder on the transmitter disc and scanning with a receiver, the position of the transmitter disc can be detected immediately after switching on the device, and the absolute angle of rotation of the steering wheel can be obtained.

In the process of implementing the invention, the inventor finds that the prior art has at least the following problems: the rotation angle measuring device provided by the prior art needs a planetary rotation transmission device with accurate size and an expensive absolute value sending system, and the measurement range of the rotation angle is limited.

Disclosure of Invention

In order to solve the above technical problem, embodiments of the present application provide a method and an apparatus for measuring an absolute rotation angle of a rotating body, which can measure an absolute rotation angle of a rotating body with a rotation angle range greater than 360 degrees, and the method is simple to implement, and has a larger measurement range of the rotation angle and a smaller error.

The technical scheme is as follows:

a method for measuring the absolute rotation angle of a rotating body to be measured, wherein the number of teeth of the rotating body to be measured is n, the rotating body to be measured is matched with a first rotating measuring body and a second rotating measuring body, the number of teeth of the first rotating measuring body is m, the number of teeth of the second rotating measuring body is m +2, and m +2 are coprime; the method comprises the following steps:

selecting the first measuring rotating body or the second measuring rotating body as a reference measuring rotating body, and measuring to obtain the relative rotation angle of the reference measuring rotating body;

acquiring the number of measurement cycles in which the absolute rotation angle of the reference measurement rotating body is located;

calculating an absolute rotation angle of the reference measuring rotating body, wherein the absolute rotation angle is equal to a sum of a product obtained by multiplying the number of measurement cycles by a measurement cycle of the reference measuring rotating body and a relative rotation angle of the reference measuring rotating body; wherein the measurement period of the reference measurement rotating body is equal to 360 degrees;

and acquiring the absolute rotation angle phi of the measured rotating body according to the gear ratio of the measured rotating body to the reference measuring rotating body, wherein the absolute rotation angle phi is equal to the product of the absolute rotation angle of the reference measuring rotating body and the ratio obtained by dividing the number of teeth of the reference measuring rotating body by the number of teeth of the measured rotating body.

Preferably, when the first measuring rotating body is selected as a reference measuring rotating body, the calculating to obtain the absolute rotation angle of the reference measuring rotating body is specifically:

calculating to obtain the absolute rotation angle beta of the first measuring rotating body₁，β₁＝G₁Ω + Ψ; wherein G is₁Is the absolute angle of rotation beta of the first measuring rotating body₁The number of measurement cycles; Ψ is the measured relative rotation angle of the first measuring rotating body; Ω is a measurement period of the first measurement rotating body, the measurement period being equal to 360 degrees;

the absolute rotation angle phi of the measured rotating body is specifically as follows:

φ＝β₁*m/n。

preferably, the absolute angle of rotation β of the first measuring rotor₁The number of measurement cycles is obtained by:

measuring to obtain a relative rotation angle theta of the second measuring rotating body;

according toThe absolute rotation angle β of the first measuring rotating body is obtained by the following equation₁At the measurement period number G₁：

G₁＝floor[((m+2)/(2*Ω))*Δφ_C]

Wherein floor () is a rounded down function, Δ φ_CA correction value for the angular difference between the relative angle Ψ of the first measuring rotor and the relative angle θ of the second measuring rotor.

Preferably, when the second measuring rotating body is selected as the reference measuring rotating body, the calculating to obtain the absolute rotation angle of the reference measuring rotating body is specifically:

calculating to obtain the absolute rotation angle beta of the second measuring rotating body₂，β₂＝G₂Ω + θ; wherein G is₂Is the absolute angle of rotation beta of the second measuring rotating body₂The number of measurement cycles; theta is the measured relative rotation angle of the second measuring rotating body; Ω is a measurement period of the second measurement rotating body, which is equal to 360 degrees;

the absolute rotation angle phi of the measured rotating body is specifically as follows:

φ＝β₂*(m+2)/n。

preferably, the absolute angle of rotation β of the second measuring rotor₂The number of measurement cycles is obtained by:

measuring to obtain a relative rotation angle psi of the first measuring rotating body;

the absolute rotation angle β of the second measuring rotating body is obtained according to the following formula₂At the measurement period number G₂：

G₂＝floor[(m/(2*Ω))*Δφ_C]

Wherein floor () is a rounded down function, Δ φ_CThe relative rotation angle psi of the first measuring rotating body and the relative rotation angle psi of the second measuring rotating bodyA correction value for the angular difference of the rotational angle theta.

Preferably, the correction value Δ Φ of the angular difference between the relative rotational angle Ψ of the first measuring rotor and the relative rotational angle θ of the second measuring rotor is_CObtained by the following steps:

calculating an angular difference Δ Φ between the relative rotational angle Ψ of the first measuring rotor and the relative rotational angle θ of the second measuring rotor, where Δ Φ — θ;

adjusting the angle difference delta phi to obtain an adjusted angle difference delta phi_C1: if Δ φ is greater than or equal to 0, Δ φ_C1Δ Φ; if Δ φ is less than 0, then Δ φ_C1＝ΔΦ+Ω；

Dividing the rotation range of the measured rotator into two intervals, and judging the delta phi_C1The belonging interval according to the delta phi_C1In the section to which the angle difference belongs, a correction value delta phi of the angle difference is calculated_C。

Preferably, the dividing of the rotation range of the measured rotating body into two intervals is specifically:

setting the rotation range of the measured rotating body as [0, 2 lambda), and dividing the rotation range of the measured rotating body into two intervals, namely [0, lambda) and [ lambda, 2 lambda);

said determining said delta phi_C1The section specifically comprises:

determining a value K from the relative angle Ψ of the first measuring rotor and the relative angle θ of the second measuring rotor:

$K=\left[\frac{(m+2)\mathrm{\θ}-\mathrm{m\ψ}}{\mathrm{\Ω}}\right]$

when the K value is an odd number larger than 1, or the K value is an even number not larger than 0, or the K value is equal to 1 and delta phi is smaller than 0_C1Belongs to [0, λ);

when the K value is an even number larger than 0, or the K value is an odd number smaller than 0, or the K value is 1 and the delta phi is larger than 0, or the delta phi is equal to 0_C1Belongs to [ lambda, 2 lambda);

said dependence of Δ φ_C1In the section to which the angle difference belongs, a correction value delta phi of the angle difference is calculated_CThe method specifically comprises the following steps:

when the said delta phi_C1A correction value of said angular difference Δ φ for [0, λ)_CIs equal to delta phi_C1；

When the said delta phi_C1A correction value of said angular difference Δ φ for [ λ, 2 λ) ]_CEqual to: delta phi_C1+Ω。

The application also provides a device for measuring the absolute rotation angle of the rotating body, which comprises a first measuring rotating body and a second measuring rotating body, wherein the first measuring rotating body and the second measuring rotating body are used for detecting the rotation angle of the measured rotating body; the number of the measured rotating bodies is n, the number of the first measuring rotating bodies is m, the number of the second measuring rotating bodies is m +2, and m +2 are relatively prime;

the device further comprises:

a selection unit: for selecting the first measuring rotating body or the second measuring rotating body as a reference measuring rotating body;

a first angle-of-rotation measuring unit: the relative rotation angle of the reference measuring rotating body is measured;

a measurement cycle number acquisition unit configured to acquire a measurement cycle number at which an absolute rotation angle of the reference measurement rotating body is located;

a reference measuring rotating body absolute rotation angle acquisition unit for calculating an absolute rotation angle of the reference measuring rotating body, wherein the absolute rotation angle is equal to a sum of a product obtained by multiplying the number of measurement cycles by a measurement cycle of the reference measuring rotating body and a relative rotation angle of the reference measuring rotating body; wherein the measurement period of the reference measurement rotating body is equal to 360 degrees;

and the absolute rotation angle value acquisition unit of the measured rotating body is used for acquiring the absolute rotation angle phi of the measured rotating body according to the gear ratio of the measured rotating body to the reference measuring rotating body, wherein the absolute rotation angle phi is equal to the product of the absolute rotation angle of the reference measuring rotating body and the ratio obtained by dividing the number of teeth of the reference measuring rotating body by the number of teeth of the measured rotating body.

Preferably, the selection unit specifically includes:

a first selection unit for selecting the first measuring rotating body as a reference measuring rotating body;

the reference measurement rotating body absolute rotation angle acquisition unit specifically comprises:

a first measuring rotating body absolute rotation angle acquisition unit for calculating and obtaining an absolute rotation angle beta of the first measuring rotating body₁Wherein beta is₁＝G₁Ω + Ψ; wherein G is₁Is the absolute angle of rotation beta of the first measuring rotating body₁The number of measurement cycles; Ψ is the measured relative rotation angle of the first measuring rotating body; Ω is a measurement period of the first measurement rotating body, the measurement period being equal to 360 degrees;

the unit for acquiring the absolute rotation angle of the measured rotating body is specifically as follows:

a first measured rotating body absolute rotation angle acquiring unit for acquiring an absolute rotation angle phi of the measured rotating body according to a gear ratio of the measured rotating body to the first measuring rotating body, wherein phi is beta₁*m/n。

Preferably, the selection unit specifically includes:

a second selection unit for selecting the second measuring rotating body as a reference measuring rotating body;

the reference measurement rotating body absolute rotation angle acquisition unit specifically comprises:

a second measuring rotating body absolute rotation angle acquisition unit for calculating and obtaining an absolute rotation angle beta of the second measuring rotating body₂，β₂＝G₂Ω + θ; wherein G is₂Is the absolute angle of rotation beta of the second measuring rotating body₂The number of measurement cycles; theta is the measured relative rotation angle of the second measuring rotating body; Ω is a measurement period of the second measurement rotating body, which is equal to 360 degrees;

the unit for acquiring the absolute rotation angle of the measured rotating body is specifically as follows:

a second measured rotating body absolute rotation angle acquiring unit for acquiring an absolute rotation angle phi of the measured rotating body according to a gear ratio of the measured rotating body to the second measuring rotating body, wherein phi is beta₂*(m+2)/n。

The beneficial effect of this application does: the application provides a method and a device for measuring the absolute rotation angle of a rotating body, which are used for measuring the absolute rotation angle of the rotating body to be measured by arranging a first measuring rotating body and a second measuring rotating body for the rotating body to be measured, wherein the first measuring rotating body and the second measuring rotating body have m and m +2 tooth numbers respectively and are matched with each other. The technical scheme that this application provided is through selecting first measurement rotator or second measurement rotator as benchmark measurement rotator to through the measurement cycle number that obtains the absolute angle of benchmark measurement rotator is located, calculate and obtain the absolute angle of benchmark measurement rotator, and according to measured rotator with the tooth ratio acquisition of benchmark measurement rotator the absolute angle of measured rotator. This technical solution can be used to accurately measure the absolute rotation angle of the rotating body with a rotation angle range greater than 360 degrees.

The technical scheme provided by the application is simple to realize, and the measuring range of the corner is larger, the error is small, and the measurement is more accurate. According to the method provided by the embodiment of the application, the rotating angle measuring range of the rotating body can be at least 3000 degrees, the measuring range is larger than that of the method in the prior art, and the obtained measuring result is more accurate.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 is a schematic view of a measured rotating body and a position of a measuring rotating body according to an embodiment of the present invention;

FIG. 2 is a flowchart illustrating a method for measuring an absolute rotational angle of a rotating body according to a first embodiment of the present invention;

FIG. 3 is a flowchart illustrating a second embodiment of a method for measuring an absolute rotational angle of a rotating body according to the present invention;

FIG. 4 is a schematic diagram of an angle difference Δ Φ between two measuring rotating bodies within the rotating range of the rotating body to be measured according to the embodiment of the present application;

FIG. 5 is a diagram illustrating an embodiment of the present application, where Δ φ is obtained by adjusting the angular difference Δ φ shown in FIG. 4_C1Two interval schematic diagrams are formed;

FIG. 6 shows an example of the application for Δ φ shown in FIG. 5_C1Corrected to obtain a corrected value delta phi_CA schematic diagram of (a);

FIG. 7 is a flowchart illustrating a method for measuring an absolute rotational angle of a rotating body according to a third embodiment of the present invention;

fig. 8 is a schematic view of an absolute rotation angle measuring device of a rotating body according to an embodiment of the present application.

1-measured rotating body 2-first measuring rotating body 3-second measuring rotating body

Detailed Description

The application provides a method and a device for measuring the absolute rotation angle of a rotating body, which can measure the absolute rotation angle of the rotating body with the rotation angle range larger than 360 degrees, and have simple realization, larger measurement range of the rotation angle and small error. In order to make those skilled in the art better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

First, a method for measuring an absolute rotational angle of a rotating body according to the present invention will be described.

Referring to fig. 1, a schematic diagram of positions of a measured rotating body and a measuring rotating body according to an embodiment of the present application is shown.

As shown in fig. 1, a first measuring rotor 2 and a second measuring rotor 3 are provided for arotor 1 to be measured so as to cooperate with each other. Specifically, the measuredrotating body 1 is engaged with the first measuring rotating body 2 and the second measuring rotating body 3, respectively. The measuredrotating body 1 has n teeth, the number of teeth of the first measuring rotating body 2 is m, the number of teeth of the second measuring rotating body 3 is m +2, and m +2 are relatively prime.

Referring to fig. 2, a flowchart of a first embodiment of the method for measuring an absolute angle of a rotating body according to the present application is shown.

The application provides a method for measuring an absolute rotation angle of a rotating body, which comprises the following steps:

s201, selecting the first measuring rotating body or the second measuring rotating body as a reference measuring rotating body, and measuring to obtain the relative rotation angle of the reference measuring rotating body.

One of the first and second measuring rotating bodies is selected as a reference measuring rotating body, and specifically, any one of the measuring rotating bodies may be selected as the reference measuring rotating body. The relative rotational angle of the reference measuring rotating body can be obtained by a measuring rotating body angle sensor. The sensor for measuring the angle of the rotating body can adopt a contact type or non-contact type sensor, such as a Hall type, a magnetic resistance type, a photoelectric type, an induction type and the like.

And S202, acquiring the measuring period number of the absolute rotation angle of the reference measuring rotating body.

The measuring rotor is typically rotated through several revolutions during the entire measuring period, which is used to indicate that the absolute angle of rotation of the reference measuring rotor is in the fourth measuring period at the current measuring time. For example, the number of measurement cycles may be used to indicate that the absolute angle of rotation of the reference measuring rotating body is in the 1 st measurement cycle, the 2 nd measurement cycle, the 3 rd measurement cycle.

S203, calculating to obtain an absolute rotation angle of the reference measuring rotating body, wherein the absolute rotation angle is equal to a sum of a product obtained by multiplying the number of measuring cycles by the measuring cycle of the reference measuring rotating body and a relative rotation angle of the reference measuring rotating body; wherein the measuring period of the reference measuring rotating body is equal to 360 degrees.

And S204, acquiring the absolute rotation angle phi of the measured rotating body according to the gear ratio of the measured rotating body to the reference measuring rotating body, wherein the phi is equal to the product of the absolute rotation angle of the reference measuring rotating body and the ratio obtained by dividing the gear number of the reference measuring rotating body by the gear number of the measured rotating body.

The method for measuring the absolute rotation angle of the rotating body provided by the embodiment of the application comprises the steps of setting a first measuring rotating body 2 and a second measuring rotating body 3 for a measuredrotating body 1, enabling the first measuring rotating body 2 and the second measuring rotating body 3 to be in a matched action, setting the number of teeth of the first measuring rotating body 2 and the second measuring rotating body 3 to be m and m +2 respectively, enabling m and m +2 to be mutually prime, selecting the first measuring rotating body 2 or the second measuring rotating body 3 as a reference measuring rotating body, and determining the rotation angle of the measuredrotating body 1 according to the tooth number ratio of the measuredrotating body 1 to the reference measuring rotating body by obtaining the absolute rotation angle of the reference measuring rotating body, wherein the range of the measured rotation angle can be more than the absolute rotation angle. According to the method provided by the embodiment of the application, the rotating angle measuring range of the rotating body can be at least 3000 degrees. The technical scheme provided by the application is simple to realize, and the measuring range of the corner is larger, the error is small, and the measurement is more accurate.

Example two:

fig. 3 is a flowchart of a second embodiment of the method for measuring an absolute angle of a rotating body according to the present application, which is described below with reference to the accompanying drawings.

S301, the first surveying rotary body is selected as a reference surveying rotary body, and the relative rotation angle Ψ of the first surveying rotary body 2 is measured.

S302, a relative rotational angle θ of the second measurement rotating body 3 is measured, and an angular difference Δ Φ between the relative rotational angle Ψ of the first measurement rotating body 2 and the relative rotational angle θ of the second measurement rotating body 3 is calculated:

ΔΦ＝Ψ-θ

fig. 4 is a schematic diagram of an angle difference Δ Φ between two measuring rotating bodies within the rotating range of the measured rotating body according to the embodiment of the present application.

Assuming that the rotation range of therotating body 1 to be measured is [0, 1560 ]), the graph shown in fig. 4 is a waveform formed corresponding to the angular difference Δ Φ at each time in the entire rotation range of therotating body 1 to be measured. The abscissa represents the absolute angle of rotation of the measuredrotating body 1 at each time within the range of rotation, and the ordinate represents the angular difference Δ Φ between the two measuring rotating bodies. As can be seen from fig. 4, the value of the angular difference Δ Φ is negative at certain measuring instants.

It is assumed that the measuring period of the first measuring rotor 2 and the second measuring rotor 3 is 360 degrees. When the actual rotational angles of the first and second measuring rotating bodies 2 and 3 are less than 360 degrees, the rotational angle values Ψ and θ measured by the angle sensors are the actual rotational angle values of the measuring rotating bodies. When the actual rotation angles of the first measuring rotating body 2 and the second measuring rotating body 3 are greater than 360 degrees, the rotation angle measured by the angle sensor is a relative rotation angle value, that is, the rotation angle value at this time is an angle value obtained by taking a modulus of the measuring period. For example, assuming that the actual rotational angle of the first measuring rotating body 2 is 370 degrees, the angle measured by the angle sensor is 10 degrees. Assuming that the actual angle of rotation of the second measuring rotor 3 is 270 degrees, the displayed angle of rotation value is 270 degrees. In this case, Δ Φ is 10 to 270 to 260, and Δ Φ is a negative value.

S303, adjusting the angle difference delta phi to obtain an adjusted angle difference delta phi_C1。

As mentioned above, the angular difference Δ Φ between the two measuring rotors may be negative, and in this case, the angular difference between the two measuring rotors needs to be adjusted to be non-negative. Specifically, the method comprises the following steps:

if Δ Φ > -0, Δ Φ_C1＝ΔΦ；

If Δ φ < 0, then Δ φ_C1＝ΔΦ+Ω。

Ω is the measuring period of the first measuring rotor 2 and the second measuring rotor 3, and is typically 360 degrees.

Fig. 5 is a schematic diagram of two intervals formed after the angle difference Δ Φ shown in fig. 4 is adjusted. Wherein the abscissa represents the rotation angle value of the measuredrotating body 1 at each moment in the rotation range, and the ordinate represents the adjusted angle difference value delta phi_C1。

As shown in FIG. 5, the Δ φ is adjusted to obtain Δ φ_C1All are non-negative values, and are within the whole rotation range of the measuredrotating body 1, the value is delta phi at any time_C1Two saw-tooth waves with the same shape are formed.

S304, the measured rotatorThe rotation range is divided into two intervals, and the delta phi is judged_C1The belonging interval according to the delta phi_C1In the section to which the angle difference belongs, a correction value delta phi of the angle difference is calculated_C。

Referring to FIG. 6, for Δ φ shown in FIG. 5_C1Corrected to obtain a corrected value delta phi_CSchematic representation of (a).

Specifically, the rotation range of the measuredrotating body 1 is set to [0, 2 λ), the rotation range of the measuredrotating body 1 is divided into two sections, which are [0, λ) and [ λ, 2 λ), respectively, and the length of each section is λ, and the unit is degree.

As mentioned above, the measuring period of the two measuring rotators is Ω, which is typically 360 degrees. In the rotation range of the measuredrotating body 1, according to the relation of the transmission ratio, the two measuring rotating bodies can rotate for a plurality of circles in the set rotation range, namely, a plurality of measuring periods are output. When the measuredrotating body 1 rotates to the set rotating range value 2 lambda, the number of output cycles of the two measuring rotating bodies in the rotating range of the measuredrotating body 1 has a difference of 2 because the gear ratio of the two measuring rotating bodies is set to be m: m + 2. Here, the difference in the number of output cycles of the two measuring rotating bodies is defined as the difference in the number of rotations of the two measuring rotating bodies within the rotation range of the measuredrotating body 1. For example, if the rotation range of the measuredrotating body 1 is set to [0, 1560 ]), the number of teeth of the measuredrotating body 1 is 45, the number of teeth of the first measuring rotating body 2 is 13, and the number of teeth of the second measuring rotating body 3 is 15, when the measuredrotating body 1 rotates to 1560 degrees, that is, 0 °, the first measuring rotating body 2 rotates 15 turns, the second measuring rotating body 3 rotates 13 turns, and the difference between the two turns, that is, the number of output cycles is 2.

As shown in fig. 5, when the difference between the number of output cycles of the two rotating measuring bodies in the rotating range of therotating body 1 is 2, the angle difference between the two rotating measuring bodies at each time is adjusted to form two sawtooth waves with the same shape. Assuming that the rotation range of the measuredrotating body 1 is [0, 2 lambda ], the rotation range of the measuredrotating body 1 is divided into two sections, and each section degree is lambda. As shown in FIG. 5, assume the measured rotationThe rotation range of thebody 1 is [0, 1560) degrees, assuming that the first sawtooth wave is a first interval [0, 780) and the second sawtooth wave is a second interval [780, 1560). Referring to fig. 5, the abscissa represents the rotation angle value of the measuredrotating body 1 at each moment in the rotation range, and the ordinate represents the adjusted angle difference Δ Φ_C1. By way of example, it can be seen from FIG. 5 that when φ_C1Equal to 150 degrees, it corresponds to two rotation angle values, one in the first interval [0, 780 ] and the other in the second interval [780, 1560 "). In order to determine the final angle of rotation, it is then necessary to measure Δ φ_C1The section is judged according to delta phi_C1The rotation angle phi (absolute rotation angle value) of the measuredrotating body 1 is obtained through calculation.

Specifically, the Δ Φ may be determined according to the positive and negative of the K value, the parity of the K value, and the angle difference Δ Φ_C1The section in which it is located.

Said determining said delta phi_C1The section specifically comprises:

the value K is determined from the relative angle Ψ of the first measuring rotor 2 and the relative angle θ of the second measuring rotor 3:

$K=\left[\frac{(m+2)\mathrm{\&theta;}-\mathrm{m\&psi;}}{\mathrm{\&Omega;}}\right]$

wherein, K is an integer calculated according to the formula, and the error of lambda is introduced by psi and theta can be eliminated by rounding the value of K.

Judging the delta phi according to the positive and negative of the K value, the parity of the K value and the angle difference delta phi_C1The section is as follows:

1. when in the following case, the delta phi_C1Belongs to [0, λ):

when the K value is an odd number greater than 1; or

When the K value is an even number not greater than 0; or

When the K value is equal to 1 and Δ Φ is less than 0, the Δ Φ_C1Belonging to [0, λ).

2. When in the following case, the delta phi_C1Belonging to [ λ, 2 λ):

when the K value is an even number greater than 0; or

When the K value is an odd number less than 0; or

When the value of K is 1 and Δ Φ is greater than 0, or

Or when the delta phi is equal to 0, the delta phi_C1Belonging to [ lambda, 2 lambda ].

Referring to FIG. 6, for Δ φ shown in FIG. 5_C1Corrected to obtain a corrected value delta phi_CSchematic representation of (a).

In particular, said dependence on Δ φ_C1In the belonged interval, calculating to obtain delta phi_CThe method specifically comprises the following steps:

when the said delta phi_C1A correction value of said angular difference Δ φ for [0, λ)_CIs equal to delta phi_C1；

When the said delta phi_C1When it is [ lambda, 2 lambda), the value of Δ φ_CIs equal to delta phi_C1+Ω。

Wherein when the Δ Φ is equal to 0, the Δ Φ_C1At the demarcation point of the interval, Δ φ_CEqual to omega.

S305, obtaining the absolute rotation angle beta of the first measuring rotating body 2 as the reference measuring rotating body₁At the measurement period number G₁。

Wherein G is₁＝floor[((m+2)/(2*Ω))*Δφ_C]

Here, floor () is a rounded down function, Δ φ_CM +2 is the number of teeth of the second measuring rotor 3, which is a correction value for the angular difference between the relative angle Ψ of the first measuring rotor 2 and the relative angle θ of the second measuring rotor 3.

S306, calculating and obtaining the absolute rotation angle value beta of the first measuring rotating body 2 serving as the reference measuring rotating body₁。

Wherein beta is₁＝G₁*Ω+Ψ；

Wherein G is₁Is the absolute angle of rotation beta of the first measuring rotor 2₁The number of measurement cycles, Ω, is typically 360 degrees, Ψ being the measured relative rotation angle value of the first measuring rotor 2.

And S307, acquiring an absolute rotation angle phi of the measuredrotating body 1 according to the gear ratio of the measuredrotating body 1 to the reference measuring rotating body, namely the first measuring rotating body 2.

In particular, phi is beta₁M/n. Where φ is the absolute angle of rotation of therotating body 1 to be measured, β₁Is the absolute angle value of the first measuring rotating body 2, m is the number of teeth of the first measuring rotating body 2, and n is the number of teeth of the measured rotating body.

And S308, outputting the final rotation angle value of the measuredrotating body 1.

Through the steps, the rotation angle of the measuredrotating body 1 is finally obtained through output.

Example three:

in the third embodiment provided by the present application, the absolute rotation angle value of the measuredrotating body 1 can also be obtained by selecting the second measuring rotating body as the reference measuring rotating body, calculating the absolute rotation angle value of the second measuring rotating body 3, and then according to the gear ratio of the measuredrotating body 1 and the second measuring rotating body 3.

Referring to fig. 7, a flow chart of a third embodiment of the method for measuring an absolute angle of a rotating body according to the present application is shown.

And S701, selecting the second measuring rotating body 3 as a reference measuring rotating body, and measuring to obtain the current relative rotation angle theta of the second measuring rotating body 3.

S702, obtaining the current relative rotation angle Ψ of the first measurement rotating body 2, and calculating an angular difference Δ Φ between the relative rotation angle Ψ of the first measurement rotating body 2 and the relative rotation angle θ of the second measurement rotating body 3:

ΔΦ＝Ψ-θ

s703, adjusting the angle difference delta phi to obtain an adjusted angle difference delta phi_C1。

Specifically, the method comprises the following steps:

if Δ Φ > -0, Δ Φ_C1＝ΔΦ；

If Δ φ < 0, then Δ φ_C1＝ΔΦ+Ω。

Ω is the measuring period of the first measuring rotor 2 and the second measuring rotor 3, and is typically 360 degrees.

S704, dividing the rotation range of the measuredrotating body 1 into two intervals, and judging the delta phi_C1The belonging interval according to the delta phi_C1In the section to which the angle difference belongs, a correction value delta phi of the angle difference is calculated_C。

The specific procedure is the same as the calculation method of the second embodiment.

S705, the absolute rotation angle beta of the quasi-measuring rotator, i.e. the second measuring rotator 3 is obtained₂At the measurement period number G₂。

Wherein G is₂＝floor[(m/(2*Ω))*Δφ_C]

Here, floor () is a rounded down function, Δ φ_CThe angle being the relative angle of rotation Ψ of the first measuring rotor 2 and the relative angle of rotation θ of the second measuring rotor 3The correction value for the difference in degrees, m, is the number of teeth of the first measuring rotor 2.

S706, calculating the absolute rotation angle beta of the second measuring rotator 3 as the reference measuring rotator₂。

Wherein beta is₂＝G₂*Ω+θ；

Wherein G is₂Is the absolute angle of rotation beta of the second measuring rotor 3₂The number of measurement cycles, Ω is typically 360 degrees, and θ is the measured relative rotation angle of the second measurement rotating body 3.

And S707, acquiring an absolute rotation angle value phi of the measuredrotating body 1 according to the gear ratio of the measuredrotating body 1 to the quasi-measuring rotating body, namely the second measuring rotating body 3.

In particular, phi is beta₂(m + 2)/n. Where φ is the absolute angle of rotation of therotating body 1 to be measured, β₂The absolute angle value of the second measuring rotor 3, m +2 the number of teeth of the second measuring rotor 3, and n the number of teeth of the measuredrotor 1.

S708, the final rotation angle value of therotating body 1 to be measured is output.

Through the steps, the rotation angle of the measuredrotating body 1 is finally obtained through output.

The application also discloses a measuring device for the absolute rotation angle of the rotating body.

Fig. 8 is a schematic view of an absolute rotation angle measuring device of a rotating body according to an embodiment of the present invention.

The device comprises a first measuring rotating body 2 and a second measuring rotating body 3, which are used for detecting the rotation angle of a measuredrotating body 1; the measuredrotating body 1 has n teeth, and the number of teeth of the first measuring rotating body 2 and the second measuring rotating body 3 is m and m +2, respectively, where m and m +2 are relatively prime.

The device further comprises:

selection unit 801: for selecting the first measuring rotating body or the second measuring rotating body as a reference measuring rotating body;

first angle-of-rotation measuring unit 802: the relative rotation angle of the reference measuring rotating body is measured.

The measurement cycle number acquisition unit 803: the measuring cycle number is used for acquiring the absolute rotation angle of the reference measuring rotating body;

measurement rotating body absolute rotation angle acquisition unit 804: for calculating an absolute angle of rotation of the reference measuring rotating body, wherein the absolute angle of rotation is equal to a sum of a product of the number of measurement cycles times a measurement cycle of the reference measuring rotating body and a relative angle of rotation of the reference measuring rotating body; wherein the measuring period of the reference measuring rotating body is equal to 360 degrees.

Measured-rotator absolute rotation angle acquisition unit 805: and the absolute rotation angle phi of the measured rotating body is obtained according to the gear ratio of the measured rotating body to the reference measuring rotating body, wherein phi is equal to the product of the absolute rotation angle of the reference measuring rotating body and the ratio obtained by dividing the number of teeth of the reference measuring rotating body by the number of teeth of the measured rotating body.

The number of teeth of the first measuring rotating body 2 and the second measuring rotating body 3 may be set by: the difference in the number of teeth between the first measuring rotating body 2 and the second measuring rotating body 3 is 2, the first measuring rotating body 2 has m teeth, the second measuring rotating body 3 has m +2 teeth, and m +2 are coprime.

In the embodiment of the present application, the first rotationangle measuring unit 802 may be specifically configured as an angle sensor, and the angle sensor is used for measuring the relative rotation angle of the reference measurement rotating body. The angle sensor can adopt a contact type or non-contact type sensor, such as a Hall type, a reluctance type, a photoelectric type, an induction type and the like.

Preferably, theselection unit 801 specifically includes:

a first selection unit for selecting the first measuring rotating body as a reference measuring rotating body;

the reference measurement rotating body absolute rotationangle acquiring unit 804 specifically includes:

a first measuring rotating body absolute rotation angle acquisition unit for calculating and obtaining an absolute rotation angle beta of the first measuring rotating body₁Wherein beta is₁＝G₁Ω + Ψ; wherein G is₁Is the absolute angle of rotation beta of the first measuring rotating body₁The number of measurement cycles; Ψ is the measured relative rotation angle of the first measuring rotating body; Ω is a measurement period of the first measurement rotating body, which is equal to 360 degrees.

The measured rotating body absolute rotationangle obtaining unit 805 is specifically:

a first measured rotating body absolute rotation angle acquiring unit for acquiring an absolute rotation angle phi of the measured rotating body according to a gear ratio of the measured rotating body to the first measuring rotating body, wherein phi is beta₁*m/n。

The measurement cyclenumber obtaining unit 803 specifically includes: (ii) a

A first measurement cycle number acquisition unit for acquiring an absolute rotation angle β of the first measurement rotating body₁At the measurement period number G₁；

The first measurement cycle number obtaining unit specifically includes:

a second rotation angle measuring unit for measuring a relative rotation angle θ of the second measurement rotating body;

a cycle number calculating unit for acquiring an absolute rotation angle β of the first measuring rotating body according to the following formula₁At the measurement period number G₁：

G₁＝floor[((m+2)/(2*Ω))*Δφ_C]

Wherein floor () is a floor function，Δφ_CA correction value for the angular difference between the relative angle Ψ of the first measuring rotor and the relative angle θ of the second measuring rotor.

Preferably, theselection unit 801 specifically includes:

a second selection unit for selecting the second measuring rotating body as a reference measuring rotating body;

the reference measurement rotating body absolute rotationangle acquiring unit 804 specifically includes:

a second measuring rotating body absolute rotation angle acquisition unit for calculating and obtaining an absolute rotation angle beta of the second measuring rotating body₂，β₂＝G₂Ω + θ; wherein G is₂Is the absolute angle of rotation beta of the second measuring rotating body₂The number of measurement cycles; theta is the measured relative rotation angle of the second measuring rotating body; Ω is a measurement period of the second measurement rotating body, which is equal to 360 degrees.

The measured rotating body absolute rotationangle obtaining unit 805 is specifically:

a second measured rotating body absolute rotation angle acquiring unit for acquiring an absolute rotation angle phi of the measured rotating body according to a gear ratio of the measured rotating body to the second measuring rotating body, wherein phi is beta₂*(m+2)/n。

The measurement cyclenumber obtaining unit 803 specifically includes:

a second measurement cycle number acquisition unit for acquiring an absolute rotation angle β of the second measurement rotating body₂At the measurement period number G₂；

The second measurement cycle number obtaining unit specifically includes:

the third rotation angle measuring unit is used for measuring and obtaining a relative rotation angle theta of the first measuring rotating body;

a cycle number calculation unit for obtaining the second measurement according to the following formulaAbsolute angle of rotation beta of revolution measuring body₂At the measurement period number G₂：

G₂＝floor[(m/(2*Ω))*Δφ_C]

Wherein floor () is a rounded down function, Δ φ_CA correction value for the angular difference between the relative angle Ψ of the first measuring rotor and the relative angle θ of the second measuring rotor.

Preferably, the device comprises an angular difference correction value acquisition unit for acquiring a correction value Δ Φ of an angular difference between the relative rotational angle Ψ of the first measuring rotating body and the relative rotational angle θ of the second measuring rotating body_C。

Specifically, the angle difference correction value obtaining unit may specifically include:

an angle difference calculation unit for calculating an angle difference Δ Φ between the relative rotational angle Ψ of the first measuring rotor 2 and the relative rotational angle θ of the second measuring rotor 3, where Δ Φ — θ.

An adjusting unit for adjusting the angle difference delta phi to obtain an adjusted angle difference delta phi_C1。

An angle difference correction value calculation unit for dividing the rotation range of the measuredrotating body 1 into two sections and judging the delta phi_C1The belonging interval according to the delta phi_C1In the section to which the angle difference belongs, a correction value delta phi of the angle difference is calculated_C。

The angle difference correction value calculation unit may specifically include:

and an interval dividing subunit, configured to set a rotation range of the measuredrotating body 1 to [0, 2 λ), and divide the rotation range of the measuredrotating body 1 into two intervals, which are [0, λ) and [ λ, 2 λ), respectively).

A section judgment subunit for subtracting the second measuring rotating body from the positive and negative of the K value, the parity of the K value, and the relative rotation angle ψ of the first measuring rotating body 23, the positive and negative of the angle difference delta phi obtained by the relative rotation angle theta are judged_C1The section in which it is located.

A calculation subunit for calculating a difference from the delta phi_C1In the section to which the angle difference belongs, a correction value delta phi of the angle difference is calculated_C。

The interval determination subunit may specifically include:

and a K value calculating unit for calculating a K value from the relative rotation angle Ψ of the first rotating measuring structure 2 and the relative rotation angle θ of the second rotating measuring structure 3:

$K=\left[\frac{(m+2)\mathrm{\&theta;}-\mathrm{m\&psi;}}{\mathrm{\&Omega;}}\right]$

a first judgment unit for judging the delta phi when the K value is an odd number larger than 1, or the K value is an even number not larger than 0, or the K value is equal to 1 and the delta phi is smaller than 0_C1Belonging to [0, λ).

A second determination unit, configured to determine Δ Φ when the K value is an even number greater than 0, or the K value is an odd number less than 0, or the K value is 1 and Δ Φ is greater than 0, or the Δ Φ is equal to 0_C1Belonging to [ lambda, 2 lambda ].

The calculating subunit may specifically include:

a first calculation unit for calculating the value of delta phi_C1When the angle difference belongs to [0, lambda), calculating to obtain a corrected value delta phi of the angle difference_CIs equal to delta phi_C1。

A second calculation unit for calculating the value of delta phi_C1When the angle difference belongs to ([ lambda, 2 lambda), the corrected value delta phi of the angle difference is obtained by calculation_CIs equal to delta phi_C1+Ω。

Further, the apparatus in the embodiment of the present application may further include a rotation angle output device for outputting the finally measured absolute rotation angle of the measuredrotating body 1. Specifically, the rotation angle output device may be connected to an application system, and outputs the measured absolute rotation angle of the measuredrotating body 1 to the application system for use by the application system. The application system works depending on the absolute rotation angle of the measured rotating body. The application system can be an electronic system such as a vehicle electronic stabilizing system, an automobile reversing auxiliary system, an electronic power steering system, a curve auxiliary system and the like.

The application may be described in the general context of computer-executable instructions, such as program modules, being executed by a computer. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. The application may also be practiced in distributed computing environments where tasks are performed by remote processing devices that are linked through a communications network. In a distributed computing environment, program modules may be located in both local and remote computer storage media including memory storage devices.

The foregoing is directed to embodiments of the present application and it is noted that numerous modifications and adaptations may be made by those skilled in the art without departing from the principles of the present application and are intended to be within the scope of the present application.

Claims (4)

1. A method of measuring an absolute rotational angle of a rotating body, characterized in that: the method is used for measuring the absolute rotation angle of a measured rotating body, the number of teeth of the measured rotating body is n, the measured rotating body is matched with a first measuring rotating body and a second measuring rotating body, the number of teeth of the first measuring rotating body is m, the number of teeth of the second measuring rotating body is m +2, and m +2 are relatively prime;

the method comprises the following steps:

selecting the first measuring rotating body or the second measuring rotating body as a reference measuring rotating body, and measuring to obtain the relative rotation angle of the reference measuring rotating body;

acquiring the number of measurement cycles in which the absolute rotation angle of the reference measurement rotating body is located;

calculating an absolute rotation angle of the reference measuring rotating body, wherein the absolute rotation angle is equal to a sum of a product obtained by multiplying the number of measurement cycles by a measurement cycle of the reference measuring rotating body and a relative rotation angle of the reference measuring rotating body; wherein the measurement period of the reference measurement rotating body is equal to 360 degrees;

acquiring an absolute rotation angle phi of the measured rotating body according to the gear ratio of the measured rotating body to the reference measuring rotating body, wherein phi is equal to the product of a ratio obtained by dividing the number of teeth of the reference measuring rotating body by the number of teeth of the measured rotating body and the absolute rotation angle of the reference measuring rotating body;

wherein, when the first measuring rotating body is selected as the reference measuring rotating body, the calculating to obtain the absolute rotation angle of the reference measuring rotating body is specifically as follows: calculating to obtain the absolute rotation angle beta of the first measuring rotating body₁，β₁=G₁Ω + Ψ; wherein G is₁Is the absolute angle of rotation beta of the first measuring rotating body₁The number of measurement cycles; Ψ is the measured relative rotation angle of the first measuring rotating body; Ω is a measurement period of the first measurement rotating body, the measurement period being equal to 360 degrees; the absolute rotation angle phi of the measured rotating body is specifically as follows: phi = beta₁M/n; wherein the absolute angle of rotation β of the first measuring rotating body₁The number of measurement cycles is obtained by: measuring to obtain a relative rotation angle theta of the second measuring rotating body; the absolute rotation angle β of the first measuring rotating body is obtained according to the following formula₁At the measurement period number G₁：G₁=floor[((m+2)/(2*Ω))*Δφ_C](ii) a Wherein floor () is a rounded down function, Δ φ_CA correction value for the angular difference between the relative angle Ψ of the first measuring rotor and the relative angle θ of the second measuring rotor;

or,

when the second measuring screw is selectedWhen the rotating body is used as a reference measuring rotating body, the calculation to obtain the absolute rotation angle of the reference measuring rotating body specifically comprises the following steps: calculating to obtain the absolute rotation angle beta of the second measuring rotating body₂，β₂=G₂Ω + θ; wherein G is₂Is the absolute angle of rotation beta of the second measuring rotating body₂The number of measurement cycles; theta is the measured relative rotation angle of the second measuring rotating body; Ω is a measurement period of the second measurement rotating body, which is equal to 360 degrees; the absolute rotation angle phi of the measured rotating body is specifically as follows: phi = beta₂(m + 2)/n; wherein the absolute angle of rotation β of the second measuring rotating body₂The number of measurement cycles is obtained by: measuring to obtain a relative rotation angle psi of the first measuring rotating body; the absolute rotation angle β of the second measuring rotating body is obtained according to the following formula₂At the measurement period number G₂：G₂=floor[(m/(2*Ω))*Δφ_C]Wherein floor () is a rounded down function, Δ φ_CA correction value for the angular difference between the relative angle Ψ of the first measuring rotor and the relative angle θ of the second measuring rotor.

2. Method according to claim 1, characterized in that the correction value Δ Φ for the angular difference between the relative angle of rotation Ψ of the first measuring rotor and the relative angle of rotation θ of the second measuring rotor is set_CObtained by the following steps:

calculating an angular difference Δ Φ between the relative rotational angle Ψ of the first measurement swivel and the relative rotational angle θ of the second measurement swivel, wherein Δ Φ = Ψ - θ;

adjusting the angle difference delta phi to obtain an adjusted angle difference delta phi_C1: if Δ Φ is 0 or more, Δ Φ_C1= Δ Φ; if Δ φ is less than 0, then Δ φ_C1=ΔФ+Ω；

Dividing the rotation range of the measured rotator into two intervals, and judging the delta phi_C1The belonging interval according to the delta phi_C1In the section to which the angle difference belongs, a correction value delta phi of the angle difference is calculated_C。

3. The method according to claim 2, wherein the dividing of the rotation range of the measured rotating body into two intervals is specifically:

setting the rotation range of the measured rotating body as [0, 2 lambda), and dividing the rotation range of the measured rotating body into two intervals, namely [0, lambda) and [ lambda, 2 lambda);

said determining said delta phi_C1The section specifically comprises:

determining a value K from the relative angle Ψ of the first measuring rotor and the relative angle θ of the second measuring rotor:

$K=\&lsqb;\frac{(m+2)\mathrm{\&theta;}-\mathrm{m\&psi;}}{\mathrm{\&Omega;}}\&rsqb;$

when the K value is an odd number larger than 1, or the K value is an even number not larger than 0, or the K value is equal to 1 and the delta phi is smaller than 0_C1Belongs to [0, λ);

when the K value is an even number greater than 0, or the K value is an odd number less than 0, or the K value is 1 and Δ Φ is greater than 0, or the Δ Φ is equal to 0_C1Belongs to [ lambda, 2 lambda);

said dependence of Δ φ_C1In the section to which the angle difference belongs, a correction value delta phi of the angle difference is calculated_CThe method specifically comprises the following steps:

when the said delta phi_C1A correction value of said angular difference Δ φ for [0, λ)_CIs equal to delta phi_C1；

When the said delta phi_C1A correction value of said angular difference Δ φ for [ λ, 2 λ) ]_CEqual to: delta phi_C1+Ω。

4. A device for measuring the absolute rotation angle of a rotating body, characterized in that:

the device comprises a first measuring rotating body and a second measuring rotating body, and is used for detecting the rotation angle of a measured rotating body; the number of the measured rotating bodies is n, the number of the first measuring rotating bodies is m, the number of the second measuring rotating bodies is m +2, and m +2 are relatively prime;

the device further comprises:

a selection unit: for selecting the first measuring rotating body or the second measuring rotating body as a reference measuring rotating body;

a first angle-of-rotation measuring unit: the relative rotation angle of the reference measuring rotating body is measured;

a measurement cycle number acquisition unit configured to acquire a measurement cycle number at which an absolute rotation angle of the reference measurement rotating body is located;

a reference measuring rotating body absolute rotation angle acquisition unit for calculating an absolute rotation angle of the reference measuring rotating body, wherein the absolute rotation angle is equal to a sum of a product obtained by multiplying the number of measurement cycles by a measurement cycle of the reference measuring rotating body and a relative rotation angle of the reference measuring rotating body; wherein the measurement period of the reference measurement rotating body is equal to 360 degrees;

a measured rotating body absolute rotation angle value obtaining unit configured to obtain an absolute rotation angle Φ of the measured rotating body according to a gear ratio of the measured rotating body to the reference measuring rotating body, where Φ is equal to a product of a ratio obtained by dividing the number of teeth of the reference measuring rotating body by the number of teeth of the measured rotating body and the absolute rotation angle of the reference measuring rotating body;

wherein, the selection unit is specifically:

a first selection unit for selecting the first measuring rotating body as a reference measuring rotating body;

the reference measurement rotating body absolute rotation angle acquisition unit specifically comprises:

a first measuring rotating body absolute rotation angle acquisition unit for calculating and obtaining an absolute rotation angle beta of the first measuring rotating body₁Wherein beta is₁=G₁Ω + Ψ; wherein G is₁Is the absolute angle of rotation beta of the first measuring rotating body₁The number of measurement cycles; Ψ is the measured relative rotation angle of the first measuring rotating body; Ω is a measurement period of the first measurement rotating body, the measurement period being equal to 360 degrees; wherein the absolute angle of rotation β of the first measuring rotating body₁The number of measurement cycles is obtained by: measuring to obtain a relative rotation angle theta of the second measuring rotating body; the absolute rotation angle β of the first measuring rotating body is obtained according to the following formula₁At the measurement period number G₁：G₁=floor[((m+2)/(2*Ω))*Δφ_C](ii) a Wherein floor () is a rounded down function, Δ φ_CA correction value for the angular difference between the relative angle Ψ of the first measuring rotor and the relative angle θ of the second measuring rotor;

the unit for acquiring the absolute rotation angle of the measured rotating body is specifically as follows:

a first measured rotating body absolute rotation angle acquiring unit for acquiring an absolute rotation angle phi of the measured rotating body according to a gear ratio of the measured rotating body to the first measuring rotating body, where phi = beta₁*m/n；

Or,

the selection unit is specifically as follows:

a second selection unit for selecting the second measuring rotating body as a reference measuring rotating body;

the reference measurement rotating body absolute rotation angle acquiring unit is specifically:

a second measuring rotating body absolute rotation angle acquisition unit for calculating and obtaining an absolute rotation angle beta of the second measuring rotating body₂，β₂=G₂Ω + θ; wherein G is₂Is the absolute angle of rotation beta of the second measuring rotating body₂The number of measurement cycles; theta is the measured relative rotation angle of the second measuring rotating body; Ω is a measurement period of the second measurement rotating body, which is equal to 360 degrees; wherein the absolute angle of rotation β of the second measuring rotating body₂The number of measurement cycles is obtained by: measuring the phase of the first measuring rotatorTo the corner Ψ; the absolute rotation angle β of the second measuring rotating body is obtained according to the following formula₂At the measurement period number G₂：G₂=floor[(m/(2*Ω))*Δφ_C]Wherein floor () is a rounded down function, Δ φ_CA correction value for the angular difference between the relative angle Ψ of the first measuring rotor and the relative angle θ of the second measuring rotor;

the unit for acquiring the absolute rotation angle of the measured rotating body is specifically as follows:

a second measured rotating body absolute rotation angle acquiring unit for acquiring an absolute rotation angle phi of the measured rotating body according to a gear ratio of the measured rotating body to the second measuring rotating body, where phi = beta₂*（m+2）/n。

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