JP3228168B2 - Rotation speed detection device and tire generation force detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotational speed detecting device and a tire generating force detecting device, and more particularly to a rotational speed detecting device for estimating an instantaneous speed of a rotating body by an observer constructed using a dynamic model of the rotating body. The present invention relates to a device and a tire generation force detecting device for estimating a braking force acting on wheels using the device.

[0002]

2. Description of the Related Art Conventionally, as a method of detecting the rotation speed of a rotating body such as an electric motor or a vehicle, the position (rotation angle) of the rotating body is detected by using a position detector such as a so-called pulse encoder or pulse generator. There is a method of detecting a rotation speed based on a value of a detected rotation position (hereinafter, also simply referred to as “position”). Generally, the value of the position detector is read at a certain time period, and the rotation speed (hereinafter, also simply referred to as “speed”) is detected by the difference between the detected value at the read timing and the detected value one timing before. Is done.

However, in the case of the above method, since a position which is originally a continuous quantity is detected by a discrete value defined by the resolution of the position detector, problems such as a time delay of the detection speed and quantization noise occur. Furthermore, when the speed is low, a sufficient number of pulses cannot be obtained between the position reading cycles.
The above problem is exacerbated.

Therefore, in order to avoid the above problem, a so-called observer (state observer) is constructed based on a model of the rotating body, and an "instantaneous speed observer" for estimating an instantaneous speed during which no pulse comes by the observer. (Konno, Hori: "Instantaneous speed observer with higher-order disturbance compensation function", IEEJ Transactions on Electronics, D, 112, No6, 1994). Hereinafter, this method will be described. Since the method described in the above-mentioned document describes speed detection in electric motor control, the following description will be made assuming that the rotating body is an electric motor.

FIG. 5 shows the structure of the instantaneous speed observer 10, the electric motor 12, and the position detector 14. As shown in the figure, when obtaining the position of the motor driven to rotate by the input current i, the motor 12 generates a torque coefficient K indicating a conversion coefficient from the current i to the driving torque of the motor.
An adding element of the driving torque and a disturbance torque _Td acting externally on the motor, an inertia J of the motor and an integral element 1
/ S conversion element (1 / Js) and integral element 1 / s
And is represented by Note that s corresponds to the Laplace transform operator.

The operation of the motor 12 will be described. First, when a current i is input, the energy of the current i is converted into a driving torque (Ki) of the motor. For this driving torque, the disturbance torque T _d applied from the electric motor externally applied, the torque acting on the actual electric element becomes total torque T _m. Next, the operation element (1 / Js) is calculated as the reciprocal of inertia J (1 / Js).
J) and the integral element (1 / s), the total torque _Tm is converted into the rotational angular velocity of the armature by (1 / J). s)
Is converted into the rotational speed ω of the armature. Then, the rotation speed ω is converted into an actual rotation position as a continuous amount by an integral element (1 / s) at the subsequent stage.

The actual rotational position of the armature is determined by the position detector 1
4 is detected as a discrete rotational position θ (pulse count value) at each position reading cycle T ₁ .

The instantaneous speed observer 10 has an equivalent model 16 of the electric motor 12 described above. The equivalent model 16 includes a constant unit 20 for a torque coefficient K _n (meaning a nominal value of the torque coefficient K), an adder 22 for adding the estimated value of the calculated value and the disturbance torque of the drive torque, calculator 24 (J _n inertia for calculating a (1 / J _n s) for the estimated value of the total torque acting on the armature J) (nominal value of J) and an integrator 26 that calculates (1 / s) for the calculation result of the calculator 24. In the instantaneous speed observer 10 of FIG. 5, the estimated value of the rotation speed omega, the estimated value of the rotational position theta, an estimate of the disturbance torque T _d and the estimated value of the total torque T _m, was applied a ∧ to each Variable It is represented by

In the equivalent model 16, the current i and the disturbance torque
The control period T of the control system_TwoEvery performance
The calculator 24 outputs the estimated value of the speed of the armature and further integrates it.
The detector 26 outputs the position estimate. That is, the equivalent model
According to rule 16, the control cycle T _TwoOutput the above estimated value every time
Therefore, the reading cycle T of the position detector 14₁Position between
Obtain position and velocity estimates while no information is available.
Can be.

Further, the instantaneous speed observer 10 includes a deviation unit 28 for calculating a deviation Δθ between the position estimated value calculated by the equivalent model 16 and the position θ detected by the position detector 14, A correction gain calculator 18 for calculating the estimated value of the disturbance torque used in the equivalent model 16 and the gain for correcting the estimated value of the speed estimated by the equivalent model 16 for each reading cycle T ₁ , Is provided.

In the instantaneous speed observer 10, the estimated value of the disturbance torque and the estimated value of the speed are corrected by the gain calculated by the correction gain calculator 18 so that Δθ becomes equal to zero. The estimated value substantially coincides with the actual output value of the electric motor 12, so that the rotation speed and the disturbance torque can be accurately estimated.

As the instantaneous speed observer 10 shown in FIG. 5, the above document discloses two modes. The first mode is a “position reading type”, and the second mode is an “average speed reading type”. Hereinafter, each embodiment will be described in more detail.

First, the first mode "position reading type" will be described. FIG. 6 shows the pulse count value corresponding to the position θ, the timing of reading the position by the position detector 14,
And the control cycle. Here, the reading cycle T
It is assumed that T ₁ = mT ₂ , where m is an integer (1), between ₁ and the control cycle T ₂ . Reading cycle T _1, the number as velocity resolution can be obtained sufficiently [ms] ~ several tens [m
s]. In this method, the DSP (Di-
Since assumes the use of high-speed computing device gital Signal Processor), etc., the control period T ₂ are tens [mu
s]. In the first embodiment, the position detector 1
Pulse interval generated from 4 assumes shorter than the control period T _2.

In the reading cycle of the position detector 14, the time t is as follows: t = jT ₁ + kT ₂ , 0 ≦ k <m (2) Here, j is an index (number) sequentially assigned to each section of the reading cycle T ₁ , and k is a reading cycle T
The m each section of the control period T ₂ of the occurring within ₁ of the first interval is an index assigned to the order. When j and k are specified, the time t is determined from the equation (2).
Is represented as f [j, k]. Since f [j, m] = f [j + 1,0], 0 is included in the domain of k in equation (2).

Further, for the estimation of the rotation speed is the estimated value of the disturbance in each control period T ₂ is required, for simplicity,

[0016]

(Equation 1)

Suppose that (3) means that the disturbance takes a constant value in the interval T _2. This assumption is T
_{If 2} is short enough, it is a valid approximation.

Here, the estimated value of the total torque T _m [j, k] acting on the armature at the time point [j, k] is calculated by the constant unit 20 and the adder 22.

[0019]

(Equation 2)

Is calculated. Here, i [j, k] is the current value at the time point [j, k]. Therefore, the arithmetic unit 24
However, by performing trapezoidal integration of the estimated value of the total torque, an estimated value of the speed as in the following equation is obtained.

[0021]

(Equation 3)

Next, the integrator 26 trapezoidally integrates the velocity estimation value of the equation (5) to obtain a position estimation value as shown in the following equation.

[0023]

(Equation 4)

The trapezoidal integration of the equations (5) and (6) is performed at every control cycle T ₂ as described above.

Next, the estimated value of the velocity ω [j, m] according to the equation (5) (appended) and the estimated value of the position θ [j, m] according to the equation (6) (appended) are estimated errors. Is included, so modify as follows.

At the time point [j, m], the position detector 1
4 to obtain an accurate position θ [j, m] = θ [j +
[0], the position estimation error is obtained by the deviation device 28.

[0027]

(Equation 5)

Is obtained. The cause of the estimation error is determined by the initial value T _d [j, 0] of the estimated disturbance vector.
(∧) and initial value ω [j, 0] of estimated speed (∧)
It is thought to be due to the error of If Δθ is written separately for each initial value error, it can be expressed as the following equation.

[0029]

(Equation 6)

## EQU1 ## Here, λ is a weight coefficient vector for distributing the error Δθ to each initial value error. X _err is calculated based on the equation (8), and is used for correcting the initial value in the next speed estimation period [j + 1] as follows.

[0031]

(Equation 7)

Is as follows. Therefore, the correction operation expression is as follows.

[0033]

(Equation 8)

The calculation of equation (10) is performed for each reading cycle of the position detector 14. In addition, the coefficient vector of the second term on the right side of the equation corresponds to the correction gain calculated by the correction gain calculator 18.

Note that λ required for the above calculation is determined as follows. The instantaneous speed observer 10 can be regarded as a kind of minimum-dimensional observer from the viewpoint of control theory. That is, the state quantity of the motor 12 is three, that is, position, speed, and disturbance. However, since the position is known at the time of reading the position detector 14, it has a minimum configuration that estimates only the speed and disturbance.

The convergence characteristics of the estimation error of the instantaneous speed observer 10 are as follows.

[0037]

(Equation 9)

Is given by Here, A and C are electric motors 1
G is an observer gain matrix, and x [j] is a state variable of the system (with an ∧ indicates an estimated value of the state variable).

The pole of the observer is obtained as the root of the following characteristic equation. Here, I is a unit matrix.

| ZI− (A−GCA) | = 0 (12) Here, the gain matrix G is designed so that the root of the above characteristic equation falls within a circle having a radius of 1 centered on the origin on the z plane. For example, the estimation error converges to 0 with time, and the instantaneous speed and the disturbance can be estimated. Since there is a relationship G = LK ^-1 λ between the gain matrix G and the error distribution matrix λ, λ can be determined from this relationship.

Next, a second mode "average speed reading type observer" will be described. The average speed reading type position detector 14 has a function of measuring the pulse interval of the encoder (the time interval between adjacent pulses) as described below, and the rotational position θ is determined based on the measured pulse interval.
Ask for. As described above, in the average speed reading type observer, since the position θ is obtained for each pulse interval, the pulse interval is set to T ₁ . In this case, T ₁ is made variable. Also,
The average speed reading type observer assumes the case where the pulse interval of the encoder is longer than the control period T _2, to correct the estimated value at the control point immediately after the encoder pulse occurs.

FIG. 7 is a timing chart of the average speed reading type observer. In the figure, it is assumed that the high-speed counter for measuring the pulse interval of the encoder is reset at the same time as the arrival of the pulse. Since the pulse interval can be measured by the high-speed counter and the rotation angle per pulse is also known in advance, the average speed <ω [j + 1]> between them is calculated as follows.

[0043]

(Equation 10)

Then, using the interval T ₁ from the control time immediately after the arrival of the pulse to the control time immediately after the arrival of the next pulse and the average speed <ω [j + 1]> therebetween, the time [j +
[1,0] can be approximated by θ [j + 1,0] = θ [j, 0] + <ω [j + 1]> T ₁ (14). In the present invention, the deviation of the time of the control point and the pulse generation timing is assumed to be negligible because large T ₂ degree.

[0045] (13), (14) from the equation, the pulse is found true rotation position θ at the control point immediately after the occurrence, thereafter, the first except algorithm such as error correction is that T ₁ is varied This is exactly the same as the position reading type instantaneous speed observer 10 of the embodiment.

Incidentally, the following method is currently used to detect the wheel speed of a vehicle (for example, Japanese Patent Laid-Open No. Hei 6-92116). That is, the output waveform from the wheel speed sensor that generates an AC signal having a frequency component proportional to the wheel speed attached to the axle is shaped into a pulse waveform, and as shown in FIG.
Request-determined control period T _s pulse number occurred in certain loading period k based on N (k) and sample timing immediately before the rising pulse interval T _w (k). Then, the wheel speed ω (k) in the section k is obtained by the following equation.

Ω (k) = K _w · N (k) / T _w (k) where K _w is a conversion coefficient.

[0048]

However, the above prior art has the following problems.

First, in the first aspect of the instantaneous speed observer in the above invention, since the interval between pulses generated from the position detector is assumed to be shorter than the control period T ₂ ,
It cannot be applied in a low speed range where this assumption does not hold.

[0050] In the second aspect of the instantaneous speed observer, but is applicable to a low speed range, displacement of the time between the control point and the pulse generation time is considered negligible since large T ₂ degree . This is a condition that is satisfied when a high-speed operation device such as a DSP is used. In the present invention, it is assumed that T ₂ has an extremely fast cycle of about several tens [μs]. However, since such a high-speed arithmetic device is generally expensive, there is a problem that the entire apparatus becomes expensive. Furthermore, if an inexpensive low-speed arithmetic device is used,
Control period T ₂ becomes longer, since the displacement time of the control point and the pulse generation time can not be ignored, the error correction is difficult based on the true position detection.

That is, as shown in FIG. 9, the time difference Δt between the pulse generation time and the control time (k = m) increases, and the true position θ ^* and (13), (14) at the control time. The difference from the approximate position θ [j + 1,0] calculated based on the equation, that is, the quantization error becomes so large that it cannot be ignored. Along with this, problems such as an increase in quantization noise, deterioration of robustness against parameter fluctuation, and instability of the observer occur. Further, in the second aspect,
Since the error correction is performed every time a pulse is generated, the calculation of the error correction increases in a high speed region where many pulses are generated.

On the other hand, the conventional wheel speed detecting method detects the average speed during the control cycle, and does not indicate the instantaneous speed at the time of reading. In addition, since there is a difference between the pulse generation time and the reading time, the detection delay and quantization noise increase due to the difference. Further, in the low speed region, such a problem becomes more remarkable because there is a state in which no pulse enters between control periods. Wheel speed is used in a vehicle control device such as an anti-skid device, but such control should be performed by using instantaneous control, and the speed detection by the conventional method requires a higher level of fineness from the reliability of the detected speed. There is a problem that the realization of vehicle control is hindered.

In order to realize more advanced vehicle control,
It is necessary to know the force generated between the tire and the road. At the time of braking, this generated force is called a braking force and can be expressed by the following equation.

[0054]

[Equation 11]

Where J is the moment of inertia of the wheel, ω
Is the wheel acceleration, _Tb is the braking torque, and R is the dynamic load radius of the tire. As is clear from equation (15), wheel acceleration is required to determine the braking force. In the related art, the wheel acceleration is calculated based on the time difference between the wheel speeds. Since the operation of the difference is sensitive to noise, the wheel acceleration is accurately obtained from the wheel speed including the detection delay and the quantization noise. Is virtually impossible. Therefore, a correct value cannot be obtained for the braking force.

As a conventional means for detecting the instantaneous speed and acceleration of a wheel, an AC signal output from a wheel speed sensor and having a frequency component proportional to the wheel speed is converted into a wheel speed using an analog circuit and used for an anti-skid device. (JP-A-56-34551). However, at present, when the entire control device including the processing of the sensor signal is designed as a digital system, the addition of an analog circuit leads to an increase in cost. Furthermore, since the AC signal from the wheel speed sensor is not an accurate sine wave and contains many noise components, there is a problem that a correct instantaneous speed and acceleration cannot be detected. In addition, this conventional technique is applicable only to a wheel speed sensor that generates an AC signal having a frequency component proportional to the wheel speed, and is not applicable to a sensor that generates a non-sine wave signal such as a pulse signal according to the rotation angle. There is a problem that cannot be dealt with.

The present invention has been made in view of the above-mentioned circumstances. Even in a low speed range, the control cycle of the control system is long, and the time lag between the pulse generation time and the control time cannot be ignored. It is another object of the present invention to provide a rotation speed detection device capable of accurately estimating the instantaneous speed of a rotating body and a tire generation force detection device capable of accurately estimating a braking force by using the rotation speed detection device.

[0058]

According to a first aspect of the present invention, a rotational position of a rotating body is detected based on a count value of pulses output by a pulse generator attached to the rotating body. Position detecting means, control torque detecting means for detecting control torque for controlling the rotating body, and a rotating body on which the control torque of the value detected by the control torque detecting means and the disturbance torque of the estimated value act. Based on the model, state estimation means for estimating the rotational speed and rotational position of the rotating body from the given initial value of the rotational speed and rotational position, based on at least the number of pulses output by the pulse generator, Error correction determining means for determining a time point of error correction; and a rotational position detected by the position detecting means at a time point of error correction determined by the error correction determining means. The position error generated between the rotational position estimated by the state estimating means is determined by the error of the disturbance torque estimated value, the error of the initial value of the rotational speed, and the quantization error included in the detected rotational position. And an estimation error correction unit that corrects the estimated value of the disturbance torque used by the state estimation unit and the initial values of the rotation speed and the rotation position based on the position error. .

According to the first aspect of the present invention, when the rotating body rotates, the pulse generator attached to the rotating body outputs a pulse, and the position detecting means detects the rotation of the rotating body based on the output pulse count value. Detect the rotational position. For example, this pulse generator can be realized as a pulse generator that converts an AC signal having a frequency component proportional to the rotation speed into a pulse waveform. Also, the position detecting means
This can be realized as a means for calculating the pulse count value by integrating the number of times of pulse generation, and converting the pulse count value into a rotational position. The pulse generator is not limited to generating an AC signal having a frequency component proportional to the rotation speed as described above, but may generate a signal such as a pulse according to the rotation angle.

Then, the control torque detecting means detects a control torque for controlling the rotating body. When the rotating body is a vehicle wheel, the control torque is a braking torque applied to the wheel by a brake pressure applied to a wheel cylinder, and corresponds to a driving torque for driving a motor when the rotating body is an electric motor.

Further, the state estimating means detects the given rotational speed and rotational position based on the model of the rotating body on which the control torque of the value detected by the control torque detecting means and the disturbance torque of the estimated value act. The rotation speed and the rotation position of the rotating body are estimated from each of the initial values. For example, the total torque acting on the rotating body is obtained by adding the control torque and the disturbance torque, and the rotational angular acceleration of the rotating body when the full torque acts is calculated as a physical quantity (moment of inertia) included in the model of the rotating body. Can be obtained from Then, the rotational speed of the rotating body at this time is obtained from the rotational angular acceleration and the initial value of the rotational speed by an integral operation, and the rotational position at this time is obtained from the rotational speed and the initial value of the rotational position by an integral operation. be able to. As the estimated value of the disturbance torque and each initial value of the rotational speed and the rotational position, initially, a value obtained from a predetermined measured value or an estimated value may be used, but the initial value is corrected by an estimation error correction unit described later. In this case, the state estimating means estimates the rotation speed and the rotation position of the rotating body based on the corrected initial values of the disturbance torque, the rotation speed, and the rotation position.

As described above, while the state estimating means is estimating the rotational speed or the like, the error correcting means determines the time of error correction based on at least the number of pulses output from the pulse generator. For example, the point in time when the pulse is counted a predetermined number of times by the high-speed counter (the high-speed counter is reset at this point) may be determined to be the point in time of error correction. Corresponding to the embodiment). Further, a point in time at which the amount of change in the pulse count value at a predetermined time interval becomes equal to or greater than a predetermined value may be determined as an error correction point.

Conventionally, as a cause of the position error,
Considering only the error of the estimated value of the disturbance torque and the error of the initial value of the rotational speed, correct the estimated value of the disturbance torque and the initial value of the rotational speed based on the position error, and further correct the error of the initial value of the rotational position. (In the second mode, at the time of pulse generation). However, the time point at which the state is specified by the actually corrected initial value is the control time point immediately after the error correction determination time point, and there is a time difference between the two time points. A difference between the true position at the time and a so-called quantization error occurs.

Therefore, according to the present invention, when the time of error correction is determined by the error correcting means, the estimated error correcting means estimates the rotational position detected by the position detecting means and the state estimating means at this time. The error of the position generated between the rotational position and the error of the estimated value of the disturbance torque,
Assuming that it is due to the error of the initial value of the rotational speed and the quantization error included in the detected value of the rotational position, the estimated value of the disturbance torque and the initial values of the rotational speed and the rotational position are corrected based on the position error I do. Since the corrected values are used by the state estimating means, each designated value approaches a true value. The method of distributing the position error to the error of each physical quantity can be obtained, for example, from a constraint condition when designing a control system such that the estimation error converges to zero with time.

As described above, in the present invention, the quantization error included in the initial value of the rotational position together with the error between the estimated value of the disturbance torque and the initial value of the rotational speed is considered, and based on the position error,
Since the estimated value of the disturbance torque, the initial value of the rotational speed, and the initial value of the rotational position are corrected, the estimated speed can be set faster than in the related art, and the estimation error can be reduced. In particular, even when the control cycle of the control system cannot be sufficiently shortened due to the capability of the arithmetic device, and thus the quantization error of the rotation position increases, the rotation speed can be accurately estimated and the quantization noise can be reduced. It is possible to prevent an increase, a deterioration in robustness against parameter fluctuation, and an unstable observer.

Further, by determining the time of error correction based on the number of pulses, it is possible to accurately estimate the rotational speed even in a low speed range where no pulse is generated in the control cycle.

Further, according to the present invention, the error correction judging means according to claim 1, wherein the number of pulses output by the pulse generator during the control cycle of the control system is repeated a predetermined number of times or more becomes equal to or more than a reference value. The time point may be determined to be the time point of error correction.

Thus, by setting the reference value of the number of pulses to an appropriate value, it is possible to avoid an increase in calculation load in a high-speed region, which is seen in the prior art in which an estimation error is corrected every time a pulse is generated. Can be.

According to a second aspect of the present invention, there is provided a position detecting means for detecting a rotational position of a wheel based on a count value of pulses output from a pulse generator attached to a wheel, and a braking torque detecting means for detecting a braking torque of the wheel. Means, based on a model of the wheel on which the braking torque detected by the braking torque detection means and the estimated disturbance torque act, and from the respective initial values of the given rotation speed and rotation position, State estimation means for estimating a rotation speed and a rotation position, error correction judgment means for judging a time point of error correction based on at least the number of pulses output by the pulse generator, and judgment by the error correction judgment means At the time of error correction, a position error generated between the rotation position detected by the position detection means and the rotation position estimated by the state estimation means is calculated. The error of the estimated value of the disturbance torque, the error of the initial value of the rotational speed, and the quantization error included in the detected rotational position are considered to be due to the error of the position. Estimation error correction means for correcting the estimated value and each initial value of the rotation speed and the rotation position, and the disturbance torque and the moving radius of the wheel corrected by the estimation error correction means, as a reaction force from the road surface to the wheel. Tire generating force estimating means for estimating the acting braking force.

According to the second aspect of the present invention, the tire generating force estimating means estimates the braking force acting on the wheels as a reaction force from the road surface based on the disturbance torque corrected by the estimation error correcting means and the moving radius of the wheels. I do. According to the present invention, the disturbance torque can be accurately and stably estimated in both the low speed range and the high speed range in which no pulse is generated in the control cycle, based on the same principle as the rotation speed detection device of claim 1. The braking force can be satisfactorily estimated. Also, since there is no need to use the difference in wheel speed as in the prior art,
It is resistant to various noises and can stably estimate the braking force.

[0071]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a rotational speed detecting device and a tire generating force detecting device according to an embodiment of the present invention will be described in detail with reference to the drawings. (Rotation Speed Detecting Apparatus) FIG. 1 is a block diagram showing the configuration of the rotation speed detecting apparatus according to the embodiment of the present invention. As shown in the figure, the present rotational speed detecting device detects a control torque based on a dynamic model of a rotating body, and a control torque detecting means 30 for detecting a control torque applied to control a rotating body to be measured. A state estimating means 32 for estimating the instantaneous position and instantaneous speed of the rotating body based on the obtained control torque and the estimated disturbance torque; and a pulse generator 37 for generating a pulse for each rotation of the rotating body at a predetermined rotation angle. And position detecting means 38 for detecting the position of the rotating body based on the count value of the pulse output from the pulse generator. The control torque detecting means 30 and the state estimating means 32 can be realized by the equivalent model 16 (FIG. 5) of the conventional instantaneous speed observer 10, but the present invention is not limited to this example.

Further, the present rotational speed detecting device includes an error correction judging means 34 for judging an error correction calculation timing based on the number of pulses from the pulse generator 37 and the count number counted in each control cycle T ₂ . When it is determined that the timing of the error correction operation has been reached, the state estimating means 32
And an estimation error correction unit 36 that corrects the estimated values of the speed, the disturbance torque, and the position based on the difference between the position estimated by the above and the position detected by the position detection unit 38.

Next, the operation of the rotation speed detecting device of FIG. 1 will be described.
3 will be described. In addition, FIG.
In the flowchart, the repetition loop is a control cycle.
T_TwoIs repeated at the timing of
N is a predetermined constant of zero or more. And j is
Index of error correction timing, k is control cycle T _Two
Index of the control timing of the present embodiment.
However, the time t is represented by [j, k] as described above.
You.

[0074] As shown in the flowchart of FIG. 3, first, initializes the respective variables in step 99, then proceeds to repeat the loop which is repeated for each control period T _2. At the beginning of this loop, in step 100, k
Is counted up by one.

At the next step 101, the time [j, k]
, The control torque T _q [j, k] of the rotating body is detected. The control torque is a torque applied to control the rotating body. When the rotating body is an electric motor, the motor current at the point [j, k] is detected by a sensor or the like, and the detected value is converted to the control torque. Is obtained by multiplying by the conversion coefficient of
When the rotating body is a wheel of a vehicle, it is obtained by detecting a wheel cylinder pressure and multiplying the detected value by a conversion coefficient into a brake torque. And the next step 10
In 2, the error correction determining means 34 determines whether the time [j, k-1]
The number of pulses n _p generated from the pulse generator 37 between the time and [j, k] is read.

As described above, the angular acceleration of the rotating body is obtained by dividing the total torque of the control torque and the disturbance _Td applied to the rotating body by the moment of inertia of the rotating body. The angular velocity is obtained by time integration, and the rotational position of the rotating body is obtained by further integrating the angular velocity over time.

Then, the state estimating means 32 executes step 1
In 03, the total torque applied to the rotating body is calculated from the control torque obtained in step 101 and the estimated value of the disturbance torque.
Calculate using equation (4). The estimated value of the disturbance torque is
As will be described later, the correction value is corrected by the error correction calculation to approach the true disturbance torque, but the detected value may be used as the initial value of the disturbance torque before the error correction calculation is performed for the first time. For example, when estimating the braking force acting on the wheels as the disturbance torque, the braking force detected based on the above equation (15) is used as the initial value.

In the next step 105, the state estimating means calculates the estimated value of the speed of the rotating body and the estimated value of the rotational position using the trapezoidal integration by the above equations (5) and (6).

In the next step 106, the error correction judging means 34 calculates the sum n of the number of pulses output by the pulse generator 37 from the time point [j, 0] to the time point [j, k].
Is calculated. In this calculation, the pulse number np read in step 102 is cumulatively added to the pulse number n (n ← n + np). Then, in steps 107 and 108, an error correction determination is made.

That is, in step 107, it is determined whether or not the index k has become equal to or greater than the specified value M. If the determination is negative, the same calculation is repeated from step 100 again. When k is increased by the repetition of the calculation, and a positive determination is made in step 107, it is determined in step 108 whether or not the total number n of the pulses added in step 106 is equal to or greater than a specified value N. Step 108
Is negative, the same calculation is repeated from step 100 again. When the number of pulses increases during the repetitive calculation of this loop and a positive determination is made in step 108, an error correction calculation is performed.

That is, the error correction operation is performed when the total number n of pulses counted until the index k initially set to 1 becomes M or more becomes N or more. The above predetermined value M, the value of N is determined arbitrarily suitably depending on the resolution of the length and pulse generator 37 of the control period T _2.

In the error correction calculation, the following calculation is performed. Since the error correction is performed at the time of the value of k added up to the above processing, the error correction cycle T ₁ is k times the control cycle T _{2 according to} the definition. Therefore, in step 109, from _{T 1 = kT 2 (16)} , determining the error correction period T _1. Note that T ₁ varies according to the frequency of occurrence of the number of pulses to be output. Then, in step 110, the position detecting means 38 calculates the position information at this timing from θ [j + 1,0] = θ [j, 0] + nθ _s (17). Where θ _s is generated from the position detector
The rotation angle per pulse.

[0083] Next, in step 111, whether it is the position θ [j + 1,0] is theta ₁ or obtained by the equation (17). Here, θ ₁ is a rotation angle for one rotation of the rotating body, and expressed in units of radians, θ ₁ = 2
π [rad]. That is, step 111 is to determine whether the rotating body has made one rotation.

At step 111, the position θ [j + 1,0]
If a positive determination is made that θ ₁ or more,
At 12, θ ₁ is subtracted from the estimated values of θ [j + 1,0] and θ [j, k], and the process proceeds to the next step 113. By performing this process, the position is always

[0085]

(Equation 12)

[0108] θ [j + 1, 0], θ
It is possible to prevent an overflow of the estimated value (appended) of [j, k]. If a negative determination is made in step 111, the process immediately proceeds to step 113 without executing the process of step 112.

In the next step 113, step 105
The difference between the estimated position value obtained in step (1) and the position information from the position detecting means obtained in step 110 is obtained as in the following equation.

[0088]

(Equation 13)

In the next step 114, the estimation error correcting means 36 determines the position, velocity, and disturbance to be used for position estimation from the next time point [j + 1,0] based on the difference Δθ obtained in step 113. Is modified as in the following equation.

[0090]

[Equation 14]

Here, λ is a weight coefficient vector for distributing an error which is a feature of the present embodiment. This λ
Has the following roles:

That is, in the prior art, since it is assumed that the control period T ₂ can be made sufficiently short, the difference between the pulse generation time of the pulse generator 37 and the pulse reading time can be ignored at most at T _2. I have. According to this premise, the position detected by the position detecting means 38 can be regarded as accurate. Therefore, the cause of the difference Δθ is determined by the initial value T _d [j, 0] of the estimated disturbance and the speed estimation. It can be attributed to the error of the initial value ω [j, 0] (appended).

However, as described above, the control cycle T ₂
Is not sufficiently short, the difference between the pulse generation time of the position detection means and the position reading time becomes large,
Therefore, the quantization error between the true position at the time of reading the position and the position from the position detecting means increases. If such factors cannot be ignored, under the premise that the cause of Δθ is attributable to the initial value of the estimated disturbance and the initial value of the speed estimation value as in the conventional case, the robustness against the increase in quantization noise and parameter fluctuation And the observer becomes unstable.

Therefore, in the present embodiment, it is considered that the position from the position detecting means 38 includes a position reading error such as a quantization error, and the cause of the difference Δθ is the initial value of the estimated disturbance. It is considered that the position reading error is included together with the initial value of the speed estimation value. In this case, Δ
When θ is written for each error, the following equation is obtained.

[0095]

(Equation 15)

Is as follows. However, Δθ _q represents the position reading error, which means that the estimated error Δθ of λ ₀ is the effect of Δθ _q . In order to calculate x _err based on equation (20) and use it for correcting the initial value in the next estimation period [j + 1], the following is performed.

[0097]

(Equation 16)

Is as follows. Rearranging equation (21),

[0099]

[Equation 17]

This is used for the error correction calculation in step 114. On the other hand, the convergence characteristic of the estimation error at the time of error correction is

[0101]

(Equation 18)

Is obtained. Therefore, in order for the above estimation error to converge to zero with time, the root of the equation | zI- (A-GCA) | May be designed as the gain matrix G.

Between G and λ,

[0104]

[Equation 19]

Since the relationship shown in the following is derived, (25)
By rearranging equation (24) using the equation,

[0106]

(Equation 20)

Is obtained. Therefore, in order to set the pole on the z-plane of the observer to (z ₁ , z ₂ , z ₃ ), the following simultaneous equations may be solved.

[0108]

(Equation 21)

Therefore, λ is the desired characteristic (z ₁ , z ₂ ,
z ₃ ) and solving equation (27).

In step 115, the index j of the error correction timing is counted up by one, and at the same time, in steps 116 and 117, k
, And n are reset to zero, and the flow returns to step 100 to execute the operation of the iterative loop again.

As described above, in the present embodiment, it is assumed that the position from the position detecting means 38 includes a position reading error such as a quantization error, and the cause of the estimated value error is determined by the initial value of the estimated disturbance. It is considered that the error is caused by the error of the initial value of the speed estimation value and the position reading error, and the estimation value is corrected for the position in addition to the disturbance and the speed.

Therefore, the disturbance torque and the position can be stably and accurately estimated even if the position reading error increases when the control period T ₂ cannot be sufficiently shortened due to the capability of the arithmetic device. Further, since the estimation error correction timing is changed in accordance with the number of pulse generations from the position detection means, the estimation error correction is performed for each pulse generation in the high-speed range seen in the prior art (second mode). An increase in calculation load can be avoided.

Further, the difference between the position (rotation angle) obtained from the pulse count value and the true position is considered as one of the estimation error factors, and the position is corrected for error. The speed can be satisfactorily estimated even at a low speed at which no occurrence occurs. (Tire Generating Force Detecting Apparatus) FIG. 2 is a block diagram showing the configuration of the tire generating force detecting apparatus according to the embodiment of the present invention. As shown in the figure, the tire generating force detecting device has the same components (same reference numerals) as those of the rotational speed detecting device of FIG.
Further, there is provided a tire generating force estimating means 40 for detecting the estimated value of the disturbance torque corrected by the estimation error correcting means 36 as a tire generating force (braking force) generated between the tire and the road surface.

Next, the operation of the tire generating force detection device of FIG. 2 will be described with reference to the flowchart of FIG. In the flowchart of FIG. 4, the same operation parts (steps) as those in the flowchart of FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted. Only different operation parts will be described.

As shown in the flowchart of FIG. 4, in step 104, the disturbance torque T acting on the wheels
_d Based on the estimated value of [j, k], the braking force is estimated as follows.

The equation of motion at the time of braking the wheel is:

[0117]

(Equation 22)

Can be expressed by Here, W is the wheel load, P is a conversion coefficient of the wheel cylinder pressure, K is the wheel cylinder pressure to the braking torque T _b. Now, the braking torque detecting step 101, the braking torque is detected to T _q = -KP (29),

[0119]

(Equation 23)

It can be seen that the estimated value of the disturbance torque corresponds to a value obtained by multiplying the braking force μW by the dynamic load radius R of the tire. Then, in step 104, the braking force μW can be estimated by dividing the tire dynamic load radius R from the estimated value of the disturbance torque. Even if the initial value of the disturbance torque is given based on, for example, equation (15) or the like, the estimated value of the disturbance torque is sequentially corrected by the error correction calculation (steps 109 to 114). Therefore, it is possible to accurately estimate the braking force.

Further, if the wheel load W is detected by a sensor or calculation, the friction coefficient μ between the tire and the road surface can be estimated. The estimated braking force, friction coefficient, and the like can be used for an anti-skid device, a vehicle stabilization control device, and the like.

[0122]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, description will be given below of experimental results of operation of a rotation speed detecting device and a tire generating force detecting device according to an embodiment of the present invention. (Rotation Speed Detection Device) The rotation speed detection device according to the present embodiment relates to a rotation speed detection device for a rotating body such as an electric motor or a vehicle wheel (FIG. 1). Treat as a body. Note that there is a correspondence relationship between the motor of the motor and the wheels of the vehicle as shown in Table 1, and the application from the wheel rotation speed detecting device according to the present embodiment to the motor rotation speed detecting device is not applicable. Can be easily obtained by converting various quantities based on the conversion table of FIG.

Further, the rotation speed detecting device according to the present embodiment detects the rotation speed based on the flowchart of FIG. 3, but in the operation experiment of the present embodiment, in the flowchart of FIG. It is set to 1. In a vehicle control, generally the control period T ₂ for a long and a few ms, the set high M, since the estimation error period T ₁ is too long, because M is desirably about 1-2. Further, the resolution of the wheel speed sensor currently mounted on the vehicle is extremely low at 48 pulses per rotation, so that the error correction period T
_This is because, if a pulse is generated even once in one period, better estimation can be realized by performing error correction. Therefore, it is desirable that N is about 1 to 2 times.

In the operation experiment of this embodiment, the braking torque was applied in a stepwise manner while the vehicle was running at a constant speed of 50 km / h, and the instantaneous speed of the front wheels of the vehicle under these conditions was estimated. The control period T ₂ are a 5 ms. Hereinafter, results of the operation experiment will be described with reference to FIGS.

FIG. 11 shows changes over time in the vehicle speed, the wheel speed, and the number of pulses generated in the control cycle under the above conditions. Since the braking torque is applied, the vehicle speed and the wheel speed decrease with time, and the number of pulses in the control cycle also decreases. In particular, when the wheel speed (solid line) decreases to around 25 (km / h), the pulse generation period becomes longer than the control cycle, and a period during which the pulse does not enter during the control cycle also appears.

FIG. 12A shows the speed estimation result of the rotation speed detecting device according to the present embodiment. In the figure,
The dashed line is the true instantaneous speed, and the solid line is the estimated speed value. Since the speed is estimated very well within the speed range of the operation experiment, the dashed line and the solid line overlap.

On the other hand, FIG. 12B shows the result of speed estimation under the same conditions by the instantaneous speed observer of the prior art. According to the results of the present embodiment in FIG. 12A, the wheel speed is well estimated up to the low speed range, whereas FIG.
It can be seen from the estimation result of the prior art of FIG. 2 (b) that the estimation value fluctuates in the low speed range, resulting in an unstable result. This is because the difference between the position (rotation angle) determined from the pulse count value and the true position increases as the speed decreases, but in the related art, the position determined from the pulse count value is treated as the true position and error correction is performed. Because it is. On the other hand, in the embodiment of the present invention, the difference between the position (rotation angle) obtained from the pulse count value and the true position is considered as one of the estimation error factors, and the position is corrected for error. Sometimes the speed can be estimated well.

FIGS. 13 and 14 show the relationship between the estimation error of the instantaneous speed estimation value and the estimated speed in the embodiment of the present invention and the prior art, respectively. In these figures, the horizontal axis is the pole (rad / s) of the observer converted into a continuous time system, and the setting of the estimated speed becomes faster toward the left. The vertical axis represents the estimation error, which means that the error increases as going upward. Further, in the present invention, the specified value M is changed using the integer m in the equation (1) as a parameter in the prior art.
more error correction cycle T ₁ value of m is small is shortened.

In the result of the prior art, as shown in FIG. 14, the error reaches the minimum value at m = 1 and pole = −8 (rad / s), but in the result of the present embodiment, as shown in FIG. And M =
1, the error is minimum at pole = −23 (rad / s). Moreover, the minimum value of the error is smaller in the present embodiment than in the prior art. Therefore, according to the present invention, it can be seen that the estimation speed can be set faster and the estimation error can be reduced as compared with the related art. (Tire generating force detecting device) In the operation experiment of the tire generating force detecting device according to the present embodiment, as in the case of the rotational speed detecting device of the present embodiment, the vehicle is traveling at a constant speed of 50 km / h and the step is started. The braking torque was applied in the same manner, and the braking force generated on the wheels under these conditions was estimated. In the present operation experiment, the control period T ₂ to 5 ms, and M = N = 1 in the flowchart of FIG. Hereinafter, the result of the operation experiment will be described with reference to FIG.

FIG. 15 shows the change over time of the estimated value of the braking force estimated by the tire generating force detection device of this embodiment under the above conditions. In the figure, the broken line indicates the actual value of the actually measured braking force, and the solid line indicates the estimated value of the braking force. Also, for reference, the number of pulses generated during the control cycle is also shown.

As shown in FIG. 15, since the braking torque is applied, the wheel speed decreases with time, the pulse generation period becomes longer than the control cycle, and a period during which no pulse is input appears during the control cycle. . Even in such a low-speed range, in FIG. 15, the degree of coincidence between the true braking force value and the estimated braking force value is extremely good, and it can be seen that the braking force is well estimated.

[0132]

As described above, according to the first aspect of the present invention, the estimated value of the disturbance torque, the initial value of the rotational speed, and the initial value of the rotational position are corrected based on the position error. , The estimation speed can be set faster than the prior art,
In addition, the estimation error can be kept small. In particular, even when the control cycle of the control system cannot be sufficiently shortened due to the capability of the arithmetic device, and thus the quantization error of the rotation position increases, the rotation speed can be accurately estimated and the quantization noise can be reduced. The effect is obtained that it is possible to prevent the increase, the deterioration of the robustness to the parameter fluctuation, and the instability of the observer.

Further, by determining the time of error correction based on the number of pulses, it is possible to accurately estimate the rotational speed even in a low speed range where no pulse is generated in the control cycle.

According to the second aspect of the present invention, the disturbance torque can be accurately and stably obtained in both the low speed range and the high speed range in which no pulse is generated in the control cycle, based on the same principle as the rotation speed detecting device of the first aspect. Therefore, the braking force can always be satisfactorily estimated. Further, since the difference in wheel speed as in the related art is not used, it is resistant to various noises, and the braking force can be stably estimated.
The effect is obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a rotation speed detection device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a tire generation force detection device according to an embodiment of the present invention.

FIG. 3 is a flowchart showing a processing flow of the rotation speed detecting device according to the present embodiment.

FIG. 4 is a flowchart showing a processing flow of the tire generating force detection device according to the present embodiment.

FIG. 5 is a block diagram showing a configuration of a conventional instantaneous speed observer.

FIG. 6 is a diagram showing a position reading timing in the first mode “position reading type” of the conventional instantaneous speed observer.

FIG. 7 is a diagram showing an average speed reading timing in a second mode “average speed reading type” of the conventional instantaneous speed observer.

FIG. 8 is a diagram for explaining a conventional wheel speed calculation method.

FIG. 9 is a diagram for explaining a difference between an average speed reading timing and an error correction timing in the second mode “average speed reading type” of the conventional instantaneous speed observer.

FIG. 10 is a conversion table showing the correspondence between motor parameters and wheel parameters.

FIG. 11 is a diagram showing a temporal change of the vehicle body / wheel speed and the number of pulses in a control cycle used in an operation experiment of the rotation speed detecting device according to the embodiment of the present invention.

12A and 12B are diagrams showing a temporal change of a rotation speed estimated in an operation experiment in the present embodiment, wherein FIG. 12A is a result of estimation by the rotation speed detection device according to the embodiment, and FIG. FIG. 7 is a diagram showing an estimation result of the instantaneous speed observer of FIG.

FIG. 13 is a diagram showing a relationship between an estimation error of an instantaneous speed estimation value and a pole (rad / s) in the rotation speed detection device according to the embodiment.

FIG. 14 is a diagram showing a relationship between an estimation error of an estimated instantaneous speed value in a conventional instantaneous speed observer and a pole (rad / s).

FIG. 15 is a diagram illustrating a result of estimating a braking force of the tire generating force detection device according to the present embodiment and a wheel speed pulse number.

[Explanation of symbols]

 Reference Signs List 30 control torque detecting means 32 state estimating means 34 error correction determining means 36 estimation error correcting means 37 pulse generator 38 position detecting means 40 tire generating force estimating means

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-60-17164 (JP, A) JP-A-8-233840 (JP, A) JP-A-7-89304 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) G01L 5/00 G01P 3/489 H02P 5/00

Claims (2)

(57) [Claims] 1. A position detecting means for detecting a rotational position of a rotating body based on a count value of pulses output from a pulse generator attached to the rotating body, and a control for detecting a control torque for controlling the rotating body. Based on a model of the rotating body on which the control torque of the value detected by the control torque detection means and the disturbance torque of the estimated value act, based on the initial value of the given rotation speed and rotation position, State estimating means for estimating the rotational speed and rotational position of the rotating body from an error correction determining means for determining the time of error correction based on at least the number of pulses output by the pulse generator; and the error correction determining means At the time of the error correction determined by the above, the position generated between the rotational position detected by the position detecting means and the rotational position estimated by the state estimating means. The error of the estimated value of the disturbance torque, the error of the initial value of the rotational speed, and the quantization error included in the detected rotational position, based on the position error, the state estimating means An estimation error correction unit that corrects the estimated value of the disturbance torque to be used and each initial value of the rotation speed and the rotation position. 2. A position detecting means for detecting a rotational position of a wheel based on a count value of a pulse output from a pulse generator attached to the wheel; a braking torque detecting means for detecting a braking torque of the wheel; Based on the model of the wheel on which the braking torque of the value detected by the torque detecting means and the disturbance torque of the estimated value act, the rotational speed and the rotational position of the wheel are obtained from the given initial values of the rotational speed and the rotational position. State estimation means for estimating, at least based on the number of pulses output by the pulse generator, error correction determination means for determining the time of error correction, and at the time of error correction determined by the error correction determination means The error of the position generated between the rotational position detected by the position detecting means and the rotational position estimated by the state estimating means is calculated as the disturbance torque. Based on the error of the constant value, the error of the initial value of the rotational speed, and the quantization error included in the detected rotational position, the estimated value of the disturbance torque and the rotational Estimated error correcting means for correcting the initial values of the speed and the rotational position; and a braking force acting on the wheels as a reaction force from the road surface based on the disturbance torque and the moving radius of the wheels corrected by the estimated error correcting means. A tire generation force estimating means for estimating the tire generation force.