JPH05107017A - Rotation angle detecting apparatus - Google Patents

Abstract

PURPOSE:To achieve the early fail detection on the reading side and the fail detection on the side, which is not read, at the same time by simultaneously reading the first and second sensor signal voltages from both potentiometers, dividing the fail judging area based on one sensor signal voltage into three judging areas of wire breakdown, abnormal voltage and short circuits, and performing the comparison and judgment for the other sensor signal voltage to each other. CONSTITUTION:The first fail judging threshold value is set at the lower voltage side than a crossing voltage and second fail judging threshold value is set at the higher voltage side with a fail-judging-threshold-value setting means (f). When one of first and second potentiometers (c) and (d) becomes wire-breakdown fail, a sensor-fail detecting means (g) detects the wire-breakdown fail in one of the potentiometer (c) or (d) when both first and second sensor signal voltages are less than the first threshold value. When one of the meters (c) and (d) has the abnormal voltage, the detecting means (g) detects the abnormal voltage fail in one meter when one of both signal voltages is located between the first and second threshold values and the other is in the intermediate voltage area. When the meter (c) or (d) has the short-circuit fail, the detecting means (g) detects the short-circuit fail in the meter or (d) when both signals are less than the second threshold value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotation angle detecting device for detecting a rotation angle of a rotating shaft such as a motor shaft of an electric motor for steering a rear wheel, and more particularly to a fail detecting technique for a potentiometer which outputs a sensor signal voltage.

[0002]

2. Description of the Related Art Conventionally, as a rotation angle detecting device for detecting an absolute value of a rotation angle of a rotary shaft which can rotate more than one rotation using two potentiometers, for example, Japanese Patent Laid-Open No. 63-186.
The one described in Japanese Patent No. 102 is known.

According to this conventional source, the sensor signal voltage from two potentiometers, a main potentiometer and a sub-potentiometer, each having a brush and a ring-shaped resistor.
Using e (k) and f (k), on this sensor signal voltage characteristic diagram, as shown in FIG. 8, zones (-2), (-1), (0), (+1), (+ 2) It is subdivided according to or area AL, AH, B, C, and sensor signal voltage e
(k) and f (k) determine which zone and area it belongs to and calculate the absolute steering angle for each zone and area. Basically, the sensor signal voltage from the main potentiometer is used. The dead zone that is inevitably generated by the potentiometer, where e (k) is the main (sensor signal voltage e (k) is e (k) =
0) sensor voltage from subpotentiometer only
I use f (k).

[0004]

However, in such a rotation angle detecting device, when either the main potentiometer or the sub potentiometer fails, the reading is performed by a general fail detecting method. If the sensor signal voltage on the live side suddenly becomes the maximum voltage (short circuit) or suddenly becomes zero voltage (open circuit) due to an unexpected voltage change, there are problems listed below. ..

(1) When the potentiometer on the reading side suddenly fails when calculating the absolute steering angle, the value of the absolute steering angle calculated by the detection delay suddenly changes,
For example, it has a significant effect on the rear wheel steering angle control using the absolute steering angle as a control input.

(2) When the potentiometer on the side that is not read when calculating the absolute steering angle fails
There is no control problem as long as the reading side is normal,
The fail on the unread side cannot be detected until the sensor is switched.

The present invention has been made by paying attention to the above problems, and a rotation angle for detecting an absolute value of a rotation angle of a rotation shaft capable of rotating more than one rotation by using sensor signal voltages from two potentiometers. An object of the detection apparatus is to simultaneously achieve early failure detection on the reading side and failure detection on the non-reading side.

[0008]

In order to solve the above problems, in the rotation angle detecting device of the present invention, the first sensor signal voltage and the second sensor signal voltage are read from both potentiometers at the same time, and one sensor signal voltage fails. The judgment area is divided into three areas, that is, a disconnection judgment area, a voltage abnormality judgment area, and a short-circuit judgment area, and the judgment area is compared with the other sensor signal voltage.

That is, as shown in the claim correspondence diagram of FIG. 1, a first sensor signal voltage having a dead zone, which is provided between the rotary shaft a capable of rotating more than one rotation and the rotary shaft a and the case b, is provided. A first potentiometer c for outputting, and a second potentiometer d provided between the rotating shaft a and the case b for outputting a second sensor signal voltage having a phase difference of 180 ° with the first sensor signal voltage. , A rotation angle absolute value calculating means e for calculating a rotation angle absolute value by alternately selecting a higher sensor signal voltage of the first sensor signal voltage and the second sensor signal voltage within a predetermined signal voltage width range, and a sensor In the signal voltage characteristics, the first sensor signal voltage and the second sensor signal voltage have a boundary voltage that is a crossover voltage between one sensor signal voltage characteristic that changes from the maximum voltage to the dead band voltage at a stretch and the other sensor signal voltage. Then, the fail judgment threshold value setting means f for setting the first fail judgment threshold value on the low voltage side and the second fail judgment threshold value on the high voltage side, and the first sensor signal voltage from both potentiometers c and d. And the second sensor signal voltage are read at the same time, and it is determined whether one sensor signal voltage is less than or equal to the first fail judgment threshold value or is between the first fail judgment threshold value and the second fail judgment threshold value. It is determined whether or not the threshold value is exceeded, and for each determination, it is determined whether the other sensor signal voltage is less than or equal to the first fail determination threshold value, the intermediate voltage range, or more than the second fail determination threshold value. At the same time, at least one is determined. The sensor failure detecting means g for detecting that the potentiometer c or d of is a failure is provided.

[0010]

First, the sensor signal voltage characteristic is a characteristic in which the first sensor signal voltage characteristic and the second sensor signal voltage characteristic changing from zero voltage in the dead zone to the maximum voltage appear alternately with a phase difference of 180 °. The crossover voltage between one sensor signal voltage characteristic that changes from the maximum voltage to the dead band voltage at once and the crossover voltage between the other sensor signal voltage is the boundary, and both characteristics of the voltage level exceeding the crossing voltage and the voltage level of less than the crossing voltage. In terms of characteristics, the first sensor signal voltage and the second sensor signal voltage do not simultaneously appear as two signal voltages at any rotation angle. Therefore, in the fail judgment threshold value setting means f, the first fail judgment threshold value is set on the lower voltage side than the crossing voltage and the second fail judgment threshold value is set on the higher voltage side than the crossing voltage.

When one of the first potentiometer c and the second potentiometer d fails in disconnection, the sensor fail detection means g detects both the first sensor signal voltage and the second sensor signal voltage read at the same time. When the condition of 1 fail judgment threshold value or less is satisfied, at least one of the potentiometers c and d is detected as a disconnection failure regardless of the reading side or the non-reading side.

When the voltage value of one of the first potentiometer c and the second potentiometer d becomes abnormally higher or lower than the normal voltage value, the sensor fail detection means g reads the first voltage value at the same time.
When one of the sensor signal voltage and the second sensor signal voltage satisfies the condition of the intermediate voltage range between the first fail judgment threshold value and the second fail judgment threshold value, the reading side or the non-reading side Regardless of the above, at least one of the potentiometers c and d is detected as a voltage abnormal fail.

When one of the first potentiometer c and the second potentiometer d becomes a short fail, both the first sensor signal voltage and the second sensor signal voltage read simultaneously by the sensor fail detecting means g. When the condition of being equal to or less than the second fail judgment threshold value is satisfied, it is detected that at least one of the potentiometers c and d is a short fail regardless of the reading side or the non-reading side.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

The configuration will be described.

FIG. 2 is a diagram showing a mechanical portion of a motor rotation angle detecting device according to an embodiment of the present invention, and FIG. 3 is an overall system diagram showing a four-wheel steering vehicle to which the motor rotation angle detecting device according to the embodiment is applied.
FIG. 4 is a sectional view showing a specific structure of the electric steering device.

A four-wheel steering vehicle to which the motor rotation angle detecting device of the embodiment corresponding to claim 1 and claim 2 is applied on the rear wheel side is shown in FIG. This is performed by the steering handle 3 and the mechanical link type steering mechanism 4. This is composed of, for example, a steering gear, a pitman arm, a relay rod, side rods 5, 6 and knuckle arms 7, 8.

The rear wheels 9 and 10 are steered by an electric steering device 11. This rear wheel 9,
Between 10, the rack shaft 12 and the side rods 13 and 1
4, the knuckle arms 15 and 16 are connected, and the rack tube 17 in which the rack 12 is inserted has a reduction mechanism 1
8, a motor 19 and a fail-safe solenoid 20 are provided, and the motor 19 and the fail-safe solenoid 20 are provided.
Is a controller 26 for inputting signals from the vehicle speed sensor 21, the front wheel steering angle sensor 22, the stroke sensor 23, the first potentiometer 24, the second potentiometer 25 and the like.
Is controlled by.

The electric steering device 11 is shown in FIG.
As shown in, the rack tube 17 into which the rack 12 is inserted is fixed to the vehicle body via a bracket. At both ends of the rack 12, ball joints 30,
The side rods 13 and 14 are connected via 31. The deceleration mechanism 18 is fixed to the motor pinion 32 connected to the motor shaft 19a (corresponding to a rotation shaft) of the motor 19, a ring gear 33 meshing with the motor pinion 32, the ring gear 33, and the rack gear 12a. The rack and pinion 35 meshes with each other. Therefore, when the motor shaft 19a of the motor 19 rotates, the motor pinion 32 → ring gear 33 → rack pinion 35.
The rotation is transmitted to the rack shaft 12 by the meshing of the rotating rack pinion 35 and the rack gear 12a.
Moves in the axial direction to steer the rear wheels 9 and 10.
The turning amount of the rear wheels 9 and 10 is proportional to the moving amount of the rack shaft 12, that is, the rotation amount of the motor shaft 19a of the motor 19.

The fail safe solenoid 20 includes:
The lock pin 20a is provided so as to be movable back and forth, and when the electronic control system or the like fails, the lock pin 20a is fitted into the lock groove 12b formed in the rack shaft 12 so that the rack shaft 12 is moved to the rear wheels 9 and 10. It is fixed at a position that maintains the neutral rudder angle position.

The potentiometers 24 and 25 are shown in FIG.
Further, as shown in FIG. 4, a motor shaft 19a capable of rotating more than one rotation, a rotor 36 rotatably provided together with the motor shaft 19a, a first brush 37 and a second brush 38 fixed to the rotor 36. A base 40 fixed to a motor case 39 (corresponding to a case), a first conductor 41, a second conductor 42, which are provided on the base 40 in a concentric ring shape around the shaft center of the motor shaft 19a, First resistor 4
3, the second resistor 44, the first output terminal 45 connected to the first conductor 41, the second output terminal 46 connected to the second conductor 42, the first resistor 43 and the 2 dead band conductive portions 47 provided at both ends of the resistor 44,
It is provided with a 5V input terminal 49 and a ground terminal 50 connected via 48.

Then, the first conductor 41 and the first resistor 43
And the first brush 37 that slides in contact with both 41 and 43 and the first
The output terminal 45 allows a wide rotation angle range (about 105
By setting a dead zone in which the signal voltage does not change over a range of 0 °), the first potentiometer 24 that outputs the first sensor signal voltage VSEN1 due to the high output gain is configured in the detection region where the signal voltage changes with respect to the change of the rotation angle. Has been done.

Further, the first sensor signal voltage VSEN1 is set to 1 by the second conductor 42, the second resistor 44, the second brush 38 which slides in contact with the two 42, 44 and the second output terminal 46.
A second potentiometer 25 having a phase difference of 80 ° and outputting the second sensor signal voltage VSEN2 with the same high output gain is configured.

The operation will be described.

FIG. 5 shows the flow of the calculation processing operation of the absolute value of the motor rotation angle performed by the controller 26 based on the sensor signal voltages VSEN1 and VSEN2 from both potentiometers 24 and 25 after the neutral position has been initialized. In the flowchart shown, each step will be described below (corresponding to the rotation angle absolute value calculating means).

In step 51, immediately after the initial setting of the neutral position is performed, the first potentiometer 24 outputs the first
The sensor signal voltage VSEN1 and the second sensor signal voltage VSEN2 from the second potentiometer 25 are read.

Here, the neutral position is initially set based on a sensor signal from the stroke sensor 23 when the ignition switch is turned from OFF to ON.

In step 52, the first sensor signal voltage V
It is determined whether SEN1 is greater than the second sensor signal voltage VSEN2.

When VSEN1> VSEN2 in the judgment of step 52, the routine proceeds to step 53, where it is judged whether VSEN1> 4.5V. When it is determined in step 53 that VSEN1> 4.5V, the process proceeds to step 54, the sensor flag F is set to 0 (using the second potentiometer 25), and the second sensor signal voltage VSEN2 is set as the neutral position voltage Vc. Is set. When VSEN1 ≦ 4.5V is determined in step 53, the process proceeds to step 55, and the sensor flag F is set to 1
(The first potentiometer 24 is used) and the first sensor signal voltage VSEN1 is set as the neutral position voltage Vc.

On the other hand, VSEN1≤VSE in the judgment at step 52.
When N2, the routine proceeds to step 56, where it is judged if VSEN2> 4.5V. Then, in step 56, VSEN2> 4.5V
When it is determined that the sensor flag F is set to 1, the first sensor signal voltage VSEN1 is set.
Is set as the neutral position voltage Vc. When it is determined in step 56 that VSEN2 ≦ 4.5V, the routine proceeds to step 58, where the sensor flag F is set to 0 and the second sensor signal voltage VSEN2 is set as the neutral position voltage Vc.

In step 59, the sensor switching frequency R and the sensor input voltage VN are initialized by the sensor switching frequency R.
Is set to R = 0 (zero), and the neutral position voltage Vc set in any of step 54, step 55, step 57, and step 58 is set as the current sensor input voltage VN.

In step 60, the current sensor input voltage VN is set as the previous sensor input voltage VO one control cycle before as the data updating process.

At steps 61 to 63, the current sensor signal voltage VN is read. At step 61, it is judged if the sensor flag F is F = 0. If F = 0, the routine proceeds to step 62. , The second sensor signal voltage VSEN2 is used as the current sensor input voltage VN.
When F = 1, the routine proceeds to step 63, where the first sensor signal voltage VSEN1 is made the current sensor input voltage VN.

In step 64, it is judged whether or not the absolute value of the difference between the previous sensor input voltage VO one control cycle before and the current sensor signal voltage VN exceeds 3V.

This means that when the sensor signal voltage is sampled in one control cycle (for example, 1 msec) and the voltage suddenly becomes 0 V without exceeding the upper threshold voltage of 4.5 V, the steering wheel is turned to the right. This is performed in order to prevent erroneous determination that the steering direction is the left steering direction regardless of the direction, and the subsequent sensor switching processing. Therefore, if YES is determined, the process proceeds to steps 68 to 71, which is a sensor switching process in the right steering direction.

In step 65, the steering direction is detected depending on whether or not the difference between the current sensor signal voltage VN and the previous sensor input voltage VO one control cycle before exceeds 0.

When (VN-VO)> 0 and the steering direction is rightward, the routine proceeds to step 66, where it is judged whether or not the current sensor signal voltage VN exceeds the upper limit threshold value 4.5V, and When (VN-VO) ≤0 and the steering direction is to the left, the routine proceeds to step 67, where it is judged if the current sensor signal voltage VN is less than the lower limit threshold value 0.5V. That is, in steps 66 and 67, it is determined whether or not the sensor is switched, and 0.5V≤VN≤4.5V.
At the time of, the process such as sensor switching is not performed and the process directly proceeds to step 76.

When VN> 4.5V is satisfied in the right steering direction, the process of changing the sensor flag, changing the input signal, and changing the number of times of switching the sensor is performed in steps 68 to 71. That is, in step 68, the sensor flag F
Is F = 0, and when F = 0, the routine proceeds to step 69, where the sensor flag F is changed to F = 1 and the first sensor signal voltage VSEN1 is the current sensor input voltage V
When N = 1 and F = 1, the routine proceeds to step 70, where the sensor flag F is changed to F = 0 and the second sensor signal voltage VSEN2 is made the current sensor input voltage VN. Then, in step 71, the number of times of sensor switching is R is the number of times of sensor switching number R plus one.

When VN <0.5V is satisfied in the left steering direction, the processing of changing the sensor flag, changing the input signal, and changing the number of times of sensor switching is performed in steps 72 to 75. That is, in step 72, the sensor flag F
Is F = 0, and when F = 0, the routine proceeds to step 73, where the sensor flag F is changed to F = 1 and the first sensor signal voltage VSEN1 is the current sensor input voltage V
When N = 1 and F = 1, the routine proceeds to step 74, where the sensor flag F is changed to F = 0 and the second sensor signal voltage VSEN2 is made the current sensor input voltage VN. Then, in step 75, the number of times the sensor switching number R is subtracted by 1 is set as the sensor switching number R.

Steps 76 and 77 are processing steps for calculating the motor rotation angle absolute value θ N from the neutral position. First, in step 76, the motor rotation angle relative value θ '
Is calculated by the following formula.

Θ ′ = 51 × (VN −VC) The constant 51 is 51 deg / 1V.

In step 77, the absolute value of the motor rotation angle θN is calculated from the relative value of the motor rotation angle θ ′ and the number of times R of sensor switching.
Is calculated by the following formula.

[Theta] N = [theta] '+ 180 * R The above steps 60 to 77 are repeatedly executed until the ignition switch is turned off.

That is, as shown in FIG. 7, in the right steering direction, the higher sensor signal voltage of the first sensor signal voltage VSEN1 and the second sensor signal voltage VSEN2 is within the signal voltage width range of 1.0V to 4.5V. Is alternately selected to calculate the motor rotation angle absolute value θ N, and in the left steering direction, the first sensor signal voltage VSEN1 is within the signal voltage range of 0.5V to 4.0V.
And the higher sensor signal voltage of the second sensor signal voltage VSEN2 are alternately selected to calculate the motor rotation angle absolute value θN. Then, under normal conditions, the sensor signal is output within the voltage range in the right steering direction and the left steering direction described above.

FIG. 6 is a flowchart showing the flow of the fail detection processing operation performed by the controller 26 in parallel with the above-described motor rotation angle absolute value calculation processing.
Each step will be described (corresponding to a sensor fail detecting means).

In the sensor signal voltage characteristics shown in FIG. 7, the first sensor signal voltage VSEN1 and the second sensor signal voltage V
Of SEN2, the first fail judgment threshold of 1.0V and high voltage on the low voltage side with a crossing voltage of 1.5V between one sensor signal voltage characteristic that changes from the maximum voltage to the dead band voltage at a stretch and the other sensor signal voltage Second fail judgment threshold of 2.0V
And are stored and set in advance in the RAM of the controller 26 (corresponding to fail judgment threshold value setting means).

In step 80, the first sensor signal voltage V
SEN1 and the second sensor signal voltage VSEN2 are read.

In step 81, the first sensor signal voltage V
It is determined whether SEN1 is less than or equal to the first fail determination threshold value 1.0V.

In step 82, the first sensor signal voltage V
If SEN1 exceeds the first fail judgment threshold of 1.0V and the second
It is judged whether the fail judgment threshold is less than 2.0V.

In step 83, the first sensor signal voltage V
It is determined whether SEN1 is equal to or higher than the second fail determination threshold value 2.0V.

In step 84, if the condition (VSEN1 ≦ 1) in step 81 is satisfied, the second sensor signal voltage V
It is determined whether or not SEN2 is equal to or less than the first fail determination threshold value 1.0V, and if the condition of step 84 is satisfied, the process proceeds to the fail safe process of step 87.

In step 85, when the condition of step 82 (1 <VSEN1 <2) is satisfied, it is determined whether or not the second sensor signal voltage VSEN2 is within the range of 0.5V to 4.0V, and the condition of step 85 is determined. If the condition is satisfied, the process proceeds to the fail-safe process of step 87.

In step 86, when the condition (2≤VSEN1) in step 83 is satisfied, the second sensor signal voltage V
It is determined whether SEN2 is equal to or higher than the second fail determination threshold value 2.0V, and if the condition of step 85 is satisfied, the process proceeds to the fail safe process of step 87.

If NO at steps 84, 85 and 86, it means that both sensor signal voltages VSEN1 and VSEN2 are normal, and the fail detection process from step 80 is performed again. Repeated.

Next, the operation of the fail detection processing when one of the potentiometers 24 and 25 is failed will be described.

First, as shown in FIG. 7, the sensor signal voltage characteristic shows a characteristic in which the first sensor signal voltage characteristic and the second sensor signal voltage characteristic alternately appear with a phase difference of 180 °, and the maximum. The crossover voltage is 1. When the crossover voltage of 1.5V between one sensor signal voltage characteristic that changes from the voltage (4.5V or more) to the dead band voltage (0V) at once and the other sensor signal voltage is the boundary voltage, 1.
The first sensor signal voltage VSEN1 for both characteristics with a voltage level exceeding 5V and with a voltage level less than 1.5V for the crossover voltage.
With respect to the second sensor signal voltage VSEN2, two signal voltages do not appear at the same time at any rotation angle. Therefore, the first fail judgment threshold value 1.0V is set on the lower voltage side than the crossing voltage 1.5V, and the second fail judgment threshold value 2.0V is set on the higher voltage side than the crossing voltage 1.5V.

(A) When disconnection fails, the first potentiometer 24 and the second potentiometer 25
When one of them becomes a disconnection failure, the flow proceeds from step 80 → step 81 → step 84 → step 87 in the flowchart of FIG.

That is, when the disconnection fails, one of the first sensor signal voltage VSEN1 and the second sensor signal voltage VSEN2 read at the same time falls to 0V. Therefore, VSE
The sensor signal voltage on the normal side of N1 and VSEN2 is the first
If the condition that the fail judgment threshold is 1.0 V or less is satisfied, the flow of steps described above will occur, and both potentiometers 2 regardless of the reading side or the non-reading side.
It is detected that at least one of the potentiometers 4 and 25 has a disconnection failure.

(B) When the output voltage is abnormal: Fail First potentiometer 24 and second potentiometer 25
At the time of failure due to abnormal output voltage such that one of the voltage values becomes higher or lower than the normal voltage value, step 8 in the flowchart of FIG.
The flow proceeds from 0 → step 81 → step 82 → step 82 → step 85 → step 87.

That is, when the output voltage is abnormal, the relationship between the voltage levels of the first sensor signal voltage VSEN1 and the second sensor signal voltage VSEN2 read at the same time, which is not possible under normal conditions, is shown. Therefore, the first sensor signal voltage V
When SEN1 is 1 <VSEN1 <2 and at the same time the second sensor signal voltage VSEN2 satisfies the condition 0.5 ≦ VSEN2 ≦ 4, at least one of the potentiometers 24 and 25 regardless of the reading side or the non-reading side. It is detected that the potentiometer of is a failure due to abnormal voltage.

When VSEN1 is 1 <VSEN1 <2, if normal, VSEN2 becomes 4.5V or more or 0V.

(C) At the time of short fail First potentiometer 24 and second potentiometer 25
When one of them becomes a short fail, in the flowchart of FIG. 6, step 80 → step 81
→ Step 82 → Step 83 → Step 86 → Step 87

That is, at the time of short-fail, one of the first sensor signal voltage VSEN1 and the second sensor signal voltage VSEN2 read simultaneously rises to the maximum voltage. Therefore, if the sensor signal voltage on the normal side of VSEN1 and VSEN2 satisfies the condition that the second fail judgment threshold value is 2.0V or higher, the above flow of steps is performed, and the reading side or the non-reading side is performed. Regardless, at least one of the potentiometers 24 and 25 is detected as having a short fail.

The effect will be described.

(1) Two potentiometers 24, 25
In the motor rotation angle detection device for detecting the absolute value of the motor rotation angle θN using the sensor signal voltages VSEN1 and VSEN2 from, the first sensor signal voltage VSEN1 and the second sensor signal voltage VSEN2 are simultaneously read from both potentiometers 24 and 25. Since the fail judgment area based on the first sensor signal voltage VSEN1 is divided into three areas, that is, a disconnection judgment area, a voltage abnormality judgment area and a short judgment area, a device for making a comparison judgment with the second sensor signal voltage VSEN2 for each area. It is possible to simultaneously achieve early failure detection on the reading side and failure detection on the non-reading side.

That is, even when the potentiometer system on the reading side suddenly fails due to disconnection, the disconnection failure is detected early when the first failure judgment threshold value becomes 1.0 V or less before reaching the zero voltage. Also, if the potentiometer system on the reading side suddenly fails due to a short circuit, an early short failure is detected when the second fail judgment threshold value becomes 2.0 V or more before reaching the maximum voltage. Therefore, the sudden change amount of the motor rotation angle absolute value θ N can be suppressed to 51 deg (corresponding to a voltage of 1 V) at the maximum.

Further, since the sensor signal voltages VSEN1 and VSEN2 are simultaneously read and the failure is detected, the failure on the unread side can be detected before the sensor switching.

(2) When calculating the absolute value of the motor rotation angle θ N, the sensor switching condition is set for the right steering direction and the left steering direction without subdividing the zones or areas where the two sensor signals are used. Since it is a device that selectively uses the two sensor signals only by changing it, the motor rotation angle absolute value θN can be calculated with a simple logic.

That is, the sensor flag F and the neutral position voltage V
c, current sensor input voltage VN, previous sensor input voltage VO
The logic is such that the sensor switching count R is used.

(3) The difference between the current sensor input voltage VN and the previously sampled input voltage VO is monitored, and the difference is 1
When the difference that can be changed in the control cycle is exceeded, the device proceeds to the sensor switching process in the right steering direction, so the upper threshold value is 4.
When the signal voltage suddenly changes to 0V without exceeding 5V, it is possible to prevent the erroneous determination of the left steering direction by skipping the reading of the sensor signal.

(4) Immediately after the neutral position is set, the two potentiometers 24 and 25 having a phase difference are used as potentiometers which output the sensor signal voltages VSEN1 and VSEN2 by the high output gain in the detection region by widening the dead band width. The sensor signal voltage VSEN1 or VSEN2 on the high voltage side is selected as the device for setting the neutral position voltage Vc. Therefore, the detection accuracy of the motor rotation angle absolute value θN is improved by high resolution and the sensor signal voltage is selected high to ensure reliability. It is possible to achieve compatibility with the initial setting of the neutral position voltage Vc.

Although the embodiments have been described above with reference to the drawings, the specific structure is not limited to the embodiments, and modifications and additions within the scope of the present invention are included in the present invention. Be done.

For example, in the embodiment, the application example as the motor rotation angle detection device is shown, but if the rotation angle of the rotation shaft capable of rotating more than one rotation, the rotation of another rotation shaft such as the steering shaft. It can also be applied as an angle detection device.

[0074]

As described above, according to the present invention, in the rotation angle detecting device for detecting the absolute value of the rotation angle of the rotating shaft which can rotate more than one rotation by using the sensor signal voltage from the two potentiometers. , The first sensor signal voltage and the second sensor signal voltage are read from both potentiometers at the same time, and the fail judgment area by one sensor signal voltage is divided into three areas, a disconnection judgment area, a voltage abnormality judgment area, and a short judgment area, Since the means for making a comparison judgment with the other sensor signal voltage for each of them, it is possible to obtain the effect that the early fail detection on the reading side and the fail detection on the non-reading side can be achieved at the same time.

[Brief description of drawings]

FIG. 1 is a claim correspondence diagram showing a rotation angle detection device of the present invention.

FIG. 2 is a diagram illustrating a mechanical portion of a motor rotation angle detection device according to an embodiment.

FIG. 3 is an overall system diagram showing a four-wheel steering vehicle to which the motor rotation angle detection device of the embodiment is applied.

FIG. 4 is a cross-sectional view showing a specific configuration of an electric steering device of a four-wheel steering vehicle.

FIG. 5 is a flowchart showing a flow of a motor rotation angle absolute value calculation processing operation performed by a controller based on sensor signal voltages from both potentiometers after initial setting of a neutral position.

FIG. 6 is a flowchart showing a flow of a sensor fail detection processing operation performed by a controller based on sensor signal voltages from both potentiometers.

FIG. 7 is a sensor signal voltage characteristic diagram output from the first potentiometer and the second potentiometer of the embodiment apparatus.

FIG. 8 is a sensor signal voltage characteristic diagram output from the main potentiometer and the sub potentiometer of the conventional device.

[Explanation of symbols]

 a rotation axis b case c first potentiometer d second potentiometer e rotation angle absolute value calculation means f fail judgment threshold setting means g sensor fail detection means

Claims (1)

[Claims] 1. A rotary shaft capable of rotating more than one rotation, a first potentiometer provided between the rotary shaft and the case for outputting a first sensor signal voltage having a dead zone, and the rotary shaft and the case. A second potentiometer provided between the first sensor signal voltage and a second sensor signal voltage having a phase difference of 180 ° from the first sensor signal voltage; and a first sensor signal voltage and a second potentiometer within a predetermined signal voltage range. A rotation angle absolute value calculating means for alternately selecting a high sensor signal voltage among the sensor signal voltages to calculate a rotation angle absolute value, and in the sensor signal voltage characteristics, a first sensor signal voltage and a second sensor signal voltage The first fail judgment threshold value on the low voltage side and the first fail judgment threshold value on the high voltage side are defined by the crossing voltage between one sensor signal voltage characteristic that changes from the maximum voltage to the dead band voltage at a stretch and the other sensor signal voltage. The fail judgment threshold value setting means for setting the two fail judgment threshold values and the first sensor signal voltage and the second sensor signal voltage are simultaneously read from both potentiometers, and one sensor signal voltage is the first fail judgment threshold value. Below the threshold value, between the first and second fail judgment threshold values, or above the second fail judgment threshold value, and the other sensor signal voltage judges the first fail judgment value for each judgment. A sensor fail detecting means for judging whether a threshold value or less, an intermediate voltage range, or a second fail judgment threshold value or more, and at the same time satisfying that at least one of the potentiometers is a fail. Rotation angle detection device.