JPH10185736A - Calibration apparatus for reference torque of torque sensor and steering device using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a calibration apparatus by which the neutral point of a torque sensor can be calibrated properly by a method wherein the reference torque of the torque sensor is calibrated by using the output of the torque sensor in a reference state. SOLUTION: A steering device 1 is provided with a torque sensor 12 which detects a steering torque applied to a steering shaft 10 and with an electronic control unit(ECU) 13. The ECU 13 creates a reference state that the steering torque is not applied to the steering shaft 10, and it calibrates the reference torque of the torque sensor 12 by using the output of the torque sensor 12 in the reference state. Thereby, a reference state that a reference torque is not applied to a shaft part is created by a reference-state creation means, the output of the torque sensor 12 at this time is used as the reference torque, and the neutral point of the torque sensor 12 is calibrated. Thereby, the neutral point of the torque sensor 12 can be calibrated more precisely.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a reference torque calibration device for a torque sensor and a steering device using the same.

[0002]

2. Description of the Related Art Conventionally, as this type of apparatus, for example,
One described in Japanese Utility Model Laid-Open No. 6-65153 is known.

In such a device, when the torque detected by the torque sensor continuously enters a predetermined neutral point setting allowable range for a predetermined torque stabilization time, the maximum value and the minimum value of the detection torque within the torque stabilization time are determined. The average is set as the neutral point of the torque sensor.

[0004]

However, the above-mentioned conventional apparatus has the following problems.

[0005] (1) Since the average of the maximum value and the minimum value of the detected torque that has continued for the torque stabilization time and entered the allowable range of the neutral point setting is adopted as the neutral point of the torque sensor,
When a large deviation that does not fall within the set range occurs (for example, when parking for an extremely long time), the calibration of the neutral point cannot be performed.

(2) If the zero point of the detection signal output from the torque sensor is out of the neutral point setting allowable range, the calibration process cannot be performed.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and can appropriately calibrate the neutral point of the torque sensor regardless of whether the vehicle is stopped or running. It is an object to provide a steering device.

[0008]

A reference torque calibrating device for a torque sensor according to the present invention comprises: a torque sensor for detecting a torque applied to a shaft; and a reference state creating means for generating a reference state in which no torque is applied to the shaft. Means for calibrating the reference torque of the torque sensor using the output of the torque sensor in the reference state, thereby achieving the above object.

[0009] The reference state creating means may comprise a releasing means for releasing the connection between the input side and the output side of the detecting section of the shaft section by the torque sensor.

[0010] The steering apparatus of the present invention comprises: a torque sensor for detecting a steering torque applied to a steering shaft; a reference state creating means for creating a reference state in which the steering torque is not applied to the steering shaft; Using the output, means for calibrating the reference torque of the torque sensor, and a motor for applying a steering force according to the steering torque detected by the torque sensor,
The reference state creating means, when a vibration signal whose amplitude gradually decreases is given to the motor, based on whether an output of the torque sensor output in response to the vibration signal is a constant value, A determination means for determining whether or not the steering torque is applied to the steering shaft is provided, whereby the object is achieved.

[0011] The steering device may further include warning means for issuing a warning when an output of the torque sensor output in response to the vibration signal is not a constant value.

[0012] The vibration signal may be given to the motor immediately after ignition is turned on.

The operation will be described below.

According to the reference torque calibrating device for a torque sensor of the present invention, a reference state in which no torque is applied to the shaft portion is created by the reference state creating means, and the output of the torque sensor at that time is used as the reference torque to neutralize the torque sensor. The points are calibrated. This makes it possible to more accurately calibrate the neutral point of the torque sensor.

[0015]

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

FIG. 1 shows a configuration of an electric power steering apparatus 1 according to an embodiment of the present invention. The steering device 1 is driven by a steering wheel 11 supported on a steering shaft 10, a torque sensor 12 mounted on the steering shaft 10, an electronic control unit (ECU) 13 connected to an output of the torque sensor 12, and an ECU 13. The motor 14 is provided. The motor 14
It is connected to the steering shaft 10 via a speed reducer 15.

When the driver rotates the steering wheel 11 around the steering shaft 10, the steering shaft 1
A steering torque is generated around zero. Torque sensor 12
Detects the steering torque applied to the steering shaft 10. The steering torque can be detected by, for example, the torsion angle between the steering wheel 11 side portion of the steering shaft 10 and the steering gear side portion. The torque sensor 12 outputs a detection signal V ₀ indicating the steering torque to the EC.
Output to U13. ECU13 in response to the detection signal V _0, supplies current to the motor 14. The motor 14 is rotated so as to generate an assist force according to the steering torque generated by the rotation of the steering wheel 11.

The speed reducer 15 includes a pinion 16 mounted on a rotating shaft of a motor 14 and a ring 17 mounted on the steering shaft 10. Pinion 16 and ring 1
7 mesh with each other.

FIG. 2 shows the pinion 1 included in the speed reducer 15.
The relation between 6 and the ring 17 is shown in principle. The gear 21 shown in FIG. 2 corresponds to the pinion 16, and the gear 22 shown in FIG. As shown in FIG. 2, the gear 21 and the gear 22 are meshed with each other with a play angle θ. The play angle θ is determined by the fact that the teeth of the gear 21
Is defined as the angle of rotation before contacting a tooth adjacent to that tooth.

Hereinafter, a calibration process for calibrating the neutral point (0 torque point) of the torque sensor 12 in the steering device 1 will be described.

FIG. 3 is a flowchart showing the procedure of the calibration process. The calibration process shown in FIG.
3 is executed immediately after the ignition is turned on.

In step S1, the ECU 13 supplies a predetermined oscillating current to the motor 14. The predetermined oscillating current is generated by the ECU 13 so that the motor 14 performs a predetermined rotation operation (FIG. 4A).

[0023] FIG. 4 (a) illustrates a predetermined rotational operation of the motor 14 using the rotation angle A _m of the motor 14. From time 0 to time t ₁ , the rotation angle _Am
Vibrates with an amplitude larger than the play angle θ in the speed reducer 15. At time t ₁ ~ time t _2, the rotation angle A _m of the motor 14 oscillates while gradually attenuated smaller amplitude than the play angle θ in the reduction gear 15. Time t ₂ ~ time t ₃
In the rotation angle A _m of the motor 14 oscillates at a sufficiently small constant amplitude than the play angle θ in the reduction gear 15.

[0024] By performing such rotational movement over time 0 time t ₃ to the motor 14, the time t ₂ ~
At time t _3, the gear 21 in the reduction gear 15, the gear 2
That is, one tooth vibrates right and left repeatedly within a range that does not hit any tooth of the gear 22.

FIG. 4B shows a detection signal output from the torque sensor 12 when no steering torque is applied to the steering shaft 10 (for example, when an occupant's hand is not in contact with the steering wheel 11). An example of the waveform of V ₀ is shown. FIG. 4C shows the torque sensor 1 when the steering torque is applied to the steering shaft 10.
2 shows an example of the waveform of the detection signal V ₀ output from the second signal.

In step S2, the ECU 13 sets the time t
Detection signal V ₀ output from the torque sensor 12 at ₂ to time t ₃ is equal to or a constant value. Determining the detection signal V ₀ outputted from the torque sensor 12 whether a constant value, for example, signal detection with the actual rotation angle V _r of the detection signal V ₀ and the motor 14 output from the torque sensor 12 Is achieved by doing

The judgment signal V _j is obtained by passing the result of multiplying the signal V ₀ by the signal V _r through a low-pass filter. If the detection signal V ₀ output from the torque sensor 12 is not a constant value (that is, if the signal V ₀ includes a signal having the same frequency as the signal V _r ), the determination signal V _j becomes 1, and In other cases, the judgment signal _Vj becomes 0. Therefore, by determining the value of the determination signal V _j, it can be the detection signal V ₀ output from the torque sensor 12 to determine whether or not the constant value.

As described above, the motor 14 is caused to perform a predetermined rotation operation from time 0 to time t ₃ (step S1).
At time t ₂ ~ time t ₃ determines the output of the torque sensor 12 (step S2) that, "the state where the steering torque is not applied to the steering shaft 10 (0 torque state)"
Can be determined.

When the value of the determination signal V _j is 0, it indicates that the vehicle is in the 0 torque state, and when the value of the determination signal V _j is 1, it indicates that the vehicle is not in the 0 torque state.

If the determination in step S2 is "YES", the ECU 13 calibrates the neutral point of the torque sensor 12 (step S3). That is, the ECU 13
Calculates the value T ₀ of the neutral point of the torque sensor 12 as (T ₀ + V ₀ )
Rewrite to The value of the neutral point of the torque sensor 12 rewritten in this manner is stored and held in a memory in the ECU 13.

If the determination in step S2 is "NO", the ECU 13 terminates the calibration process without calibrating the neutral point of the torque sensor 12. Or,
The ECU 13 may issue a warning to the driver before ending the calibration process.

As described above, the ECU 13 determines whether or not the state is such that the steering torque is not applied to the steering shaft 10 (0 torque state). Calibrate the neutral point of.
Thus, it is possible to appropriately perform calibration of the neutral point of the torque sensor 12. For example, even when the vehicle is making a steady turn (for example, when the vehicle is traveling on a loop bridge or the like), there is no possibility that the calibration process is erroneously performed.

Alternatively, if the determination in step S2 is "NO", it may be determined whether the battery voltage is smaller than a predetermined value (for example, 10 V).

If the battery voltage is smaller than the predetermined value, a warning is issued to the driver to call attention so as not to touch the steering wheel 11, and the above-described steps S1 to S3 are executed. When the vehicle has been parked for a long period of time, the battery voltage often drops. By detecting that the battery voltage is lower than the predetermined value, the calibration process can be forcibly performed when the ignition is turned on after long-term parking.

Although the above-described calibration processing (FIG. 3) is described as being executed immediately after the ignition is turned on, if a specific condition is satisfied while the vehicle is running (for example, the stop state of the vehicle is detected for several seconds). In such a case, the above-described steps S1 to S3 may be executed. Thereby, the calibration of the neutral point of the torque sensor 12 can be performed more frequently. However, in this case, it is preferable that the rotational angle A _m of the motor 14 to vibrate at a sufficiently small constant amplitude than the play angle θ in the reduction gear 15. This is to avoid affecting the behavior of the steering during running of the vehicle.

Further, to reduce the amplitude of the rotation angle A _m of the motor 14, and, by operating the steering device 1 under vibration is set higher than feel its frequency is human, the steering torque is 0 Can be detected immediately. Thereby, the calibration of the neutral point of the torque sensor 12 can be performed more frequently.

FIG. 5 shows the configuration of the ECU 13 for executing the above-described calibration processing (FIG. 3). ECU13 includes a rotational angle generator 51 for generating a rotation angle A _m of the motor 14,
A motor control unit 52 for controlling the rotation of the motor 14, the transducer (V-I) 53 that converts the voltage output from the motor control unit 52 to the current detection signal V ₀ and the motor output from the torque sensor 12 The signal V _r indicating the actual rotation angle of the fourteen
A signal detection unit 54 outputs a determination signal V _j by the signal detecting the door, neutral determines whether to reset the value of the neutral point of the torque sensor 12 in accordance with the determination signal V _j (T ₀₎ And a point resetting unit 55. When the value of the determination signal _Vj is 0, the value (T ₀ ) of the neutral point of the torque sensor 12 is reset to (T ₀ + V ₀ ).

The ECU 13 is typically a microcomputer including a CPU, a memory, and an input / output interface.

The above-described calibration process (FIG. 3) may be performed after it is detected in advance that the occupant is not touching the steering wheel 11. For example, when a touch sensor is mounted on the steering wheel 11 and the driver does not touch the steering wheel 11, the above-described calibration process is executed. When the driver touches the steering wheel 11, the above-described calibration process is performed. May not be executed.

Also, it is determined whether or not the vehicle is in the zero torque state. If the vehicle is determined to be in the zero torque state, the calibration process is positively created instead of performing the calibration process. You may. For example, the torque sensor 1
All methods of freeing the steering wheel 11 either upstream or downstream of the two are included in the method of creating a zero torque state.

For example, a zero torque state can be created by disposing an electromagnetic clutch upstream or downstream of the torque sensor 12 and disengaging the electromagnetic clutch.
In the steer-by-wire (all electric motor type steering) system, it is also possible to create a zero torque state by separating the reaction force mechanism.

[0042]

According to the reference torque calibrating device for a torque sensor of the present invention, a reference state in which no torque is applied to the shaft portion is created by the reference state creating means, and the output of the torque sensor at that time is used as the reference torque. The neutral point is calibrated. This makes it possible to more accurately calibrate the neutral point of the torque sensor.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an electric power steering device 1 according to an embodiment of the present invention.

FIG. 2 shows a pinion 16 and a ring 1 included in a speed reducer 15;
FIG. 7 is a diagram showing in principle the relationship with No. 7;

FIG. 3 shows a torque sensor 12 in the steering device 1.
9 is a flowchart showing a procedure of a calibration process for calibrating a neutral point (0 torque point) of the first embodiment.

4 (a) is a view showing with the rotation angle A _m of a predetermined rotational operation of the motor 14 the motor 14, (b) and (c), the detection signal V outputted from the torque sensor 12
FIG. 9 is a diagram showing an example of a waveform of ₀ .

FIG. 5 is a diagram showing a configuration of an ECU 13;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Steering device 10 Steering shaft 11 Steering wheel 12 Torque sensor 13 Electronic control unit (ECU) 14 Motor 15 Reduction gear 16 Pinion 17 Ring

Claims (5)

[Claims] 1. A torque sensor for detecting a torque applied to a shaft portion, a reference state creating means for creating a reference state in which no torque is applied to the shaft portion, and the torque using an output of the torque sensor in the reference state. Means for calibrating the reference torque of the sensor. 2. The torque according to claim 1, wherein the reference state generating means comprises a releasing means for releasing connection of an input side or an output side of a detecting section of the shaft section by the torque sensor. Sensor reference torque calibration device. 3. A torque sensor for detecting a steering torque applied to a steering shaft, reference state creating means for creating a reference state in which no steering torque is applied to the steering shaft, and an output of the torque sensor in the reference state. Means for calibrating the reference torque of the torque sensor; and a motor for applying a steering force in accordance with the steering torque detected by the torque sensor. Is determined whether or not the steering torque is applied to the steering shaft based on whether or not the output of the torque sensor output in response to the vibration signal is a constant value. A steering device comprising a determination unit. 4. The steering device according to claim 3, wherein the steering device further includes a warning unit that issues a warning when an output of the torque sensor output in response to the vibration signal is not a constant value. . 5. The steering device according to claim 3, wherein the vibration signal is given to the motor immediately after ignition is turned on.