JP2008213757A - Vehicular steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately detect a tire angle without using a sensor for detecting the tire angle. <P>SOLUTION: In the vehicular steering device, in the state that mechanical connection of a steering wheel and a steering gear box is disconnected, an operation amount of the steering wheel is converted to an electric signal, a steering motor provided on the steering gear box is driven based on the electric signal to turn a wheel, and a steering reaction force motor connected to the steering wheel is driven according to the operation amount to give the steering reaction force to the steering wheel. The device is provided with a tire angle presumption means for presuming the tire angle from a yaw rate of the vehicle detected by a yaw sensor at traveling of the vehicle; and a tire angle detection means for correcting the presumed tire angle by a value of a rotation angle sensor of the steering motor to detect the tire angle. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a steer-by-wire vehicle steering apparatus, and more particularly to a vehicle steering apparatus that realizes tire angle detection at low cost.

  2. Description of the Related Art Conventionally, as a general vehicle steering apparatus, a structure in which a steering mechanism is connected to a steering wheel and wheels are steered via the steering mechanism by a steering force of the steering wheel is known.

Also, in recent years, the steering mechanism is mechanically separated from the steering wheel, and the steering actuator generates steering power according to the steering amount, and the wheel is transmitted by transmitting this steering power to the steering mechanism. A steer-by-wire (steer-by-wire, hereinafter, abbreviated as “SBW”) vehicle steering apparatus is known (see, for example, Patent Document 1).
JP-A-2005-29016

  However, in the above steer-by-wire vehicle steering system, the steering wheel and the tire are mechanically separated, so the tire angle is detected in addition to the sensor that detects the steering wheel handle angle. There is a problem in that it is necessary to provide a sensor that can increase the cost as compared with a conventional general vehicle steering apparatus.

  Accordingly, the present invention has been made in view of the above-described problems, and an object thereof is to provide a vehicle steering apparatus that can accurately detect a tire angle without using a sensor that detects the tire angle. To do.

The present invention proposes the following matters in order to solve the above problems.
(1) The present invention converts a steering wheel operation amount into an electrical signal in a state in which the mechanical connection between the steering wheel and the steering gear box is cut off, and a steering motor provided in the steering gear box based on the electrical signal. In a vehicle steering apparatus that drives a steering reaction force motor connected to a steering wheel in accordance with the operation amount to apply a steering reaction force to the steering wheel according to the operation amount, Tire angle estimating means (for example, corresponding to the tire angle estimating unit 102 in FIG. 2) for estimating the tire angle from the yaw rate of the vehicle detected by the yaw sensor, and the rotation angle sensor (for example, FIG. 2) of the estimated tire angle. Tire angle detecting means (for example, a tire angle detecting means for detecting a tire angle corrected by a value of resolver 104) It proposes a vehicle steering apparatus characterized by comprising the equivalent) to the tire angle detection unit 103 of FIG. 2, a.

  According to this invention, when the vehicle travels, the tire angle is estimated from the yaw rate of the vehicle, and the estimated tire angle is corrected by the value of the rotation angle sensor of the steering motor to detect the tire angle. That is, by calculating a rough tire angle from the yaw rate of the vehicle and correcting the calculated tire angle with the output signal of the rotation angle sensor of the steering motor having a high detection resolution, it is possible to detect a highly accurate tire angle. .

  (2) The present invention converts a steering wheel operation amount into an electric signal in a state where the mechanical connection between the steering wheel and the steering gear box is cut off, and a steering motor provided in the steering gear box based on the electric signal. In a vehicle steering apparatus for driving a steering reaction force motor connected to a steering wheel in accordance with the operation amount to apply a steering reaction force to the steering wheel. Sometimes, a stroke end detection means (for example, corresponding to the stroke end detection unit 201 in FIG. 4) for detecting the stroke end of the steering wheel from the output change amount of the rotation angle sensor of the steering motor, and the tire angle at the stroke end are determined. Maximum tire angle estimating means for estimating the maximum tire angle (for example, the maximum tire angle in FIG. The tire angle estimation unit 202), and after the vehicle travels, when the estimated maximum tire angle and the tire angle estimated from the yaw rate of the vehicle substantially coincide with each other, the maximum tire angle is determined and the determined Tire angle detection means (for example, a tire angle detection unit in FIG. 4) that detects a tire angle based on the output value of a rotation angle sensor (for example, equivalent to the resolver 104 in FIG. 4) of the steering motor with reference to the maximum tire angle The vehicle steering apparatus is provided with the following.

  According to the present invention, when the vehicle stops, the stroke end is detected from the output change amount of the rotation angle sensor of the steering motor, and the tire angle at the stroke end is estimated as the maximum tire angle. Then, when the vehicle travels, the maximum tire angle is determined when the estimated maximum tire angle and the tire angle estimated from the vehicle yaw rate are substantially the same, and the steering motor is controlled based on the determined maximum tire angle. The tire angle is detected based on the value of the rotation angle sensor. That is, in the state where the yaw rate is not generated, such as the steering wheel stationary steering in the stop state immediately after the start of the SWB system, the tire is steered relatively at a specified ratio with respect to the steering angle of the steering wheel, When the stroke end is reached, the output change amount of the rotation angle sensor of the steering motor becomes substantially zero, and this is used to estimate the maximum tire angle. Then, after the vehicle travels, if the tire angle calculated from the yaw rate of the vehicle substantially matches the estimated maximum tire angle, correction is performed from the value of the rotation angle sensor of the steering motor based on the estimated maximum tire angle. Thus, the tire angle can be detected.

  (3) In the vehicle steering apparatus according to (2), the tire angle detection unit is configured so that the estimated maximum tire angle and the tire angle estimated from the yaw rate of the vehicle after the vehicle travels are substantially equal. Proposed a vehicle steering device characterized in that, when they do not coincide, a tire angle is estimated from the yaw rate, and the estimated tire angle is corrected by a value of a rotation angle sensor of the steering motor to detect the tire angle. ing.

  According to the present invention, when the estimated maximum tire angle and the tire angle estimated from the yaw rate do not substantially coincide with each other, the tire angle is estimated from the yaw rate, and the estimated tire angle is determined by the value of the rotation angle sensor of the steering motor. Correct and detect the tire angle. For example, when a tire rides on a curb or the like on a road, the stroke end cannot be detected only from the output change amount of the rotation angle sensor of the steering motor. Accordingly, when the estimated maximum tire angle and the tire angle estimated from the yaw rate do not substantially coincide with each other, it is determined that the stroke end has not been accurately detected, and the tire angle estimated from the yaw rate is determined by the value of the rotation angle sensor of the steering motor. The tire angle is detected after correction.

  According to the present invention, there is an effect that the tire angle can be accurately detected without using a sensor for detecting the tire angle. Further, since a sensor for detecting the tire angle is unnecessary, there is an effect that the cost of the entire apparatus can be reduced.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
Note that the constituent elements in the present embodiment can be appropriately replaced with existing constituent elements and the like, and various variations including combinations with other existing constituent elements are possible. Therefore, the description of the present embodiment does not limit the contents of the invention described in the claims.

<Configuration of vehicle steering device>
The configuration of the vehicle steering apparatus according to the present embodiment will be described with reference to FIG.
The vehicle steering device 10 mechanically separates the steering mechanism 30 from the steering wheel 21 as a steering member, and generates steering power from the steering actuator 38 according to the steering amount of the steering wheel 21. This is a so-called steer-by-wire (SBW) type vehicle steering apparatus in which the steering mechanism 30 steers the left and right steered wheels 35, 35 by transmitting the steering power to the steering mechanism 30. .

  The steering mechanism 20 of the vehicle steering device 10 includes a steering wheel 21 gripped by the driver, a steering shaft 22 connected to the steering wheel 21, a steering angle sensor 23 that detects the steering angle of the steering wheel 21, and the steering wheel 21. A reaction force motor 24 that generates a steering reaction force (reaction force torque) against the motor, a motor rotation angle sensor 25 that detects the rotation angle of the reaction force motor 24, and a reaction force transmission mechanism 26 that transmits the steering reaction force to the steering shaft 22. And a torque sensor 32 for detecting the torque of the steering shaft 22.

  Here, the reaction force motor 24 is an electric motor, and the reaction force transmission mechanism 26 is coupled to the worm 27 provided on the motor shaft of the reaction force motor 24 and the steering shaft 22, and the worm wheel meshed with the worm 27. 28 is a worm gear mechanism, that is, a booster mechanism. The steering reaction force is an operation resistance added to the steering wheel 21 in the rotational direction.

  The turning mechanism 30 includes an input shaft 31 for inputting a steering force of the steering shaft 22, a rack shaft 34 connected to the input shaft 31 via a rack and pinion mechanism 33, and left and right turning wheels at both ends of the rack shaft 34. Tie rods 36 and 36 and knuckles 37 and 37 that connect 35 and 35 (for example, front wheels), and a steering actuator 38 that adds steering power to the input shaft 31.

  The rack and pinion mechanism 33 includes a pinion 43 formed on the input shaft 31 and a rack 44 formed on the rack shaft 34. The steering actuator 38 includes a steering power motor 45 that generates steering power and a steering power transmission mechanism 46 that transmits the steering power to the input shaft 31. Here, the turning power motor 45 is an electric motor. The turning power transmission mechanism 46 includes a worm 47 provided on the motor shaft of the turning power motor 45 and a worm gear 48 that is coupled to the input shaft 31 and meshed with the worm 47, that is, a boosting mechanism. It is.

  As described above, the vehicle steering apparatus 10 is an end take-off type steering apparatus in which the steering torque is extracted from both ends of the rack shaft 34. Further, the vehicle steering apparatus 10 is configured such that a clutch shaft 51 connects a steering shaft 22 provided on the steering wheel 21 and an input shaft 31 provided on the steering mechanism 30. Specifically, the input shaft 31 is connected to the steering shaft 22 via the clutch mechanism 51, the first connecting shaft 52, the first universal shaft joint 53, the second connecting shaft 54, and the second universal shaft joint 55. Is.

  The control unit 61 receives detection signals from a resolver 104 (not shown) in the steering angle sensor 23, the motor rotation angle sensor 25, the turning torque sensor 32, and the turning power motor 45, and detects the vehicle speed. Receiving detection signals from the sensor 62, the yaw rate sensor 63 for detecting the yaw angular velocity (the angular velocity of the yaw motion), the acceleration sensor 64 for detecting the acceleration of the vehicle, and other various sensors 65, the reaction force motor 24, the turning power motor are received. 45 and a control signal to the clutch mechanism 51.

  That is, the control unit 61 automatically sets the steering reaction force according to the operation of the steering wheel 21 by controlling the reaction force motor 24, adds the steering reaction force to the steering wheel 21, and Control can be performed as in 1) to (4).

  (1) When the worm wheel 28 is rotated by the reaction force motor 24 in the direction opposite to the steering direction of the steering wheel 21, the steering force of the steering wheel 21 is canceled by the steering reaction force of the reaction force motor 24. work. For this reason, when the steering wheel 21 is steered, a steering force that is larger by the steering reaction force is required.

  (2) When the worm wheel 28 is rotated in the same direction as the steering direction of the steering wheel 21 by the reaction force motor 24, the action of adding the steering reaction force of the reaction force motor 24 to the steering force of the steering wheel 21 works. . For this reason, when the steering wheel 21 is steered, a steering force that is as small as the steering reaction force is sufficient.

  (3) When the steering wheel 21 is held at an arbitrary angle in a stopped state, the worm wheel 28 is adjusted while adjusting the steering reaction force of the reaction force motor 24 in the direction opposite to the rotation direction of the steering wheel 21 until then. A holding force is generated by rotating the.

  (4) When the steering wheel 21 is subsequently returned, a return force (steering reaction force) corresponding to so-called self-aligning torque that automatically returns the steering wheel 21 to the neutral position of the steering wheel 21 is a reaction force motor. 24 is transmitted to the worm wheel 28.

  Further, the control unit 61 automatically sets the characteristics of the angle ratio of the steered wheels 35 and 35 to the steering angle of the steering wheel 21, that is, the steering characteristics, by controlling the steered power motor 45. can do. That is, since the steering mechanism 30 is mechanically separated from the steering wheel 21 as described above, the correspondence between the steering angle of the steering wheel 21 and the operation amount of the steering actuator 38 is not subject to mechanical restrictions. Can be set. As a result, the steering characteristics can be flexibly set according to the traveling state of the vehicle, such as the vehicle speed, the degree of turning of the vehicle, and the presence or absence of acceleration / deceleration. Accordingly, the degree of freedom in designing the vehicle steering apparatus 10 can be increased.

  Further, in the vehicle steering apparatus 10, the steering shaft 22 of the steering mechanism 20 and the input shaft 31 of the steering mechanism 30 include a clutch mechanism 51, a first connecting shaft 52, a first universal shaft joint 53, and a second connecting shaft. 54 and the second universal shaft joint 55 are connected.

<Configuration and processing operation of tire angle detection block>
Next, the configuration and processing operation of the tire angle detection block will be described with reference to FIGS. The configuration and processing operation of the tire angle detection block will be described separately for tire angle detection when the vehicle is traveling and tire angle detection when the steering wheel is stationary.

<Functional blocks and processing operations for tire angle detection during vehicle travel>
As shown in FIG. 2, the functional block for detecting the tire angle when the vehicle travels includes a yaw rate sensor 63, a tire angle estimation unit 102, a tire angle detection unit 103, and a resolver 104. The tire angle estimation unit 102 and the tire angle detection unit 103 are configured in the control unit 61.

  Here, the tire angle estimation unit 102 estimates the tire angle based on the yaw rate of the yaw rate sensor 63. Specifically, the tire angle may be calculated using a relational expression between the yaw rate and the tire angle, or the relationship between the yaw rate and the tire angle is developed on a data table in advance, and based on this data table. The tire angle may be calculated.

  The tire angle detection unit 103 corrects the tire angle estimated by the tire angle estimation unit 102 with an output signal from the resolver 104 having a high detection resolution, and detects a highly accurate tire angle.

  Specifically, as shown in FIG. 3, first, the tire angle estimation unit 102 estimates the tire angle from the yaw rate of the yaw rate sensor 63, and outputs the estimation result to the tire angle detection unit 103 (step S101). An output signal from the resolver 104 is also input to the tire angle detection unit 103, and the estimated value of the tire angle in the tire angle estimation unit 102 is corrected by the output signal from the resolver 104 (step S102) to determine the tire angle. (Step S103).

  Therefore, in the above-described embodiment, a rough tire angle is calculated from the yaw rate of the vehicle, and the calculated tire angle is corrected by an output signal of a resolver having a high detection resolution, thereby detecting a highly accurate tire angle. Can do.

<Functional blocks and processing for tire angle detection during steering wheel suspension>
As shown in FIG. 4, the functional block for detecting the tire angle when the steering wheel is stationary includes a stroke end detection unit 201, a maximum tire angle estimation unit 202, a comparison unit 204, a maximum tire angle determination unit 205, The resolver 104, the tire angle detection unit 207, and the yaw rate sensor 63 are configured. The stroke end detection unit 201, the maximum tire angle estimation unit 202, the comparison unit 204, the maximum tire angle determination unit 205, and the tire angle detection unit 207 are configured in the control unit 61.

  Here, the stroke end detection unit 201 monitors the amount of change in the output signal from the resolver 104 in the stationary steering of the steering wheel in the stop state immediately after the start of the SWB system, and the amount of change in the output signal becomes substantially zero. When the stroke ends, the stroke end is detected.

  The maximum tire angle estimation unit 202 estimates that the tire angle is maximum when the stroke end detection unit 201 detects the stroke end. The comparison unit 204 compares the maximum tire angle estimated by the maximum tire angle estimation unit 202 with the yaw rate obtained from the yaw rate sensor 63 immediately after the vehicle travels, and outputs the comparison result to the maximum tire angle determination unit 205.

  The maximum tire angle determination unit 205 determines that the tire angle estimated by the maximum tire angle estimation unit 202 is the maximum tire angle when the comparison result by the comparison unit 204 substantially matches, and determines the maximum tire angle to the tire angle detection unit 207. Output.

  When the maximum tire angle is input from the maximum tire angle determination unit 205, the tire angle detection unit 207 performs correction based on the signal from the resolver 104 with reference to this angle, and detects the tire angle. On the other hand, when the maximum tire angle is not input from the maximum tire angle determination unit 205, the tire angle is estimated from the yaw rate of the yaw rate sensor 63, and the estimated tire angle is corrected by the value of the resolver 104 to detect the tire angle. .

  Specifically, as shown in FIG. 5, first, the stroke end detection unit 201 monitors the amount of change in the output signal from the resolver 104 in steering steering of the steering wheel in the stop state immediately after the start of the SWB system. When the change amount of the output signal becomes substantially zero, the stroke end is detected. When the stroke end detection unit 201 detects the stroke end, the maximum tire angle estimation unit 202 estimates that the tire angle is the maximum (step S201).

  Next, after the vehicle travels, the comparison unit 204 compares the maximum tire angle estimated by the maximum tire angle estimation unit 202 with the yaw rate from the yaw sensor 63 (step S202), and as a result of the comparison, the two substantially match. (“Yes” in step S203), the maximum tire angle determination unit 205 determines the maximum tire angle (step S204), and the tire angle detection unit 207 determines the output value of the resolver 104 based on the determined maximum tire angle. The tire angle is detected (step S205), and the tire angle is determined (step S208).

  On the other hand, if they do not match as a result of comparison (“No” in step S203), the tire angle detection unit 207 estimates the tire angle from the yaw rate of the yaw rate sensor 63 (step S206), and the tire value is determined based on the value of the resolver 104. The estimated angle value is corrected (step S207), and the tire angle is determined (step S208).

  Therefore, according to the above embodiment, if the tire angle calculated from the yaw rate of the vehicle and the estimated maximum tire angle substantially coincide with each other after the vehicle travels, the resolver value is determined based on the estimated maximum tire angle. The tire angle is detected by performing correction. On the other hand, when the estimated maximum tire angle and the tire angle estimated from the yaw rate do not substantially coincide with each other, it is determined that the stroke end has not been accurately detected, and the tire angle estimated from the yaw rate is corrected by the resolver value. Detect the angle. As a result, the tire angle can be accurately detected without using a sensor for detecting the tire angle.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes a design and the like within a scope not departing from the gist of the present invention.

It is a lineblock diagram of the steering device for vehicles concerning this embodiment. It is a block diagram concerning tire angle detection in this embodiment. It is a processing flow concerning tire angle detection in this embodiment. It is a block diagram concerning tire angle detection in this embodiment. It is a processing flow concerning tire angle detection concerning a conventional example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Vehicle steering device, 21 ... Steering wheel, 23 ... Steering angle sensor, 24 ... Reaction force motor, 38 ... Steering actuator, 63 ... Yaw rate sensor, 102 .. Tire angle estimation unit, 103... Tire angle detection unit, 104... Resolver, 201... Stroke end detection unit, 202... Maximum tire angle estimation unit, 204. ..Maximum tire angle determination unit, 207 ... Tire angle detection unit

Claims (3)

With the mechanical connection between the steering wheel and the steering gear box disconnected, the operation amount of the steering wheel is converted into an electrical signal, and the steering motor provided in the steering gear box is driven based on the electrical signal to rotate the wheel. In a steering apparatus for a vehicle that steers and applies a steering reaction force to the steering wheel by driving a steering reaction force motor connected to the steering wheel according to the operation amount.
Tire angle estimating means for estimating the tire angle from the yaw rate of the vehicle detected by the yaw sensor when the vehicle is running;
Tire angle detection means for detecting the tire angle by correcting the estimated tire angle with the value of the rotation angle sensor of the steering motor;
A vehicle steering apparatus comprising: With the mechanical connection between the steering wheel and the steering gear box disconnected, the operation amount of the steering wheel is converted into an electrical signal, and the steering motor provided in the steering gear box is driven based on the electrical signal to rotate the wheel. In a steering apparatus for a vehicle that steers and applies a steering reaction force to the steering wheel by driving a steering reaction force motor connected to the steering wheel according to the operation amount.
Stroke end detection means for detecting the stroke end of the steering gear box from the output change amount of the rotation angle sensor of the steering motor when the vehicle stops.
Maximum tire angle estimating means for estimating the tire angle at the end of the stroke as the maximum tire angle;
After the vehicle travels, when the estimated maximum tire angle and the tire angle estimated from the yaw rate of the vehicle substantially coincide with each other, the maximum tire angle is determined, and the steering motor is determined based on the determined maximum tire angle. Tire angle detection means for detecting the tire angle based on the output value of the rotation angle sensor of,
A vehicle steering apparatus comprising:   The tire angle detection means estimates the tire angle from the yaw rate when the estimated maximum tire angle and the tire angle estimated from the yaw rate of the vehicle do not substantially coincide with each other after the vehicle travels. The vehicle steering apparatus according to claim 2, wherein the tire angle is detected by correcting the tire angle with an output value of a rotation angle sensor of the steering motor.

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