JP2007062466A - Steering shaft rotation abnormality range determination device for vehicle and steering shaft rotation abnormality range determination method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steering shaft rotation abnormality range determination device for a vehicle and a steering shaft rotation abnormality determination method capable of determining whether or not abnormality on a steering shaft is generated in a range between an actuator position and a steering shaft rotation angle detection means position. <P>SOLUTION: The vehicle is provided with a steering angle sensor 2 for detecting a rotation angle of the steering shaft for connecting a steering wheel 1 and front wheels 9, 9; and a turning motor 6 for giving rotation torque making an actual turning angle and an instruction turning angle coincident. The vehicle is provided with a rotation abnormality range determination means (step S4, step S6 and step S7) for determining a rotation abnormality range of the steering shaft based on a current value of the turning motor 6 and an error of a value obtained by converting a turning motor rotation angle to an equivalent reaction force motor and a reaction force motor rotation angle when the steering shaft is rotated by the turning motor 6. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention belongs to the technical field of a steering shaft rotation abnormality range determination device and a steering shaft rotation abnormality range determination method for a vehicle provided with an actuator that applies rotational torque to a steering shaft.

  In a so-called steer-by-wire (SBW) system that breaks the mechanical connection between the steering wheel and the steered wheel and configures part of the steering transmission system with an electrical path, it can fail when an abnormality occurs. Safe measures are important. For example, when an abnormality is detected in the reaction force actuator, the reaction force control by the reaction force control unit is stopped, a mechanical backup mechanism that mechanically connects the steering wheel and the steering wheel is operated, and the steering control unit is steered. A configuration has been proposed in which the function as a normal electric power steering (EPS) device is realized by switching to the control for the above and controlling the steering actuator (see Patent Document 1). In a configuration having such a mechanical backup mechanism, it is necessary for the mechanical backup mechanism to operate reliably for safety and performance, and it is considered important to detect an abnormality including the mechanical backup mechanism.

In the control of the SBW system, for example, a feedback control system based on proportional / integral (PI) control is configured to compensate for a steady deviation and a phase delay that occur between the target turning angle and the actual turning angle. Is known (see Patent Document 2). In this way, by configuring a so-called angle servo system, it is possible to perform control that is highly resistant to the influence of disturbances, that is, control in which the target turning angle and the actual turning angle always coincide.
Japanese Patent Application Laid-Open No. 2004-090783 JP 2002-337711 A

  However, when such a control system is configured, since the disturbance suppression effect is strong, for example, when an abnormality that allows the steering itself, such as increased friction, occurs in the mechanical backup mechanism or the steering actuator of the SBW system, It is assumed that the operation is the same as when no occurrence occurs. This is because the feedback control absorbs the disturbance due to the abnormality, and no change appears in the actual turning.

  Under such circumstances, not only does the driver not notice abnormalities, but also during periodic inspections at dealers etc., it is difficult to find abnormalities by visual inspection, so abnormalities have progressed to a state where the angle servo system can not cope. Abnormalities will be discovered for the first time. Here, a method of detecting a system abnormality based on the current value of the servo system during traveling is also conceivable, but the current for constantly detecting and suppressing changes in road surface conditions as a disturbance changes during the traveling. In addition, since the angle command value also changes depending on the running conditions, there is a problem that it is difficult to distinguish and detect current changes due to system abnormalities.

  The present invention has been made paying attention to the above-mentioned problem, and the object of the present invention is to determine whether or not an abnormality on the steering shaft has occurred in the range between the actuator position and the steering shaft rotation angle detection means position. The present invention provides a steering shaft rotation abnormality range determination device and a steering shaft rotation abnormality determination method for a vehicle.

In order to achieve the above-mentioned object, in the steering shaft rotation abnormality determination method of the present invention,
Steering shaft rotation angle detecting means for detecting the rotation angle of the steering shaft connecting the steering wheel and the steered wheel, and an actuator for applying to the steering shaft a rotational torque that matches the rotation angle of the steering shaft with the target rotation angle. In the equipped vehicle,
An abnormal rotation range of the steering shaft is determined based on a current value of the actuator and a deviation between a rotation angle of the steering shaft and a rotation angle of the actuator when the steering shaft is rotated by the actuator. It is characterized by that.

  In the present invention, the rotation abnormality range of the steering shaft is determined based on the current value of the actuator and the deviation between the rotation angle of the steering shaft and the rotation angle of the actuator when the steering shaft is rotated by the actuator. Is done. That is, in the angle servo system that matches the rotation angle of the steering shaft with the target rotation angle, when the current value of the actuator is higher than the assumed current value by a predetermined value or more, it can be determined that there is a rotation abnormality of the steering shaft. By determining the deviation between the rotation angle of the steering shaft and the rotation angle of the actuator, it is determined whether or not the abnormality has occurred in the range between the actuator position and the steering shaft rotation angle detection means position. Can do. For example, when the deviation between the rotation angle of the steering shaft and the rotation angle of the actuator is small, there is an abnormality (for example, increased friction) in a portion other than between the actuator position on the steering shaft and the steering shaft rotation angle detection means position. It can be judged that it has occurred. On the other hand, when the deviation between the rotation angle of the steering angle and the rotation angle of the actuator is large, it can be determined that an abnormality has occurred in the range between the actuator position on the steering shaft and the steering shaft rotation angle detection means position. . As a result, it can be determined whether or not an abnormality on the steering shaft has occurred in a range between the actuator position and the steering shaft rotation angle detection means position.

  Hereinafter, the best mode for carrying out the steering shaft rotation abnormality range determination device and the steering shaft rotation abnormality determination method of the present invention will be described based on Examples 1 and 2.

First, the configuration will be described.
FIG. 1 is an overall configuration diagram of a steer-by-wire (SBW) system to which a steering shaft rotation abnormality range determination device for a vehicle according to a first embodiment is applied.

  The SBW system according to the first embodiment includes a handle 1, a steering angle sensor (steering shaft rotation angle detecting means) 2, a reaction force motor 3, a backup mechanism connecting / disconnecting clutch (hereinafter referred to as a clutch) 4, and a backup cable 5. A steering motor (actuator) 6, a steering angle sensor 7, a steering mechanism 8, front wheels (steering wheels) 9 and 9, a reaction force controller 10, a steering controller 11, and a communication line 12 It is equipped with.

  The SBW system according to the first embodiment includes a handle 1, a reaction force motor 3, and the like by a clutch 4, and includes a steering unit that applies a steering reaction force to the handle 1, a steering mechanism 8, a steering motor 6, and the like. Accordingly, the steered portion that steers the front wheels 9 and 9 is mechanically separated, but the steering portion and the steered portion can be mechanically connected by fastening the clutch 4. In the first embodiment, the steering torque transmission path from the handle 1 to the front wheels 9 and 9 when the clutch 4 is engaged and the steering unit and the steered unit are mechanically connected via the backup cable 5 is defined as a steering shaft. Will be described.

  The steering angle sensor 2 detects the rotation operation of the steering wheel 1, the steering controller 11 calculates the drive command value of the steering motor 6, and the steering mechanism 8 is driven by the driving of the steering motor 6. , 9 are steered. The steered motor 6 is composed of a brushless motor or the like. The reaction force motor 3 for applying a steering reaction force to the handle 1 is composed of a brushless motor or the like, similar to the steering motor 6, and is driven based on a drive command value calculated by the reaction force controller 10. The The drive command value calculated by the reaction force controller 10 and the turning controller 11 is a current command value to the reaction force motor 3 and the turning motor 6.

  The current command value calculated by the turning controller 11 is calculated by an angle servo system that performs control calculation so that the actual turning angle coincides with the command turning angle (target rotation angle). The angle servo system is configured using, for example, a robust model matching method as shown in FIG. This method includes a model matching compensator 11a and a robust compensator 11b, and the robust compensator 11b calculates a compensation current according to a disturbance component, so that the actual turning angle is commanded even when a disturbance occurs. It is a control system with excellent durability that can be brought close to a corner.

Next, the operation will be described.
[Abnormal diagnosis control processing]
FIG. 3 is a flowchart showing a diagnostic method of the SBW system using the angle servo system of the first embodiment, and each step will be described below. This diagnosis is based on the premise that the diagnosis is performed at a stop in a place with dedicated equipment, such as periodic inspection at a dealer or inspection at the time of production at a factory. Further, in the first embodiment, a description will be given of an operation in a case where a steering operation is performed by the steering motor 6 and a torque in a direction opposite to the rotation direction is generated by the reaction motor 3.

  In step S1, the vehicle is jacked up as a diagnostic preparation, and the front wheels 9, 9 are lifted off the road surface. This is because the front wheels 9 and 9 are actually steered at the time of diagnosis, so that the influence of fluctuations in the friction coefficient between the road surface and the tire is eliminated. By jacking up, it is possible to eliminate the effects of road surface conditions (asphalt pavement, concrete, oil-resistant paint floor, etc.) at the diagnosis location, tire wear, and replacement with tires of different sizes and performance. A device such as a turntable in which the load during the turning operation of the front wheels 9, 9 is always constant may be used.

  In step S2, a turning angle command value of a turning pattern set in advance is given to the turning controller 11. Based on the turning angle command value, the current command value of the turning motor 6 is calculated. Here, the turning motor rotation angle is mechanically determined by the gear ratio of the steering mechanism 8. For example, if the gear ratio between the steering motor 6 and the pinion gear is 10, and the gear ratio between the pinion rotation angle (= the rotation angle of the handle 1) and the steering angle is 15, The rudder motor rotation angle will move 750 °.

  Further, in order to apply an appropriate load to the backup cable 5, a current command value is generated by the reaction force controller 10 so that a constant torque in the direction opposite to the rotation direction is generated in the reaction force motor 3. The magnitude of the torque at this time is based on a value corresponding to the maximum steering torque when a general power assist is operating.

  In such a state, a turning operation is performed based on the turning pattern, and the turning motor current during this time (the current command value of the turning motor 6 and the actual current substantially coincide) and the turning motor rotation angle. The reaction force motor rotation angle is measured.

  In step S3, it is confirmed whether or not the steering motor current is normal. The range of the normal current value (assumed current value) when moving in the steering pattern is set in advance, and it is confirmed whether or not the value measured this time is within the range of the normal current value. If the steered motor current is within the set range, it is determined that the steered motor current is normal, and the process proceeds to step S4. If the steered motor current exceeds the set range, the steered motor current is determined to be abnormal, and the process proceeds to step S5. .

  In step S4, since it is determined that the steering motor current is normal, it is determined that no abnormality has occurred in the SBW system, and the diagnosis is terminated.

  In step S5, it is confirmed whether or not the reaction force motor rotation angle is normal. Under normal conditions, the reaction force motor 3 follows the rotation of the steering motor 6 with a backlash of the clutch 4 and a backlash of the backup cable 5 and a slack. Assuming that the reaction motor rotation angle coincides with the rotation angle of the handle 1 (= pinion gear rotation angle) (gear ratio = 1), when the gear ratio between the steering motor 6 and the pinion gear is 10, the steering motor When 6 rotates 10 times, the reaction force motor 3 rotates once. Determine the error between the value obtained by converting the turning motor rotation angle to the reaction force motor equivalent (1/10 in this case) and the reaction force motor rotation angle, and whether the value is within the preset range in consideration of the above play. Confirm whether or not. If the error is within the set range, it is determined that the reaction force motor rotation angle is normal, and the process proceeds to step S6. If the error exceeds the set range, the reaction force motor rotation angle is determined to be abnormal, and the process proceeds to step S7. .

  In step S6, since it is determined that the steering motor current is abnormal and the reaction force motor rotation angle is normal, a failure B is diagnosed. The failure B is an abnormality in a portion other than between the steering motor 6 and the reaction force motor 3.

  In step S7, since it is determined that the steering motor current is abnormal and the reaction force motor rotation angle is also abnormal, a failure A is diagnosed. The failure A is an abnormality between the steering motor 6 and the reaction force motor 3.

  Rotation abnormality range determination for determining the rotation abnormality range of the steering shaft based on the current value of the actuator (steering motor 6) and the deviation between the rotation angle of the steering shaft and the rotation angle of the actuator in steps S1 to S7. Means are configured.

[Abnormal diagnosis control operation]
When the steering shaft is rotated by the steered motor 6 and friction is generated in a state where the rotational relationship between the steered side and the steered side does not match, step S1 → step in the flowchart of FIG. The flow proceeds from S2 to step S3 to step S5 to step S7. In step S7, it is determined that friction has occurred between the steering motor 6 and the reaction force motor 3.

  In the SBW system according to the first embodiment, even when friction is generated in any part, the turning motor current is increased by the angle servo control, so that the turning motor rotation angle moves according to the command value. At this time, if there is an abnormality such as a hooking of the backup cable 5 between the steering motor 6 and the reaction force motor 3, the reaction force motor rotation angle is a value determined based on the turning motor rotation angle (gear ratio of both motors). Does not match the angle after conversion. Therefore, when the relationship between the turning angle of the steering side and the turning angle of the steering side does not match and the turning motor current exceeds the preset current normal range of the system, It can be determined that an abnormality (increased friction) has occurred between the force motors 3.

  Further, when the steering shaft is rotated by the steered motor 6 and the friction is generated when the rotational relationship between the steered side and the steered side is coincident, step S1 → The flow proceeds from step S2 to step S3 to step S5 to step S6. In step S6, it is determined that friction has occurred in a portion other than between the steered motor 6 and the reaction force motor 3.

  If there is no abnormality between the steered motor 6 and the reaction force motor 3, the reaction force motor rotation angle coincides with a value determined based on the steered motor rotation angle (angle after the gear ratio conversion of both motors). Therefore, when the relationship between the turning angle on the steering side and the turning angle on the steering side coincides and the turning motor 6 exceeds the preset current normal range of the system, the turning motor 6 and the reaction force It can be determined that an abnormality (increased friction) has occurred in a portion other than between the motors 3.

  As described above, the steering operation is performed with the steering pattern preset by the steering controller 11, and the abnormality of the SBW system is determined by measuring the steering motor current, the reaction force motor rotation angle, and the steering motor rotation angle. can do. Also, depending on the state of the steering motor current and the reaction force motor rotation angle, the range of the abnormal part of whether the abnormal part of the SBW system is between the steering motor 6 and the reaction force motor 3 or other part. Can be specified.

[Abnormal diagnosis]
(Normal)
Based on the time chart shown in FIG. 4, the diagnosis operation will be described in time series.
First, a turning angle command value from 0 to θ1 is output from time t1 to time t2. A sufficiently long time (for example, 1 minute) is set between the time point t1 and the time point t2. This is to eliminate the influence of the inertia component and damping component of the SBW system and to enable reliable abnormality detection. At this time, a current command value that gives a constant torque in the direction opposite to the rotation direction is given to the reaction force motor 3.

  From time t2 to time t3, the turning angle command value is held at θ1. This is a measure for suppressing a change in the steering motor current value immediately after starting a turning operation in the opposite direction. At this time, the current command value to the reaction force motor 3 is set to zero.

  Next, a turning angle command value from θ1 to θ2 is output from time t3 to time t4. Here, as in the period from the time point t1 to the time point t2, a sufficiently long time (for example, 2 minutes) is set.

  From time point t4 to time point t5, the turning angle command value is held at θ2 as in the case of time point t2 to time point t3.

  Next, a turning angle command value from θ2 to 0 is output from time t5 to time t6. Here, as in the period from the time point t1 to the time point t2, a sufficiently long time (for example, 1 minute) is set.

  The steering motor current value between time t1 to time t2, time t3 to time t4, and time t5 to time t6 is set to a normal current value set in advance. It is confirmed whether it is within the range (hatched portion in FIG. 4). At the same time, the value obtained by converting the turning motor rotation angle to the reaction force motor and the error of the reaction force motor rotation angle (the reaction motor equivalent conversion value of the turning motor rotation angle minus the reaction force motor rotation angle) are obtained and the value obtained. Is within a preset range (hatched portion in FIG. 4).

  The time chart of FIG. 4 shows a case where the SBW system is operating normally without any abnormality, that is, a case where the steering motor current value and the converted angle error are within the set range.

  If θ1 is equivalent to full right steering and θ2 is equivalent to full left steering, partial damage to the actuator (such as missing gears) and partial damage to the backup mechanism (such as hooking due to frayed backup cable) will operate. It can be detected anywhere in the entire range.

  In addition, if the increase in friction that occurs regularly (rubbing between the inner and outer cables of the backup cable, eccentricity of the cable pulley, etc.) is detected, there is no need to turn left and right, and θ1 and θ2 are components. Abnormality can be detected by setting the angle to be greater than or equal to the angle change that can occur due to the state change due to the backlash or deterioration with time. θ1 and θ2 may be set according to the purpose of diagnosis.

(When a partial abnormality occurs between the steering motor 6 and the reaction force motor 3)
Next, a diagnostic operation when an abnormality occurs between the steering motor 6 and the reaction force motor 3 (for example, the backup cable 5) will be described based on the time chart shown in FIG.

  FIG. 5 shows each waveform when an abnormality occurs at time te when operating in accordance with the turning angle command value from 0 to θ1 as in FIG. If it is detected that the cable is caught at time te, a large current flows through the steered motor 6 so as to maintain the steered angle. Since this current increase exceeds a preset normal current value range (hatched portion), it is determined that the steering motor current is abnormal. Furthermore, since the reaction force motor rotation angle does not move as much as the cable is hooked after time te, the conversion angle error increases. Since this conversion angle error exceeds a preset range (hatched portion), it is determined that the reaction force motor rotation angle is abnormal. Since the steering motor current is abnormal and the reaction force motor rotation angle is abnormal, it is determined that an abnormality has occurred between the steering motor 6 and the reaction force motor 3.

(When a steady abnormality occurs between the steering motor 6 and the reaction force motor 3)
FIG. 6 shows a case where an abnormality has occurred between the steering motor 6 and the reaction force motor 3 (for example, the backup cable 5), as in FIG. ing. In the friction increase that occurs regularly, the steering motor current required for the steering operation increases throughout the entire steering pattern. Further, since the reaction force motor 3 is also difficult to rotate due to the effect of increased friction, the conversion angle error increases. As a result, as in FIG. 5, the steering motor current abnormality and the reaction force motor rotation angle abnormality occur, and it is diagnosed that an abnormality has occurred between the steering motor 6 and the reaction force motor 3.

(When a partial abnormality occurs in a part other than between the steering motor 6 and the reaction force motor 3)
Next, based on the time chart shown in FIG. 7, a diagnostic operation when an abnormality has occurred in a portion (for example, rack gear) other than between the steering motor 6 and the reaction force motor 3 will be described.

  FIG. 7 shows each waveform when an abnormality occurs at time te when operating according to the turning angle command value from 0 to θ1 as in FIG. 4. If an abnormality of the rack gear is detected at time te, a large current flows to the steered motor 6 so as to maintain the steered angle. Since this current increase exceeds a preset normal current value range (hatched portion), it is determined that the steering motor current is abnormal. At this time, since there is no abnormality between the steering motor 6 and the reaction force motor 3, the reaction force motor 3 normally follows the movement of the steering motor 6. Therefore, since the conversion angle error does not exceed a preset range (hatched portion), it is determined that the reaction force motor rotation angle is normal. Since the steering motor current is abnormal and the reaction force motor rotation angle is normal, it is determined that an abnormality has occurred in a portion other than between the steering motor 6 and the reaction force motor 3.

(When a steady abnormality occurs in a portion other than between the steering motor 6 and the reaction force motor 3)
FIG. 8 shows a case where an abnormality has occurred in a portion (for example, a rack gear) other than between the steering motor 6 and the reaction force motor 3 as in FIG. 7, but an abnormality in which friction constantly increases. Is shown. In the friction increase that occurs regularly, the steering motor current required for the steering operation increases throughout the entire steering pattern. At this time, since there is no abnormality between the turning motor 6 and the reaction force motor 3, the reaction force motor 3 normally follows the movement of the turning motor 6. As a result, as in FIG. 7, the steering motor current is abnormal and the reaction force motor rotation angle is normal, and it is determined that an abnormality has occurred in a portion other than between the steering motor 6 and the reaction force motor 3.

[SBW system rotation abnormality diagnosis]
In the first embodiment, when the turning motor 6 that performs angle servo control is rotated within a predetermined angle range, the occurrence of friction is determined from the detected current value of the rotated steering motor 6 and each rotation angle. In the SBW system, even if friction has occurred due to an abnormality in some part, the turning motor current or reaction force motor current is increased by the angle servo control. It is possible to move according to the command value. If there is no abnormality between the steering motor 6 and the reaction force motor 3, the other motor rotates in accordance with the rotation of one motor, and the rotational relationship between the two motors coincides. In this case, it can be determined that an abnormality (increased friction) has occurred in a portion other than between the steering motor 6 and the reaction force motor 3. When friction is generated between the turning motor 6 and the reaction force motor 3, the turning motor current or the reaction force motor current is increased by the angle servo control. In this case, since the rotational relationship between the motors 3 and 6 does not match, it can be determined that an abnormality (increased friction) has occurred between the steering motor 6 and the reaction force motor 3. As described above, the abnormality of the SBW system can be detected based on the motor current value for performing the angle servo control and the rotation angle of the motor.

[Riding motor drive load imparting action by reaction force motor]
In the first embodiment, when the steering shaft is rotated by the steering motor 6, the reaction force motor 3 applies torque in the direction opposite to the rotation direction. When rotating by the reaction force motor 3, a portion (gear and tire around the rack shaft) ahead of the steering motor 6 is loaded between the steering motor 6 and the reaction force motor 3, so that abnormality detection is possible. A necessary moderate load is applied, but when rotating by the steering motor 6, the portion ahead of the reaction force motor 3 (the handle 1) becomes a load, and therefore the steering shaft between the steering motor 6 and the reaction force motor 3. In addition, an appropriate load necessary for detecting an abnormality is not applied. Therefore, by adding a torque in the direction opposite to the rotation direction to the reaction force motor 3 and applying an appropriate load (equivalent to the maximum steering torque of EPS), it is possible to detect an abnormality as in the case where the reaction force motor 3 is rotated. Become.

[Steering axis rotation range setting action]
In the first embodiment, the predetermined angle range in which the steered motor 6 is rotated is set to be equal to or greater than an angle change that can be caused by a change in state due to rattling or deterioration over time so that the steering shaft is rotated. By making a diagnosis by rotating the component up to an angle greater than an angle change that can occur due to a change in state due to play or deterioration with time, an increase in the friction that is constantly generated can be detected. That is, when the rotation is performed within the range of backlash, an angular difference between the steered motor 6 and the reaction force motor 3 may be generated. Is this difference caused by abnormality or whether it is caused by backlash? Is difficult to distinguish.

  In the first embodiment, the predetermined angle range in which the steering shaft is rotated is the left and right rack end range during full left and right steering. For example, partial breakage of the mechanical backup mechanism (clutch 4 or backup cable 5) such as partial breakage of the actuator such as gear breakage or hooking due to fraying of the backup cable 5 occurred anywhere in the operating range. Even if it can be detected. That is, unlike abnormalities such as increased friction that occur regularly, partial abnormalities need to be confirmed in the entire operable region. By turning left and right fully, it is possible to identify where an abnormality has occurred in the operating range.

[Steering angle rotation speed setting action]
In the first embodiment, when the steered motor 6 is rotated within a predetermined angle range, the rotation speed is set to a predetermined speed or less. By moving at a sufficiently low predetermined speed or less, the influence of inertia components and damping components can be prevented, and more reliable abnormality detection becomes possible.

Next, the effect will be described.
In the vehicle steering shaft rotation abnormality range determination device according to the first embodiment, the effects listed below can be obtained.

  (1) A steering angle sensor 2 that detects a rotation angle of a steering shaft that connects the steering wheel 1 and the front wheels 9 and 9, a steering motor 6 that applies a rotational torque that makes the actual turning angle coincide with the command turning angle, When the steering shaft is rotated by the steered motor 6, the current value of the steered motor 6, the value obtained by converting the steered motor rotation angle to the reaction force motor, and the reaction force motor rotation angle And a rotation abnormality range determination means (steps S1 to S7) for determining a rotation abnormality range of the steering shaft based on the error. Therefore, it can be determined whether or not an abnormality on the steering shaft has occurred between the steering motor 6 and the reaction force motor 3.

  (2) The rotation abnormality range determination means determines that there is a rotation abnormality of the steering shaft when the current value of the steering motor 6 is higher than the assumed current value (normal current value) by a predetermined value or more. An abnormal rotation can be accurately detected.

  (3) Since the rotation abnormality range determination means determines that there is a rotation abnormality between the steering motor 6 and the reaction force motor 3 when the error is equal to or greater than a predetermined value, it occurs between the steering motor 6 and the reaction force motor 3. Rotation abnormality such as increased friction can be accurately detected.

  (4) A steering unit that includes the steering angle sensor 2 and applies a steering reaction force to the steering wheel 1, a steering unit that includes the steering motor 6 and steers the front wheels 9 and 9 according to the steering operation, The rotation abnormality range determining means includes a steering shaft that is rotated by the steering motor 6 of the steering section. Therefore, in the SBW system, it can be accurately determined whether or not an abnormality such as an increase in friction has occurred in the mechanical backup mechanism between the steering motor 6 and the reaction force motor 3.

  (5) Since the steering unit applies a predetermined torque in a direction opposite to the direction in which the reaction force motor 3 rotates the steering shaft, when the rotating shaft is rotated by the steering motor 6, an abnormal load is applied. Detection can be performed accurately.

  (6) The rotation abnormality range determining means rotates the steering shaft by the steered motor 6 so that the rotation is within a predetermined angle range where the steering shaft rotation angle is generated. Can be detected.

  (7) Since the rotation abnormality range determination means rotates the steering shaft to the left and right rack ends when the steering motor 6 is rotated, abnormality detection is possible in all the steering ranges.

  (8) The rotation abnormality range determination means sets the rotation speed to a predetermined speed or less when the steering motor 6 rotates the steering shaft. That is, by moving at a sufficiently slow speed, the influence of inertia components and damping components can be prevented, and more reliable abnormality detection becomes possible.

  The second embodiment is an example in which a rotation abnormality is determined by rotating the reaction force motor 3 in the SBW system. The configuration is the same as that of the first embodiment shown in FIG.

Next, the operation will be described.
[Abnormal diagnosis control processing]
FIG. 9 is a flowchart showing a diagnostic method of the SBW system using the angle servo system of the second embodiment, and each step will be described below. Note that step S11 is the same as step S1 in FIG.

  In step S12, a steering angle command value of a predetermined steering pattern is given to the reaction force controller 10. Based on this steering angle command value, the current command value of the reaction force motor (actuator) 3 is calculated. The reaction force motor 3 is coaxial with the handle 1, and the steering angle (handle angle) = the reaction force motor rotation angle. In the second embodiment, unlike the first embodiment, an appropriate load (gear and tire around the rack shaft) is applied to the backup cable 5, so that a constant torque in the direction opposite to the rotation direction is generated in the steering motor 6. There is no need to provide a current command value. In such a state, the steering operation is performed based on the steering pattern. During this period, the reaction force motor current (the current command value of the reaction force motor 3 and the actual current substantially coincide), the turning motor rotation angle, the reaction force Measure the motor rotation angle.

  In step S13, it is confirmed whether or not the reaction force motor current is normal. The range of the normal current value when moving in a predetermined steering pattern is set in advance, and it is confirmed whether or not the value measured this time is within the range of the normal current value. If the reaction force motor current is within the set range, it is determined that the reaction force motor current is normal, and the process proceeds to step S14. If it exceeds the set range, the reaction force motor current is determined to be abnormal, and the process proceeds to step S15.

  In step S14, since it is determined that the reaction force motor current is normal, it is determined that no abnormality has occurred in the SBW system, and the diagnosis is terminated.

  In step S15, it is confirmed whether or not the turning motor rotation angle is normal. Under normal conditions, the steered motor 6 follows the rotation of the reaction force motor 3 with a backlash of the clutch 4 and a backlash of the backup cable 5 and a slack. The reaction force motor rotation angle coincides with the rotation angle of the handle 1 (gear ratio = 1). Therefore, when the gear ratio between the steering motor 6 and the pinion gear is 10, when the reaction force motor 3 makes one rotation, the steering motor 6 will rotate 10 times. An error between a reaction force motor rotation angle and a value obtained by converting the turning motor rotation angle to a reaction force motor is obtained, and it is confirmed whether or not the value is within a preset range in consideration of the play. If the error is within the set range, it is determined that the turning motor rotation angle is normal, and the process proceeds to step S16. If the error exceeds the set range, the turning motor rotation angle is determined to be abnormal, and the process proceeds to step S17. .

  In step S16, since it is determined that the reaction motor current is abnormal and the turning motor rotation angle is normal, a failure B is diagnosed. The failure B is an abnormality in a portion other than between the steering motor 6 and the reaction force motor 3.

  In step S17, since it is determined that the reaction motor current is abnormal and the turning motor rotation angle is also abnormal, a failure A is diagnosed. The failure A is an abnormality between the steering motor 6 and the reaction force motor 3.

  Rotation abnormality range determination for determining the rotation abnormality range of the steering shaft based on the current value of the actuator (reaction force motor 3) and the deviation between the rotation angle of the steering shaft and the rotation angle of the actuator in steps S11 to S17. Means are configured.

[Abnormal diagnosis control operation]
When the steering shaft is rotated by the reaction force motor 3 and friction is generated in a state where the rotational relationship between the steered side and the steering side does not match, step S11 → step S12 in the flowchart of FIG. The flow proceeds from step S13 to step S15 to step S17. In step S17, it is determined that friction has occurred between the steered motor 6 and the reaction force motor 3.

  In the SBW system according to the second embodiment, even when friction occurs in any part, the reaction force motor rotation angle moves according to the command value by increasing the reaction force motor current by the angle servo control. At this time, if there is an abnormality such as a hooking of the backup cable 5 between the steering motor 6 and the reaction force motor 3, the rotation angle of the steering motor is determined based on the reaction motor rotation angle (the gear ratio of both motors). Does not match the angle after conversion. Accordingly, when the reaction force motor current exceeds the preset current normal range in a state where the relationship between the rotation angle on the steering side and the rotation angle on the steering side does not match, It can be determined that an abnormality (increased friction) has occurred between the force motors 3.

  Further, when the steering shaft is rotated by the reaction force motor 3 and the friction is generated in the state where the turning side and the steering side are in the same rotational relationship, step S11 → The flow proceeds from step S12 to step S13 to step S14 to step S15 to step S16. In step S16, it is determined that friction has occurred in a portion other than between the steered motor 6 and the reaction force motor 3.

  If there is no abnormality between the steered motor 6 and the reaction force motor 3, the steered motor rotation angle coincides with a value determined based on the reaction force motor rotation angle (angle after the gear ratio conversion of both motors). Therefore, when the relationship between the turning angle on the steering side and the turning angle on the steering side coincides and the reaction force motor 3 exceeds the preset current normal range of the system, the turning motor 6 and the reaction force It can be determined that an abnormality (increased friction) has occurred in a portion other than between the motors 3.

  As described above, the steering operation is performed with the steering pattern set in advance by the reaction force controller 10, and the abnormality of the SBW system is determined by measuring the reaction force motor current, the reaction force motor rotation angle, and the turning motor rotation angle. Can do. In addition, the abnormal part of the SBW system can be specified between the steering motor 6 and the reaction force motor 3 or any other part depending on the state of the reaction force motor current and the turning motor rotation angle.

[Abnormal diagnosis]
(Normal)
Next, the diagnosis operation will be described in time series based on the time chart shown in FIG.
First, a steering angle command value from 0 to θ1 is output from time t1 to time t2. A sufficiently long time (for example, 1 minute) is set between the time point t1 and the time point t2. This is to eliminate the influence of the inertia component and damping component of the SBW system and to enable reliable abnormality detection.

  From time t2 to time t3, the steering angle command value is held at θ1. This is a measure to suppress the fluctuation of the reaction force motor current value when the steering operation in the opposite direction is started immediately, and this is suppressed.

  Next, a steering angle command value from θ1 to θ2 is output from time t3 to time t4. Here, as in the period from time t2 to time t2, a sufficiently long time (for example, 2 minutes) is set.

  From the time point t4 to the time point t5, the steering angle command value is held at θ2, similarly to the time point t2 to the time point t3.

  Next, a steering angle command value from θ2 to 0 is output from time t5 to time t6. Here, as in the period from the time point t1 to the time point t2, a sufficiently long time (for example, 1 minute) is set.

  The reaction force motor current value between time t1 to time t2, time t3 to time t4, and time t5 to time t6 is within the preset normal current value range. Check whether it is (hatched part). At the same time, an error (reaction force motor rotation angle−reaction motor equivalent conversion value of the turning motor rotation angle) between the reaction force motor rotation angle and the value obtained by converting the turning motor rotation angle to the equivalent of the reaction force motor is obtained. Is within the preset range (hatched part).

  FIG. 10 shows a case where the SBW system is operating normally without any abnormality, that is, a case where the reaction force motor current value and the conversion angle error are within the set range. Note that the method for setting θ1 and θ2 is the same as that in the first embodiment, and thus the description thereof is omitted.

(When a partial abnormality occurs between the steering motor 6 and the reaction force motor 3)
Next, based on the time chart shown in FIG. 11, a diagnostic operation when an abnormality occurs between the steering motor 6 and the reaction force motor 3 (for example, the backup cable 5) will be described.

  FIG. 11 shows each waveform when an abnormality occurs at time te when operating according to the steering angle command value from 0 to θ1 as in FIG. If it is detected that the cable is caught at time te, a large current flows through the reaction force motor 3 so as to maintain the steering angle. Since this current increase exceeds a preset normal current value range (hatched portion), it is determined that the reaction force motor current is abnormal. Further, after the time point te, the turning motor rotation angle does not move as much as the cable is hooked, so that the conversion angle error increases. Since this conversion angle error exceeds a preset range (hatched portion), it is determined that the turning motor rotation angle is abnormal. Since the reaction force motor current is abnormal and the turning motor rotation angle is abnormal, it is determined that an abnormality has occurred between the turning motor 6 and the reaction force motor 3.

(When a partial abnormality occurs in a part other than between the steering motor 6 and the reaction force motor 3)
Next, a diagnostic operation when an abnormality has occurred in a portion (for example, a rack gear) other than between the steering motor 6 and the reaction force motor 3 will be described with reference to FIG.

  FIG. 12 shows each waveform when an abnormality occurs at the time point te when operating according to the steering angle command value from 0 to θ1, as in FIG. If an abnormality of the rack gear is detected at time te, a large current flows through the reaction force motor 3 so as to maintain the steering angle. Since this current increase exceeds a preset normal current value range (hatched portion), it is determined that the reaction force motor current is abnormal. At this time, since there is no abnormality between the steered motor 6 and the reaction force motor 3, the steered motor 6 normally follows the movement of the reaction force motor 3. Therefore, since the conversion angle error does not exceed a preset range (hatched portion), it is determined that the turning motor rotation angle is normal. Since the reaction force motor current is abnormal and the turning motor rotation angle is normal, it is determined that an abnormality has occurred in a portion other than between the turning motor 6 and the reaction force motor 3.

  Although the description is omitted in the second embodiment, the same diagnosis is possible even in an abnormality in which friction constantly increases as in the first embodiment.

Next, the effect will be described.
In the vehicle steering shaft rotation abnormal range determination device of the second embodiment, in addition to the effects (1) to (3) and (6) to (8) of the first embodiment, the following effects can be obtained.

  (9) A steering unit that includes the reaction force motor 3 and applies a steering reaction force to the steering wheel 1, a steering unit that includes the steering angle sensor 7 and steers the front wheels 9 and 9 according to the steering operation, The rotation abnormal range determination means (step S11 to step S17) rotates the steering shaft by the reaction force motor 3 of the steering section. Therefore, in the SBW system, it can be accurately determined whether or not an abnormality such as an increase in friction has occurred in the mechanical backup mechanism between the steering motor 6 and the reaction force motor 3.

(Other examples)
The best mode for carrying out the present invention has been described based on the first and second embodiments. However, the specific configuration of the present invention is not limited to the first and second embodiments. Design changes and the like within a range that does not depart from the gist are also included in the present invention.

  For example, in the first and second embodiments, the vehicle equipped with the SBW system has been described, but the present invention can also be applied to a vehicle equipped with an electric power steering (EPS) system. When the present invention is applied to the EPS system, the actuator is an assist motor for the EPS system, and the steering shaft rotation angle is the steering angle of the steering wheel.

1 is an overall configuration diagram of a steer-by-wire system to which a steering shaft rotation abnormality range determination device for a vehicle according to a first embodiment is applied. It is a control block diagram of the steering controller 11 using the robust model matching method of Example 1. 3 is a flowchart illustrating a diagnostic method for the SBW system using the angle servo system according to the first embodiment. It is a time chart (normal time) which shows a diagnostic operation at the time of giving an angle command to steering motor 6 of Example 1. FIG. It is a time chart (when a partial abnormality generate | occur | produces between the steering motor 6 and the reaction force motor 3) which shows the diagnostic operation | movement at the time of giving an angle command to the steering motor 6 of Example 1. FIG. It is a time chart which shows a diagnostic operation at the time of giving an angle command to steering motor 6 of Example 1 (when regular abnormality occurs between steering motor 6 and reaction force motor 3). It is a time chart (when a partial abnormality generate | occur | produces in parts other than between the steering motor 6 and the reaction force motor 3) which shows the diagnostic operation | movement at the time of giving an angle command to the steering motor 6 of Example 1. FIG. It is a time chart which shows a diagnostic operation at the time of giving an angle command to steering motor 6 of Example 1 (when a steady abnormality occurs in parts other than between steering motor 6 and reaction force motor 3). 6 is a flowchart illustrating a diagnostic method of the SBW system using the angle servo system according to the second embodiment. It is a time chart (normal time) which shows a diagnostic operation at the time of giving an angle command to reaction force motor 3 of Example 2. It is a time chart (when a partial abnormality generate | occur | produces between the steering motor 6 and the reaction force motor 3) which shows the diagnostic operation at the time of giving an angle command to the reaction force motor 3 of Example 2. FIG. It is a time chart (when a partial abnormality generate | occur | produces in parts other than between the steering motor 6 and the reaction force motor 3) which shows a diagnostic operation at the time of giving an angle command to the reaction force motor 3 of Example 2. FIG.

Explanation of symbols

1 Steering wheel 2 Steering angle sensor 3 Reaction force motor 4 Clutch 5 Backup cable 6 Steering motor 7 Steering angle sensor 8 Steering mechanism 9, 9 Front wheel 10 Reaction force controller 11 Steering controller 11a Model matching compensator 11b Robust compensator 12 Communication line

Claims (10)

Steering shaft rotation angle detecting means for detecting the rotation angle of the steering shaft connecting the steering wheel and the steered wheel, and an actuator for applying to the steering shaft a rotational torque that matches the rotation angle of the steering shaft with the target rotation angle. In the equipped vehicle,
Rotation for determining an abnormal rotation range of the steering shaft based on a current value of the actuator and a deviation between a rotation angle of the steering shaft and a rotation angle of the actuator when the steering shaft is rotated by the actuator A vehicle steering shaft rotation abnormality range determination device comprising an abnormality range determination means. The vehicle steering shaft rotation abnormality range determination device according to claim 1,
The abnormal rotation range determination means determines that there is an abnormal rotation of the steering shaft when the current value of the actuator is higher than a predetermined current value by a predetermined value or more. apparatus. In the vehicle steering shaft rotation abnormal range determination device according to claim 1 or 2,
The rotation abnormality range determination means determines that there is rotation abnormality of the steering shaft in a range between the actuator position on the steering shaft and the steering shaft rotation angle detection means position when the deviation is not less than a predetermined value. An apparatus for determining an abnormal range of steering shaft rotation of a vehicle. The vehicle steering shaft rotation abnormality range determination device according to any one of claims 1 to 3,
A steering unit that includes the steering shaft rotation angle detection means and applies a steering reaction force to the handle;
A steering unit that has the actuator and steers the steered wheel in response to the steering operation;
With
The rotation abnormality range determination device for a vehicle, wherein the rotation abnormality range determination means rotates the steering shaft by the actuator of the steering unit. The vehicle steering shaft rotation abnormality range determination device according to claim 4,
The steering shaft rotation abnormality range determination device for a vehicle, wherein the steering unit applies a predetermined torque in a direction opposite to a direction in which the actuator rotates the steering shaft. The vehicle steering shaft rotation abnormality range determination device according to any one of claims 1 to 3,
A steering unit having the actuator and applying a steering reaction force to the handle;
A steering unit that has a steering shaft rotation angle detection means, and steers the steered wheels according to the steering operation;
With
The rotation abnormality range determination device for a vehicle, wherein the rotation abnormality range determination means rotates the steering shaft by the actuator of the steering unit. In the vehicle steering shaft rotation abnormal range determination device according to any one of claims 1 to 6,
The rotation abnormality range determination device for a vehicle is characterized in that when the steering shaft is rotated by the actuator, the rotation axis is rotated within a predetermined angle range where the steering shaft rotation angle is generated. In the vehicle steering shaft rotation abnormal range determination device according to any one of claims 1 to 7,
The vehicle abnormal rotation range determination device for a vehicle, wherein when the steering shaft is rotated by the actuator, the rotation abnormal range determination means rotates the left and right rack ends. The vehicle steering shaft rotation abnormality range determination device according to any one of claims 1 to 8,
The rotation abnormality range determination device for a vehicle is characterized in that, when the steering shaft is rotated by the actuator, the rotation speed is set to a predetermined speed or less. Steering shaft rotation angle detecting means for detecting the rotation angle of the steering shaft connecting the steering wheel and the steered wheel, and an actuator for applying to the steering shaft a rotational torque that matches the rotation angle of the steering shaft with the target rotation angle. In the equipped vehicle,
An abnormal rotation range of the steering shaft is determined based on a current value of the actuator when the steering shaft is rotated by the actuator and a deviation between a rotation angle of the steering shaft and a rotation angle of the actuator. A method for determining a steering shaft rotation abnormality range of a vehicle.

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