JP2005067262A - Electric power steering control device - Google Patents

Abstract

When stopping motor control when an operation stop is requested based on an abnormality detection, the electric power capable of ensuring a good steering feeling by performing the assist torque stop request control while leaving the steering status monitoring function. A steering control device is provided.
An electric power steering control device having an abnormal motor assist amount calculation unit that stops motor control when an operation stop request is made based on abnormality detection and reduces the bias of assist torque by an electric motor. The motor assist amount calculation unit 17c takes in the detection information from the detection means for estimating a plurality of steering states, and is operating normally among the detection means for estimating the plurality of steering states when an operation stop request is made. The detection means for estimating the steering state is selected, and the assist torque stop transition control by the electric motor 9 is performed while monitoring the estimated steering value from the detection means for estimating the selected steering state.
[Selection] Figure 1

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention belongs to the technical field of an electric power steering control device that obtains steering assist torque by an electric motor.
[0002]
[Prior art]
The conventional electric power steering control device normally maintains the first switching state, i.e., the motor drive circuit, and switches to the second switching state, i.e., the voltage gradually decreasing circuit, when an abnormality is detected by the abnormality detecting means. (For example, refer patent document 1).
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 7-81590.
[0004]
[Problems to be solved by the invention]
However, in the conventional electric power steering control device, the motor control is stopped when an abnormality is detected, and the voltage gradually decreasing circuit is uniquely switched regardless of the steering situation. When the steering wheel operation is switched in the switched state, there is a problem that the steering torque becomes heavier than that during manual steering due to the remaining assist torque energized while the voltage gradually decreases.
[0005]
The present invention has been made paying attention to the above-mentioned problem, and when stopping motor control at the time of an operation stop request based on abnormality detection, it is preferable to perform the assist torque stop request control while leaving the steering situation monitoring function. An object of the present invention is to provide an electric power steering control device capable of ensuring a good steering feeling.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention,
In the electric power steering control device having an abnormal assist torque control means for stopping the motor control at the time of an operation stop request based on the abnormality detection and reducing the bias of the assist torque by the electric motor,
The abnormal-time assist torque control means takes in detection information from a plurality of detection means for estimating a steering state, and selects a detection means that is normally operating among the plurality of detection means when an operation stop request is made, The assist torque stop transition control by the electric motor is performed while monitoring the detection value from the selected detection means.
[0007]
Here, the “detection means for estimating the steering state” includes, for example, a steering torque sensor for obtaining a steering torque value, a steering angle sensor for obtaining a steering angle value, a wheel speed sensor for obtaining a wheel speed value left-right difference value, and a yaw rate. Of the yaw rate sensor that obtains the value and the lateral acceleration sensor that obtains the lateral acceleration value, two or more sensors that can estimate the turning of the steering wheel and the like.
[0008]
【The invention's effect】
Therefore, in the electric power steering control device of the present invention, the abnormal assist torque control means captures detection information from a plurality of detection means for estimating the steering state, and the plurality of detection means when an operation stop request is made. In order to perform stop transition control of the assist torque by the electric motor while monitoring the detection means from the selected detection means and monitoring the detection value from the selected detection means, the motor control is performed when the operation stop request based on the abnormality detection is performed. In the case of stopping, by performing the assist torque stop request control while leaving the steering situation monitoring function, it is possible to ensure a good steering feeling for the steering wheel turning operation and the like.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment for realizing an electric power steering control device of the present invention will be described based on a first example shown in the drawings.
[0010]
(First embodiment)
First, the configuration will be described.
FIG. 1 is an overall system diagram showing an electric power steering control apparatus according to a first embodiment. As shown in FIG. 1, the manual steering system of the first embodiment device includes a handle 1, a steering column shaft 2, a steering gear mechanism 3, tie rods 4, 5, and steered wheels 6, 7.
[0011]
The steering torque generated by rotating the handle 1 is transmitted to the steering gear mechanism 3 via the steering column shaft 2. The direction of action of the steering torque is converted by the steering gear mechanism 3 to move the tie rods 4 and 5 to change the direction of the steered wheels 6 and 7.
[0012]
As shown in FIG. 1, the manual steering system is provided with a reduction gear mechanism 8, and an electric motor 9 serving as a power booster is connected to the reduction gear mechanism 8 via an electromagnetic clutch 10.
[0013]
As shown in FIG. 1, the motor assist control system of the electric motor 9 includes a steering torque sensor 11 (detection means for estimating the steering state), a steering angle sensor 12 (detection means for estimating the steering state), Wheel speed sensor 13 (detection means for estimating the steering state), lateral acceleration sensor 14 (detection means for estimating the steering state), yaw rate sensor 15 (detection means for estimating the steering state), vehicle speed sensor 16 And a motor assist control unit 17.
[0014]
The steering torque sensor 11 is provided in the column shaft 2 and the steering gear mechanism 3, and obtains a steering torque value based on the steering torque sensor information.
[0015]
The steering angle sensor 12 is a sensor used in a four-wheel steering system (4WS), and determines a steering angle value based on steering angle sensor information input via a four-wheel steering control unit and a communication line (not shown). obtain. Instead of the steering angle sensor 12, a motor rotation angle sensor mounted on the electric motor 9 may be used.
[0016]
The wheel speed sensor 13 is a sensor used in an anti-lock brake control system (ABS), and based on wheel speed sensor information of each wheel inputted through an anti-lock brake control unit and a communication line (not shown), Get wheel speed value right / left difference value.
[0017]
The lateral acceleration sensor 14 and the yaw rate sensor 15 are sensors used in a vehicle behavior control system (VDC), and are used for lateral acceleration sensor information and yaw rate sensor information input via a vehicle behavior control unit and a communication line (not shown). Based on this, the lateral acceleration value and the yaw rate value are obtained.
[0018]
The vehicle speed sensor 16 is provided on a transmission output shaft or the like, and obtains a vehicle speed value based on vehicle speed sensor information.
[0019]
The motor assist control unit 17 controls the supply current to the electric motor 9 by using the steering torque value, the steering angle value, the wheel speed value, the left / right difference value, the lateral acceleration value, the yaw rate value, and the vehicle speed value as input information. The motor assist control unit 17 includes a sensor abnormality determination unit 17a, a normal motor assist amount calculation unit 17b, an abnormal motor assist amount calculation unit 17c (abnormal time assist torque control means), and a motor assist cutoff unit 17d. And a motor drive circuit 17e.
[0020]
The motor assist control unit 17 generates an electric motor drive signal based on the steering torque information, the steering angle information, and the vehicle speed information, and gives the electric motor drive signal to the motor drive circuit 17e. The motor drive circuit 17e adjusts the direction and magnitude of the current supplied from the vehicle battery (not shown) to the electric motor 9 according to the electric motor drive signal. Accordingly, for example, the normal motor assist amount calculation unit 17b reduces the steering force by calculating a large motor assist amount when steering in the low speed traveling region, and conversely a small motor assist amount when steering in the medium and high speed traveling region. The amount of motor assist at the time of steering the steering wheel is controlled so as to increase the steering force by calculating.
[0021]
Next, the operation will be described.
[0022]
[Sensor abnormality judgment processing]
FIG. 2 is a flowchart showing a flow of sensor abnormality determination processing executed by each sensor abnormality determination unit 17a of the motor assist control unit 17, and each step will be described below.
[0023]
In step S1, it is determined whether or not the output value of the steering torque sensor 11 is normal. If YES, the process proceeds to step S2, and if NO, the process proceeds to step S5.
[0024]
In step S2, it is determined whether or not the output value of the steering angle sensor 12 is normal. If YES, the process proceeds to step S3, and if NO, the process proceeds to step S5.
[0025]
In step S3, when it is determined that the output value is normal in both step S1 and step S2, the process proceeds to the normal motor assist amount calculation unit 17b to calculate the normal motor assist amount, and the motor drive in step S4 is performed. Transition to circuit 17e.
[0026]
In step S5, when it is determined in step S1 and step S2 that at least one of the output values is abnormal, an operation stop request determination process is performed, and the process proceeds to step S6 and step S7.
[0027]
In step S6, based on the operation stop request determination process in step S5, the normal-time motor assist amount calculation is stopped and held, and the process proceeds to step S7.
[0028]
In step S7, based on the operation stop request determination process in step S5, the process proceeds to the abnormal motor assist amount calculation unit 17c to calculate the abnormal motor assist amount, and the process proceeds to the motor drive circuit 17e in step S4.
[0029]
In step S8, whether or not the output value of the wheel speed sensor 13 is normal is determined by parallel determination processing with the sensor abnormality determination in step S1. If YES, the process proceeds to step S7. If NO, step S9 is determined. Migrate to
[0030]
In step S9, it is determined whether or not the output value of the yaw rate sensor 15 is normal. If YES, the process proceeds to step S7, and if NO, the process proceeds to step S10.
[0031]
In step S10, it is determined whether or not the output value of the lateral acceleration sensor 14 is normal. If YES, the process proceeds to step S7. If NO, the process proceeds to step S11.
[0032]
In step S11, when it is determined that all of the determinations in step S8, step S9, and step S10 are NO, the process proceeds to the motor assist cutoff processing unit 17d to set the motor assist amount to 0 (zero), and the motor in step S4 The process proceeds to the drive circuit 17e.
[0033]
[Judgment processing operation]
When the electric power steering control system is normal, the flow proceeds from step S1 to step S2 to step S3 to step S4 in FIG. 2, and the normal motor assist amount calculation unit 17b determines the normal motor assist amount as the steering torque. The electric motor drive signal, which is calculated based on the steering angle and the vehicle speed, is output to the motor drive circuit 17e.
[0034]
When at least one of the steering torque sensor 11 and the steering angle sensor 12 is abnormal and at least one of the three sensors 13, 14, 15 is normal, in FIG. → Step S2) → The flow proceeds from Step S5 and Step S6 to Step S7. On the other hand, the flow proceeds from step S8, or from step S8 to step S9, or from step S8 to step S9 to step S7. Then, in step S7 where the two join, the motor assist amount at the time of abnormality is calculated according to the flowchart shown in FIG. 3, and further, the process proceeds to step S4, where the electric motor as the calculation result in the motor assist amount calculation unit 17c at the time of abnormality is obtained. A motor drive signal is output to the motor drive circuit 17e.
[0035]
When at least one of the steering torque sensor 11 and the steering angle sensor 12 is abnormal and all the three sensors 13, 14, and 15 are abnormal, in FIG. 2, step S8 → step S9 → step S10 → The flow proceeds to step S11. In step S11, an electric motor drive signal for interrupting the drive current to the electric motor 9 is set (= no drive current). Further, the process proceeds to step S4, where a zero current is supplied from the motor drive circuit 17e to the electric motor 9. Is output.
[0036]
[Abnormal motor assist amount calculation processing]
FIG. 3 is a flowchart showing the flow of the abnormal motor assist amount calculation process executed by the abnormal motor assist amount calculation unit 17c of the motor assist control unit 17, and each step will be described below.
[0037]
In step S21, it is determined whether or not the output value of the steering torque sensor 11 is normal. If YES, the process proceeds to step S26, and if NO, the process proceeds to step S22.
[0038]
In step S22, it is determined whether or not the output value of the steering angle sensor 12 is normal. If YES, the process proceeds to step S27. If NO, the process proceeds to step S23.
[0039]
In step S23, it is determined whether or not the output value of the wheel speed sensor 13 is normal. If YES, the process proceeds to step S28, and if NO, the process proceeds to step S24.
[0040]
In step S24, it is determined whether or not the output value of the yaw rate sensor 15 is normal. If YES, the process proceeds to step S29, and if NO, the process proceeds to step S25.
[0041]
In step S25, it is determined whether or not the output value of the lateral acceleration sensor 14 is normal. If YES, the process proceeds to step S30, and if NO, the process proceeds to step S33.
[0042]
In step S26, it is determined whether or not the steering torque value obtained from the output value of the steering torque sensor 11 is equal to or less than the steering torque threshold value Th. If YES, the process proceeds to step S33. If NO, the process proceeds to step S31. Transition. Here, the steering torque threshold value Th is set to a value (a value indicating the vicinity in which the direction of operation of the steering torque changes) for performing an estimation determination that the steering operation is turned back.
[0043]
In step S27, it is determined whether the steering angle value obtained from the output value of the steering angle sensor 12 is equal to or smaller than the steering angle threshold value θ. If YES, the process proceeds to step S33, and if NO, the process proceeds to step S31. Transition. Here, the steering angle threshold θ is set to a value (a value indicating that the steering angle is in the vicinity of the steering neutral) at which it is estimated that the steering wheel operation is turned back.
[0044]
In step S28, it is determined whether or not the wheel speed value left-right difference value obtained from the output value of the wheel speed sensor 13 is equal to or less than the wheel speed value left-right difference threshold R. If YES, the process proceeds to step S33. If NO, the process proceeds to step S31. Here, the wheel speed value left / right difference value threshold value R is set to a value (a value indicating the vicinity where the wheel speed value left / right difference shifts from turning to straight traveling) for performing an estimation determination that the steering wheel operation is turned back and forth. Is done.
[0045]
In step S29, it is determined whether or not the yaw rate value obtained from the output value of the yaw rate sensor 15 is equal to or less than the yaw rate threshold value φ. If YES, the process proceeds to step S33, and if NO, the process proceeds to step S31. Here, the yaw rate threshold value φ is set to a value (a value indicating the vicinity where the acting direction of the yaw rate changes) for performing an estimation determination that the steering operation is turned back.
[0046]
In step S30, it is determined whether or not the lateral acceleration value obtained from the output value of the lateral acceleration sensor 14 is equal to or less than the lateral acceleration threshold value α. If YES, the process proceeds to step S33. If NO, the process proceeds to step S31. Transition. Here, the lateral acceleration threshold value α is set to a value (a value indicating the vicinity in which the acting direction of the lateral acceleration changes) for performing an estimation determination that the steering operation is turned back.
[0047]
In step S31, it is determined whether the motor assist amount (= λ−β * t) exceeds 0 when the steering neutral vicinity determination threshold value is not reached in any of the determinations of step S26 to step S30. If YES, the process proceeds to step S32. If NO, the process proceeds to step S33. Here, λ is a motor assist amount holding value at the time of an operation stop request, β is a motor assist amount gradually decreasing value per unit time, and t is an elapsed time after the operation stop request.
[0048]
In step S32, the motor assist amount is calculated by the equation: motor assist amount = λ−β * t, and the process returns to step S21.
[0049]
In step S33, when it is determined in any of the determinations of steps S26 to S30 that the steering neutral vicinity determination threshold value has been reached, or in the determination of step S31, the motor assist amount (= λ−β * t). Is determined to be 0 or less, the motor assist amount is set to 0.
[0050]
[Motor assist amount calculation operation at abnormal time]
For example, only the steering angle sensor 12 is abnormal, the other sensors 11, 13, 14, and 15 are normal, and the period from when the operation stop request starts until the steering torque value reaches the steering torque threshold Th is shown in FIG. In step S21, step S26, step S31, and step 32 are repeated, and the motor assist amount is given by an amount that gradually decreases with the passage of time from the motor assist amount hold value at the time of the operation stop request. Then, when the steering torque value exceeds the steering torque threshold Th, the flow proceeds from step S21 to step S26 to step S33 in FIG. 3, and in step S33, the motor assist amount is set to motor assist amount = 0. Motor assist is released.
[0051]
Further, only the steering torque sensor 11 is abnormal, the other sensors 12, 13, 14 and 15 are normal, and the period from when the operation stop request starts until the steering angle value reaches the steering angle threshold value θ is shown in FIG. In step S21, step S22, step S27, step S31, and step 32 are repeated, and the motor assist amount is given by an amount that gradually decreases with the passage of time from the motor assist amount holding value at the time of requesting the operation stop. . When the steering angle value exceeds the steering angle threshold value θ, the flow proceeds from step S21 to step S22 to step S27 to step S33 in FIG. 3, and in step S33, the motor assist amount is set to motor assist amount = 0. The motor assist is released.
[0052]
Further, the steering torque sensor 11 and the steering angle sensor 12 are abnormal, the other sensors 13, 14, and 15 are normal, and the wheel speed value left-right difference value reaches the wheel speed value left-right difference threshold R from the start of the operation stop request. In FIG. 3, the flow of going from step S21 → step S22 → step S23 → step S28 → step S31 → step 32 is repeated, and the motor assist amount is calculated from the motor assist amount holding value at the time of requesting the operation stop. It is given in an amount that gradually decreases over time. When the wheel speed value left / right difference value exceeds the wheel speed value left / right difference threshold value R, in FIG. 3, the flow proceeds to step S21 → step S22 → step S23 → step S28 → step S33. The assist amount is set to motor assist amount = 0, and the motor assist is released.
[0053]
As described above, among the steering torque sensor 11, the steering angle sensor 12, the wheel speed sensor 13, the yaw rate sensor 15, and the lateral acceleration sensor 14, except for the output value determined to be abnormal, it is used for calculating the motor assist amount at the time of abnormality. The priority is set to (1) steering torque value, (2) steering angle value, (3) wheel speed value left / right difference value, (4) yaw rate value, and (5) lateral acceleration value. The motor assist amount is gradually decreased until the threshold value is reached, and after the value becomes equal to or less than the set threshold value, an abnormal motor assist amount calculation operation for fixing the motor assist amount to 0 is executed.
[0054]
[Background technology]
A conventional electric power steering control device incorporates a torque sensor in a steering column shaft and is provided with an electric motor that rotationally drives an output shaft portion of the steering column shaft, and the vehicle speed detected by the vehicle speed sensor and the steering torque detected by the torque sensor, etc. As a parameter, the assist force is obtained, and the direction and magnitude of the current supplied to the electric motor are adjusted so that the assist force is generated. As a result, the assist force at the time of steering the steering wheel is controlled so that the assist force is increased to lighten the steering force when steering in the low-speed driving range, and the assist force is decreased to increase the steering force in the middle and high-speed range. The
[0055]
In this electric power steering control device, when a stop signal is issued from a failure diagnosis means for detecting a failure of the device, for example, an erroneous control may occur when an abnormality occurs in the torque sensor. In addition, a threshold value is set for the detected value of the torque sensor, and when the detected value of the torque sensor exceeds the threshold value, switching to manual steering is performed. In other words, an upper threshold and a lower threshold are set for the detected value of the torque sensor, and when the detected value of the torque sensor exceeds the upper threshold or the lower threshold, switching to manual steering is performed. To ensure.
[0056]
However, according to such a conventional electric power steering control device, when a failure of the device is detected, a fail-safe function is activated and the manual steering is immediately switched. That is, when a failure of the device is detected, the supply current to the electric motor instantaneously becomes zero, the assist force disappears, and the handle suddenly becomes heavy. The driver feels uneasy when this happens while driving.
[0057]
In addition, in a system that has a small vehicle weight and does not require much steering assist force, and has a small assist ratio (ratio of steering force when electric power steering is functioning to steering force when electric power steering is stopped). The steering force can be increased in a relatively short time without lowering the steering feeling.
[0058]
However, in order to prevent a decrease in steering feeling in a system with a heavy vehicle and a large assist ratio, an effect of preventing a sense of incongruity cannot be obtained unless the steering force is increased for a sufficiently long time. The problem appears prominently.
[0059]
On the other hand, Japanese Patent Application Laid-Open No. 7-81590 proposes a configuration that switches to a voltage gradual reduction circuit when an abnormality is detected. However, in the state of switching to the voltage gradual reduction circuit, the steering force is increased over a fixed time set in advance regardless of the steering situation. Therefore, energization of the motor assist torque from the drive circuit remains. For this reason, since it is necessary for the driver to apply torque that overcomes the motor assist torque to the steering wheel, there is a problem that the turning steering torque becomes heavier than that during manual steering.
[0060]
[Motor assist control action in abnormal condition]
On the other hand, in the electric power steering control device of the first embodiment, when an abnormality occurs in the electric power steering control device and the operation stop request determination is made at time t1 in FIG. The assist amount calculated based on the detected values of the torque sensor 11, the steering angle sensor 12, the vehicle speed sensor 16, and the like is held. Next, the assist amount to be added is gradually reduced with time based on the calculated value of the assist amount held. At the same time, the steering state is estimated by the steering torque sensor 11, the steering angle sensor 12, the wheel speed sensor 13, the yaw rate sensor 15, and the lateral acceleration sensor 14. Among these sensors 11, 12, 13, 14, 15, when the detected value of the sensor that has not failed reaches a preset threshold value, it is determined that the steering operation has been switched back, and the above-mentioned gradually. The assist amount is fixed at 0 (zero) at time t2 in FIG. 4 while the assist amount added to is gradually decreasing.
[0061]
By calculating the motor assist amount at the time of abnormality, when the driver performs the steering wheel turning operation while the assist amount is gradually decreasing, it is estimated that the switching operation is performed based on the selected sensor output value. Since the assist amount is sometimes fixed to zero (motor assist is released), the steering wheel turning operation can be performed with the steering torque by manual steering after the turning operation is estimated.
[0062]
FIG. 4 is a time chart when the driver performs the steering wheel turning operation while the assist amount is gradually decreasing due to the operation stop request. When the driver turns the steering wheel, the steering torque direction applied to the steering wheel 1 changes, then the steering angle passes near neutral, and the steered wheels 6 and 7 pass near neutral with a slight response delay. In addition, the response is delayed and the yaw rate direction of the vehicle changes, and the lateral acceleration of the vehicle changes.
[0063]
Therefore, in the case of estimating the steering wheel return based on the steering torque value, the motor assist amount can be fixed to 0 at the earliest timing t2. Hereinafter, in the case of the steering wheel return estimation based on the steering angle value, the motor assist amount can be fixed to 0 at the timing t3, and in the case of the steering wheel return estimation based on the wheel speed value left / right difference value, the motor assist amount is determined at the timing t4. It can be fixed at 0, the motor assist amount can be fixed at 0 at the timing of t5 in the case of the steering wheel return estimation by the yaw rate value, and the motor assist amount is 0 at the timing of t6 in the case of the steering wheel return estimation by the lateral acceleration value. The time relationship is t2 <t3 <t4 <t5 <t6, which matches the above priority order.
[0064]
Next, the effect will be described.
In the electric power steering control device of the first embodiment, the effects listed below can be obtained.
[0065]
(1) In the electric power steering control device having an abnormal motor assist amount calculation unit 17c that stops motor control when an operation stop request based on abnormality detection is requested and reduces the bias of assist torque by the electric motor 9, the abnormal motor The assist amount calculation unit 17c fetches detection information from a plurality of detection means for estimating the steering state, selects a detection means that is operating normally from the plurality of detection means when an operation stop request is made, and selects Since the stop transition control of the assist torque by the electric motor 9 is performed while monitoring the detection value from the detection means, when the motor control is stopped at the time of the operation stop request based on the abnormality detection, the assist torque is stopped while leaving the steering situation monitoring function. By performing the on-demand control, a good steering feeling can be ensured.
[0066]
(2) The abnormal-time motor assist amount calculation unit 17c urges the assist torque by the electric motor 9 after the steering state based on the detected value becomes equal to or less than a set threshold value estimated to be the turning of the steering wheel operation. Therefore, the steering wheel turning operation can be ensured by the operation force by the manual steering even when the steering wheel turning operation is performed when the operation stop is requested.
[0067]
(3) Until the detected value from the detecting means for estimating the selected steering state becomes equal to or less than a set threshold value estimated to be a turnover of the steering wheel operation, the abnormal-time motor assist amount calculation unit 17c In order to maintain the motor assist amount calculated from the motor assist amount holding value λ at the time of requesting operation stop, the motor assist amount gradually decreasing value β per unit time, and the elapsed time t after the operation stop request, operation stop determination is performed. Thereafter, when the driver performs an operation of returning the steering wheel to the neutral position, it is possible to ensure a good steering feeling without a sense of incongruity such that the steering torque gradually increases.
[0068]
(4) The detection means for estimating the steering state includes a steering torque sensor 11 for obtaining a steering torque value, a steering angle sensor 12 for obtaining a steering angle value, and a wheel speed sensor 13 for obtaining a wheel speed value left-right difference value; A yaw rate sensor 15 for obtaining a yaw rate value and a lateral acceleration sensor 14 for obtaining a lateral acceleration value, and the abnormal motor assist amount calculation unit 17c calculates an abnormal motor assist amount except for an output value determined to be abnormal. The priority order is the steering torque value, steering angle value, wheel speed value left / right difference value, yaw rate value, and lateral acceleration value. In order to fix the value to 0, when the driver performs a turn-back operation after determining the operation stop, the output value from the normal sensor is used and the motor assist amount is set to 0 at the earliest timing. Can be fixed.
[0069]
(5) Since the steering angle sensor is a sensor used in a four-wheel steering control system, the sensor of the four-wheel steering control system is used for estimation of steering wheel return instead of the steering torque sensor 11 when the steering torque sensor 11 fails. can do.
[0070]
(6) Since the lateral acceleration sensor 14 is a sensor used in the vehicle behavior control system, the sensor of the vehicle behavior control system is used for steering wheel turnover estimation instead of the steering torque sensor 11 when the steering torque sensor 11 fails. be able to.
[0071]
(7) Since the wheel speed sensor 13 is a sensor used in the anti-lock brake control system, the sensor of the anti-lock brake control system is used to estimate the steering wheel return instead of the steering torque sensor 11 when the steering torque sensor 11 fails. Can be used.
[0072]
(8) Since the yaw rate sensor 15 is a sensor used in the vehicle behavior control system, the sensor of the vehicle behavior control system is used for steering wheel turnover estimation instead of the steering torque sensor 11 when the steering torque sensor 11 fails. Can do.
[0073]
The electric power steering control device of the present invention has been described based on the first embodiment, but the specific configuration is not limited to the first embodiment, and each claim of the claims Design changes and additions are allowed without departing from the gist of the invention.
[0074]
For example, in the first embodiment, as detection means for estimating a plurality of steering states, a steering torque sensor for obtaining a steering torque value, a steering angle sensor for obtaining a steering angle value, and a wheel speed sensor for obtaining a wheel speed value left-right difference value Although an example using a yaw rate sensor that obtains a yaw rate value and a lateral acceleration sensor that obtains a lateral acceleration value has been shown, it is possible to monitor a steering situation including a steering wheel turnback estimation among these sensor groups. The case where two or more sensors are included in the sensor group to which the above sensors are added is included in the present invention.
[0075]
In the first embodiment, an example in which the sensors used in the four-wheel steering control system, the vehicle behavior control system, and the anti-lock control system are used is shown. This includes the case of using a sensor that can monitor the steering situation including
[Brief description of the drawings]
FIG. 1 is an overall system diagram showing an electric power steering control apparatus according to a first embodiment.
FIG. 2 is a flowchart showing the flow of a sensor abnormality determination process executed by each sensor abnormality determination unit of the motor assist control unit of the first embodiment apparatus.
FIG. 3 is a flowchart showing a flow of an abnormal motor assist amount calculation process executed by an abnormal motor assist amount calculation unit of the motor assist control unit of the first embodiment apparatus;
FIG. 4 is an operation stop request determination, a normal motor assist amount, and a steering torque value when the driver performs a steering wheel turning operation while the assist amount is gradually decreasing due to an operation stop request in the first embodiment apparatus. 4 is a time chart showing characteristics of a steering angle value, a wheel speed value, a left / right difference value, a yaw rate value, a lateral acceleration value, and an abnormal motor assist amount.
[Explanation of symbols]
1 Handle
2 Steering column shaft
3 Steering gear mechanism
4,5 Tie rod
6,7 steered wheels
8 Reduction gear mechanism
9 Electric motor
10 Electromagnetic clutch
11 Steering torque sensor (detection means for estimating the steering state)
12 Steering angle sensor (detection means for estimating the steering state)
13 Wheel speed sensor (detection means for estimating the steering state)
14 Lateral acceleration sensor (detection means for estimating the steering state)
15 Yaw rate sensor (detection means for estimating the steering state)
16 Vehicle speed sensor
17 Motor assist control unit
17a Each sensor abnormality judgment part
17b Motor assist amount calculation unit at normal time
17c Abnormal motor assist amount calculator (abnormal assist torque control means)
17d Motor assist block
17e Motor drive circuit

Claims (8)

In the electric power steering control device having an abnormal assist torque control means for stopping the motor control at the time of an operation stop request based on the abnormality detection and reducing the bias of the assist torque by the electric motor,
The abnormal-time assist torque control means takes in detection information from a plurality of detection means for estimating a steering state, and selects a detection means that is normally operating among the plurality of detection means when an operation stop request is made, An electric power steering control device that performs assist torque stop transition control by an electric motor while monitoring a detection value from a selected detection means. In the electric power steering control device according to claim 1,
The abnormal-time assist torque control means releases the biasing of the assist torque by the electric motor after the steering state based on the detected value becomes equal to or less than a set threshold value that is estimated to be the return of the steering operation. Electric power steering control device. In the electric power steering control device according to claim 2,
The abnormal-time assist torque control means, until the detected value from the selected detection means is equal to or less than a set threshold value estimated to be the return of the steering operation, a motor assist amount holding value at the time of operation stop request, An electric power steering control device that maintains a motor assist amount calculated from a gradually decreasing value of a motor assist amount per unit time and an elapsed time after an operation stop request. In the electric power steering control device according to any one of claims 1 to 3,
The detection means includes a steering torque sensor for obtaining a steering torque value, a steering angle sensor for obtaining a steering angle value, a wheel speed sensor for obtaining a wheel speed value left-right difference value, a yaw rate sensor for obtaining a yaw rate value, and a lateral acceleration value. A lateral acceleration sensor
The abnormal assist torque control means is used to calculate an abnormal motor assist amount except for an output value determined to be abnormal, and the priority order is a steering torque value, a steering angle value, a wheel speed value, a left / right difference value, a yaw rate. An electric power steering control device characterized in that a motor assist amount is fixed to 0 after a value and a lateral acceleration value are set, and the value falls below a set threshold value according to priority. In the electric power steering control device according to claim 4,
The electric power steering control device, wherein the steering angle sensor is a sensor used in a four-wheel steering control system. In the electric power steering control device according to claim 4,
The electric power steering control device, wherein the lateral acceleration sensor is a sensor used in a vehicle behavior control system. In the electric power steering control device according to claim 4,
The wheel speed sensor is a sensor used in an antilock brake control system. In the electric power steering control device according to claim 4,
The electric power steering control device, wherein the yaw rate sensor is a sensor used in a vehicle behavior control system.

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