JP4556657B2 - Vehicle steering control device - Google Patents

Description

  The present invention belongs to the technical field of a vehicle steering control device that performs failure diagnosis.

Conventionally, to prevent malfunction of the system due to failure of the motor and its drive circuit, the contact check detection circuit setting digit relay is known to the power supply line of the motor drive circuit. When performing relay failure diagnosis, the relay contact is turned off, a PWM control signal is output to the motor, and the terminal voltage change of the capacitor placed in parallel with the motor is determined to detect whether the relay is stuck on. (For example, refer to Patent Document 1).
JP-A-8-293238

  However, in the above circuit, the relay diagnosis needs to be turned ON / OFF with the motor stopped, so when this circuit is applied as a motor failure diagnosis circuit that outputs torque to the vehicle steering system, Stopping the motor while driving affects steering, so failure diagnosis can only be performed at the initial system diagnosis. As a result, when an abnormality occurs in the motor drive control unit during system operation, there is a possibility that the current signal to the motor cannot be cut off due to the relay being stuck ON.

  The present invention has been made paying attention to the above-mentioned problem, and the object of the present invention is for a vehicle capable of performing failure diagnosis of connection / disconnection means (relay) without affecting steering even during system operation. The object is to provide a steering control device.

In order to achieve the above object, the present invention provides:
At least one of the steering mechanism that applies steering torque to the steering wheel and the reaction force mechanism that adds reaction force torque to the steering wheel has a plurality of torque generating means for generating torque with electric power from the power source. ,
Torque control means for controlling the amount of torque generated by the plurality of torque generating means;
A plurality of connecting / disconnecting means respectively provided corresponding to the plurality of torque generating means so as to hold or cut off power supply from the power source to each of the plurality of torque generating means ;
An interruption diagnosis means for diagnosing whether one of the plurality of connection means can be interrupted,
The torque control unit divides a total torque command value and distributes the total torque command value to each of the plurality of torque generation units, and controls a torque generation amount of each of the plurality of torque generation units based on the distributed torque command value. Because
The blocking diagnostic means by that diagnosis Sometimes, the torque control means, the zero torque command value to be distributed to the torque generating means corresponding to the engaging and disengaging means for said shut-off diagnosis means diagnoses of the plurality of disconnection device In addition, the torque command value distributed to the torque generating means corresponding to the connection / disconnection means that is not diagnosed by the interruption diagnosis means is increased more than before the diagnosis is started by the interruption diagnosis means .

In the present invention, when one of the torque generating means for diagnosis is stopped, to compensate the torque generation amount of other torque generating means insufficient, affecting the steering even during system operation Diagnosis of the connecting / disconnecting means can be carried out.

  Hereinafter, the best mode for carrying out the present invention will be described based on Examples 1 to 3.

First, the configuration will be described.
FIG. 1 is an overall configuration diagram illustrating a steer-by-wire system to which a vehicle steering apparatus according to a first embodiment is applied.

As shown in FIG. 1, a steer-by-wire system to which the apparatus of the first embodiment is applied includes a steering unit 3 having a handle 1 and a steering reaction force motor (a reaction force mechanism that applies reaction force torque to the handle) 2. Between the front wheels (steering wheels) 4 and 4 and the two steered motors (the torque generating means of the steering mechanism for adding the steering torque to the steered wheels) 5a and 5b. There is no mechanical connection.

  The steering unit 3 includes a steering wheel 1, a steering shaft 7, a steering reaction force motor 2 provided to the steering shaft 7 via a reduction gear mechanism (not shown), a steering angle sensor 8, a torque sensor 9, Have

  The steered portion 6 includes two steered motors 5a and 5b, a steered shaft 10 driven by the steered motors 5a and 5b, and a steering gear mechanism 11 having a rack that meshes with a pinion of the steered shaft 10. And front wheels 4, 4 connected via tie rods 12, 12 provided at both ends of the steering gear mechanism 11.

  The steering reaction force motor 2 simulates the road surface reaction force by outputting a steering reaction force torque to the steering shaft 7 based on the command current value supplied from the steering reaction force controller 13. The steering reaction force controller 13 supplies the command current value while referring to the actual current value of the steering reaction force motor 2 based on the target reaction force command value set by the steering controller 14.

  The two turning motors 5a and 5b output turning torque to the turning shaft 10 based on the command current value supplied from the turning angle controller (torque control means) 15 to turn the front wheels 4 and 4. Rudder. The turning angle controller 15 supplies a command current value based on the target turning angle command value set by the steering controller 14 while referring to the actual current values of the turning motors 5a and 5b.

  The steering controller 14 includes a steering angle from the steering angle sensor 8, a steering torque from the torque sensor 9, a vehicle speed from the vehicle speed sensor 30, a yaw rate sensor 31 as vehicle behavior state quantity detection means, and a yaw rate and lateral G from the lateral G sensor 32. Given as input information. Further, the motor angle of the steering reaction force motor 2 is inputted from the steering reaction force controller 13, and the motor angles of the respective turning motors 5 a and 5 b are inputted from the turning angle controller 15.

Steering controller 14, based on each input information, and sets the target turning angle command value of the front wheel 4 and 4, to set the target steering reaction force command value to be added to the handle 1, the steering angle controller 15 and the steering Output to the reaction force controller 13.

FIG. 2 is a control block diagram illustrating the turning angle controller 15 according to the first embodiment.
The turning angle controller 15 includes two turning angle controllers 15a and 15b. The steered motors 5a and 5b drive the steered shaft 10 to steer the front wheels 4 and 4. The turning angle controllers 15a and 15b perform angle control of the turning motors 5a and 5b according to the target turning angle command value input from the steering controller 14 which is a host system.

  The turning angle controllers 15a and 15b are composed of angle control calculation units 16a and 16b, current control calculation units 17a and 17b, and motor relay diagnosis processing units (cut-off diagnosis means) 18a and 18b. Further, the turning angle controllers 15a and 15b include a communication bus interface 19, perform data communication with the steering controller 14, and transmit and receive data to and from the angle control calculation units 16a and 16b and the current control calculation units 17a and 17b.

  Further, the turning angle controller 15 includes an interface for reading signals from the angle sensors 20a and 20b that detect the motor rotation angles of the turning motors 5a and 5b. Further, an interface for reading signals from the current sensors 21a and 21b for detecting the current flowing through the steering motors 5a and 5b, an interface for outputting command signals to the motor drivers 22a and 22b for driving the steering motors 5a and 5b, and a motor And relays (connecting / disconnecting means) 24a and 24b provided between the drivers 22a and 22b and a power source (power source) 23.

  The relays 24a and 24b are, for example, for holding or cutting off the power supply from the power source 23 to the motor drivers 22a and 22b when the steering motors 5a and 5b fail. Different from MOSFET relay (not shown) for PWM control. Incidentally, the MOSFET relay is provided between the motor drivers 22a and 22b and the steered motors 5a and 5b, respectively.

  In the turning angle controller 15, the angle control calculation units 16a and 16b calculate the target current command values of the corresponding turning motors 5a and 5b according to the target turning angle command values, and send them to the current control calculation units 17a and 17b. Output. The current control calculation units 17a and 17b output the current command value to the motor drivers 22a and 22b based on the deviation between the target current command value and the actual current value from the current sensors 21a and 21b.

  The motor relay diagnosis processing units 18a and 18b diagnose whether or not the relays 24a and 24b of the motor drivers 22a and 22b are operating normally. As a relay diagnosis method, for example, when the relay contact for diagnosis is turned OFF and a PWM control signal is output to the corresponding motor, if the current value of the motor is not zero, the relay is fixed ON. The turning angle controller 15 sets the command current value to the corresponding motor to zero when the ON fixation of the relay is detected, and continues the turning control using the other motor.

  Further, when the motor relay diagnosis is performed, the turning angle controller 15 calculates a distribution command value from the total torque command value corresponding to the target turning angle command value, and distributes it to the steering motor that has not been diagnosed. To do. As a result, motor relay diagnosis during traveling becomes possible.

  Steering angle controllers 15a and 15b including the steering motors 5a and 5b, current sensors 21a and 21b, motor drivers 22a and 22b, angle control calculation units 16a and 16b, and current control calculation units 17a and 17b, an angle sensor 20a, 20b comprises motor drive control part a, b by one set combination, respectively, and this is connected to the turning shaft 10 via the reduction gear mechanism as a several motor drive control part.

Next, the operation will be described.
[Motor relay diagnostic logic]
Hereinafter, in the turning angle controller 15, a motor drive control unit that calculates a distribution command value from a total torque command value that is a target turning angle command value of the turning motors 5a and 5b and issues a motor relay diagnosis command is driven by the main motor. It is called a control unit, and other motor drive control units are called sub motor drive control units. The conditions for becoming the main motor drive control unit are determined in advance in the order of the motor drive control unit a and the motor drive control unit b, but the conditions for becoming the main motor drive control unit are not limited to this.

  When one steered shaft 10 is operated by two steered motors, the rotation of the two steered motors interferes with each other due to a calculation error or a sensor error between motor drive control units corresponding to the individual steered motors. In the first embodiment, two motor drive control units a and b are provided to provide a redundant configuration. One of the motor drive control units a and b is a main motor drive control unit, and the other is a sub motor. The drive control unit.

Then, the angle control calculation and the torque command value calculation of the turning is performed collectively main motor drive control unit, the sub-motor drive control unit of the motor driven using the torque command value sent from the main motor drive control unit Do. At this time, the main motor drive control unit calculates the torque command value for each motor drive control unit by dividing the total torque command value by the number of motor drive control units capable of driving the steering motor in the redundant configuration. Yes.

In this way, by using the control result of the main motor drive control unit, it is possible to suppress the occurrence of mutual interference when each of the steered motors is operated by a plurality of motor drive control units. . At this time although the motor drive control unit became sub has implemented similarly angle control calculation and the torque command value calculation and the main, indeed torque command value to the motor is sent from the main torque The command value is used . When the main is defective, the switching of the main motor drive control unit so that the motor drive control unit which has been a sub is the main generated before.

At the time of the main switching, the torque command value of the newly main motor drive control unit is different from the torque command value of the old main motor drive control unit due to a difference in calculation error or sensor error between the motor drive control units. This deviation may appear as torque fluctuation. Since the torque fluctuation affects the turning angle control, it affects the behavior of the vehicle. Therefore, the smaller the torque fluctuation, the better. It is desirable that the torque fluctuation does not occur as much as possible at the time of main switching.

[Motor relay diagnostic control processing]
FIG. 3 is a flowchart showing the flow of the motor relay diagnosis control process executed by the steering angle controller 15 of the first embodiment, and each step will be described below.

  In step S1, a vehicle behavior state and a steering state are acquired, and the process proceeds to step S2. Information on the steering angle and steering angular velocity of the steering wheel 1 is acquired as the vehicle behavior state quantity, such as the yaw rate and lateral G, and the steering state quantity.

  In step S2, motor relay diagnosis is enabled when the vehicle behavior state quantity and the steering state quantity acquired in step S1 satisfy a certain criterion. If it is determined that the diagnosis is possible, the process proceeds to step S3. If it is determined that the diagnosis is impossible, the process proceeds to step S1.

  Here, the determination criterion of the motor relay diagnosis is that any value indicating the vehicle behavior state such as the yaw rate or the lateral G is not in a turning limit state where the wheel starts to slip (corresponding to a turning limit determination means). The following are the starting conditions.

Start condition: Diagnosis starts when steering is in progress or while steering is being held.
When an abnormality is detected, there is a time until it is determined that an abnormality has occurred. Normally, when an abnormal state has occurred for a certain period of time or longer, the abnormality is determined. The time until this diagnosis is confirmed will hold the steering state when it is normal, so when the abnormality of the main motor drive control unit is detected during the motor relay diagnosis near neutral or during steering Even if there is, the torque fluctuation hardly occurs at the time of main switching (1N or less), so there is no influence on the vehicle behavior and the motor relay diagnosis in a safe situation is possible.

  In step S3, the number of motor drive control units operating normally in the system is confirmed. Motor relay diagnosis is possible when the number of motor drive control units in normal operation is at least two or more. At this time, at least two of the motor drive control unit for diagnosis and the motor drive control unit for continuing the control are necessary. In the first embodiment, when both of the two motor drive control units a and b are operating normally, the process proceeds to step S4, and when one is not operating normally, the process proceeds to return.

In step S4, the motor drive control unit that performs the main ( calculates, distributes, and commands the torque command value ) is determined from the motor drive control unit that is operating normally.

In a normal state, the main motor drive control unit calculates a torque command value for each motor drive control unit by the following calculation formula. Here, as the main motor drive control unit , it is preferable to select the one with the highest reliability according to the thermal load of the motor, the abnormality occurrence rate, and the like.
Torque command value = total torque command value / number of operable motors, or
Motor drive control unit a = total torque command value × distribution rate a
Motor drive control unit b = total torque command value × distribution rate b

Here, as in the first embodiment, when there are two components of the motor drive control unit, the main is the motor drive control unit a and the motor relay diagnosis motor drive control unit is the motor drive control unit b. In step S5 and subsequent steps, the motor relay diagnosis motor drive control unit b calculates a torque command value in step S13 separately from the torque command value of the main motor drive control unit a. When the main motor drive control unit a becomes abnormal, main switching occurs, the motor relay diagnosis is interrupted, and the motor is driven using the torque command value calculated in step S13.

  In step S5, the vehicle behavior state quantity and the steering state quantity are acquired, and the process proceeds to step S6.

  In step S6, a torque distribution change rate ΔT is obtained from the vehicle behavior state quantity and the steering state quantity confirmed in step S5, and the process proceeds to step S7.

  In a normal state, each motor drive control unit controls each steered motor with the distributed torque command value. If the total torque command value is abruptly distributed during motor relay diagnosis, there is a concern that the load on the motor increases. However, considering the vehicle behavior in the case of failure during diagnosis, it is desirable that the diagnosis time be as short as possible.

Therefore, the torque distribution change rate ΔT is obtained from the torque command value distribution amount and the vehicle behavior state amount. For example, the distribution time is assumed to be within the time from when an abnormality occurs until it appears as a vehicle behavior (about 25 msec), and the slope (ΔT0) at this time is expressed by the following equation according to the vehicle behavior state quantity (yaw rate or lateral G): By making it variable, the vehicle behavior is prevented from appearing as much as possible, and the thermal load on the motor is reduced.
ΔT = ΔT0 × G1 × G2
here,
.DELTA.T0: sub motor drive control unit of the torque command value distribution amount / distribution time sub motor drive control unit of the torque command value distribution amount: torque command value sub motor drive control unit - the total number of torque command value / N (N is the motor drive control unit )
G1: Correction gain according to yaw rate
G2: A correction gain corresponding to the lateral G.

  The correction gain G1 corresponding to the yaw rate is set based on the map of FIG. G1 is set to 1 until the yaw rate reaches a predetermined value, and is set to gradually decrease when the yaw rate is exceeded. Further, the correction gain G2 corresponding to the lateral G is set based on the map of FIG. G2 is set to 1 until the lateral G reaches a predetermined value, and is set so as to gradually decrease when the lateral G is exceeded.

  That is, when the yaw rate or the lateral G is less than a predetermined value and there is almost no influence on the vehicle behavior due to one motor stop, the torque distribution change rate ΔT is increased, the torque distribution is performed quickly, and the diagnosis time To shorten the time. On the other hand, when the yaw rate or the lateral G is large and the influence on the vehicle behavior due to the motor stop is large, the torque distribution change rate ΔT is reduced to reduce the influence on the vehicle behavior.

In step S7, a torque command value is calculated for each motor drive control unit from the torque distribution change rate ΔT calculated in step S6, and the process proceeds to step S8. Here, the main motor drive control unit calculates a torque command value for each motor drive control unit by the following calculation formula.

For example, when the main is the motor drive control unit a and the motor relay diagnosis motor drive control unit is the motor drive control unit b,
Torque command value of motor drive controller a = total torque command value × distribution rate a−ΣΔT
Torque command value of motor drive control unit b = total torque command value × distribution rate b−ΣΔT
And

  In step S8, it is determined whether or not the torque command value calculated in step S7 is within the motor rating. If YES, the process proceeds to step S9. If NO, the process proceeds to step S20.

  In step S9, the main motor drive control unit transmits the distribution command value calculated in step S7 to each motor drive control unit, and proceeds to step S10.

  In step S10, the main motor drive control unit determines from the current distribution command value whether the conditions allow motor relay diagnosis. If YES, the process proceeds to step S11. If NO, the process proceeds to step S5. The condition for enabling the motor relay diagnosis is determined by the fact that the distribution has been completed.

  In step S11, when the main motor drive control unit determines that the motor relay diagnosis is possible in step S10, the motor relay diagnosis motor drive control unit is notified of a diagnosis command, and the process proceeds to step S12.

  In step S12, the main motor drive control unit determines whether the diagnosis of the motor relay diagnosis motor drive control unit is completed. If YES, the process proceeds to step S18, and if NO, the process proceeds to step S5.

In step S13, when it becomes the sub motor drive control unit, a torque command value used when the main motor drive control unit becomes abnormal during diagnosis is calculated, and the process proceeds to step S14.

In step S14, the motor relay diagnosis motor drive control unit determines whether a diagnosis command is notified from the main motor drive control unit . If YES, the process proceeds to step S15. If NO, the process proceeds to return.

  In step S15, the motor relay diagnosis processing unit 18a (18b) of the motor relay diagnosis motor drive control unit cuts off the relay to perform motor relay diagnosis, and proceeds to step S16.

  In step S16, the motor relay diagnosis motor drive control unit determines whether or not the motor relay diagnosis is completed. If YES, the process proceeds to step S17. If NO, the process proceeds to step S15.

In step S17, the motor relay diagnosis motor drive control unit notifies the main motor drive control unit of the end of the motor relay diagnosis and shifts to return.

  In step S18, the main motor drive control unit performs steps S5 to S8 to distribute command values, and then proceeds to step S19.

  In step S19, it is determined whether or not the command value distribution value in step S18 has become a normal distribution value. If YES, the process proceeds to return, and if NO, the process proceeds to step S18.

  In step S20, the main motor drive control unit notifies the sub motor drive control unit that the diagnosis is stopped, and the process proceeds to return.

[Motor relay diagnostic control operation]
In the flowchart of FIG. 3, in steps S1 to S4, the vehicle behavior state and the steering state are confirmed in order to start the motor relay diagnosis as the diagnosis start condition determination process. When the motor relay diagnosis is performed, it is determined that the diagnosis can be started when it is determined that the influence on the system is small even if an abnormality occurs in the motor drive control unit. The diagnosis start conditions are not limited to the following.

  In steps S5 to S9, as the command value distribution process, when the main motor drive control unit is established, the torque command value distributed to each motor drive control unit is calculated while changing the distribution rate according to the vehicle behavior state and the steering state. To do.

In steps S10 to S12, as the main diagnosis process, the main motor drive control unit notifies the motor relay diagnosis motor drive control unit of a relay diagnosis start command, and waits for the end of the relay diagnosis.

In steps S13 to S17, as a sub-diagnosis process, the main motor drive control is performed to deal with a case where the torque command value is interrupted due to a failure of the main motor drive control unit during diagnosis when the sub motor drive control unit is used. A torque command value is calculated separately from the unit. When it becomes a motor relay diagnosis motor drive control unit, it waits for a relay diagnosis command from the main motor drive control unit, performs relay diagnosis at the time of receiving the command, and gives an end notification.

  In steps S18 and S19, as a post-diagnosis process, command value distribution is performed at the end of the diagnosis, and the process proceeds to a normal process.

[Distribution of torque command value during motor relay diagnosis]
In the first embodiment, the motor drive torque command value of the motor drive control unit that performs motor relay diagnosis during system operation is set to 0 [N / m], and the total torque command that is insufficient in other motor drive control units. By distributing the value in a direction that compensates for the value, motor relay diagnosis can be performed while continuing the steering control.

That is, the motor drive control unit for the motor relay diagnosis, the main motor drive control unit of the torque command value calculated in order to perform the angle control, changing the distribution ratio of the torque command value for the motor drive control unit Thus, it is possible to make it equivalent to 0 [N / m]. Thus, the motor relay diagnosis is possible because the motor is stopped while the steering control is continued. At this time, the total torque command value that is deficient corresponding to 0 [N / m] will be compensated by the remaining sub motor drive control unit by changing the distribution ratio. Therefore, the system performs motor relay diagnosis. Will not be operating as normal state.

[Diagnosis start determination action according to vehicle behavior state and steering state]
In the first embodiment, the motor relay diagnosis is started by determining that the diagnosis is possible when the vehicle behavior state (yaw rate or lateral G) and the steering state (neutral steering) satisfy certain criteria. Even when an abnormality occurs in another motor drive control unit during diagnosis, the influence on the system is suppressed.

  That is, the steered motor of the motor drive control unit during motor relay diagnosis becomes inactive. Therefore, the system is operated by the remaining motor drive control unit. However, if an abnormality is detected in the remaining motor drive control units in this state, it is necessary to immediately interrupt the motor relay diagnosis. Here, if an abnormality occurs when the total torque command value is large, the motor torque may change suddenly, which may affect the vehicle behavior.

  Therefore, it is possible to reduce the influence on the system by determining the diagnosis start condition based on the vehicle behavior state and the steering state. This is because when the yaw rate or the lateral G is small, the total torque command value is small, and the distribution amount to each motor drive control unit is also small. As a result, a sudden change in torque can be suppressed even when an abnormality occurs, and the influence on the system can be reduced. In addition, when the yaw rate or the lateral G is small, even if a sudden torque change occurs, the influence on the vehicle behavior is small.

[Torque distribution change rate changing action according to vehicle behavior state and torque command value distribution amount]
In the first embodiment, the torque distribution change rate ΔT is changed according to the vehicle behavior state and the torque command value distribution amount, and the distribution rate is gradually changed, thereby suppressing the influence on the vehicle behavior and the total torque command. The load on the motor of the motor drive control unit on the side that compensates for the value is reduced.

That is, in the torque command value distribution, the motor drive control unit that supplements the torque command value adds and outputs the torque command value that has been distributed. Therefore, when the number of motor drive control units is small, the load on the motor increases during the motor relay diagnosis. Furthermore, when the distribution ratio is changed instantaneously, the torque command value may be doubled, and the load on the motor increases rapidly.

  Therefore, the load on the motor can be reduced by varying the torque distribution change rate ΔT according to the current steering state and torque command value distribution amount. This is because the total torque command value is originally small in the steering state when the yaw rate and lateral G are small, and even if the distribution rate is changed instantaneously, the load on the motor can be reduced, so the distribution rate is changed in a short time. It is possible. Conversely, when the total torque command value is large, for the reasons described above, the distribution ratio is not instantaneously changed gradually over a certain period of time, so that the torque command value for the motor increases rapidly. It becomes possible to reduce.

[Torque command value calculation by sub motor drive control unit]
In the first embodiment, the motor relay diagnosis motor drive control unit (sub motor drive control unit) performs angle control calculation on the system in the same manner as the main motor drive control unit, independently calculates the torque command value, and performs main control during motor relay diagnosis. Even when the motor drive control unit fails, normal control is performed by using a uniquely calculated torque command value.

  That is, the steered motor of the motor drive control unit during motor relay diagnosis becomes inactive. For this reason, the system is operated by the remaining motor drive control units. However, when an abnormality is detected by the remaining motor drive control units, it is necessary to immediately interrupt the motor relay diagnosis and return to the steady state. Therefore, the motor drive control unit that performs motor relay diagnosis performs angle control calculation for the system in the same manner as the main motor drive control unit, and calculates the torque command value independently, so that the torque can be immediately generated when the main motor drive control unit is abnormal. The command value can be switched.

[Motor relay diagnosis]
When the total torque command value is distributed, instantaneously changing the torque command value from 50% to 100% for one motor increases the load on the motor. As shown in FIG. 6, the motor drive control unit a, which is the main motor drive control unit, sets the torque distribution change rate ΔT obtained from the total torque command value, the vehicle behavior state quantity (yaw rate, lateral G, etc.) and the distribution time. On the basis of this, the load on the motor is reduced by providing an inclination that gradually changes the distribution rate from the point A where distribution starts. In addition, the motor load can be further reduced by making the time for the inclination at this time variable by the vehicle behavior state quantity (yaw rate, lateral G, etc.).

Next, the motor relay diagnosis starting after 25 msec, the motor relay diagnosis motor drive control unit so that the distribution is completed at Do that point B and OA command to start the motor relay diagnosis. At point C, the main motor drive control unit is notified of the completion of the motor relay diagnosis, and the main motor drive control unit performs the command value distribution process again as a post-diagnosis process and returns to the normal state. By performing the above processing for each motor drive control unit, motor relay diagnosis can be performed without affecting the steering control while continuing the steering control.

Next, the effect will be described.
In the vehicle steering control apparatus according to the first embodiment, the following effects can be obtained.

  (1) Two motors 5a and 5b for applying steering torque to the front wheels 4 and 4, and a steering angle controller 15 for controlling the torque generation amount of the two motors 5a and 5b, and the two motors 5a and 5b Relays 24a and 24b provided so as to hold or cut off the torque of the motors, and motor relay diagnosis processing units 18a and 18b for diagnosing whether one of the relays 24a and 24b can be cut off. The steering angle controller 15 distributes the torque generation amount of the motor corresponding to the relay to be diagnosed to the other motors before and after the start of the interruption diagnosis by the motor relay diagnosis processing units 18a and 18b. Therefore, when one motor stops for diagnosis, the other motors compensate for the insufficient torque generation amount, so that the relay can be diagnosed without affecting steering even during system operation.

  (2) The steered angle controller 15 suppresses a rapid increase in the load of the torque-distributed motor in order to decrease the torque change amount to be distributed as the torque distribution amount to be distributed to the motor to which torque is distributed increases. it can.

  (3) Vehicle behavior state quantity detecting means (yaw rate sensor 31, lateral G sensor 32) for detecting the behavior state quantity of the vehicle is provided, and the turning angle controller 15 is a motor that distributes torque as the vehicle behavior state quantity increases. Since the amount of torque change distributed to the vehicle is reduced, it is possible to diagnose the relay during system operation while suppressing the influence on the vehicle behavior.

  (4) Since the motor relay diagnosis processing units 18a and 18b do not perform diagnosis when the torque generation amount of the motor to which torque is distributed is equal to or greater than a predetermined value, it is possible to prevent an excessive load from being applied to the motor.

  (5) Provided with a turning limit determination means for determining the turning limit of the vehicle, and the motor relay diagnosis processing units 18a and 18b do not make a diagnosis when the vehicle is at the turning limit, thereby preventing the vehicle behavior from being affected. Yes, motor relay diagnosis can only be performed in a safe situation.

First, the configuration will be described.
FIG. 7 is a control block diagram showing the turning angle controller 15 of the second embodiment. In the second embodiment, the turning angle controller 15 includes three turning motors 5a, 5b, and 5c. It consists of angle controllers 15a, 15b, 15c. In the third embodiment, motor temperature sensors (temperature detection means) 25a, 25b, and 25c that detect motor temperatures of the respective steering motors 5a, 5b, and 5c are provided.

  In the second embodiment, when there are three components of the motor drive control unit, the main is the motor drive control unit a, the sub motor drive control unit is the motor drive control unit b, the motor drive control unit c, and the motor relay diagnosis motor The drive control unit is b.

Next, the operation will be described.
[Motor relay diagnostic control processing]

  FIG. 8 is a flowchart showing the flow of the motor relay diagnosis control process executed by the turning angle controller 15 of the second embodiment. Each step will be described below. In addition, the same step number is attached | subjected to the step which performs the same process as Example 1 shown in FIG. 3, and description is abbreviate | omitted.

  In step S21, the steering state is acquired, and the process proceeds to step S22. As the steering state, information on the steering angle and steering angular velocity of the handle 1 is acquired.

In step S22, the steering state quantity obtained in step S 21 is, in the case which meet certain criteria with, to enable the motor relay diagnosis. If it is determined that the diagnosis is possible, the process proceeds to step S3. If it is determined that the diagnosis is impossible, the process proceeds to step S21.

  Here, the determination criteria for the motor relay diagnosis are as follows when any value indicating the vehicle behavior state such as the yaw rate or the lateral G has not reached the turning limit state before the start of the slip.

Start condition: Diagnosis starts when steering angular velocity exists.
During main switching, torque fluctuations of 1N or less may occur. Although it does not affect the vehicle behavior, the driver may feel uncomfortable through the steering wheel 1 even when the steering wheel 1 is in a neutral state or during steering, even when the steering wheel is 1N or less, but during steering, a torque fluctuation of 1N or more occurred. Even in this case, since the driver cannot recognize it due to the disturbance, even if main switching occurs during the motor relay diagnosis, there is no sense of incongruity. Therefore, when the steering angular velocity is larger than the value assumed during steering, the diagnosis is started.

In step S23, the motor drive control unit that performs the main ( performs calculation, distribution, and command of torque command values ) is determined from the motor drive control unit that is operating normally. In the second embodiment, since there are three components of the motor drive control unit, the main is the motor drive control unit a, the sub motor drive control unit is the motor drive control unit b, and the motor drive control unit c, and the motor relay diagnosis motor drive is performed. When the control unit is b, during motor relay diagnosis, the main motor drive control unit a calculates the torque command value from the distribution rate and the torque distribution change rate, and the motor drive control unit b and the motor drive control unit c Notice.

In a normal state, the main motor drive control unit calculates a torque command value for each motor drive control unit by the following calculation formula. As in the first embodiment, it is preferable to select the main motor drive control unit with the highest reliability depending on the heat load of the motor and the abnormality occurrence rate.
Torque command value = total torque command value / (number of motors that can be operated)
Or
Motor drive control unit a = total torque command value × distribution rate a
Motor drive control unit b = total torque command value × distribution rate b
Motor drive control unit c = total torque command value × distribution rate c

  Here, at the time of diagnosis of the motor drive control unit b, b = 0 is set so that a + c = 100%. The ratio of a and c is increased when the motor heat generation amount is smaller (the motor temperature is lower).

  Further, after step S5, the sub motor drive control unit c calculates a torque command value in step S13 separately from the command value of the main motor drive control unit a. When the main motor drive control unit a becomes abnormal, main switching occurs, the motor relay diagnosis continues, and the motor is driven using the torque command value calculated in step S13.

  During the motor relay diagnosis, the main motor drive control unit a calculates the command current value from the torque distribution ratio and notifies the motor drive control unit b and the motor drive control unit c, which are shown in the flowchart of the first embodiment. After step S5, the sub motor drive control unit c calculates the torque command value separately at step S13 separately from the torque command value of the main motor drive control unit.

When the main motor drive control unit is abnormal, the motor drive control unit c performs a motor drive using the torque command value calculated in step S 13. The motor drive control unit c continues the subsequent processing and operates as the main motor drive control unit when the motor drive control unit a which is the main motor drive control unit becomes abnormal, and thus continues the motor relay diagnosis. Can be done.

[Continuous motor relay diagnosis when main motor drive control unit fails]
In the second embodiment, three motor drive control units are provided, and even when a motor drive control unit other than the motor relay diagnosis motor drive control unit becomes abnormal, the remaining motor drive control unit distributes the total torque command value. Thus, the steering control is continued in the remaining motor drive control units without interrupting the motor relay diagnosis.

  That is, when three or more motor drive control units are provided, the steered motor of the motor drive control unit during motor relay diagnosis is in an inoperative state. For this reason, the system is operated by the remaining motor drive control units, but when there are three or more motor drive control units and an abnormality is detected in the remaining motor drive control units, distribution is performed by the remaining motor drive control units. This makes it possible to perform diagnosis without interrupting motor relay diagnosis.

This is because the remaining motor drive control unit determines the main motor drive control unit and the sub motor drive control unit, but the sub motor drive control unit also performs angle control calculation for the system in the same manner as the main motor drive control unit, and calculates the torque command value. To do. Thereby, even when the main motor drive control unit becomes abnormal, the motor drive control unit operating as the sub motor drive control unit is switched to the main motor drive control unit, and the system can be operated continuously.

[Torque distribution rate changing action according to motor heat generation]
In the second embodiment, the load on the motor is reduced by determining the distribution amount according to the motor heat generation amount. That is, each motor has a different location in the vehicle. Therefore, depending on the location of the motor, the amount of heat generated by the motor varies even when the distribution amount of the torque command value is uniform in a steady state. Therefore, by changing the distribution ratio of the total torque command value as a small distribution amount for motors with a large amount of heat generation and as a large distribution amount for motors with a small amount of heat generation, depending on the heat generation state of the motor, It is possible to reduce the load on the motor accompanying the relay diagnosis.

Next, the effect will be described.
In the vehicle steering control device according to the second embodiment, the following effects can be obtained.

  (6) Motor temperature sensors 25a, 25b, and 25c that detect the temperatures of the motors 5a and 5b, respectively, are provided, and the turning angle controller 15 reduces the torque distribution amount to the motor as the temperature of the motor to which torque is distributed is lower. Since the size is increased, the motor load associated with the motor relay diagnosis can be reduced.

  (7) The turning angle controller 15 generates a torque to be output by the failed motor when at least one of the undiagnosed motors fails during the interruption diagnosis by the motor relay diagnosis processing unit 18a (18b or 18c). Since the quantity is distributed to the motors that have not failed, the diagnosis can be performed without interrupting the motor relay diagnosis.

  The third embodiment is an example in which two steered motors and two motor drive control units are provided, and the diagnosis is stopped when an undiagnosed motor fails during the motor relay cutoff diagnosis. The configuration of the third embodiment is the same as that of the first embodiment shown in FIGS.

[Motor relay diagnosis stop action]
The steered motor of the motor drive control unit during motor relay diagnosis is in an inoperative state, and if the other motor fails in this state, steering is affected. Therefore, in the third embodiment, when a motor that is operating during diagnosis fails, the diagnosis is immediately stopped, and the torque generation amount of the failed motor is distributed to the motor that has been diagnosed. Control can be continued.

Next, the effect will be described.
In the vehicle steering control device according to the third embodiment, the following effects can be obtained.

  (8) The motor relay diagnosis processing units 18a and 18b stop the interruption diagnosis when an undiagnosed motor fails during the interruption diagnosis, and the turning angle controller 15 determines the torque generation amount of the failed motor. Since the motor is distributed to the diagnosed motor, the steering control can be continued without affecting the steering.

(Other examples)
As mentioned above, although the best form for implementing this invention was demonstrated based on Examples 1-3, the concrete structure of this invention is not limited to an Example, and does not deviate from the summary of invention. Any change in the design of the range is included in the present invention.

  For example, in the first to third embodiments, the relay provided between the motor driver and the power source has been described as the connecting / disconnecting means. However, it is sufficient that the torque of the motor can be held and cut off. May be provided. Further, a clutch may be provided in the motor rotation output to hold or cut off the motor torque.

  In the first to third embodiments, in the steer-by-wire system in which the handle 1 and the front wheels 4 and 4 are mechanically separated, the control of the steering motor that steers the front wheels 4 and 4 has been described. Can be applied to the control of an assist motor that assists the driver's steering force in a steering device in which the steering wheel 1 and the front wheels 4 and 4 are mechanically coupled. Further, the present invention can also be applied to a case where there are a plurality of steering reaction force motors that apply a steering reaction force torque to the steering shaft 7.

  In the second embodiment, an example in which the total torque command value is divided and distributed is shown. However, the total torque command value may be changed according to the motor temperature, for example. Alternatively, a large number of motor failure histories may be allocated to those with a low possibility of failure. Furthermore, it is good also as a structure which changes the amount of torque changes according to a vehicle speed, a steering angle, etc.

  In Examples 1-3, although the example which provided the steering motor in the steering shaft was shown, you may provide in the other site | part of a steering system, for example, a rack shaft etc.

1 is an overall configuration diagram illustrating a steer-by-wire system to which a vehicle steering apparatus according to a first embodiment is applied. FIG. 3 is a control block diagram illustrating a turning angle controller 15 according to the first embodiment. It is a flowchart which shows the flow of the motor relay diagnostic control process performed with the steering angle controller 15 of Example 1. FIG. It is a setting map of the correction gain G1 according to a yaw rate. It is a setting map of the correction gain G2 according to the horizontal G. It is a figure which shows the motor relay diagnostic effect | action of Example 1. FIG. It is a control block diagram which shows the turning angle controller 15 of Example 2. FIG. It is a flowchart which shows the flow of the motor relay diagnostic control process performed with the turning angle controller 15 of Example 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steering wheel 2 Steering reaction force motor 3 Steering part 4 Front wheel 5a, 5b Steering motor 6 Steering part 7 Steering shaft 8 Steering angle sensor 9 Torque sensor 10 Steering shaft 11 Steering gear mechanism 12 Tie rod 13 Steering reaction force controller 14 Steering controller 15a, 15b Steering angle controllers 16a, 16b Angle control calculation units 17a, 17b Current control calculation units 18a, 18b Motor relay diagnosis processing unit 19 Communication bus interface 20a, 20b Angle sensors 21a, 21b Current sensors 22a, 22b Motor driver 23 Power supply 24a, 24b Relay 30 Vehicle speed sensor 31 Yaw rate sensor 32 Lateral G sensor

Claims (8)

At least one of the steering mechanism that applies steering torque to the steering wheel and the reaction force mechanism that adds reaction force torque to the steering wheel has a plurality of torque generating means for generating torque with electric power from the power source. ,
Torque control means for controlling the amount of torque generated by the plurality of torque generating means;
A plurality of connecting / disconnecting means respectively provided corresponding to the plurality of torque generating means so as to hold or cut off power supply from the power source to each of the plurality of torque generating means ;
Blocking diagnostic means for diagnosing whether one of the plurality of connecting / disconnecting means can be blocked, and
With
The torque control unit divides a total torque command value and distributes the total torque command value to each of the plurality of torque generation units, and controls a torque generation amount of each of the plurality of torque generation units based on the distributed torque command value. Because
The blocking diagnostic means by that diagnosis Sometimes, the torque control means, the zero torque command value to be distributed to the torque generating means corresponding to the engaging and disengaging means for said shut-off diagnosis means diagnoses of the plurality of disconnection device The vehicle steering control device is characterized in that the torque command value distributed to the torque generating means corresponding to the connecting / disconnecting means not diagnosed by the shutoff diagnostic means is increased more than before the diagnosis is started by the shutoff diagnostic means. . The vehicle steering control device according to claim 1,
The torque control means increases a torque command value distributed to a torque generation means corresponding to a connection / disconnection means that is not diagnosed by the interruption diagnosis means among the plurality of connection / disconnection means than before the diagnosis start by the interruption diagnosis means. A vehicle steering control device characterized in that the rate of increase decreases as the amount increases . The vehicle steering control device according to claim 1 or 2,
Comprising a vehicle behavior state variable detection means for detecting a yaw rate or lateral acceleration of the vehicle as a vehicle both ani dynamic state quantity,
As the vehicle behavior state quantity is larger, the torque control means outputs a torque command value to be distributed to the torque generating means corresponding to the connection / disconnection means diagnosed by the interruption diagnosis means among the plurality of connection / disconnection means. The torque command value to be distributed to the torque generating means corresponding to the connection / disconnection means not diagnosed by the shutoff diagnosis means is reduced while reducing the rate of change of the torque command value when the value is reduced to zero equivalent from the value before the diagnosis start by the means. A steering control device for a vehicle, wherein a rate of change of a torque command value when increasing from a value before starting diagnosis by a shutoff diagnostic means is reduced. The vehicle steering control device according to any one of claims 1 to 3,
Providing temperature detecting means for detecting the temperature of each of the plurality of torque generating means;
The torque control means reduces the torque command value to be distributed to the torque generating means as the temperature of the torque generating means corresponding to the connecting / disconnecting means not diagnosed by the shutoff diagnosing means of the plurality of connecting / disconnecting means decreases. A vehicle steering control device characterized in that the amount of increase is larger than that before the diagnosis is started by the diagnosis means . The vehicle steering control device according to any one of claims 1 to 4,
It said torque control means, in diagnostics that by the said shut-off diagnosis means, wherein at least one of the torque generating means the blocking diagnosis unit corresponds to a disengaging means not diagnostic of a plurality of disconnection device is faulty when the failure was a torque command value that has been distributed to the torque generating means, the steering control apparatus for a vehicle, characterized in that to distribute the torque generating means not failure. The vehicle steering control device according to any one of claims 1 to 5,
During diagnostics by the blocking diagnosis means, wherein when the interrupting diagnosis means is defective, all the torque generating means corresponding to the engaging and disengaging means not diagnosed, said blocking means for diagnosing diagnoses of the plurality of disconnection device The torque control means distributes the torque command value distributed to the failed torque generation means to the torque generation means corresponding to the connection / disconnection means diagnosed by the shutoff diagnosis means. A vehicle steering control device. The vehicle steering control device according to any one of claims 1 to 6,
The increased value of the torque command value calculated by the torque control unit and distributed to the torque generation unit corresponding to the connection / disconnection unit that is not diagnosed by the disconnection diagnosis unit among the plurality of connection / disconnection units is greater than or equal to a predetermined value. In the vehicle steering control device, the shut-off diagnosis means does not perform diagnosis. The vehicle steering control device according to any one of claims 1 to 7,
A turning limit determining means for determining a turning limit of the vehicle ;
When in the prior SL turning limit, vehicle steering control apparatus, characterized in that the blocking diagnosis means does not perform the diagnosis.

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