JP4089283B2 - Motor control device for electric power steering device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a motor control device for an electric power steering apparatus that detects a steering torque applied to a steering wheel by a torque sensor and controls assist torque supplied by an electric motor based on the detected torque value.
[0002]
[Prior art]
Conventionally, in an electric power steering device that assists steering with respect to a steering wheel by the power of an electric motor, for example, a steering assist that controls an assist torque of a motor based on a steering torque detected by a torque sensor and a vehicle speed detected by a vehicle speed sensor. Control is performed.
[0003]
In this steering assist control, an assist torque is set based on the steering torque and the vehicle speed, and the motor is feedback-controlled so as to generate the assist torque.
[0004]
The assist torque is set to have the same magnitude with respect to the same steering torque value Ts1 during right steering and during left steering as indicated by a two-dot chain line in FIG. 5 for a certain vehicle speed.
[0005]
  Therefore, as indicated by a two-dot chain line in FIG. 6, the value (absolute value) of the steering torque Ts required for the same steering steering angle value θ1 during right steering and left steering while the vehicle is running. Are equal. This steering torque-steering angle characteristic is applied to the steered wheels.Self-aligning torqueWhen a vehicle is traveling at a certain vehicle speed, it acts on the steering wheel for a certain steering angle value θ1.Self-aligning torqueThe steering torque Ts required for the reverse steering force based on is shown.
[0006]
[Problems to be solved by the invention]
However, as indicated by the solid line in FIG. 4, there is an offset error in the actual torque sensor, and there is a difference in the output value for the same steering torque value Ts1 during right steering and during left steering. In addition, the offset error varies among sensors, and drifts with a temperature change.
[0007]
When a torque sensor having an offset error is used in this way, as shown by a solid line in FIG. 5, the assist torque Ta generated for the same steering torque value Ts1 during right steering and during left steering is obtained. A difference occurs.
[0008]
As a result, as shown in FIG. 7, in the traveling vehicle, there is a difference in the value of the steering torque Ts that is necessary for the same steering steering angle θ between the right steering and the left steering. It will give you a sense of incongruity.
[0009]
The present invention has been made to solve the above-described problems, and its object is to drive even when there is an offset error in the steering torque detected by the torque sensor at the time of right steering and left steering of the steering wheel. It is an object of the present invention to provide a motor control device for an electric power steering device that can make it difficult for a difference in steering torque in a vehicle during left and right steering to occur.
[0010]
[Means for Solving the Problems]
  In order to solve the above problems, the invention according to claim 1In the motor control device of the electric power steering device that controls the assist torque generated by the electric motor using the detection value of the torque sensor that detects the steering torque applied to the steering wheel, the steering steering angle is self-adjusted to the steering wheel. Steering angle determination means for determining whether or not a neutral steering state in which the lining torque does not substantially work, vehicle speed determination means for determining whether or not the vehicle speed is in a vehicle speed range in which self-aligning torque is applied to the steered wheels, Steering direction determination means for determining whether or not the steering wheel is being steered to the right or left, and when the steering wheel is steered to the right when the vehicle speed is in the vehicle speed range. The detected value of the steering torque in the right steering state in the neutral steering state and the neutral steering when the left steering is performed at a steering angular velocity substantially equal to the right steering. With a correction value acquisition means for obtaining an intermediate value between the left steering when the detected value of the steering torque at the state, and correcting means for correcting the detected value of the steering torque of the intermediate value as an offset error of the steering torque,
The correction value acquisition means determines whether the steering angular speed of the steering wheel is within a steering angular speed range in which the steering reaction force generated by the steering is generated only by the frictional resistance of the steering system. And a right steering detected value of the steering torque in the neutral steering state when the right steering is performed at the steering angular velocity in the steering angular velocity region, and a neutral steering state when the left steering is performed at the steering angular velocity in the steering angular velocity region. And an intermediate value acquisition means for obtaining an intermediate value of the steering torque at the left steering detection value, and the assist torque is controlled using the corrected torque detection value corrected by the correction means.
[0011]
According to the first aspect of the present invention, when the vehicle speed of the traveling vehicle is in a vehicle speed range where the self-aligning torque is applied to the steering wheel, the steering torque necessary for steering the steering wheel is reversed by the self-alignment torque. In addition to the steering force, the steering reaction force is generated opposite to the steering reaction force due to the frictional resistance of the steering system, and further to the steering reaction force due to the viscous resistance of the steering system. On the other hand, when the vehicle is in a vehicle speed range where the self-alignment torque does not substantially work or the vehicle is stopped, the steering torque is a steering reaction force caused by a frictional resistance of a steering system, Further, it is generated against the steering reaction force due to the viscous resistance of the steering system.
[0012]
Even in the vehicle speed range where the self-alignment torque acts on the steered wheels, the steering torque when the steering angle is in a neutral steering state where the self-alignment torque hardly acts on the steered wheels is the steering reaction force due to the frictional resistance of the steering system, It is generated opposite to the steering reaction force due to the viscous resistance of the steering system. Furthermore, the frictional resistance of the steering system is due to static friction that acts when the steering wheel is not being steered, and due to motion friction that acts when the steering wheel is being steered. The frictional resistance due to static friction changes in magnitude according to the steering torque actually applied to the steering wheel, and the frictional resistance due to motion friction has a substantially constant magnitude regardless of the steering angular velocity. The viscous resistance acts when the steering wheel is steered, but is sufficiently smaller than the frictional resistance in a predetermined region where the steering angular velocity is low, but the steering reaction force is increased along with the frictional resistance as the steering angular velocity increases. Generate.
[0013]
When the steering wheel is steered in a predetermined steering angular velocity range in which this frictional resistance is generated only by motion friction, the steering torque in the neutral steering state is substantially equal during right steering and during left steering. In addition, although the magnitude of the steering reaction force due to the viscous resistance changes according to the steering angular speed of the steering wheel, when the steering angular speeds of the right steering and the left steering are substantially equal, the steering torque in the neutral steering state is And at the time of left steering. Also, when the vehicle is in a vehicle speed range where the self-alignment torque does not work or when the vehicle is stopped, the steering torque in the neutral steering state when the steering angle is steered depends on the steering angular velocity at that time. Different sizes. For this reason, when there is no offset error in the torque sensor, the detected value of the steering torque in the neutral steering state during both the right steering and the left steering when the vehicle is traveling at the vehicle speed at which the self-alignment torque is applied to the steered wheels. Are almost equal.
[0014]
On the other hand, if there is an offset error in the torque sensor, the detected values of the two steering torques in the neutral steering state are shifted together by an amount corresponding to the offset error. At this time, if one of the right steering detection value of the steering torque during right steering and the left steering detection value of the left steering torque increases by an offset error, the other of the two detection values is the offset error. Get smaller.
[0015]
For this reason, the intermediate value of the detected values of both the steering torques in the neutral steering state during the right steering and the left steering corresponds to the offset error of the steering torque corresponding to the offset error of the torque sensor. Accordingly, when the detected value of the steering torque is corrected using the obtained offset error, the offset error of the steering torque based on the offset error of the torque sensor is removed.
[0018]
  or,Claim1According to the invention described in, ManipulationTo the helmSelf-aligning torqueWhen the steering wheel is steered at a steering angular velocity in a predetermined steering angular velocity range in which the steering reaction force is substantially caused by the frictional resistance of the steering system when the vehicle is in a vehicle speed range where the vehicle does not substantially work, steering by the frictional resistance in the neutral steering state The reaction force is substantially equal between right steering and left steering. For this reason, even if the steering angular velocity at the time of right steering and the steering angular velocity at the time of left steering are not substantially equal, the steering torque in the neutral steering state is substantially equal if both are within a predetermined steering angular velocity range. Therefore, the opportunity to acquire the detected value of the steering torque in the neutral steering state at the time of right steering and left steering is expanded, so that the offset error of the steering torque based on the offset error of the torque sensor can be acquired more quickly. .
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment in which the present invention is embodied in a column assist type electric power steering apparatus will be described with reference to FIGS.
[0022]
As shown in FIG. 2, the electric power steering device 10 includes a motor control device 11, a motor drive device 12, an electric motor (hereinafter abbreviated as a motor) 13, a torque sensor 14, a vehicle speed sensor 15, a steering angle sensor 16, It is comprised by the current sensor 17 grade | etc.,. In the present embodiment, the motor control device 11 is a steering angle determination unit, a vehicle speed determination unit, a steering direction determination unit, a correction value acquisition unit, a correction unit, a steering angular velocity determination unit, and an intermediate value acquisition unit.
[0023]
The torque sensor 14 detects the steering torque Ts applied to the steering wheel 20 from the torsion of the torsion bar 19 provided on the steering shaft 18 and outputs it to the motor control device 11. As indicated by a two-dot chain line in FIG. 4, the torque sensor 14 outputs a voltage signal that is substantially directly proportional to the steering torque Ts applied to the steering wheel 20 in accordance with right steering and left steering.
[0024]
The vehicle speed sensor 15 detects the vehicle speed V from the rotation of the front wheel 28 and outputs it to the motor control device 11. The steering angle sensor 16 detects the steering angle θ of the steering wheel 20 and outputs it to the motor control device 11. The current sensor 17 detects a motor current Id that changes according to the operating state of the motor 13 and outputs it to the motor control device 11.
[0025]
The motor control device 11 includes a microcomputer, generates a motor control signal Im based on the steering torque Ts, the vehicle speed V, the steering angle θ, and the motor current Id, and outputs the motor control signal Im to the motor drive device 12.
[0026]
The motor drive device 12 drives and controls the motor 13 based on the motor control signal Im.
The motor 13 drives a reduction gear 21 fixed to the steering shaft 18 with a drive gear 22 fixed to the rotating shaft. When the steering shaft 18 rotates as the steering wheel 20 is steered, the pinion shaft 23 fixed to the reduction gear 21 rotates integrally, and the pinion gear 24 fixed to the tip of the pinion shaft 23 operates the rack 25. The rack 25 rotates the knuckle 27 via the tie rod 26 and steers the front wheel 28 supported by the knuckle 27.
[0027]
When the motor 13 rotates, the rotation is transmitted to the pinion shaft 23 via the reduction gear 21 and is transmitted to the rack 25 via the pinion gear 24.
When the motor 13 is operated when the steering wheel 20 is steered, the front wheels 28 are steered by the steering force by the assist torque supplied by the motor 13 in addition to the steering force by the steering torque Ts applied to the steering wheel 20. The
[0028]
Next, the motor control device 11 will be described with reference to the block diagram of FIG.
The motor control device 11 includes a torque correction unit 30, an assist torque calculation unit 31, a command current setting unit 32, a torque control unit 33, a motor control unit 34, a subtraction unit 35, and the like. Among these, the torque correction unit 30 is a novel component of the present invention, but the remaining components excluding the torque correction unit 30 are known.
[0029]
The torque correction unit 30 generates a corrected steering torque (corrected torque detection value) Ts * obtained by correcting the steering torque Ts detected by the torque sensor 14 based on the vehicle speed V and the steering angle θ. The corrected steering torque Ts * is obtained by removing the offset error of the torque sensor 14 from the steering torque Ts. The torque correction unit 30 will be described in detail later.
[0030]
The assist torque calculator 31 obtains an assist torque (target assist torque) Ta based on the corrected steering torque Ts * and the vehicle speed V. The assist torque Ta is set according to the vehicle speed V, and gradually increases as the steering torque Ts accompanying the right steering or the left steering increases with respect to a certain vehicle speed V as shown in FIG. Is set. Also, for a certain vehicle speed V, the same assist torque Ta is set for the same steering torque Ts during right steering and during left steering.
[0031]
The command current setting unit 32 sets the command motor current Im * based on the assist torque Ta.
The subtracting unit 35 obtains a current difference value ΔIm between the command motor current Im * and the motor current Id.
[0032]
Based on the current difference value ΔIm, the torque control unit 33 generates a motor voltage signal Vm so that the motor current Id approaches the command motor current Im * by known feedback control such as PI control.
[0033]
The motor control unit 34 generates a motor control signal Im based on the motor voltage signal Vm and outputs it to the motor drive device 12.
The motor control device 11 configured as described above performs steering assist control for controlling the torque generated by the motor 13 to the assist torque Ta based on the steering torque Ts and the vehicle speed V.
[0034]
With this steering assist control, in a vehicle traveling at a vehicle speed V at which self-aligning torque is applied to the front wheels 28, the steering torque Ts with respect to the steering angle θ changes as shown by a two-dot chain line in FIG.
[0035]
This is because the steering wheel 20 out of the total steering force that balances the reverse steering force based on the self-aligning torque applied to the front wheel 28 in a steered state with a magnitude corresponding to the front wheel steering angle (slip angle) during traveling of the vehicle. The relationship between the steering torque Ts applied to the steering angle θ is shown.
[0036]
  Self-aligning torqueIndicates a characteristic that increases as the steering angle θ increases. Therefore, as shown in FIG. 5, the steering torque Ts changes as the steering steering angle θ approaches “0” as a result of the assist torque Ta set with respect to the steering torque Ts. As θ (absolute value) is larger, the characteristic changes smaller.
[0037]
  Actually, this steering torque-steering steering angle characteristic has hysteresis based on the static frictional force of the steering system, as shown by the solid line in FIG. That is, as the steering wheel 20 is steered, a steering reaction force in the direction opposite to the steering is generated by the frictional resistance of the steering system, and a steering torque Ts for the frictional resistance is generated. As a result, the steering angle θ is a neutral steering state in which the slip angle of the front wheels 28 is substantially “0”.Self-aligning torqueEven when the vehicle does not act on the front wheel 28, the steering torque Ts is required in the neutral steering state along with the right steering and the left steering.
The steering torque Ts in this neutral steering state is substantially equal during right steering and left steering. This is because the friction resistance of the steering system is substantially equal during right steering and left steering.
[0038]
  It works on the front wheel 28Self-aligning torqueIn a vehicle that is traveling at a vehicle speed V that is sufficiently smaller than the frictional resistance of the steering system or a vehicle that is stopped, the characteristic of the steering torque Ts with respect to the steering angle θ is shown in FIG. It is almost constant regardless of the steering angle θ. This is because the steering reaction force generated when the steering wheel 20 is steered is substantially caused by frictional resistance with the road surface, and this frictional resistance is substantially constant regardless of the steering angle θ. In this state, when the steering wheel 20 is steered from a certain steering angle θ, the steering torque Ts rises from “0” regardless of the steering angle θ as shown in FIG. Therefore, the steering torque Ts when the steering angle θ is “0” takes different values depending on the steering angle θ at which the steering is started.
[0039]
Further, the steering torque-steering steering angle characteristic has hysteresis based on viscous resistance of a steering system grease or the like, as indicated by a broken line in FIG. Unlike the hysteresis based on frictional resistance, this hysteresis increases as the steering angular velocity of the steering wheel 20 increases.
[0040]
Here, if there is an offset error in the torque sensor 14, for example, as indicated by a solid line in FIG. For this reason, the relationship of the assist torque Ta generated with respect to the steering torque Ts is biased as shown by a solid line in FIG. 5, and the right steering is set to the value of the assist torque Ta generated with respect to the same steering torque value Ts1. There is a difference between the hour and left steering.
[0041]
As a result, as shown in FIG. 7, the steering torque-steering angle characteristic is biased, and the difference in steering torque Ts required for the same steering steering angle value θ1 is different between right steering and left steering. it can.
[0042]
The torque correction unit 30 detects the right steering detection value of the steering torque Ts in the neutral steering state when the steering wheel 20 is steered to the right, and the steering torque Ts in the neutral steering state when the steering wheel 20 is steered to the left. The average value (intermediate value) with the left steering detection value is obtained. Then, the detected value of the steering torque Ts is corrected using the average value as an offset error of the steering torque.
[0043]
Based on the steering angle θ and the vehicle speed V, the torque correction unit 30 determines whether or not the steering reaction force generated when the steering wheel 20 is steered is in a steering angular velocity region that is generated only by the frictional resistance of the steering system. Determine. And the detected value at the time of the right steering of the steering torque Ts in the neutral steering state when the right steering is performed in the range of the steering angular velocity range, and the neutral steering state when the left steering is performed in the same range of the steering angular velocity range. An average value of the steering torque Ts and the detected value at the time of left steering is obtained.
[0044]
Next, a steering torque correction process performed by the motor control device 11 as the torque correction unit 30 will be described in detail.
In the steering torque correction process, as shown in FIG. 1, first, in S100, a low-pass filter (LPF) process is performed using the following equation (1) on the torque detection value Tsp of the steering torque Ts detected by the torque sensor 14, A post-LPF correction torque value Tn from which noise is removed is obtained.
[0045]
Tn = Tsp · α + (1−α) T (n−1) (1)
T (n-1): Post-LPF corrected torque value obtained in the previous process
α: LPF time constant
Next, in S101, the steering steering angle θ at that time is within the range of the neutral steering state in the range of −5 ° <θ <+ 5 ° in which substantially no self-aligning torque acts on the front wheels 28 while the vehicle is traveling. It is determined whether or not. The range of the neutral steering state is not limited to −5 ° <θ <+ 5 °, and may be a narrower range of ± 2 or ± 3, for example.
[0046]
If an affirmative determination is made in S101, then in S102, whether or not the vehicle speed V at that time exceeds the vehicle speed range up to 20 km / h where the self-aligning torque does not substantially act on the front wheels 28 regardless of the steering angle θ. judge.
[0047]
  If an affirmative determination is made in S102, then in S103, the steering direction and the steering angular velocity ω are obtained from the rate of change of the steering angle θ, and the steering wheel 20 is 1 rad / sec. <Ω <1.5 rad / sec. It is determined whether the vehicle is steered to the right at a steering angular velocity ω within the steering angular velocity range. This steering angular velocity range is a range in which the steering reaction force generated with the steering of the steering wheel 20 is generated only by the frictional resistance of the steering system. In this steering angular velocity range, the behavior of the vehicle is settled, and the steering reaction force in the neutral steering state isSelf-aligning torqueIt will not depend on.
[0048]
If an affirmative determination is made in S103, then in S104, a right steering neutral torque value (right steering detected value) Tr obtained by smoothing the post-LPF correction torque value Tn is obtained using the following equation (2), and then S107 Execute.
[0049]
          Tr = β · Tn + (1−β) · T (r−1) (2)
                          T (r-1): previous right steering neutral torque value
                          β: Forgetting factor
  The vehicle speed V is changed to the front wheel 28 by the processing of S100 to S104.Self-aligning torqueThe right steering neutral torque value Tr of the steering torque Ts in the neutral steering state when the steering wheel 20 is steered to the right is obtained in the driving state of the vehicle in which the vehicle speed region is working. The right steering neutral torque value Tr is a detected value of the steering torque Ts with respect to the steering reaction force generated almost only by the friction resistance of the steering system in the neutral steering state during the right steering.
[0050]
On the other hand, if a negative determination is made in S103, then in S105, the steering direction and the steering angular velocity ω are obtained from the rate of change of the steering angle θ, and the steering wheel 20 is 1 rad / sec. <Ω <1.5 rad / sec. It is determined whether left steering is performed at a steering angular velocity ω within the steering angular velocity range.
[0051]
If the determination in S105 is affirmative, then in S106, a left steering neutral torque value (detected value during left steering) Tl obtained by smoothing the post-LPF correction torque value Tn using the following equation (3) is obtained, and then S107 Execute.
[0052]
          Tl = β · Tn + (1−β) · T (l−1) (2)
                          T (l-1): last left steering neutral torque value
                          β: Forgetting factor
  By the processing of S100 to S102, S105, and S106, the vehicle speed V is changed to the front wheel 28.Self-aligning torqueThe left steering neutral torque value Tl of the steering torque Ts in the neutral steering state when the steering wheel 20 is steered to the left is obtained in the driving state of the vehicle in the vehicle speed range in which. The left steering neutral torque value Tl is a detected value of the steering torque Ts with respect to the steering reaction force generated only by the frictional resistance of the steering system in the neutral steering state during left steering.
[0053]
In S107, the left and right average torque value (intermediate value) Tm of the right steering neutral torque value Tr and the left steering neutral torque value Tl is obtained as in the following equation (4).
Tm = (Tr + Tl) / 2 (4)
In S108 after S107, a torque offset value Tos obtained by smoothing the left and right average torque value Tm is obtained using the following equation (5).
[0054]
Tos = γ · Tm + (1−γ) T (os−1) (5)
T (os-1): previous torque offset value
γ: Forgetting factor
The torque offset value Tos obtained from the right and left average torque values Tm of the right steering neutral torque value Tr and the left steering neutral torque value Tl by the processing of S107 and S108 is set as an offset error of the steering torque Ts.
[0055]
Following S108, in S109, a corrected steering torque Ts * obtained by adding the torque offset value Tos to the torque detection value Tsp is obtained as in the following equation (6).
Ts * = Tsp + Tos (6)
Next, effects of the present embodiment described in detail above will be listed.
[0056]
  (1) Front wheel 28Self-aligning torqueWhen the steering wheel 20 is steered right and left in a vehicle traveling at a vehicle speed V at whichSelf-aligning torqueTorque detection values Tsp (right steering neutral torque value Tr, left steering neutral torque value Tl) of the steering torque Ts in the neutral steering state where the engine does not operate are respectively acquired.
Each steering torque Ts at this time has a necessary magnitude with respect to the steering reaction force generated only by the frictional resistance of the steering system.
[0057]
A left-right average torque value (intermediate value) Tm of the detected values of both steering torques Ts is obtained, and a torque detection value of the steering torque Ts is obtained by using a value obtained by smoothing the left-right average torque value Tm as a torque offset value (offset error) Tos. Tsp is corrected.
[0058]
The assist torque Ta of the motor 13 is controlled based on the corrected steering torque Ts *.
As a result, even when there is an offset error in the steering torque Ts detected by the torque sensor 14 during the right steering and the left steering of the steering wheel 20, it is unlikely that a difference occurs in the steering torque Ts in the traveling vehicle during left and right steering. Can be. Therefore, for example, it is difficult to give the driver an uncomfortable feeling during steering.
[0059]
(2) The steering angular velocity ω of the steering wheel 20 is detected to be within the range of the steering angular velocity range in which the steering reaction force generated along with the steering is generated only by the frictional resistance of the steering system. The left and right sides of the detected torque value Tsp (the right steering neutral torque value Tr and the left steering neutral torque value Tl) in the neutral steering state when the steering wheel 20 is steered right and left in this steering angular velocity range. The average torque value Tm was obtained.
[0060]
For this reason, even if there is a difference in the steering angular velocity ω between the right steering and the left steering in the neutral steering state, the actual steering torque Ts in the neutral steering state is as long as both are within the predetermined steering angular velocity range. Almost equal.
[0061]
Therefore, the opportunity to acquire the torque detection value Tsp in the neutral steering state at the time of right steering and left steering is expanded, so that the offset error of the steering torque Ts based on the offset error of the torque sensor 14 can be eliminated more quickly. .
[0062]
  (3) The steering angle θ is in a neutral steering state, andSelf-aligning torqueEach time the condition that the vehicle speed range that can act on the front wheels 28 is satisfied, a new left-right average torque value Tm and a torque are further obtained from the torque detection value Tsp of the steering torque Ts in the neutral steering state at the time of right steering and left steering. The offset value Tos was obtained sequentially. Then, the detected torque value Tsp is corrected using the newly obtained torque offset value Tos. Therefore, during traveling of the vehicle, the torque offset value Tos of the steering torque Ts corresponding to the offset error of the torque sensor 14 at that time is acquired, and the torque detection value Tsp is corrected using this new torque offset value Tos. .
[0063]
Accordingly, even if there is a temperature drift in the offset error of the torque sensor 14, it is possible to make it difficult for the steering torque Ts in the traveling vehicle to be different during left and right steering.
[0064]
Next, embodiments other than the one embodiment will be listed.
In the embodiment, the neutral torque correction process performed by the motor control device 11 as the torque correction unit 30 is performed using a fixed torque offset value Tos preset for each individual torque sensor 14. 14 is a processing content for correcting the detected value of the steering torque Ts output by the engine 14. In this case, in addition to the effects described in (1) and (2) of the embodiment, when the temperature drift of the offset error of the torque sensor 14 is not so large, the steering torque Ts with respect to the steering angle θ is It is possible to make it difficult for a difference to occur between right steering and left steering.
[0065]
In the neutral torque correction process according to the embodiment, the steering angular velocity ω when the steering wheel 20 is steered to the right or left is used for lubrication in addition to the steering reaction force generated by the steering in addition to the frictional resistance of the steering system. It is determined whether or not the steering angular velocity region is also generated by the viscous resistance of the steering system due to grease or the like. When the steering angular velocity ω is within the range of the steering angular velocity range, the right steering neutral torque value Tr or the left steering neutral torque value Tl is generated according to the steering direction. Next, the right steering neutral torque value Tr or the left steering neutral torque value Tl is generated from the detected value of the steering torque Ts in the neutral steering state when steering in the reverse direction at the steering angular speed ω equal to the steering angular speed ω. . Then, a right / left average torque value Tm and a torque offset value Tos are generated from the right steering neutral torque value Tr and the left steering neutral torque value Tl that are generated when the right steering and the left steering are performed at the same steering angular velocity ω. In the case of such a configuration, there are the effects described in (1) and (2) of the embodiment.
[0066]
In the embodiment, the steering wheel 20 may acquire a neutral steering state, a steering direction, and a steering angular velocity from detection values of a steering angle sensor that detects the steering angle of the front wheels 28.
[0067]
In the embodiment, the motor control device 11 calculates the vehicle speed from the vehicle acceleration detected by the acceleration sensor.
The form of the electric power steering device embodying the present invention is not limited to the column assist type, but may be a rack assist type or a pinion assist type.
[0072]
【The invention's effect】
  Claim1According to the described invention, even when there is an offset error in the steering torque detected by the torque sensor during the right steering and the left steering of the steering wheel, it is difficult for a difference in steering torque in the traveling vehicle during left and right steering. Can be.
According to the first aspect of the present invention, when the vehicle is in a vehicle speed range where the self-aligning torque does not substantially act on the steered wheels, the steering reaction force is approximately in a predetermined steering angular velocity range where the steering reaction force is caused by frictional resistance of the steering system. When the steering wheel is steered at the steering angular velocity, the steering reaction force due to the frictional resistance in the neutral steering state is substantially equal between right steering and left steering. For this reason, even if the steering angular velocity at the time of right steering and the steering angular velocity at the time of left steering are not substantially equal, the steering torque in the neutral steering state is substantially equal if both are within a predetermined steering angular velocity range. Therefore, the opportunity to acquire the detected value of the steering torque in the neutral steering state at the time of right steering and left steering is expanded, so that the offset error of the steering torque based on the offset error of the torque sensor can be acquired more quickly. .
[Brief description of the drawings]
FIG. 1 is a flowchart showing a steering torque correction process performed by a motor control device of an electric power steering apparatus according to an embodiment.
FIG. 2 is a schematic configuration diagram showing an electric power steering apparatus.
FIG. 3 is a block diagram of a motor control device.
FIG. 4 is a graph showing an output-steering torque characteristic of a torque sensor.
FIG. 5 is a graph showing assist torque-steering torque characteristics.
FIG. 6 is a graph showing a steering torque-steering steering angle characteristic.
FIG. 7 is a graph showing a steering torque-steering steering angle characteristic.
FIG. 8 is a graph showing a steering torque-steering steering angle characteristic.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Electric power steering apparatus, 11 ... Steering angle determination means, vehicle speed determination means, steering direction determination means, correction value acquisition means, correction means, steering angular velocity determination means, and intermediate value acquisition means, 13 ... Electric motor , 14 ... Torque sensor, 15 ... Vehicle speed sensor, 16 ... Steering angle sensor, 20 ... Steering wheel, 28 ... Front wheel as steering wheel, 30 ... Torque correction unit, Ta ... Assist torque, Tm ... Left and right average torque as intermediate value Value, Tl: left steering neutral torque value as a detected value during left steering, Tr: right steering neutral torque value as a detected value during right steering, Ts: steering torque, Ts *: corrected steering torque as a corrected torque detected value, V: vehicle speed, θ: steering steering angle, ω: steering angular speed.

Claims (1)

In a motor control device of an electric power steering device that controls an assist torque generated by an electric motor using a detection value of a torque sensor that detects a steering torque applied to a steering wheel .
Steering angle determination means for determining whether or not the steering angle is a neutral steering state in which self-aligning torque does not substantially act on the steering wheel;
Vehicle speed determining means for determining whether or not the vehicle speed is in a vehicle speed range in which self-aligning torque is applied to the steered wheels;
Steering direction determination means for determining whether the steering wheel is steering right or steering left;
When the vehicle speed is in the vehicle speed range, the detected value at the time of right steering of the steering torque in the neutral steering state when the steering wheel is steered to the right, and the neutral when the steering wheel is steered to the left at a steering angular velocity substantially equal to the right steering Correction value acquisition means for obtaining an intermediate value between the detected value of the steering torque in the steering state and the left steering time;
Correction means for correcting the detected value of the steering torque using the intermediate value as an offset error of the steering torque,
The correction value acquisition means includes
Steering angular velocity determination means for determining whether or not the steering angular velocity of the steering wheel is a steering angular velocity region in which a steering reaction force generated by steering is substantially generated only by a frictional resistance of the steering system; Left steering of the steering torque in the neutral steering state when the left steering is performed at the steering angular velocity in the steering angular velocity range, and the detected value at the time of the right steering of the steering torque in the neutral steering state when the right steering is performed at the steering angular velocity It consists of an intermediate value acquisition means for obtaining an intermediate value with the hour detection value,
A motor control device for an electric power steering device, wherein the assist torque is controlled using a correction torque detection value corrected by the correction means .

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