JP2010254096A - Electric power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric power steering device which does not give a driver an uncomfortable feeling, in the correction of control carried out according to a detection value of a vehicle behavior sensor. <P>SOLUTION: A basic control portion 51 of an EPS_ECU20 of an electric power steering device calculates an assist current Ia on the basis of steering torque T<SB>rq</SB>. A yaw rate reaction force correcting current computing portion 65 calculates a yaw rate reaction force correcting current Iy for controlling steering reaction force components of steering assisting force on the basis of a yaw rate γ<SP>*</SP>. The yaw rate reaction force controlling portion 66 puts out a yaw rate reaction force correcting current Iy<SP>*</SP>corrected by adjusting the yaw rate reaction force correcting current Iy according to the difference between yaw rate sensor temperature T<SB>Y</SB><SP>*</SP>when learning a middle point and present yaw rate sensor temperature T<SB>Y</SB>, to a subtractor 53. The subtractor 53 subtracts the yaw rate reaction force correcting current Iy<SP>*</SP>corrected from the assist current Ia, and puts out that to a driving current control portion 54 as a target current It. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electric power steering apparatus including a vehicle behavior sensor that detects the behavior of a vehicle.

A vehicle equipped with an electric power steering device (EPS) that reduces a driver's steering force is known. Such a vehicle includes an EPS_ECU (Electronic Control Unit) for controlling the electric power steering device. Is equipped.
Further, when a vehicle stability Assist (VSA) function for controlling vehicle behavior is provided by combining ABS (Anti Lock Brake System) and TCS (Traction Control System), the vehicle has a VSA_ECU for controlling the behavior of the vehicle. It is equipped.

The EPS_ECU controls the electric power steering device in accordance with the behavior of the vehicle such as the vehicle running state (turning, straight traveling) and the vehicle speed, and generates steering assist force to reduce the steering force of the driver and the steering handle. Control to apply reaction force to the operation direction.
Therefore, a vehicle including an electric power steering device has a vehicle behavior detection system including a vehicle behavior sensor that detects the behavior of the vehicle. The vehicle behavior detection system includes a yaw rate sensor (corresponding to the “vehicle behavior sensor” in the present invention), a rudder angle sensor, a lateral acceleration sensor, a longitudinal acceleration sensor, etc. as a vehicle behavior sensor in order to detect turning of the vehicle. It is equipped.

As the rudder angle sensor, a sensor (for example, a rotary encoder) that uses a relative angle change amount of the steering handle as a detection value may be used. In this case, the EPS_ECU can calculate the steering angle of the steering handle based on the amount of change in angle from the reference point, for example, with the steering handle in the neutral position (hereinafter referred to as the steering angle midpoint).
Therefore, the EPS_ECU needs to learn the steering angle midpoint as the reference point. The yaw rate detected by the yaw rate sensor is used for learning the steering angle midpoint.
In order to improve the learning accuracy of the steering angle midpoint, the yaw rate sensor is required to detect the yaw rate with high accuracy.

  Some yaw rate sensors use a semiconductor element as described in Patent Document 1, and such a yaw rate sensor has a characteristic that a variation in a detected value accompanying a temperature change is large. Since the temperature of the yaw rate sensor changes sequentially as the vehicle travels, in order to accurately detect the yaw rate of the running vehicle, the middle point of the yaw rate sensor when the vehicle is not turning and the yaw rate is 0 is appropriately learned. It is preferable to use them.

  Furthermore, Patent Document 2 describes a technique for correcting a reaction force applied to a steering handle based on a signal from a yaw rate sensor.

JP 2000-81335 A JP 2008-221869 A

  According to the technique disclosed in Patent Document 2, the reaction force applied to the steering handle is corrected based on the detection value of the yaw rate sensor. When the difference between the yaw rate sensor temperature and the current yaw rate sensor temperature is large, the accuracy is reduced even if the yaw rate is corrected by the midpoint, and the reaction force applied to the steering handle based on it This correction may cause different values of reaction force control for the left and right yaw rate values, giving the driver a sense of incongruity.

  Therefore, the present invention gives the driver a sense of incongruity in the correction of the control performed according to the detected value of the vehicle behavior sensor when the change between the temperature at the midpoint learning of the vehicle behavior sensor and the current temperature is large. It is an object of the present invention to provide an electric power steering device that does not exist.

  In order to solve the above-mentioned problems, an invention according to claim 1 is directed to an electric motor that adds power to a steering system that gives a steering angle to steered wheels, a steering force detection means that detects a manual steering force that acts on the steering system, and a vehicle. A vehicle behavior sensor for detecting the behavior, and a control means for causing the electric motor to generate a steering assist force based on at least the output of the steering force detection means. The control means controls the steering reaction force component of the steering assist force. An electric power steering device that corrects control according to a detection value of a vehicle behavior sensor, and obtains a vehicle behavior sensor temperature detection means for detecting the temperature of the vehicle behavior sensor and a signal from the vehicle behavior sensor as a midpoint value A midpoint value storage means for storing and a midpoint learning for acquiring the temperature of the vehicle behavior sensor when acquiring a signal from the vehicle behavior sensor as a midpoint value and storing it as a temperature during midpoint learning Temperature control means, and the control means performs control according to the detected value of the vehicle behavior sensor in accordance with the difference between the temperature of the vehicle behavior sensor during midpoint learning and the current temperature of the vehicle behavior sensor. The correction amount at the time of correction is adjusted.

  Then, as described in claim 2, the correction of the control to be performed according to the detected value of the vehicle behavior sensor as the difference between the temperature of the vehicle behavior sensor during the midpoint learning and the current temperature of the vehicle behavior sensor increases. It is desirable to reduce the correction amount at this time.

According to the first aspect of the present invention, the control means performs control according to the detected value of the vehicle behavior sensor in accordance with the difference between the temperature of the vehicle behavior sensor during the midpoint learning and the current temperature of the vehicle behavior sensor. Adjust the amount of correction when correcting. Conventionally, when the detection value of the yaw rate sensor fluctuates with the temperature change of the yaw rate sensor (when the middle point of the yaw rate sensor is incorrect), using the corrected yaw rate that has been subjected to the incorrect yaw rate midpoint correction, For example, when the control reaction force correction control (yaw rate reaction force control) for the turning operation of the steering handle is performed, different values of reaction force control are performed on the left and right yaw rate values. There is a possibility of giving a sense of incongruity.
However, by adjusting the correction amount in the correction control of the operation reaction force with respect to the turning operation of the steering handle as in the present invention, the temperature of the vehicle behavior sensor during the midpoint learning and the current temperature of the vehicle behavior sensor When the accuracy of the midpoint corrected yaw rate is low, the amount of reaction force control for different values for the left and right yaw rate values is reduced by limiting the correction amount to a small value. Do not give the driver a sense of incongruity.

  According to the present invention, in the control correction performed according to the detection value of the vehicle behavior sensor, the driver feels uncomfortable even when the change between the temperature at the midpoint learning of the vehicle behavior sensor and the current temperature is large. It is possible to provide an electric power steering device that is not given.

It is a figure which shows the principal part inside a vehicle containing VSA_ECU. It is a functional block block diagram of VSA_ECU. It is a functional block block diagram of EPS_ECU. It is explanatory drawing of a yaw rate reaction force correction | amendment limiting coefficient.

Hereinafter, an electric power steering apparatus according to an embodiment of the present invention will be described with reference to the drawings as appropriate.
First, with reference to FIG. 1 and with reference to FIG. 2 as appropriate, main parts inside the vehicle 1 including the EPS_ECU 20 and the VSA_ECU 30 will be described.

  As shown in FIG. 1, the vehicle 1 includes a steering mechanism, an electric power steering device 5, an engine control ECU 13 that controls an engine (not shown), an EPS_ECU 20 that is a control function unit of the electric power steering device 5, and braking control. A VSA_ECU 30 that controls vehicle behavior by combining an ABS function and a TCS function is provided.

(Vehicle steering mechanism)
First, a steering mechanism (steering system) including the electric power steering device 5 of the vehicle 1 will be described with reference to FIG.
The steering mechanism of the vehicle 1 is a pinion that rotates integrally with a pinion gear (not shown) that meshes with a rack tooth (not shown) of a rack shaft (not shown) of a rack and pinion mechanism (not shown). A steering shaft 12 is connected to the shaft 11 via a universal joint, and a steering handle 21 is attached to the steering shaft 12.
Then, when the driver operates to rotate the steering handle 21, to move the rack shaft in the lateral direction to rotate the pinion gear, the front wheels 2 _FL is a steered wheel that is coupled to the rack shaft, 2 _FR translocations Rudder.

The electric power steering device 5 includes an electric motor 23 that generates a steering assist force (auxiliary steering torque) that reduces the steering force when the driver rotates the steering handle 21 and applies the steering assist force to the steering mechanism. .
The gear directly connected to the output shaft of the electric motor 23 meshes with the worm wheel gear provided on the pinion shaft 11, and when the driver rotates the steering handle 21, the pinion is rotated by the rotation of the output shaft of the electric motor 23. An auxiliary steering torque for the shaft 11 is generated to reduce the steering force.

The EPS_ECU 20, which is a control unit of the electric power steering apparatus 5, includes a CPU (Central Processing Unit) 20a (see FIG. 3), a ROM (Read Only Memory) 20c (see FIG. 3), and a RAM (Random Access Memory) 20d (see FIG. 3). 3), a writable nonvolatile memory 20f (see FIG. 3), an input / output interface (not shown), a bus 20b for connecting them, an input / output interface circuit, and a peripheral circuit (in FIG. For example, the CPU executes a program stored in the ROM 20c to drive and control the motor 23 via the motor drive circuit 22.
Incidentally, the electric motor drive circuit 22 is a power supply circuit including a switching element for supplying electric power to the electric motor 23 that is a brushless motor.
The electric motor 23 is provided with a rotation angle sensor 25 that detects the rotation angle of the electric motor 23, and the signal is input to the EPS_ECU 20. For example, a resolver is used as the rotation angle sensor 25.

A torque sensor (steering force detection means) S _Trq is attached to the pinion shaft 11 described above, detects a steering torque when the driver rotates the steering handle 21, and a torque signal is input to the EPS_ECU 20. The
Then, as will be described later, the EPS_ECU 20 acquires information such as the steering angle δ, the corrected yaw rate γ ^* , the lateral acceleration α _X , and the vehicle speed VS from the VSA_ECU 30 via a CAN (Controller Area Network) communication line 50. Further, the information on the rotation angle and steering torque of the motor 23 is also used to control the motor 23 according to the behavior of the vehicle, such as the running state of the vehicle (turning, straight traveling) and the vehicle speed, thereby generating a steering assist force and the driver. The steering force of the steering handle 21 is controlled and a reaction force with respect to the turning operation direction of the steering handle 21 is applied.
In the control for applying the reaction force, the EPS_ECU 20 uses the actual yaw rate (the yaw rate γ ^* corrected by correcting the yaw rate midpoint described later).
Details of the control of the steering assist force and the steering reaction force in the EPS_ECU 20 will be described later.

(Engine control ECU)
The engine control ECU 13 includes a microcomputer (not shown) including a CPU, a ROM, a RAM, an input / output interface, a peripheral circuit, an FI drive circuit for driving a fuel injector, and the like. Various sensor signals such as sensors required for engine control are input. Intake air temperature is therein (hereinafter, referred to as "outside air temperature") includes an intake air temperature sensor S _Tair to detect (see FIG. 1). Then, the CPU executes a program stored in the ROM to control the output of the engine, and information necessary for the VSA_ECU 30 such as the engine rotation speed and the outside air temperature T _Air (see FIG. 2) is described later. Or output.

(VSA_ECU)
Next, the VSA_ECU 30 will be described with reference to FIG.
As shown in FIG. 2, the VSA_ECU 30 includes a microcomputer including a CPU 30a, a ROM 30c, a RAM 30d, a rewritable nonvolatile memory (midpoint value storage means) 30f, an input / output interface (not shown), a bus 30b for connecting them, and the like. The CPU 30a executes peripheral programs (in FIG. 2, “input / output interface circuit 30g”) and the like, and executes a program stored in the ROM to control the vehicle behavior. The VSA_ECU 30 is disposed in the engine room 3, for example.

The VSA_ECU 30 includes a signal from a steering angle sensor S _HA that detects a steering angle δ (see FIG. 2) of the front wheels 2 _FL and 2 _{FR that} are steered wheels, and each wheel 2 _FL , 2 _FR , 2 _{RL of the} vehicle 1. , the wheel speed sensors S _VWFL for detecting a wheel speed of 2 _RR, S _VWFR, S _VWRL, signals indicating the wheel speeds V _W (see FIG. 2) from S _VWRR, a yaw rate sensor disposed in the engine room 3 ( is a detection value from a vehicle behavior sensor) S _Y yaw rate gamma (signal indicating the reference 2), a yaw rate sensor S temperature sensor (vehicle behavior sensor temperature detection means for detecting the temperature of _Y) yaw rate sensor temperature from S _TY T _Y A signal indicating (see FIG. 2), a signal indicating the lateral acceleration α _X (see FIG. 2) from the lateral acceleration sensor Sα _X for detecting the lateral acceleration of the vehicle 1 and the like are input.

Here, the yaw rate sensor temperature T _Y corresponds to "a temperature of the vehicle behavior sensor" described in the appended claims.
Hereinafter, the wheel _{2 FL, 2 FR, 2 RL} , 2 RR, wheel speed sensors _{S VWFL, S VWFR, S VWRL} , S VWRR and below which brake device _{B FL, B FR, B RL} , B RR is necessary to distinguish Unless otherwise, they are simply referred to as “wheel 2”, “wheel speed sensor S _VW ”, and “brake device B”.
Incidentally, the wheel speed sensor S _VW is a sensor that detects the rotational speed of the wheel 2 as the number of pulses per unit time.
Also, as a typical peripheral circuit, the input / output interface circuit 30g typically includes a sensor signal signal processing circuit such as a filter circuit and a CAN communication signal processing unit.

Note that the yaw rate sensor S _Y and the temperature sensor S _TY are incorporated in the VSA_ECU 30, for example. The yaw rate sensor S _Y uses, for example, a semiconductor element, and the detected value may vary with the temperature change of the yaw rate sensor S _Y.

The VSA_ECU 30 hydraulically controls each brake device B (shown as “B _FL , B _FR , B _RL , B _RR ” in FIG. 1) provided on each wheel 2 _FL , 2 _FR , 2 _RL , 2 _RR individually. Is connected to a hydraulic circuit control unit 31a that drives a control valve (not shown) included in the hydraulic circuit 31 for brake control and outputs a control signal to the hydraulic circuit control unit 31a. The brake device B _FL , B _FR , B _RL , B _RR is controlled via the hydraulic circuit control unit 31 a by receiving a hydraulic signal from the control unit 31 a.
The VSA_ECU 30 is connected to the EPS_ECU 20 via the CAN communication line 50 and configured to be able to exchange data with each other. The VSA_ECU 30 outputs information such as the steering angle δ, the corrected yaw rate γ ^* , the lateral acceleration α _X , the vehicle speed VS, and the like to the EPS_ECU 20 via the CAN communication line 50, and via the CAN communication line 50 as necessary. Output control instruction information to the engine control ECU 13. Conversely, VSA_ECU30 acquires information of the steering torque T _rq from EPS_ECU20 via the CAN communication line 50.

Next, with reference to FIG. 2, the midpoint learning of learning the midpoint value of the signal from the yaw rate sensor S _{Y in the} VSA_ECU 30, that is, the detection value from the yaw rate sensor S _Y when the yaw rate γ of the vehicle 1 is zero. A method will be described.
The CPU 30a of the VSA_ECU 30 includes a vehicle speed calculation unit 41, a midpoint learning condition establishment determination unit 42, a midpoint determination unit 43, and a learning midpoint storage unit as functional components realized by executing a program stored in the ROM 30c. (Midpoint value storage means, midpoint learning temperature storage means) 44, a yaw rate correction unit 45, and a VSA control unit 46 are included.

The vehicle speed calculation unit 41 reads a signal indicating the wheel speed V _W from each wheel speed sensor S _VW , calculates the vehicle speed VS of the vehicle 1, and outputs it to the midpoint learning condition establishment determination unit 42 and the VSA control unit 46.
Midpoint learning condition establishment determining unit 42 has a pre-stored midpoint learning condition data 42a in ROM 30c, the current vehicle speed VS, steering angle [delta], on the basis of the yaw rate γ is the steering torque T _rq and the detected value, It is determined whether or not the midpoint learning condition of the yaw rate sensor S _Y is satisfied, and if it is satisfied, a midpoint learning permission signal is output to the midpoint determination unit 43. Otherwise, a midpoint learning permission signal is not output to the midpoint determination unit 43.

As for the midpoint learning condition, when any one of the following conditions A and B is satisfied, the midpoint learning condition establishment determining unit 42 determines that the midpoint learning condition is established.
<< Condition A >>
When the vehicle 1 has stopped for a predetermined time ΔTst and a predetermined time ΔTyaw shorter than the predetermined time ΔTst has elapsed since the vehicle 1 stopped.
<< Condition B >>
1. The fluctuation range of the yaw rate γ is within a predetermined value ΔYAW1.
2. Steering torque T _rq is within a predetermined value TRQ1.
3. The fluctuation range of the steering angle δ is within a predetermined value Δθ1.
4). The vehicle speed VS is equal to or higher than a predetermined value VEL1.
5.1. ~ 4. The state continues for time ΔT1.

The predetermined times ΔTst and ΔTyaw when the vehicle 1 of the condition A is stopped and the predetermined values of the condition B (ΔYAW1, TRQ1, Δθ1, VEL1, ΔT1) are the performance required for the vehicle 1, the steering angle sensor it may be set as appropriate based on such a sensitivity S _HA and the yaw rate sensor S _Y.

Midpoint determination unit 43, when receiving the signal of the midpoint learning permission from the midpoint learning condition establishment determining unit 42 compares the outside air temperature T _Air and yaw rate sensor temperature T _Y, outside air temperature T _Air and yaw rate sensor temperature If the difference in T _Y is smaller than the threshold value ε _TY , the current yaw rate γ that is the detected value is output to the learning midpoint storage unit 44 as the yaw rate midpoint value γ ₀ . Further, the yaw rate sensor temperature T _Y at that time is output to the learning midpoint storage unit 44 as the midpoint learning temperature T _Y ^* .
The learning midpoint storage unit 44 stores the yaw rate midpoint value γ ₀ output from the midpoint determination unit 43 in the midpoint data unit 44a of the non-volatile memory 30f and also stores the midpoint learning temperature T _Y ^* in the non-volatile memory 30f. Is stored in the midpoint learning temperature data section 44b. The yaw rate correction unit 45 outputs the yaw rate γ ^* corrected by performing the midpoint correction to the current yaw rate γ that is the detected value to the VSA control unit 46. In addition, the yaw rate correction unit 45 outputs the midpoint corrected yaw rate γ ^* , the midpoint learning temperature T _Y ^* , and the current yaw rate sensor temperature T _Y to the EPS_ECU 20 via CAN communication.

The VSA control unit 46 controls the brake device B of each wheel 2 via the hydraulic circuit 31 based on the vehicle speed VS, the midpoint corrected yaw rate γ ^* , the steering angle δ, and the lateral acceleration α _X , 1 or when the driver operates the brake pedal P _B (see FIG. 1), the braking control is performed via the hydraulic circuit 31, and the wheel speed V _W of each wheel 2 is monitored at that time. ABS control is performed to prevent the wheel 2 from being locked.

(Control of steering assist force and steering reaction force in EPS_ECU)
Next, details of the control of the steering assist force and the steering reaction force in the EPS_ECU 20 will be described with reference to FIGS. 3 and 4.
The EPS_ECU 20 includes a basic control unit 51, a steering reaction force control unit 52, a subtractor 53, and a drive current control unit 54. Finally, the target corresponding to the steering assist force generated by the motor 23 in the subtractor 53. A current It is calculated.

  The basic control unit 51 calculates a base current Ib that is a source of the target current It corresponding to the steering assist force generated by the electric motor 23 according to the manual steering force input to the steering handle 21 (see FIG. 1). At the same time, the assist current Ia is obtained by performing a necessary correction on the base current Ib. The basic control unit 51 includes a base current calculation unit 61, an inertia compensation unit 62 that compensates the inertia of the turning system, and a damper compensation unit 63 that compensates the damping of the turning system.

The base current calculation unit 61 obtains the base current Ib based on the steering torque T _rq by the torque sensor S _Trq and the vehicle speed VS acquired from the VSA_ECU 30 via CAN communication. The inertia compensating section 62, a time differential value of the steering torque T _rq by the steering torque sensor S _Trq, and calculates the inertia correction value based on the vehicle speed VS, corrects the base current Ib. The damper compensator 63 calculates a damping correction value based on the motor angular velocity ω obtained by time differentiation of the rotation angle θ by the rotation angle sensor 25 by the motor speed calculator 64 and the vehicle speed VS, and the base current Ib is corrected.

The steering reaction force control unit 52 includes a yaw rate reaction force correction current calculation unit 65 and a yaw rate reaction force limiting unit 66. The yaw rate reaction force correction current calculation unit 65 basically corresponds to the reaction force component of the steering assist force generated by the electric motor 23 according to the midpoint corrected yaw rate γ ^* acquired from the VSA_ECU 30 via CAN communication. The yaw rate reaction force correction current Iy is calculated.
Here, the yaw rate reaction force correction current calculation unit 65 calculates the yaw rate reaction force correction current Iy corresponding to the reaction force component of the steering assist force generated in the electric motor 23 according to the midpoint corrected yaw rate γ ^*. Corresponds to “correcting the control in accordance with the detection value of the vehicle behavior sensor” described in the claims.

The yaw rate reaction force limiting unit 66 has function data or a map set in advance for the difference between the yaw rate sensor temperature T _Y ^* during the midpoint learning and the current yaw rate sensor temperature T _Y. Incidentally, the function data or map data 66a is stored in a part of the storage area of the ROM 20c.
As shown in FIG. 4, in the function data or map data 66a, the horizontal axis is the difference between the yaw rate sensor temperature T _Y ^* during the midpoint learning and the current yaw rate sensor temperature T _Y (in FIG. 4, | current temperature T _Y -The learning temperature T _Y ^* | is indicated), and the vertical axis indicates the yaw rate reaction force correction limiting coefficient C multiplied by the yaw rate reaction force correction current Iy.
This yaw rate reaction force correction limiting coefficient C is 1.0 when | current temperature T _Y -learning temperature T _Y ^* | is 0, and as | current temperature T _Y -learning temperature T _Y ^* | increases. yaw rate reaction force correction limit coefficient C is decreased, the predetermined | current temperature T _Y - learning at the temperature T _Y ^* | in value, are set to saturate.

Then, the yaw rate reaction force limiting unit 66 calculates the difference between the yaw rate sensor temperature T _Y ^* during the midpoint learning acquired from the VSA_ECU 30 via CAN communication and the current yaw rate sensor temperature T _Y, and refers to the difference. The yaw rate reaction force correction limiting coefficient C is determined based on the function data or map data 66a. Further, the yaw rate reaction force limiting unit 66 multiplies the yaw rate reaction force correction current Iy by the determined yaw rate reaction force correction limit coefficient C and outputs the corrected yaw rate reaction force correction current Iy ^* to the subtractor 53.
Here, the yaw rate reaction force limiting unit 66 calculates the difference between the yaw rate sensor temperature T _Y ^* during the midpoint learning and the current yaw rate sensor temperature T _Y, and refers to the difference to obtain the above-described function data or map data. The yaw rate reaction force correction limiting coefficient C obtained based on 66a is multiplied by the yaw rate reaction force correction current Iy, according to the claims, “the temperature of the vehicle behavior sensor at the time of midpoint learning, the current This corresponds to “adjusting the correction amount in the correction of the control performed according to the detection value of the vehicle behavior sensor according to the difference with the temperature of the vehicle behavior sensor”.

In the basic control unit 51, the assist current Ia is set to increase as the manual steering torque increases. In the steering reaction force control unit 52, the yaw rate reaction force correction current Iy is changed to the actual yaw rate (corrected). As the absolute value of ⁽ yaw rate) γ ^* increases, the absolute value of yaw rate reaction force correction current Iy is also set to increase. As a result, even if the driver gives a large manual steering force to the steering handle 21, if the actual yaw rate γ ^* is large, the steering assist force of the motor 23 decreases and the steering reaction force applied to the driver increases. . In other words, the steering handle 21 becomes heavier, thereby preventing the driver from sensing the instability of the vehicle 1 and suppressing the driver's turning operation of the steering handle 21 to improve the running stability of the vehicle 1. At the same time, the operability of the driver can be improved.

In the subtractor 53, the yaw rate reaction force correction current Iy ^* is subtracted from the assist current Ia input from the basic control unit 51, and the target current It is input to the drive current control unit 54.

  In the drive current control unit 54, the U-phase, V-phase, and W-phase actual currents (indicated as “IU, IV, IW” in FIG. 3) supplied to the motor 23 from the motor drive circuit 22 and the target current It are calculated. The current supplied from the motor drive circuit 22 to the motor 23 is controlled so that the deviation becomes small. Specifically, the drive current control unit 54 controls the duty signal input to the switching element included in the motor drive circuit 22 so that the deviation becomes small.

According to the present embodiment, the yaw rate reaction force limiting unit 66 in the EPS_ECU 20 increases as the difference between the yaw rate sensor temperature T _Y ^* when the middle point learning of the yaw rate sensor S _Y is performed and the current yaw rate sensor temperature T _Y increases. The yaw rate reaction force correction current Iy calculated by the yaw rate reaction force correction current calculation unit 65 is reduced in accordance with the actual yaw rate γ ^* corrected based on the midpoint value γ ₀ learned at the yaw rate sensor temperature T _Y ^*. Restrict.
Thus, the yaw rate sensor S when the detected value of the yaw rate sensor S _Y in accordance with the temperature change of _Y is varied (if the midpoint of the yaw rate sensor S _Y is not correct), the corrected which received incorrect yaw rate midpoint correction using yaw rate gamma ^*, and the operation for turning operation of the steering wheel 21 reaction force correction control (yaw rate reaction force control), the left and right portions of the same yaw rate value, performs reaction force control of different values This can prevent the driver from feeling uncomfortable.

Further, in the present embodiment, in VSA_ECU30, not it is assumed that performs midpoint learning of the yaw rate sensor S _Y being limited thereto. The VSA_ECU 30 transmits the detected yaw rate γ to the EPS_ECU 20 via the CAN communication line 50, the midpoint learning is performed on the EPS_ECU 20 side as described above, and the midpoint corrected yaw rate γ ^* is converted to the CAN communication line. 50 may be transmitted to another ECU, for example, VSA_ECU 30, and used for VSA control. Further, the yaw rate γ, which is the detected value of the yaw rate sensor S _Y , is directly input to the EPS_ECU 20, the midpoint learning is performed by the EPS_ECU 20 side as described above, and the yaw rate γ ^* whose midpoint is corrected is transmitted via the CAN communication line 50. ECU, for example, VSA_ECU 30, may be used for VSA control.

"Temperature of the vehicle behavior sensor" in the claims, in the present embodiment, a yaw rate sensor temperature T _Y, at a temperature of the yaw rate sensor S _Y itself, may be the temperature of the environment in which the yaw rate sensor S _Y is placed.

Furthermore, as the steering reaction force control unit 52 of the CPU 20a of the EPS_ECU 20, the reaction force component of the steering assist force is controlled according to the yaw rate γ ^* . However, as described in JP-A-2006-256425, The reaction force component of the steering assist force may be controlled so as to control the reaction force component of the steering assist force in accordance with the steering angle δ.

1 Vehicle 3 Engine Room 5 Electric Power Steering Device 20 EPS_ECU
21 Steering handle 30 VSA_ECU
30f Non-volatile memory (midpoint value storage means, midpoint learning temperature storage means)
42 midpoint learning condition establishment determination unit 42a midpoint learning condition data 43 midpoint determination unit 44 midpoint learning storage unit (midpoint value storage means, midpoint learning temperature storage means)
44a Midpoint data section 45 Yaw rate correction section 46 VSA control section 50 CAN communication line 51 Basic control section 52 Steering reaction force control section 65 Yaw rate reaction force correction current calculation section 66 Yaw rate reaction force limit section 66a Function data or map data S _Y yaw rate Sensor (vehicle behavior sensor)
S _HA rudder angle sensor S _TY temperature sensor (vehicle behavior sensor temperature detection means)
S _Trq torque sensor (steering force detection means)
S _Tair intake air temperature sensor T _Y yaw rate sensor temperature (temperature of a vehicle behavior sensor)
T _Air outside temperature T _rq Steering torque γ _Yaw rate VS _Vehicle speed δ Steering angle

Claims (2)

An electric motor that adds power to a steering system that gives a steering angle to steered wheels, a steering force detection means that detects a manual steering force acting on the steering system, a vehicle behavior sensor that detects a vehicle behavior, and at least the steering force detection Control means for causing the electric motor to generate a steering assist force based on the output of the means, the control means according to the detected value of the vehicle behavior sensor in the control of the steering reaction force component of the steering assist force An electric power steering device for correcting control,
Vehicle behavior sensor temperature detecting means for detecting the temperature of the vehicle behavior sensor;
Midpoint value storage means for acquiring and storing a signal from the vehicle behavior sensor as a midpoint value;
Midpoint learning temperature storage means for acquiring the temperature of the vehicle behavior sensor when acquiring a signal from the vehicle behavior sensor as a midpoint value and storing it as the temperature at the time of midpoint learning; and
The control means is configured to correct the control according to the detected value of the vehicle behavior sensor according to the difference between the temperature of the vehicle behavior sensor at the time of the midpoint learning and the current temperature of the vehicle behavior sensor. An electric power steering apparatus characterized by adjusting a correction amount of the power.   The greater the difference between the temperature of the vehicle behavior sensor at the time of the midpoint learning and the current temperature of the vehicle behavior sensor, the smaller the correction amount in the control correction performed according to the detection value of the vehicle behavior sensor. The electric power steering apparatus according to claim 1.

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