JP2017035979A - Electric power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power steering device that comprises a function by which an assist quantity (an estimated steering force value) that a vehicle requires is estimated and then compared with actual steering force so that neutral fixation of a torque sensor can be detected by making use of vehicle data on a camera and the like mounted on the vehicle, which can be smoothly transferred to a manual steering control mode.SOLUTION: An electric power steering device has a function by which an electric current command value is calculated based on steering torque from a torque sensor, a motor is driven based on the electric current command value so as to assist-control a steering system of a vehicle and an automatic steering control mode and a manual steering control mode are alternately switched, which performs a fault diagnosis of the torque sensor by comparing an estimated steering force value estimated based on vehicle data with detected actual steering force, during automatic operation in the automatic steering control mode, and when diagnosing that the sensor is in fault is transferred to the manual steering control mode.SELECTED DRAWING: Figure 5

Description

  The present invention has a function of switching between an automatic steering control mode and a manual steering control mode in steering control of a vehicle, calculates a current command value based on the steering torque of a torque sensor, and applies assist force by a motor to a steering system of the vehicle. Compared to the estimated steering force based on vehicle information from existing cameras, etc., and the actual steering force, especially for torque sensor failures (including abnormalities) during automatic operation in the automatic steering control mode. The automatic steering control mode is gradually released from the automatic steering control mode so as to reduce the sense of incongruity to the manual steering control mode, and the driver is notified of the failure.

  An electric power steering device (EPS) that applies a steering assist force (assist force) to a steering mechanism of a vehicle by a rotational force of a motor is provided with a steering shaft by a transmission mechanism such as a gear or a belt via a speed reducer. Alternatively, a steering assist force is applied to the rack shaft. Such a conventional electric power steering apparatus performs feedback control of the motor current in order to accurately generate the torque of the steering assist force. In feedback control, the motor applied voltage is adjusted so that the difference between the steering assist command value (current command value) and the motor current detection value is small. The adjustment of the motor applied voltage is generally performed by PWM (pulse width). This is done by adjusting the duty of modulation) control.

  The general configuration of the electric power steering apparatus will be described with reference to FIG. 1. A column shaft (steering shaft, handle shaft) 2 of a handle (steering wheel) 1 is a reduction gear 3, universal joints 4 a and 4 b, and a pinion rack mechanism 5. The tie rods 6a and 6b are connected to the steering wheels 8L and 8R via the hub units 7a and 7b. Further, the column shaft 2 is provided with a steering angle sensor 14 for detecting the steering angle θr of the handle 1 and a torque sensor 10 for detecting the steering torque Th, and a motor 20 for assisting the steering force of the handle 1 is a reduction gear. 3 is connected to the column shaft 2 through 3. The control unit (ECU) 30 that controls the electric power steering device is supplied with electric power from the battery 13 and also receives an ignition key signal IG via the ignition key 11. The control unit 30 calculates a current command value for assist control based on the steering torque Th detected by the torque sensor 10 and the vehicle speed Vs detected by the vehicle speed sensor 12, and a voltage obtained by compensating the current command value. The current supplied to the motor 20 is controlled by the control command value Vref. The steering angle θr is detected from the rudder angle sensor 14 but can also be obtained from a rotation sensor connected to the motor 20.

  The control unit 30 is connected to a CAN (Controller Area Network) 40 that transmits and receives various types of vehicle information, and the vehicle speed Vs can also be received from the CAN 40. The control unit 30 can be connected to a non-CAN 41 that exchanges communications, analog / digital signals, radio waves, and the like other than the CAN 40.

  The control unit 30 is mainly composed of a CPU (including MPU and MCU), and general functions executed by programs in the CPU are as shown in FIG.

  The function and operation of the control unit 30 will be described with reference to FIG. 2. The steering torque Th detected by the torque sensor 10 and the vehicle speed Vs detected by the vehicle speed sensor 12 (or from the CAN) are expressed as a current command value Iref1. The current command value calculation unit 31 to be calculated is input. The current command value calculation unit 31 calculates a current command value Iref1, which is a control target value of the current supplied to the motor 20, using an assist map or the like based on the input steering torque Th and vehicle speed Vs. The current command value Iref1 is input to the current limiting unit 33 through the adding unit 32A, and the current command value Iref3 whose maximum current is limited by the overheat protection condition is input to the subtracting unit 32B, and the motor current value Im being fed back The deviation Iref4 (= Iref3-Im) is calculated, and the deviation Iref4 is input to the PI control unit 35 for improving the characteristics of the steering operation. The voltage control command value Vref whose characteristics are improved by the PI control unit 35 is input to the PWM control unit 36, and the motor 20 is PWM driven via an inverter 37 as a drive unit. The current value Im of the motor 20 is detected by the motor current detector 38 and fed back to the subtraction unit 32B.

  Further, a rotation sensor 21 such as a resolver is connected to the motor 20, and the actual steering angle θs is detected. The adder 32A is added with the compensation signal CM from the compensator 34, and the compensation of the system system is performed by adding the compensation signal CM so as to improve the convergence and inertia characteristics. The compensator 34 adds the self-aligning torque (SAT) 343 and the inertia 342 by the adder 344, further adds the convergence 341 to the addition result by the adder 345, and the addition result of the adder 345 is the compensation signal CM. It is said.

  In recent years, the meaning of the term “automobile” is what the vehicle is supposed to be, such as using a camera, laser radar, etc. mounted on the vehicle to automatically brake and stop safely, or to support automatic driving. I'm approaching. In automatic driving assistance, usually, when a driver inputs torque with a steering wheel or other device, the electric power steering device detects steering torque with a torque sensor, and the information is used for control in the vehicle or the electric power steering device. It can be considered that the automatic driving support is canceled and the normal assist control (manual steering control) is returned to when switching is used.

  Here, even if the torque sensor becomes neutral (normal sensor voltage range) due to some failure or abnormality, the vehicle and the electric power steering device cannot detect the driver's manual input, and support automatic driving as it is. I will continue. This behavior is undesirable because the vehicle behavior is contrary to the driver's intention, and the feeling of discomfort increases.

Japanese Patent No. 3578488

  As shown in Japanese Patent No. 3578488 (Patent Document 1), a conventional torque sensor failure detection is performed in a steering system capable of manual steering control and automatic steering control. A sensor unit for detecting the steering angle, the turning angle on the tire side, and the operation of the steering control motor is provided. In addition to the signal pattern or steering torque signal from these sensor units, the motor unit, mechanical unit or sensor unit (torque sensor) (Including the failure).

  However, in the apparatus of Patent Document 1, it is necessary to provide a sensor in each part, and there is no mention of switching without a sense of incongruity from automatic steering control to manual steering control when a failure occurs. Accordingly, there is a demand for detecting the neutral fixation of the torque sensor during automatic operation and shifting to manual steering control without feeling uncomfortable when neutral fixation is detected. In addition, a countermeasure for a detection method when the torque sensor is neutrally fixed is required.

  The present invention has been made under the circumstances described above, and the object of the present invention is not to add a circuit or the like around a conventional torque sensor. It is possible to estimate the assist amount (steering force estimate value) that the vehicle will need, and to detect neutral sticking of the torque sensor compared to the actual steering force at that time. An object of the present invention is to provide an electric power steering apparatus that shifts to

  The present invention calculates a current command value based on a steering torque from a torque sensor, drives a motor with the current command value to assist and control a vehicle steering system, and includes an automatic steering control mode and a manual steering control mode. The above-mentioned object of the present invention relates to a steering force estimated value estimated based on vehicle information and detected actual steering during automatic driving in the automatic steering control mode. This is achieved by performing a failure diagnosis of the torque sensor by comparison with force and shifting to the manual steering control mode when the failure is diagnosed.

  The object of the present invention is that the actual steering force is an addition value of an input torque based on the steering torque and a motor output based on a motor current of the motor, or the addition value changes to a predetermined threshold or more. The automatic steering control mode by diagnosing the failure when the vehicle information is at least a camera, laser radar, GPS, ultrasonic wave, vehicle model, or when the failure is determined. By providing a switching control unit that performs gradual changeover to the manual steering control mode, or because the gradual change is a linear or non-linear characteristic, or when the failure is determined, By providing notifying means for notifying the driver, or the notifying means is at least one of visual information, sound, and vibration. By it, it is more effectively achieved.

  According to the electric power steering apparatus of the present invention, the motor is driven based on the steering torque from the torque sensor to assist the steering system of the vehicle, and the function of switching between the automatic steering control mode and the manual steering control mode is provided. In the electric power steering device, failure diagnosis (neutral fixation) of the torque sensor during automatic operation in the automatic steering control mode is performed. When the failure is diagnosed, the automatic steering control is canceled, and the manual steering control is gradually changed. As a result, the driver rarely feels uncomfortable. In addition, since the driver is notified of the failure, the driver does not have any doubt about the steering.

  Furthermore, failure diagnosis is performed by comparing the estimated steering force based on vehicle information such as the camera, laser radar, GPS, ultrasonic wave, and vehicle model mounted on the vehicle with the actual steering force. There is no need to add a circuit or the like.

It is a lineblock diagram showing an outline of an electric power steering device. It is a block diagram which shows the structural example of the control system of an electric power steering apparatus. It is a block diagram which shows an example of the electric power steering apparatus which has the switching function of automatic steering control mode and manual steering control mode. It is a flowchart which shows the schematic operation example of the electric power steering apparatus which has the switching function of automatic steering control mode and manual steering control mode. It is a block block diagram which shows an example of embodiment of this invention. It is a block diagram which shows the structural example of a failure determination part. It is a block diagram which shows an example of a comparison determination part. It is a time chart which shows the operation example of this invention. It is a part of flowchart which shows the operation example of this invention. It is a part of flowchart which shows the operation example of this invention. It is a time chart which shows the characteristic example (linear) of the gradual change switching from automatic steering control to manual steering control. It is a time chart which shows the characteristic example (nonlinear) of the gradual change switching from automatic steering control to manual steering control.

  According to the electric power steering device of the present invention, the vehicle control has a function of an automatic steering control mode and a manual steering control mode, has a switching function for switching between both modes, and a circuit added around a conventional torque sensor, etc. In addition, a torque sensor failure (including an abnormality) during automatic operation in the automatic steering control mode is detected with an estimated steering force estimated by vehicle information such as an existing camera, laser radar, ultrasonic wave, GPS, and vehicle model. Detecting based on comparison with steering force (input torque + motor output), canceling the automatic steering control mode gradually so as to reduce discomfort, shifting to manual steering control mode, and notifying the driver of the failure I have to. For this reason, it is possible to smoothly shift to manual steering control without making the driver feel uncomfortable with an inexpensive configuration, and the driver can also recognize the failure at an early stage.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

  First, referring to FIG. 3, an electric power steering apparatus which is a premise of the present invention, that is, a general electric power steering apparatus having functions of an automatic steering control mode and a manual steering control mode and having a function of switching the steering control mode will be described. I will explain.

  A rotation sensor 151 such as a resolver for detecting a motor rotation angle θs is connected to the motor 150, and the motor 150 is driven and controlled via a vehicle ECU 130 and an EPS (electric power steering device) ECU 140. The vehicle-side ECU 130 outputs a switching command unit 131 that outputs a switching command SW for automatic steering control or manual steering control based on buttons, switches, and the like indicating the driver's intention, and signals such as a camera (image) and a laser radar. And a target steering angle generator 132 for generating a target steering angle θt based on the target steering angle θt. The actual steering angle θr detected by the steering angle sensor 14 provided on the column shaft (steering shaft, steering wheel shaft) is input to the steering angle control unit 200 in the EPS side ECU 140 via the ECU 130.

  The switching command unit 131 is based on a signal for identifying that the vehicle enters the automatic steering control, for example, a signal indicating a vehicle state by a button or a switch provided on the dashboard or around the steering wheel or a parking mode provided for a shift. The switching command SW is output to the switching unit 142 in the EPS side ECU 140. The target steering angle generation unit 132 generates a target steering angle θt by a known method based on data such as a camera (image) and a laser radar, and the generated target steering angle θt is a steering angle in the EPS-side ECU 140. Input to the control unit 200.

  The EPS-side ECU 140 outputs a motor current command value Itref calculated based on the steering torque Th and the vehicle speed Vs, and based on the target steering angle θt, the actual steering angle θr, the motor angular speed ω, and the steering torque Th. A steering angle control unit 200 that calculates and outputs a motor current command value Imref for steering angle automatic control, a switching unit 142 that switches between motor current command values Itref and Imref by a switching command SW, and a motor from the switching unit 142 A current control / drive unit 143 that drives and controls the motor 150 based on the current command value Iref (= Itref or Imref), and a motor angular speed calculation unit 144 that calculates the motor angular velocity ω based on the motor rotation angle θs from the rotation sensor 151. It is equipped with. Based on the switching command SW from the switching command unit 131 of the vehicle side ECU 130, the switching unit 142 and the torque control mode (manual steering control) by the torque control unit 141 and the position / speed control mode (automatic by the steering angle control unit 200). Steering control) is switched, motor current command value Itref is output in manual steering control, and motor current command value Imref is output in automatic steering control. The current control / driving unit 143 includes a PI current control unit, a PWM control unit, an inverter, and the like.

  In such a configuration, an example of the schematic operation will be described with reference to the flowchart of FIG.

  When the operation of the steering system starts, torque control (manual steering control mode) is first performed by the torque control unit 141 (step S1), and the motor 150 is driven by the current control / drive unit 143 using the motor current command value Itref. (Step S2). The manual steering operation is repeated until the switching command unit 131 outputs a switching command SW to automatic steering control (step S3).

  When the automatic steering control mode is entered and a switching command SW is output from the switching command unit 131, the target steering angle θt is input from the target steering angle generation unit 132 (step S4), and the actual steering angle θr is input from the steering angle sensor 14. (Step S5), the steering torque Th is input from the torque sensor 154 (step S6), the motor angular speed ω is input from the motor angular speed calculation unit 144 (step S7), and the motor current command value Imref is calculated by the steering angle control unit 200. It is generated (step S10). Note that the input order of the target steering angle θt, the actual steering angle θr, the steering torque Th, and the motor angular velocity ω can be changed as appropriate.

  Thereafter, the switching unit 142 is switched by a switching command SW from the switching command unit 131 (step S11), and the motor 150 is driven by the current control / drive unit 143 using the motor current command value Imref from the steering angle control unit 200. (Step S12), the process returns to Step S3. The drive control (automatic steering control) based on the motor current command value Imref is repeated until the switching command SW is changed from the switching command unit 131.

  The present invention performs a failure diagnosis (including an abnormality) of the torque sensor 154 during the above-described automatic steering control mode without adding a new detection circuit around the torque sensor 154, and the failure of the torque sensor 154 (a normal sensor). When the neutral fixation (voltage range neutral fixation) is detected, the automatic steering control is gradually released so that there is less discomfort, and the driver smoothly shifts to manual steering control. The failure is notified by vibration or the like.

  FIG. 5 shows an embodiment of the present invention corresponding to FIG. 3, and the same members are denoted by the same reference numerals and description thereof is omitted.

  In the present invention, a failure determination unit 160 that detects a failure (neutral fixation) of the torque sensor 154 during automatic operation in the automatic steering control mode and outputs a failure signal FD, and outputs a steering switching signal SWC based on the failure signal FD. Then, the switching control unit 170 for controlling the switching unit 142 to be gradually switched from the automatic steering control to the manual steering control (gradual change switching), and the failure signal FD informs the driver of the failure of the torque sensor 154 by visual information, sound, vibration. And a notifying means 180 for notifying by the above.

  The details of the failure determination unit 160 have the configuration shown in FIG. 6. The failure determination unit 160 inputs a steering torque Th [N] as an operation force, and inputs the driver input torque Tci [Nm] based on the steering wheel radius [m]. ], A motor output calculation unit 162 that calculates a motor output Tmc based on the motor current Im (actual current), and a steering force is estimated based on vehicle information such as a camera and a laser radar. The steering force estimation unit 163, the addition unit 164 that adds the input torque Tci and the motor output Tmc, and the steering force TQ1 that is the addition result and the steering force estimation value STe from the steering force estimation unit 163 are input for comparison and determination. The comparison determination unit 166 that outputs the determination signal DC and the output unit 167 that outputs the determination signal DC from the comparison determination unit 166 according to the switching signal SW. A predetermined threshold THr is input to the comparison determination unit 166.

The comparison determination unit 166 is configured as shown in FIG. 7, the comparison unit 166-1 outputs the comparison result (difference) DR compares the steering force TQ1 and steering steering force estimate STe, comparison result DR Is compared with a predetermined threshold THr, and when the comparison result DR is less than the threshold THr (TQ1≈STe), for example, a determination signal DC indicating logic “0” indicating normality is output, and the comparison result DR is equal to or higher than the threshold THr. (TQ1 ≠ STe), the determination unit 166-2 outputs a determination signal DC of logic “1” indicating a failure.

The vehicle steering force estimation unit 163 inputs vehicle information such as a camera, a laser radar, an ultrasonic wave, a high-accuracy GPS, a vehicle model, a vehicle speed sensor, etc. mounted on the vehicle to maintain the lane of the vehicle that will be required in the future A necessary steering force STe is estimated. That is, the steering force estimation value STe from the steering force estimation unit 163 is a steering force necessary for the vehicle to maintain the lane, and the steering force TQ1 from the addition unit 164 is the steering force (motor) output from the EPS. Output Tmc) + hand input torque Tci,
(Equation 1)
STe ≒ TQ1

However, in the case of failure, the input torque Tci = 0 is calculated, so that the comparison in the comparison estimation unit 166 is
(Equation 2)
STe vs. Tmc + Tci (= 0)

It becomes. If the handle is released, the steering torque Th = 0.
(Equation 3)
STe = Tmc

It will not be a failure judgment. However, when neutral fixation occurs in the torque sensor 154, the motor output Tmc increases or decreases by the steering torque Th,
(Equation 4)
STe ≠ Tmc

Therefore, a failure (neutral fixation) can be detected.

  Details of the neutral sticking detection will be described below.

Under normal conditions, the manual input from the steering wheel (steering torque Th) is expressed by the following formula 5, and the motor current Im is expressed by the following formula 6.
(Equation 5)
Manual input [Nm] = handle radius [m] × operating force [N] = driver input torque [Nm] = steering torque Th detected by torque sensor 154

(Equation 6)
Motor current Im = Iref [A] = Assist map (manual input of equation 5 vs motor current Im)

Further, when the motor torque constant of the motor 150 is Kt, the gear ratio of the worm and the worm wheel is Gn, the gear efficiency of the worm wheel is Gζ, and the gear efficiency of the rack and pinion is Gξ, the motor output which is the actuator output [Nm] Tmc [Nm] is expressed by the following formula 7.
(Equation 7)
Motor output Tmc [Nm] = Kt × Im × Gn × Gζ = Assist force [Nm]

The steering force TQ1 [Nm] in the column type electric power steering is expressed by the following formula 8, and the steering force TQ1 [Nm] in the rack type electric power steering is expressed by the following formula 9.
(Equation 8)
Steering force TQ1 [Nm] = Driver input torque Tci + Motor output Tmc
(Equation 9)
Steering force TQ1 [N] = (motor output Tmc + driver input torque Tci) 2π × Gξ / rack and pinion ratio [mm]

Further, the steering force estimated value STe is expressed by the following formula 10.
(Equation 10)
Steering force estimated value STe [Nm] = estimated value

In the above formula 10, since the estimated value is a force necessary for maintaining the lane calculated from the camera or the like, the input torque of the driver is not related.

Here, at normal time, Equation 8≈Equation 10 or Equation 9≈Equation 10. That is, the following formula 11 or formula 12 holds.
(Equation 11)
Steering force TQ1 [Nm] = Driver input torque Tci + Motor output Tmc≈Steering force estimated value STe [Nm]
(Equation 12)
Steering force TQ1 [N] = (motor output Tmc + driver input torque Tci) 2π × Gξ / rack and pinion ratio [mm] ≈steering force estimated value STe [Nm]

When the torque sensor 154 is neutral and fixed during automatic driving and the driver inputs a handle, the relationship of the above formula 11 or 12 changes as the following formula 13.
(Equation 13)
Driver's actual input torque Tci (increase ↑) + motor output Tmc (decrease ↓)

Equation 13 is obtained, but since the detection input torque Tci is 0 due to neutral fixation, Equation 11 is expressed by (Equation 14).
Driver input torque Tci (0) + motor output Tmc (decrease) <steering force estimation value STe (no change)

Thus, the failure can be detected. In the present embodiment, the failure signal FD is output when the motor output Tmc (decrease) fluctuates and becomes smaller than the threshold THr.

  FIG. 8 shows an example of the operation of the present invention. As shown in FIG. 8B, when the torque sensor 154 fails at time t1, the detected torque Tci becomes “0”. In addition, the estimated output value (= Tmc + Tci) of the motor 150 varies. Therefore, a failure of the torque sensor 154 can be detected by comparing the steering force estimated value STe with the actual steering force (= Tmc + Tci). That is, when the deviation between the steering force estimated value STe and the actual steering force (= Tmc + Tci) is equal to or greater than a predetermined value (threshold THr), it is detected as a torque sensor failure.

  Next, an example of the operation of the present invention will be described with reference to the flowcharts of FIGS. Note that the operations not relevant to the present invention are described in the flowchart of FIG.

  Since the present invention is detection of neutral fixation of the torque sensor 154 and switching of the steering control mode in the automatic steering control mode, the failure determination unit 160 and the switching control unit 170 are in the automatic steering control mode by the switching command SW. (Step S20).

  In the automatic steering control mode, first, the input torque calculator 161 calculates the input torque Tci from the steering torque Th and the handle radius (step S21), and the motor output calculator 162 calculates the motor output Tmc based on the motor current Im. (Step S22), the steering force estimation unit 163 estimates a steering force estimation value STe based on vehicle information such as a camera, laser radar, and GPS (step S23). The order of calculation of the input torque Tci, calculation of the motor output Tmc, and estimation of the steering force estimated value STe can be changed as appropriate.

  Thereafter, the input torque Tci and the motor output Tmc are added by the adding unit 164 (step S24), and the steering force TQ1 and the steering force estimated value STe from the steering force estimating unit 163, which are the addition results of the adding unit 164, are compared and determined. Is input to the comparison unit 166-1 and compared (step S25), the comparison result DR of the steering force TQ1 and the estimated steering force STe is input to the determination unit 166-2, and the comparison result DR is compared with the threshold THr. (Step S26). If the comparison result DR is less than the threshold THr, it is normal and the process returns to step S21 to repeat the above operation.

  In step S26, if the comparison result DR is greater than or equal to the threshold THr, a failure is detected, and a failure detection determination signal DC is output (step S30). The determination signal DC is input to the output unit 167. In this case, since the switching signal SW is in the automatic steering control mode, the failure signal FD is output from the output unit 167 (step S31). When the failure signal FD is output, the notification unit 180 notifies the driver of the failure with visual information, sound, vibration, etc. (step S32), and also outputs a steering switching signal SWC from the switching control unit 170 to switch the switching unit 142. Switch to manual steering control mode (step S33). This switching is performed by a gradual change process as shown in FIG. 11 (step S34). That is, the automatic steering control mode is 100% (manual steering control 0%) until time t10, and when the failure signal FD is output at time t10, manual steering control is gradually (linearly) performed from the automatic steering control. The manual steering control becomes 100% (automatic steering control 0%) at time t11 (step S35).

  The gradual change process may be a non-linear characteristic as shown by characteristics A and B in FIG. 12, and the order of notification and steering switching may be reversed.

  In addition, the determination signal DC of the determination unit 166-2 is set to logic “0” when normal, and is set to logic “1” when failure (abnormal), but may be reversed. Further, in the above-described embodiment, constants, efficiencies, and the like are expressed as coefficients for convenience, but functions or maps related to temperature, friction, speed, and the like may be used.

1 Handle (steering wheel)
2 Column shaft (steering shaft, handle shaft)
10, 154 Torque sensor 12 Vehicle speed sensor 13 Battery 14 Rudder angle sensor 20, 150 Motor 30 Control unit (ECU)
31 Current command value calculating unit 33 Current limiting unit 34 Compensating unit 35 PI control unit 36 PWM control unit 37 Inverter 130 Vehicle side ECU
140 EPS side ECU
160 failure determination unit 170 switching control unit 180 notifying means 200 rudder angle control unit

Claims (8)

A current command value is calculated based on the steering torque from the torque sensor, the motor is driven by the current command value to assist the steering system of the vehicle, and the automatic steering control mode and the manual steering control mode are switched to each other. In an electric power steering device having a function,
When the torque sensor is diagnosed for failure by comparing the estimated steering force estimated based on vehicle information with the detected actual steering force during automatic driving in the automatic steering control mode. And shifting to the manual steering control mode. The electric power steering apparatus according to claim 1, wherein the actual steering force is an added value of an input torque based on the steering torque and a motor output based on a motor current of the motor. The electric power steering apparatus according to claim 2, wherein the failure is diagnosed when the added value changes to a predetermined threshold or more. The electric power tearing device according to any one of claims 1 to 3, wherein the vehicle information is at least a camera, a laser radar, a GPS, an ultrasonic wave, and a vehicle model. The electric power tearing according to any one of claims 1 to 4, further comprising a switching control unit that gradually switches from the automatic steering control mode to the manual steering control mode when the failure is determined. apparatus. The electric power tearing device according to claim 5, wherein the gradual change is a linear or non-linear characteristic. The electric power steering apparatus according to any one of claims 1 to 6, further comprising notification means for notifying a driver when the failure is determined. The electric power steering apparatus according to claim 7, wherein the notification unit is at least one of visual information, sound, and vibration.

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