JP2005088709A - Steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steering device capable of accurately performing abnormality determination processing for a steering angle detected by a rudder angle sensor which is applicable to end abutting impact avoiding control. <P>SOLUTION: It is determined whether a steering wheel is in a neutral position or not based on a vehicle speed V, a steering speed ωre and steering torque Ts. When the state that the steering wheel is in the neutral position continues for a predetermined time period, an average value of a detected steering angle θ in the predetermined time period is calculated. When the average value is equal to or more than a predetermined angle, the steering angle detected by the rudder angle sensor 2 is determined to be abnormal. When the average value of the steering angle is less than the predetermined angle, the steering speed ωre at the predetermined time period is integrated. A difference between the integrated value of the steering speed ωre at the predetermined time period and the detected steering angle θ after the predetermined time period is calculated, and it is determined that the steering angle detected by the rudder angle sensor 2 is abnormal when the difference is equal to or more than the predetermined value. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a steering device, and more particularly to abnormality detection of a steering angle sensor that detects a steering angle of a steering wheel that is an operation means of the steering device.

  2. Description of the Related Art Conventionally, an electric power steering apparatus that applies a steering assist force to a steering mechanism by driving an electric motor in accordance with a steering torque applied to a steering wheel (steering wheel) by a driver has been used. This electric power steering apparatus is provided with a steering angle sensor that detects a steering angle of a steering wheel, which is an operation means for steering, and a steering angle detected by the steering angle sensor (hereinafter referred to as “detected steering angle”). Based on the above, damping control for improving handle convergence, handle return control for improving handle return performance, and the like are performed. In such an electric power steering apparatus, when the driver rotates the handle to the maximum steering angle, the rotation of the handle is forcibly stopped (hereinafter, the rotation of the handle is forcibly stopped). ("End contact") reduces the sound and impact generated during end contact (hereinafter referred to as "end contact impact avoidance control"). It has become.

The end contact impact avoidance control is effectively performed based on the steering angle and steering speed of the steering wheel. However, the adjustment of the neutral position of the rudder angle sensor that detects the steering angle is performed in a state where the rudder angle sensor is mounted on the vehicle, so that it is difficult to accurately adjust. For example, an error may occur in the detected steering angle due to the influence of an error such as a ball screw. If an error occurs in the detected steering angle, the position of the handle when the detected steering angle is zero does not match the position of the handle when the vehicle is actually running in a straight line. In view of the difficulty of adjusting the neutral position of the rudder angle sensor in this way, Japanese Patent No. 2970351 discloses a detection steering angle based on an average value over a certain period of time under the condition that the vehicle is traveling straight. An invention in which the detected steering angle is corrected is disclosed. In the invention disclosed in Japanese Patent Laid-Open No. 2002-2516, the neutral position of the steering wheel is estimated from the detected steering angle, the steering speed, and the steering torque. Then, the current command value for driving the motor is corrected according to the estimated neutral position. Incidentally, in the above-described damping control and steering wheel return control, even if an error occurs in the detected steering angle, the influence of the error is small. For this reason, the conventional determination process (hereinafter referred to as “steering angle abnormality determination process”) as to whether or not the detected steering angle is abnormal has been simple. Conventionally, for example, if the detected steering angle is larger than the maximum steering angle at which the steering wheel can rotate, it is determined that the detected steering angle is abnormal.
Japanese Patent No. 2970351 JP 2002-2516 A

  However, in the end contact impact avoidance control, if an error occurs in the detected steering angle, the effect of the error is large, and it is difficult to achieve the purpose of avoiding the sound and impact during end contact. For this reason, in the end contact impact avoidance control, a simple steering angle abnormality determination process that has been conventionally performed is insufficient. The inventions disclosed in Japanese Patent No. 2970351 and Japanese Patent Application Laid-Open No. 2002-2516 are for adjusting the deviation between the neutral position of the handle and the actual neutral position of the handle based on the detected steering angle. It is not determined with high accuracy whether or not an error occurs in the detected steering angle.

  Therefore, an object of the present invention is to provide a steering device that performs a steering angle abnormality determination process that can detect with high accuracy whether or not the steering angle of a steering wheel detected by a steering angle sensor is abnormal.

A first invention is a steering device for steering a vehicle in response to an operation by an operating means,
Torque detecting means for detecting steering torque applied to operating means for steering the vehicle;
Rudder angle detection means for detecting a steering angle which is an operation angle of the operation means;
Steering speed detection means for detecting the steering speed of the operation means independently of the steering angle detection means;
Rudder angle abnormality determining means for determining whether or not a detected steering angle that is a steering angle detected by the rudder angle detecting means is abnormal,
The rudder angle abnormality determining means is
Independently of the steering angle detection means, it is determined whether or not the operation means is in a neutral position, and based on the detected steering angle when it is determined that the operation means is in a neutral position, the detected steering angle First determination means for determining whether or not is abnormal,
And second determining means for determining whether or not the detected steering angle is abnormal based on the detected steering angle and a steering angle calculated from the steering speed.

According to a second invention, in the first invention,
Vehicle speed detecting means for detecting the vehicle speed of the vehicle,
The first determination means includes
Neutral position determining means for determining whether or not the operating means is in a neutral position based on the vehicle speed, the steering speed, and the steering torque;
When it is determined by the neutral position determining means that the operating means is in the neutral position continuously for a first predetermined time, an average value of the detected steering angles at the first predetermined time is equal to or greater than a first predetermined value. If so, a first abnormality detection means for determining that the detected steering angle is abnormal,
It is characterized by including.

According to a third invention, in the first invention and the second invention,
The second determination means includes
Integrating means for calculating an integral value of the steering speed;
A second abnormality detecting means for determining that the detected steering angle is abnormal if a difference between the detected steering angle and the integrated value at a second predetermined time is equal to or greater than a second predetermined value;
It is characterized by including.

  According to the first aspect, the first determination process and the second determination process determine whether or not the steering angle detected by the steering angle detection means is abnormal. In the first determination process, it is determined whether or not the detected steering angle is abnormal based on the steering angle detected when the operating means is in the neutral position. In the second determination process, whether or not the detected steering angle is abnormal is determined based on the steering angle calculated by the means independent of the steering angle detection means and the steering angle detected by the steering angle detection means. Is determined. Thereby, an abnormality in the detected steering angle when the operating means is in the neutral position and an abnormality in the detected steering angle when the operating means is rotated are detected. For this reason, an abnormality in the detected steering angle is detected with higher accuracy than in the past, and an abnormality that has not been detected in the past is also detected. And the reliability of the motor control based on the steering angle detected by the steering angle detection means can be improved.

  According to the second aspect, in the first determination process, it is determined whether or not the operating means is in the neutral position based on the vehicle speed, the steering speed, and the steering torque. For this reason, the conventional vehicle speed detection means, torque detection means, and steering speed detection means determine whether or not the midpoint of the detected steering angle is normal, and if it is normal, the second determination process is performed. As in the first invention, the abnormality of the steering angle detected by the steering angle detection means is detected with higher accuracy than in the prior art.

  According to the third invention, as in the first and second inventions, the steering angle abnormality detected by the steering angle detection means is detected with higher accuracy than in the prior art, and the abnormality that has not been detected in the past is also detected. Detected.

  Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

<1. Overall configuration>
FIG. 1 is a schematic diagram showing a configuration of an electric power steering apparatus according to an embodiment of the present invention, together with a vehicle configuration related thereto. This electric power steering apparatus includes a steering shaft 102 having one end fixed to a handle 100 as an operation means for steering, a rack and pinion mechanism 104 connected to the other end of the steering shaft 102, and a steering angle of the handle 100. A steering angle sensor 2 for detecting θ, a torque sensor 3 for detecting a steering torque Ts applied to the steering shaft 102 by an operation of the handle 100, a vehicle speed sensor 4 for detecting a traveling speed V of the vehicle, and a driving by a steering operation Brushless motor 6 that generates a steering assist force for reducing the load on the user, a ball screw drive unit 11 that transmits the steering assist force to the rack shaft, and a position detection sensor that detects the rotational position of the rotor of the brushless motor 6 12 and the steering angle sensor receiving power supply from the in-vehicle battery 8 , And an electronic control unit (ECU) 5 for controlling the driving of the motor 6 based on sensor signals from the torque sensor 3, the vehicle speed sensor 4 and the position detecting sensor 12.

  When the driver operates the steering wheel 100, based on the steering torque Ts detected by the torque sensor 3, the vehicle speed V detected by the vehicle speed sensor 4, and the rotational position (rotation angle θre) of the rotor detected by the position detection sensor 12. Thus, the motor 6 is driven by the ECU 5. As a result, the motor 6 generates a steering assist force, and the steering assist force is applied to the rack shaft via the ball screw drive unit 11, thereby reducing the driver's load. That is, the rack shaft reciprocates by the steering torque Ts applied by the steering operation and the steering assist force generated by the motor 6. Both ends of the rack shaft are connected to a wheel 108 via a connecting member 106 composed of a tie rod and a knuckle arm, and the direction of the wheel 108 changes according to the reciprocating motion of the rack shaft.

<2. Configuration of control device>
FIG. 2 is a block diagram showing a configuration of the ECU 5 which is a control device in the electric power steering apparatus. The ECU 5 includes a microcomputer (hereinafter abbreviated as “microcomputer”) 10 and a motor drive unit. The microcomputer 10 executes a predetermined program stored in its internal memory, whereby the target current setting unit 114, the steering angle abnormality determination unit 170, the subtractors 122 and 124, and the d-axis current PI control unit 126. A q-axis current PI control unit 128, a dq / 3-phase AC coordinate conversion unit 132, a sign inversion adder 134, a three-phase AC / dq coordinate conversion unit 138, a rotor angular velocity calculation unit 142, It functions as a motor control part comprised from. The motor drive unit is hardware (circuit) that drives the three-phase brushless motor 6 based on a voltage command value output from the microcomputer 10 serving as a motor control unit. The PWM signal generation circuit 150, the motor drive circuit 152, , U phase current detector 156, V phase current detector 154, and rotor angular position detector 162. Further, the ECU 5 is provided with a relay (not shown), and power is supplied to the motor drive unit and the brushless motor 6 while the relay is closed.

  When the steering wheel 100 is operated, the steering torque Ts detected by the torque sensor 3, the vehicle speed V detected by the vehicle speed sensor 4, and the steering angle (detected steering angle) θ detected by the steering angle sensor 2 are input to the ECU 5. Is done. In addition, based on the sensor signal output from the position detection sensor 12 attached to the motor 6, the rotor angle position detector 162 rotates the rotation field (permanent magnet) that is the rotor of the motor 6, ie, the electrical angle ( A signal indicating the rotor angle) θre is output. The rotor angular speed calculation unit 142 outputs a rotor angular speed (steering speed) ωre based on the rotor angle θre. The position detection sensor 12 is, for example, a resolver, and the position detection sensor 12, the rotor angular position detector 162, and the rotor angular speed calculation unit 142 implement a steering speed detection unit. By this steering speed detection means, the steering speed ωre is detected independently of the steering angle sensor 2.

The target current setting unit 114 outputs a q-axis current command value iq ^* based on the steering torque Ts, the vehicle speed V, the steering angle θ, and the rotor angular speed ωre. The q-axis current command value iq ^* is a current value corresponding to the torque that should be generated by the motor 6 and is input to the subtractor 124. On the other hand, the d-axis current command value id ^* is input to the subtractor 122 as id ^* = 0 because it does not relate to the torque. Here, the target current setting unit 114 stores a table referred to as an assist map that associates the steering torque with the target current value. The target current setting unit 114 corresponds to the steering angle θ detected by the steering angle sensor 2. The assist current is reduced in order to reduce the steering assist force so as to reduce the impact at the time of application. In addition, the steering angle abnormality determination unit 170 performs a steering angle abnormality determination process based on the steering torque Ts, the vehicle speed V, the steering angle θ, and the rotor angular speed ωre. Then, an abnormality determination result signal S indicating the determination result of the steering angle abnormality determination process is output from the steering angle abnormality determination unit 170 and input to the target current setting unit 114.

The three-phase AC / dq coordinate converter 138 converts the U-phase motor current value iu and the V-phase motor current value iv based on the electrical angle θre of the rotor into a d-axis motor current that is a value on the dq coordinate. The value id and the q-axis motor current value iq are converted. The d-axis motor current value id and the q-axis motor current value iq are input to the subtractor 122 and the subtractor 124, respectively. The subtractor 122 outputs a deviation id ^* -id between the d-axis current command value id ^* and the d-axis motor current value id. Then, the d-axis current PI control unit 126 outputs the d-axis voltage command value vd ^* by a proportional integration calculation based on the deviation id ^* -id. On the other hand, the subtractor 124 outputs a deviation iq ^* -iq between the q-axis current command value iq ^* and the q-axis motor current value iq. Then, the q-axis current PI control unit 128 outputs the q-axis voltage command value vq ^* by proportional-integral calculation based on the deviation iq ^* −iq. The dq / 3-phase AC coordinate conversion unit 132 converts the d-axis voltage command value vd ^* and the q-axis voltage command value vq ^* based on the electrical angle θre of the rotor into a U-phase that is a value on the three-phase AC coordinate. It converts into voltage command value vu ^* and V phase voltage command value vv ^* . Then, the sign inversion adder 134 calculates the W-phase voltage command value vw ^* from the U-phase voltage command value vu ^* and the V-phase voltage command value vv ^* . The PWM signal generation circuit 150 receives the U-phase voltage command value vu ^* , the V-phase voltage command value vv ^* , and the W-phase voltage command value vw ^*, and the PWM signals Su and Sv whose duty ratio changes according to these command values. , Sw is generated. In the motor drive circuit 152, the switching elements are turned on / off by the PWM signals Su, Sv, Sw, so that the voltages vu, vv, vw corresponding to the duty ratio are changed to the U phase, V phase, W phase of the motor 6, respectively. Each is applied.

<3. Rudder angle abnormality determination process>
Next, the steering angle abnormality determination process in this electric power steering apparatus will be described. As described above, the rudder angle abnormality determination process according to the prior art is simple, and the accuracy of the determination result is not high. In the present embodiment, a first determination process and a second determination process are performed in order to detect an abnormality in the detected steering angle θ with high accuracy. In the first determination process, it is determined whether or not the steering wheel is in the neutral position based on the steering speed ωre, the vehicle speed V, and the steering torque Ts. Then, based on the average value of the detected steering angle θ during the period when the steering wheel is in the neutral position, it is determined whether or not an abnormality has occurred in the detection of the steering angle by the steering angle sensor 2. In the second determination process, the steering speed ωre is integrated for a predetermined time after the first determination process. Whether or not there is an abnormality in the detection of the steering angle by the steering angle sensor 2 based on the difference between the integrated value obtained by integrating the steering speed ωre for the predetermined time and the detected steering angle θ after the predetermined time has elapsed. Is determined. Hereinafter, the procedure of the steering angle abnormality determination process in the present embodiment will be described in detail with reference to the flowcharts shown in FIGS.

FIG. 3 is a flowchart showing the procedure of the steering angle abnormality determination process in the present embodiment. When driving of the motor is started, initial values of parameters in the steering angle abnormality determination process shown in this flowchart are set (step S10). In the steering angle abnormality determination process, the vehicle speed comparison value α, the steering speed comparison value β, the steering torque comparison value γ, the first integration time counter Cnt1, the second integration time counter Cnt2, the integration time Tt, and the first stage are parameters. period (first predetermined time) Ti1, a second stage time period (second predetermined time) Ti2, second stage permission flag Flg2, steering angle integration value S _theta, time average steering angle ave, steering speed integrated value theta _.omega.i, A first determination angle (first predetermined value) δ, a second determination angle (second predetermined value) e, a steering angle estimation error θe, and a steering angle abnormality flag Flgθ are used. Note that each parameter will be described later.

  After the end of step S10, step S12, step S14, step S16, and step S18 are sequentially executed. In each step, the steering speed ωre, the vehicle speed V, the steering torque Ts, and the steering angle θ are detected. As described above, after the steering speed ωre, the vehicle speed V, the steering torque Ts, and the steering angle θ are detected, it is determined whether or not the second stage permission flag Flg2 is “0” (step S20). Note that the second stage permission flag Flg2 is set to “0” in step S10 described above. Here, the second stage permission flag Flg2 is a flag indicating whether to perform the first determination process or the second determination process. If “0” is set, the first determination process is performed. If “1” is set, the second determination process is performed. If the result of determination in step S20 is that the second stage permission flag Flg2 is “0”, processing proceeds to step S21 and the first determination processing is performed. On the other hand, as a result of the determination, if the second stage permission flag Flg2 is not “0”, the process proceeds to step S22, and the second determination process is performed. FIG. 4 shows a flowchart showing the detailed procedure of the first determination process, and FIG. 5 shows a flowchart showing the detailed procedure of the second determination process.

  After step S21 (first determination process) or step S22 (second determination process), it is determined whether or not the steering angle abnormality flag Flgθ is “0” (step S90). Note that the steering angle abnormality flag Flgθ is set to “0” in step S10 described above. If the result of determination in step S90 is that the steering angle abnormality flag Flgθ is “0”, processing returns to step S12. On the other hand, if the steering angle abnormality flag Flgθ is not “0” as a result of the determination, an abnormality is dealt with as described later (step S92), and the process is terminated. In step S92, a signal indicating that the steering angle detected by the steering angle sensor 2 is abnormal is sent from the steering angle abnormality determination unit 170 to the target current setting unit 114. For example, control processing using the steering angle sensor 2 is performed. Stops.

<3.1 First determination process>
The first determination process will be described with reference to FIG. When the first determination process is started, first, it is determined whether or not the handle is in a neutral position (step S30). Here, conventionally, it is known that the neutral position of the steering wheel can be estimated based on the vehicle speed V, the steering speed ωre, and the steering torque Ts (see, for example, JP-A-2002-2516). Therefore, in the present embodiment, the vehicle speed V, the steering speed ωre, and the steering torque Ts are respectively compared with the vehicle speed comparison value α, the steering speed comparison value β, and the steering torque comparison value γ set in step S10. Specifically, with respect to the vehicle speed V, the steering speed ωre, and the steering torque Ts, it is determined that the steering wheel is in the neutral position if all the conditions shown in the following equations (1) to (3) are satisfied.
V> α (1)
| Ωre | <β (2)
| Ts | <γ (3)
Note that the steering speed ωre and the steering torque Ts are expressed with the right direction being positive and the left direction being negative. In step S30, in order to compare the magnitude of the steering speed ωre and the magnitude of the steering torque Ts with the steering speed comparison value β and the steering torque comparison value γ, respectively, the steering speed ωre and the steering torque in the above formulas (2) and (3). Ts is indicated by an absolute value.

  As a result of the determination in step S30, if all the conditions shown in the above equations (1) to (3) are satisfied, that is, if it is determined that the handle is in the neutral position, the process proceeds to step S32. On the other hand, if any one of the conditions shown in the above equations (1) to (3) is not satisfied, that is, if it is determined that the handle is not in the neutral position, the process proceeds to step S60. As described above, the neutral position determining means is realized by step S30.

  In step S32, “1” is added to the first integration time counter Cnt1. In order to determine whether or not the state in which the handle is in the neutral position has continued for a predetermined time, the first integration time counter Cnt1 is used in step S40 described later. The first integration time counter Cnt1 is set to “0” in the above-described step S10.

Next, an integrated value of the steering angle during a period in which the state where the steering wheel is in the neutral position continues is calculated. Specifically, "detected steering angle theta × calculation cycle Tk" is added to the steering angle integration value S _theta (step S34). Here, the calculation cycle Tk is a cycle in which the steering angle abnormality determination process shown in this flowchart makes one round (the time from the execution of step S34 to the execution of step S34 again), and is a value determined for each ECU. is there. Note that the steering angle integration value S _theta, is set with "0" in step S10 described above.

  Next, it is determined whether or not the state in which the steering wheel is in the neutral position has continued for a predetermined time (first stage period) in order to determine whether or not the detected steering angle θ is abnormal. Specifically, the first integration time counter Cnt1 described above is compared with the first stage period Ti1 whose value is set in step S10 (step S40). As a result, if the first integration time counter Cnt1 is greater than or equal to the first stage period Ti1, the process proceeds to step S42. On the other hand, if the first integration time counter Cnt1 is less than the first stage period Ti1, the first determination process is terminated, and the process proceeds to step S90 shown in FIG. For example, a value corresponding to a time of 1 to 2 seconds is set as the first stage period Ti1.

In step S42, the time average steering angle θave, which is the average value of the detected steering angle θ during the time during which the state where the steering wheel is in the neutral position (integration time Tt), is calculated by the following equation (4).
θave = S _θ / Tt (4)
The integration time Tt is calculated by the following equation (5).
Tt = (Cnt1-1) × Tk (5)
After calculating the time average steering angle θave is "0" is set to the first integration time counter Cnt1 (step S44), "0" is set to the steering angle integration value S _theta (step S46).

  Thereafter, it is determined whether or not the detected steering angle θ is abnormal. Specifically, the absolute value of the time average steering angle θave calculated in step S42 is compared with the first determination angle δ set in step S10 (step S50). By this step S50, the first abnormality detection means is realized. The first determination angle δ is set to “10 degrees”, for example. If the absolute value of the time average steering angle θave exceeds the first determination angle δ as a result of the comparison in step S50, “1” is set to the steering angle abnormality flag Flgθ (step S52). This means that although the steering wheel is in the neutral position, the detected steering angle θ does not indicate the neutral position, that is, there is an abnormality in the detection of the steering angle by the steering angle sensor 2. In this case, abnormality handling is performed as described above. On the other hand, if the absolute value of the time average steering angle θave is equal to or smaller than the first determination angle δ as a result of the comparison in step S50, “2” is set in the second stage permission flag Flg2 to proceed to the second determination process. (Step S54). When step S52 or step S54 ends, the process proceeds to step S90 shown in FIG.

A result of the determination in step S30, when the handle is determined not in the neutral position, "0" to the first integration time counter Cnt1 has been set (step S60), "0" to the steering angle integration value S _theta It is set (step S62). Thus, the next time the handle is ready to the neutral position, the steering angle and the integrated value S _theta in duration and the state of the state is added from zero. When step S62 ends, the process proceeds to step S90 shown in FIG.

<3.2 Second determination process>
Next, the second determination process will be described with reference to FIG. When the second determination process starts, “1” is added to the second integration time counter Cnt2 (step S70). In order to determine whether or not a predetermined time has elapsed after the first determination process, the second integration time counter Cnt2 is used in step S74 described later. The second integration time counter Cnt2 is set to “0” in step S10 described above.

Next, an integrated value of the steering speed ωre after the end of the first determination process is calculated. Specifically, "the steering speed? Re × calculation cycle Tk" is added to the steering speed integrated value theta _.omega.i (step S72). Thus, the steering angle of the steering wheel rotated after the end of the first determination process is indicated by the steering speed integrated value _θωi . As described above, the integrating means is realized by step S72. The calculation cycle Tk is a cycle in which the steering angle abnormality determination process shown in this flowchart makes one round, as in the first determination process. Further, “0” is set to the steering speed integrated value θ _ωi in the above-described step S10.

  Next, after the first determination process, it is determined whether a predetermined time (second stage period) has elapsed. Specifically, the second integration time counter Cnt2 described above is compared with the second stage period Ti2 whose value is set in step S10 (step S74). As a result, if the second integration time counter Cnt2 is greater than or equal to the second stage period Ti2, the process proceeds to step S76. On the other hand, if the second integration time counter Cnt2 is less than the second stage period Ti2, the second determination process ends, and the process proceeds to step S90 shown in FIG. For example, a value corresponding to “5 seconds” is set as the second stage period Ti2.

In step S76, the steering that is the difference between the integrated value θ _ωi of the steering speed ωre detected after the end of the first determination process and the detected steering angle θ detected by the steering angle sensor 2 after the second stage period Ti2 has elapsed. The angle estimation error θe is calculated by the following equation (6).
θe = θ−θ _ωi (6)
Further, “0” is set to the second integration time counter Cnt2 (step S78), “0” is set to the steering speed integrated value θ _ωi (step S80), and “0” is set to the second stage permission flag Flg2. It is set (step S82).

  Thereafter, it is determined whether or not the detected steering angle θ is abnormal. Specifically, the absolute value of the steering angle estimation error θe calculated in step S76 is compared with the second determination angle e set in step S10 (step S84). As a result, if the absolute value of the steering angle estimation error θe exceeds the second determination angle e, the steering angle abnormality flag Flgθ is set to “1” (step S86), and then the process proceeds to step S90 shown in FIG. . This means that the detected steering angle θ does not indicate the steering angle of the steering wheel that has actually rotated, that is, an abnormality has occurred in the detection of the steering angle by the steering angle sensor 2. In this case, abnormality handling is performed as described above. On the other hand, as a result of the determination in step S84, if the absolute value of the steering angle estimation error θe is equal to or smaller than the second determination angle e, the process proceeds to step S90 shown in FIG. As described above, the second abnormality detection means is realized by step S84.

<3.3 Relationship between handle movement and processing stage>
FIG. 6 is a diagram schematically showing the relationship among time, steering angle, and processing stage in the steering angle abnormality determination processing in the present embodiment. Hereinafter, the relationship between the movement of the steering wheel and the processing stage of the steering angle abnormality determination process will be described with reference to FIG.

  It is assumed that the first determination process is performed during the period indicated by Ta in FIG. 6 and the above-described equations (1) to (3) are satisfied. That is, during this period, the steering angle of the steering wheel is small and the steering wheel is continuously in the neutral position. In step S40, it is determined that “the first integration time counter Cnt1 is less than the first stage period Ti1” (No). .

  In FIG. 6, at the time indicated by Tb, the state where the handle is in the neutral position continues, and it is determined in step S40 shown in FIG. 4 that “the first integration time counter Cnt1 is equal to or greater than the first stage period Ti1” (Yes). Shows the time. At the time indicated by Tb, it is determined whether or not the detected steering angle θ is abnormal based on the time average steering angle θave that is the average value of the detected steering angle θ during the period indicated by Ta (step S50). .

  If it is determined in step S50 that the detected steering angle θ is not abnormal, a second determination process is performed. The second determination process is performed during a period indicated by Tc in FIG. During this period, in step S74 shown in FIG. 5, it is determined that “the second integration time counter Cnt2 is less than the second stage period Ti2” (No). FIG. 6 shows an example in which the steering angle of the steering wheel is increased during the period indicated by Tc. However, after the first determination process is completed, the second determination process is performed regardless of the change in the steering angle. Done.

  The time point indicated by Td in FIG. 6 is when it is determined in step S74 shown in FIG. 5 that “the second integration time counter Cnt2 is equal to or greater than the second stage period Ti2” (Yes). At the time indicated by Td, whether or not the detected steering angle θ is abnormal is determined based on the difference between the integrated value of the steering speed ωre of the steering wheel during the period indicated by Tc and the detected steering angle θ at the time indicated by Td. Determination is made (step S84).

  If it is determined in step S84 that the detected steering angle θ is not abnormal, the first determination process is performed again. In the period indicated by Te in FIG. 6, the handle gradually approaches the neutral position. During this period, in step S30 shown in FIG. 4, it is determined that “the handle is not in the neutral position” (No). The time point at which it is determined in step S30 that “the handle is in the neutral position” (Yes) is indicated by Tf in FIG. Further, during the period indicated by Tg in FIG. 6, the above-described equations (1) to (3) are satisfied, and the handle is continuously in the neutral position.

  In this way, the first determination process and the second determination process are repeated based on the operation of the vehicle. Accordingly, whether or not the detected steering angle θ is abnormal is determined by two determination processes as needed.

<4. Effect>
As described above, in the electric power steering device according to the present embodiment, during the operation of the motor, it is determined whether the steering angle detected by the steering angle sensor is abnormal by the following two determination processes. In the first determination process, whether or not the steering wheel is in the neutral position is determined independently of the detection of the steering angle by the steering angle sensor, and based on the average value of the detected steering angle in the state where the steering wheel is in the neutral position. It is determined whether or not the steering angle detected by the steering angle sensor is abnormal. In the second determination process, the steering angle detected by the rudder angle sensor is determined based on an error between the detected steering angle when a predetermined time has elapsed since the end of the first determination process and the integrated value of the steering speed at the predetermined time. It is determined whether or not there is an abnormality. Conventionally, an abnormality in the detected steering angle is detected only when the detected steering angle is larger than the maximum steering angle at which the steering wheel can be rotated, but in this embodiment, as described above, an abnormality in the detected steering angle at the neutral position is detected. An abnormality in the detected steering angle when the steering wheel is rotated is detected. Thereby, compared with the past, the accuracy of the abnormality detection of the steering angle detected by the steering angle sensor is increased. That is, an abnormality in the detected steering angle that has not been detected conventionally is detected. For this reason, the reliability of the control processing based on the steering angle detected by the steering angle sensor, such as the end-contact impact avoidance control, is increased, and the effect of the control processing is sufficiently drawn.

<5. Other>
Although the electric power steering apparatus using the brushless motor has been described in the above embodiment, the present invention is not limited to this. The present invention can be applied as long as the steering speed is detected by means other than the rudder angle sensor. For example, the present invention can also be applied to an electric power steering apparatus using a motor with a brush.

It is the schematic which shows the structure of the electric power steering apparatus which concerns on one Embodiment of this invention with the vehicle structure relevant to it. It is a block diagram which shows the structure which looked at the electric power steering apparatus which concerns on the said embodiment from a control viewpoint. It is a flowchart which shows the procedure of the steering angle abnormality determination process in the said embodiment. It is a flowchart which shows the procedure of the 1st determination process in the said embodiment. It is a flowchart which shows the procedure of the 2nd determination process in the said embodiment. It is the figure which showed typically the relationship between time, a steering angle, and a process step about the steering angle abnormality determination process in the said embodiment.

Explanation of symbols

2 ... Steering angle sensor 3 ... Torque sensor 4 ... Vehicle speed sensor 5 ... ECU (electronic control unit)
DESCRIPTION OF SYMBOLS 6 ... Brushless motor 10 ... Microcomputer 12 ... Position detection sensor 114 ... Target electric current setting part 142 ... Rotor angular velocity calculation part 162 ... Rotor angle position detector 170 ... Steering angle abnormality determination part

Claims (3)

A steering device for steering a vehicle in response to an operation by an operation means,
Torque detecting means for detecting steering torque applied to operating means for steering the vehicle;
Rudder angle detection means for detecting a steering angle which is an operation angle of the operation means;
Steering speed detection means for detecting the steering speed of the operation means independently of the steering angle detection means;
Rudder angle abnormality determining means for determining whether or not a detected steering angle that is a steering angle detected by the rudder angle detecting means is abnormal,
The rudder angle abnormality determining means is
Independently of the steering angle detection means, it is determined whether or not the operation means is in a neutral position, and based on the detected steering angle when it is determined that the operation means is in a neutral position, the detected steering angle First determination means for determining whether or not is abnormal,
A steering apparatus comprising: a second determination unit that determines whether or not the detected steering angle is abnormal based on the detected steering angle and a steering angle calculated from the steering speed. Vehicle speed detecting means for detecting the vehicle speed of the vehicle,
The first determination means includes
Neutral position determining means for determining whether or not the operating means is in a neutral position based on the vehicle speed, the steering speed, and the steering torque;
When it is determined by the neutral position determining means that the operating means is in the neutral position continuously for a first predetermined time, an average value of the detected steering angles at the first predetermined time is equal to or greater than a first predetermined value. If so, a first abnormality detection means for determining that the detected steering angle is abnormal,
The steering apparatus according to claim 1, comprising: The second determination means includes
Integrating means for calculating an integral value of the steering speed;
A second abnormality detecting means for determining that the detected steering angle is abnormal if a difference between the detected steering angle and the integrated value at a second predetermined time is equal to or greater than a second predetermined value;
The steering apparatus according to claim 1, wherein the steering apparatus includes:

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