JP4449464B2 - Control device for electric power steering device - Google Patents

Description

  The present invention relates to a control device for an electric power steering device, and more particularly, to an electric power steering device that can continue control using an alternative value when a torque sensor becomes abnormal and can reliably detect a failure of the torque sensor. The present invention relates to a control device.

  An electric power steering device that applies a steering assist force to a steering device of an automobile by the rotational force of a motor is a steering assist force applied to a steering shaft or a rack shaft by a transmission mechanism such as a gear or a belt via a speed reducer. Is supposed to be granted. A simple configuration of such an electric power steering apparatus will be described with reference to FIG. A shaft 102 of the steering handle 101 is connected to a tie rod 106 of a steering wheel via a reduction gear 103, universal joints 104a and 104b, and a pinion rack mechanism 105. The shaft 102 is provided with a torque sensor 107 that detects the steering torque of the steering handle 101, and a motor 108 that assists the steering force of the steering handle 101 is connected to the shaft 102 via the reduction gear 103. . The motor control of the electric power steering device is controlled by the control unit 109 using the torque value detected by the torque sensor 107, the vehicle speed detected by a vehicle speed sensor (not shown), the rotation angle of the motor detected by the hall sensor 110, etc. as input values. Is done. The control unit 109 is mainly a CPU, and motor control is executed by a program inside.

  FIG. 12 shows an example of a control block diagram of a motor for controlling the motor 108 of the electric power steering apparatus having such a configuration. In FIG. 12, the torque value detected by the torque sensor 107 is input, the current command value calculation unit 120 calculates the current command value Iref, the difference from the detected motor current value is calculated by the subtraction unit 121, and current control is performed. The duty ratio is determined by the unit 122, and the motor driving unit 123 drives the motor 108 by executing PWM control according to the duty ratio.

  In such an electric power steering apparatus, control of the electric power steering apparatus is executed on the assumption that the torque value detected by the torque sensor 107 is correctly detected. However, in actuality, when the torque sensor 107 also fails and an abnormal torque detection value is input, there is a risk of causing an abnormal operation with respect to the handle operation. Has been applied.

  For example, in Patent Document 1, a control method as shown in FIG. 13 is adopted to deal with an abnormality in the torque value output from the torque sensor. When the torque value output from the torque sensor becomes abnormal, if the abnormality continues for a certain time (tA), the auxiliary steering force command value that is the output value of the current control calculation based on the torque value is cut off. This is a control method in which the motor drive power supply is shut off when the abnormality continues for a longer period of time (tB). FIG. 14 shows the relationship between the torque value and the motor current when the torque sensor has a ground fault in such a control system and the torque value, which is the output of the torque sensor, becomes zero. In the case of this control method, since the calculation is performed based on the output value of the abnormal torque sensor during the determination time tA, the torque generated by the motor also becomes abnormal, and the steering wheel moves unintended by the driver. Furthermore, if the abnormality continues for the determination time (tB) or longer, the motor power supply is shut off. Therefore, if a large torque is applied to the handle, the torque changes suddenly, which is not preferable.

  As another countermeasure, there is a control method as in Patent Document 2. In Patent Document 2, when a serious abnormality such as a voltage drop or a momentary interruption of the torque sensor power supply occurs, the fail switch is opened, and the torque value that is the torque sensor output before the fail switch is opened is held. The auxiliary steering force command value is obtained by multiplying the held value by the output gain. Further, since the subsequent auxiliary steering force is controlled to gradually attenuate, the auxiliary steering force does not change suddenly. FIG. 15 shows the relationship between the torque value, which is the output of the torque sensor when the ground fault of the torque sensor fails, and the motor current when the control method of Patent Document 2 is used. The maximum negative current flows through the motor from the occurrence of the failure to the detection of the failure. However, since the motor current is gradually decreased from the torque immediately before the occurrence of the failure after the failure is detected, a sudden torque change as in Patent Document 1 occurs. do not do.

  However, when a ground fault occurs while the torque value as shown in FIG. 16 causes chattering, a value such as a black circle may be sampled when the output value of the torque sensor is sampled by the AD converter. If these values do not fall below the ground fault detection threshold, it cannot be detected that a ground fault has occurred, and the control is continued as it is. After the ground fault is detected, the motor current is gradually decreased from the torque value immediately before the occurrence of the failure, but chattering is caused to gradually decrease the motor current from the unstable torque value. Since the decrease starts from the reverse torque, it is not preferable.

JP 2000-318633 A JP 2000-329628 A

  When the torque value, which is the output of the torque sensor, becomes abnormal, in the conventional control method, the output torque of the motor becomes abnormal because control is performed based on the abnormal torque value until the torque sensor detects failure. . Further, even when a substitute value is used instead of an abnormal torque value, there is a problem that an appropriate substitute value is not calculated. As a result, when the output of the torque sensor becomes abnormal, the steering wheel moves unintended by the driver, and there is a problem that the driver feels uncomfortable with the steering wheel operation. Further, since an abnormal current flows through the motor during the failure period, the failure detection time cannot be made long, and as a result, there is a problem that erroneous detection is caused with respect to the failure detection of the torque sensor.

  The present invention has been made in the circumstances as described above, and the object of the present invention is to use an alternative value instead of the output value of the torque sensor even when the output value of the torque sensor becomes abnormal. A control device for an electric power steering device that ensures a safe handle operation without giving a sense of incongruity to the handle operation while ensuring a failure detection period long enough to prevent erroneous detection of a torque sensor failure. An object of the present invention is to provide a control device for an electric power steering apparatus that can safely switch between an output value of a torque sensor and an alternative value used in the event of an abnormality even when there are a plurality of detection means.

The present invention includes a motor that applies a steering assist force to a steering system of a vehicle, and a torque sensor that detects a steering force acting on a steering wheel, and controls the motor based on an output value of the torque sensor. The present invention relates to a control device for an electric power steering device, and the object of the present invention is to provide a plurality of torque abnormality detection means for detecting abnormality of the torque sensor based on an output value of the torque sensor, and an output value of the torque sensor. A substitute value calculating means for calculating a substitute value based on the past output value of a normal torque sensor before the abnormality becomes abnormal, and a period in which at least one of the plurality of torque abnormality detecting means continues to be judged as abnormal. when the predetermined time T1 or more, and a torque failure detection means for the torque sensor is determined it determines that the failure, even one of said plurality of torque abnormality detector different When determining that, when the motor is controlled based on the alternative value instead of the output value of the torque sensor, and the motor is controlled based on the alternative value, all of the plurality of torque abnormality detection means Is achieved by controlling using the output value of the torque sensor instead of the substitute value, and the torque failure detector detects that the substitute value is not updated during a predetermined time T2. This is achieved more effectively by establishing a determination that the torque sensor is faulty.

  The present invention includes a motor that applies a steering assist force to a steering system of a vehicle, and a torque sensor that detects a steering force acting on a steering wheel, and controls the motor based on an output value of the torque sensor. The present invention relates to a control device for an electric power steering device, and when the time period during which at least one of the plurality of torque abnormality detection means continues to determine abnormality is a predetermined time T1 or more, the torque sensor is in failure. This is achieved by confirming the determination.

  The present invention includes a motor that applies a steering assist force to a steering system of a vehicle, and a torque sensor that detects a steering force acting on a steering wheel, and controls the motor based on an output value of the torque sensor. The present invention relates to a control device for an electric power steering device, comprising a plurality of torque abnormality detection means for detecting abnormality of the torque sensor based on an output value of the torque sensor, and at least one of the plurality of torque abnormality detection means. This is achieved by confirming the determination that the torque sensor is in failure when the period for determining that it is abnormal continues for a predetermined time T3 or longer.

  When there are multiple torque abnormality detection means, if any one of them is determined to be abnormal, control is performed using the alternative value, and conversely, when returning to control with the output value of the torque sensor, all torque abnormalities are detected. When the detection means becomes normal, the value is switched from the substitute value to the output value of the torque sensor, so that the control device for the electric power steering device that can ensure safe control without being controlled with an abnormal torque value even instantaneously. Can be provided. In addition, when the substitute value is not updated during a predetermined time, it is determined that the torque sensor is faulty, so that the control by the substitute value does not continue for a long time. A control device of the apparatus can be provided.

  Further, even when the substitute value control is not executed, the plurality of torque abnormality detection units determine that the abnormality is abnormal, but even when the abnormal period alone does not continue for a long time, the outputs of the plurality of torque abnormality detection units are combined. If the abnormal period continues for a long time, in other words, if at least one of the plurality of torque abnormality detection means is determined to be abnormal, the determination that the torque sensor is faulty Therefore, it is possible to provide a control device for an electric power steering device that can reliably detect a torque sensor failure such as chattering and ensure safe control.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.
First, a case where there is one torque abnormality detection means will be described, and then an embodiment where a plurality of torque abnormality detection means according to the present invention will be described.

  FIG. 1 is a control block diagram showing an embodiment of the present invention. The torque value detected by the torque sensor 107 is not directly input to the current command value calculation unit 120 but is input to the torque input processing unit 10, and the output value is input to the current command value calculation unit 120. The current command value calculation unit 120 calculates the current command value Iref, the difference from the detected motor current value is calculated by the subtraction unit 121, the current control unit 122 determines the duty ratio, and the motor drive unit 123 sets the duty ratio. According to the PWM control, the motor 108 is driven.

  When the torque value output from the torque sensor 107 is normal, the torque input processing unit 10 operates so that the torque value is input to the current command value calculation unit 120. When the torque value is abnormal, the torque input processing unit 10 sets an alternative value. The alternative value is calculated and input to the current command value calculation unit 120.

  The torque input processing unit 10 includes a torque abnormality detection unit 10-1, an alternative value calculation unit 10-2, and a selection switch 10-4. The torque failure detection means 10-3 considers a failure if the output value of the torque sensor becomes abnormal and the abnormality continues for a certain time. The limiter 11 has a function of narrowing down the limiter value in order to gradually reduce the motor current (cut-off process) when the torque failure detection means 10-3 determines that a failure has occurred. The torque failure detection means 10-3 is not necessarily incorporated in the torque input processing unit 10. In this embodiment, since the output result of the torque abnormality detection means 10-1 is used, the torque failure detection means 10-3 is incorporated in the torque input processing unit 10. Further, the method of gradually decreasing the motor current is not limited to the limiter 11. For example, if the current command value Iref, which is the output of the current command value calculation unit 120, is multiplied by the gain G and the gain G is decreased from 1 to 0, the value of G · Iref gradually decreases from Iref to 0. Decrease towards

  The operation of the torque input processing unit 10 will be described with reference to the flowchart of FIG. The torque value T, which is the output value of the torque sensor 107, is read through the AD converter (S1). Next, it is determined whether the torque value T is normal or abnormal (S2). Various normal / abnormal determination values Tref are conceivable. For example, if a normal torque value is greater than or less than a threshold that is not possible, it is determined to be abnormal. Or, if it changes suddenly, it is considered abnormal. Torque value abnormalities include zero output voltage or a fixed power supply voltage, offset abnormalities (abnormalities that are biased by (T + α) and α), and torque amplifier abnormalities ((KT)). Abnormal or operational amplifier failure). If the torque value T is not abnormal, the abnormality detection counter is cleared (S3).

  This abnormality detection counter is counted when an abnormality in the torque value T is detected, and even if it is detected even once, it is not immediately determined that the torque sensor has failed. As will be described later, a torque sensor failure is determined only when the count value of the abnormality detection counter becomes equal to or greater than a set value. Next, the past torque value update routine is called to update the values T1, T2, T3, T4, and T5 of the previous n samples, for example, 5 samples as shown in FIG. 3 (S4). Since the torque value is not abnormal, the torque value T is calculated using the torque value as the torque input processing unit 10 (S5). Since the torque value T is not abnormal, the current command value calculation unit 120 calculates the current command value Iref based on the torque value T, not the substitute value.

  On the other hand, if it is determined in S2 that the torque value T is abnormal, the abnormality detection counter is counted up once (S6). Next, it is determined whether the count value N of the abnormality detection counter is equal to or greater than a set value (S7). If the count value is greater than or equal to the set value, it is determined that the torque sensor is malfunctioning. If the count value is less than or equal to the set value, it is not determined that the torque sensor has failed. However, since the torque value is abnormal, the torque value T cannot be used for the current command value calculation unit 120 as the output value of the torque sensor. Therefore, it is necessary to set an alternative value instead of the torque value T (S8).

  Here, the substitute value needs to be the current normal torque value predicted from the past torque value, and there are several methods for calculating the substitute value. The substitute value is calculated using n samples of past normal torque values. However, n is a natural number. For example, as shown in FIG. 4, an expected current value is obtained based on the values of five samples of past normal torque values, and is used as an alternative value (S11). In other words, the torque values of the past five samples are averaged, and the average value Tm = (T1 + T2 + T3 + T4 + T5) / 5 may be used as the substitute value. Other alternative value calculation methods will be described in detail later. Here, it is described that the normal torque value in the past is used, but this is ensured by the past torque value update routine which is the step of S4.

  Then, the substitute value is replaced as the torque value instead of the abnormal torque value (S9). And this alternative value is input into the electric current command value calculation part 120 as an output value of a torque sensor (S5). By controlling the motor with this alternative value, it is possible to avoid the output torque of the motor that was generated when the motor was controlled with an abnormal torque value.

  Another important point is that even before it is determined that the torque sensor is in failure, the abnormal torque value is not used for control, but is controlled using an alternative value. Conventionally, the motor was controlled by substituting an alternative value after it was determined that the torque sensor had failed, so before the failure was determined, control was performed based on the abnormal torque value, and the abnormal motor output torque was It was generated and the handle operation was uncomfortable.

  If the abnormality of the torque sensor continues, it is determined that the torque value is abnormal (S2), the abnormality detection counter is counted, and the count value is increased (S6). If the abnormality of the torque sensor further continues and the count value of the abnormality detection counter exceeds the set value N, it is determined that the torque sensor has failed (S7). If it is determined that the torque sensor has failed, a control for gradually decreasing the motor current is executed to prevent a sudden change in the output torque of the motor (S10). As a method of gradually attenuating the motor current, the alternative value is kept constant, the limiter 11 is provided at the output of the current command value calculation unit 120, and the limiter value of the limiter 11 is gradually reduced to gradually reduce the motor current. The motor current may be gradually attenuated by gradually decreasing the alternative torque value.

FIG. 5 is a diagram showing the relationship between the torque value that is the output of the torque sensor and the motor current when the output value of the torque sensor suddenly becomes zero, using the torque input processing unit 10 of the present embodiment. . Even if the torque value suddenly becomes zero, the substitute value is immediately used instead of the abnormal torque value, so that the motor current maintains the value immediately before the torque value becomes abnormal. The motor current maintains the previous value until it is determined that the torque sensor has failed, and the motor current gradually attenuates after it is determined that the torque sensor has failed. Compared with FIG. 14 and FIG. 15 of the results obtained by the conventional control method, the motor current does not reverse the polarity immediately before the torque value becomes abnormal, and the steering operation does not feel uncomfortable.

FIG. 6 shows the torque value (worst case) that is the output of the torque sensor when the output value of the torque sensor malfunctions due to chattering using the torque input processing unit 10 of this embodiment, and the motor current. The figure showing the relationship is shown. If the torque value causes chattering and it is determined that the torque value is abnormal, a substitute value is calculated using a past normal torque value, and the motor current is controlled based on the substitute value. Therefore, the motor current is output that is not significantly different from the motor current immediately before the chattering is generated. Furthermore, the motor current is gradually attenuated after the failure is detected. This result is compared with FIG. 16 which is a result of control by the conventional control method. In the case of the conventional control method, a motor current having a polarity opposite to that before the motor current becomes an abnormality in the torque sensor output is generated, and then the result is unfavorable for the driver. Although it is preferable to gradually attenuate the motor current after the failure is detected, it is not preferable because the motor current immediately before the attenuation is attenuated from the current having the opposite polarity. Obviously, the control method of this embodiment is more preferable for steering the steering wheel even in the worst case.

  The above is a description of the case where there is one torque abnormality detection means. Next, alternative value control when there are a plurality of torque abnormality detection means will be described with reference to FIG. The difference between the control block diagram of FIG. 1 and the control block diagram of FIG. 7 is that the torque sensor 107 A is added to the configuration of the torque input processing unit 10 and the torque sensor in addition to the torque sensor 107. That is, the torque sensor is composed of a dual system of the main torque sensor 107 and the sub torque sensor 107A.

First, an embodiment will be described in which the torque abnormality detection means is composed of a plurality of, for example, three types of torque abnormality detection means 10-1A, 10-1B , 10-1C. Torque abnormality detection means 10-1A detects whether the value of the main torque sensor is normal or abnormal. If the detection principle is normal, the output torque value Tm outputs a value between 1 and 4V, so that the output of 0 to 1V or 4 to 5V is abnormal. The control power supply voltage is 0-5V. Similarly, the torque abnormality detection means 10-1B detects whether the torque value Ts that is the output of the sub torque sensor is normal or abnormal. If the detection principle is normal, the output value is a value between 1 and 4V, so that the output of 0 to 1V or 4 to 5V is abnormal.

  Next, since the torque abnormality detection means 10-1C should originally show the same torque value, the torque value Tm that is the output of the main torque sensor 107 and the torque value Ts that is the output value of the sub torque sensor 107A, both torques If the value deviation ΔTr = | Tm−Ts | is equal to or greater than a predetermined value, it is determined that there is an abnormality. As another method for detecting an abnormality using the torque value Tm and the torque value Ts, although not shown, if the torque value Tm and the torque value Ts are normal, Tm + Ts = constant value or Tm−Ts = constant. There are anomaly detection methods that make use of characteristics such as values, and these methods may be used.

  Since the abnormal torque value is not used even for one cycle, the time for determining the abnormality is one cycle in the calculation by the CPU. For example, the determination is made in about 1 ms. Note that the output of the torque abnormality detection means 10-1A, 10-1B, 10-1C is “1” when abnormal, and “0” when normal.

  The selection switch 10-4 is controlled by the OR unit 10-5 and the AND unit 10-7. When the OR unit 10-5 outputs "1", that is, the torque abnormality detecting means 10-1A, 10-1B. , 10-1C, the selection switch 10-4 selects an alternative value, and the alternative value is sent to the current command value calculation unit 120.

  On the other hand, when the AND unit 10-7 outputs “1”, the selection switch 10-4 selects a torque value Tm that is a detection value of the torque sensor 107. That is, when all the outputs of the abnormality detection means 10-1A, 10-1B, 10-1C output normal "0", they are inverted by the NOT units 10-6A, 10-6B, 10-6C, and the AND unit 10 The inputs of −7 are all “1”, so the output of the AND section 10-7 is “1”, and the selection switch 10-4 selects the torque value Tm.

  The reason why such a control method is adopted is for safety, and if the torque value that is the output of the torque sensor is determined to be abnormal even by one torque abnormality detection means, the electric power steering device is controlled with an alternative value, On the contrary, if the condition for returning the control from the substitute value to the torque value that is the output of the torque sensor is that all the torque abnormality detection means are determined to be normal, the control of the electric power steering device can be secured safely. It is.

  The above explanation is a case where it is determined that there is an abnormality based on the output value of the torque sensor. However, if the torque value used for the control is replaced with an alternative value, the control of the electric power steering apparatus can be continued with the alternative value. Is the case. However, if the torque value abnormality continues for a predetermined time T1, for example, about 30 ms, it is necessary to determine that it is a serious failure of the torque sensor and control.

Hereinafter, the determination of the failure of the torque sensor will be described with reference to FIG. In FIG. 7, the failure of the torque sensor is realized by the torque failure detection means 10-3. The torque failure detection means 10-3 outputs the outputs from the plurality of torque abnormality detection means 10-1A, 10-1B, 10-1C, respectively, as lag portions (hereinafter referred to as TD) 10-3A , 10-3B, 10-. 3C, the outputs of TDs 10-3A, 10-3B, and 10-3C are input to the OR unit 10-3, and the output of the OR unit 10-3D becomes a failure determination result. TD is realized by a counter or the like when a CPU is used as a control device.

  The failure detection means 10-3A determines that the torque sensor is in failure when the abnormality “1”, which is the output of the torque abnormality detection means 10-1A, continues for a certain period of time, for example, a predetermined time T1 of 30 ms or more. Determine. Similarly, if the abnormality “1”, which is the output of the torque abnormality detecting means 10-1B, continues for a certain period of time, for example, 30 ms, which is the predetermined time T1, the failure detecting means 10-3B is in trouble. Confirm that there is. The failure detection means 10-3C determines that the torque sensor is in failure when the abnormality “1”, which is the output of the torque abnormality detection means 10-1C, continues for a certain time, for example, the predetermined time T1 of 40 ms. To do. In the OR section 10-3D, if any one of the TDs 10-3A, 10-3B, and 10-3C outputs “1”, “1” is output, and the determination that the torque sensor is in failure is confirmed. .

  That is, when one of the torque abnormality detection means in the torque abnormality detection means 10-1A, 10-1B, 10-1C continues to be abnormal independently for a predetermined time or more, the torque sensor has failed. Confirm the decision. Since the TD setting time T1 varies depending on the detection principle of the torque sensor abnormality, the TDs 10-3A, 10-3B, and 10-3C may have different setting times T1.

  Next, as a condition for determining that the torque sensor is in failure, the case where the time that the torque abnormality detecting means determines that abnormality has continued for a certain period of time has been described, but there are other phenomena that must be determined as failure of the torque sensor. To do. This phenomenon will be described with reference to FIG.

  Torque abnormality detection means 10-1A determines abnormality of the torque value Tm of the main torque sensor 107, and the detection principle is normal "0" when the output is 1 to 4V, and 0 to 1V or 4 to 5V is abnormal. It is determined as “1”. Further, the torque abnormality detection means 10-1C determines that the abnormality is detected when the deviation ΔTr = | Tm−Ts | between the output value Ts of the main torque sensor 107 and the sub torque sensor 107A is equal to or greater than a predetermined value.

  Based on such a detection principle, a case is assumed where the output cable of the main torque sensor 107 has a disconnection failure or a connector failure. When the output cable is disconnected, observing a short time of about 100 ms before and after the disconnection, the output value Tm of the torque sensor 107 input to the torque input unit 10 is hunting between 0V and 5V in a very short repetition. The phenomenon occurs. One example is the time chart of FIG. Torque abnormality detection means 10-1A is chattering in which the torque value Tm goes up and down between 0 and 5V. Therefore, the abnormality is "1" at 0 to 1V, normal "0" at 1 to 4V, and abnormality "1" at 4 to 5V. The output shown in FIG.

  On the other hand, when the torque value Tm of the main torque sensor goes up and down around 2.5V, for example, when the sub torque sensor 107A is 2.5V which is a neutral point as the torque value, the torque abnormality detecting means 10-1C is normal “0”. Therefore, when the voltage approaches 0V or 5V, an abnormality “1” is output. Accordingly, the output of the torque abnormality detection means 10-1C is as shown in FIG. 8B, and becomes “1” and “0” signals which are alternately different from the “1” and “0” signals in FIG. 8A. . If the tolerance for the deviation ΔTr is large, as shown in FIG. 8, the torque abnormality detection means 10-1C changes from normal to abnormal before the torque abnormality detection means 10-1A switches from abnormality to normal, for example, for a long time. For about 50 ms, all the torque abnormality detection means 10-1A, 10-1B, 10-1C do not become normal, and the alternative value control is continued for 50 ms for a long time.

  When this phenomenon is replaced with steering wheel operation, control continues based on the substitute value when the steering wheel is turned to the left at high speed, and when it is necessary to turn the steering wheel to the right, the assist is continued to the left. Means that. This is an undesirable phenomenon. Therefore, the torque sensor should be determined to be faulty and switched to the next best control method such as manual operation.

  A torque failure detection means for coping with such a phenomenon will be described with reference to FIG. Torque failure detection means 10-3Y and torque failure detection means 10-3Z are added to the torque input processing unit 10.

  First, the torque failure detection means 10-3Y comprised of the comparison unit 10-3E and TD10-3F will be described. The comparison value 10-3E compares the input value to the current command value calculation unit 120 and the substitution value output from the substitution value calculation unit 10-2, and determines whether or not the substitution value has been updated. Then, if the comparison result of the comparison unit 10-3E is input to the TD10-3F and the substitute value is not updated for a predetermined time T2 set by the TD10-3F, for example, 50 ms or more, it is determined that the torque sensor is in failure. Confirm.

Next, the torque failure detection means 10-3Z composed of TD10-3G will be described. An output of the OR unit 10-5 indicating a substitute value selection command is input to the TD 10-3G. And if the period which continues and selects an alternative value continues for the predetermined time T3 which TD10-3G sets, for example, 60 ms or more, determination that a torque sensor is out of order will be decided. In other words, if the alternative value control continues for a long time, it means that the torque sensor is determined to be faulty. The difference between the torque failure detection means 10-3Z and the torque failure detection means 10-3 is that the torque failure detection means 10-3 is one of the torque abnormality detection means 10-1A, 10-1B, 10-1C. However, if the period of abnormality alone is continued for a long period of time T1, the determination that the torque sensor is faulty is confirmed. On the other hand, the torque failure detection means 10-3Z has a shorter period of time when the torque abnormality detection means 10-1A, 10-1B, 10-1C are abnormal independently, such as an abnormality in the chattering state. When combined, there is a difference that a failure of the torque sensor in which the abnormality continues for a long time can be detected.

The OR unit 10-3H is for collecting failure detection results of all torque sensors. In this embodiment, the failure of the torque failure detection means 10-3 and the torque failure detection means 10-3Y and 10-3Z. The determination result is input.

  In this way, a special failure phenomenon that occurs when the wiring from the torque sensor is disconnected is reliably detected, and the alternative value control that replaces the torque value from the torque sensor does not continue for a long time. In the case of a failure, it becomes possible to control the electric power steering device with safe control such as manual control.

  In the above description, the case where the average value of the past torque is used as the substitute value has been described. However, the present invention can be applied even if the past torque value is weighted or the substitute value obtained by the least square method is used. It is possible to apply.

  In the above invention, the case where the alternative value control is performed has been described, but the second invention when the alternative value control is not executed will be described with reference to FIG.

  Torque sensor failures occur without executing alternative value control, and it is necessary to detect them reliably. However, conventionally, when the torque failure detection means 10-3 in FIG. 10, that is, the torque failure detection means using the TDs 10-3A, 10-3B, and 10-3C, is independently abnormal for a long time. For example, if the torque sensor continues for more than time T1, the determination that the torque sensor is in failure has been confirmed. However, as described with reference to FIG. 8, the plurality of torque abnormality detection units 10-1A, 10-1B, and 10-1C have a short period during which the single torque abnormality detection unit is abnormal like chattering. However, when the torque abnormality detection means 10-1A, 10-1B, 10-1C are combined, the abnormality that the abnormality period continues for a long time is not related to the alternative value control, and the conventional torque sensor failure Could not be detected.

  However, as shown in FIG. 10, by combining the torque abnormality detection means 10-1A, 10-1B, 10-1C, the OR unit 10-5, and the TD10-3G, a plurality of torque abnormality detection means can be obtained. Like chattering, the period that is abnormal by itself is short, but when the torque abnormality detection means 10-1A, 10-1B, 10-1C are combined, the period that is abnormal is long, for example, the predetermined period T3. It is possible to reliably detect an abnormality that continues as described above and obtain an effect that can be determined as a failure of the torque sensor.

  Therefore, if the second aspect of the invention is used, the plurality of torque abnormality detection means are independent for a short period of time, such as chattering, where the plurality of torque abnormality detection means are abnormal independently, but the plurality of torque abnormality detection means When combined, it reliably detects an abnormality that lasts for a long period of time, in other words, an abnormality that causes at least one of the plurality of torque abnormality detection means to be judged to be abnormal for a predetermined time or longer. Thus, there is an effect that it is possible to provide a control device for an electric power steering device that can be determined as a failure of the torque sensor and that can perform a steering operation with a good feeling by executing control corresponding to the failure.

It is a control block diagram of an electric power steering device. It is a flowchart which shows operation | movement of a torque input process part. It is a flowchart of the update operation | movement of a past torque value. It is a flowchart which substitutes the present value estimated from the past torque value as a substitute value. It is a figure which shows the output result of the motor current at the time of a torque sensor ground fault failure. It is a figure which shows the output result of the motor current at the time of the failure which caused the chattering phenomenon in the torque sensor. It is a control block diagram provided with the multiple torque abnormality detection means which concerns on this invention. It is an output time chart of each torque abnormality detection means at the time of a torque sensor abnormality. It is a control block diagram provided with a torque sensor failure detection means using alternative value control according to the present invention. It is a control block diagram provided with a torque sensor failure detection means that does not use alternative value control according to the present invention. It is a figure which shows the structure of an electric power steering apparatus. It is a control block diagram of the conventional electric power steering device. It is a control block diagram of the conventional electric power steering device corresponding to a torque sensor ground fault It is a figure which shows the output result of the motor current by the conventional control at the time of a torque sensor ground fault failure It is a figure which shows the output result of the motor current by the conventional improved control at the time of a torque sensor ground fault failure. It is a figure which shows the output result of the motor current by the conventional control at the time of a torque sensor chattering failure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Torque input process part 10-1 Torque abnormality detection means 10-1A, 10-1B, 10-1C Torque abnormality detection means 10-2 Alternative value calculation means 10-3, 10-3Y, 10-3Z Torque failure detection means 10 -4 Selection switch 10-5, 10-3H OR section 10-6 NOT section 10-7 AND section 10-3A, 10-3B, 10-3C, 10-3F, 10-3G Delay section (TD)
10-3E Comparison unit 11 Limiter 107 Torque sensor 108 Motor 120 Current command value calculation unit 121 Subtraction unit 122 Current control unit 123 Motor drive unit

Claims (4)

An electric power steering apparatus comprising: a motor that applies a steering assist force to a steering system of a vehicle; and a torque sensor that detects a steering force acting on a steering wheel, and controls the motor based on an output value of the torque sensor. A plurality of torque abnormality detecting means for detecting abnormality of the torque sensor based on the output value of the torque sensor, and the output of the past normal torque sensor before the output value of the torque sensor becomes abnormal. When the substitute value calculating means for calculating the substitute value based on the value and the time period during which at least one of the plurality of torque abnormality detecting means continues to be determined to be abnormal is the predetermined time T1 or more, the torque sensor has failed. and a torque fault detection means for determining determines that there, when it is determined that even one abnormality in the plurality of torque abnormality detecting means, an output of said torque sensor When the motor is controlled based on the alternative value and the motor is controlled based on the alternative value, when it is determined that all of the plurality of torque abnormality detection means are normal, the alternative value is set. Instead, a control device for an electric power steering device, wherein control is performed using an output value of the torque sensor. 2. The control device for an electric power steering apparatus according to claim 1, wherein the torque failure detection means determines that the torque sensor is in failure when the substitute value is not updated during a predetermined time T <b> 2. An electric power steering apparatus comprising: a motor that applies a steering assist force to a steering system of a vehicle; and a torque sensor that detects a steering force acting on a steering wheel, and controls the motor based on an output value of the torque sensor. The control device includes a plurality of torque abnormality detection means for detecting abnormality of the torque sensor based on an output value of the torque sensor, and even if one of the plurality of torque abnormality detection means continues independently, it is determined as abnormal. A control device for an electric power steering device, wherein when the time period to perform is equal to or greater than a predetermined time T1, the determination that the torque sensor is in failure is fixed. An electric power steering apparatus comprising: a motor that applies a steering assist force to a steering system of a vehicle; and a torque sensor that detects a steering force acting on a steering wheel, and controls the motor based on an output value of the torque sensor. In the control device, a plurality of torque abnormality detection means for detecting abnormality of the torque sensor based on an output value of the torque sensor, and a period for determining that at least one of the plurality of torque abnormality detection means is abnormal Is determined for the failure of the torque sensor when the predetermined time T3 is equal to or longer than the predetermined time T3.

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