JP2008265613A - Electric power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric power steering device capable of preventing a risk from occurring by rough operation by determining an abnormal traveling state in which rough steering and rough decelerating operation are performed by utilizing the result of the detection by generally mounted sensors. <P>SOLUTION: This electric power steering device comprises a torque sensor 4 for detecting a steering torque applied to a steering member, a vehicle speed sensor 7 for detecting the traveling speed of a vehicle, and an assist control device 6 for drivingly controlling a motor 5 for steering assistance according to the results of the detection by the torque sensor 4 and the vehicle speed sensor 7. The power steering device further comprises an abnormality determination part 61 for determining the abnormality of steering and the abnormality of deceleration by using the varying rate of the steering torque given from the torque sensor 4 through a differential calculation part 62 and a vehicle speed given from the vehicle speed sensor 7. The result of the determination by the abnormality determination part 61 is given, for example, to a navigation device 8 for alarming and displaying. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention is an electric motor configured to assist steering by applying a rotational force of a motor driven based on a detection result of a steering torque applied to a steering member and a detection result of a traveling speed of a vehicle to a steering mechanism. The present invention relates to a power steering device.

  An electric power steering device that drives a steering assist motor in response to a rotation operation of a steering member such as a steering wheel and assists steering by applying the generated force of the motor to a steering mechanism is a steering torque applied to the steering member. Is detected by a torque sensor, a target auxiliary force is determined based on the detected steering torque, and the motor is driven and controlled to generate the target auxiliary force.

  In such an electric power steering device, in order to obtain a better steering feeling, correction control for correcting the target auxiliary force according to the traveling state of the vehicle that affects the steering such as the vehicle speed and the yaw rate is widely performed. Yes.

On the other hand, in recent years, a driving support device has been proposed that monitors the running state of a vehicle, issues a warning for avoiding danger, and executes a driving support operation such as adjusting the vehicle speed by controlling an engine and a brake. (For example, refer to Patent Document 1). This device performs the above-described driving support operation based on the detection result directly related to the driving state of the preceding vehicle, the oncoming vehicle, the lane, etc., and causes the driver's attention to be reduced, thereby affecting the driving state. Paying attention to the operation of the in-vehicle device that is expected to exert, it is configured to generate a warning when this type of operation is performed.
JP 2003-127703 A

  In the invention disclosed in Patent Document 1, a navigation device, an air conditioner device, a mirror adjustment device, etc. are assumed as in-vehicle devices that cause a reduction in attention, and a warning is given when these operations are performed. A certain effect for realizing safe driving can be obtained.

  On the other hand, in the present invention, the response to steering and acceleration / deceleration, which are the most important operations for safe driving of the vehicle, is not assumed, and the driver's steering and acceleration / deceleration operations become complicated due to the accumulation of fatigue and the like. Although there is a risk of unexpected danger, it is difficult to prevent such danger from occurring.

  The present invention has been made in view of such circumstances, and by using the detection result of a sensor generally provided in an electric power steering apparatus, the occurrence of danger due to messy operations can be prevented in advance. With the goal.

  An electric power steering apparatus according to a first aspect of the present invention is based on a torque sensor that detects a steering torque applied to a steering member, a vehicle speed sensor that detects a traveling speed of a vehicle, and detection results of the torque sensor and the vehicle speed sensor. In the electric power steering apparatus comprising the steering assist motor driven by the motor, a sudden steering counting means for counting the number of times of sudden steering within a predetermined time based on the detection result of the torque sensor, and detection of the vehicle speed sensor Based on the result, the sudden deceleration counting means for counting the number of sudden decelerations within a predetermined time, and whether there is an abnormality based on the comparison result between the count value by the sudden steering counting means and the sudden deceleration counting means and the respective threshold values. An abnormality determining means for determining is provided.

  An electric power steering apparatus according to a second aspect of the present invention is characterized in that the threshold value in the first aspect is set for each travel route of the vehicle.

  In the electric power steering apparatus according to the first aspect of the invention, based on the detection result of the steering torque by the torque sensor, for example, the presence or absence of sudden steering is monitored from the torque change obtained as the differential value of the steering torque, and the traveling by the vehicle speed sensor is performed. Based on the detection result of the speed, for example, the presence or absence of sudden deceleration is monitored from the differential value of the vehicle speed, and when the number of sudden steering and sudden deceleration within a predetermined time exceeds a threshold value, an abnormal steering or deceleration state is entered. Therefore, the result of this determination is notified to the driver by appropriate means such as generation of warning sound, warning display, vibration of the steering member, etc. Can be prevented in advance.

  In the second invention, since different threshold values are set for each travel route, for example, it is possible to prevent unnecessary abnormality determination on a travel route that requires frequent steering, and to improve determination accuracy. it can. The travel route information for setting the threshold value may be given from the navigation device or may be given by the driver's operation. Further, it is desirable that the threshold value for each travel route is changed based on the past travel history on the same route.

  Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments thereof. FIG. 1 is a schematic diagram showing an overall configuration of an electric power steering apparatus according to the present invention. In addition, in this figure, although the example applied to a vehicle provided with the rack and pinion type steering mechanism 1 is shown, this invention is applicable regardless of the form of a steering mechanism.

  The rack-and-pinion type steering mechanism 1 crosses the rack housing 10 in the middle of the rack housing 10, which is supported in an axially movable manner in a rack housing 10 that extends in the left-right direction of a vehicle body (not shown). A pinion shaft 2 rotatably supported inside the pinion housing 20 is provided. Both ends of the rack shaft 11 are protruded to the outside of both sides of the rack housing 10, and these protruding ends are connected to left and right front wheels 13, 13 as steering wheels via respective tie rods 12, 12. . Further, the upper end of the pinion shaft 2 protruding outside the pinion housing 20 is connected to a steering wheel 30 as a steering member via the steering shaft 3.

  A pinion (not shown) is integrally formed at the lower part of the pinion shaft 2 extending inside the pinion housing 20, and this pinion has an appropriate length on the outer surface of the middle portion of the rack shaft 11 at the intersection with the rack housing 10. Is engaged with a rack provided. The steering shaft 3 is rotatably supported inside a cylindrical housing 31 and is attached to the interior of a passenger compartment (not shown) while maintaining a tilted posture with the front facing down via the housing 31. A pinion shaft 2 is connected to the protruding end of the steering shaft 3 downward, and a steering wheel 30 is fixed to the protruding end.

  With the above configuration, when the steering wheel 30 is rotated for steering, this rotation is transmitted to the pinion shaft 2 via the steering shaft 3, and the rotation of the pinion shaft 2 is caused by the meshing portion between the pinion and the rack. Is converted into the movement of the rack shaft 11 in the axial direction. The movement of the rack shaft 11 thus generated is transmitted to the left and right front wheels 13 and 13 via the respective tie rods 12 and 12, and the front wheels 13 and 13 are turned and steered.

  A torque sensor 4 for detecting a steering torque applied to the steering shaft 3 by the operation of the steering wheel 30 is provided in the middle of the housing 31 that supports the steering shaft 3. A steering assist motor 5 is provided below the torque sensor 4. Is installed.

  The torque sensor 4 divides the steering shaft 3 to be detected into two upper and lower axes that are coaxially connected by a torsion bar having a known torsion characteristic, and the torsion bar is twisted between these two axes. It has a known configuration for detecting the relative angular displacement by an appropriate means. The steering assisting motor 5 is attached to the outside of the housing 31 with its axis substantially orthogonal, and the rotation of the output shaft of the motor 5 extending inside the housing 31 is used to rotate the output shaft of the motor 5. Thus, the speed is reduced and transmitted to the steering shaft 3.

  The steering assisting motor 5 attached in this way is driven in accordance with a control command given from the assist control device 6 via a drive circuit (not shown). The assist control device 6 is given a detected value of the steering torque by the torque sensor 4 and a detected value of the vehicle speed by the vehicle speed sensor 7 arranged at an appropriate part of the vehicle.

  The assist control device 6 is connected to a navigation device 8 mounted on the vehicle so as to be able to exchange information via, for example, an in-vehicle LAN. The assist control device 6 performs an operation of obtaining information related to a travel route on which the vehicle is traveling from the navigation device 8 and giving a notification command to the navigation device 8 so as to notify the result of abnormality determination performed as described later. .

  FIG. 2 is a block diagram showing an internal configuration of the assist control device 6. Although the individual operation functions are shown as functional blocks in this figure, the actual assist control device 6 includes a CPU, a ROM, and a RAM, and the following assists are provided by the operation of the CPU according to the control program stored in the ROM. The ECU is configured to execute a control operation and an abnormality determination operation.

  The assist control device 6 includes an assist control unit 60 and an abnormality determination unit 61, and also includes a differential calculation unit 62 and a history storage unit 63. The detected value of the steering torque input from the torque sensor 4 is given to the assist control unit 60, and is also given to the assist control unit 60 and the abnormality determination unit 61 via the differential calculation unit 62. Further, the detected value of the vehicle speed inputted from the vehicle speed sensor 7 is given to the assist control unit 60 and the abnormality determination unit 61.

  The assist control unit 60 is an arithmetic control unit that performs an assist control operation with the steering assist motor 5 as a control target. This assist control operation takes in the detected value of the steering torque given from the torque sensor 4, applies this steering torque to a preset control map, and sets the target value (target assist force) of the steering assist force to be generated. This is a known operation in which a control command is issued to the steering assist motor 5 to drive and control the motor 5 in order to generate the target assist force.

  A plurality of control maps used for determining the target assist force are prepared according to the vehicle speed, and are selected and used according to the detected value of the vehicle speed taken from the vehicle speed sensor 7. As a result, the assist force characteristics can be made different according to the level of the vehicle speed. For example, when the road surface reaction force applied to the front wheels 13 and 13 is small, the steering assist force generated by the motor 5 is kept low, and the steering wheel 30 gives a sense of rigidity and realizes stable driving without wobbling, and conversely, when the road surface reaction force is large and when driving at low speed, the steering assist force is increased and the steering wheel 30 is operated easily. It becomes possible to reduce the labor burden required for steering.

  Further, the differential value of the steering torque given to the assist control unit 60 via the differential calculation unit 62, that is, the change speed of the steering torque is used for correcting the target auxiliary force determined as described above. This correction is made, for example, so as to decrease the target assist force in accordance with an increase in the change speed of the steering torque, and by this correction, the steering assist force generated in response to an abrupt operation of the steering wheel 30 is kept low, It is possible to suppress dangerous traveling caused by sudden steering.

  The abnormality determination unit 61 is connected to the navigation device 8. The navigation device 8 is configured to give information related to the travel route to the abnormality determination unit 61 and to display a predetermined warning in response to an abnormality notification command given from the abnormality determination unit 61. The alarm display by the navigation device 8 may be a message display on the display screen of the navigation device 8 or may be a voice display by a speaker. This alarm display can also be performed by dedicated alarm means provided separately from the navigation device 8.

  The abnormality determination unit 61 performs the following abnormality determination operation for determining a driver's abnormality using the change speed of the steering torque provided from the differential calculation unit 62 and the vehicle speed provided from the vehicle speed sensor 7. A history storage unit 63 is attached to the abnormality determination unit 61, and the history of the steering torque change speed and the vehicle speed that are sequentially applied is stored. The abnormality determination operation of the abnormality determination unit 61 is performed in the history storage unit 63. This is done with reference to the stored contents.

  FIG. 3 is a flowchart showing the operation content of the abnormality determination unit 61. The operation of the abnormality determination unit 61 according to this flowchart is repeatedly executed every predetermined control period in parallel with the assist control operation described above by the assist control unit 60.

  First, the abnormality determination unit 61 takes in the change rate ΔT of the steering torque given from the differential calculation unit 62 and the vehicle speed V given from the vehicle speed sensor 7 (step S1), and stores them in the history storage unit 63 (step S2). ).

  The history storage unit 63 sequentially stores ΔT and V given for each control opportunity, and stores them as time-series data for a predetermined time. Next, the abnormality determination unit 61 displays the current change rate. The storage data of the history storage unit 63 including ΔT and the vehicle speed V is read (step S3), the time series data of ΔT and V is referred to, the number of sudden steerings existing in the time series data of ΔT, and V The number of times of rapid deceleration existing in the time series data is counted (step S4), the current travel route given from the navigation device 8 is recognized (step S5), and a threshold value corresponding to the recognized travel route is set. Select (step S6).

  FIG. 4 is a diagram illustrating an example of time-series data of ΔT and V referred to in step S4. As shown in the figure, the change rate ΔT of the steering torque is given as data in which a peak corresponding to the magnitude of the change in the steering torque T at that time appears every time steering is performed. As shown, when a peak exceeding a predetermined size, for example, 30 Nm / sec, is determined that sudden steering has been performed. In step S4, the number of such peaks is counted as the number of sudden steerings.

  The vehicle speed V is given as data that increases or decreases according to the acceleration / deceleration performed during traveling. As indicated by B in the figure, the vehicle speed V is a rapid vehicle speed exceeding a predetermined magnitude, for example, (20 km / h) / second. It is determined that sudden deceleration has been performed when a decrease in the number of times occurs. In step S4, the number of such vehicle speed reductions is counted as the number of sudden decelerations.

  The threshold value selected in step S6 is a reference value used as a reference for abnormality determination, and for each of the travel routes, an average value obtained during the past travel for each of the number of times of sudden steering and sudden deceleration. Are sequentially updated and stored. If the travel route recognized in step S5 is the first travel route, a predetermined standard threshold value is selected.

  Next, the abnormality determination unit 61 compares the sudden steering and sudden deceleration count values in step S4 with the respective threshold values selected in step S6, and determines the presence or absence of abnormal steering and the presence or absence of abnormal deceleration based on the comparison result. (Steps S7, S8) When it is determined that there is abnormal steering or abnormal deceleration (step S7 or S8: YES), an abnormality notification command is issued to the navigation device 8 (step S9), and the navigation device When a series of operations is terminated by causing the predetermined warning display to be performed in FIG. 8 and it is determined that there is no abnormal steering and no abnormal deceleration (NO in steps S7 and S8), the abnormality notification operation is not performed. A series of operations are terminated.

  By the operation of the abnormality determination unit 61 described above, the steering torque change and the vehicle speed history within a predetermined time before the current time are referred to, and depending on the number of sudden steerings and the number of sudden decelerations appearing in this history It is determined whether or not an abnormal steering or deceleration operation is performed, and this result is notified by an alarm display of the navigation device 8, so that the driver is informed that the steering and deceleration operations are messy. Therefore, it is possible to prevent danger from occurring due to messy steering or acceleration / deceleration operations caused by accumulated fatigue.

  Since the threshold value used for the determination in steps S7 and S8 is selected for each travel route of the vehicle in steps S5 and S6, it is possible to improve the accuracy of the abnormality determination and to reduce the possibility of an unnecessary alarm display. it can. In a vehicle that does not include the navigation device 8, steps S5 and S6 may be omitted, and a determination may be made using a predetermined threshold, and the threshold is selected according to the driving route designation operation by the driver. It is good also as a structure to be. For example, the designation operation designates a type of travel route such as a mountain road, a highway, a general road, and the like.

  The alarm display by the navigation device 8 can be performed in an appropriate form such as a screen display of a warning message, generation of a warning sound, generation of a voice message, or a combination thereof. It is also possible to perform the abnormality determination in steps S7 and S8 step by step, change the type of abnormality notification command according to the degree of abnormality, and change the warning display form. It is also possible to give an abnormality notification command to an alarm means provided separately from the navigation device 8 and cause the alarm means to perform a predetermined alarm operation.

  The assist control device 6 shown in the embodiment is given from the torque sensor 4 at an intersection existing in the travel route set in the navigation device 8 by using the exchange of information with the navigation device 8, for example. The detected value of the steering torque is monitored, and other control operations related to steering, such as a route monitoring operation for performing appropriate notification when steering in a direction deviating from the set route is executed, are also performed. Can be configured.

  The notification in this case can also be performed by screen display or voice display in the navigation device 8, and further, the steering assist motor 5 is repeatedly rotated to vibrate the steering wheel 30 via the steering shaft 3. The driver who holds the steering wheel 30 may be directly informed of the possibility of off-route. The vibration of the steering wheel 30 can also be used as the above-described abnormal steering or abnormal deceleration notification means.

1 is a schematic diagram showing an overall configuration of an electric power steering apparatus according to the present invention. It is a block diagram which shows the internal structure of an assist control apparatus. It is a flowchart which shows the operation | movement content of an abnormality determination part. It is a figure which shows an example of the time-series data of the change speed of a steering torque, and a vehicle speed.

Explanation of symbols

  4 Torque sensor, 5 Motor, 6 Assist control device, 7 Vehicle speed sensor, 30 Steering wheel (steering member), 61 Abnormality determination unit (abnormality determination means)

Claims (2)

Electric power provided with a torque sensor for detecting a steering torque applied to the steering member, a vehicle speed sensor for detecting the traveling speed of the vehicle, and a steering assist motor driven based on the detection results of the torque sensor and the vehicle speed sensor In the steering device,
Sudden steering counting means for counting the number of times of sudden steering within a predetermined time based on the detection result of the torque sensor;
Sudden deceleration counting means for counting the number of sudden decelerations within a predetermined time based on the detection result of the vehicle speed sensor;
An electric power steering apparatus comprising: an abnormality determination unit that determines whether or not there is an abnormality based on a comparison result between the count values obtained by the sudden steering counting unit and the rapid deceleration counting unit and respective threshold values.   The electric power steering apparatus according to claim 1, wherein the threshold is set for each travel route of the vehicle.

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