JP2009012613A - Electric power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance forecasting accuracy of a dangerous driving state at low cost. <P>SOLUTION: The electric power steering device is provided with a danger determination part 142 for finally determining the dangerous driving state and giving warning to a driver when a danger driving notice is input from a navigation system when it is determined whether or not a steering pattern of the vehicle is in the dangerous state. When the vehicle speed V exceeds a predetermined threshold value, an angular velocity ω of an electric motor for steering assistance exceeds a predetermined threshold value and a variation ratio ΔT of the steering torque exceeds a predetermined threshold value, the danger determination part 142 determines that the steering pattern is in the dangerous state. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electric power steering apparatus that gives a warning to a driver when dangerous steering that predicts dozing is detected.

  In order to reduce the steering force of vehicles such as passenger cars and trucks, there is a so-called electric power steering (EPS) device that assists steering by a steering assist motor. In the EPS device, the driving force of the steering assist motor is applied to the steering shaft or the rack shaft by a transmission mechanism such as a gear or a belt via a speed reducer.

  By the way, also in this kind of EPS apparatus, the system which detects a dangerous driving | running state, such as falling asleep, and warns a driver | operator is proposed. In Patent Document 1, when the driver's arousal level is detected based on the movement of the driver's eyeball, brain wave, heart rate, blood pressure, etc., and the driver is in a reduced level of arousal level, the vehicle is in a specific running state (for example, On the condition that the vehicle speed is 40 to 100 km / h and the vehicle is in a straight traveling state), the warning mode is entered. In the warning mode, the steering actuator is maintained in the current state so that the traveling direction of the vehicle does not change and steering is performed. The member is vibrated to awaken the driver.

  In Patent Document 2, the deviation between the actual azimuth angle of the vehicle detected by the actual traveling direction detection means and the tangential direction azimuth angle of the road ahead obtained by the target traveling direction setting means using the information of the car navigation system is disclosed. In an electric steering apparatus that automatically controls an electric motor so as to be small, it is shown that a dozing state is detected by a wakefulness determination means, and the degree of automatic steering is increased as the wakefulness is lowered. The arousal level is determined from the appearance rate by counting the number of appearances per unit time of the steering torque having an amplitude exceeding a preset threshold value in the corrected steering frequency band.

JP 2004-34739 A JP 09-216567 A

  However, in Patent Document 1, since the driver's arousal level state is determined using only human body data such as eye movement, brain wave, heart rate, blood pressure, etc., the determination accuracy is low, and human body data is not stored. A detector for detection must be provided, and there is a problem that the cost is high. Further, in Patent Document 2, since the dozing state is detected only by the steering state that is the number of appearances of the steering torque per unit time, the detection accuracy of the dozing state is low, and there is a high possibility that the risk prediction is erroneous.

  The present invention has been made in view of the above, and an object of the present invention is to provide an electric power steering device that can improve the prediction accuracy of a dangerous driving state at low cost.

  In order to solve the above-described problems and achieve the object, the present invention controls the steering of the vehicle by driving and controlling the steering assist electric motor based on the steering assist command calculated based on the steering torque and the vehicle speed. In the assisting electric power steering apparatus, a steering determination unit that determines whether or not the steering pattern of the vehicle is in a dangerous state, an input unit that inputs a dangerous driving notification from an external device, and the steering determination unit are in a dangerous state. When a determination is made, if a dangerous driving notification is input to the input means, the vehicle is provided with a risk determining means for making a final determination of a dangerous driving state and giving a warning to the driver.

  According to a preferred aspect of the present invention, it is desirable that the external device is a navigation system.

  Further, according to a preferred aspect of the present invention, the steering determination means is configured such that the vehicle speed exceeds a predetermined threshold, the angular speed of the steering assist electric motor exceeds a predetermined threshold, and the steering torque fluctuation rate is a predetermined threshold. It is desirable to determine that the steering pattern is in a dangerous state when exceeding.

  Further, according to a preferred aspect of the present invention, it is desirable that the dangerous driving notification is generated when an overrun state of the traveling lane is detected.

  According to the electric power steering device of the present invention, when it is detected that the steering pattern of the vehicle is in a dangerous state, when dangerous driving notification is input from an external device such as a navigation system at this time, dangerous driving is performed. Since the state is finally determined and a warning is given to the driver, the prediction accuracy of the dangerous driving state can be improved at a low cost.

  Embodiments of an electric power steering apparatus according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

  FIG. 1 is a diagram illustrating a general configuration of an electric power steering (EPS) device 100. In FIG. 1, a column shaft 2 of a steering handle 1 is connected to a tie rod 6 of a steering wheel via a reduction gear 3, universal joints 4a and 4b, and a pinion rack mechanism 5. The column shaft 2 is provided with a torque sensor 10 that detects the steering torque T of the steering handle 1, and a steering assist motor 20 that assists the steering force of the steering handle 1 is connected to the column shaft via the reduction gear 3. 2 is connected. Here, the steering assist motor 20 is, for example, a brushless motor or a brush motor. The control unit (ECU) 30 that controls the electric power steering apparatus is supplied with electric power from the battery 14 via the built-in power supply relay 13 and is supplied with an ignition signal from the ignition key 11. Further, the control unit 30 calculates a current command value of the steering assist motor 20 based on the steering torque T detected by the torque sensor 10 and the vehicle speed (vehicle speed) V detected by the vehicle speed sensor 12, and steering assist is performed. Based on the detected current value of the motor 20 and the current command value, the steering assist motor 20 is driven and controlled so that the detected current value of the steering assist motor 20 follows the current command value.

  FIG. 2 is a diagram showing a hardware configuration of the control unit 30 of FIG. As shown in FIG. 2, the control unit 30 includes a power supply relay 13, an MCU (micro control unit) 110, a motor drive circuit 108, a current detection circuit 120, a position detection circuit 130, and the like.

  The MCU 110 includes a CPU 101, a ROM 102, a RAM 103, an EEPROM (nonvolatile memory) 104, an interface (I / F) 105, an A / D converter 106, a PWM controller 107, and the like, and these are connected by a bus. The CPU 101 executes various programs stored in the ROM 102 and controls the electric power steering apparatus.

  The ROM 102 is used as a memory for storing a control program for the steering assist motor 20 and a fail-safe function program, and the RAM 103 is used as a work memory for operating the program. The EEPROM 104 is a memory that can retain the stored contents even after the power is shut off, and can record a failure diagnosis result and the like.

  The A / D converter 106 inputs the steering torque T from the torque sensor 10, the current detection value Im of the steering assist motor 20 from the current detection circuit 120, the motor rotation angle signal θ from the position detection circuit 130, and the like. Convert to digital signal. The interface 105 is connected to an in-vehicle network such as CAN, and receives a vehicle speed signal V (vehicle speed pulse) from the vehicle speed sensor 12 and a dangerous driving notification E from a navigation system (hereinafter abbreviated as “navigation”) 50, as well as an alarm. A ringing command is output to the buzzer 60, and a dangerous driving notification F is output to the navigation 50.

  The PWM controller 107 outputs a PWM control signal for each phase of UVW based on the current command value of the steering assist motor 20. The motor drive circuit 108 is configured by an inverter circuit or the like, and drives the steering assist motor 20 based on a signal output from the PWM controller 107. The current detection circuit 120 detects the current value of the steering assist motor 20 and outputs the current detection value Im to the A / D converter 106. The position detection circuit 130 outputs an output signal from the position sensor 25 such as a resolver to the A / D converter 106 as a motor rotation angle signal θ.

  Hereinafter, the main part of a present Example is demonstrated. FIG. 3 shows a functional block diagram of the dangerous driving determination process performed by the CPU 101 in the MCU 110. The differentiator 140 differentiates the motor position signal θ output from the A / D converter 106 and outputs a motor angular velocity signal ω. The fluctuation rate calculation unit 141 receives the steering torque T from the A / D converter 106, and the fluctuation rate calculation unit 141 differentiates the steering torque T with respect to time so that the fluctuation amount of the steering torque T within a predetermined time. Torque fluctuation rate ΔT is calculated. In addition to the motor angular speed signal ω and the torque fluctuation rate ΔT, the danger determination unit 142 receives a vehicle speed signal V from the interface 105 and a dangerous driving notification E from the navigation 50. The danger determination unit 142 receives these input signals. Based on the above, a dangerous driving state that predicts a snooze driving is detected. When the danger determination unit 142 detects a dangerous driving state, the danger determination unit 142 outputs a ringing command to the alarm buzzer 60 via the interface 105 and outputs a dangerous driving notification F to the navigation 50. As described above, the danger determination unit 142 of the EPS device 100 detects a dangerous driving state in cooperation with the navigation 50.

  FIG. 4 shows a dangerous driving state that is likely to occur when the vehicle is traveling on the road. As shown in FIG. 4, when dozing, the vehicle gradually shifts laterally, and at the moment when the driver wakes up and notices that the driving lane protrudes (time point tc), the steering handle is turned back quickly and greatly, Cause wandering operation. Such a wobbling operation is likely to be repeated several times, resulting in a major accident. Therefore, in the first embodiment, such a large turning-back operation of the steering after protruding the driving lane is detected in cooperation with the navigation 50, and a warning is given to the driver, thereby reducing the possibility of a major accident. is doing.

  FIG. 5 shows temporal changes of various steering parameters during the dangerous driving shown in FIG. 4, and the time point tc corresponds to the time point tc in FIG. In this case, the steering parameters include a steering angle (motor position signal) θ as an output of the position detection circuit 130, a motor angular velocity ω that is a time derivative of the steering angle θ, and a steering torque T as an output of the torque sensor 10. The torque fluctuation rate (torque fluctuation amount at a predetermined time tg), which is a time derivative of the steering torque T, is shown. The danger determination unit 142 shown in FIG. 3 determines the dangerous driving state using the motor angular speed ω and the torque fluctuation rate ΔT among these four steering parameters.

  Next, details of processing in the risk determination unit 142 shown in FIG. 3 will be described using the flowchart of FIG. The danger determination unit 142 first determines whether or not the vehicle speed signal V is equal to or higher than a predetermined value (for example, 40 km / h) (step S200). If the vehicle speed signal V is smaller than the predetermined value, it is not in a dangerous state. A determination is made (step S240), and if the vehicle speed signal V is greater than or equal to a predetermined value, then a dangerous state of the vehicle running state is determined by analyzing the steering pattern (step S210).

  In the steering pattern analysis process in step S210, as described above, the dangerous driving state is determined using the motor angular velocity ω and the torque fluctuation rate ΔT among the four steering parameters shown in FIG. . That is, as shown in FIG. 5, the danger determination unit 142 determines that the vehicle is in a dangerous driving state when the motor angular velocity ω is greater than a predetermined threshold ωc and the torque fluctuation rate ΔT is greater than a predetermined threshold ΔTc. To do. Moreover, the danger determination part 142 determines with it not being a dangerous state, when both conditions of (omega)> (omega) c and (DELTA) T> (DELTA) Tc are not materialized (step S240).

  If the danger determination unit 142 determines that the vehicle is in a dangerous driving state in the steering pattern analysis process in step S210, next, whether or not the dangerous driving notification E is input to the EPS device 100 from the navigation 50 at this time. Is determined (step S220). In the navigation 50, when a dangerous driving state such as a lane protrusion is detected using the vehicle position information and the map information, a dangerous driving notification E is transmitted on the in-vehicle network. If the dangerous driving notification E is not input from the navigation 50 in step S220, the danger determination unit 142 determines that the determination in the steering pattern analysis process in step S210 is not a corresponding danger. It is determined that the vehicle is not in a dangerous driving state (step S240).

  However, if the dangerous driving notification E is input from the navigation 50 in step S220, the danger determining unit 142 finally determines that the vehicle is in a dangerous driving state (step S230), and the vehicle is dangerous. A dangerous driving notification F indicating that the vehicle is in a driving state is sent to the navigation 50 via the interface 105, and a sounding command is output to the alarm buzzer 60 via the interface 105 to cause the alarm buzzer 60 to sound to the driver. A warning is given (step S250). Further, when the EPS device 100 is provided with a mechanism for vibrating the steering, the danger determining unit 142 vibrates the steering and warns the driver (step S260).

  As described above, in the first embodiment, when the vehicle speed is equal to or higher than the predetermined value, the EPS device 100 determines whether or not the vehicle is in the dangerous driving state by analyzing the steering pattern and determines that the vehicle is in the dangerous driving state. In addition, when the dangerous driving notification is input from the navigation system 50, it is finally determined that the vehicle is in the dangerous driving state, and the dangerous driving determination on the EPS device 100 side and the danger in the navigation system 50 are performed. Since the EPS device 100 finally determines that the vehicle is in a dangerous driving state when the driving determinations match, the prediction accuracy of the dangerous driving state can be improved at low cost.

  In addition, during a drowsy driving, a large accident often occurs after several times of steering switchback operations after the running lane protrudes as shown in FIG. Therefore, in the first embodiment, the steering switchback after the running lane protrudes is accurately detected by using the vehicle speed V, the motor angular speed ω, and the torque fluctuation rate ΔT, and the detection information includes vehicle position and map information. Since the dangerous driving notification is added from the navigation system 50 that has detected the overrun of the driving lane, it is possible to more accurately detect the steering switchback steering after the overrun of the driving lane that oversees the drowsy driving, and to doze The possibility of preventing major accidents from driving increases. In other words, in the first embodiment, the navigation system 50 detects from the vehicle position and map information the protrusion of a driving lane that is likely to occur during a dozing operation, and the driving lane that is likely to occur during the dozing operation on the EPS device 100 side. When the large turnback of the steering after the overhang is detected and the detection outputs of these two coincide, the EPS device side finally determines that the vehicle is in a dangerous driving state, and predicts the dangerous driving state. Accuracy can be improved at low cost.

  In the above, the motor angular speed ω and the torque fluctuation rate ΔT are used to detect a fast large turn-back operation of the steering after the traveling lane protrudes, but other steering parameters such as the steering angle θ and the steering torque T are set. It may be used to detect a large turning-back operation with a fast steering after the running lane protrudes. Further, a dangerous steering pattern that predicts a snoozing operation may be detected by detecting a steering phenomenon other than a fast large turn-back operation of the steering after the traveling lane protrudes.

  Further, in the above, the dangerous driving notification for predicting dangerous driving is given from the navigation system 50 as an external device of the EPS device 100, and the determination in cooperation with the navigation system 50 is performed, so that the prediction accuracy of dangerous driving is improved. However, as the external device, an in-vehicle radar system using millimeter waves or microwaves or a dangerous driving monitoring system using a plurality of in-vehicle cameras may be adopted. In other words, when a dangerous driving monitoring system that uses a vehicle-mounted radar system or a vehicle-mounted camera to detect a drowsiness such as an overrun in a driving lane is detected, a dangerous driving notification is transmitted from these systems to the EPS device 100. In the EPS apparatus 100, when the dangerous driving is detected by itself, the dangerous driving state is finally reached when the dangerous driving notification is input from the dangerous driving monitoring system using the in-vehicle radar system or the in-vehicle camera. It may be determined that.

  Next, Embodiment 2 of the present invention will be described with reference to FIG. In the second embodiment, when the navigation system 50 determines the dangerous driving state using the information it has and the steering information from the EPS device 100 and detects the dangerous driving state, the EPS device 100 and the alarm buzzer 60 are detected. To be notified.

  That is, the EPS device 100 is configured to send steering information such as the motor angular velocity ω, the steering torque T, and the steering torque fluctuation rate ΔT to the navigation system 50 at regular time intervals via the in-vehicle network. In the navigation system 50 that has received the steering information, the vehicle speed determination and the steering pattern analysis as described in steps S200 and S210 of FIG. It is determined whether or not it is in a state. In addition, the navigation system 50 determines whether or not the vehicle is in a dangerous driving state such as a running lane protruding using the vehicle position information and the map information that the navigation system 50 has. Then, the navigation system 50 finally determines that the vehicle is in a dangerous driving state when both the determination results are in a dangerous state, gives a sounding command to the alarm buzzer 60 and causes the alarm buzzer 60 to sound. The apparatus 100 is notified that the vehicle is in a dangerous driving state. When notified of the dangerous driving state, the EPS device 100 vibrates the steering and gives a warning to the driver.

  In the second embodiment, the EPS apparatus 100 side uses the steering information such as the vehicle speed V, the motor angular velocity ω, and the steering torque fluctuation rate ΔT to determine the vehicle speed and the steering pattern as described in steps S200 and S210 in FIG. Analysis is performed to determine whether or not the vehicle is in a dangerous driving state, and when the dangerous driving state of the vehicle is detected, a dangerous driving notification indicating that fact is sent from the EPS device 100 to the navigation system 50. Good. In this case, when the navigation system 50 receives the dangerous driving notification from the EPS device 100, the navigation system 50 uses the vehicle position information and the map information that the navigation system 50 has to determine whether or not the vehicle is in a dangerous driving state such as a running lane protruding. When both determination results are in a dangerous state, it is finally determined that the vehicle is in a dangerous driving state.

  As described above, the electric steering device according to the present invention is useful for giving a warning to the driver when dangerous driving such as dozing is detected.

It is a figure showing the general composition of an electric steering device. It is a figure which shows the hardware constitutions of a control unit. It is a functional block diagram about dangerous driving judgment processing performed by CPU. It is a figure which shows the dangerous driving | running state of the vehicle which tends to wake up at the time of dozing driving. It is a figure which shows the time change of the various steering parameters at the time of the dangerous driving | running shown in FIG. It is a flowchart which shows the procedure of a dangerous driving | operation determination process. FIG. 3 is a diagram illustrating a system configuration of a second embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steering handle 2 Column shaft 3 Reduction gear 4a, 4b Universal joint 5 Pinion rack mechanism 6 Tie rod 10 Torque sensor 11 Ignition key 12 Vehicle speed sensor 13 Power relay 14 Battery 20 Steering auxiliary motor 25 Position sensor 30 Control unit 50 Navigation system 60 Alarm Buzzer 100 EPS device 110 MCU
101 CPU
102 ROM
103 RAM
104 EEPROM
DESCRIPTION OF SYMBOLS 105 Interface 106 A / D converter 107 PWM controller 108 Motor drive circuit 120 Current detection circuit 130 Position detection circuit 140 Differentiator 141 Fluctuation rate calculation part 142 Risk judgment part

Claims (4)

In an electric power steering device for assisting steering of a vehicle by controlling driving of an electric motor for steering assistance based on a steering assistance command calculated based on steering torque and vehicle speed,
Steering determination means for determining whether the steering pattern of the vehicle is in a dangerous state;
Input means for inputting a dangerous driving notification from an external device;
When the steering determination means determines that it is in a dangerous state, if a dangerous driving notification is input to the input means, a risk determination means that finally determines that the driving state is dangerous and gives a warning to the driver;
An electric power steering apparatus comprising:   The electric power steering apparatus according to claim 1, wherein the external device is a navigation system.   The steering determination means is configured such that a steering pattern is dangerous when the vehicle speed exceeds a predetermined threshold, the angular speed of the steering assist electric motor exceeds a predetermined threshold, and the fluctuation rate of the steering torque exceeds a predetermined threshold. The electric power steering apparatus according to claim 1, wherein the electric power steering apparatus is determined to be in a state.   The electric power steering apparatus according to any one of claims 1 to 3, wherein the dangerous driving notification is generated when a protruding state of a traveling lane is detected.

Images