JP2005343183A - Abnormality detection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an abnormality detection device capable of accurately determining abnormality of control of predetermined function of a vehicle even when permitted communication interruption is generated in a communication system. <P>SOLUTION: The abnormality detection device is provided with a traveling state detection means for detecting the predetermined traveling state of the vehicle; a control controller for controlling predetermined function of the vehicle; an instruction value determination means for determining an instruction value for controlling the predetermined function based on the vehicle traveling state by the control controller; and a communication means for communicating the instruction value determined by the instruction value determination means from the instruction value determination means to the control controller by a communication method for permitting the communication interruption. The control controller is characterized in that it changed a predetermined threshold value (S200-S235) in response to the number of interruptions generated between the former instruction value and the present instruction value when deviation of the former instruction value formerly received and the present instruction value received at present is compared with the predetermined threshold value to detect the abnormality of the predetermined function. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an abnormality detection device that can detect an abnormality more accurately and accurately when detecting an abnormality of a predetermined function using a communication means that allows communication interruption in a vehicle.

An anomaly detection device that captures the front of a vehicle with a camera, detects the travel route of the vehicle based on the captured image or video, and assists driving so that the vehicle does not deviate from the travel route is known. Has also begun to be installed. Such an anomaly detection device is called a lane keeping control or device lane keeping (assist) system. There is one that turns by an actuator (helps turning) and corrects the deviation of the travel route. Examples of the latter include those described in [Patent Document 1] below.
JP 2001-10518 A

  In the control described in the above publication, the steering torque necessary for the lane keeping control is communicated by a network constructed on the vehicle, and finally drives the actuator. For communication on the vehicle, a communication system that allows communication interruption, such as a CAN communication system, can be used. However, the above-mentioned publication does not describe detection of abnormality, and it is necessary to consider this communication interruption when determining abnormality of lane keeping control. If this communication interruption is not taken into consideration, it is considered that the communication interruption permitted in the communication system has just occurred and it is immediately determined to be abnormal. Accordingly, an object of the present invention is to detect an abnormality that can accurately determine whether or not an abnormality has occurred in the control of a predetermined function of the vehicle even when an allowable communication interruption occurs in the communication system. To provide an apparatus.

  The abnormality detection device according to claim 1 is based on a traveling state detection unit that detects a predetermined traveling state of the vehicle, a controller that controls a predetermined function of the vehicle, and a vehicle traveling state detected by the traveling state detection unit. The command value determining means for determining the command value for controlling the predetermined function by the controller and the command value determined by the command value determining means from the command value determining means by the communication method allowing communication interruption from the command value determining means to the control controller. A communication means for communicating with the controller, and when the controller detects an abnormality of a predetermined function by comparing a deviation between the previous command value received last time and the current command value received this time with a predetermined threshold value, The predetermined threshold value is changed according to the number of interruptions occurring between the command value and the command value.

  Note that the number of interruptions referred to here includes a case where the predetermined threshold is different between when there is no interruption and when there is an interruption. In addition, the number of interruptions includes a case where the predetermined threshold is different between when there is no interruption and when there is only one interruption. Further, for example, the number of interruptions includes a case where the predetermined threshold values are all different between when there is no interruption and when there is only one interruption and when there are two interruptions. The predetermined threshold value may be different between when the interruption is once and twice and when the interruption is three or more times. That is, the method of changing the predetermined threshold is not limited.

  According to a second aspect of the present invention, in the abnormality detection device according to the first aspect, the traveling state detecting means detects the position of the vehicle with respect to the traveling route based on a front image acquired by imaging the front of the vehicle. And the predetermined function is to apply a steering torque to the steering mechanism based on the detected vehicle position with respect to the detected travel route to cause the vehicle to travel on the desired travel route. Is calculated, and the controller determines that it is abnormal when the deviation between the previous steering torque, which is the previous command value, and the current steering torque, which is the current command value, is greater than a predetermined threshold value. Therefore, the predetermined threshold value is set larger as the number of interruptions between the previous steering torque and the current steering torque is larger.

  According to the abnormality detection device of claim 1, the abnormality is detected more accurately and accurately by changing the predetermined threshold value used for abnormality determination according to the number of communication interruptions that occur, taking into account the influence of communication interruption. can do. For example, when communication interruption occurs, the deviation between the previous command value and the current command value becomes larger than usual. However, if it is determined that there is an abnormality by comparing a large deviation with a predetermined threshold without considering that the interruption has occurred, there is a high possibility that the abnormality is determined to be normal. . On the other hand, if a predetermined threshold value is secured large in consideration of communication interruption, it is determined that the communication is normal even when communication interruption does not occur (a situation where the magnitude of the deviation does not increase so much). there is a possibility. The present invention can detect an abnormality more accurately and accurately by changing a predetermined threshold value used for abnormality determination according to the number of communication interruptions that have occurred.

  The abnormality detection device according to claim 2 is an abnormality detection device related to a vehicle that steers the vehicle according to a forward path of the vehicle. In this device, the predetermined value described above is the steering torque applied to the steering mechanism. Here, the change amount of the steering torque is limited by the above-described predetermined threshold value, and it is determined that it seems to exceed the predetermined threshold value. However, if communication interruption occurs, one or more command values are missing, so the above-described deviation (amount of change in steering torque) may increase. Therefore, in such a case, the larger the number of interruptions, the larger the predetermined threshold (in other words, the predetermined threshold will not be relaxed if there are few interruptions), and a predetermined threshold corresponding to the number of interruptions is set. Thus, the abnormality can be detected more accurately and accurately.

  An embodiment of the abnormality detection apparatus of the present invention will be described below. FIG. 1 shows a configuration diagram of a vehicle 1 provided with the abnormality detection device of the present embodiment. The abnormality detection device of this embodiment detects an abnormality of the lane keeping control device. First, the lane keeping control device will be described. The vehicle 1 includes an electronic control unit (ECU: Electric Control Unit) 2 for steering assistance (lane keeping control), and driving assistance (lane keeping control) is controlled by the steering assistance ECU 2. The steering assist ECU 2 also cooperates with an EPS-ECU 14 to be described later, and also takes part in the control of an electronically controlled power steering mechanism (EPS).

  As shown in FIG. 1, the vehicle 1 includes a steering wheel 3. The steering wheel 3 is disposed in the vehicle interior of the vehicle 1 and steers steered wheels (here, left and right front wheels FR, FL) when operated by a driver. The steering wheel 3 is fixed to one end of the steering shaft 4. The steering shaft 4 rotates as the steering wheel 3 rotates.

  A rack bar 6 is connected to the other end of the steering shaft 4 via a steering gear box 5. The steering gear box 5 has a function of converting the rotational movement of the steering shaft 4 into the linear movement of the rack bar 6 in the axial direction. Both ends of the rack bar 6 are connected to the hub carriers of the wheels FL and FR via the knuckle arm 7. Because of this configuration, the wheels FL and FR are steered via the steering shaft 4 and the steering gear box 5 (rack bar 6) when the steering wheel 3 is rotated.

  In addition, a CCD camera 8 that images the front is built in the rearview mirror. The CCD camera 8 photographs the surrounding situation in a predetermined area in front of the vehicle 1. An image processing unit 9 is connected to the CCD camera 8. The image data of the surrounding situation photographed by the CCD camera 8 is supplied to the image processing unit 9. The image processing unit 9 performs image processing on image data from the CCD camera 8 and detects a lane (lane: travel route) based on a white line drawn on a road on which the vehicle 1 travels. In the captured image or video, the brightness difference between the road surface and the white line drawn thereon is large, and the white line is relatively easy to detect, which is convenient for detecting the lane ahead of the vehicle.

  The image processing unit 9 is connected to the steering assist ECU 2 described above. The image processing unit 9 detects the curve curvature (1 / R) of the forward travel route, the offset D of the vehicle 1 with respect to the lane, and the yaw angle θ based on the detected lane, and sends the result to the steering assist ECU 2. To do. As a method of detecting various information amounts (curve curvature (1 / R) and own vehicle offset D / yaw angle θ) of the forward travel route based on the image, a known method can be used.

  The offset D is also referred to as a lateral shift amount or the like, and is a value indicating a lateral shift (offset) of the vehicle with respect to the travel route. The offset D is obtained based on an appropriate standard such as a center line or a center line of a traveling lane. The yaw angle θ is also called a deflection angle, and is a value indicating the direction in which the vehicle is traveling with respect to the travel route. Here, the CCD camera 8 functions as an imaging unit, and the image processing unit 9 and the driving support ECU 2 function as a detection unit. Alternatively, the image processing unit 9 may process the image to some extent and send it to the steering assist ECU 2 to calculate the curve curvature (1 / R), the offset D, and the yaw angle θ by the steering assist ECU 2. Also in this case, the image processing unit 9 and the steering assist ECU 2 function as detection means.

  A steering angle sensor 10 and a vehicle speed sensor 11 are also connected to the steering assist ECU 2. The steering angle sensor 10 outputs a signal corresponding to the steering angle of the steering wheel 3 operated by the driver. In addition to the rudder angle sensor 10, a rudder angle torque sensor or the like may be provided. The vehicle speed sensor 11 is a wheel speed sensor attached to each wheel, and generates a pulse signal at a cycle corresponding to the speed of the vehicle 1. It is also possible to obtain a vehicle speed by attaching a sensor for detecting the longitudinal acceleration of the vehicle body instead of the vehicle speed sensor 11 and integrating the output over time. The output signal of the steering angle sensor 10 and the output signal of the vehicle speed sensor 11 are respectively supplied to the steering assist ECU 2. The steering assist ECU 2 detects the steering angle based on the output signal of the steering angle sensor 10 and detects the vehicle speed based on the output signal of the vehicle speed sensor 11.

  Further, a yaw rate sensor 12 and a navigation system 13 are also connected to the steering assist ECU 2. The yaw rate sensor 12 is disposed near the center of gravity of the vehicle 1, detects the yaw rate around the center of gravity vertical axis, and sends the detection result to the steering assist ECU 2. The navigation system 13 is a device for detecting the position of the vehicle 1 using GPS or the like. The navigation system 13 also has a function of detecting a situation such as a curve curvature (1 / R) and a gradient in front of the vehicle 1. The steering assist ECU 2 uses the navigation system 13 to grasp the position of the vehicle 1 and the road situation expected to travel.

  Furthermore, an EPS-ECU 14 is also connected to the steering assist ECU 2. The EPS-ECU 14 is connected to a motor (actuator) 15 disposed in the steering gear box 5 described above. Although not shown, a ball screw groove is formed on a part of the outer peripheral surface of the rack bar 6, and a ball nut having a ball screw groove corresponding to the ball screw groove on the inner peripheral surface of the rotor of the motor 15. Is fixed. A plurality of bearing balls are accommodated between the pair of ball screw grooves, and when the motor 15 is driven, the rotor rotates to assist the axial movement of the rack bar 6, that is, the steering.

  The EPS-ECU 14 supplies a drive current to the motor 15 in accordance with a command signal from the steering assist ECU 2. The motor 15 applies a steering torque corresponding to the drive current supplied from the EPS-ECU 14 to the rack bar 6. The steering assist ECU 2 supplies a command signal to the EPS-ECU 14 according to the logic described later and drives the motor 15 to displace the rack bar 6 and steer the wheels FL and FR. The EPS-ECU 14 and the steering assist ECU 2 function as a control controller for lane keeping control.

  Further, a warning lamp 16 and a warning buzzer 17 are connected to the steering assist ECU 2. The warning lamp 16 is disposed at a position where an occupant in the passenger compartment can visually recognize, and lights up according to a command signal from the steering assist ECU 2. Further, the alarm buzzer 17 emits a sound into the vehicle interior in accordance with a command signal from the steering assist ECU 2. The steering assist ECU 2 drives the warning lamp 16 and the alarm buzzer 17 according to the logic described later, and alerts the occupant.

  Communication between the steering assist ECU 2 and the EPS-ECU 14 is performed by a CAN communication system. The steering assist ECU 2 and the EPS-ECU 14 incorporate a transmission / reception unit (communication means) for performing this CAN communication. The CAN communication system is a communication system that transmits information and data of a plurality of items converted into digital signals by a communication circuit through a pair of communication lines (twisted pair connection or the like). CAN is an abbreviation for Controller Area Network, and is serial communication conforming to the standard [ISO11898] of the International Organization for Standardization.

  The CAN communication system uses two communication lines (buses), CAN High and CAN Low, as a pair, determines the bus level based on the operating voltage, and uses this as a digital signal according to a dedicated communication protocol at a predetermined transmission rate. To communicate. The CAN communication system is a time-division multiplex bidirectional communication in which all ECUs and sensors that rehabilitate the network can use a pair of communication lines (buses) to transmit and receive data while shifting the time. System. For this reason, each ECU and sensor communicate according to a common communication protocol so that communication is performed smoothly and reliably.

  In this CAN communication protocol, CSMA / CD (carrier detection with collision detection) is used as a rule for sending data to a communication line so that all ECUs and sensors have the right to start data transmission and can share a pair of communication lines. (Multiple access) method is adopted. CSMA / CD is an abbreviation for Carrier Sense Multiple Access with Collision Detection. Each ECU always detects the state (carrier wave) of the communication line and starts data transmission only when no other data is flowing on the communication line. Communication access control. In addition, in CSMA / CD, in addition to this, when it is detected that data collides (data is simultaneously transmitted from a plurality of ECUs), data transmission is performed again after waiting for a predetermined time.

  As described above, each ECU and sensor starts data transmission in a state where no other data flows on the CAN bus, but is transmitted when data transmission is started from a plurality of ECUs and sensors at the same time. Based on the ID information included in the data itself, the transmission priority is determined, and the data not prioritized is discarded (as described above, retransmitted). Since the discarded data does not reach the receiver side, communication is interrupted. In addition, the discarded data is retransmitted, but the data that is retransmitted at this time may be retransmitted as the discarded data itself, or the data that has been recalculated and updated is retransmitted. There is also a case.

  In the latter case, on the data receiving side, the data is received as a combination of two control amounts. For example, normally, when there is a single interruption with respect to what rotates the motor once with a single command, a command to rotate the two-rotation motor including the interruption can be generated in the next command. Similarly, when there are two interruptions, a command for rotating the three-rotation motor including the two interruptions can be generated in the next instruction. As described above, in the CAN communication system, the communication interruption is not abnormal, and is a system that allows the communication interruption.

  An outline of lane keeping control (driving support control) will be described. In the lane keeping control, first, the front image of the vehicle 1 is acquired by the CCD camera 8, and the curve curvature (1 / R), the offset D, and the yaw angle θ are detected from the image. The offset D is also called a lateral deviation amount or the like, and is a value indicating a lateral deviation (offset) of the vehicle with respect to the travel route. The offset D is obtained based on an appropriate standard such as a center line or a center line of a traveling lane. The yaw angle θ is also called a deflection angle, and is a value indicating the direction in which the vehicle is traveling with respect to the travel route. These offset D and yaw angle θ are values indicating the vehicle position with respect to the travel route.

Next, based on the curve curvature (1 / R) ahead of the vehicle 1, the yaw rate ω _r necessary for causing the vehicle 1 to travel along this curve is obtained. Further, the yaw rate ω _d required for setting the current offset D of the host vehicle 1 to the target offset D ₀ is obtained. Similarly, the yaw rate ω _θ necessary for setting the current yaw angle θ of the host vehicle 1 to the target yaw angle θ ₀ is obtained. A target yaw rate ω obtained by adding these ω _r , ω _d , and ω _θ is obtained. By generating the target yaw rate ω in the vehicle, the vehicle 1 can travel along the forward curve, and the offset D and the yaw angle θ can be converged to the target value.

  Note that a relationship of G = Vω / g (g is gravitational acceleration) is established between the yaw rate ω and the lateral acceleration G. If the vehicle speed V is constant, the two correspond one-to-one. The steering torque for generating the determined yaw rate ω (or the corresponding lateral acceleration G), that is, the control amount of the motor 15 is calculated, and the motor 15 is driven based on this. As a result, the vehicle 1 travels while maintaining the lane with the lane departure being suppressed.

  Next, control for detecting an abnormality in the above-described lane keeping control will be described with reference to the flowchart of FIG. Here, it is detected whether or not it is abnormal based on the amount of change in the target steering torque for the motor 15. Normally, control is performed so that the amount of change between the previous target torque and the current target torque is less than or equal to a predetermined upper limit value. However, when the above-described communication interruption occurs, some control commands are missing, so a control command exceeding the above-described upper limit value may be received. If communication interruption occurs without determining that this is an abnormality (failure), the determination threshold value is relaxed, thereby making it possible to perform more accurate determination while avoiding unnecessary abnormality determination.

  When performing the abnormality determination based on the change in the target steering torque, first, it is determined whether or not there has been any interruption between the previous target steering torque command value and the currently received target steering torque (step 200). This determination can be made from ID information included in the command signal. If there is no interruption, it is determined whether or not | ΔT |> α using the normal determination threshold value α (step 205). Note that ΔT = (current target steering torque) − (previously stored target steering torque). If | ΔT |> α, it is determined that an abnormality has occurred in the control of the target steering torque (step 210). If | ΔT |> α is not satisfied, it is determined that the control is normal (step 215).

  On the other hand, if step 200 is denied, it is a case where a break has occurred, but it is first determined whether or not the break is only once (step 220). If there is only one interruption, the determination threshold is set to 2α which is twice that of the normal time (no interruption), and it is determined whether or not | ΔT |> 2α (step 225). If | ΔT |> 2α, it is determined that an abnormality has occurred in the control of the target steering torque (step 210). If | ΔT |> 2α is not satisfied, it is determined that the control is normal (step 215).

  In this way, the reason why the determination threshold value is changed to twice is that because the interruption has occurred once, the control amount for one time is further added, and it is not appropriate to use the normal determination threshold value α as it is. is there. Therefore, here, the determination threshold value is set to 2α for normal two times, and an abnormality determination is performed so that a more accurate determination can be performed.

  If step 220 is also denied, it is determined whether the interruption is continuous twice (step 230). If the interruption is two consecutive times, the determination threshold is set to 3α, which is three times the normal time (no interruption), and similarly, whether or not | ΔT |> 3α is determined (step 235). If | ΔT |> 3α, it is determined that an abnormality has occurred (step 210). If | ΔT |> 3α is not satisfied, it is determined that the condition is normal (step 215). The reason why the determination threshold is tripled in this way is the same as that when the determination threshold is doubled. However, the determination threshold is increased by the amount of increase in the number of interruptions. In addition, when step 230 is denied, it is a case where communication interruption has occurred three times or more continuously. In this case, it is determined that an abnormality has occurred in communication control, not steering torque control (step 240).

  The abnormality detection device of the present invention is not limited to the above-described embodiment. For example, the lane keeping control of the present embodiment has been described as one in which all of the steering torque necessary for maintaining the lane is generated by the actuator. However, as the lane keeping control, an assist system that urges the driver to steer by generating a torque equal to or less than a necessary steering torque can be considered. Further, with regard to claim 1, the predetermined function of the vehicle is not limited to the lane keeping function of the above-described embodiment.

It is a lineblock diagram of vehicles provided with one embodiment of an abnormality detection device of the present invention. It is a flowchart of the abnormality detection control by one Embodiment of the abnormality detection apparatus of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Vehicle, 2 ... Steering assistance ECU, 3 ... Steering wheel, 4 ... Steering shaft, 5 ... Steering gear box, 6 ... Rack bar, 7 ... Knuckle arm, 8 ... Camera, 9 ... Image processing part, 10 ... Steering torque DESCRIPTION OF SYMBOLS 11 ... Vehicle speed sensor, 12 ... Yaw rate sensor, 13 ... Navigation system, 14 ... EPS-ECU, 15 ... Motor, 16 ... Warning lamp, 17 ... Alarm buzzer, FL, FR ... Steering wheel.

Claims (2)

Traveling state detecting means for detecting a predetermined traveling state of the vehicle;
A controller for controlling predetermined functions of the vehicle;
Command value determining means for determining a command value for the control controller to control the predetermined function based on the vehicle running condition detected by the running condition detecting means;
Communication means for communicating the command value determined by the command value determining means from the command value determining means to the control controller by a communication method that allows communication interruption,
When the control controller detects an abnormality of the predetermined function by comparing a deviation between the previous command value received last time and the current command value received this time with a predetermined threshold value, it occurs between the previous command value and the current command value. The abnormality detection apparatus characterized by changing the predetermined threshold according to the number of interruptions. The traveling state detection means detects the position of the vehicle with respect to the traveling route based on a front image acquired by imaging the front of the vehicle,
The predetermined function is to add a steering torque to the steering mechanism based on the detected vehicle position with respect to the detected travel route, and to cause the vehicle to travel on the desired travel route,
The command value determining means calculates a steering torque to be applied to the steering mechanism;
The controller determines that the difference between the previous steering torque, which is the previous command value, and the current steering torque, which is the current command value, is greater than a predetermined threshold value. The abnormality detection apparatus according to claim 1, wherein the predetermined threshold is set to be larger as the number of interruptions between the two is larger.

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