Abnormality determination apparatus for vehicle

Abstract

To provide an abnormality determination apparatus for a vehicle that can determine abnormalities in left and right travel drive sources with high accuracy at low cost.SOLUTION: An abnormality determination apparatus for a vehicle 1, which is capable of independently driving left and right wheels, comprises a right front wheel drive motor 3 that drives a right front wheel 2, and a left front wheel drive motor 5 that drives a left front wheel 4. The apparatus further comprises a turning speed calculation unit 30 that estimates a turning speed of the vehicle based at least on commanded driving torque of the right front wheel drive motor 3 and commanded driving torque of the left front wheel drive motor 5, a turning speed sensor 27 that detects an actual turning speed of the vehicle, and a traveling abnormality determination unit 20 that determines abnormalities in a right front wheel driving system and a left front wheel driving system on the basis of a difference between an estimation value of the turning speed and the actual turning speed of the vehicle 1.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a technology for determining an abnormality in a vehicle driving system. [Background technology]

[0002] Independently driven vehicles, such as electric vehicles, have been developed, in which the left and right wheels are driven by independent motors. In such vehicles, if there is a difference in the drive torque output of the left and right motors due to, for example, motor failure, deterioration, or individual performance variations, this can lead to a decrease in straight-line driving performance. Patent document 1 proposes a control device that, in a vehicle with independent drive for left and right wheels, when the drive torque of one of the left or right wheels decreases due to, for example, a failure in the left or right driving source, suppresses the drive torque of the other drive wheel, thereby suppressing unintended turning of the vehicle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-116069 A Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, when a torque drop detection device detects a drop in the actual torque of either the left or right motor, the device controls the other motor so as to set an upper limit for the motor torque based on the turning direction of the vehicle. The torque drop detection device calculates the required torque based on the vehicle speed, brake fluid pressure, and accelerator opening, and compares it with the actual torque detected by the torque sensor to determine the torque drop. However, in Patent Document 1, new torque sensors must be provided to detect the actual torque of the left and right motors, which poses a problem of increased costs.

[0005] The present invention has been made in consideration of these problems, and its purpose is to provide a vehicle abnormality determination device that can accurately determine abnormalities in the left and right driving sources at low cost at all times while the vehicle is traveling. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the abnormality judgment device for a vehicle of the present invention is an abnormality judgment device for a vehicle equipped with a right wheel drive device that drives the right wheels of the vehicle and a left wheel drive device that drives the left wheels of the vehicle, and is characterized by comprising: a turning speed estimation unit that estimates the turning speed of the vehicle based on at least the indicated driving torque of the right wheel drive device and the indicated driving torque of the left wheel drive device; an actual turning speed detection unit that detects the actual turning speed of the vehicle; and a judgment control unit that makes an abnormality judgment for the right wheel drive device and the left wheel drive device based on the difference between the estimated value of the turning speed of the vehicle and the actual turning speed. [Effects of the Invention]

[0007] The vehicle abnormality detection device of the present invention performs abnormality detection based on the difference between the estimated turning speed and the actual turning speed, making it easy to determine whether either the left or right driving drive system is abnormal at all times while the vehicle is traveling. Furthermore, by performing abnormality detection based on the turning speed, it is possible to comprehensively determine abnormalities in both the left and right drive systems, thereby improving the accuracy of abnormality detection. Furthermore, since abnormality detection in the driving drive systems is possible without the need to detect left and right drive torques, it is possible to perform abnormality detection at low cost. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic configuration diagram of a driving system of a vehicle that employs an abnormality determination device according to an embodiment of the present invention; [Figure 2] 1 is a configuration diagram of an abnormality determination device according to an embodiment of the present invention; [Figure 3] 4 is a flowchart showing a control procedure for abnormality determination control executed in a driving abnormality determination unit according to the present embodiment. [Figure 4]10 is a map showing the relationship between the turning speed difference and the turning speed difference increase rate and the determination result in the abnormality determination control of the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a vehicle abnormality determination device embodying the present invention will now be described. Fig. 1 is a schematic diagram of a vehicle drivetrain that employs an abnormality determination device according to the present embodiment, and Fig. 2 is a diagram of the abnormality determination device according to the present embodiment. The abnormality determination device of the present invention is mounted on a vehicle in which the left and right wheels are driven independently. As shown in FIG. 1, the vehicle 1 employing the abnormality determination device 15 of this embodiment is a front-wheel drive electric vehicle in which the right front wheel 2 is driven by a right front wheel drive motor 3 (right wheel drive device) and the left front wheel 4 is driven by a left front wheel drive motor 5 (left wheel drive device).

[0010] The vehicle 1 is provided with a storage battery 6 as a power supply source for the right front wheel drive motor 3 and the left front wheel drive motor 5. The right front wheel drive motor 3 is supplied with power from the storage battery 6 via a right front wheel drive motor inverter 7. The left front wheel drive motor 5 is supplied with power from the storage battery 6 via a left front wheel drive motor inverter 8.

[0011] The right front wheel drive motor inverter 7 and the left front wheel drive motor inverter 8 receive control signals from the main control unit 10 and control the power supply to the left and right front wheel drive motors 3, 5. The main control unit 10 is a control unit that controls the driving of the vehicle 1, and receives input such as accelerator operation amount, calculates the driving force of the right front wheel drive motor 3 (right command driving force) and the driving force of the left front wheel drive motor 5 (left command driving force), and controls the operation of the right front wheel drive motor 3 via a right front wheel drive motor inverter 7 and the left front wheel drive motor 5 via a left front wheel drive motor inverter 8. The main control unit 10 also includes a driving abnormality determination section 20 (determination control section) that determines abnormalities in the driving system of the left and right front wheel drive motors 3, 5, etc.

[0012] The main control unit 10 is configured to include an output device, a memory device (ROM, RAM, non-volatile RAM, etc.), a central processing unit (CPU), etc. The driving abnormality determination unit 20 receives as input the vehicle speed, the vehicle steering angle, the left command drive torque, the right command drive torque, and the actual turning speed. The vehicle speed is input from a vehicle speed sensor 25 provided in the vehicle 1. The steering angle is input from a steering angle sensor 26 provided in the vehicle 1. The actual turning speed is input from a turning speed sensor 27 (actual turning speed detection unit) provided in the vehicle.

[0013] The left command drive torque is the output command torque of the left front wheel drive motor 5, and the right command drive torque is the output command torque of the right front wheel drive motor 3. The left command drive torque and the right command drive torque are calculated in the main control unit 10 based on the accelerator operation amount, steering angle, etc. The abnormal driving determination unit 20 includes a turning speed calculation unit 30 (turning speed estimation unit) and a comparison unit 31.

[0014] The turning speed calculation unit 30 estimates the turning speed of the vehicle 1 (calculates the estimated turning speed ωs) based on the vehicle speed, steering angle, left command drive torque, and right command drive torque. The comparison unit 31 compares the estimated turning speed ωs calculated by the turning speed calculation unit 30 with the actual measurement value of the turning speed (actual turning speed ωa) input from the turning speed sensor 27 to determine whether the traveling drive system of the vehicle 1 is normal or abnormal, and outputs the determination result to the traveling drive suppression control unit 35 (travel suppression control unit) and the alarm device 36 (alarm unit).

[0015] The notification device 36 is a device that notifies the driver of the vehicle 1, and is, for example, a device that outputs warning sounds or voices, a display device such as an indicator near the driver's seat, or a vibration applying device provided on the brake pedal or driver's seat. The running drive suppression control unit 35 is provided in the main control unit 10, for example, and reduces the command drive torque of the right front wheel drive motor 3 and the left front wheel drive motor 5.

[0016] The driving abnormality determination unit 20 performs abnormality determination control to determine whether the right front wheel drive system (right front wheel drive motor 3 and right front wheel drive motor inverter 7) and the left front wheel drive system (left front wheel drive motor 5 and left front wheel drive motor inverter 8) are normal or abnormal. Fig. 3 is a flowchart showing the control procedure of abnormality determination control executed in the traveling abnormality determination unit 20. Fig. 4 is a map showing the relationship between the turning speed difference Δω and the turning speed difference increase rate Rω and the determination result in the abnormality determination control.

[0017] The abnormality determination control is repeatedly performed at predetermined time intervals (for example, every few msec) when the vehicle power supply is ON or while the vehicle is running. First, in step S10, the turning speed calculation unit 30 inputs the vehicle speed, steering angle, left command drive torque, and right command drive torque to calculate the turning speed (estimated turning speed ωs) of the vehicle 1. Then, the process proceeds to step S20. Note that in this step, the left actual drive torque and right actual drive torque are not detected, but rather the calculation is performed using values ​​detected by sensors provided in many vehicles 1 and values ​​that can be easily obtained from the main control unit 10, etc., such as the left command drive torque and right command drive torque.

[0018] The estimated turning speed ωs can be calculated by a known calculation method, one example of which is outlined below. The estimated turning speed ωs is calculated, for example, by the following steps 1) to 4). In step 1), the angular difference α between the vehicle traveling direction and the direction of the rear wheels, and the angular difference β between the vehicle traveling direction and the direction of the front wheels are calculated. The direction of the rear wheels is fixed to the vehicle body, and the direction of the front wheels is calculated from the steering angle. The vehicle traveling direction is calculated from the turning speed (yaw rate) from the turning speed sensor 27 and the vehicle speed.

[0019] In step 2), the lateral force of the wheel is calculated from the angle differences α and β and the cornering power, which is a characteristic value of the wheel (tire). In step 3), the resultant vector Ffr of the driving force of the right front wheel and the lateral force of the right front wheel, and the resultant vector Ffl of the driving force of the left front wheel and the lateral force of the right front wheel are calculated. Note that the driving forces of the front wheels are calculated using the left command driving torque and the right command driving torque.

[0020] In step 4), the estimated turning speed increase rate ω' (= Rω) and the estimated turning speed ωs are calculated from the resultant vector calculated in step 3. The estimated turning speed increase rate ω' can be calculated using the following equations 1 and 2, and the estimated turning speed ωs can be found by integrating the estimated turning speed increase rate ω'.

[0021]

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[0022] In the above equations 1 and 2, Vfr is the vector between the right front wheel contact patch and the vehicle's center of gravity, Vfl is the vector between the left front wheel contact patch and the vehicle's center of gravity, Vrr is the vector between the right rear wheel contact patch and the vehicle's center of gravity, and Vrl is the vector between the left rear wheel contact patch and the vehicle's center of gravity. The turning force around the center of gravity is calculated by calculating the cross product of the force vectors of each wheel and adding them up. Also, Frr is the lateral force of the right rear wheel, and Frl is the lateral force of the left rear wheel, and these are calculated from the cornering power, which is a tire characteristic value. M is the moment of inertia.

[0023] In step S20, the actual turning speed ωa is input from the turning speed sensor 27, and the comparison unit 31 calculates the turning speed difference Δω (=ωa−ωs), which is the difference between the actual turning speed ωa and the estimated turning speed ωs calculated in step S10. Then, the process proceeds to step S30. In step S30, the turning speed difference increase rate Rω is obtained from the transition of the turning speed difference Δω calculated in step S20, and the process then proceeds to step S40.

[0024] In step S40, it is determined whether the turning speed difference increase rate Rω calculated in step S30 is greater than an increase rate threshold R1 (a predetermined value). The increase rate threshold R1 may be set appropriately to a value that, for example, does not normally occur when the vehicle 1 is turning, as the increase rate of the speed difference between the right front wheel and the left front wheel. If the turning speed difference increase rate Rω is greater than the increase rate threshold R1, the process proceeds to step S90. If the turning speed difference increase rate Rω is equal to or less than the increase rate threshold R1, the process proceeds to step S50.

[0025] In step S50, a threshold value for determining the turning speed difference Δω (speed difference threshold value) is set to a first threshold value ω1. The first threshold value ω1 may be appropriately set to a value close to the upper limit of the value at which the absolute value of the turning speed difference Δω can be traveled by correcting the command drive torque in step S80, which will be described later. Then, the process proceeds to step S60. In step S60, it is determined whether the absolute value of the turning speed difference Δω calculated in step S20 is greater than the first threshold value ω1 set in step S50. If the absolute value of the turning speed difference Δω is greater than the first threshold value ω1, the process proceeds to step S70. If the absolute value of the turning speed difference Δω is equal to or less than the first threshold value ω1, the process proceeds to step S80.

[0026] In step S70, the alarm device 36 issues an output abnormality in the left and right drive trains. Furthermore, the running drive suppression control unit 35 reduces the left command drive torque of the left front wheel drive motor 5 and the right command drive torque of the right front wheel drive motor 3 to suppress the running drive to an extent that allows evacuation running. Then, the routine returns. In step S80, it is determined that the left and right drive trains are normal. In this step, if the turning speed difference Δω is other than 0, it is determined that the turning speed difference Δω is caused by deterioration of the drive train, and the left and right command drive torques should be corrected so that the turning speed difference Δω becomes 0. In this case, there is no need for a particular notification from the notification device 36. Then, this routine returns.

[0027] In step S90, a threshold value for determining the turning speed difference Δω (speed difference threshold value) is set to a second threshold value ω2. The second threshold value ω2 may be set appropriately to a value greater than the first threshold value ω1. Then, the process proceeds to step S100. In step S100, it is determined whether the absolute value of the turning speed difference Δω calculated in step S20 is greater than the second threshold value ω2 set in step S90. If the absolute value of the turning speed difference Δω is greater than the second threshold value ω2, the process proceeds to step S110. If the absolute value of the turning speed difference Δω is equal to or less than the second threshold value ω2, the process proceeds to step S120.

[0028] In step S110, the alarm device 36 issues an output abnormality in the left and right drive trains. Furthermore, the running drive suppression control unit 35 reduces the left command drive torque of the left front wheel drive motor 5 and the right command drive torque of the right front wheel drive motor 3 to suppress the running drive to an extent that allows evacuation running. Then, the routine returns. In step S120, the alarm device 36 notifies the driver that there is an output abnormality in the left and right drive trains. Note that in this step, the driving force is not suppressed as in step S110. Then, this routine is returned.

[0029] As described above, in the vehicle 1 of this embodiment, the right front wheel 2 and the left front wheel 4 are driven independently by different motors. Therefore, if an abnormality occurs in the drive system such that the outputs of the left and right drive systems differ due to individual differences between the right front wheel drive motor 3 and the left front wheel drive motor 5, aging deterioration, or the like, straight-line running performance may be degraded even if the left command drive torque and the right command drive force are made the same to run straight. Furthermore, if there is such a difference in the outputs of the left and right drive systems when a straight-line running command is issued, cornering performance will also be degraded, such that the left and right turning performance will differ.

[0030] In this embodiment, the turning speed is estimated during turning, and abnormality determination is performed based on the difference between the estimated turning speed ωs and the actual turning speed ωa (turning speed difference Δω), so it is possible to easily determine if either the left or right driving drive system is abnormal at all times while the vehicle is traveling. Note that even when traveling straight, the estimated turning speed ωs can be set to 0 for determination. By determining an abnormality based on the turning speed of the vehicle 1 while driving, it is possible to determine an abnormality in the driving and driving system of the entire vehicle, including not only the right front wheel drive motor 3 and the left front wheel drive motor 5, but also the reducers between the left and right front wheel drive motors 3, 5 and the front wheels 2, 4, the inverters 7, 8 that control the left and right front wheel drive motors 3, 5, and even the body, brake equipment, and tires, thereby improving the accuracy and effectiveness of abnormality determination.

[0031] Furthermore, while driving, the turning speed can be easily estimated based on information from sensors and devices mounted on many vehicles, such as vehicle speed and steering angle, and information that can be easily obtained from the main control unit 10 for driving control, such as left command drive torque and right command drive torque. Since abnormality determination is performed by comparing the actual turning speed ωa, which is the detection value of the turning speed sensor 27, with the estimated turning speed ωs, there is no need to actually measure the right drive torque or left drive torque, and abnormality determination can be performed easily and at low cost for the left and right driving systems.

[0032] In this embodiment, abnormality determination is made based on the turning speed difference Δω between the estimated turning speed ωs calculated in the turning speed calculation unit 30 and the actual turning speed ωa, and the rate of increase / decrease of the turning speed difference Δω (turning speed difference increase rate Rω), making it possible to make more accurate abnormality determination and improving the effectiveness of abnormality determination. As shown in FIG. 4, a threshold value for determining the turning speed difference Δω is set to a first threshold value ω1 or a second threshold value ω2 based on the turning speed difference increase rate Rω, and if the actual turning speed ωa is greater than the threshold value, an abnormality is determined, an alarm is issued by the alarm device 36, and driving suppression control is performed to suppress the command drive torque of the left and right front wheel drive motors 3, 5. Therefore, in a situation where the turning speed difference Δω is large, the driver or the like is made aware of the situation, and the driving speed is automatically reduced, thereby improving safety.

[0033] Furthermore, if the turning speed difference increase rate Rω is greater than the increase rate threshold R1 and the turning speed difference Δω is equal to or less than the second threshold ω2, the driving suppression is not performed and an alarm is issued by the alarm device 36. This makes it possible to prevent a decrease in driving performance due to driving suppression, while making the driver or the like aware that the turning speed difference Δω may increase, and to encourage the driver or the like to suppress driving at their own discretion, for example by suppressing operation of the accelerator.

[0034] Furthermore, because the threshold value for determining the turning speed difference Δω is set to a different value, either the first threshold value ω1 or the second threshold value ω2, based on the turning speed difference increase rate Rω, the timing for starting the driving suppression of the vehicle can be set appropriately. For example, the second threshold value ω2, which is set when the turning speed difference increase rate Rω is greater than the increase rate threshold R1, is a value greater than the first threshold value ω1, which is set when the turning speed difference increase rate Rω is equal to or less than the increase rate threshold R1. However, when the turning speed difference increase rate Rω is greater than the increase rate threshold R1, the alarm device 36 issues an alarm regardless of the turning speed difference Δω. This reduces the opportunities for driving suppression while ensuring safety, and suppresses deterioration of driving performance.

[0035] Furthermore, if the turning speed difference increase rate Rω is equal to or less than the increase rate threshold R1 and the turning speed difference Δω is equal to or less than the first threshold ω1, it is determined to be normal, but if the turning speed difference Δω is not 0, it is deemed that the driving system has deteriorated, and the left command drive torque and right command drive torque are corrected so that the turning speed difference Δω becomes 0 without issuing an alarm via the alarm device 36. In this way, if the driving system is deteriorated, the deterioration in driving performance due to the deterioration can be resolved without causing any inconvenience to the driver, etc.

[0036] The present invention is not limited to the above-described embodiment, and can be modified within the scope of the invention. For example, in the above embodiment, the abnormality determination is made based on the rate of increase or decrease of the turning speed difference Δω between the estimated turning speed ωs and the actual turning speed ωa (turning speed difference increase rate Rω), but the abnormality determination may also be made based on the turning speed difference Δω. For example, it may be determined that an abnormality exists when the turning speed difference Δω is equal to or greater than an appropriately set threshold value. Furthermore, the abnormality determination based on the turning speed difference increase rate Rω and the abnormality determination based on the turning speed difference Δω may be made separately, and an abnormality may be determined if either is determined to be abnormal.

[0037] The estimated turning speed ωs may be calculated by a method other than that described in the above embodiment. However, from the viewpoint of cost reduction, it is preferable to use information on devices provided in the vehicle 1 for other purposes, information on the left and right command drive torques, etc. In this embodiment, the present invention is applied to a vehicle in which the left and right front wheels are driven by electric motors, but it may also be applied to a vehicle in which the rear wheels are driven by electric motors, or a four-wheel drive vehicle in which at least the front and rear wheels are driven independently.The present invention may also be applied to a vehicle in which the left and right wheels are driven independently by means other than electric motors. [Explanation of symbols]

[0038] 1 vehicle 2 Right front wheel (right wheel) 4 Front left wheel (left wheel) 3 Right front wheel drive motor (right wheel drive unit) 5 Left front wheel drive motor (left wheel drive unit) 15 Abnormality determination device 20. Driving abnormality determination unit (determination control unit) 27 Swing speed sensor (actual swing speed detection unit) 30 Turning speed calculation unit (turning speed estimation unit) 35 Travel drive suppression control unit 36 Alarm device (alarm unit)

Claims

1. An abnormality determination device for a vehicle including a right wheel drive device that drives a right wheel of the vehicle and a left wheel drive device that drives a left wheel of the vehicle, a turning speed estimation unit that estimates a turning speed of the vehicle based on at least the command drive torque of the right wheel drive unit and the command drive torque of the left wheel drive unit; an actual turning speed detection unit that detects an actual turning speed of the vehicle; a determination control unit that determines whether the right wheel drive device and the left wheel drive device are abnormal based on a difference between the estimated value of the turning speed of the vehicle and the actual turning speed. A vehicle abnormality determination device characterized by:

2. The determination control unit performs abnormality determination based on a speed difference between the estimated value of the turning speed estimated by the turning speed estimation unit and the actual turning speed, and a rate of increase or decrease of the speed difference.

2. The vehicle abnormality determination device according to claim 1.

3. a travel suppression control unit that suppresses travel of the vehicle when an abnormality is determined by the determination control unit; 3. The vehicle abnormality determination device according to claim 2.

4. The determination control unit A threshold value for the speed difference is set based on an increase rate of the speed difference, and when the speed difference is greater than the threshold value, the running suppression control unit suppresses the indicated drive torque for the right wheel drive unit and the indicated drive torque for the left wheel drive unit.

4. The vehicle abnormality determination device according to claim 3.

5. a notification unit that notifies that the right wheel drive device and the left wheel drive device are abnormal; The determination control unit When the speed difference is greater than the threshold value, the notification unit issues a notification, and the running suppression control unit suppresses the indicated drive torque of the right wheel drive unit and the indicated drive torque of the left wheel drive unit.

5. The vehicle abnormality determination device according to claim 4.

6. The determination control unit When the rate of increase of the speed difference is greater than a predetermined value and the speed difference is equal to or less than the threshold value, the travel suppression control unit does not suppress the command drive torque, and the notification unit issues a notification.

6. The vehicle abnormality determination device according to claim 5.

7. The determination control unit When the rate of increase of the speed difference is equal to or less than the predetermined value and the speed difference is equal to or less than the threshold value, the notification unit does not issue a notification and the running suppression control unit does not suppress the command drive torque, and the command drive torques of the right wheel drive device and the left wheel drive device are corrected.

6. The vehicle abnormality determination device according to claim 5.

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