Patent Publication Number: US-2022221858-A1

Title: Vehicle driving system

Description:
This is a continuation of U.S. patent application Ser. No. 16/255,491 filed Jan. 23, 2019, which claims priority from Japanese Patent Application No. 2018-042876 filed in Japan on Mar. 9, 2018. The disclosure of each of the prior applications is hereby incorporated by reference herein in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a driving system to be mounted to a vehicle. 
     Description of the Background Art 
     Patent document 1 (Japanese Laid-Open Patent Publication No. 2016-078530), patent document 2 (Japanese Laid-Open Patent Publication No. 2017-199299), and patent document 3 (Japanese Laid-Open Patent Publication No. H09-240502) each disclose a vehicle driving system capable of performing control of switching between automatic driving by a vehicle and manual driving by a driver. 
     In the vehicle driving system, a system on a chip (SoC) having high processing performance is mounted to an ECU for control of the automatic driving (hereinafter, referred to as “automatic driving ECU”) in order to execute automatic vehicle driving by calculating, while grasping the situation around the own vehicle, an appropriate travel route through acquisition of various information such as image information, object information, and map information from various sensors and memories. 
     The SoC has a large heat generation amount, and thus, in order to avoid hardware failure due to increase in the temperature thereof, a mechanism in which a hard IP (e.g., a circuit block having an image processing function) is shut down if a value from a temperature sensor provided in the SoC exceeds a predetermined value, is provided in advance. 
     If the hard IP is shut down when the temperature of the SoC is increased for a certain reason during automatic driving, a part of an automatic driving function being performed by the automatic driving ECU stops, and thus switching to manual driving needs to be swiftly performed. However, in a case where an operation for prompting the driver to perform the switching to the manual driving is started after a part of the automatic driving function being performed by the automatic driving ECU stops, the switching from the automatic driving by the vehicle to the manual driving by the driver may not be swiftly performed. 
     SUMMARY OF THE INVENTION 
     The present invention has been made in view of the aforementioned problem, and an object of the present invention is to provide a vehicle driving system capable of starting an operation for prompting a driver to perform switching to manual driving before a part of an automatic driving function being performed by an automatic driving ECU stops owing to increase in the temperature of the automatic driving ECU including a SoC. 
     In order to solve the aforementioned problem, one aspect of the present invention is a vehicle driving system capable of performing control of switching between automatic driving by a vehicle and manual driving by a driver, the vehicle driving system including: a temperature monitoring section configured to monitor a temperature of an automatic driving ECU which controls the automatic driving; and a control section configured to control, on the basis of the temperature of the automatic driving ECU, an operation for prompting the driver to perform the switching to the manual driving during the automatic driving. 
     With this configuration, while the automatic driving is being performed by the vehicle, the operation for prompting the driver to perform the switching to the manual driving can be performed as necessary on the basis of the change in the temperature of the automatic driving ECU. 
     In addition, in the one aspect, in a case where the temperature of the automatic driving ECU becomes equal to or greater than a predetermined first temperature threshold value that is less than a predetermined temperature upper limit within which execution of the automatic driving is allowed, the control section may execute a first operation for prompting the driver to perform the switching to the manual driving. 
     With this configuration, the operation for prompting the driver to perform the switching to the manual driving can be swiftly started before, for a certain reason, the temperature of the automatic driving ECU reaches the predetermined temperature upper limit within which execution of the automatic driving is allowed (e.g., before a part of the automatic driving function stops as a result of the automatic driving ECU being shut down). 
     In addition, in the one aspect, the control section may set the first temperature threshold value on the basis of: the temperature upper limit; a sufficient predetermined time period from a time when the first operation is executed to a time when the driver performs the switching to the manual driving; and a gradient of increase in the temperature of the automatic driving ECU. 
     By providing the predetermined time period as described above, handover of the driving operation from the vehicle to the driver can be safely performed. 
     In addition, in the one aspect, in a case where the switching to the manual driving fails to be performed even after execution of the first operation, and the temperature of the automatic driving ECU becomes equal to or greater than a predetermined second temperature threshold value that is greater than the first temperature threshold value but less than the temperature upper limit, the control section may execute a second operation for prompting the driver to perform the switching to the manual driving. 
     By providing the temperature threshold values in a stepwise manner as described above, the handover of the driving operation from the vehicle to the driver can be performed with a fail-safe measure. 
     In addition, in the one aspect, the control section may change the gradient of increase in the temperature of the automatic driving ECU on the basis of a drive state of at least one of a rear air conditioner and a blower used for cooling the automatic driving ECU. 
     Accordingly, transfer of a driving authority can be performed by estimating the change in the temperature of the automatic driving ECU in accordance with the cooling capability of a cooling mechanism. 
     In addition, another aspect of the present invention is a driving authority transfer method to be executed by a computer of a vehicle driving system capable of performing control of switching between automatic driving by a vehicle and manual driving by a driver, the driving authority transfer method including: a step of monitoring a temperature of an automatic driving ECU which controls the automatic driving; and a step of controlling, on the basis of the temperature of the automatic driving ECU, an operation for prompting the driver to perform the switching to the manual driving during the automatic driving. 
     With this method, while the automatic driving is being performed by the vehicle, the operation for prompting the driver to perform the switching to the manual driving can be performed as necessary on the basis of the change in the temperature of the automatic driving ECU. 
     With the aforementioned vehicle driving system according to the present invention, the operation for prompting the driver to perform the switching to the manual driving can be started before a part of the automatic driving function being performed by the automatic driving ECU stops owing to increase in the temperature of the automatic driving ECU including a SoC. 
     These and other objects, features, aspects, and advantageous effects of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram indicating a schematic configuration of a vehicle driving system according to an embodiment of the present invention; 
         FIG. 2  is a flowchart indicating a processing procedure of driving authority transfer control executed by an automatic driving ECU of the vehicle driving system; and 
         FIG. 3A  and  FIG. 3B  are diagrams for explaining increase, with the elapse of time, in the temperature detected by a temperature sensor. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     [Outline] 
     A vehicle driving system according to the present invention capable of performing control of switching between automatic driving by a vehicle and manual driving by a driver controls, on the basis of the temperature of an automatic driving ECU, an operation for prompting the driver to perform the switching to the manual driving during the automatic driving. Accordingly, the operation for prompting the switching from the automatic driving by the vehicle to the manual driving by the driver can be swiftly started before a part of an automatic driving function stops as a result of the automatic driving ECU being shut down owing to increase in the temperature thereof 
     [Configuration] 
       FIG. 1  is a diagram indicating a schematic configuration of a vehicle driving system  1  according to an embodiment of the present invention. The vehicle driving system  1  indicated in  FIG. 1  includes an information acquisition section  10 , an automatic driving ECU  20 , an actuator  30 , a cooling mechanism section  40 , and a request output section  50 . 
     The information acquisition section  10  is a device for acquiring various information about the situation around the vehicle and the state of a vehicle body, and is composed of, for example, a camera  11 , a millimeter wave radar  12 , a laser radar  13 , a map information database (DB)  14 , a driver monitor  15 , and a vehicle-state sensor  16 . The various information acquired by the information acquisition section  10  are outputted to the automatic driving ECU  20 . 
     The automatic driving ECU  20  is an electronic control unit for controlling automatic driving that is performed by the vehicle, and includes at least one SoC  21  and at least one MCU (Micro Controller Unit)  22 . The SoC  21  executes a predetermined calculation and a predetermined process that are related to automatic driving, on the basis of the various information acquired by the information acquisition section  10 . In the SoC  21 , a temperature sensor  23  (corresponding to “temperature monitoring section” in the claims) which monitors the temperature of the SoC  21  in order to protect a hard IP (not shown) is included. On the basis of the results of the calculation and the process executed by the SoC  21 , the MCU  22  (corresponding to “control section” in the claims) outputs a control signal for appropriately operating the actuator  30 , thereby controlling the automatic driving of the vehicle. In addition, on the basis of the temperature being monitored by the temperature sensor  23  and the drive state of the cooling mechanism section  40 , the MCU  22  controls the operation for prompting the driver to perform the switching to the manual driving during the automatic driving, via the request output section  50 . 
     The actuator  30  is a device for executing travel control of the vehicle, and is composed of, for example, an engine actuator (engine)  31 , a steering actuator (EPS)  32 , and a brake actuator (brake)  33 . The actuator  30  is operated on the basis of the control signal from the automatic driving ECU  20 . 
     The cooling mechanism section  40  is a device for cooling the automatic driving ECU  20 , and is composed of, for example, a rear air conditioner  41  and/or a blower  42 . The drive state of the cooling mechanism section  40  is outputted to the automatic driving ECU  20 . A front air conditioner may be used instead of the rear air conditioner  41 . 
     The request output section  50  is a device that outputs, for the driver, a request for a predetermined operation for transferring a driving authority from the vehicle to the driver during the automatic driving, i.e., an operation for prompting the switching from the automatic driving by the vehicle to the manual driving by the driver, on the basis of an instruction from the automatic driving ECU  20 . 
     [Control] 
     Next, the control executed by the vehicle driving system  1  according to the embodiment of the present invention will be described with further reference to  FIG. 2 ,  FIG. 3A , and  FIG. 3B .  FIG. 2  is a flowchart indicating a processing procedure of driving authority transfer control executed by the automatic driving ECU  20  of the vehicle driving system  1 .  FIG. 3A  and  FIG. 3B  are diagrams for explaining increase, with the elapse of time, in the temperature detected by the temperature sensor  23 . 
     The driving authority transfer control indicated in  FIG. 2  is started when the driving state of the vehicle is switched from the manual driving by the driver to the automatic driving by the vehicle. 
     Step S 21 : The automatic driving ECU  20  starts monitoring a temperature Temp detected by the temperature sensor  23  included in the SoC  21 . 
     Step S 22 : The automatic driving ECU  20  determines whether or not the temperature Temp detected by the temperature sensor  23  becomes equal to or greater than a predetermined first temperature threshold value T 1 . The first temperature threshold value T 1  is a reference temperature according to which determination is made as to whether or not to perform the operation for prompting the switching from the automatic driving by the vehicle to the manual driving by the driver, while a normal state is still kept. More specifically, as shown in  FIG. 3A , the first temperature threshold value T 1  is set to such a temperature that, when a predetermined time period t elapses from a time point corresponding to the first temperature threshold value T 1 , the temperature of the SoC  21  reaches a temperature Tshut at which the hard IP is shut down. The temperature Tshut at which the hard IP is shut down, corresponds to a temperature upper limit, for the automatic driving ECU  20 , within which execution of the automatic driving is allowed. The predetermined time period t is set to a sufficient time period from a time when the operation for prompting the switching to the manual driving by the driver is performed to a time when the driver performs the switching to the manual driving, and the time period t may be set to, for example, “4 seconds” as defined in an item regarding safe handover in category B 2  of the ACSF regulation. The first temperature threshold value T 1  can be determined on the basis of the gradient of increase in the temperature of the SoC  21 , the gradient being changed in accordance with the drive state of the cooling mechanism section  40 . 
     For example, as shown in  FIG. 3B , since the SoC  21  is not cooled if neither the rear air conditioner  41  nor the blower  42  is driven at all, the temperature Temp increases at a high gradient indicated by a curve C. On the other hand, if, for example, the blower  42  is driven, the SoC  21  is cooled by blown air, and thus the temperature Temp increases at a gradient indicated by a curve B gentler than the curve C. In addition, if the rear air conditioner  41  is driven, the SoC  21  is cooled by cool air, and thus the temperature Temp increases at a gradient indicated by a curve A further gentler than the curve B. Thus, the automatic driving ECU  20  can set the first temperature threshold value T 1 , according to which determination is made in step S 22 , on the basis of the temperature Tshut and the predetermined time period t in a state where an appropriate gradient of increase in the temperature is determined on the basis of the drive state of the cooling mechanism section  40 . These gradients of increase in the temperature are each desirably set to a worst value in consideration of a variation (low temperature/normal temperature/high temperature, circuit, etc.) in each of the rear air conditioner  41  and the blower  42 . 
     In a case where the temperature Temp is less than the first temperature threshold value T 1  (step S 22 ; No), the process proceeds to step S 26 . In a case where the temperature Temp is equal to or greater than the first temperature threshold value T 1  (step S 22 ; Yes), the process proceeds to step S 23 . 
     Step S 23 : The automatic driving ECU  20  determines whether or not the temperature Temp detected by the temperature sensor  23  becomes equal to or greater than a predetermined second temperature threshold value T 2 . Similarly to the aforementioned first temperature threshold value T 1 , the second temperature threshold value T 2  is a reference according to which determination is made as to whether or not to perform the operation for prompting the switching from the automatic driving by the vehicle to the manual driving by the driver, while a normal state is still kept. The second temperature threshold value T 2  is provided as a fail-safe measure for supplementing the first temperature threshold value T 1 , and is preferably set to, as shown in  FIG. 3A , a temperature (T 1 &lt;T 2 &lt;Tshut) immediately below the temperature Tshut at which the hard IP of the SoC  21  is shut down. 
     In a case where the temperature Temp is less than the second temperature threshold value T 2  (step S 23 ; No), the process proceeds to step S 24 . In a case where the temperature Temp is equal to or greater than the second temperature threshold value T 2  (step S 23 ; Yes), the process proceeds to step S 25 . 
     Step S 24 : Since there is a risk that the hard IP of the SoC  21  is shut down after the elapse of the predetermined time period t, the automatic driving ECU  20  executes a first operation for prompting the switching from the automatic driving by the vehicle to the manual driving by the driver. The first operation may be, specifically, an operation for requesting handover of the driving operation to the driver. When the first operation is executed, the process proceeds to step S 26 . 
     Step S 25 : Since there is a risk that the hard IP of the SoC  21  is shut down before long, the automatic driving ECU  20  executes a second operation for prompting the switching from the automatic driving by the vehicle to the manual driving by the driver. The second operation may be, specifically, an operation for more urgently requesting the handover of the driving operation to the driver since the switching to the manual driving has failed to be performed even after execution of the first operation. The second operation may be identical to the aforementioned first operation, or may be different therefrom. When the second operation is executed, the process proceeds to step S 26 . 
     Step S 26 : The automatic driving ECU  20  determines whether or not the driving state of the vehicle has been switched from the automatic driving by the vehicle to the manual driving by the driver. In a case where the driving state of the vehicle remains to be the automatic driving (step S 26 ; No), the process returns to step S 21 , and the series of control steps based on the temperature Temp are executed. On the other hand, in a case where the driving state of the vehicle is switched to the manual driving (step S 26 ; Yes), the driving authority transfer control is ended. 
     Operation and Effect in Present Embodiment 
     As described above, the vehicle driving system  1  according to the embodiment of the present invention includes: the temperature sensor  23  which monitors the temperature Temp of the automatic driving ECU  20  (SoC  21 ); and the MCU  22  which performs, via the request output section  50 , a request for prompting the driver to perform the switching to the manual driving during the automatic driving, on the basis of the temperature Temp. 
     With this configuration, while the automatic driving is being performed by the vehicle, if the temperature of the automatic driving ECU  20  is changing such that there is a risk that the hard IP of the SoC  21  is shut down, the operation for prompting the switching from the automatic driving by the vehicle to the manual driving by the driver can be swiftly started before a part of the automatic driving function being performed by the automatic driving ECU  20  stops. 
     In particular, in the automatic driving ECU  20  in the present embodiment, the operations (first and second operations) for prompting the driver to perform the switching to the manual driving are performed in a stepwise manner, i.e., performed in the case where the temperature Temp of the SoC  21  becomes equal to or greater than the first temperature threshold value T 1  and in the case where the temperature Temp becomes equal to or greater than the second temperature threshold value T 2  immediately before the shutdown, and the first temperature threshold value T 1  is set on the basis of the temperature upper limit, the predetermined time period t, and the gradient of increase in the temperature of the SoC  21 , whereby the handover of the driving operation from the vehicle to the driver can be safely performed with the fail-safe measure. 
     In addition, the automatic driving ECU  20  in the present embodiment changes the gradient of increase in the temperature of the SoC  21  on the basis of the drive state of at least one of the rear air conditioner  41  and the blower  42  used for cooling the automatic driving ECU  20 , and thus can perform the transfer of the driving authority by estimating the change in the temperature of the automatic driving ECU  20  in accordance with the cooling capability of the cooling mechanism section  40 . 
     In the aforementioned embodiment, the example where the temperature Temp of the SoC  21  is monitored by the temperature sensor  23  included in the SoC  21 , has been described. However, instead of using the temperature sensor  23 , the temperature Temp of the SoC  21  may be estimated from a temperature measured by an ambient temperature sensor and an actual calculation time based on internal load of the SoC  21 . 
     Furthermore, in the aforementioned embodiment, the example where the temperature sensor  23  included in the SoC  21  performs monitoring as to whether or not the temperature Temp of the SoC  21  becomes equal to or greater than the second temperature threshold value T 2 , has been described. However, the following operations may be performed: the operation situation of the hard IP is grasped, and it is determined that the hard IP has come to be in a predetermined state, so that it is assumed that the hard IP is in a state immediately before the shutdown. 
     While the present invention has been described in detail, the foregoing description is in all aspects illustrative and not restrictive. It will be understood that numerous other modifications and variations can be devised without departing from the gist of the present invention.