Abstract:
A braking system operable independent of driver input, where the braking system includes a primary brake system, a secondary brake system, a primary controller controlling fluid pressure in the primary brake system, and a secondary controller controlling fluid pressure in the secondary brake system independently of the primary controller. There is also an actuator which is part of the primary brake system, where the actuator is controlled by the primary controller. A reservoir is in fluid communication with both the primary brake system and the secondary brake system, to supply fluid to both the primary brake system and the secondary brake system. The primary controller selectively actuates the actuator to control the fluid pressure in the primary brake system independently of driver input, to provide braking capability to a fully autonomous driving vehicle.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates generally to a brake system for an autonomous driving vehicle, which eliminates unnecessary components. 
       BACKGROUND OF THE INVENTION 
       [0002]    Vehicles with autonomous driving capabilities are becoming increasingly common. Some vehicles are fully autonomous, and do not require the input of a driver. Furthermore, there are also vehicles which are used for transporting passengers or cargo, but do not have a driver, and are designed such that a driver never provides any type of input to control the vehicle. Therefore the operation of the vehicle, such as steering, turning, acceleration, and braking, are controlled by various components, such as control modules and the like. The control modules receive input from various devices, such as sensors, GPS, and the like, to determine what operations are to be performed based on certain parameters such as local speed limits, oncoming traffic signals, and the speed and location of nearby vehicles. With more vehicles being fully operational without the use of driver input, there is less and less of a need for various components which are typically used by a driver to control and maneuver the vehicle. 
         [0003]    Accordingly, there exists a need for a braking system which may be used as part of a fully autonomous vehicle, where the braking system eliminates unnecessary components which are used by a driver to control the braking system of the vehicle. 
       SUMMARY OF THE INVENTION 
       [0004]    The present invention is a braking system which does not have any components which are used by a human driver for input. 
         [0005]    In one embodiment, the present invention is a braking system operable independent of driver input, where the braking system includes a primary brake system, a secondary brake system, a primary controller controlling fluid pressure in the primary brake system, and a secondary controller controlling fluid pressure in the secondary brake system independently of the primary controller. There is also an actuator which is part of the primary brake system, where the actuator is controlled by the primary controller. A reservoir is in fluid communication with both the primary brake system and the secondary brake system, to supply fluid to both the primary brake system and the secondary brake system. The primary controller selectively actuates the actuator to control the fluid pressure in the primary brake system independently of driver input. 
         [0006]    There is also at least one ABS valve being part of the primary brake system, and at least one transition conduit placing the primary brake system in fluid communication with the secondary brake system. When there is a malfunction in the primary brake system, the secondary brake system is controlled by the secondary controller. 
         [0007]    When there is a malfunction in the primary brake system, the secondary controller is active and controls the fluid pressure in the secondary brake system, such that the secondary controller controls the fluid pressure of the secondary brake system independently of driver input. 
         [0008]    The braking system of the present invention also includes a virtual driver, where the virtual driver provides input to the primary controller to operate the primary brake system. The vehicle which incorporated the braking system according to the present invention includes several devices, such as sensors, a LIDAR system, GPS, or other devices which may be used alone or in combination to determine the environment around the vehicle. These devices function as the virtual driver. 
         [0009]    Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
           [0011]      FIG. 1  is a diagram of a braking system for an autonomous driving vehicle, according to embodiments of the present invention; 
           [0012]      FIG. 2  is a diagram of an alternate embodiment of a braking system for an autonomous driving vehicle, according to embodiments of the present invention; 
           [0013]      FIG. 3  is a diagram of another alternate embodiment of a braking system for an autonomous driving vehicle, according to embodiments of the present invention; and 
           [0014]      FIG. 4  is a diagram of another alternate embodiment of a braking system for an autonomous driving vehicle, according to embodiments of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0015]    The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
         [0016]    A diagram of a braking system according to a first embodiment of the present invention is shown in  FIG. 1 , generally at  10 . The system  10  includes a first vehicle controller  12 , and a second, or redundant, vehicle controller  14 . The first vehicle controller  12  controls a primary brake system, shown generally at  16 , and the second vehicle controller  14  is used to control a secondary brake system, generally at  18 . 
         [0017]    The primary brake system  16  includes a battery  20  which is used to supply power to an actuator, shown generally at  22 . The actuator  22  in this embodiment is a ball-screw-type of actuator  22 , which includes a motor  24 , which rotates a shaft  26  to move a piston  28  in a cylinder  30 . The actuator  22  is used to circulate fluid in a plurality of conduits. The system  10  also includes a reservoir  32  which includes two connectors  34   a ,  34   b . The reservoir  32  is divided into different sections, which are separated by partitions (not shown), where each connector  34   a , 34   b  provides fluid communication between each section of the reservoir  32  and a corresponding fluid conduit connected to each connector  34   a , 34   b . The first connector  34   a  is connected to a return conduit  36 , which is in fluid communication with cylinder  30 . Disposed in the return conduit  36  is a check valve  38  which allows for fluid in the conduit  36  to transfer to the cylinder  30  as the piston  28  is moved in a first direction towards the motor  24 . Also connected to the cylinder  30  is a main feed conduit  40 , and the main feed conduit  40  is connected to and in fluid communication with several other feed conduits  42   a , 42   b , 42   c , 42   d  which are connected to and in fluid communication with several anti-lock braking system (ABS) valves  44   a , 44   b , 44   c , 44   d , 44   e , 44   f , 44   g , 44   h . Four of the ABS valves  44   a , 44   c , 44   e , 44   g  also have pressure relief conduits  46   a , 46   b , 46   c , 46   d , and a check valve  48   a , 48   b , 48   c , 48   d  located in a corresponding conduit  46   a , 46   b , 46   c , 46   d . The system  10  also includes four braking units  50   a , 50   b , 50   c , 50   d , and there are two ABS valves  44   a , 44   b , 44   c , 44   d , 44   e , 44   f , 44   g , 44   h  responsible for providing an anti-lock braking function for each braking unit  50   a , 50   b , 50   c , 50   d . More specifically, the first two ABS valves  44   a , 44   b  provide the anti-lock braking function for the first braking unit  50   a , the third and fourth ABS valves  44   c , 44   d  provide the anti-lock braking function for the second braking unit  50   b , the fifth and sixth ABS valves  44   e , 44   f  provide the anti-lock braking function for the third braking unit  50   c , and the seventh and eighth ABS valves  44   g , 44   h  provide the anti-lock braking function for the fourth braking unit  50   d . The first two ABS valves  44   a , 44   b  are connected to and in fluid communication with the first braking unit through a first final conduit  52   a , and the fifth and sixth ABS valves  44   e , 44   f  are connected to and in fluid communication with the third braking unit  50   c  through a second final conduit  52   b , as shown in  FIG. 1 . 
         [0018]    The third and fourth ABS valves  44   c , 44   d  and the seventh and eighth ABS valve  44   g , 44   h  are connected to and in fluid communication with the secondary brake system  10  through corresponding transition conduits  54   a , 54   b . More specifically, the first transition conduit  54   a  is connected to and in fluid communication with a first master cylinder cut valve  56   a , and the second transition conduit  54   b  is connected to and in fluid communication with a second master cylinder cut valve  56   b . Each of the master cylinder cut valves  56   a , 56   b  have corresponding pressure relief conduits  56   c , 56   d , and corresponding check valves  60   a , 60   b . The master cylinder cut valves  56   a , 56   b  are part of the secondary brake system  18 . 
         [0019]    In addition to the return conduit  36 , also connected to and in fluid communication with the reservoir  32  is an upstream feed conduit  58 , the upstream feed conduit  58  branches into two separate secondary feed conduits  58   a , 58   b . One of the secondary feed conduits  58   a  is connected to and in fluid communication with several sub-conduits  64   a , 64   b , 64   c , 64   d , where the first sub-conduit  64   a  is in fluid communication with the second ABS valve  44   b , the second sub-conduit  64   b  is in fluid communication with the fourth ABS valve  44   d , the third sub-conduit  64   c  is in fluid communication with the sixth ABS valve  44   f , and the fourth sub-conduit  64   d  is in fluid communication with the eighth ABS valve  44   h.    
         [0020]    The other secondary feed conduit  58   b  is in fluid communication with the secondary brake system  18 , and more specifically splits into two additional conduits  62   a , 62   b , which are connected to and in fluid communication with corresponding reservoirs  66   a , 66   b . The secondary brake system  18  also includes two low-pressure feed valves  68   a , 68   b , which are in fluid communication with the corresponding reservoirs  66   a , 66   b  through conduits  70   a , 70   b  as shown in  FIG. 1 . Each of the low-pressure feed valves  68   a , 68   b  is connected to and in fluid communication with a pump  72   a , 72   b , and both pumps  72   a , 72   b  are driven by a motor  74 . 
         [0021]    The secondary brake system  18  also includes excess pressure relief valves  76   a , 76   b  which are in fluid communication with the reservoirs  66   a , 66   b  through pressure relief conduits  78   a , 78   b  as shown in  FIG. 1 . There are also two corresponding downstream pressure relief conduits  80   a , 80   b  which are connected to the excess pressure relief valves  76   a , 76   b  as shown in  FIG. 1 , and the conduits  80   a , 80   b  are also connected to and in fluid communication with corresponding cut-valve downstream conduits  82   a , 82   b . Each of the cut-valve downstream conduits  82   a , 82   b  splits, such that the first cut-valve downstream conduit  82   a  is in fluid communication with the second braking unit  50   b  and the first pump  72   a , and the second cut-valve downstream conduit  82   b  is in fluid communication with the fourth braking unit  50   d  and the second pump  72   b.    
         [0022]    There are also several sensors used to monitor various operating parameters at different locations in each system  16 , 18 . In this embodiment shown in  FIG. 1 , there is a position sensor  84  and a temperature sensor  86  for monitoring the position and the temperature of the motor  24 . There are also several pressure sensors, one pressure sensor  88  connected to one of the feed conduits  42   a , another pressure sensor  90  connected to one of the transition conduits  54   b , and two pressure sensors  92 , 94  connected to each corresponding pump  72   a , 72   b . There is also a brake fluid level sensor  96  which is connected to the reservoir  32 , which is used to detecting the level of fluid in the reservoir  32 . 
         [0023]    Additionally, there is also a first parking brake unit  98   a  which is attached to the first, or rear left braking unit  50   a , and a second parking brake unit  98   b  which is attached to the third, or rear right braking unit  50   c . The parking brake units  98   a , 98   b  are controlled by a secondary controller  100 , which is part of the secondary brake system  18 . The secondary controller  100  is in electrical communication with the second vehicle controller  14 , and both the secondary controller  100  and the second vehicle controller  14  are powered by a battery  102 . 
         [0024]    The primary braking system  16  also includes a primary controller  104  which is in electrical communication with the first vehicle controller  12 , and both the primary controller  104  and first vehicle controller  12  are powered by the battery  20 . 
         [0025]    In operation, the first vehicle controller  12  receives input to determine when and how the primary brake system  16  should be operated. This input may be received from various devices, such as sensors, a LIDAR system, GPS, or other devices which may be used alone or in combination to determine the environment around the vehicle. These devices may function as a virtual driver  108 , which, based on the surrounding environment (such as the location and speed of nearby vehicles, local traffic ordinances, speed limits, nearby pedestrians, and nearby signs and traffic signals, and weather conditions) send signals providing input the vehicle in a similar manner to a human driver, to command the controllers  12 , 14  to operate the primary brake system  16 , or the secondary brake system  18 , respectively. If it is determined one or more of the braking units  50   a , 50   b , 50   c , 50   d  needs to be activated, the first vehicle controller  12  sends signals to the primary controller  104  to activate the motor  24 . The motor  24  rotates the shaft  26  to move the piston  28  in the first direction, towards the motor  24 , or a second direction, away from the motor  24 . When the piston  28  is moved in the first direction, fluid is drawn into the cylinder  30  from the return conduit  36  and through the check valve  38 . 
         [0026]    When the piston  28  is moved in the second direction, fluid is forced into the main feed conduit  40 , and is then distributed throughout the other various conduits  42   a , 42   b , 42   c , 42   d  mentioned above, depending on the configuration of the ABS valves  44   a , 44   b , 44   c , 44   d , 44   e , 44   f , 44   g , 44   h  of the primary brake system  16 . A portion of the fluid flows through the final conduits  52   a , 52   b  such that the rear brake units  50   a , 50   c  are actuated, and another portion of the fluid flows through the transition conduits  54   a , 54   b  into the secondary brake system  18 . When the primary brake system  16  is operating, the secondary brake system  18  is inactive. When the secondary brake system  18  is inactive, the fluid flowing through the transition conduits  54   a , 54   b  passes through the master cylinder cut valves  56   a , 56   b , and flows through the cut-valve downstream conduits  82   a , 82   b  and to the front right brake unit  50   b  and the front left brake unit  50   d  to generate a braking force. The piston  28  is moved in either the first direction to decrease braking force or the second direction to increase braking force. 
         [0027]    If there is a failure anywhere in the primary brake system  16 , the secondary brake system  18  is activated. The failure in the primary brake system  16  may be a result of failure of the actuator  22 , a failure in the first vehicle controller  12 , the primary controller  104 , or some other component in the primary brake system  16 . The second vehicle controller  14  receives the input, and responds by sending commands to the secondary controller  100 . When the secondary brake system  18  is activated, the secondary controller  100  configures the master cylinder cut valves  56   a , 56   b  to be in a closed position, preventing fluid from passing back into the transition conduits  54   a , 54   b . Each of the reservoirs  66   a , 66   b  receive fluid from the reservoir  32 , and the secondary controller  100  controls the motor  74 , to thereby control each of the pumps  72   a , 72   b . Each of the low-pressure feed valves  68   a , 68   b  controls the flow of fluid from the corresponding reservoirs  66   a , 66   b  to each pump  72   a , 72   b , and the excess pressure relief valves  76   a , 76   b  relieve pressure in the cut-valve downstream conduits  82   a , 82   b  to keep the pressure in the cut-valve downstream conduits  82   a , 82   b  below a desired level. 
         [0028]    Another embodiment of the invention is shown in  FIG. 2 , with like numbers referring to like elements. In this embodiment, the upstream feed conduit  58  is only in fluid communication with the secondary feed conduit  58   b , and the other secondary feed conduit  58   a  is connected to and in fluid communication with the return conduit  36 . 
         [0029]    Another embodiment of the invention is shown in  FIG. 3 , with like numbers referring to like elements. In this embodiment, the upstream feed conduit  58  is still connected both the secondary feed conduits  58   a , 58   b , but the upstream feed conduit  58  is connected to the first connector  34   a , and the return conduit  36  is connected to the second connector  34   b.    
         [0030]    Yet another embodiment is shown in  FIG. 4 , with like numbers referring to like elements. In this embodiment, the upstream feed conduit  58  is connected to the first connector  34   b , and the upstream feed conduit  58  is connected to and in fluid communication with the secondary feed conduit  58   a  and the return conduit  36 . The other secondary feed conduit  58   b  is connected to the first connector  34   a.    
         [0031]    The embodiments shown in  FIGS. 2-4  provide the same functionality as the system  10  shown in  FIG. 1 , but demonstrate there are other possible configurations for the upstream feed conduit  58 , secondary feed conduits  58   a , 58   b , and return conduit  36 . Although the variations in  FIGS. 2-4  are shown, it is within the scope of the invention that other configurations may be used. 
         [0032]    The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.