Vehicle braking systems and methods

Techniques for braking an autonomous vehicle include providing a pressurized fluid stream from a plurality of pressurized fluid sources to a plurality of pressure-controlled electronic braking assemblies; providing the pressurized fluid stream from a pressurized fluid control output of a first pressure-controlled electronic braking assembly directly to a pressurized fluid control input of a second pressure-controlled electronic braking assembly; providing the pressurized fluid stream from the second pressure-controlled electronic braking assembly to at least one vehicle brake set; providing sensor output data from one or more vehicle sensors to a plurality of electronic control units; and based at least in part on the sensor output data, controlling at least one of the first or second pressure-controlled electronic braking assemblies to adjust a pressure of the pressurized fluid stream from at least one of the first or second pressure-controlled electronic braking assemblies to the vehicle brake set.

BACKGROUND

This specification relates to vehicle braking systems and methods.

SUMMARY

This disclosure describes vehicle braking systems and methods. In some implementations, the vehicle braking systems and methods are applied to autonomous vehicles including self-driving cars, boats, or aircraft, which use a variety of on-board sensors and computer systems to detect nearby objects and use such detections to make control and navigation decisions. In some implementations, the vehicle braking systems and methods of the present disclosure are applied to commercial freight vehicles, such as Class 8 trucking vehicles, which may or may not be autonomous vehicles. In some aspects, vehicle braking systems and methods according to the present disclosure may include a redundant braking assembly.

In an example implementation, an autonomous vehicle braking system includes a plurality of pressure-controlled electronic braking assemblies and a plurality of electronic control units. Each pressure-controlled electronic braking assembly is fluidly coupled to at least one of a plurality of pressurized fluid sources and to at least one vehicle brake set of a plurality of vehicle brake sets of the autonomous vehicle. A pressurized fluid control output of a first pressure-controlled electronic braking assembly of the plurality of pressure-controlled electronic braking assemblies is directly connected to a pressurized fluid control input of a second pressure-controlled electronic braking assembly of the plurality of pressure-controlled electronic braking assemblies. Each of the plurality of electronic control units is communicably coupled to the first and second pressure-controlled electronic braking assemblies and one or more vehicle sensors. Each of the plurality of electronic control units is configured to command at least one of the first or second pressure-controlled electronic braking assemblies to adjust a pressure of at least one pressurized fluid stream from the at least one of the first or second pressure-controlled electronic braking assemblies to the at least one vehicle brake set based at least in part on sensor output from the one or more vehicle sensors.

In an aspect combinable with the example implementation, the plurality of pressurized fluid sources include a first pressurized fluid source connected to the first and second pressure-controlled electronic braking assemblies and a second pressurized fluid source connected to the first and second pressure-controlled electronic braking assemblies.

In another aspect combinable any one of the previous aspects, the pressurized fluid control output of the first pressure-controlled electronic braking assembly includes a first pressurized fluid control output of the first pressure-controlled electronic braking assembly and the pressurized fluid control input of the second pressure-controlled electronic braking assembly includes a first pressurized fluid control input of the second pressure-controlled electronic braking assembly.

Another aspect combinable any one of the previous aspects further includes a second pressurized fluid control output of the first pressure-controlled electronic braking assembly directly connected to a second pressurized fluid control input of the second pressure-controlled electronic braking assembly.

In another aspect combinable any one of the previous aspects, the second pressure-controlled electronic braking assembly includes a first pressurized fluid control output fluidly coupled to one of the plurality of vehicle brake sets and a second pressurized fluid control output fluidly coupled to another of the plurality of vehicle brake sets.

Another aspect combinable any one of the previous aspects further includes a vehicle operator brake pedal including a first pressurized fluid control output connected to a first pressurized fluid control input of the first pressure-controlled electronic braking assembly and a second pressurized fluid control output connected to a second pressurized fluid control input of the first pressure-controlled electronic braking assembly.

In another aspect combinable any one of the previous aspects, each of the plurality of electronic control units is configured to command at least one of the first or second pressure-controlled electronic braking assemblies to adjust the pressure of at least one pressurized fluid stream from the at least one of the first or second pressure-controlled electronic braking assemblies to the at least one vehicle brake set based at least in part on sensor output from the one or more vehicle sensors in an absence of a pressurized fluid output from either of the first pressurized fluid control output of the vehicle operator brake pedal or the second pressurized fluid control output of the vehicle operator brake pedal.

In another aspect combinable any one of the previous aspects, the one or more vehicle sensors include at least one of a radar sensor, an image sensor, or a lidar sensor.

In another aspect combinable any one of the previous aspects, each of the plurality of pressure-controlled electronic braking assemblies includes a trailer electronic braking assembly.

In another aspect combinable any one of the previous aspects, the at least one pressurized fluid stream includes a pneumatic fluid stream.

In another aspect combinable any one of the previous aspects, the plurality of electronic control units are communicably coupled to the first and second pressure-controlled electronic braking assemblies on a communication network.

Another aspect combinable any one of the previous aspects further includes a plurality of pressurized fluid control valves.

In another aspect combinable any one of the previous aspects, each of the pressurized fluid control valves communicably coupled to at least one of the electronic control units and fluidly coupled to a vehicle parking brake.

In another aspect combinable any one of the previous aspects, each of the plurality of electronic control units configured to command at least one of the pressurized fluid control valves to adjust a pressure of at least one pressurized fluid stream from the at least one of the first or second pressure-controlled electronic braking assemblies to the vehicle parking brake based at least in part on sensor output from the one or more vehicle sensors.

In another aspect combinable any one of the previous aspects, the plurality of pressurized fluid control valves are fluidly coupled in series with a binary valve positioned between the pressurized fluid control valves and the vehicle parking brake.

In another aspect combinable any one of the previous aspects, the binary valve is further fluidly coupled to an operator parking brake actuator through an operator parking brake control valve.

In another example implementation, a method for braking an autonomous vehicle includes providing at least one pressurized fluid stream from at least one of a plurality of pressurized fluid sources to a plurality of pressure-controlled electronic braking assemblies of an autonomous vehicle, where each pressure-controlled electronic braking assembly fluidly coupled to at least one vehicle brake set of a plurality of vehicle brake sets of the autonomous vehicle; providing the at least one pressurized fluid stream from a pressurized fluid control output of a first pressure-controlled electronic braking assembly of the plurality of pressure-controlled electronic braking assemblies directly to a pressurized fluid control input of a second pressure-controlled electronic braking assembly of the plurality of pressure-controlled electronic braking assemblies; providing the at least one pressurized fluid stream from the second pressure-controlled electronic braking assembly to the at least one vehicle brake set; providing sensor output data from one or more vehicle sensors of the autonomous vehicle to a plurality of electronic control units, each of the plurality of electronic control units communicably coupled to the first and second pressure-controlled electronic braking assemblies; and based at least in part on the sensor output data, controlling, with at least one of the electronic control units, at least one of the first or second pressure-controlled electronic braking assemblies to adjust a pressure of the at least one pressurized fluid stream from the at least one of the first or second pressure-controlled electronic braking assemblies to the at least one vehicle brake set.

In an aspect combinable with the example implementation, providing at least one pressurized fluid stream from at least one of a plurality of pressurized fluid sources to a plurality of pressure-controlled electronic braking assemblies of an autonomous vehicle includes providing a first pressurized fluid from a first pressurized fluid source to the first and second pressure-controlled electronic braking assemblies; and providing a second pressurized fluid from a second pressurized fluid source to the first and second pressure-controlled electronic braking assemblies.

In another aspect combinable any one of the previous aspects, providing the at least one pressurized fluid stream from the pressurized fluid control output of the first pressure-controlled electronic braking assembly of the plurality of pressure-controlled electronic braking assemblies directly to the pressurized fluid control input of the second pressure-controlled electronic braking assembly of the plurality of pressure-controlled electronic braking assemblies includes providing the first pressurized fluid from a first pressurized fluid control output of the first pressure-controlled electronic braking assembly directly to a first pressurized fluid control input of the second pressure-controlled electronic braking assembly; and providing the second pressurized fluid from a second pressurized fluid control output of the first pressure-controlled electronic braking assembly directly to a second pressurized fluid control input of the second pressure-controlled electronic braking assembly.

In another aspect combinable any one of the previous aspects, providing the at least one pressurized fluid stream from the second pressure-controlled electronic braking assembly to the at least one vehicle brake set includes providing the first pressurized fluid from a first pressurized fluid control output of the second pressure-controlled electronic braking assembly to one of the plurality of vehicle brake sets; and providing the second pressurized fluid from a second pressurized fluid control output of the second pressure-controlled electronic braking assembly to another of the plurality of vehicle brake sets.

Another aspect combinable any one of the previous aspects further includes providing the first and second pressurized fluid streams to a vehicle operator brake pedal; providing the first pressurized fluid stream from a first pressurized fluid control output of the vehicle operator brake pedal to a first pressurized fluid control input of the first pressure-controlled electronic braking assembly; providing the second pressurized fluid stream from a second pressurized fluid control output of the vehicle operator brake pedal to a second pressurized fluid control input of the first pressure-controlled electronic braking assembly; adjusting, based on operator input, a pressure of at least one of the first or second pressurized fluid streams with the vehicle operator brake pedal; and providing the adjusted at least one of the first or second pressurized fluid streams through the first and second pressure-controlled electronic braking assemblies and to the at least one vehicle brake set.

In another aspect combinable any one of the previous aspects, providing the adjusted at least one of the first or second pressurized fluid streams through the first and second pressure-controlled electronic braking assemblies includes providing the adjusted at least one of the first or second pressurized fluid streams through the first and second pressure-controlled electronic braking assemblies and to the at least one vehicle brake set at an unchanged pressure.

In another aspect combinable any one of the previous aspects, providing sensor output data from one or more vehicle sensors of the autonomous vehicle to a plurality of electronic control units includes providing at least one of radar sensor data, image sensor data, or lidar sensor data.

In another aspect combinable any one of the previous aspects, each of the plurality of pressure-controlled electronic braking assemblies includes a trailer electronic braking assembly.

In another aspect combinable any one of the previous aspects, the at least one pressurized fluid stream includes a pneumatic fluid stream.

In another aspect combinable any one of the previous aspects, the plurality of electronic control units are communicably coupled to the first and second pressure-controlled electronic braking assemblies on a communication network.

Another aspect combinable any one of the previous aspects further includes providing the at least one pressurized fluid stream from the at least one of the plurality of pressurized fluid sources to a plurality of pressurized fluid control valves that are fluidly coupled to a vehicle parking brake through a binary valve; providing additional sensor output data from the one or more vehicle sensors of the autonomous vehicle to the plurality of electronic control units, each of the plurality of electronic control units communicably coupled to a first or a second pressurized fluid control valves of the plurality of pressurized fluid control valves; based at least in part on the sensor output data, controlling, with at least one of the electronic control units, at least one of the first or second pressurized fluid control valves to pass the pressurized fluid stream to the binary valve; based on a pressure of the pressurized fluid stream passed to the binary valve from the at least one of the first or second pressurized fluid control valves being greater than a pressurized fluid stream passed to the binary valve from a third pressurized fluid control valve fluidly coupled to an operator parking brake, actuating the vehicle parking brake.

In another example implementation, an autonomous vehicle includes a vehicle frame; one or more vehicle sensors coupled with the vehicle frame; a plurality of wheels coupled to the vehicle frame; at least one vehicle brake set coupled to at least a portion of the plurality of wheels; and a vehicle braking system. The vehicle braking system includes a plurality of pressurized fluid supplies, a plurality of pressure-controlled electronic braking assemblies, and a plurality of electronic control units. Each pressure-controlled electronic braking assembly is fluidly coupled to at least one of the plurality of pressurized fluid supplies. A pressurized fluid control output of one of the plurality of pressure-controlled electronic braking assemblies is plumbed to a pressurized fluid control input of another of the plurality of pressure-controlled electronic braking assemblies. Each of the plurality of electronic control units is communicably coupled to the plurality of pressure-controlled electronic braking assemblies and the one or more vehicle sensors. The plurality of electronic control units are configured to perform operations including receiving sensor data from the one or more vehicle sensors; and based on the received sensor data, controlling at least one of the plurality of pressure-controlled electronic braking assemblies to adjust a pressure of a pressurized fluid circulated from at least one of the plurality of pressurized fluid supplies, through the at least one of the pressure-controlled electronic braking assemblies, to the at least one vehicle brake set.

In an aspect combinable with the example implementation, the autonomous vehicle includes a class 8, L4 autonomous vehicle.

In another aspect combinable any one of the previous aspects, a first brake sub-assembly includes a combination of a first pressure-controlled electronic braking assembly and a first electronic control unit.

In another aspect combinable any one of the previous aspects, a second brake sub-assembly includes a combination of a second pressure-controlled electronic braking assembly different than the first pressure-controlled electronic braking assembly and a second electronic control unit different than the first electronic control unit.

In another aspect combinable any one of the previous aspects, one of the first or second brake sub-assemblies is configured to adjust the pressure of the pressurized fluid circulated from the at least one of the plurality of pressurized fluid supplies, through the respective first or second pressure-controlled electronic braking assembly, to the at least one vehicle brake set based on the received sensor data independent of the other of the first or second brake sub-assemblies.

Example implementations according to the present disclosure may include one, some, or all of the following features. For example, implementations of the present disclosure may include a vehicle braking system that provides redundant, high resolution wheel speed odometry and speed. As another example, implementations of the present disclosure may include a vehicle braking system that provides both instantaneous wheel speeds and cumulative ticks as well as directionality. As another example, implementations of the present disclosure may include a vehicle braking system that is suitable for an L4 application and that minimizes or completely eliminates the need for any hardware modifications of existing braking system components (e.g., such as pressure-actuated brake assemblies) and can be implemented with only software or firmware changes. As another example, implementations of the present disclosure may include a vehicle braking system that provides a high quality, high reliability, redundant braking interface that is suitable for an L4 enabled self-driving system. Implementations of the present disclosure also may include an elegant parking brake implementation that has favorable failure modes and can be operated in both manual and automated modes.

DETAILED DESCRIPTION

This disclosure describes example implementations of vehicle braking systems and methods, such as braking systems and methods for autonomous vehicles. In some aspects, example implementations of the vehicle braking systems may include one or more redundant braking components, such as redundant pressure-controlled braking assemblies and redundant electronic control units, to provide for failsafe braking of, e.g., an autonomous vehicle.

FIG. 1is an example implementation of a vehicle100that includes a vehicle braking system112according to the present disclosure. Although the illustrated vehicle100is shown as a class 8 vehicle (e.g., a tractor trailer vehicle), the term “vehicle” in the present disclosure may also include another type of vehicle, such as a personal car, other personal or commercial trucks, and other vehicles (e.g., nautical or aeronautical vehicles). Vehicle100, as shown, includes a tractor102and a trailer104, each of which form part of a vehicle frame (in this example) that includes wheel sets106(front tractor wheels),108(rear tractor wheels), and110(trailer wheels). One or more vehicle brake sets (or, vehicle brakes)114,116,118,122are associated with each of the wheel sets106,108, and110.

The vehicle100inFIG. 1can be a fully autonomous vehicle that determines and executes fully-autonomous driving decisions in order to navigate through an environment (e.g., a Level2through Level5automated vehicle according to the Society of Automotive Engineers (SAE)). The vehicle102can also be a semi-autonomous vehicle that uses predictions to aid a human driver. For example, the vehicle102, as described more fully herein, can autonomously apply one or more sets of vehicle brakes114,116,118, and122if a prediction indicates that a human driver is about to collide with another vehicle.

The vehicle100includes one or more sensors140. The sensors140include, in this example implementation, a combination of components that receive reflections of electromagnetic radiation, e.g., lidar systems that detect reflections of laser light, radar systems that detect reflections of radio waves, and camera systems that detect reflections of visible light. The sensor data generated by a given sensor generally indicates a distance, a direction, or an intensity of reflected radiation (or a combination thereof). For example, a sensor can transmit one or more pulses of electromagnetic radiation in a particular direction and can measure the intensity of any reflections as well as the time that the reflection was received. A distance can be computed by determining how long it took between a pulse and its corresponding reflection. The sensor can continually sweep a particular space in angle, azimuth, or both. Sweeping in azimuth, for example, can allow a sensor to detect multiple objects along the same line of sight.

Thus, in some aspects, the one or more sensors140may provide data that indicates a distance between the vehicle100and another object (e.g., a vehicle or otherwise) adjacent the tractor102of the vehicle100. The provided data can be communicated, e.g., to the vehicle braking system112, which may use the data to actuate one or more of the vehicle brakes114,116,118,122.

In this example, the vehicle brakes114,116,118,122may include, e.g., front axle brakes, trailer brakes, foundation brakes, and parking brakes, respectively. Generally, the vehicle brakes114-118act as conventional brakes. For example, the vehicle brakes114-118may be pressure-actuated (e.g., hydraulically, pneumatically, or otherwise) to move a brake pad against a disc brake to create friction to slow and possibly stop the vehicle102. The parking brake (vehicle brake122) may be actuated to prevent unwanted movement of the vehicle100from a stationary position or, in extreme instances, actuated to quickly bring a “runaway” vehicle100to a stop.

The vehicle braking system112, generally and discussed in more detail herein, may provide for a redundant braking interface (e.g., with primary and fallback interfaces are the same control method) that includes two or more pressure-controlled electronic brake assemblies connected in series and powered (electrically) from a low voltage vehicle bus (e.g., a 12 V bus). Each of the pressure-controlled electronic brake assemblies may be a trailer electronic brake (TEB) module (or a trailer electronic braking system (TEBS)), such as a TEBS E module from WABCO. In some aspects, the vehicle braking system112may include redundant interfaces to permanently secure the vehicle100in a parked state; a first interface may be through an electronic parking brake control over a vehicle communication network (e.g., a CAN bus network), while a second interface may be through a mechanical fail-on valve actuation when a supply pressure of a pressurized fluid drops below threshold value.

FIG. 2is a block diagram of an example implementation of a vehicle braking sub-system200. In some aspects, the vehicle braking sub-system200may be part of the vehicle braking system112shown inFIG. 1. Generally, the vehicle braking sub-system200may operate to actuate one or more vehicle brake sets in a vehicle. In some aspects, like vehicle100, the vehicle may be an autonomously controlled vehicle, such as an L4 autonomous vehicle that still includes an operator brake pedal. Thus, in some aspects, the vehicle braking sub-system200may operate in an autonomous or “active” mode (e.g., a normal operation for an autonomous vehicle) and a manual mode (e.g., in a non-autonomous vehicle or in an autonomous vehicle that includes an operator brake pedal).

As shown, the vehicle braking sub-system200includes a first pressure-controlled electronic braking assembly204and a second pressure-controlled electronic braking assembly206. Although this implementation includes two pressure-controlled electronic braking assemblies, alternative implementations may include more than two pressure-controlled electronic braking assemblies. Each pressure-controlled electronic braking assembly204and206, in this illustrated implementation, may be a TEB (or TEBS), which is connected to one or more pressurized-fluid sources and includes one or more pressure-control inputs and one or more pressure control outputs. In some aspects, the pressure-controlled electronic braking assemblies204and206operate with a pneumatic pressurized fluid, such as air or other gas. In alternative aspects, the pressure-controlled electronic braking assemblies204and206operate with a hydraulic pressurized fluid, such as a liquid. Each pressure-controlled electronic braking assembly204and206may operate to adjust a pressure of a pressurized fluid input to the particular pressure-controlled electronic braking assembly to provide a pressurized fluid output of the pressurized fluid at the adjusted pressure.

As shown in this figure, pressurized fluid source216and pressurized fluid source218are both connected to each pressure-controlled electronic braking assembly204and206to supply two pressurized fluid streams224and226. In this example, both pressurized fluid streams224and226are supplied to an operator brake pedal202, the pressure-controlled electronic braking assembly204, and the pressure-controlled electronic braking assembly206.

In this example, the pressure-controlled electronic braking assembly204is connected between the operator brake pedal202and the pressure-controlled electronic braking assembly206. Pressurized fluid control outputs232and234from the pressure-controlled electronic braking assembly204are both directly connected (e.g., plumbed) to the pressure-controlled electronic braking assembly206. Thus, as shown in this figure, the pressurized fluid control outputs232and234from the pressure-controlled electronic braking assembly204are also pressurized fluid control inputs232and234for the pressure-controlled electronic braking assembly206(e.g., a pressure of the pressurized fluid stream232output from pressure-controlled electronic braking assembly204is the same or negligibly different than the pressure of the pressurized fluid stream232input to pressure-controlled electronic braking assembly206).

The pressure-controlled electronic braking assembly206includes a pressurized fluid control output236and a pressurized fluid control output238to provide pressurized fluid streams to actuate one or more vehicle brake sets of the vehicle. For example, the pressurized fluid stream of pressurized fluid control output236may be provided to a first vehicle brake set (or sets), such as the front axle and trailer brake sets (e.g., for the illustrated vehicle100ofFIG. 1). The pressurized fluid stream of pressurized fluid control output238may be provided to a second vehicle brake set (or sets), such as the rear axle and trailer brake sets (e.g., for the illustrated vehicle100ofFIG. 1).

The operator brake pedal202may be actuated by a vehicle (human) operator to provide a pressurized fluid control output228and a pressurized fluid control output230to the pressure-controlled electronic braking assembly204. A pressure of the pressurized fluid of pressurized fluid control output228and pressurized fluid control output230is controlled (e.g., adjusted) based on actuation of the operator brake pedal202.

The illustrated vehicle braking sub-system200includes electric power sources220and222that provide electrical power240and242(e.g., 12 V power) to the pressure-controlled electronic braking assemblies204and206, respectively. Thus, as shown, there are redundant sources of electrical power for the vehicle braking sub-system200.

The illustrated vehicle braking sub-system200also includes a first electronic control unit (ECU)208and a second electronic control unit (ECU)210(powered by the electrical power240and242, respectively). As shown, the ECU208is communicably connected to the pressure-controlled electronic braking assembly204through network connection244(e.g., on a CAN bus network). The ECU208is also communicably connected to the pressure-controlled electronic braking assembly206through the pressure-controlled electronic braking assembly204and network connection246. As shown, the ECU210is communicably connected to the pressure-controlled electronic braking assembly206through network connection248(e.g., on a CAN bus network). The ECU210is also communicably connected to the pressure-controlled electronic braking assembly204through the pressure-controlled electronic braking assembly206and network connection246. Each ECU, generally, comprises a micro-processor based controller that, e.g., receives data from the vehicle (such as one or more vehicle sensors140) and controls operation of the pressure-controlled electronic braking assemblies204and206to control or adjust a pressure of one or more pressurized fluid streams (e.g.,236and238) provided to actuate one or more vehicle brake sets. As shown, each ECU208and210are communicably coupled to one or more additional ECUs212or214through the illustrated network communications244and248. The additional ECUs212and214may control other components of the vehicle besides the one or more vehicle brake sets.

In operation (in the case of an autonomous vehicle), the vehicle braking sub-system200may operate in active mode, in which the ECUs208and210control operation of the pressure-controlled electronic braking assemblies204and206based on, e.g., receipt of vehicle sensor data from the vehicle sensors140. For example, if the vehicle sensor data does not indicate a need for braking or stopping the vehicle, the ECUs208and210may not operate to control the respective pressure-controlled electronic braking assemblies204and206to adjust a pressure of the pressurized fluid control outputs236and238to actuate the one or more vehicle brake sets. If the vehicle sensor data does indicate a need for braking or stopping the vehicle, the ECUs208and210operate to control the respective pressure-controlled electronic braking assemblies204and206to adjust the pressure of the pressurized fluid control outputs236and238to actuate the one or more vehicle brake sets.

Even when the vehicle is an autonomous vehicle (e.g., an L4 vehicle), the vehicle braking sub-system200may operate in manual mode as well. In manual mode, the operator brake pedal202may be adjusted (by the human vehicle operator) to adjust the pressure of the pressurized fluid control outputs228and230. As this adjustment raises the pressure of the pressurized fluid greater than that of the control outputs232and234, the pressurized fluid control outputs228and230may pass through the pressure-controlled electronic braking assemblies204and206without further adjustment to the control outputs236and238(and to the one or more vehicle brake sets). Thus, in some aspects, even when the vehicle braking sub-system200is operating in active mode, the pressure-controlled electronic braking assemblies204and206do not (and cannot) prevent the operator brake pedal202from being actuated to build brake pressure due to a mechanical “highest pressure wins” valve inside the pressure-controlled electronic braking assemblies204and206.

During operation, the pressure-controlled electronic braking assemblies204and206may monitor control input pressure (e.g.,228and230to pressure-controlled electronic braking assembly204and232and234to pressure-controlled electronic braking assembly206) and control output pressures (e.g.,228and230from operator brake pedal202,232and234from pressure-controlled electronic braking assembly202, and236and238from pressure-controlled electronic braking assembly204) and report these over network communications244,246, and248. Such signals are used to detect normal operating conditions, driver brake actuations, as well as fault conditions. For example, as for fault modes, in some aspects, no single network communication fault (e.g., CAN bus fault) can interrupt all communications between the ECUs208and210and the pressure-controlled electronic braking assemblies204and206. Also, no single hardware/pressurized-fluid fault may prevent the ECUs208and210from operating to build brake pressure in the pressure-controlled electronic braking assemblies204and/or206through the network communication interfaces244,246, and248.

During operation, the pressure-controlled electronic braking assemblies204and206may not interfere with and are unaffected by other ECUs212and214operating on the network communications (e.g., other CAN bus nodes). Further, the pressure-controlled electronic braking assemblies204and206may appear as similar nodes to an anti-lock braking (ABS) system of a vehicle as does the operator brake pedal202, thereby allowing brake control of the one or more vehicle brake sets from the pressure-controlled electronic braking assemblies202and204to pass through standard ABS and vehicle electronic stability control (ESC) functional blocks of the pressure-controlled electronic braking assemblies202and204as conventionally designed in these component.

FIG. 3is a block diagram of an example implementation of another vehicle braking sub-system300according to the present disclosure. In some aspects, the vehicle braking sub-system300may be part of the vehicle braking system112shown inFIG. 1and also include some components of the vehicle braking sub-system200shown inFIG. 2. Generally, the vehicle braking sub-system300may operate to actuate a parking brake in a vehicle. In some aspects, like vehicle100, the vehicle may be an autonomously controlled vehicle, such as an L4 autonomous vehicle that still includes an operator parking brake. Thus, in some aspects, the vehicle braking sub-system300may operate in an autonomous or “active” mode (e.g., a normal operation for an autonomous vehicle) and a manual mode (e.g., in a non-autonomous vehicle or in an autonomous vehicle that includes an operator parking brake).

As shown, the vehicle braking sub-system300includes an operator parking brake302that is connected to pressurized fluid sources216and218to receive pressurized fluid streams224and226. A pressurized fluid control output314from the operator parking brake320connects to a control valve310, with a pressure sensor308in communication with the output314to provide a sensed pressure value of the pressurized fluid in the control output314. The control valve is also communicably coupled to the ECU208through network communication244. InFIG. 3, a dashed line as shown in a control valve represents an “ON” state when the pathway through the valve is powered, while a solid line shown in a control valve represents an “OFF” state when the pathway through the valve is not powered or when the valve is in a failed state.

As further shown, a control valve304is communicably coupled to the ECU210on the network communication interface248and is also fluidly coupled to the pressurized fluid sources216and218to receive pressurized fluid streams224and226. A pressurized fluid control output322is connected from the control valve304to a control valve306as well as control valve310. In the example implementation, a pressure sensor312is in communication with the output322to provide a sensed pressure value of the pressurized fluid in the control output322upstream of the control valve310.

The control valve306is communicably coupled to the ECU208on the network communication interface244. The control valve306receives the pressurized fluid control output322from the control valve304(as an input) and provides a pressurized fluid control output324to a binary valve316(e.g., an “or” valve that allows a high pressurized fluid to pass through). The control valve310also provides a pressurized fluid control output326to the binary valve316. A pressurized fluid control output328is connected from the binary valve316to a vehicle parking brake320(e.g., tractor parking brake, trailer parking brake, or both). A pressure sensor318is in communication with the output328to provide a sensed pressure value of the pressurized fluid in the control output328downstream of the binary valve316.

In some aspects, the vehicle braking sub-system300allows a conventional pressure actuated (e.g., pneumatic or hydraulic) parking brake to be implemented in an autonomous vehicle braking system (e.g., system112) without interfering with operator control of the vehicle parking brake320. For example, when the vehicle braking sub-system300is operating in a manual mode (e.g., even in an autonomous vehicle such as an L4 vehicle). During a manual mode, e.g., when the ECUs208and210are not commanding the control valves306,304, and310, and they are in their default state, the operator parking brake302operates conventionally to apply the vehicle parking brake320(e.g., to keep the vehicle at a stationary position). In some aspects, the operation of the vehicle parking brake320by the operator parking brake302in a manual mode is not changed relative to conventional operation, e.g., for a Class 8 truck in this industry. Further, in some aspects, the fault modes of the vehicle braking sub-system300are unchanged relative to conventional Class 8 parking brake system layouts in the manual mode, e.g., portion of the vehicle parking brake320that includes the operator parking brake302.

As shown,FIG. 3shows a single circuit (e.g., single vehicle braking sub-system300) that describes an example implementation of the sub-system300for, e.g., a tractor of a Class 8 vehicle. In some aspects, the example implementation of the sub-system300may be duplicated for, e.g., a trailer of the Class 8 vehicle (i.e., a parking brake system for the system). For instance, control valves, such as control valves304,306,310, and316would be duplicated. Further, for instance, the operator parking brake302may include a standard square yellow push-pull knob for trailer parking brake actuation. Thus, in some aspects, the vehicle100may include two vehicle braking sub-systems300, where a first vehicle braking sub-system300controls a tractor parking brake and a second vehicle braking sub-system300controls a trailer parking brake.

In an active mode (e.g., autonomous vehicle control by the ECUs208and210), the operator parking brake302may be set to “apply parking brake” such that in the event of a dual failure of power (e.g., electrical or pressurized fluid) or network communication, the vehicle parking brake320is applied (e.g., automatically and mechanically). As shown in vehicle braking sub-system300, the layout of the control valves304,306and310(and binary OR valve316) provides that even if any single control valve (304,306,310) becomes stuck or faults to the wrong location, the vehicle braking sub-system300still has full control over the parking brake (e.g., can still apply and release the vehicle parking brake300).

For example, as shown inFIG. 3, the control valves304,306, and310are shown with default (solid line) and non-default (dashed line) positions. Control valves304and306have default positions that fluidly decouple the pressurized fluid streams224and226from the binary OR valve316, while the control valve310has a default position that fluidly couples the pressurized fluid streams224and226with the binary OR valve316. During autonomous operation control, however, should one or both of the ECUs208and210determine that the vehicle parking brake320should be applied (e.g., in the case of a runaway vehicle situation) even when the operator parking brake302is not applied, one or both of the ECUs208or210may set control valves304and306to their default positions, thereby exhausting pressure in pressurized fluid output324to actuate the vehicle parking brake320through the binary OR valve316. Control valve310can also be set to either default or non-default position by the ECU208in such a manner as to actuate the vehicle parking brake320(exhausting air pressure in pressurized fluid output326) through either output314and operator parking brake302or through pressurized fluid output322.

As the pressurized fluid control output324may be greater than the pressurized fluid output326, the binary OR valve316passes the pressurized fluid control output324to actuate the vehicle parking brake320. In the case where any single control valve shown inFIG. 3is in an incorrect position, the cross-circuit control valves combined with the binary OR valve316provides full control authority via either the operator circuit (e.g., the pressurized fluid circuit that includes the operator parking brake302) or the autonomous circuit (e.g., the pressurized fluid circuit that includes control valves304and306controlled by the ECUs208and210).

During operation of the vehicle braking sub-system300, in some aspects, no single network communication interface (e.g., CAN bus) fault or digital I/O fault can accidentally apply or release the vehicle parking brake320. Further, in some aspects, no single hardware/pressurized fluid fault can cause faulty application of the vehicle parking brake320or prevent one or both of the ECUs208and210from applying or releasing the vehicle parking brake320. In some aspects, in the event of a dual network communication or power (e.g., electrical or pressurized fluid) fault, the vehicle braking sub-system300may apply the vehicle parking brake automatically as a failsafe fault mode (e.g., to prevent a runaway autonomous vehicle).

FIG. 4is a flowchart that describes an example method400for braking a vehicle according to the present disclosure. For example, in some aspects, the method400may be implemented by or with the vehicle braking sub-system200as shown and described inFIG. 2. Alternatively, the method400may be implemented by or with a vehicle braking sub-system in accordance with the present disclosure. Method400may begin at step402, which includes operating an autonomous vehicle. For example, the vehicle may be an L2-5 vehicle, such as an L4 vehicle. In some aspects, the vehicle is a class 8 tractor-trailer autonomous vehicle. The autonomous vehicle may be operated (e.g., driven, navigated) by one or more electronic control units (ECUs) in combination with one or more vehicle sensors that provide sensor data to the ECUs for navigation determinations.

Method400may continue at step404, which includes providing at least one pressurized fluid stream from at least one pressurized fluid source to a plurality of pressure-controlled electronic braking assemblies. For example, in some aspects, there are multiple (e.g., two) pressurized fluid streams that are provided from independent and separate pressurized fluid sources on the vehicle (e.g., hydraulic or pneumatic sources).

Method400may continue at step406, which includes providing the at least one pressurized fluid stream from a pressurized fluid control output of a first pressure-controlled electronic braking assembly directly to a pressurized fluid control input of a second pressure-controlled electronic braking assembly. For example, the pressurized fluid streams are provided separately to independent and separate pressure-controlled electronic braking assemblies. In some aspects, one of the pressure-controlled electronic braking assemblies is directly plumbed to another pressure-controlled electronic braking assembly (e.g., in a series arrangement). Thus, in some aspects, a first pressurized fluid stream is provided from an output of the first pressure-controlled electronic braking assembly directly (e.g., without pressure change) to an input of the second pressure-controlled electronic braking assembly. Further, step406may also include providing a second pressurized fluid stream from another output of the first pressure-controlled electronic braking assembly directly (e.g., without pressure change) to another input of the second pressure-controlled electronic braking assembly.

Method400may continue at step408, which includes providing the at least one pressurized fluid stream from the second pressure-controlled electronic braking assembly to at least one vehicle brake set. For example, in some aspects, the autonomous vehicle may have multiple brake sets, each of which is actuated separately but simultaneously. In some aspects, the second pressure-controlled electronic braking assembly is fluidly connected to each of the multiple vehicle brake sets (e.g., through separate pressurized fluid outputs from the second pressure-controlled electronic braking assembly).

Method400may continue at step410, which includes a determination of whether sensor output data from one or more vehicle sensors (e.g., image sensors, lidar sensors, radar sensors, or otherwise) that indicates a need for vehicle braking is received at the one or more ECUs (e.g., ECUs208and210as shown inFIG. 2). For example, the sensor data may indicate an upcoming object (e.g., another vehicle or otherwise) in a path of the autonomous vehicle, thereby indicating that the autonomous vehicle should brake. If the determination is yes, then method400may continue at step412, which includes providing the sensor output data to a plurality of electronic control units communicably coupled to the first and second pressure-controlled electronic braking assemblies. For example, the sensor output data may be provided to the one or more ECUs (e.g., ECUs208and210as shown inFIG. 2) for a determination of whether braking (and how much braking) is needed. If the determination of step410is no, then method400may return to step402.

Method400may continue at step414, which includes controlling, with at least one of the electronic control units, at least one of the first or second pressure-controlled electronic braking assemblies to adjust a pressure of the at least one pressurized fluid stream. For example, one or more of the ECUs may control one or more internal valves or pathways of the at least one of the first or second pressure-controlled electronic braking assemblies in order to adjust (e.g., increase) a pressure of the at least one pressurized fluid stream. As in conventional braking (e.g., non-autonomous vehicle braking), an increased pressure of a pressurized fluid actuates the vehicle brakes.

Method400may continue at step416, which includes providing the adjusted pressurized fluid stream to the at least one vehicle brake set to brake the vehicle. For example, the at least one vehicle brake set could be tractor brakes or trailer brakes or both.

Method400may continue at step418, which includes providing the first and second pressurized fluid streams to a vehicle operator brake pedal. For example, even in the case of most autonomous vehicles (including L4 autonomous vehicle), an operator brake pedal is provided such that a human operator of the vehicle can brake the vehicle at any time. As shown inFIG. 2, an operator brake pedal is integrated into the vehicle braking sub-system for autonomous braking of the vehicle.

Method400may continue at step420, which includes providing the first pressurized fluid stream from a first pressurized fluid control output of the vehicle operator brake pedal to a first pressurized fluid control input of the first pressure-controlled electronic braking assembly. Method400may continue at step422, which includes providing the second pressurized fluid stream from a second pressurized fluid control output of the vehicle operator brake pedal to a second pressurized fluid control input of the first pressure-controlled electronic braking assembly. For example, the vehicle operator brake pedal may be connected in series with the first and second pressure-controlled electronic braking assemblies and upstream of the first pressure-controlled electronic braking assembly (e.g., with the first pressure-controlled electronic braking assembly connected between the operator brake pedal and the second pressure-controlled electronic braking assembly). Thus, there may be two separate and independent pressurized fluid control conduits (with inputs and outputs) that connect the operator brake pedal with the first pressure-controlled electronic braking assembly that is connected to the second pressure-controlled electronic braking assembly).

Method400may continue at step424, which includes a determination of whether the human operator actuates the operator brake pedal. If the determination is yes, then method400may continue at step426, which includes adjusting a pressure of at least one of the first or second pressurized fluid streams with the vehicle operator brake pedal. For example, as with conventional (e.g., non-autonomous) vehicle braking, when the operator depresses the operator brake pedal, the pressure of the pressurized fluid that actuates the vehicle brakes is increased. In this example, actuation. Method400may then continue at step428, which includes providing the adjusted pressurized fluid streams through the first and second pressure-controlled electronic braking assemblies and to the vehicle brake set to brake the vehicle. For example, the adjusted pressure of the pressurized fluid may be greater than any other pressurized fluid control outputs from the pressure-controlled electronic braking assemblies and thus, may pass through the pressure-controlled electronic braking assemblies unchanged to actuate the one or more vehicle brake sets. Thus, in some aspects, actuation of the operator brake pedal may provide a pressure of the pressurized fluid that overrides any control of the pressure-controlled electronic braking assemblies (e.g., to adjust the pressurized fluid passing therethrough) by the ECUs. If the determination in step424is no, then method400may return to step402.

In this specification the term “controller” or “electronic control unit” is used broadly to refer to a software-based system, subsystem, or process that is programmed to perform one or more specific functions. Generally, a controller or electronic control unit may be implemented as one or more software modules or components, installed on one or more computers in one or more locations. The processes and logic flows described in this specification can be performed by one or more programmable controllers or electronic control units executing one or more computer programs to perform functions by operating on input data and generating output. The processes and logic flows can also be performed by special purpose logic circuitry, e.g., an FPGA or an ASIC, or by a combination of special purpose logic circuitry and one or more programmed computers.