Computer-implemented method, computing device and storage medium

Abstract

The present disclosure provides a computer-implemented method for reducing current in a vehicle brake to conserve power, the method comprising: applying a first current to a brake system of a vehicle after the vehicle has stopped moving on a slope, the first current preventing the vehicle from moving on the slope; determining a first brake pressure based on the first current and the slope; determining a second current based on the first brake pressure and a brake hysteresis, wherein the second current is lower than the first current; and reducing the first current in the brake system to the second current.

Description

Technical Field

[0001] The embodiments of this disclosure generally relate to operating autonomous vehicles. More specifically, embodiments of this disclosure relate to a computer-implemented method, computing device, and storage medium. Background Technology

[0002] Vehicles operating in automatic mode (such as driverless vehicles) can reduce some driving-related tasks for occupants, especially the driver. When a vehicle is in automatic mode, onboard sensors can be used to navigate the vehicle to different locations, thus minimizing human-machine interaction or allowing the vehicle to operate without passengers.

[0003] Braking control is a critical operation. Most autonomous or driver-assisted (AD) vehicles use electricity to operate the braking system (e.g., indirectly via a hydraulic / pneumatic system, where an electric motor powers a pump or valve; or directly actuating components that cause friction). Braking systems can consume electricity wastefully and reduce overall operational efficiency. For example, when the vehicle is stationary during operation (e.g., without mechanical locking engagement), the electrical consumption in the braking system will be significant, regardless of how much braking power is needed to keep the vehicle stationary. This wasteful operation negatively impacts other aspects that require electricity, such as restarting the internal combustion engine. Summary of the Invention

[0004] According to embodiments of this disclosure, a computer-implemented method, a computing device, and a computer-readable storage medium are provided.

[0005] According to one aspect of the present disclosure, a computer-implemented method is provided for reducing the current during vehicle braking to save power, the method comprising: applying a first current to the vehicle's braking system after the vehicle has stopped moving on a slope, the first current preventing the vehicle from moving on the slope; determining a first braking pressure based on the first current and the slope; determining a second current based on the first braking pressure and braking hysteresis, wherein the second current is lower than the first current; and reducing the first current in the braking system to the second current.

[0006] According to another aspect of the present disclosure, a computing device is provided, comprising: a memory storing executable instructions; and a processing means coupled to the memory, the processing means being configured to execute the executable instructions to perform the following operations: after a vehicle stops moving on a slope, applying a first current to the braking system of the vehicle, the first current preventing the vehicle from moving on the slope; determining a first braking pressure based on the first current and the slope; determining a second current based on the first braking pressure and braking hysteresis, wherein the second current is lower than the first current; and reducing the first current in the braking system to the second current.

[0007] According to another aspect of the present disclosure, a non-transitory computer-readable medium storing instructions that, when executed by a processing device, cause the processing device to perform the following operations: after a vehicle stops moving on a slope, applying a first current to the vehicle's braking system, the first current preventing the vehicle from moving on the slope; determining a first braking pressure based on the first current and the slope; determining a second current based on the first braking pressure and braking hysteresis, wherein the second current is lower than the first current; and reducing the first current in the braking system to the second current.

[0008] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this disclosure, nor is it intended to limit the scope of this disclosure. Other features of this disclosure will become readily apparent from the following description. Attached Figure Description

[0009] Embodiments of this disclosure are shown in the accompanying drawings by way of example rather than limitation, wherein similar reference numerals denote similar elements.

[0010] Figure 1 This is a block diagram illustrating a networked system according to various aspects of this disclosure.

[0011] Figure 2 This is a block diagram illustrating an example of an autonomous / assisted driving (AD) vehicle according to various aspects of this disclosure.

[0012] Figure 3 This is a block diagram illustrating an example of an AD system for an autonomous vehicle according to various aspects of this disclosure.

[0013] Figure 4 This is a block diagram illustrating an example of a braking system according to various aspects of this disclosure.

[0014] Figure 5 This is a block diagram illustrating the implementation of AD control and braking control according to various aspects of this disclosure.

[0015] Figure 6 An example application of braking hysteresis for reducing power consumption in a braking system, according to various aspects of this disclosure, is shown.

[0016] Figure 7 This is a flowchart illustrating a method for reducing current in a braking system according to various aspects of this disclosure.

[0017] Figure 8 This is a flowchart illustrating a method for obtaining a braking system hysteresis reference according to various aspects of this disclosure.

[0018] Figure 9 This is a block diagram illustrating the operation of the hysteresis determination module according to various aspects of this disclosure.

[0019] Figure 10 An example of determining braking hysteresis characteristics according to various aspects of this disclosure is shown.

[0020] Figure 11 An example of determining braking hysteresis characteristics according to various aspects of this disclosure is shown.

[0021] Figure 12 This is a flowchart illustrating a method for applying braking hysteresis characteristics during operation according to various aspects of this disclosure.

[0022] Figure 13 The following are shown in accordance with various aspects of this disclosure Figure 12 Example timelines of engine torque and battery voltage for the example method shown.

[0023] Figure 14 An example of power switching for achieving braking hysteresis characteristics according to various aspects of this disclosure is shown.

[0024] Similar reference numerals indicate similar elements. Specific Implementation

[0025] Various embodiments and aspects of this disclosure will be described with reference to the following details, and the accompanying drawings will illustrate various embodiments. The following description and drawings are illustrative and should not be construed as limiting the scope of this disclosure. Numerous specific details have been described to provide a thorough understanding of the various embodiments of this disclosure. However, in some cases, well-known or conventional details have not been described in order to concisely illustrate the embodiments of this disclosure.

[0026] The phrase "an embodiment" or "embodiment" used in the specification means that a particular feature, structure, or characteristic described in connection with that embodiment may be included in at least one embodiment of this disclosure. The phrase "in an embodiment" appearing in different locations in the specification does not necessarily refer to the same embodiment.

[0027] According to some embodiments, this disclosure provides systems and methods for saving power during braking in autonomous or assisted driving vehicles, for example, when a vehicle is temporarily stopped on a slope, while current is continuously supplied to the braking system. For example, during road checks on a slope, a vehicle can be temporarily operated while completely stopped using a conventional braking system (e.g., compared to a parking brake system). Due to the nature of braking hysteresis and the fact that static friction is greater than dynamic friction, the power required for a conventional braking system typically exceeds the actual power demand to keep the vehicle stationary. Braking hysteresis is the relationship between an input (e.g., the operating pressure caused by the electric motor to increase fluid pressure in the braking system) and an output (e.g., the braking pressure applied by the brake pads to the rotor), and the change in output differs during periods of input increase and input decrease. This disclosure provides techniques for saving power consumption by utilizing braking hysteresis, enabling better utilization of the saved power (e.g., restarting the engine in hybrid mode).

[0028] The method disclosed herein can be implemented in autonomous or driver-assisted (AD) vehicles, as well as in human-operated vehicles that utilize an electric booster to regulate the braking system. This example method can be implemented by a computer (e.g., an electronic control unit (ECU)) to reduce the current in vehicle braking to conserve power. The example method may include applying a first current to the vehicle's braking system after the vehicle has come to a stop on a slope. The first current prevents the vehicle from moving further on the slope. The computer may determine a first braking pressure based on the first current and the slope. The computer may then determine a second current based on the first braking pressure and braking hysteresis. The second current is lower than the first current. The computer then reduces the first current in the braking system to the second current.

[0029] In existing practices, during road checks, the current used to stop a vehicle is typically maintained at a level equivalent to tens of amperes (e.g., 80A), which may last for several minutes (e.g., 3 minutes or longer). Because the duration of such stopping is often uncertain, parking brakes (e.g., passive brakes) are not used, considering the inconvenience and time-consuming nature of restarting the vehicle. When the power consumption of the braking system is not well managed (e.g., power overrun), a significant and unnecessary drop in voltage and / or current occurs in the overall power supply of the vehicle. This drop negatively impacts the operation of other aspects of the vehicle, such as the powertrain, computer, etc. Furthermore, when the vehicle is parked on a slope, the power consumption of the braking system is continuous and substantial, resulting in significant power drain. This disclosure provides a method for reducing or minimizing the power consumption of the braking system in such situations without compromising braking system safety.

[0030] As described below, this disclosure utilizes braking hysteresis, which provides the same level of braking pressure output (e.g., the braking pressure applied from the brake pads to the rotor, proportional to the friction generated) while significantly reducing current input. In this way, voltage drop or power consumption can be reduced or minimized. Since most vehicles utilize electricity for computer control, independent of the power supply to the powertrain, this reduces power consumption in the ADV under such braking conditions for any vehicle type (e.g., pure electric vehicles, hybrid vehicles, or pure internal combustion engine vehicles).

[0031] The energy saved can be used for other operations in the vehicle, such as engine restarting or similar operations requiring high current consumption. In other words, the technology described herein can be applied to any type of vehicle with an electric motor to change braking pressure. For illustrative purposes, autonomous vehicles are discussed in the following examples, but the technology disclosed herein can be applied to other driver-assisted or remote-controlled vehicles with electric braking systems.

[0032] Figure 1 This is a block diagram illustrating an autonomous driving network configuration according to various aspects of this disclosure. See also Figure 1 Network configuration 100 includes an autonomous vehicle (ADV) 101, which can communicate with one or more servers 103-104 via network 102. While only one ADV is shown in the figure, multiple ADVs can be coupled to each other and / or to servers 103-104 via network 102. Network 102 can be any type of wired or wireless network, such as a local area network (LAN), a wide area network (WAN) such as the Internet, a cellular network, a satellite network, or a combination thereof. Servers 103-104 can be any type of server or server cluster, such as a web or cloud server, an application server, a backend server, or a combination thereof. Servers 103-104 can be data analytics servers, content servers, traffic information servers, map and point of interest (MPOI) servers, or location servers, etc.

[0033] An autonomous vehicle is a vehicle configurable to operate in an automatic mode, in which it can navigate with minimal or no driver input. Such an autonomous vehicle may include a sensor system with one or more sensors for detecting environmental information while the vehicle is operating. The vehicle and its associated controllers use the detected information to navigate in this environment. The autonomous vehicle 101 can operate in manual, fully automatic, or partially automatic modes.

[0034] In one embodiment, the autonomous vehicle 101 includes, but is not limited to, an Autonomous Driving System (ADS) 110, a vehicle control system 111, a wireless communication system 112, a user interface system 113, and a sensor system 115. The autonomous vehicle 101 may also include some common components found in ordinary vehicles, such as an engine, wheels, steering wheel, and transmission. These components can be controlled via the vehicle control system 111 and / or the autonomous driving system 110 using various communication signals and / or commands, such as acceleration signals or commands, deceleration signals or commands, steering signals or commands, and braking signals or commands.

[0035] Components 110-115 can be communicatively coupled to each other via interconnects, buses, networks, or combinations thereof. For example, components 110-115 can be communicatively coupled to each other via a Controller Area Network (CAN) bus. The CAN bus is a vehicle bus standard designed to enable communication between microcontrollers and devices in masterless applications. The CAN bus is a message-based protocol originally designed for multiplexing electrical wiring in automobiles, but it is also used in many other environments.

[0036] See Figure 2 In one embodiment, the sensor system 115 includes, but is not limited to, one or more cameras 211, a Global Positioning System (GPS) unit or module 212, a motion sensor 213 (e.g., an Inertial Measurement Unit (IMU), an accelerometer, etc.), a radar unit 214, and a Light Detection and Range (LIDAR) unit 215. The GPS module 212 may include a transceiver for providing information related to the location of the autonomous vehicle. The motion sensor 213 may sense changes in the position and orientation of the autonomous vehicle based on inertial acceleration. The radar unit 214 may represent a system for sensing objects within the local environment of the autonomous vehicle using radio signals. In some embodiments, in addition to sensing objects, the radar unit 214 may also sense the velocity and / or heading of objects. The LiDAR unit 215 may use lasers to sense objects in the environment in which the autonomous vehicle is located. The LiDAR unit 215 may include one or more laser sources, a laser scanner, and one or more detectors, as well as other system components. The camera 211 may include one or more devices for capturing images of the environment surrounding the autonomous vehicle. The camera 211 may be a camera and / or a video camera. The camera can be moved mechanically, for example, by mounting it on a rotating and / or tilting platform.

[0037] Sensor system 115 may also include other sensors, such as sonar sensors, infrared sensors, steering sensors, throttle sensors, brake sensors, and audio sensors (e.g., microphones). Audio sensors can be used to capture sound from the environment surrounding the autonomous vehicle. Steering sensors can be used to sense the steering angle of the steering wheel, wheels, or a combination thereof. Throttle and brake sensors sense the throttle and brake positions of the vehicle, respectively. In some cases, the throttle and brake sensors can be integrated into an integrated throttle / brake sensor.

[0038] In one embodiment, the vehicle control system 111 includes, but is not limited to, a steering unit 201, an acceleration unit 202, and a braking unit 203. The steering unit 201 is used to adjust the direction or heading of the vehicle. The acceleration unit 202 is used to control the speed of a motor or engine, thereby controlling the speed and acceleration of the vehicle. The steering unit 201 and the acceleration unit 202 may be partially integrated with… Figure 5 The AD controller 510 is coupled to the braking unit 203, which decelerates the vehicle by providing friction to the wheels or tires. The braking unit 203 may be partially coupled to... Figure 5 The braking control is coupled to 520. It should be noted that... Figure 2 The components shown can be implemented as hardware, software, or a combination thereof.

[0039] See you again Figure 1 The wireless communication system 112 allows the autonomous vehicle 101 to communicate with external systems, such as devices, sensors, and other vehicles. For example, the wireless communication system 112 can communicate directly with one or more devices, or via a communication network such as servers 103-104 on network 102. The wireless communication system 112 can utilize any cellular communication network or wireless local area network (WLAN), such as WiFi, to communicate with another component or system. The wireless communication system 112 can communicate directly with devices (e.g., mobile devices of passengers within vehicle 101, display devices, speakers), for example, using infrared links, Bluetooth, etc. The user interface system 113 may be some peripheral devices implemented within vehicle 101, including, for example, a keyboard, touchscreen display, microphone, and speaker.

[0040] Some or all of the functions of the autonomous vehicle 101 can be controlled or managed by the autonomous driving system 110, especially when operating in autonomous driving mode. The autonomous driving system 110 includes the necessary hardware (e.g., processor, memory, storage) and software (e.g., operating system, planning and route selection program) to receive information from the sensor system 115, control system 111, wireless communication system 112, and / or user interface system 113, process the received information, plan a route or path from the origin to the destination, and then drive the vehicle 101 based on the planning and control information. Alternatively, the autonomous driving system 110 can be integrated with the vehicle control system 111.

[0041] For example, a passenger can specify the start and destination of their trip via a user interface. The autonomous driving system 110 obtains trip-related data. For instance, the autonomous driving system 110 can obtain location and route data from a map and point-of-interest (POI) server, which may be part of servers 103-104. The location server provides location services, and the map and POI server provides map services and points of interest for some locations. Alternatively, this location, map, and POI information can be cached locally in the persistent storage of the autonomous driving system 110.

[0042] As the autonomous vehicle 101 moves along the route, the autonomous driving system 110 can also obtain real-time traffic information from a Traffic Information System or Server (TIS). It should be noted that servers 103-104 can be operated by a third-party entity. Alternatively, the functions of servers 103-104 can be integrated into the autonomous driving system 110. Based on real-time traffic information, map and point-of-interest information, location information, and real-time local environmental data (such as obstacles, objects, and nearby vehicles) detected or sensed by the sensor system 115, the autonomous driving system 110 can, for example, plan the optimal route according to the planned route via the control system 111 and drive the vehicle 101 to safely and efficiently reach the designated destination.

[0043] Figure 3 This is a block diagram illustrating an example of an AD system for an autonomous vehicle. System 300 can be implemented as follows: Figure 1 This is part of the autonomous vehicle 101, including but not limited to the autonomous driving system 110, the control system 111, and the sensor system 115. See also Figure 3 The autonomous driving system 110 includes, but is not limited to, a positioning module 301, a perception module 302, a prediction module 303, a decision-making module 304, a planning module 305, a control module 306, a route module 307, and a braking control module 308.

[0044] Some or all of modules 301-308 can be implemented as software, hardware, or a combination thereof. For example, these modules can be installed in persistent storage device 352, loaded into memory 351, and executed by one or more processors (not shown). It should be noted that some or all of these modules can be integrated with… Figure 2 Some or all of the modules of the vehicle control system 111 are communicatively coupled or integrated together. Some of the modules in modules 301 to 308 can be integrated into an integrated module.

[0045] The positioning module 301 determines the current location of the autonomous vehicle 300 (e.g., using the GPS module 212) and manages any data related to the user's trip or route. The positioning module 301 (also called the map and route module) manages any data related to the user's trip or route. The user can log in, for example, through a user interface and specify the start and destination of the trip. The positioning module 301 communicates with other components of the autonomous vehicle 300, such as map and route data 311, to obtain trip-related data. For example, the positioning module 301 can obtain location and route data from a location server and a map and point-of-interest (POI) server. The location server provides location services, and the map and POI server provides map services and points of interest for some locations, which can be cached as part of the map and route data 311. As the autonomous vehicle 300 moves along the route, the positioning module 301 can also obtain real-time traffic information from a traffic information system or server.

[0046] The perception module 302 can determine the perceived information of the surrounding environment based on the sensor data provided by the sensor system 115 and the positioning information obtained by the positioning module 301. The perceived information can represent information about the vehicle's surroundings that a normal driver can perceive while driving. The perceived information may include, for example, lane configurations in the form of objects, traffic light signals, the relative positions of other vehicles, pedestrians, buildings, crosswalks, or other traffic-related signs (e.g., stop signs, yield signs). Lane configurations include information describing one or more lanes, such as lane shape (e.g., straight or curved), lane width, number of lanes on the road, one-way or two-way lanes, merging or dividing lanes, lane departure, etc.

[0047] The perception module 302 may include a computer vision system or the functionality of a computer vision system to process and analyze images captured by one or more cameras to identify objects and / or features in the environment of the autonomous vehicle. Objects may include traffic signals, road boundaries, other vehicles, pedestrians and / or obstacles, etc. The computer vision system may utilize object recognition algorithms, video tracking, and other computer vision techniques. In some embodiments, the computer vision system may map the environment, track objects, and estimate the velocity of objects, etc. The perception module 302 may also detect objects based on additional sensor data provided by other sensors such as radar and / or lidar.

[0048] For each object, prediction module 303 predicts the object's behavior in the environment. This prediction is performed based on perception data, which senses the driving environment at a given point in time based on a set of map / route information 311 and traffic rules 312. For example, if the object is a vehicle traveling in the opposite direction and the current driving environment includes an intersection, prediction module 303 will predict that the vehicle is likely to go straight or turn. If the perception data indicates that there are no traffic lights at the intersection, prediction module 303 can predict that the vehicle must come to a complete stop before entering the intersection. If the perception data indicates that the vehicle is currently in a dedicated left-turn lane or a dedicated right-turn lane, prediction module 303 can predict that the vehicle is more likely to turn left or right, respectively.

[0049] For each object, decision module 304 makes a decision related to the object. For example, for a specific object (e.g., another vehicle at an intersection) and its metadata describing that object (e.g., speed, direction, turning angle), decision module 304 decides how to deal with the object (e.g., overtake, yield, stop, pass). Decision module 304 can make these decisions based on a set of rules, such as traffic rules or driving rules 312, which can be stored in persistent storage device 352. Persistent storage device 352 may include braking hysteresis reference 313.

[0050] The route module 307 is used to provide one or more routes or paths from a starting point to a destination. For a given trip from a starting location to a destination location, such as received from a user, the route module 307 obtains route and map information 311 and determines all possible routes or paths from the starting location to the destination location. The route module 307 can generate a reference line in the form of a topographic map for each route it determines from the starting location to the destination location. The reference line refers to the ideal route or path under conditions of no interference such as other vehicles, obstacles, or traffic conditions. That is, if there are no other vehicles, pedestrians, or obstacles on the road, the autonomous vehicle should follow the reference line exactly or approximately.

[0051] The terrain map is then provided to the decision module 304 and / or the planning module 305. The decision module 304 and / or the planning module 305 can examine all possible routes to select and modify one of the optimal routes based on other data provided by other modules, such as traffic conditions from the positioning module 301, the driving environment perceived by the perception module 302, and the traffic conditions predicted by the prediction module 303. The actual path or route used to control the autonomous vehicle may approximate or differ from the reference line provided by the route module 307, depending on the specific driving environment at that point in time.

[0052] The planning module 305 can plan the path or route of the autonomous vehicle and driving parameters (such as distance, speed, and / or turning angle) based on the decisions made for each perceived object and using reference lines provided by the route module 307. That is, for a given object, the decision module 304 decides what to do for that object, while the planning module 305 decides how to do it. For example, for a given object, the decision module 304 may decide to pass through the object, while the planning module 305 may determine whether to pass from the left or right side of the object. The planning module 305 generates planning and control data, including information describing how the vehicle 101 will move in the next movement cycle (e.g., the next route / path segment). For example, the planning and control data may instruct the vehicle 101 to move 10 meters at a speed of 30 miles per hour (mph) and then change to the right lane at a speed of 25 miles per hour.

[0053] Control module 306 controls and drives the autonomous vehicle based on planning and control data, according to a route or path defined by planning and control information, by sending appropriate commands or signals to vehicle control system 111. The planning and control data includes sufficient information to drive the vehicle from one point to another along the route or path at different times using appropriate vehicle settings or driving parameters (e.g., throttle, braking, steering commands).

[0054] In one embodiment, the planning phase is executed over multiple planning cycles, also known as driving cycles, for example, time intervals of 100 milliseconds (ms). For each planning cycle or driving cycle, one or more control commands can be issued based on the planning and control data. That is, for every 100 milliseconds, the planning module 305 plans, for example, the next route segment or path segment including the target location and the time required for the autonomous vehicle to reach the target location. Alternatively, the planning module 305 may also specify specific speeds, directions, and / or steering angles, etc. In one embodiment, the planning module 305 plans, for example, the next predetermined time interval of 5 seconds. For each planning cycle, the planning module 305 plans the target location for the current cycle (e.g., the next 5 seconds) based on the target location planned in the previous cycle. Subsequently, the control module 306 generates one or more control commands (e.g., throttle, brake, steering control commands) based on the planning and control data of the current cycle.

[0055] It is important to note that the decision-making module 304 and the planning module 305 can be integrated into a single module. The decision-making module 304 / planning module 305 may include a navigation system or the functionality of a navigation system to determine the driving path of the autonomous vehicle. For example, the navigation system may determine a series of speeds and directional headings, causing the autonomous vehicle to move along a path that substantially avoids perceived obstacles, while also typically guiding the autonomous vehicle along a lane-based path leading to the final destination. The destination can be set via user interface system 113 based on user input. The navigation system can dynamically update the driving path while the autonomous vehicle is in operation. The navigation system can combine data from a GPS system and one or more maps to determine the driving path of the autonomous vehicle.

[0056] Figure 3 The braking control module 308 can be connected with Figure 5 The braking control 520 is similar (or functionally equivalent) to that of the 520, used for controlling... Figure 4 Example braking system 400. Figure 4 This is a block diagram illustrating an example of a braking system 400 according to various aspects of this disclosure. Figure 4 As shown, the braking system 400 includes at least a mechanism for receiving brake actuation from the driver, a device for providing brake assist (e.g., a booster), a cylinder for pressurizing brake fluid (e.g., a master cylinder), an electric motor on the master cylinder, one or more brake lines carrying brake fluid, and one or more brakes on the vehicle rotor for transmitting braking power. The braking system 400 may also include a power source independent of or shared with the vehicle. The braking system 400 may include AD control (e.g., AD). Figure 5The AD controller 510 or connected to an AD controller, which operates the above-mentioned components / equipment through sensor feedback.

[0057] The device providing brake assist and the electric motor on the master cylinder are shown separately, but they can be integrated into a common device. For example, the driver's brake actuation can provide direct actuation to the electric motor on the master cylinder. In other embodiments, the brake assist device can be a separate or independent (e.g., hydraulic) system for secondary control of the master cylinder, such as emergency engagement by the driver when AD control does not operate as expected. As described herein, when the vehicle is road-testing on a slope, the brake control module 308 can reduce the power consumption of the electric motor on the master cylinder to conserve energy.

[0058] Figure 5 This is a block diagram 500 illustrating the implementation of AD control 510 and braking control 520 according to various aspects of this disclosure. As shown, AD control 510 includes an automated driving or driver assistance (AD) computing system 532, vehicle deceleration control 534, and pressure request control 536. AD computing system 532 can, for example, consider traffic and / or road conditions (e.g., obstacles) to identify situations requiring active vehicle deceleration. Active deceleration can include braking using a braking system and deceleration by converting kinetic energy into electrical energy (while passive deceleration can include deceleration caused by friction and aerodynamic drag). Vehicle deceleration control 534 can determine a response (e.g., confirming an appropriate deceleration mode) based on available travel distance and time to employ one or more deceleration methods.

[0059] When vehicle deceleration control 534 determines that the braking system needs to be activated to decelerate the vehicle, vehicle deceleration control 532 can provide the required deceleration rate to pressure request control 536, which then activates braking control 520 via pressure and torque commands. In some cases, such as when the vehicle is in low torque hold mode, AD driving calculation system 532 can communicate directly with pressure request control 536 without requiring data processing by vehicle deceleration control 534.

[0060] Braking control 520 receives pressure and torque commands from AD control 510 and executes these commands in the braking system. As shown, braking control 520 includes brake stroke control 542, motor torque control 544, motor device control 546, and a motor 548 for the brake actuation system (e.g., the braking system). Braking stroke control 542 can convert pressure commands (e.g., pressure applied by the driver and amplified by the brake booster) into hydraulic pressure in the stroke of the tandem master cylinder (TMC). Motor torque control 544 receives the hydraulic pressure and calculates the corresponding motor torque required by motor 548. Motor device control 546 then converts the required motor torque into motor current and / or pulse width modulation (PWM) voltage signals for motor 548.

[0061] According to various aspects of this disclosure, based on the hysteresis characteristics of the braking system, energy savings can be achieved by reducing the actual current or energy consumption at motor 548 without sacrificing braking torque output at the brake. The reduction in current can be controlled at various points in block diagram 500, such as pressure request control 536. For example, pressure request control 536 may include or access the braking hysteresis characteristics of the braking system and determine the pressure value of brake stroke control 542 in a pressure reduction command and / or determine the torque of motor torque reduction control 544 (e.g., by providing a correction value / delta value). An example of the braking hysteresis characteristics of the braking system is as follows: Figure 6 As shown, it will be described below.

[0062] Figure 6 An example application of braking hysteresis, according to various aspects of this disclosure, for reducing power consumption in a braking system is shown. For example... Figure 6 As illustrated in the hysteresis example, increasing and decreasing brake pressure results in different braking torque responses. In other words, the same braking torque output can be achieved under two different brake pressure input values. This difference leads to reduced braking torque. Figure 5 The power consumption of the Zhongdian 548 provides room for improvement.

[0063] like Figure 6As shown, a vehicle (such as an ADV) can be parked on a slope (e.g., with a positive or negative gradient) during a road test. In this case, even when the vehicle has come to a complete stop, the braking system continues to operate, with the braking torque offsetting the gravitational component along the slope. For ease of illustration, assume that a braking pressure of 6 megapascals (MPa) is required to safely keep the vehicle stationary on the slope, generating an initial braking torque of 0.85 Nm, provided by an electric motor at 21 A. However, due to braking hysteresis characteristics, the braking torque can be reduced to 0.5 Nm, provided by the electric motor at 10 A, while maintaining the braking pressure at 6 MPa. By reducing the current at the motor, significant power can be saved. Therefore, a significant voltage drop at the power source (e.g., a DC battery) can be reduced or prevented.

[0064] Figure 7 This is a flowchart illustrating a current reduction method in a braking system according to various aspects of this disclosure. The method can be handled by processing logic (e.g., with...). Figure 5 The pressure request control (related to 536) is executed, and this logic may include software, hardware, or a combination thereof. For example, the method shown in flowchart 700 may be executed by... Figure 3 The braking control module 308 executes the commands.

[0065] In operation 710, after the vehicle stops moving on the slope, the brake control module (e.g., the processing unit) applies a first current (e.g., ...) to the vehicle's braking system. Figure 6 (As shown in 21A). The first current prevents the vehicle from moving on a slope by generating braking pressure sufficient to counteract gravity or engine idling force. In some cases, the braking control module can determine that the vehicle is on a slope based on at least one of map information, sensor information, or braking system feedback, through communication with other operating devices or modules in the vehicle. For example, when the braking pressure decreases, the braking control module can determine that the vehicle is on a slope based on feedback from the braking system by monitoring the movement (and rate) of the rotor.

[0066] In operation 720, the braking control module determines the first braking pressure based on the first current and the ramp (e.g., Figure 6 (e.g., 6 MPa as shown). For example, the first current can correspond to the braking actuation, which generates a directly measurable pressure value or a pressure value corresponding to the current in a lookup table. The braking pressure can also correspond to the gravitational component calculated based on the vehicle's mass and the gradient, which can be used to directly or indirectly verify the pressure value obtained from the first current.

[0067] In operation 730, the braking control module determines a second current (e.g., based on a first braking pressure (e.g., 6 MPa) and braking hysteresis) Figure 6(e.g., 10A as shown). The second current is lower than the first current. In some embodiments, determining the second current may include looking up the braking hysteresis in a lookup table consisting of values ​​of braking pressure and torque measured at multiple brakes of the braking system. The braking pressure values ​​correspond to the variable current input of the braking system. Different current inputs can result in different braking torques, thus producing the braking hysteresis characteristic.

[0068] Because the second current is less than the first current, in operation 740, the brake control module can reduce the first current in the braking system to the second current to achieve energy savings. In some cases, the brake pressure and torque values ​​(and corresponding currents) measured based on the mapped brake hysteresis characteristics are evaluated according to a safety factor in a lookup table, such that the second current is greater than the current corresponding to the same brake pressure in the actual brake hysteresis. The AD control (e.g., pressure request control 536 of AD control 510) or the brake control module (e.g., brake control 520) can obtain the brake hysteresis through one of the various methods described below.

[0069] In some embodiments, the braking control module utilizes a second current to prevent the voltage of the vehicle's power system from dropping below a threshold. The braking control module can also store the electrical energy saved by reducing the first current to the second current for use during large current surges (e.g., for engine restarting after a road check).

[0070] Figure 8 This is a flowchart 800 illustrating a method for obtaining a braking hysteresis reference of a braking system according to various aspects of this disclosure. In some cases, the method may be provided by processing logic (e.g., Figure 5 The AD control 510) executes the processing logic, which may include software, hardware, or a combination thereof. In some cases, the method shown in flowchart 800 can be performed by... Figure 3 Braking control module 308 or Figure 9 The delay determination module 910 is executed.

[0071] In operation 810, the braking control module can initialize the characterization process at one of several selected slopes. The selected slope can provide a known gradient, allowing for accurate determination of the vehicle's gravity component. Initialization may also include driving the vehicle at a constant speed, which is set for the characterization process.

[0072] During operation 820, the brake control module can apply braking pressure and monitor the vehicle's braking response. For example, the braking response may include data on vehicle deceleration. The input braking pressure can be recorded to verify the measured actual braking pressure.

[0073] In operation 830, the brake control module can measure multiple different brake pressures and corresponding current values. These multiple pressure and current values ​​provide data to depict at least a portion of the brake hysteresis, such as the portion where an increase in current leads to an increase in brake pressure.

[0074] During operation 840, the brake control module can reduce the current and the corresponding braking torque, and monitor the slippage of the braking system (e.g., when the rotor begins to move relative to the brake pads).

[0075] During operation 850, when brake system slippage is first detected, for example, on one of several selected ramps, the brake control module can measure the brake pressure and the corresponding current value. Measurements may include interpolations of current and brake pressure that are not directly measured.

[0076] In operation 860, the brake control module can compile values ​​for hysteresis trends (e.g., by plotting brake pressure and brake torque values).

[0077] In operation 870, the braking control module can formalize the braking hysteresis prediction for use in driving control. For example, the braking control module can employ one or more statistical analysis methods to remove noise or outliers from the measurements. The braking control module can also process the braking hysteresis into specific units suitable for the control algorithm. In some cases, the braking control module can use a safety factor when formalizing the braking hysteresis to save computation in subsequent operations.

[0078] Figure 9 This is a block diagram 900 illustrating the operation of the hysteresis determination module 910 according to various aspects of this disclosure. As described above, the hysteresis determination module 910 can perform the method shown in flowchart 800 by monitoring and measuring braking pressure, torque, and current used to compile braking hysteresis characteristics. In some cases, the hysteresis determination module 910 can verify or update braking hysteresis in routine operation (e.g., instead of dedicated calibration operation).

[0079] During operation, the hysteresis determination module can first move the brake actuator to its home position (e.g., the initial position), where the braking pressure is zero. Then, the hysteresis determination module can receive an initial pressure request, such as 5 MPa, and accordingly actuate the brake actuator to engage the braking system. When the motor stops at a position where the braking pressure and braking torque are balanced, the torque measurement and current value are recorded.

[0080] As described above, the hysteresis determination module can (e.g., based on signals from pulse sensors, by detecting changes in wheel position) reduce the motor torque until the actuator system begins to cause the vehicle to slip. Slippage can also be indicated by any changes in motor position, motor electronic angle, or by transients of characteristic method (TMOC) pressure. For different braking pressure values, torque measurements (e.g., motor torque) and corresponding current values ​​(e.g., effective motor current) at the time of slippage are recorded.

[0081] Figure 10 Example 1000 of determining braking hysteresis characteristics according to various aspects of this disclosure is shown. In example 1000, discrete values ​​of braking torque and braking pressure are measured to infer braking hysteresis characteristics (e.g., within the range of interest). Figure 10 As shown, the vehicle can measure the initial braking pressure (P1) on a slope with a known gradient. The corresponding braking torque (N1) is then measured to obtain data points (P1, N1).

[0082] The vehicle then reduces the braking torque to N2, causing the brake motor to slip, allowing a second data point (P1, N2) to be recorded. Similarly, a second braking pressure (P2) can be applied to obtain data points (P2, N3) and (P2, N4). The braking hysteresis curve can then be approximated by plotting lines from (P1, N1) to (P2, N3) and from (P1, N2) to (P2, N4). The approximate braking characteristics can be further modified using a safety factor. In some cases, the approximate braking characteristics can be used in the vehicle's low-torque operating mode.

[0083] Figure 11 Example 1100 of determining braking hysteresis characteristics according to various aspects of this disclosure is shown. Example 1100 differs from Example 1000 in that the braking hysteresis characteristics can be verified or updated during operation. In addition to measuring (P1, N1) and (P1, N2) as described above, (P10, N11) can also be measured during acceleration when the engine output torque is greater than zero. The braking hysteresis characteristics can be applied to a low-torque mode, in which braking power is transferred from the braking system to the vehicle's engine system. For example, when the vehicle stops on a positive slope, the engine torque output can take over from the braking system, thereby preventing the vehicle from moving backward. The engine torque can be converted into braking pressure P10 in the following manner:

[0084] (Engine torque - (Mgsin(θ) - Mgcos(θ) * f) * K2) / K1 = pressure (P10), where f is the coefficient of friction; K2 is a constant used to convert the force value into the torque value; and K1 is a constant used to convert the torque value into the braking pressure.

[0085] In this way, the vehicle can utilize different engine torque values ​​to obtain different braking pressure values, thereby compiling braking hysteresis characteristics. The application of low torque mode will be combined with the following... Figure 12 and Figure 13 Further description.

[0086] Figure 12 This is a flowchart 1200 illustrating an application method for braking hysteresis characteristics during operation according to various aspects of this disclosure. The method is applicable to hybrid or internal combustion engine vehicles, wherein the engine can be shut off during a road test and restarted at the end of the road test. The method can be comprised of processing logic (e.g., Figure 5 The AD control is executed by [the system / mechanism], and this logic may include software, hardware, or a combination thereof. For example, the method shown in flowchart 1200 can be [executed by] [the system / mechanism]. Figure 3 The control module 306 executes.

[0087] In operation 1210, the control module, for example, slows the vehicle to a complete stop by applying the braking system, stopping the vehicle on a slope.

[0088] In operation 1220, the control module uses the main braking system (PBS) to keep the vehicle under a gradient-based braking pressure.

[0089] During operation 1230, the control module determines whether to request low torque mode. For example... Figure 11 As shown, the low torque mode allows the vehicle to convert braking power from the braking system into engine power to keep the vehicle stationary on a slope with a positive gradient. If the low torque mode is requested, in operation 1240, the control module requests the PBS to keep the vehicle in low torque mode by using a first calculated torque.

[0090] In operation 1250, the control module determines whether to request engine turning and low torque mode. When engine turning is not requested, the control module continues to hold the vehicle using the PBS at a first calculated torque. When engine turning is requested, in operation 1260, the control module requests the PBS to hold the vehicle at a second calculated torque (e.g., based on reduced current input). Thus, the electrical energy saved at the second calculated torque can facilitate engine turning (e.g., by reducing the amount of voltage drop and providing sufficient turning current). An example of preventing voltage drop using the method in flowchart 1200 is as follows... Figure 13 As shown.

[0091] Figure 13 The following are shown in accordance with various aspects of this disclosure Figure 12The example timeline 1300 shows engine torque and battery voltage for the example method illustrated. As shown, a significant drop in battery voltage can occur during engine restart and engine turning. The corresponding engine output torque will also decrease accordingly. Therefore, by reducing the current consumption of the braking system during engine restart and / or engine turning operations, a significant drop in battery voltage is avoided.

[0092] Figure 14 An example 1400 of a power switching method for implementing braking hysteresis characteristics according to various aspects of this disclosure is shown. As shown, a power switching operation can cause a power switch between a main power supply 1410 and a secondary power supply 1420. The power switching decision allows for real-time determination of braking hysteresis characteristics. For example, the hysteresis determination module 910 can adjust the current to reduce braking torque to detect when slippage occurs. Such real-time driving characteristics are unsafe if slippage would cause the vehicle to move significantly. Figure 14 The power switching decision module can utilize either the main power supply 1410 or the secondary power supply 1420 as a backup energy source to immediately increase the current to increase braking torque when slippage is detected. This is separate from the current reduction control. For example, when the vehicle state has changed and braking intervention is indicated, the alternative power supply can be switched on to bypass the hysteresis determination module 910 to ensure operational safety.

[0093] It should be noted that some or all of the components shown and described above may be implemented by software, hardware, or a combination thereof. For example, these components may be implemented as software installed and stored in persistent storage, which may be loaded into memory and executed by a processor (not shown) to perform the processes or operations described herein. Alternatively, these components may be implemented as executable code programmed or embedded in dedicated hardware, such as integrated circuits (e.g., application-specific integrated circuits or ASICs), digital signal processors (DSPs), or field-programmable gate arrays (FPGAs), which may be accessed from an application via appropriate drivers and / or operating systems. Furthermore, these components may be implemented as specific hardware logic within a processor or processor core as part of an instruction set accessible by software components via one or more specific instructions.

[0094] Some parts of the foregoing detailed description have been introduced based on algorithms and symbolic representations for manipulating data bits in computer memory. These algorithmic descriptions and representations are the means by which those skilled in the art of data processing most effectively communicate the substance of their work to others skilled in the art. In this paper, algorithms are generally considered to be self-consistent sequences of operations that lead to desired results. These operations refer to those that require physical manipulation of physical quantities.

[0095] However, it should be remembered that all these terms and similar terms will be associated with appropriate physical quantities and are merely convenient notations applied to those quantities. Unless explicitly stated in the above discussion, it should be understood that throughout the specification, the use of terms such as those set forth in the appended claims refers to the operation and processing of a computer system or similar electronic computing device that manipulates data represented as physical (electronic) quantities in computer system registers and memories, and transforms that data into other data similarly represented as physical quantities in computer system memories or registers or other such information storage devices, transmission devices or display devices.

[0096] Embodiments of this disclosure also relate to means for performing the operations described herein. Such a computer program is stored in a non-transitory computer-readable medium. Machine-readable media include any mechanism for storing information in a machine-readable (e.g., computer-readable) form. For example, machine-readable (e.g., computer-readable) media include machine-readable (e.g., computer-readable) storage media (e.g., read-only memory (“ROM”), random access memory (“RAM”), disk storage media, optical storage media, flash memory devices).

[0097] The processes or methods depicted in the foregoing figures can be executed by processing logic, which includes hardware (e.g., circuits, special-purpose logic, etc.), software (e.g., embodied in a non-transitory computer-readable medium), or a combination of both. Although the process or method has been described above according to some sequential operations, it should be understood that some of the described operations can be performed in a different order. Furthermore, some operations can be performed in parallel rather than sequentially.

[0098] The embodiments disclosed herein are not described with reference to any particular programming language. It should be understood that the teachings of the embodiments of this disclosure as described herein can be implemented using a variety of programming languages.

[0099] In the foregoing description, embodiments of the present disclosure have been described with reference to specific exemplary embodiments. It is obvious that various modifications can be made to the present disclosure without departing from the broader spirit and scope of the disclosure as set forth in the appended claims. Therefore, the description and drawings should be regarded as illustrative rather than restrictive.

Claims

1. A computer-implemented method for reducing the current during vehicle braking to save power, the method comprising: After the vehicle stops moving on the slope, a first current is applied to the vehicle's braking system to prevent the vehicle from moving on the slope. The first braking pressure is determined based on the first current and the ramp. The second current is determined based on the first braking pressure and braking hysteresis, wherein the second current is lower than the first current; as well as Reduce the first current in the braking system to the second current; Determining the second current based on the first braking pressure and the braking hysteresis includes: The braking hysteresis is found in a lookup table, which includes braking pressure and torque values ​​measured at multiple brakes of the braking system, wherein the braking pressure value corresponds to the variable current input of the braking system. Based on the first current, the required torque value is found in the lookup table; and Based on the required torque value, the second current is determined in the lookup table.

2. The computer-implemented method according to claim 1 further includes: The vehicle is determined to be on the slope based on at least one of map information, sensor information, or feedback from the braking system.

3. The computer-implemented method according to claim 1, wherein, The measured braking pressure and torque values ​​are determined based on the safety factor in the lookup table.

4. The computer-implemented method according to claim 1, wherein, Determining the second current based on the first braking pressure and the braking hysteresis further includes: When the first current is applied, the first braking pressure in the braking system is monitored; When the vehicle stops moving on the slope, the first braking torque is recorded; Reduce the first braking pressure of the vehicle to restore driving; When the vehicle begins to move, the second braking pressure in the braking system is monitored and the second braking torque is recorded. The braking hysteresis is verified or updated based on the first braking pressure, the first braking torque, the second braking pressure, and the second braking torque; and The second current is determined based on the verified or updated braking hysteresis and the second braking torque.

5. The computer-implemented method according to claim 1, wherein, Determining the second current based on the first braking pressure and the braking hysteresis further includes: Measure the output torque of the vehicle's engine or motor; Measure the slope of the slope; The required braking torque is calculated based on the output torque and the slope; and The second current is determined based on the required braking torque and the braking hysteresis.

6. The computer-implemented method according to claim 1, further comprising at least one of the following steps: To prevent the voltage of the vehicle's electrical system from dropping below a threshold; or The electrical energy saved by reducing the first current to the second current is stored for use during high current surges.

7. A computing device, comprising: Memory, which stores executable instructions; as well as A processing device coupled to the memory, the processing device being configured to execute the executable instructions to perform the following operations: After the vehicle stops moving on the slope, a first current is applied to the vehicle's braking system to prevent the vehicle from moving on the slope. The first braking pressure is determined based on the first current and the ramp. The second current is determined based on the first braking pressure and braking hysteresis, wherein the second current is lower than the first current; as well as Reduce the first current in the braking system to the second current; The processing device determines the second current based on the first braking pressure and the braking hysteresis, including: The braking hysteresis is found in a lookup table, which includes braking pressure and torque values ​​measured at multiple brakes of the braking system, wherein the braking pressure value corresponds to the variable current input of the braking system. Based on the first current, the required torque value is found in the lookup table; and Based on the required torque value, the second current is determined in the lookup table.

8. The computing device according to claim 7, wherein, The processing device is also configured to execute the executable instructions in order to perform the following operations: The vehicle is determined to be on the slope based on at least one of map information, sensor information, or feedback from the braking system.

9. The computing device according to claim 7, wherein, The measured braking pressure and torque values ​​are determined based on the safety factor in the lookup table.

10. The computing device according to claim 7, wherein, The processing device further includes determining the second current based on the first braking pressure and the braking hysteresis: When the first current is applied, the first braking pressure in the braking system is monitored; When the vehicle stops moving on the slope, the first braking torque is recorded; Reduce the first braking pressure of the vehicle to restore driving; When the vehicle begins to move, the second braking pressure in the braking system is monitored and the second braking torque is recorded. The braking hysteresis is verified or updated based on the first braking pressure, the first braking torque, the second braking pressure, and the second braking torque; and The second current is determined based on the verified or updated braking hysteresis and the second braking torque.

11. The computing device according to claim 7, wherein, The processing device further includes determining the second current based on the first braking pressure and the braking hysteresis: Measure the output torque of the vehicle's engine or motor; Measure the slope of the slope; The required braking torque is calculated based on the output torque and the slope; and The second current is determined based on the required braking torque and the braking hysteresis.

12. The computing device according to claim 7, wherein, The processing device is also configured to perform at least one of the following steps: To prevent the voltage of the vehicle's electrical system from dropping below a threshold; or The electrical energy saved by reducing the first current to the second current is stored for use during high current surges.

13. A non-transitory computer-readable medium storing instructions that, when executed by a processing device, cause the processing device to perform the following operations: After the vehicle stops moving on the slope, a first current is applied to the vehicle's braking system to prevent the vehicle from moving on the slope. The first braking pressure is determined based on the first current and the ramp. The second current is determined based on the first braking pressure and braking hysteresis, wherein the second current is lower than the first current; as well as Reduce the first current in the braking system to the second current; Determining the second current based on the first braking pressure and the braking hysteresis includes: The braking hysteresis is found in a lookup table, which includes braking pressure and torque values ​​measured at multiple brakes of the braking system, wherein the braking pressure value corresponds to the variable current input of the braking system. Based on the first current, the required torque value is found in the lookup table; and Based on the required torque value, the second current is determined in the lookup table.

14. The non-transitory computer-readable medium of claim 13, further comprising instructions for causing the processing apparatus to perform the following operations: The vehicle is determined to be on the slope based on at least one of map information, sensor information, or feedback from the braking system.

15. The non-transitory computer-readable medium according to claim 13, wherein, The measured braking pressure and torque values ​​are determined based on the safety factor in the lookup table.

16. The non-transitory computer-readable medium according to claim 13, wherein, Determining the second current based on the first braking pressure and the braking hysteresis further includes: When the first current is applied, the first braking pressure in the braking system is monitored; When the vehicle stops moving on the slope, the first braking torque is recorded; Reduce the first braking pressure of the vehicle to restore driving; When the vehicle begins to move, the second braking pressure in the braking system is monitored and the second braking torque is recorded. The braking hysteresis is verified or updated based on the first braking pressure, the first braking torque, the second braking pressure, and the second braking torque; and The second current is determined based on the verified or updated braking hysteresis and the second braking torque.

17. The non-transitory computer-readable medium according to claim 13, wherein, Determining the second current based on the first braking pressure and the braking hysteresis further includes: Measure the output torque of the vehicle's engine or motor; Measure the slope of the slope; The required braking torque is calculated based on the output torque and the slope; and The second current is determined based on the required braking torque and the braking hysteresis.

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