VEHICLE WITH A FAULT-TOLERANT ELECTRONIC BRAKE-BY-WIRE (BBW) SYSTEM AND METHOD FOR CONTROLLING SUCH A BBW SYSTEM

Abstract

Vehicle (100) with a fault-tolerant electronic brake-by-wire (BBW) system (102), the vehicle (100) comprising: a plurality of braking systems (118a, 118b, 118c, 118d) configured to control the braking of a respective wheel of the vehicle (100), the plurality of braking systems (118a, 118b, 118c, 118d) comprising: a first braking system (118a) integrated with an intelligent actuator unit (203a) comprising a first actuator controller (201a) and a first electromechanical actuator (120a) configured to adjust a braking force applied to a first wheel (112a) coupled to the first braking system (118a); a second braking system (118b) excluding actuator control and having installed therein a second electromechanical actuator (120b) configured to adjust a braking force applied to a second wheel (112b) coupled to the second braking system (118b); and at least one electronic actuator driver unit (202a, 202b) remote from the first and second brake systems (118a, 118b) and configured to output a high power signal that drives the first and second electromechanical actuators (120a, 120b) in response to receiving a digital command signal from the first actuator controller (201a).

Description

FIELD OF THE INVENTION

[0001] The invention disclosed herein relates to vehicle braking systems and, more particularly, to a vehicle having a brake-by-wire (BBW) system and a method for controlling such a BBW system.

[0002] For background information, reference is made to DE 103 16 452 A1. This discloses a vehicle with a brake-by-wire (BBW) system, which includes a braking system configured to control the braking of a respective wheel of the vehicle. The braking system is integrated with an intelligent actuator unit, which includes a first actuator controller and a first electromechanical actuator configured to adjust a braking force applied to a first wheel coupled to the first braking system. BACKGROUND

[0003] Current automotive industry trends toward reducing the number of total mechanical components and overall vehicle weight have contributed to the development of system-by-wire applications, typically referred to as X-by-wire systems. One such X-by-wire system that has received more attention is a brake-by-wire (BBW) system, sometimes referred to as an electronic braking system (EBS).

[0004] Unlike conventional mechanical braking systems, BBW systems actuate one or more vehicle braking components via an electrical signal generated by an onboard processor / controller or received from a source external to the vehicle. In some systems, a BBW system is implemented by replacing a conventional hydraulic fluid-based service braking system with a base electric system to perform basic braking functions. Such a system is typically equipped with a manually operated backup system that can be hydraulically actuated.

[0005] Because BBW systems typically eliminate any direct mechanical connections and / or hydraulic power transmission paths between the vehicle operator and the brake control units, considerable attention has been paid to the design of BBW control systems and control architectures that ensure reliable and robust operation. Various design techniques have been implemented to promote BBW system reliability, including, for example, redundancy, fault tolerance to undesirable events (e.g., events affecting control signals, data, hardware, software, or other elements of such systems), fault monitoring, and recovery. A conventional design approach to providing fault tolerance used in BBW control systems has been to include a mechanical backup system that can be used as an alternative means of braking the vehicle.

[0006] The invention is based on the object of increasing the reliability of a BBW system without having to use a mechanical security system. SUMMARY

[0007] This object is achieved with a vehicle having the features of claim 1 or claim 9 and with a method having the features of claim 10.

[0008] According to one embodiment, a vehicle is provided having a plurality of braking systems configured to control the braking of a respective wheel of the vehicle. The braking systems include a first braking system integrated with an intelligent actuator unit including a first actuator controller and a first electromechanical actuator configured to adjust a braking force applied to a first wheel coupled to the first braking system. A second braking system excludes an actuator controller and has installed therein a second electromechanical actuator configured to adjust a braking force applied to a second wheel coupled to the second braking system.At least one electronic actuator driver unit is remotely located from the first and second brake systems and is configured to output a high power signal that drives the first and second electromechanical actuators in response to receiving a digital command signal from the first actuator controller.

[0009] According to another embodiment, a vehicle is provided that includes a fault-tolerant electronic brake-by-wire (BBW) system. The vehicle includes a plurality of brake systems configured to control the braking of a respective wheel of the vehicle. The plurality of brake systems includes a first group of brake systems and a second group of brake systems. The brake systems of the first group are each integrated with an electronic intelligent actuator unit that includes an electronic actuator controller and an electromechanical actuator. The brake systems of the second group each exclude an electronic actuator controller and have a built-in electromechanical slave actuator. The vehicle further includes first and second actuator driver units located remotely from the brake systems.Each of the first and second actuator driver units is in electrical communication with each electromechanical actuator of the first group and each electromechanical slave actuator of the second group.

[0010] According to another embodiment, a method for controlling a fault-tolerant electronic brake-by-wire (BBW) system comprises integrating a first intelligent actuator unit including a first electronic actuator controller and a first electromechanical actuator into a first intelligent braking system, and integrating a first electromechanical slave actuator excluding an electronic actuator controller into a first slave braking system. The method further comprises issuing a first digital command signal via the first electronic actuator controller that initiates a first actuator driver unit located remotely from the first intelligent braking system and the first slave braking system.In response to the first digital command signal, the first actuator driver unit outputs a high-power drive signal that controls braking of a first wheel coupled to the first brake system and braking of a second wheel coupled to the first slave brake system.

[0011] The above-mentioned features and advantages, as well as other features and advantages of the invention, are readily apparent from the following detailed description of the invention in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Other features and details appear only by way of example in the following detailed description of the embodiments and the detailed description, which refers to the following drawings, in which: Fig. 1 is a schematic plan view of a vehicle with a fault-tolerant BBW mechanism according to an embodiment; Fig. Figure 2 illustrates an intelligent actuator unit having an actuator controller in electrical communication with an electromechanical slave actuator; Fig. 3A is a schematic view of a fault-tolerant BBW system based on a split EBS control topology according to one non-limiting embodiment; Fig. 3B is a schematic view of a fault-tolerant BBW system based on a split EBS control topology, according to another non-limiting embodiment; Fig. 3C is a schematic view of a fault-tolerant BBW system based on a full EBS control topology according to a non-limiting embodiment; and Fig. 4 is a flowchart illustrating a method for controlling a fault-tolerant BBW system according to one non-limiting embodiment. DESCRIPTION OF THE EMBODIMENTS

[0013] The following description is for illustrative purposes only. Please note that the same reference numbers refer to the same or corresponding parts and features throughout the drawings.

[0014] Various embodiments provide a fault-tolerant BBW system including at least one smart brake system and at least one slave brake system. The smart brake system includes a smart brake actuator unit that integrates an electronic actuator controller and an electromechanical actuator, while the slave brake system excludes an actuator controller but still includes an electromechanical actuator, as understood by one skilled in the art. According to one embodiment, a first group of brake systems integrated with a smart actuator unit is referred to as the smart brake system, while a second group of brake systems that exclude an electronic actuator controller is referred to as the slave brake systems.

[0015] The BBW system further includes one or more actuator driver units located remotely (i.e., externally) from the smart brake system. In at least one embodiment where multiple actuator driver units are installed, each actuator driver unit is electrically connected to a respective actuator controller. Thus, each actuator controller outputs an individual digital command signal to a respective actuator driver unit. In response to receiving the digital command signal, the actuator driver unit outputs a high-power drive signal, such as a high-frequency, high-current switched signal, that drives the electromechanical actuator included in the smart brake system and the electromechanical slave actuator included in the slave brake system.In at least one embodiment, each actuator driver unit is capable of driving the electromechanical actuators in each intelligent braking system and each slave braking system. Locating the actuator driver units remotely (e.g., externally) from the braking systems exposes the actuator controller to lower levels of electromagnetic compatibility (EMC) (e.g., generation, propagation, and reception of electromagnetic energy). Actuator driver units are also known to generate excessive heat due to the high-power switching output signals. Therefore, locating the actuator driver units remotely from the braking systems also protects the actuator controllers and electromechanical actuators from excessive temperatures.

[0016] With reference to Fig. 1 illustrates a vehicle 100 having a fault-tolerant brake braking system 102 configured to electronically control braking of the vehicle 100, according to one embodiment. The vehicle 100 is propelled via a powertrain system including an engine 104, a transmission 108, and a transfer case 110. The engine 104 includes, for example, an internal combustion engine 104 configured to generate drive torque that drives the front wheels 112a and 112b and the rear wheels 114a and 114b using various vehicle driveline components. Various types of engines 104 may be used in the vehicle 100, including, but not limited to, a diesel engine, a gasoline engine, and a hybrid engine that combines an internal combustion engine with, for example, an electric motor.The fault-tolerant BBW system can also be implemented in a battery-powered electric vehicle with an electric motor without departing from the scope of the invention. The vehicle powertrain can be understood to include the various powertrain components, with the exception of the engine 104. According to one embodiment, the engine drive torque is transmitted to the transmission 108 via a rotatable crankshaft (not shown). Thus, the torque delivered to the transmission 108 can be adjusted in various ways, including, for example, by controlling the operation of the engine 104, as will be understood by those skilled in the art.

[0017] The fault-tolerant BBW system 102 includes a pedal assembly 116, brake systems 118a-118d (i.e., brake corner modules), one or more actuator units 120a-120d, one or more wheel sensors 122a and 122b, and an electronic braking system (EBS) controller 200. Although two wheel sensors 122a and 122b are shown, it should be understood that the number of wheel sensors may vary, e.g., four wheel sensors may be included. In at least one embodiment, the actuator units 120a-120d include one or more intelligent actuator units implemented with a single hardware controller and one or more electromechanical slave actuator units that exclude the hardware controller, as discussed in more detail herein. The actuator units 120a-120d and / or the sensors 122a-122b can communicate data with each other via a communication data bus.The data can be provided via a communication interface, including but not limited to FlexRay™, Ethernet, and a low-voltage message-based interface, such as a CAN (Controller Area Network) bus. FlexRay™ is a high-speed, fault-tolerant, time-triggered protocol with static and dynamic frames. FlexRay™ can support high data rates of up to 10 Mbps.

[0018] The pedal assembly 116 includes a brake pedal 124, a pedal force sensor 126, and a pedal travel sensor 128. The pedal assembly 116 may be any combination of hardware and software. For example, the pedal assembly 116 may be a pedal emulator that behaves like a depressible mechanical pedal of a hydraulic braking system. In at least one embodiment, the pedal assembly 116 may be operated solely by electronic circuitry and hardware computer processors to achieve vehicle braking, while omitting various mechanical and / or hydraulic components found in conventional pedal assemblies.

[0019] Brake pedal travel and / or braking force applied to brake pedal 124 may be determined based on respective signal outputs from pedal force sensor 126 and pedal travel sensor 128, as understood by one of ordinary skill in the art. According to an exemplary embodiment, pedal force sensor 126 is implemented as a force-to-pressure transducer or other suitable force sensor configured or adjusted to accurately detect, measure, or otherwise determine a pressure applied by an operator of vehicle 100 or a force transmitted to brake pedal 124. Pedal travel sensor 128 may be configured or adjusted as a pedal position and range sensor such that it precisely detects, measures, or otherwise determines the relative position and direction of travel of brake pedal 124 along a fixed range of travel when brake pedal 124 is depressed or applied.

[0020] The measurements or readings obtained by the pedal force sensor 126 and the pedal travel sensor 128 are transferable as required for use with one or more braking algorithms stored in the memory of an electronic controller. The data from the pedal force sensor 126 and / or the pedal travel sensor 128 may also be used to calculate, select, and / or otherwise determine an appropriate braking request or braking event in response to the sensed and recorded measurements or reading outputs from the wheel sensors 122a, 122b. Based on the determined braking request or braking event, the EBS controller 200 may execute various braking algorithms, speed calculations, distance-to-brake calculations, etc. Additionally, the EBS controller 200 may control various braking mechanisms or systems, such as an electronic emergency brake.

[0021] The wheel sensors 122a, 122b can provide various types of vehicle data, including, but not limited to, speed, acceleration, deceleration, vehicle angle relative to the surface, and wheel slip. In at least one embodiment, the fault-tolerant BBW system 102 can include one or more object detection sensors 129 located at various locations on the vehicle 100. The object detection sensors 129 are configured to detect the movement and / or existence of various objects surrounding the vehicle, including, but not limited to, surrounding vehicles, pedestrians, traffic signs, and roadway hazards. The object detection sensors 129 can provide data indicating a scenario (e.g., a requirement) to decelerate or stop the vehicle based on the vehicle speed, object proximity to the vehicle 100, etc.In response to determining the braking scenario, one or more braking systems 118a-118d may be controlled to decelerate or stop the vehicle 100, as discussed in more detail herein.

[0022] According to at least one embodiment, the fault-tolerant BBW system 102 may also include a separation module (not shown in Fig. 1) and one or more power sources (not shown in Fig. 1). The isolation module may be embodied as an electrical circuit and is configured to isolate circuit faults on a signaling line circuit (SLC). The isolation module also limits the number of modules or detectors that can be disabled by a circuit fault (e.g., short to ground, overvoltage, etc.) on the SLC loop. According to one embodiment, when a circuit fault occurs, the isolation module may automatically create an open (disconnect) in the SLC loop to isolate the braking systems 118a-118d from a circuit fault condition. Additionally, when a power source failure occurs, the isolation module may disconnect the failed power source while maintaining the remaining power sources.In this way, according to one embodiment, the BBW system 102 provides at least one fault-tolerant feature that may enable one or more brake systems 118a-118d to continue operating if a circuit fault condition occurs in the fault-tolerant BBW system 102. When the circuit fault condition is resolved, the isolation module may automatically reconnect the isolated portion of the SLC loop, e.g., the brake systems 118a-118d, to the power sources.

[0023] With reference to Fig. 2, an intelligent actuator unit 203a is shown integrated into a first braking system 118a (i.e., an intelligent braking system 118a) coupled to a first wheel (e.g., 112a) in signal communication with an electromechanical slave actuator 120b integrated into a second braking system 118b (i.e., a slave braking system 118b) coupled to a second wheel (e.g., 112b), according to one embodiment. Although in Fig. 2 only a single intelligent actuator unit (e.g., 203a) and a single electromechanical slave actuator (e.g., 120b) are illustrated, it should be understood that the remaining intelligent actuator units and electromechanical slave actuators implemented in the fault-tolerant BBW system 102 may operate in a similar manner as described herein.

[0024] The intelligent actuator unit 203a includes an actuator controller 201a and an electronically controlled actuator 120a, such as an electronic brake caliper (e-caliper) 120a. Integrating the actuator controller 201a and the electromechanical actuator 120a as a single component enables fast, robust, and diagnosable communication between the actuator controller 201a and the electromechanical actuator 120a, while reducing data latency and reducing overall vehicle weight. Additionally, one or more brake systems (e.g., 118a) can be individually controlled using the actuator controller (e.g., 201a) integrated therein.

[0025] Each actuator controller 201a includes a hardware processor and a memory that stores executable instructions, including, but not limited to, braking algorithms and self-diagnostic algorithms. The hardware processor is configured to read and execute the instructions stored in memory to control the fault-tolerant BBW system 102. Accordingly, the actuator controller 201 can selectively output a low-voltage data command signal (e.g., a low-voltage digital signal) in response to one or more braking events. The data command signal can be delivered via a low-voltage message-based interface or transmission channel, such as a CAN (Controller Area Network) bus. The data command signal initiates one or more actuator driver units (e.g.,202a) located remotely from the intelligent actuator unit 203a installed in the first braking system 118a and the electromechanical slave actuator 120b installed in the second braking system 118b, as discussed in more detail herein.

[0026] The programmable memory included in actuator controller 201a can store flash software to provide flexibility for production implementation. In this way, actuator controller 201a is capable of quickly executing the required control logic to implement and control the actuator drivers (e.g., power circuits) using a brake pedal transition logic method or algorithm programmed or stored in memory.

[0027] The actuator controller 201a (e.g., the memory) may also be preloaded or preprogrammed with one or more brake torque lookup tables (LUTs), i.e., brake torque data tables readily accessible by the microprocessor to perform or execute a braking algorithm. In at least one embodiment, the brake torque LUT stores recorded measurements or readings of the pedal assembly 116 (e.g., the pedal force sensor) and includes an associated commanded braking request for each of the sensed force measurements. Similarly, the actuator controller 201a stores a pedal position LUT corresponding to the measurements or readings monitored by the sensors (e.g., the pedal travel sensor 128) and including a commanded braking request for the sensed position of the pedal.

[0028] The electromechanical slave actuator 120b may be embodied as an electronically controlled mechanical actuator 120b, such as, for example, an electronic brake caliper (E-caliper) 120b. As mentioned above, conventional electromechanical actuators (e.g., 120b) differ from the smart actuator units (e.g., 203a) in that they exclude an actuator controller (e.g., 201). Accordingly, at least one embodiment provides a feature in which each electromechanical actuator is initiated via an actuator controller (e.g., 201a) integrated into a smart brake system (e.g., 118a) located remotely from the slave brake system (e.g., 118b).

[0029] Still referring to Fig. 2, the fault-tolerant BBW system 102 further includes one or more actuator driver units 202a. Although only a single actuator driver 202a is illustrated, it should be understood that multiple actuator driver units may be individually installed within the fault-tolerant BBW system 102. The actuator driver unit 202a receives a constant high-power input signal from one or more power sources 204a and generates a high-frequency switched high-power drive signal that is provided to one of the multiple brake assemblies 118a and 118b. The actuator driver unit 202a may include various power electronic components or circuits, including, but not limited to, H-bridges, heat sinks, application-specific integrated circuits (ASICs), Controller Area Network (CAN) transceivers, or temperature or current sensors.In at least one embodiment, actuator driver unit 202a includes a pulse width modulation (PWM) circuit coupled to an amplifier circuit for converting the constant high-power signal into a high-frequency switched high-power signal. The high-frequency switched high-current signal may have a frequency in the range of about 15 kilohertz (kHz) to about 65 kHz and may have a current value of about 0 A to about 200 A.

[0030] According to at least one embodiment, a single actuator driver 202a may output a high-frequency, switched, high-power signal (e.g., a switched, high-current signal) to drive the electromechanical actuator 120a integrated with the smart brake system 118a, as well as the slave electromechanical actuator 120b installed in the slave brake system 118b. In response to the high-frequency, switched, high-power signal, the smart electromechanical actuator 120a applies a variable (i.e., adjustable) friction force to brake the wheel (e.g., 112a) coupled to the first brake system 118a, while the slave electromechanical actuator 120b applies a variable (i.e., adjustable) friction force to brake the wheel (e.g., 112b) coupled to the second brake system 118b.

[0031] Referring to Fig. 3A-3C illustrate various topologies for implementing a fault-tolerant BBW system 102 according to embodiments. Referring first to Fig. 3A (and also with temporary reference to Fig. 2) illustrates a fault-tolerant BBW system 102 based on a split EBS control topology (e.g., a diagonal split topology) according to one embodiment. In at least one embodiment, the diagonal split topology includes a plurality of brake systems 118a-118d configured to brake a respective wheel 112a and 112b and 114a and 114b of the vehicle 100.

[0032] According to one embodiment, the plurality of brake systems 118a-118d includes a first group of brake systems 118a and 118b, each integrated with an intelligent actuator unit 203a and 203b, respectively, and a second group of brake systems 118c and 118d implementing the electromechanical slave actuator 120c and 120d, respectively. That is, the second group of brake systems 118c and 118d excludes a locally integrated electronic actuator control. Accordingly, the first group of brake systems 118a and 118b may be referred to as intelligent brake systems 118a and 118b, while the second group of brake systems may be referred to as slave brake systems 118c and 118d.

[0033] The intelligent braking systems 118a and 118b and the slave braking systems 118c and 118d each include electromechanical actuators such as an electrically controlled brake caliper (i.e., E-caliper) and a motor, respectively. The electromechanical actuators 120a and 120b included in the intelligent braking systems 118a and 118b may be referred to as intelligent electromechanical actuators 120a and 120b, while the electromechanical actuators 120c and 120d included in the slave braking systems 118c and 118d may be referred to as slave electromechanical actuators 120c and 120d.

[0034] A first intelligent braking system 118a may control the braking of a first wheel 112a located on a driver side of the vehicle 100 (e.g., the driver-side front wheel 112a), and a second intelligent braking system 118b may control the braking of a second wheel 112b located on a passenger side of the vehicle 100 (e.g., the passenger-side front wheel 112b). A first slave braking system 118c may control the braking of a third wheel 114b located on the passenger side of the vehicle 100 (e.g., the passenger-side rear wheel 114b), and a second slave braking system 118d may control the braking of a fourth wheel 114a located on the driver side of the vehicle 100 (e.g., the driver-side rear wheel 114a).

[0035] The fault-tolerant BBW system 102 further includes a first actuator driver unit 202a disposed on a first side (e.g., the driver's side) of the vehicle 100 and a second actuator driver unit 202b disposed on an opposite side (e.g., the passenger side) of the vehicle 100. Each actuator driver unit 202a and 202b includes various power circuits configured to convert a constant high-power input signal output (e.g., non-switched high-power input current) from power sources 204a and 204b into a high-power drive signal configured to drive the electromechanical actuators 120a-120d. The constant high-power input signals from the power sources 204a and 204b can range from about 0 amperes to about 200 amperes.As previously mentioned, the power circuits may include a PWM module and an amplifier circuit configured to convert the output of the power sources 204a and 204b into a high frequency switched high current signal.

[0036] According to the Fig. 3A, the diagonal split topology is achieved by electrically connecting the first smart actuator unit 203a (which controls braking of the driver-side front wheel 112a) to the second actuator driver unit 202b located on the passenger side of vehicle 100, while the second smart actuator unit 203b (which controls braking of the passenger-side front wheel 112b) is electronically connected to the first actuator driver unit 202a located on the driver side of vehicle 100. In this manner, each actuator driver unit 202a and 202b outputs high-power drive signals to braking systems located diagonally from one another, as discussed in more detail herein.

[0037] The first and second intelligent actuator units 203a and 203b are configured to detect a braking event or a braking request in response to signals output by the pedal assembly 116 and the object detection sensors, respectively. Although in Fig. Not shown in Figure 3A, the pedal unit 116 includes various sensors that monitor the pedal, including, but not limited to, a pedal force sensor and a pedal travel sensor. The signal outputs of the pedal force sensor and the pedal travel sensor can be fed to each of the smart actuator units 203a and 203b to provide output redundancy.

[0038] Based on the detected braking event or braking request, the first intelligent actuator unit 203a outputs a first digital command signal that initiates the second actuator driver unit 202b, while the second intelligent actuator unit 203b generates a second digital command signal that initiates the first actuator driver unit 202a. In response to the first digital command signal, the second actuator driver unit 202b generates high-power drive signals that drive both the intelligent electromechanical actuator 120a installed in the first intelligent braking system 118a and the electromechanical slave actuator 120c installed in the second slave braking system 118c and located diagonally from the first intelligent braking system 118a.

[0039] In a similar manner, the second digital command signal initiates the first actuator unit 202a to generate a high-power drive signal that drives both the intelligent electromechanical actuator 120b installed in the second intelligent brake system 118 (e.g., the passenger-side front brake system 118b) and the slave electromechanical actuator 120d installed in the second slave brake system 118d (e.g., the driver-side rear brake system 118d) and located diagonally from the second intelligent brake system 118b.

[0040] How to continue in Fig. As illustrated in Figure 3A, the first smart actuator unit 203a is in electrical communication with the second smart actuator unit 203b. In this way, the smart actuator units 203a and 203b (i.e., the actuator controllers) can share data with each other. The shared data includes, for example, detected braking requests and diagnostic results obtained after performing self-diagnostic tests. Accordingly, one or more of the smart actuator units 203a and 203b can determine whether an actuator controller and / or actuator driver unit 202a and 202b contains a fault or is not operating as expected.

[0041] In at least one embodiment, an isolation module 206 is connected between the first and second power sources 204a and 204b and the remaining electrical system of the fault-tolerant BBW system 102. The isolation module 206 is configured to receive the constant high-power signal generated by the first and second power sources 204a and 204b and to generate a plurality of individual power input signals.

[0042] For example, the isolation module 206 outputs first and second constant high-voltage power signals to each actuator driver unit 202a. The isolation module 206 also outputs first and second low-voltage signals that power the actuator controller integrated with the respective intelligent actuator units 203a and 203b. In this way, the first and second intelligent actuator units 203a and 203b can receive various diagnostic information, including, but not limited to, short-circuit events, open-circuit events, overvoltage events, or other circuit fault events.

[0043] As mentioned above, the isolation module 206 may also be configured to isolate circuit faults, such as wire-to-wire shorts on a signal line loop (SLC), and is capable of limiting the number of modules or detectors that can be disabled by a short-circuit fault on the SLC loop. According to one embodiment, when a wire-to-wire short occurs, the isolation module 206 may automatically create an open in the SLC loop (e.g., an open circuit) to isolate the smart actuator units 203a and 203b from a circuit fault condition. In this way, the fault-tolerant BBW system 102, according to one embodiment, provides at least one fault-tolerant feature. When the fault condition is resolved, the isolation module 206 may automatically reconnect the isolated portion of the SLC loop, e.g., B. reconnect the braking systems 118a-118d to the power sources 204a and / or 204b.

[0044] With reference to Fig. 3B illustrates a fault-tolerant BBW system 102 based on a second split EBS control topology (e.g., a front / rear split topology) according to one embodiment. Similar to the diagonal split topology described above with reference to Fig. 3A, the fault-tolerant BBW system 102 includes a plurality of smart brake systems and a plurality of slave brake systems. However, in the front / rear split topology, a first smart brake system 118a may control the braking of a first wheel 112a located on a driver side of the vehicle 100 (e.g., the driver-side front wheel 112a), while a second smart brake system 118c may control the braking of a second wheel 114b located on a passenger side of the vehicle 100 (passenger-side rear wheel 114b).

[0045] The remaining wheels are coupled to slave brake systems. For example, a first slave brake system 118b controls the braking of a third wheel 112b located on the passenger side of the vehicle 100 (e.g., the passenger-side front wheel 112b), while a second slave brake system 118d can control the braking of a fourth wheel 114a located on the driver side of the vehicle 100 (e.g., the driver-side rear wheel 114a).

[0046] According to the embodiment in Fig. 3B, the front / rear split topology is achieved by electrically connecting the first smart actuator unit 203a (which controls braking of the driver-side front wheel 112a) to the first actuator driver unit 202a located on the front driver side of vehicle 100, while the second smart actuator unit 203b (which controls braking of the passenger-side rear wheel 114b) is electronically connected to the second actuator driver unit 202b located on the rear driver side of vehicle 100. Accordingly, the first actuator driver unit 202a may be installed in close proximity to the first smart braking system 118a, and the second actuator driver unit 202b may be installed in close proximity to the second smart braking system 118c.

[0047] Based on the digital command signals generated by the first intelligent actuator unit 203a, the first actuator driver unit 202a generates a high-performance drive signal that drives both the intelligent electromechanical actuator 120a installed in the first brake system 118a (e.g., the front driver-side brake system 118a) and the electromechanical slave actuator 120b integrated in the second brake system 118b (e.g., the front passenger-side brake system 118b). Similarly, the digital command signals generated by the second intelligent actuator unit 203c initiate the second actuator driver unit 202b to output high-performance drive signals that control both the intelligent electromechanical actuator 120c installed in the third brake system 118c (e.g., the rear passenger-side brake system 118c) and the intelligent electromechanical actuator 120c installed in the fourth brake system 118d (e.g.,the rear driver-side brake system 118d). In this way, a front / rear topology is formed in which the first actuator driver unit 202a drives the electromechanical actuators 118a and 118b arranged at the front of the vehicle 100, while the second actuator driver unit 202b drives the electromechanical actuators 118c and 118d arranged at the rear of the vehicle 100.

[0048] With reference now to Fig. 3C illustrates a fault-tolerant BBW system 102 based on a full electronic braking system (Full EBS) control topology according to one embodiment. The Full EBS control topology of Fig. 3C operates similarly to the split EBS control topologies described above with reference to the Fig. 3A-3B. However, the full EBS control topology differs from Fig. 3C, in that the first and second actuator driver units 202a and 202b are electrically connected to each electromechanical actuator 120a-120d installed in the vehicle 100. In this way, each of the electromechanical actuators 120a-120d can be controlled using a high-power drive signal output by the first actuator driver unit 202a and the second actuator driver unit 202b, respectively. Accordingly, the full-control BBW topology can provide additional fault-tolerance functionality.

[0049] According to at least one embodiment, the intelligent actuator units 203a and 203c are configured to selectively operate in a split topology mode and a full topology mode based on data monitored by the actuator controller integrated in a respective intelligent actuator unit 203a and 203c (see element 201a in Fig. 2). The monitored data includes, but is not limited to, diagnostic results obtained in response to self-diagnostic operations performed by the actuator controllers.

[0050] For example, when operating in the split topology mode, the first actuator driver 202a drives electromechanical actuators included in a first group of brake systems, while the second actuator driver 202b drives electromechanical actuators included in another group of brake systems. When the split topology mode is operated according to a diagonal split topology (see Fig. 3A), the first group of brake systems includes, for example, the second intelligent brake system 118b and the second slave brake system 118d, while the second group includes the first intelligent brake system 118a and the first slave brake system 118c.

[0051] However, if the split topology mode is configured according to a front / rear split topology (see Fig. 3B), the first group of brake systems driven by the first actuator driver unit 202a includes a first intelligent brake system 118a and a first slave brake system 118b, while the second group of brake systems driven by the second actuator driver unit 202b includes a second intelligent brake system 118c and a second slave brake system 118d.

[0052] When operating in full topology mode (see Fig. 3C), each of the first and second actuator driver units 202a and 202b, respectively, is configured to output at least one high-power drive signal that drives each electromechanical actuator of a first group and each electromechanical slave actuator of a second group. That is, during operation in full topology mode, the first intelligent actuator unit 203a and the second intelligent actuator unit 203c, respectively, are capable of driving each electromechanical actuator 120a-120d installed in the vehicle.

[0053] As mentioned hereinabove, the intelligent actuator units 203a and 203b may transition to the full EBS topology mode based on diagnostic results obtained in response to performing a self-diagnostic test. For example, the first intelligent actuator unit 203a may perform a first self-diagnostic operation and transmit first diagnostic results to the second intelligent actuator unit 203c. Similarly, the second intelligent actuator unit 203c may perform its own second self-diagnostic operation and may transmit second diagnostic results to the first intelligent actuator unit 203a. A full EBS topology mode may be initiated if the first diagnostic results and / or the second diagnostic results indicate a fault.

[0054] For example, if the second diagnostic results provided by the second intelligent actuator unit 203c indicate that the second actuator driver unit 202b is faulty, the first intelligent actuator unit 203a may command the second intelligent actuator unit 203c to deactivate the faulty actuator driver unit 202b, and the fault-tolerant BBW system 102 may enter the full EBS topology mode. In turn, the first enhanced intelligent actuator 203a may command the remaining normally operating driver actuator units 202a to output high-power drive signals to each electromechanical actuator 120a-120d installed in the vehicle 100. In this way, if an actuator driver unit (e.g.,202a and 202b) contains a fault, the fault-tolerant BBW system 102 can continue to be fully operated by the remaining normally operating actuator driver unit, thereby providing a fault tolerance feature.

[0055] With reference to Fig.4 shows a flowchart of a method for controlling a fault-tolerant electric braking system according to one embodiment. The method begins at operation 400, and at operation 402, sensor data is output to a first smart actuator unit and a second smart actuator unit. The sensor data may be output from various sensors installed on the vehicle, including, but not limited to, wheel sensors, brake pedal sensors, and / or object detection sensors. At operation 404, it is determined whether at least one smart actuator unit detects a braking event. The braking event is based on the sensor data described above. If no braking event is detected, the method returns to operation 402 and continues monitoring the sensor data.

[0056] However, if at least one of the smart actuator units detects a braking event, the method proceeds to operation 406, and the first and second smart actuator units communicate with each other to compare their respective detected braking event data. For example, a first smart actuator unit may detect a first braking event and may request confirmation that the second smart actuator unit has detected the same or a similar braking event.If the braking event data monitored and generated by the first intelligent actuator unit matches or substantially matches the braking event data monitored and generated by the second intelligent actuator unit, the method proceeds to operation 408, wherein a first actuator controller of the first intelligent actuator outputs a first digital command signal to drive a first actuator driver unit located remotely from the braking systems, and a second actuator controller of the second intelligent actuator unit outputs a second digital command signal to drive a second actuator driver unit also located remotely from the braking systems.

[0057] At operation 410, the first actuator driver unit outputs high-power drive signals that drive a first intelligent electromechanical actuator included in a first braking system and a first electromechanical slave actuator included in a second braking system. Similarly, the second actuator driver unit outputs high-power drive signals that drive a second intelligent electromechanical actuator included in a third braking system and a second electromechanical slave actuator included in a fourth braking system.Accordingly, the first electromechanical actuator included with the first intelligent actuator unit sets a first braking torque applied to the first wheel, and the second electromechanical actuator included in the enhanced actuator unit sets a second braking torque applied to the second wheel, and the method ends at operation 412. In this manner, the first actuator driver is configured to independently drive a first group of braking devices, while the second actuator driver is configured to independently drive another group of braking devices.

[0058] Referring to operation 406, a scenario may occur where the braking event data monitored and generated by the first intelligent actuator unit does not match or substantially match the braking event data monitored and generated by the second intelligent actuator unit. In this case, the method proceeds to operation 414, where a faulty actuator driver unit is identified, and the faulty actuator driver unit is deactivated at operation 416. In at least one embodiment, the actuator controller triggering the faulty actuator driver unit is deactivated to also deactivate the faulty actuator driver unit.At operation 418, the remaining activated smart actuator unit outputs a data command signal to its corresponding actuator driver unit, commanding the actuator driver unit to output high-power drive signals to each electromechanical actuator (i.e., each braking system) installed in the vehicle. At operation 420, each smart electromechanical actuator and each slave electromechanical actuator applies a braking force in response to the high-power drive signal output by a common actuator driver unit, and the method ends at operation 412. In this way, all electromechanical actuators can be controlled in response to a detected braking event, even if an actuator driver unit, or a smart actuator unit controlling an actuator driver unit, is not operating according to expected conditions.

[0059] As discussed in detail above, various embodiments provide a BBW system including a data interface connecting electronic brake system controllers and smart brake actuators. According to one embodiment, a first smart actuator included in a first braking system is controlled by a first actuator controller, while a second smart actuator included in a second braking system is controlled by a second actuator controller. Each actuator controller can output low-voltage data command signals to a respective actuator driver unit (e.g., power circuit) via a low-voltage message-based interface, such as a CAN (Controller Area Network) bus.Accordingly, a flexible BBW system is envisaged that allows flexible design choices, wire length reduction, and flexible braking algorithm implementation while still employing fault tolerance in the system.

[0060] As used herein, the term "module" or "unit" refers to an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), an electronic circuit, an electronic computer processor (shared or dedicated, or group), and a memory executing one or more software or firmware programs, combinational logic circuitry, and / or other suitable components that provide the described functionality. When implemented in software, a module in memory may be embodied as a non-transitory computer-readable storage medium that can be read by processing circuitry and stores instructions that are executed by the processing circuitry to perform a method.

Claims

[1] Vehicle (100) with a fault-tolerant electronic brake-by-wire (BBW) system (102), the vehicle (100) comprising: a plurality of braking systems (118a, 118b, 118c, 118d) configured to control the braking of a respective wheel of the vehicle (100), the plurality of braking systems (118a, 118b, 118c, 118d) comprising: a first braking system (118a) integrated with an intelligent actuator unit (203a) comprising a first actuator controller (201a) and a first electromechanical actuator (120a) configured to adjust a braking force applied to a first wheel (112a) coupled to the first braking system (118a); a second braking system (118b) excluding actuator control and having installed therein a second electromechanical actuator (120b) configured to adjust a braking force applied to a second wheel (112b) coupled to the second braking system (118b); and at least one electronic actuator driver unit (202a, 202b) remote from the first and second brake systems (118a, 118b) and configured to output a high power signal that drives the first and second electromechanical actuators (120a, 120b) in response to receiving a digital command signal from the first actuator controller (201a). [2] The vehicle (100) of claim 1, wherein each of said at least one actuator drive unit (202a, 202b) includes a power circuit configured to output a high frequency switched high power current drive signal that drives said first and second electromechanical actuators (120a, 120b). [3] The vehicle (100) of claim 2, wherein the first actuator controller (201a) is in electrical communication with at least one sensor (126, 128) to detect a braking request and outputs the digital command signal in response to the braking request. [4] The vehicle (100) according to claim 1, further comprising a third brake system (118c) including a second intelligent actuator unit (203c) integrated with a second electronic actuator controller (201) and a third electromechanical actuator (120c), and a fourth (118d) brake system excluding an electronic actuator controller and having a fourth electromechanical actuator (120d) installed therein. [5] The vehicle (100) of claim 4, wherein the at least one electronic actuator driver unit (202a, 202b) includes a first actuator driver unit (202a) that drives the first and second electromechanical actuators (120a, 120b) and a second actuator driver unit (202b) that generates a second high power signal that drives the third and fourth electromechanical actuators (120c, 120d) in response to receiving a second digital command signal from the second actuator controller (201). [6] The vehicle (100) of claim 5, wherein the first and second actuator controllers (201a, 201) generate operating data based on a condition of the respective wheel (112a, 112b) coupled to a respective brake system (118a, 118b, 118c, 118d) of the plurality of brake systems (118a, 118b, 118c, 118d). [7] The vehicle (100) of claim 6, wherein at least one intelligent actuator unit (203a, 203c) diagnoses the operation of at least one of the braking systems of the plurality of braking systems (118a, 118b, 118c, 118d) based on the operating data. [8] The vehicle (100) of claim 7, wherein the first intelligent actuator unit (203a) is in signal communication with the second intelligent actuator unit. [9] Vehicle (100) with a fault-tolerant electronic brake-by-wire (BBW) system (102), the vehicle (100) comprising: a plurality of braking systems (118a, 118b, 118c, 118d) configured to control the braking of the respective wheels of the vehicle (100), wherein the plurality of braking systems (118a, 118b, 118c, 118d) comprises a first group of braking systems (118a, 118c), each connected to an electronically intelligent actuator unit (203a, 203c) including an electronic actuator controller (201a, 201) and an electromechanical actuator (120a, 120c), and a second group of braking assemblies, each excluding an electronic actuator controller and provided with an electromechanical slave actuator (120b, 120d) installed therein; and first and second actuator driver units (202a, 202b) located remote from the braking systems, each of the first and second actuator driver units (202a, 202b) being in electrical communication with each electromechanical actuator (120a, 120c) of the first group and each electromechanical slave actuator (120b, 120d) of the second group. [10] A method for controlling a fault-tolerant electronic brake-by-wire (BBW) system (102), the method comprising: integrating a first intelligent actuator unit (203a) including a first electrical actuator control (201a) into a first intelligent braking system (118a) and integrating a first electromechanical slave actuator (120a) excluding an electronic actuator control into a first slave braking system (118b); and outputting a first digital command signal via the first electronic actuator control (201a) which initiates a first actuator driver unit (202a) arranged remotely from the first intelligent braking system (118a) and the first slave braking system (118b), wherein the first actuator driver unit (202a) outputs, in response to the first digital command signal, a high-performance drive signal that controls the braking of a wheel (112a) coupled to the first brake system (118a) and the braking of a second wheel (112b) coupled to the first slave brake system (118b).

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