Abstract:
An electric brake system architecture for an aircraft with two or more electrical braking subsystems including brake system controls configured to communicate pilot pedal commands to electric brake actuator controllers that apply or release brakes in wheel groups. The system allows independent brake activation of wheel groups through a plurality of brake system controls and electric brake actuator controllers. The electric braking system further includes remote data consolidators to collect and transmit wheel data to brake system controls through a digital data communication bus. The system reduces aircraft weight, prevents inadvertent braking, and prevents error propagation between subsystems.

Description:
TECHNICAL FIELD 
     Embodiments of the present invention relate generally to aircraft control systems, and more particularly to aircraft electrical brake control systems. 
     BACKGROUND 
     Historically aircraft braking control has been operated via direct cable or hydraulic connection. Cable and hydraulic control connections suffered from weight, performance and reliability issues. Many of these issues have been improved upon by using electrically actuated and controlled brake systems. Electrically actuated and controlled brake systems are colloquially referred to as “brake by wire” systems. 
     It is desirable to have an electric brake system that provides reliable redundancy for aircraft braking systems. In addition, it is desirable to have a system that protects against inadvertent brake applications where a braking subsystem applies the brakes when it shouldn&#39;t. Other desirable features and characteristics of embodiments of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background. 
     BRIEF SUMMARY 
     An electric brake system architecture as described herein is suitable for use with an aircraft having two or more electrical braking subsystems. These subsystems include brake system controls configured to communicate pilot pedal commands to an electric brake actuator controller or controllers that apply or release brakes for designated wheel groups. The brake subsystems utilize a plurality of control units configured to generate brake control signals for the landing gear wheels in response to pilot input. The brake subsystems may also use at least one electric brake actuator controller coupled to and controlled by the brake system control unit. These actuator controllers are configured to generate brake mechanism control signals for the landing gear brakes. In one practical embodiment, the electric brake system has at least one left landing gear wheel group controlled by one brake subsystem and at least one right landing gear wheel group controlled by another brake subsystem. Here, left and right refer to the port and starboard of the aircraft respectively relative to the center line of the plane. 
     In a further example embodiment, the electric braking system further includes remote data concentrators that collect and transmit wheel data to brake system control units through a digital data communication bus. The system allows independent brake activation of wheel groups through a plurality of brake system control units, electric brake actuator controllers, and electrical power distribution. The system reduces aircraft weight and prevents inadvertent braking and error propagation between subsystems. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more complete understanding of the present invention may be derived by referring to the detailed description and claims when considered in conjunction with the following figures, wherein like reference numbers refer to similar elements throughout the figures. 
         FIG. 1  is a schematic representation of a general electrical braking system for an aircraft according an example to an embodiment of the invention; 
         FIG. 2  is a diagram of a landing gear wheel configuration for an example aircraft that utilizes an electrical braking system configured in accordance with an embodiment of the invention; 
         FIG. 3  is a schematic representation of one example deployment of the electrical braking system depicted in  FIG. 1  according to an example embodiment of the invention; and 
         FIG. 4  is a schematic representation of an electrical power distribution system of the electrical braking system depicted in  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description is merely illustrative in nature and is not intended to limit the embodiments of the invention or the application and uses of such embodiments. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description. 
     Embodiments of the invention may be described herein in terms of functional and/or logical block components and various processing steps. It should be appreciated that such block components may be realized by any number of hardware, software, and/or firmware components configured to perform the specified functions. For example, an embodiment of the invention may employ various electric brake actuators, integrated circuit components, e.g. memory elements, digital signal processing elements, logic elements, look-up tables, or the like, which may carry out a variety of functions under the control of one or more microprocessors or other control devices. In addition, those skilled in the art will appreciate that embodiments of the present invention may be practiced in conjunction with any number of digital data transmission protocols and/or aircraft configurations, and that the system described herein is merely one example embodiment of the invention. 
     For the sake of brevity, conventional techniques and components related to signal processing, aircraft braking, braking control, and other functional aspects of the systems and the individual operating components of the systems may not be described in detail herein. Furthermore, the connecting lines shown in the various figures contained herein are intended to represent example functional relationships and/or physical couplings between the various elements. It should be noted that many alternative or additional functional relationships or physical connections may be present in an embodiment of the invention. 
     The following description refers to elements or nodes or features being “connected” or “coupled” together. As used herein, unless expressly stated otherwise, “connected” means that one element/node/feature is directly joined to or directly communicates with another element/node/feature, and not necessarily mechanically. Likewise, unless expressly stated otherwise, “coupled” means that one element/node/feature is directly or indirectly joined to or directly or indirectly communicates with another element/node/feature, and not necessarily mechanically. Thus, although the schematics shown in the figures depict example arrangements of elements, additional intervening elements, devices, features, or components may be present in an embodiment of the invention (assuming that the functionality of the system is not adversely affected). 
     Embodiments of the invention are described herein in the context of one practical application, namely, an aircraft braking system. In this context, the example technique is applicable to provide redundancy and avoid inadvertent brake application on an aircraft. Embodiments of the invention, however, are not limited to such aircraft applications, and the techniques described herein may also be utilized in other applications. 
       FIG. 1  is a schematic representation of a general electrical braking system  100  for an aircraft according to an example embodiment of the invention. The system described herein can be applied to any number of electrical braking configurations for an aircraft, and electric brake system  100  is depicted in a generic manner to illustrate its deployment flexibility. In this example, the electric brake system  100  may include a left side electrical braking subsystem architecture  101  and a right side braking subsystem architecture  111 . The terms “left” and “right” as used herein refer to the port and starboard of the aircraft respectively relative to the center line of the plane. These terms are used herein for convenience of description and are not intended to limit or restrict the scope or application of the invention in any way. In practice, the two subsystem architectures may be independently controlled in the manner described below. In operation, the electric brake system can independently generate and apply brake actuator control signals for each wheel of the aircraft. The electrical power distribution for the system embodiments are not shown in  FIG. 1  and will be discussed with respect to  FIG. 4  below. 
     The left side electrical braking subsystem architecture  101  may include a left pilot pedal  102  configured to provide pilot input to left subsystem architecture  101 , at least one left brake system control unit (“BSCU”)  104  coupled to left pilot pedal  102 , and at least one left electric brake actuator control (“EBAC”)  106  configured to generate brake mechanism control signals for at least one left wheel group  108 . 
     The pilot physically manipulates the left pilot pedal  102  to generate a left pilot pedal physical input. The left pilot pedal physical input is measured from its natural position by a hardware servo or an equivalent component, converted into a left BSCU pilot command control signal by a transducer or an equivalent component, and sent to the at least one left BSCU  104 . 
     An embodiment may use any number of BSCUs  104  but the example described below uses only one left side BSCU  104 . The BSCU is an electronic control unit that has embedded software to digitally compute the braking command. The electrical/software implementation allows further optimization and customization of braking performance and feel. The BSCU  104  may be generally realized by a microcontroller, which includes suitable processing logic and software that is configured to carry out the BSCU operations described herein. The microcontroller may be a computer such as, without limitation, a PowerPC  555  that hosts software and provides external interfaces for the software. The BSCU monitors various airplane inputs to provide control functions such as, without limitation, pedal braking, parking braking, autobrake and gear retract braking. In addition, the BSCU blends the antiskid command (which could be generated internal or external from the BSCU) to provide optimal control of braking. The BSCU  104  obtains pedal control signals and wheel data such as wheel speed, rotational direction value for the wheels, and tire pressure as described below. The BSCU  104  processes its input signals and generates one or more BSCU output signals that are used as input to EBACs  106 . The BSCU transmits the brake command to the EBAC through a digital data bus to minimize airplane wiring. In this generalized architecture, each BSCU  104  can generate independent output signals for use with any number of the EBACs  106  under its control. 
     Each BSCU  104  may be coupled to one or more associated EBACs  106 . An EBAC  106  may be realized as a microcontroller which includes suitable processing logic and software that is configured to carry out the EBAC operations described herein. The microcontroller may be a computer such as, without limitation, a PowerPC  555  that hosts software and provides external interfaces for the software. Each EBAC  106  obtains BSCU output signals, processes those signals, and generates the actuator signals that are used to control the brake mechanisms for the wheels. 
     Each wheel group  108  includes one or more wheels with any arrangement, and each wheel group  108  may have a designated EBAC.  FIG. 1  only shows one wheel group  108  for the sake of simplicity. In  FIG. 1 , the wheel group  108  is generally depicted as a two-dimensional array having one or more rows and one or more columns; however, this general configuration is not meant to limit or restrict the scope or the application of the invention in any way. Indeed, the example embodiment described below includes two wheels in each wheel group  108 : a fore wheel and an aft wheel. 
     Each wheel in the wheel group  108  includes a brake mechanism controlled by the EBACs  106  to apply, release, modulate, and otherwise control the brakes. In this regard, EBACs  106  generate electric brake actuator (EBA) signals in response to the respective BSCU output signals. The EBA signals are suitably formatted and arranged for compatibility with the particular brake mechanisms on the aircraft. In practice, the EBA signals may be regulated to carry out anti-skid and other braking maneuvers. Those skilled in the art are familiar with aircraft brake mechanisms and the manner in which they are controlled, and such known aspects will not be described in detail here. 
     The right side electrical braking subsystem architecture  111  has a structure that is similar to the left side electrical braking subsystem architecture  101 . Accordingly, the configuration and operation of these components will not be redundantly described herein. As shown in  FIG. 1 , the right side electrical braking subsystem architecture  111  may include a right pilot pedal  110  configured to provide pilot input to right subsystem architecture  111 , at least one right BSCU  112  coupled to right pilot pedal  110 , and at least one right EBAC  114  configured to generate brake mechanism control signals for at least one right wheel group  116 . 
     Although  FIG. 1  shows a general wheel grouping scheme example, where each landing gear includes N wheel groups coupled to N EBACs respectively, the example embodiment includes a left landing gear having four wheels (two wheel groups) and a right landing gear having four wheels (two wheel groups) as shown in the wheel configuration of  FIG. 2 . In this regard,  FIG. 2  is a diagram of a landing gear wheel configuration  200  for an example aircraft. The landing gear wheel configuration  200  includes a left landing gear wheel arrangement  238  and a right landing gear wheel arrangement  240 . 
     The left landing gear wheel arrangement  238  may include a left outboard wheel group  204  and a left inboard wheel group  212 . The left outboard wheel group  204  may include a fore left outboard wheel  206  and an aft left outboard wheel  208 . Likewise, the left inboard wheel group  212  may include a fore left inboard wheel  214  and an aft left inboard wheel  216 . The wheels in the left wheel groups  204  and  212  are coupled to respective axles  242  and  244  respectively. In this example, the brake system includes a left outboard EBAC  202  coupled to the left outboard wheel group  204 , and a left inboard EBAC  210  coupled to the left inboard wheel group  212 . Left outboard EBAC  202  is suitably configured to generate brake control signals for wheels  206 / 208 , while left inboard EBAC  210  is suitably configured to generate brake control signals for wheels  214 / 216  in response to wheel data as explained in detail below. 
     The right landing gear wheel arrangement  240  is similar to the left landing gear wheel arrangement  238 . The right landing gear wheel arrangement  240  may include a right outboard wheel group  228  and a right inboard wheel group  220 . The right outboard wheel group  228  includes a fore right outboard wheel  230  and an aft right outboard wheel  232 . The right inboard wheel group  220  includes a fore right inboard wheel  222  and an aft right inboard wheel  224 . The wheels in the right wheel groups  220  and  228  are coupled to respective axles  246  and  248  respectively. In this example, the brake system includes a right outboard EBAC  226  coupled to the right outboard wheel group  228 , and a right inboard EBAC  218  coupled to the right inboard wheel group  220 . Right outboard EBAC  226  is suitably configured to generate brake control signals for wheels  230 / 232 , while right inboard EBAC  218  is suitably configured to generate brake control signals for wheels  222 / 224  in response to wheel data as explained in detail below. 
     The landing gear wheel configuration  200  shown in  FIG. 2  may be supported by an electrical braking system for an aircraft such as that shown in  FIG. 3 .  FIG. 3  is a schematic representation of one example deployment of the general electrical braking system architecture for an aircraft depicted in  FIG. 1 . The electrical braking system  300  shown in  FIG. 3  may generally include a left side electric brake subsystem architecture  301  and a right side electric brake subsystem architecture  303  similar to  FIG. 1 . Electrical braking system  300  may share some components, features, and functionality with electrical braking system  100  and/or with wheel configuration  200 , and such common aspects will not be redundantly described in detail with respect to electrical braking system  300 . 
     In the example deployment shown in  FIG. 3 , each of the right side and the left side electric brake subsystem architectures  301  and  303  may include one pilot pedal, one BSCU, one inboard-outboard pair of EBACs; one inboard-outboard pair of wheel groups, and four landing gear wheels including one fore-aft pair of wheels for each wheel group. Each left side and right side electric brake subsystem architecture  301  and  303  respectively may also include a plurality of sensors, a plurality of remote data concentrators (RDCs), and a digital data communication bus. Each sensor may be coupled to their respective wheel, and each sensor may be suitably configured to measure wheel data for each of their respective wheel that can be utilized by electrical braking system  300 . Each RDC is coupled to a respective wheel, and each RDC is configured to collect and transmit its wheel data to a BSCU. The digital data communication bus or buses may be configured to communicate the wheel data from the RDCs to the brake system control units. 
     For this example deployment, as shown in  FIG. 3 , the left electric brake subsystem architecture  301  may include: a left pilot pedal  302 ; a left BSCU  306 ; a left outboard EBAC  308 ; a left inboard EBAC  310 ; a left outboard wheel group  312 ; a left inboard wheel group  324 ; four left sensors (reference numbers  313 ,  317 ,  327  and  329 ), and four RDCs (reference numbers  314 ,  318 ,  328 , and  330 ) corresponding to each wheel in each of the wheel groups in the left subsystem architecture  301 . 
     Left pilot pedal  302  and left BSCU  306  are generally configured as described above with respect to  FIG. 1 . In this example, the left subsystem architecture  301  employs one BSCU  306 , which is coupled between left pilot pedal  302  and each of the left EBACs  308  and  310 . As described in more detail below, left BSCU  306  is also coupled to the four RDCs to receive wheel data for the respective wheels. 
     Left outboard EBAC  308  is connected to the left outboard RDCs  314 / 318  and is configured to generate brake control signals for the left outboard landing gear wheels  316  and  320  in response to wheel data collected by the left outboard RDCs  314 / 318 . Left inboard EBAC  310  is coupled to the left inboard RDCs  328 / 330  and configured to generate brake control signals for the left inboard landing gear wheels  328  and  330  in response to wheel data collected by the left inboard RDCs  328 / 330 . 
     The left subsystem architecture  301  utilizes four RDCs (reference numbers  314 ,  318 ,  328 , and  330 ) and a suitable data communication bus  333  for wheel data communication. An RDC is generally configured to receive, measure, detect, or otherwise obtain data for processing and/or transmission to a subsystem. In this example embodiment, the digital data communication bus  333  is configured to communicate the wheel data from the RDCs (reference numbers  314 ,  318 ,  328 , and  330 ) to the BSCU  306  using any suitable data communication protocol and any suitable data transmission scheme. In an alternate embodiment, RDCs (reference numbers  314 ,  318 ,  328 , and  330 ) may be configured to communicate the wheel data to the EBACs  308 / 310 . In yet another embodiment, the RDCs (reference numbers  314 ,  318 ,  328 , and  330 ) may be configured to communicate the wheel data to the BSCU  306  as well as to the EBACs  308 / 310 . Each RDC is installed at or near the end of each axle; thus, a given RDC may be mounted in an outboard location or an inboard location. For this example embodiment, the left electric brake subsystem architecture  301  includes a fore left outboard RDC  314  coupled to the fore left outboard wheel  316 , an aft left outboard RDC  318  coupled to the aft left outboard wheel  320 , a fore left inboard RDC  328  coupled to the fore left inboard wheel  326 , and an aft left inboard RDC  330  coupled to the aft left inboard wheel  332 . 
     The left outboard EBAC  308  may be configured to generate brake control signals for the outboard wheels  316  and  320  in response to wheel data collected by the RDCs  314  and  318 . The left inboard EBAC  310  may be configured to generate brake control signals for the inboard wheels  326  and  332  in response to wheel data collected by the RDCs  328  and  330 . The left sensors (reference numbers  313 ,  317 ,  327  and  329 ) may include, for example, a wheel speed sensor, a rotation sensor, a brake temperature sensor, and/or an air pressure sensor coupled to their respective wheel (reference number  316 ,  320 ,  326  and  322 ) and are configured to measure data corresponding to their respective wheel (reference number  314 ,  320 ,  326  and  322 ). In this example embodiment, left sensors or portions thereof may be realized in the RDCs. 
     In operation, the left BSCU  306  is configured to generate pilot command control signals for EBACs  308  and  310 , which in turn generate brake actuator control signals for the landing gear brakes in their respective wheel group  312  and  324 . BSCU  306  generates its output control signals in response to the wheel data measured by the left sensors (reference numbers  313 ,  317 ,  327  and  329 ). Consequently, EBACs  308  and  310  also generate their output control signals in response to the BSCU command. 
     The right side electrical braking subsystem architecture  303  has a structure that is similar to the left side electrical braking subsystem architecture  301 . For this example deployment, as shown in  FIG. 3 , the right electric brake subsystem architecture  303  may include a right pilot pedal  336 , a right BSCU  338 ; a right outboard EBAC  342 , a right inboard EBAC  340 , a right outboard wheel group  356 , a right inboard wheel group  344 , four right sensors (reference numbers  345 ,  347 ,  360  and  362 ), and four RDCs (reference numbers  345 ,  347 ,  359 , and  361 ) corresponding to their respective wheel in each of the wheel groups in the right subsystem architecture  303 . These RDCs communicate wheel data or antiskid data to BSCU  338  via a suitable digital data communication bus  365 . These components are coupled together to operate as described above for left subsystem architecture  301 , however, the right-side processing is preferably independent of the left-side processing. 
       FIG. 4  is a schematic representation of an electrical power distribution arrangement suitable for use with electrical braking system  300 . As shown in  FIG. 4 , the example electrical power distribution arrangement includes a left side electric power distribution subsystem  309  configured to supply power to the left side electrical braking subsystem architecture  301  and a right side electric power distribution subsystem  311  configured to supply power to the right side electrical braking subsystem architecture  303 . In this regard, separate EBPSU improves system availability from possible failures and threats that can result in loss of power. 
     The electrical power distribution arrangement may include four electric brake power supply units (“EBPSUs”): a left outboard EBPSU  366 ; a left inboard EBPSU  368 ; a right outboard EBPSU  372 ; and a right inboard EBPSU  370 . The left outboard EBPSU  366  and the left inboard EBPSU  368  are each configured to supply power to the left BSCU  306 . The left RDCs (reference numbers  314 ,  318 ,  328  and  330 ) are configured to receive power from the left BSCU  306  via the left EBPSUs  366 / 368 . Similarly, the right outboard EBPSU  372  and the right inboard EBPSU  370  are each configured to supply power to the right BSCU  338 . The right RDCs (reference numbers  346 ,  348 ,  360 , and  362 ) are configured to receive power from the right BSCU  338  via the right EBPSUs  370 / 372 . Additionally, the BSCUs may be configured to control the EBPSUs. 
     While at least one example embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the example embodiment or embodiments described herein are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing the described embodiment or embodiments. It should be understood that various changes can be made in the function and arrangement of elements without departing from the scope of the invention, where the scope of the invention is defined by the claims, which includes known equivalents and foreseeable equivalents at the time of filing this patent application.