Patent Publication Number: US-8974012-B2

Title: Autobraking interlock for an aircraft electric brake system

Description:
Priority Claim 
     The present application is a continuation of U.S. patent application Ser. No. 11/615,793, filed on Dec. 22, 2006, the disclosure of which is incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     Embodiments of the present invention relate generally to an electric brake system for an aircraft. More particularly, embodiments of the present invention relate to an autobrake interlock system for an electric brake system of an aircraft. 
     BACKGROUND 
     Many aircraft utilize brake systems having brake mechanisms that are controlled by direct cable or hydraulic control architectures. Modern aircraft are beginning to replace conventional cable actuated and hydraulic actuated aircraft brake systems with electrically actuated and electrically controlled brake systems. An aircraft brake system should be designed with safety features that prevent inadvertent braking (i.e., the application of brakes in the absence of a legitimate braking command from the pilot or an automated aircraft system). Moreover, an aircraft brake system should include sufficient processing redundacy to provide reliable brake control and robustness. 
     BRIEF SUMMARY 
     An electric autobrake interlock system suitable for use with an aircraft includes an autobrake interlock arrangement that controls whether or not operating power is provided to the electric brake actuators that govern wheel braking. The autobrake interlock arrangement includes a hardware-based power control architecture that regulates operating power for brake mechanisms in parallel with a software-based command architecture that generates brake mechanism control signals. In one embodiment, a plurality of such interlock arrangements are employed in an independent manner for a plurality of wheel brakes (or for a plurality of wheel brake groups), thus providing reliability and robustness. The electric autobrake interlock system makes use of throttle resolver angle (TRA) data to drive the autobrake interlock to enable/disable application of the autobrake. The TRA data is used by the aircraft engines and is made available on the aircraft&#39;s digital communication system. In practice, the autobrake design may make use of network architecture already present on the airplane (there may be no added data transport design elements added for dedicated autobrake use). 
     The above and other aspects of the invention may be carried out in one embodiment by a control arrangement for an electric autobrake interlock system of an aircraft. The control arrangement includes an actuator power control architecture configured to process the autobrake input signals and to enable/disable operating power for a brake actuation of the electric brake system. The control arrangement also includes autobrake command architecture in parallel with the actuator power control architecture. The autobrake command architecture is configured to process the autobrake input signals and to generate a brake actuation control command in response to autobrake actuation data for the electric brake system. The actuator power control architecture is capable of preventing actuation of the brakes independently of the antobrake command architecture. Conversely, the autobrake command architecture is capable of preventing actuation of the brakes independently of the actuator power control architecture. 
     The above and other aspects of the invention may be carried out in another embodiment by a method for providing an autobrake interlock for an electric brake system of an aircraft. The method involves receiving autobrake actuation data, processing the autobrake actuation data, and if the autobrake actuation data does not indicate an autobrake application condition, regulating operating power for a brake mechanism to temporarily disable the brake mechanism. Concurrently with and independent of this power control scheme, the method processes the autobrake actuation data, and if the autobrake actuation data does not indicate the autobrake application condition, the method prevents actuation of the brake mechanism. The method provides actuation control for the brake mechanism and is particular for the electric brake actuators if the following two actions happen concurrently: the operating power is provided to enable the electric brake actuators, and a brake actuation control is commanded in response to a legitimate autobrake application condition. 
     The above and other aspects of the invention may be carried out in another embodiment by an electric autobrake interlock system for an aircraft. The electric autobrake interlock system includes a brake mechanism for a wheel of the aircraft and an autobrake control architecture coupled to the brake mechanism. The autobrake control architecture includes an autobrake command control configured to generate brake mechanism command signals for the brake mechanism and in particular for the electric brake actuators in response to autobrake actuation data, and an interlock mechanism configured to regulate operating power for the brake mechanism and in particular for the electric brake actuators in response to the autobrake actuation data. The interlock mechanism operates concurrently with operation of the autobrake command control, and independent of the autobrake command control. 
     This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identity key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. 
    
    
     
       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 an aircraft electric brake system; 
         FIG. 2  is a diagram that illustrates independent processing channels of an aircraft electric brake system; 
         FIG. 3  is a schematic representation of a portion of an aircraft electric brake system; 
         FIG. 4  is a schematic, representation of an electric autobrake interlock system, for a portion of an aircraft electric brake system; and 
         FIG. 5  is a flow chart that illustrates an autobrake interlock process for an aircraft electric autobrake interlock system. 
     
    
    
     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 realised 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 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 a variety of different aircraft brake systems and 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 brake systems, brake system controls, 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  FIGS. 1-3  depict example arrangements of elements, additional intervening elements, devices, features, or components may he present in an embodiment of the invention. 
     An aircraft as described herein employs an electric brake system, which may be powered by any suitable power supply, such as a main aircraft battery, or an active aircraft power supply that is operational when the aircraft engine(s) are running. Advance airplanes employ autobrake. Autobrake is a type of automatic brake system that frees the pilot to perform other tasks during takeoff or landing at times when the aircraft&#39;s brake system can he handled by automated systems. When landing, the autobrake allows the pilot to monitor other systems and control the airplane while the braking is handled automatically. The aircraft automatically engages wheel braking upon touchdown on the runway. An additional advantage of engaging the autobrake instead of using pedal braking is the/uniform deceleration made possible by the closed loop brake control algorithms. The degree of braking may be selected, and brake application is automatically modulated such that the aircraft decelerates at the selected level regardless of other deceleration factors such as aircraft drag, thrust reversers, or spoilers. When taking off, the aircraft&#39;s autobrake can be set to a rejected takeoff (RTO) mode. When, in the RTO setting, the aircraft monitors certain statics indicators and engages RTO braking depending on those indicators. For example, if thrust reversing is activated, or if the pilot returns both throttles to the “idle” position. The electric autobrake system includes an interlock feature that is independent of the autobrake command feature that generates the various brake mechanism control signals. The interlock feature is suitably configured to prevent inadvertent, application of the aircraft autobrakes by removing the actuation power from the electric brake actuators. Thus, even if the actuators are inadvertently commanded to apply brakes, the lack of actuation power renders them unable to respond to the inadvertent autobrake command. Similarly, if the actuation power is supplied to the actuators, the lack of autobrake command, renders them unable to inadvertently apply brakes. 
       FIG. 1  is a schematic representation of an example embodiment of an electric brake system  100  for an aircraft. In the example embodiment shown, in  FIG. 1 , the aircraft employs a left electric brake subsystem architecture  102  and a right electric brake subsystem architecture  104 , which are similarly configured. The terms “left” and “right” refer to the port and starboard of the aircraft, respectively. In practice, the two subsystem architectures  102 / 104  may be independently controlled in the manner described below. For simplicity, only left electric brake subsystem architecture  102  is described in detail below. It should be appreciated that the following description also applies to right electric brake subsystem architecture  104 . 
     For this example deployment, left electric brake subsystem architecture  102  generally includes: a throttle lever  106 ; a brake system control unit (BSCU)  110 ; an outboard electric brake actuator control (EBAC)  112  coupled to BSCU  110 ; an inboard EBAC  114  coupled to BSCU  110 ; an outboard wheel group that includes a fore wheel  116  and an aft wheel  118 ; an inboard wheel group that includes a fore wheel  120  and an aft wheel  122 ; electric brake mechanisms (not shown in  FIG. 1 ) coupled to the EBACs; and remote data concentrators (reference numbers  132 ,  134 ,  136 , and  138 ). Each electric brake mechanism includes at least one electric brake actuator (reference number  124 ,  126 ,  128  and  130 ) that is controlled by the respective EBAC. The electric brake mechanisms and the remote data concentrators correspond to each wheel of left electric brake subsystem architecture  102 . Although, not shown in  FIG. 1 , an embodiment may have more than one electric brake mechanism and more than, one remote data concentrator per wheel. 
     Electric brake system  100  can be applied to any number of electric braking configurations for an aircraft, and electric brake system  100  is depicted in a simplified manner for ease of description. An embodiment of electric brake system  100  as deployed may include, any number of BSCUs, any number of EBACs coupled to and controlled by each BSCU, and any number of brake mechanisms for each wheel (or for each group of wheels). In operation, electric brake system  100  can independently generate and apply brake actuator control, signals for each wheel of the aircraft or concurrently for any group of wheels. 
     The elements in left electric brake subsystem architecture  102  can be coupled together using a data communication bus or any suitable interconnection arrangement or architecture. For example, a digital data communication bus or buses may be configured to communicate EBAC control signals from BSCU  110  to the EBACs, to communicate actuator control signals from the EBACs to the electric brake actuators  124 / 126 / 128 / 130 , etc. Briefly, BSCU  110  reacts to manipulation of throttle levers  106 / 142  and generates control signals that are received by EBACs  112 / 114 . In turn, EBACs  112 / 114  generate brake mechanism control signals that are received by electric brake mechanisms and in particular by the actuators  124 / 126 / 128 / 130 . In turn, the electric brake actuators  124 / 126 / 128 / 130  engage to impede or prevent rotation of the respective wheels. These features and components are described in more detail below. 
     Throttle levers  106  and  142  are configured to provide inputs to electric brake system  100 . A pilot may physically manipulate throttle lever  106  and  142 , resulting in rotation or movement (i.e., some form of physical input) of throttle lever  106  and  142 . For example, electric brake system  100  (and BSCU  110  in particular) may be configured to prevent the application of autobrakes if the thrust levers are not at idle, as explained in detail in context of  FIG. 4  below. This physical rotation or throttle resolver angle (TRA) is measured from us natural position by one or more thrust lever sensors, converted into a BSCU control signal and sent to BSCU  110 . The BSCU may convey a desired autobraking condition for brake actuators  124 / 126 / 128 / 130 , or may disable brake actuators  124 / 126 / 128 / 130  as explained in detail in context of  FIG. 4  below. 
     An embodiment of electric brake system  100  may use any number of BSCUs  110 . For ease of description, this example includes only one BSCU  110 . BSCU  110  is an electronic control unit that has embedded software that digitally computes EBAC control signals that represent braking commands. The electrical and software implementation allows further optimization and customization of braking performance and feel if needed for the given aircraft deployment. 
     BSCU  110  may be implemented or performed with a general purpose processor, a content addressable memory, a digital signal processor, an application, specific integrated circuit, a field programmable gate array, any suitable programmable logic device, discrete gate or transistor logic, discrete hardware components. Or any combination thereof designed to perform the functions described herein. A processor may be realized as a microprocessor, a controller, a microcontroller, or a state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a digital signal processor and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a digital signal processor core, or any other such configuration. In one embodiment, BSCU  110  is implemented with a computer processor (such as a PowerPC  555 ) that hosts software and provides external interfaces for the software. 
     BSCU  110  monitors various aircraft inputs to provide control functions such as, without limitation: pedal braking; parking braking; automated braking; and gear retract braking. In addition, BSCU  110  blends antiskid commands (which could be generated internally or externally relative to BSCU  110 ) to provide enhanced braking performance. BSCU  110  obtains pilot command control signals from brake pedals (not shown in  FIG. 1 ), along with additional command control signals such as input from both throttle levers  106 / 42 . BSCU  110  may also receive additional control data (e.g., wheel speed, rotational direction, tire pressure, etc.) from remote data concentrators  132 / 134 / 136 / 138 . BSCU  110  processes its input signals and generates one or more EBAC control signals that are received by EBACs  112 / 114 . In practice, BSCU  110  transmits the EBAC control signals to EBACs  112 / 114  via a digital data bus. In a generalized architecture (not shown), each BSCU can generate independent output signals for use with any number of EBACs under its control. 
     BSCU  110  is coupled to EBACs  112 / 114  in this example. Each EBAC  112 / 114  may be implemented, performed, or realised, in the manner described above for BSCU  110 . In one embodiment, each EBAC  112 / 114  is realised with a computer processor (such as a PowerPC  555 ) that hosts software, provides external interfaces for the software, and includes suitable processing logic that is configured to carry out the various EBAC operations described herein. Each EBAC  112 / 114  obtains EBAC control signals from BSCU  110 , processes the EBAC control signals, and generates the brake mechanism control signals (brake actuator signals) for its associated electric brake mechanisms. 
     Notably, the functionality of BSCU  110  and EBACs  112 / 114  may be combined into a single processor-based feature or component. In this regard, BSCU  110 , EBAC  112 , EBAC  114 , or any combination thereof can be considered to be an brake control architecture for electric brake system  100 . Such brake control architecture includes suitably configured processing logic, functionality, and features that support the autobrake control operations described herein. 
     Each wheel may include an associated electric brake mechanism, and each brake mechanism may include one or more electric brake actuators. Consequently, braking for each wheel may be independently and individually controlled by electric brake system  100 . Each electric brake actuator is suitably configured to receive actuator control signals from its respective EBAC, wherein the actuator control signals influence adjustment of the electric brake actuator. In this embodiment, each electric brake actuator in electric brake system  100  is coupled to and controlled by an EBAC. In this manner, EBACs  112 / 114  control the electric brake actuators to apply, release, modulate, and otherwise control the application of the wheel brakes. In this regard, EBACs  112 / 114  generate the brake control signals in response to the respective EBAC control signals generated by BSCU  110 . The brake control signals are suitably formatted and arranged for compatibility with the particular brake system utilized by the aircraft. Those skilled in the art are familiar with aircraft brake mechanism and the general manner in which the brake is controlled and such known aspects will not be described in detail here. 
     The left electric brake subsystem architecture  102  may include or cooperate with a suitably configured power control subsystem  140 . Power control subsystem  140  may be coupled to BSCU  110 , to EBACs  112 / 114  (and/or to other components of electric brake system  100 ). In this embodiment, power control subsystem  140  is suitably configured to provide, apply, remove, switch, or otherwise regulate the operating power for the electric brake mechanisms and/or the electric brake actuators as needed. For example, power control subsystem  140  can remove power from EBACs  112 / 114  and/or other components of left electric brake subsystem architecture  102  as needed to provide an interlock feature for electric brake system  100 . As described in more detail below, power control subsystem  140  may be implemented with a left outboard power supply unit and a left inboard power supply unit that function in an independent manner to regulate operating power for the left outboard and left inboard electric brake components. 
     Right electric brake subsystem architecture  104  has a structure that is similar to left electric brake subsystem architecture  102  (common features, functions, and elements will not be redundantly described here). For this example deployment, as shown in  FIG. 1 , right electric brake subsystem architecture  104  includes: a right throttle lever  142  that is separate and distinct from throttle lever  106 ; a BSCU  146 ; an inboard EBAC  148 ; an outboard EBAC  150 ; and a power control, subsystem  152  that is separate and distinct from power control subsystem  140 . The two sides of electric brake system  100  receive autobrake brake actuation data, from both throttle levers  100 / 142 . Alternatively, the two sides of electric brake system  100  may utilize other separate and distinct brake actuation, mechanisms (not shown in  FIG. 1 ). These various components of right electric brake subsystem architecture  104  are coupled together to operate as described above for left electric brake subsystem architecture  102 , however, the right-side processing is preferably independent of the left side processing. 
     In accordance with one embodiment of an electric brake system for an aircraft, an autobrake interlock mechanism or feature is provided to prevent inadvertent application of the wheel brakes. A system or a control mechanism in the electric brake system can be designed to implement such an autobrake interlock feature. For example, electric brake system  100  may be configured to support an electric autobrake interlock system. 
       FIG. 2  is a diagram that illustrates independent processing channels of an aircraft electric autobrake interlock system configured in accordance with an embodiment of the invention. In particular,  FIG. 2  depicts a left outboard power control, channel  216 , a left outboard autobrake command control channel  214 , a left inboard power control channel  220 , a left inboard autobrake command control channel  218 , a right inboard power control channel  228 , a right inboard autobrake command control, channel  226 , a right outboard power control channel  224 , and a right, outboard autobrake command control channel  222 . These processing channels may be realized in dm components of electric brake system  100 , e.g., the BSCUs, the EBACs, the power control subsystems, etc. In practice, each processing channel may include, without limitation: hardware components; digital logic elements; processing logic; circuit components; or any suitably configured architecture, arrangement, or feature. Moreover, each processing channel is suitably configured to perform the respective operations described herein. 
     For this example, the left processing channels correspond, to left-side processing of the electric brake system and the right processing channels correspond to right-side processing of the electric brake system. In this regard, the left and right processing power channels each may be fed by both left and right TRA sensor discrete (a binary signal with two possible states: high or low) data modules  202 / 206 . These TRA sensor discrete data modules  202 / 206  are configured to provide autobrake actuation data to the left and right power processing channels. In an embodiment of an electric brake system, both left and right TRA digital data (string of binary data) modules  210 / 205  provide autobrake actuation data for the left command processing channels. 
     Left outboard power control channel  216  and left outboard autobrake command control channel  214  cooperate to influence the operation of left outboard brake mechanisms  230  and in particular left outboard brake actuator(s). In this regard, left outboard power control channel  216  and left outboard autobrake command control channel  214  represent a control arrangement for the left outboard architecture of the electric autobrake system. For this example, left outboard power control channel  216  is suitably configured to provide the electric brake actuator operating power for left outboard brake mechanisms  230  using, e.g., a 130 volt power supply (not shown in  FIG. 2 ). Left outboard power control channel  216  functions to switch the left outboard brake mechanisms  230 . In one embodiment, left outboard power control channel  216  is suitably configured to regulate operating power for an EBAC coupled to left outboard brake mechanisms  230  and more specifically to the left outboard brake actuator(s)  231  as explained in detail in context of  FIG. 4  below. 
     Left outboard autobrake command control channel  214  is in parallel with left outboard power control channel  216 . Thus, it operates concurrently with and independent of left outboard power control channel  216 . Left outboard autobrake command control channel  214  is suitably configured to process brake mechanism control signals for left outboard brake mechanisms  230 . In one embodiment, left outboard autobrake command control channel  214  is configured to generate brake control signals for execution by an EBAC coupled to left outboard brake mechanisms  230  and more specifically to the left outboard brake actuator  231 . Notably, the brake control signals are effective only when left outboard brake actuator  231  is provided with adequate operating power. Accordingly, left outboard brake actuator  231  will be actuated if left outboard power control channel  216  enables operating power while the brake control signal commands the application of some clamping force. In contrast, left outboard brake actuator  231  will remain in a released (non-actuated) state if left outboard autobrake command control channel  214  disables operating power or if the brake control signal commands no clamping force. 
     In a preferred embodiment, the processing channels of the electric brake system are substantially (if not totally) independent of each other. For example, left outboard power control channel  216  is suitably configured to prevent actuation of left outboard brake mechanisms  230  and more specifically the left outboard brake actuator  231  independently of left outboard autobrake command control channel  214 . Likewise, left outboard autobrake command control channel  214  is suitably configured to prevent actuation of left outboard brake actuator  231  independently of left outboard power control channel  216 . Those processing channels receive different actuation data types via independent paths, and/or from separate data interfaces. The autobrake command processing channels  214 / 218 / 222 / 226  receive TRA digital data from TRA sensor data modules  210 / 203  (shown only for outboard autobrake command control channel  214  in  FIG. 2 ) and the power control channels  216 / 220 / 224 / 22 B each receive discrete data from TRA sensor discrete data modules  202 / 206 . In addition, the control arrangements for the left outboard, brake mechanisms  230  and in particular the left outboard brake actuator  231 , the left inboard brake mechanisms  232  and in particular the left inboard brake actuator  233 , the right inboard brake mechanisms  234  and in particular the right inboard brake actuator  235 , and the right outboard brake mechanisms  236  and in particular the right outboard brake actuator  237  are substantially (if not totally) independent of each other. For example, the four control arrangements may operate concurrently with, and independent of each other, or the left-side autobrake control architecture may operate concurrently with, and independent of, the right-side autobrake control architecture. The remaining three control arrangements depicted in  FIG. 2  operate as described, above for the left outboard processing channels. 
       FIG. 3  is a schematic representation of a portion of an aircraft electric brake system configured in accordance with an embodiment of the invention. In particular,  FIG. 3  depicts components of a left electric brake subsystem architecture  300  (as mentioned above, the right electric brake subsystem architecture has a similar structure). The electric brake system may also be configured as described above in the context of  FIG. 1  and  FIG. 2 . Accordingly, certain features, components, and functions of left electric brake subsystem architecture  301 ) will not be redundantly described here. 
     Left electric brake subsystem architecture  300  may include a BSCU  308 , an outboard electric brake power supply unit (EBPSU)  314 , an inboard EBPSU  328 , an outboard EBAC  316 , an inboard EBAC  330 , one or more outboard brake mechanisms  321  including at least one left outboard brake actuator  322 , and one or more inboard brake mechanisms  337  including at least one left inboard brake actuator  336 . Subsystem architecture  300  is suitably configured to receive or process autobrake actuation data from left TRA sensor digital data module  306 , right TRA sensor digital data module  307 , right TRA sensor discrete data module  302 , left TRA sensor discrete data module  304  or from other autobrake actuation sensor(s) data modules(s) not shown in  FIG. 3 . 
     BSCU  308  is generally configured as described above for BSCU  110 . BSCU  308  may include, an outboard autobrake interlock decision module  312 , an outboard autobrake command control module  310 , an inboard autobrake command control module  324 , and an inboard autobrake interlock decision module  326 . In this example, both left and right TRA sensor discrete data modules  302 / 304  make the TRA autobrake actuation, discrete data available to each outboard and inboard autobrake interlock decision module  312 / 326 . The left and right TRA sensor digital data modules  306 / 307  make the digital data available to each outboard and inboard autobrake command control modules  310 / 324 . 
     Each autobrake interlock decision, module  312 / 326  processes autobrake actuation data, and generates, in response to the autobrake actuation data, a respective enable/disable control signal for a power supply (e.g., an EBPSU) of a brake mechanism. Here, outboard interlock decision module  312  generates one enable/disable control signal for outboard EBPSU  314 , while inboard autobrake interlock decision module  326  generates another enable/disable control signal for inboard EBPSU  328 . If, for example, the autobrake actuation data, indicates an autobrake application condition, then each autobrake interlock decision module  312 / 326  will independently enable operating power to its respective brake mechanism(s). As used here, a “autobrake application condition” means any operating status, state, or configuration of the aircraft that is intended to result in the application of the autobrakes. For example, an antobrake application condition may result from; placing all throttle levers to an idle position; decreasing the aircraft acceleration below threshold acceleration, activation of an autobraking mode; or the like. On the other hand, if the autobrake actuation data does not indicate an antobrake application condition, then each autobrake interlock, decision modules  312 / 326  will independently disable operating power for its respective brake mechanism(s). This feature prevents inadvertent application of autobrake, which might otherwise occur if an erroneous autobraking command is propagated through left electric brake subsystem architecture  300 . 
     Each autobrake interlock decision module  312 / 326  may be realized in hardware using digital logic gates and related circuitry that processes the antobrake actuation data to generate the respective enable/disable control signals as explained in the context of  FIG. 4  below. In this regard, an enable/disable control signal may be a binary control signal having logic high and low states. The EBPSUs  314 / 328  respond to the respective enable/disable control signals in an appropriate manner. 
     Although, in this embodiment, left outboard autobrake command control  310  is suitably configured to generate respective brake actuation command signals in response to the autobrake actuation data, the autobrake command control  324  may also be suitably configured to generate respective brake actuation, command signals in response to the autobrake actuation. Here, outboard autobrake command, control  310  module generates brake actuation command signals for outboard EBAC  316 , which in turn controls outboard brake mechanism  321  and more specifically left outboard brake actuator  322 , while inboard autobrake command control  324  generates independent brake actuation command signals for inboard EBAC  330 , which in turn controls inboard brake mechanisms  337  and more specifically inboard brake actuator  336 . In practice, the brake mechanism, control signals influence the actuation, of the electric brake actuators in the brake mechanisms, (i.e., the percentage of full clamping force imparted, by the electric brake actuators). For example, a brake actuation command signal may command the electric brake actuators to release or apply no clamping force, it may command the electric brake actuators to apply full clamping force, or it may command the electric brake actuators to apply some intermediate clamping force. 
     Outboard autobrake interlock decision module  312  and outboard autobrake command control  310  operate concurrently (yet independently) on the autobrake actuation data. Likewise, inboard autobrake interlock decision, module  326  and inboard autobrake command control  324  operate concurrently (yet independently) on the autobrake actuation data. The segregation of processing architectures in this manner improves reliability and robustness of the electric autobrake interlock system. 
     In this embodiment, BSCU  308  controls EBPSUs  314 / 328  to enable/disable brake actuators  322 / 336  as needed. Each EBPSU  314 / 328  is configured to provide the operating voltage to its respective EBAC  316 / 330 . As mentioned above in connection with  FIG. 2 , the nominal EBAC operating voltage for this embodiment is about 130 volts. Thus, the EBPSUs can enable/disable the brake actuators by providing/removing this 130 volt supply voltage to/from the EBACs. 
     Outboard EBPSU  314  may employ an actuator power path  320  and an actuator command path  318 . Actuator power path  320  represents a structure, a channel, or an architecture configured to provide the operating power from outboard EBPSU to left outboard brake mechanisms  322 . Actuator command path  318  represents a structure, a channel, or an architecture configured to process and transfer autobrake control signals from BSCU  308  to outboard brake mechanisms  321 . Inboard EBAC  330  also includes similarly configured actuator command and actuator power paths. In this example, these four paths are separate and independent of each other. 
       FIG. 4  is a schematic representation of an electric autobrake interlock system for a portion (left outboard) of an aircraft electric brake subsystem architecture  400  configured in accordance with an embodiment of the invention. For this example deployment, subsystem architecture  400  generally includes: an autobrake actuator data generator system  438 , a power control processing channel  466 , an autobrake command processing channel  472 , a BSCU  446 , an EBAC  464  and a brake actuator  474 . Subsystem, architecture  400  may also be configured as described, above in the context of  FIGS. 1-3 . Accordingly, certain features, components, and functions of subsystem architecture  400  will not be redundantly described here. 
     Autobrake actuator data generator system  438  generally includes: a right throttle lever  402 , a left throttle lever  416 , a propulsion processing unit  405 , a right network interlace (RNI)  432  which includes a right TRA, data switch  436 , a left network interface (LNI)  433  which includes a left TRA data switch  442 . Subsystem architecture  400  is suitably configured to receive or process autobrake actuation data from right TRA sensor interfaces  406 / 408  via RNI  432 , autobrake actuation data from left TRA sensor interfaces  420 / 422  via a LNI  433 , and brake actuation command inputs from a network interface  439 . 
     Throttle levers  402 / 410  are configured to provide input to the propulsion processing unit  405  in order to provide input to electric brake subsystem  400  as explained in the context of  FIG. 1  above. 
     The propulsion, processing unit  405  is configured to provide the TRA inputs to the RNI/LNI  432 / 433  via the electric airplane network bus  430 . Power to the brakes to enable autobrake is desired whenever the TRA sensors  405 / 407  and  410 / 421  values indicate idle (TRA values are below a threshold value). Otherwise, power is not provided to the brakes in a manner to interlock/disable the antobrake. 
     RNI/LNI  432 / 433  provide left TRA sensors values and right TRA sensors values to the BSCU  446 . To protect against inadvertent braking (i.e., data, error), each RNI/LNI  432 / 433  receives two digital TEA positions form the propulsion unit  405 . For example, right RNI  432  receives redundant right TRA digital values. The right RNI  432  gateways the first valid available value out of the redundant copies of right TRA digital values and the LNI  433  gateways the first valid available value out of the redundant copies of left TRA digital values. Each RNI/LNI  432 / 433  then performs a digital to analog conversion (not shown in  FIG. 4 ) based on a digital discrete signal indicating whether their respective throttle is at “Idle” or “Advanced” to obtain an analog discrete output signal (high/low) suitable for operation of the power control processing channel  466  and in particular BSCU  446 . The LNI/RNI provide the signal high/low values of the left and right TRAs to the BSCU  446  and in particular to the autobrake interlock decision module  448 . 
     A TRA signal high value is provided to the power control processing channel  466  via TRA data switches  436 / 442 . Notably TRA data switches  436 / 442  are shown in an open position in an example embodiment of  FIG. 4  indicating TRA sensor values are not idle. When TRA sensor values indicate idle, TRA data witches  436 / 442  close. In this regard, based upon the TRA sensor values idle/not idle; the power processing channel controls power supply to the brakes as explained below. 
     The power control processing channel  466  may generally include an autobrake interlock decision module  448  and an EBPSU  462 . The power control processing channel  466  may be realized in the components of electric brake subsystem architecture  400 , e.g., the BSCU  446 , and the EBAC  464 . 
     The autobrake interlock decision module  448  may be realized in hardware using digital logic gates and related circuitry that processes the autobrake actuation data to generate the respective enable/disable control signals. The autobrake interlock decision module  448  provides an enable/disable power control signal to the EBPSU  462  based upon TRA sensor values. In this example embodiment the autobrake interlock decision module  448  includes an OR gate  452 , an autobrake enable/disable module  460  and an enable/disable power control signal  458 . The EBPSU  462  responds to the respective enable/disable power control signal  458  in a manner described herein. The autobrake interlock decision module  448  receives two input signals  454 / 456  (logic high or logic low) from the RNI/LNI  432 / 433  as explained above. Input signal  454  conveys whether the left thrust lever  416  is “Advanced” or “idle” and the input signal  456  conveys whether the right thrust lever  402  is “Advanced” or “idle”. At least one of the input signals  454 / 456  have to indicate “Idle” in order for the BSCU  446  and in particular autobrake enable/disable module  460  to output a power enable signal  438  to the EBPSU  462  to activate the EBAC  464  (in this regard, availability of autobrake function is ensured in one engine). Otherwise, the autobrake enable/disable module  460  outputs a power disable signal  458  to the EBPSU  462  to prevent actuation power from reaching the EBAC and in particular to disable the brake actuator  474 . In this regard, the power control processing channel  466  provides the necessary architecture to protect against any single failure that could result in inadvertent autobrake application independent of autobrake command processing channel  472 . 
     The autobrake command processing channel  472  may generally include an autobrake command control module  468 . The autobrake command processing channel  472  may be realized in the components of electric brake subsystem architecture  400 , e.g., the BSCU  446 , and the EBAC  464 . 
     The autobrake command control module  468 , independently (yet concurrently) from the autobrake interlock decision module  448 , receives autobrake actuation data from the digital network interface  439 , determines whether the autobrake actuation conditions are met such as no braking system faults and thrust levers in the idle position and generates brake control signals in response to the received autobrake actuation data. If the autobrake actuation data does not indicate that autobrake application conditions are met then the antobrake command control module  468  will generate about 0 % clamping force command (i.e., no brake application). Thus, if the autobrake is commanded inadvertently by autobrake command control module  468 , and the autobrake interlock decision module  448  outputs a power disable signal, the autobrake command control module  468  does not activate the brakes. 
     Briefly, the electric brake subsystem architecture  400  makes use of right TRA data and left TRA data made available on the airplane network  430  to produce autobrake interlock enable/disable control signals in a manner described above. In this regard, power control processing channel  466  and autobrake command processing channel  472  operate concurrently (yet independently) to enable/disable autobrake application in response to the autobrake actuation data using a process explained below. 
       FIG. 5  is a flow chart that illustrates an electric autobrake interlock process  500  suitable for use in connection with an aircraft electric brake system. The various tasks performed in connection with process  500  may be performed by software, hardware, firmware, or any combination thereof. For illustrative purposes, the following description of process  500  may refer to elements mentioned above in connection with  FIGS. 1-4 . In embodiments of the invention, portions of process  500  may be performed by different elements of the described system. e.g., a BSCU, an EBAC, an EBPSU, or the like. It should he appreciated that process  500  may include any number of additional or alterative tasks, the tasks shown in  FIG. 5  need not be performed in the illustrated order, and process  500  may be incorporated into a more comprehensive procedure or process having additional functionality not described in detail herein. 
     In connection with electric autobrake interlock process  500 , the electric autobrake system receives and processes autobrake actuation data (task  502 ) in a continuous or rapidly sampled manner.  FIG. 5  depicts two processing branches that occur concurrently during process  500 . A power interlock processing branch  504  is shown on the left side of  FIG. 5 , and a autobrake command processing branch  506  is shown on the right side of  FIG. 5 . Power interlock processing branch  504  analyzes the autobrake actuation data and in particular TRA sensor discrete data to determine whether it indicates an autobrake application condition (query task  508 ). If so, then process  500  generates a “power supply enable” control signal (task  510 ) that enables a power supply for the brake mechanisms and in particular for the electric brake actuators (task  512 ). In other words, the brake mechanisms will be able to respond to brake control signals. In this example, process  500  controls an EBPSU to switch its operating power supply on such that the operating power is provided to the EBACs coupled to the EBPSU. In turn, the EBACs provide the operating power to the brake mechanisms and particular to the electric brake actuators. 
     If query task  508  does not indicate an autobrake application condition, then electric autobrake interlock process  500  will regulate the operating power for the brake mechanisms to disable the brake actuators. In this regard, process  500  generates a “power supply disable” control signal (task  514 ) that disables the power supply for the brake mechanisms (as a result, process  500  removes operating power from the brake actuators—task  516 ). In other words, as long as the autobrake application condition is not met, the brake actuators will not be able to respond to any brake control signals because they lack sufficient operating power. In this example, process  500  controls an EBPSU to switch its operating power supply off to remove the operating power from the EBACs coupled to the EBPSU. In turn, the EBACs no longer provide operating power to the brake mechanisms. 
     Concurrently with (and independent of) power interlock processing branch  504 , autobrake command processing branch  506  processes autobrake actuation data and in particular TRA digital data (task  518 ). If the autobrake actuation data indicate an autobrake application condition (query task  520 ), then process  500  generates a brake actuation control command in response to the autobrake actuation data (task  522 ) in an attempt to control actuation of the brake mechanism. In other words, the brake actuation control command will command the brake actuators to actuate by a designated amount, resulting in some brake clamping force. In other words, the brake actuation control command controls the brake mechanisms and in particular the brake actuators to release or apply no clamping force. If the autobrake actuation data does not indicate an autobrake application condition (query task  520 ), the brake actuation control command will not be generated in an attempt to prevent actuation of the brake actuators (task  524 ). As mentioned above, these brake actuation commands will be ineffective if power interlock processing branch  504  has removed operating power from the brake mechanisms. In other words process  500  provides actuation control for the brake mechanism and in particular for the electric brake actuators if the following two actions happen: the operating power is provided to enable the electric brake actuators, and the brake actuation control is commanded in response to the autobrake actuation data indicating an autobrake application condition (reference number  256 ). 
     In summary, an electric autobrake interlock system as described herein utilizes an autobrake control architecture having a hardware-based autobrake interlock path that provides an on/off control for the operating power of the brake mechanisms and in particular the brake actuators, and a software-based, processing path that generates the brake actuation control commands for the brake mechanisms. With this approach, the probability of uncommanded autobrake application is the probability of both the hardware interlock failing and the software control failing, which is very low in practical deployments. The only components that are in common are the autobrake actuator motors and motor control (unlikely to command on their own) and the source of digital TRA data. 
     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.