Patent Description:
Aircraft often include one or more landing gear that comprise one or more wheels. Each wheel may have a brake that is operatively coupled to the wheel to slow the wheel, and hence the aircraft, during, for example, landing or a rejected takeoff. Aircraft may employ hydraulic or electromechanical braking systems. Some aircraft brake systems adjust the compression of friction disks by controlling a servo valve to adjust the pressure of a hydraulic actuator. Other aircraft brake systems adjust the compression of the friction disks by controlling electro-mechanical actuators. Aircraft brake control systems receive input signal(s) indicating a desired braking force or braking torque and may transmit a signal to a brake controller. The signal may direct a brake actuator or brake valve to produce a braking force/torque. However, a brake control system may malfunction, and can result in un-commanded brake application actuated to one or more wheels during takeoff or landing. It is desirable to safeguard and reduce instances of un-intended command actions of brake application to one or more wheels of the aircraft when take-off power is applied to the engines of the aircraft. <CIT> describes a controller for an electromechanical braking system.

In various embodiments, a brake system is described. The brake system includes a primary brake control unit; and an alternate brake control unit; in response to the primary brake control unit placed in an active mode, the primary brake control unit is configured to separately send data on a set of channels to control brake operation of at least one outboard brake and at least one inboard brake while the alternate brake control unit is configured to receive data during the brake operation to monitor brake temperature on another set of channels coupled to a plurality of brake temperature sensors associated with the at least one outboard brake and the at least one inboard brake.

In various embodiments, the data on the set of channels to control brake operation and the data to monitor brake temperature are separately sent and received on different channels by the primary brake control unit and the alternate brake control unit.

In various embodiments, the brake system further includes in response to the alternate brake control unit placed in the active mode, the alternate brake control unit is configured to separately send data on the set of channels to control brake operation of at least one outboard brake while configured to monitor brake temperature on another set of channels coupled to the plurality of brake temperature sensors associated with at least one outboard brake and the at least one inboard brake.

In various embodiments, the primary brake control unit is configured for takeoff of an aircraft in the active mode to send data on the set of channels to the outboard brake while the alternate brake control unit is configured in the takeoff of the aircraft in a standby mode to receive data separately on another set of channels to monitor temperature of at least the outboard brake and the inboard brake during the takeoff of the aircraft.

In various embodiments, the alternate brake control unit is configured for landing of the aircraft in the active mode to send data on the set of channels to the outboard brake and to receive data separately on another set of channels to monitor the temperature of at least the outboard brake and the inboard brake during the landing of the aircraft.

In various embodiments, the primary brake control unit and the alternate brake control unit are configured to switch back and forth between the active mode for a plurality of aircraft operations to control the brake operation with alternate brake control unit configured to monitor the brake temperature.

In various embodiments, the primary brake control unit is configured to function independent of the alternate brake control unit during the takeoff of the aircraft to prevent a common failure from occurring in the primary brake control unit and the alternate brake control unit resulting in an un-commanded brake control action on at least one wheel of the aircraft during the takeoff and loss of brake temperature monitoring on at least one wheel of the aircraft during the takeoff.

In various embodiments, a brake system is provided. The brake system includes at least one inboard brake; at least one outboard brake; a plurality of brake temperature sensors; a primary brake control unit; and an alternate brake control unit; wherein the primary brake control unit is configured in a first mode, to separately send data on a set of channels to control brake operation of at least one outboard brake and at least one an inboard brake while the alternate brake control unit is configured, in a second mode, to receive data during the brake operation to monitor brake temperature on a different set of channels coupled to the plurality of brake temperature sensors associated with at least one outboard brake and the at least one inboard brake.

In various embodiments, the data on the set of channels to control brake operation and the data to monitor brake temperature is sent and received on a plurality of channels to segregate control and monitor functions between the primary brake control unit and the alternate brake control unit in controlling the brake operation and monitoring the brake temperature.

In various embodiments, the alternate brake control unit is configured in the first mode to send data on the set of channels to control brake operation of the at least one outboard brake and at least one inboard brake and to monitor brake temperature on the different set of channels coupled to the plurality of brake temperature sensors associated with at least one outboard brake and at least one inboard brake.

In various embodiments, the primary brake control unit and the alternate brake control unit are configured vice versa in either the first mode or the second mode to send data on the set of channels to control brake operation of at least one outboard brake and at least one an inboard brake, while the alternate brake control unit is configured to monitor brake temperature on the different set of channels coupled to the plurality of brake temperature sensors associated with at least one outboard brake and at least one inboard brake.

In various embodiments, the primary brake control unit is configured for a takeoff flight phase in the first mode to send data on the set of channels to the outboard brake and the inboard brake while the alternate brake control unit is configured in the takeoff flight phase in the second mode to receive data separately on the different set of channels to monitor the temperature of at least the outboard brake and the inboard brake during the takeoff flight phase.

In various embodiments, the alternate brake control unit is configured for a landing flight phase in the first mode to send data on the set of channels to the outboard brake and the inboard brake and to monitor the temperature of at least the outboard brake and the inboard brake during the landing flight phase.

In various embodiments, the primary brake control unit and the alternate brake control unit are configured to alternate between the first mode and the second mode for a plurality of aircraft operations to independently perform functions of controlling the brake operation while the alternate brake control unit is configured for monitoring the brake temperature.

In various embodiments, the primary brake control unit is configured to function independent of the function of the alternate brake control unit during multiple flight phases to control brake operation and to prevent a common failure from occurring in the primary brake control unit and the alternate brake control unit resulting in an un-commanded brake control action on at least one wheel of an aircraft during takeoff and loss of brake temperature monitoring on at least one wheel of the aircraft during the takeoff.

In various embodiments, the multiple flight phases comprise at least a taxi operation, a takeoff operation, and a landing operation of the aircraft.

In various embodiments, a method of controlling a brake system is provided. The method includes receiving a first status for a primary brake control unit; receiving a second status for an alternate brake control unit wherein the second status is dependent on the first status; determining whether the primary brake control unit based on the first status is configured in a state to perform functions of controlling brake operations; determining whether the alternate brake control unit based on the second status is configured in another state to perform functions of controlling brake operations with a function of monitoring brake temperatures; and activating the primary brake control unit, and the alternate brake control unit in either state to segregate performing of the functions of the primary brake control unit and the alternate brake control unit for controlling brake operations with the alternate brake control unit performing the function of monitoring brake temperatures.

In various embodiments, segregating of the functions prevents propagating of a failure mode between both the primary brake control unit and the alternate brake control unit resulting in an un-commanded brake control action on at least one wheel of an aircraft during a takeoff and loss of brake temperature monitoring on the at least one wheel of the aircraft during the takeoff.

In various embodiments, the first status comprises at least a takeoff status of the aircraft.

In various embodiments, the first status comprises at least a landing status of the aircraft.

The subject matter of the present invention is a brake system according to claim <NUM> and a method of controlling a brake system according to claim <NUM>. Further preferred embodiments are disclosed in the dependent claims.

The following detailed description of various embodiments herein refers to the drawings, which show various embodiments by way of illustration. While these various embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, it should be understood that other embodiments may be realized and that changes may be made without departing from the invention. Thus, the detailed description herein is presented for illustration only and not of limitation. Any reference to singular includes plural embodiments, and any reference to more than one component or step may include a singular embodiment or step. Further, all ranges may include upper and lower values and all ranges and ratio limits disclosed may be combined.

As used herein, a first component that is "radially outward" of a second component means that the first component is positioned at a greater distance away from a common axis (e.g., a rotational axis of a wheel assembly) than the second component. A first component that is "radially inward" of a second component means that the first component is positioned closer to the common axis than the second component. In the case of components that rotate about a common axis, a first component that is radially inward of a second component rotates through a circumferentially shorter path than the second component. As used herein, "distal" refers to the direction outward, or generally, away from a reference component. As used herein, "proximal" and/or "proximate" refer to a direction inward, or generally, towards the reference component.

Aircraft architecture is functionally interdependent and is a system-of-systems configuration where systems interact with each other and are dependent upon each another to perform operations. In electric brakes, a brake controller (or controller) is coupled to one or more electromechanical actuator controllers (EMACs) for a brake, which drives one or more electromechanical brake actuators. The brake controller may be in communication with a brake pedal, and thus may control the EMACs in accordance with pilot/copilot braking commands. In various aircraft, other means are used to compress a brake disk stack. A brake controller may comprise a processor and a tangible, non-transitory memory. The brake controller may comprise one or more logic modules that implement brake logic. In various embodiments, the brake controller may comprise other electrical devices to implement brake logic.

In various embodiments, a brake control system is configured with a primary and alternate architecture which are two independently operated brake systems. Both systems functions in opposite modes, when one system is active, for example the primary system, the alternate system is in stand-by mode (or inactive). If the primary system suddenly fails, then braking responsibility transfers to the alternate system.

In various embodiments, the main brake control function is segregated from the Brake Temperature Monitoring (BTM) function in order to prevent an un-commanded brake action to one or more wheels during takeoff or the un-commanded brake action initiated in combination with a loss of brake temperature monitoring that can occur based upon various common failure modes or a single development error in the system.

Referring to <FIG> illustrates a diagram of an aircraft <NUM> on a runway <NUM> with landing gear of a plurality of wheels in accordance with various embodiments. The aircraft <NUM> may comprise right landing gear <NUM>a, left landing gear <NUM>b, and nose landing gear <NUM>. The nose landing gear <NUM> is located under the nose of aircraft <NUM> and may not include a brake. Each landing gear is illustrated in <FIG>, for example, as having two wheels. For example, right landing gear <NUM>a may comprise a plurality of wheels, such as a right outboard (ROB) wheel <NUM> and a right inboard (RIB) wheel <NUM>. Left landing gear <NUM>b may comprise a plurality of wheels, such as a left outboard (LOB) wheel <NUM> and a left inboard (LIB) wheel <NUM>. In various embodiments, aircraft <NUM> may comprise any number of landing gears and each landing gear may comprise any number of wheels. The landing gear supports the aircraft <NUM> when it is not flying, allowing the aircraft <NUM> to taxi, takeoff, and land without incurring damage. While the invention refers to a single landing gear configuration, the invention should not be construed as limited to this configuration and contemplates any number or multiple landing gear configurations.

In various embodiments, various critical safety objectives are accomplished by brake control systems configured with the landing gear of the aircraft <NUM> and include multiple scenarios (deemed catastrophic) of the total loss of braking operation by the aircraft brakes, un-commanded brake application on at least two wheels during takeoff, and the un-commanded brake application on one or more wheels during takeoff/landing combined with a loss of brake temperature monitoring.

In various embodiments, the brake control system is configured to comply with various safety requirements, for example those defined in by the U. Federal Aviation Administration Advisory Circular ("AC")/AMJ <NUM> ARSENAL version. The Section <NUM>(b) provides requirements for a (logical and acceptable inverse) relationship between the probability and the severity of certain failure conditions. In various embodiments, SAE International's SAE ARP4761 for compliance maintains the main brake control function shall be segregated from the Parking Brake function up to the brake shuttle valves interface in order to reduce the common modes which may cause total loss of brakes; segregated from the Nose Wheel Steering Control function in order to prevent that any common mode may result in loss of directional control on ground; segregated from the Landing Gear Control function in order to prevent that any common mode may result in loss or erroneous wheel speed and air/ground data, and segregated from the Brake Temperature Monitoring function in order to prevent that a common failure mode or single development error may result in un-commanded brake application on any wheel during takeoff combined with loss of brake temperature monitoring.

Referring to <FIG> and <FIG>, the aircraft <NUM> may include a brake system <NUM>, which may be applied to any wheel of the landing gear. The brake system <NUM> may comprise a brake control system of aircraft <NUM>. The brake system <NUM> of aircraft <NUM> may be a collection of subsystems that produce output signals for controlling the braking force and/or torque applied to each of wheels <NUM>, <NUM>, <NUM>, <NUM>. The brake system <NUM> may communicate with the brakes of the right landing gear <NUM>a and the left landing gear 14b. The right landing gear <NUM> a may include a ROB brake <NUM> and a RIB brake <NUM> coupled to ROB wheel <NUM> and RIB wheel <NUM>, respectively. ROB brake <NUM> and RIB brake <NUM> may be mounted to ROB wheel <NUM> and RIB wheel <NUM>, respectively, to apply and release braking force on each respective wheel. The left landing gear 14b may include an LOB brake <NUM> and a LIB brake <NUM> coupled to LOB wheel <NUM> and LIB wheel <NUM>, respectively. LOB brake <NUM> and LIB brake <NUM> may be mounted to LOB wheel <NUM> and LIB wheel <NUM>, respectively, to apply and release braking force on each respective wheel. The RIB brake <NUM> and LIB brake <NUM> may be referred to, collectively, as inboard brakes <NUM>. The ROB brake <NUM> and LOB brake <NUM> may be referred to, collectively, as outboard brakes <NUM>.

Referring to <FIG>, the brake system <NUM> is shown schematically having architecture in accordance with various embodiments. The brake system <NUM> may include at least one upper-level controller, or brake control unit (BCU) <NUM>, for providing overall control of the braking system. In various embodiments, as described below, BCU <NUM> comprises a primary BCU and an alternate BCU. The BCU <NUM> may interpret input commands or input signals <NUM> from the aircraft cockpit controls and avionics and may issue braking force commands to inboard brakes <NUM> and outboard brakes <NUM>. In various embodiments, the brake system <NUM> may include a primary inboard (PIB) channel <NUM>, a primary outboard (POB) channel <NUM>, an alternate inboard (SIB) channel <NUM> and an alternate outboard (SOB) channel <NUM>.

Each of the PIB channel <NUM> and SIB channel <NUM> may be coupled to or in electrical communication with the inboard brakes <NUM>. The inboard brakes <NUM> may be configured to receive a command through either of PIB channel <NUM> or SIB channel <NUM>, such that inboard brakes <NUM> may be controlled by PIB channel <NUM> or SIB channel <NUM>. Each of POB channel <NUM> and SOB channel <NUM> may be coupled to or in electrical communication with outboard brakes <NUM>. The outboard brakes <NUM> may be configured to receive a command through either of POB channel <NUM> or SOB channel <NUM>, such that outboard brakes <NUM> may be controlled by POB channel <NUM> or SOB channel <NUM>.

The PIB channel <NUM> may further include dual redundant communication channels. For example, PIB channel <NUM> may include a first PIB channel <NUM>-<NUM> and a second PIB channel <NUM>-<NUM>. POB channel <NUM> may further include dual redundant communication channels, such that POB channel <NUM> includes a first POB channel <NUM>-<NUM> and a second POB channel <NUM>-<NUM>. SIB channel <NUM> may further include dual redundant communication channels, such that SIB channel <NUM> includes a first SIB channel <NUM>-<NUM> and a second SIB channel <NUM>-<NUM>. SOB channel <NUM> may further include dual redundant communication channels, such that SOB channel <NUM> includes a first SOB channel <NUM>-<NUM> and a second SOB channel <NUM>-<NUM>.

Referring to <FIG> illustrates a diagram of the brake control system and brake temperature system control architecture for segregated monitoring by the alternate brake control unit which functions separately from the primary brake control unit to monitor the brake temperature of the inboard and outboard brakes of the aircraft in accordance with various embodiments. In <FIG>, the control diagram <NUM> illustrates a state in which the primary brake control unit (BCU) <NUM> is siloed off or segregated from the alternate brake control unit (BCU) <NUM>. The primary BCU <NUM> is configured with multiple channels of an outboard channel system <NUM> and an inboard channel system <NUM> for controlling the brake operations of the inboard and outboard brake sets. In that regard, in various embodiments, primary BCU <NUM> is in electronic communication with POB channel <NUM> and PIB channel <NUM> while alternate BCU <NUM> is in electronic communication with SOB channel <NUM> and SIB channel <NUM>, with momentary reference to <FIG>.

In an active mode when the aircraft is in a takeoff operational state such as when takeoff power is being applied to the engines or during a taxing operation for takeoff, the primary BCU <NUM> is configured to control the inboard and outboard brake sets while the alternate BCU <NUM> is configured to monitor the inboard and outboard brake set temperatures. Thus, the primary BCU <NUM> is in an active state and the alternate BCU <NUM> is in a standby state. In various embodiments, the alternate BCU <NUM> is configured with an inboard channel system <NUM> and an outboard channel system <NUM>. The inboard channel system <NUM> is coupled to brake temperature sensors in separate channels to a left inboard (LIB) brake temperature sensor <NUM> and on another channel to the right inboard (RIB) brake temperature sensor <NUM>. The outboard channel system <NUM> is similarly coupled on separate channels to the right outboard (ROB) brake temperature sensor (BTS) <NUM> and the left outboard (LOB) brake temperature sensor (BTS) <NUM>. The alternate BCU <NUM> in this standby state, with the primary BCU <NUM> in an active state, receives temperature data from multiple brake temperature sensors associated with sets of inboard and outboard brake sets, e.g., LIB sensor <NUM>, RIB sensor <NUM>, ROB sensor <NUM>, and/or LOB sensor <NUM>. To avoid latent failures in each system, the primary and alternate braking systems are alternated in the landing phase. For example, in the takeoff flight phase, the primary BCU <NUM> is placed in an active state to control the brake operation, and the alternate BCU <NUM> is placed in the standby state (or another state) to monitor the temperature of the brakes during the active brake operations. In contrast, whether the primary BCU <NUM> or the alternate BCU <NUM> is in the active state during a landing phase is determined by which of the primary BCU <NUM> or the alternate BCU <NUM> was in the active state during the prior landing of the aircraft. For instance, if the primary BCU <NUM> was in the active state during the previous landing of the aircraft, in the next landing phase, the alternate BCU <NUM> is placed in the active state to control brake operations and to monitor brake temperatures while the primary BCU <NUM> is placed in the standby. Similarly, if the alternate BCU <NUM> was in the active state during the previous landing of the aircraft, in the next landing phase, the primary BCU <NUM> is placed in the active state to control brake operations. Thus, the alternating of active control between the primary BCU <NUM> and the alternate BCU <NUM> is determined based on which unit was active during the prior landing of the aircraft.

In various embodiments, the primary BCU <NUM> is always kept in an active state during the takeoff flight phase to control brake operation while the alternate BCU <NUM> is kept in a different state (e.g., the standby state or mode) to monitor temperature of the inboard and outboard brakes and to receive temperature data from the braking temperature sensors associated with each of the brake units (i.e., the inboard and outboard brake sets). In various embodiments, the primary BCU <NUM> is kept in the active state during the takeoff phase unless the primary BCU <NUM> fails during the takeoff phase, in which case, the alternate BCU <NUM> is changed to the active state and becomes the active braking system (and performs both the braking control and temperature monitoring). This configuration of the primary BCU <NUM> and the alternate BCU <NUM> provides separation between each braking system and enables each braking system to function independently in the tasks assigned for brake control with the alternate BCU <NUM> always performing the brake temperature monitoring.

In various embodiments, the segregated channel architecture enables both braking systems, the primary and alternate braking systems to meet the safety requirements of a brake control system that separates (or requires segregation) the brake temperature monitoring system during the takeoff phase of the aircraft operation from the braking control operation.

In various embodiments, the separate channel configuration of the primary and alternate brake control units prevents common fault propagation between both braking systems and the un-commanded brake application on at least one wheel (i.e., any wheel) of the aircraft during takeoff/landing combined with a loss of brake temperature monitoring without the need to have a separate brake temperature monitoring system. Specifically, the alternate BCU <NUM> provides the brake temperature monitoring system separate from the active braking system during the takeoff phase of the aircraft operation (i.e., the alternate BCU <NUM> is a separate system for temperature monitoring and the stand-by braking system) while the primary BCU <NUM> is the active braking system during the takeoff phase of the aircraft operation.

In various embodiments, the active braking controller (i.e., the primary BCU <NUM>) and the brake temperature monitoring system (i.e., the alternate BCU <NUM>) communicate between each other to resolve status conflicts (i.e., the BCUs communicate via digital communications and resolve through the communications the proper status of each other). This communication link is represented by electronic communication line <NUM>, which may comprise one or more wired or wireless interfaces with allow BCU <NUM> and BCU <NUM> to be in logical communication. If the primary BCU <NUM> fails as a result of at least one failure, the alternate BCU320 will become active because it is standing by in a fully functional state.

In various embodiments, the brake temperature sensors (i.e., the right outboard (ROB) brake temperature sensor (BTS) <NUM> and the left outboard (LOB) brake temperature sensor (BTS) <NUM>) comprise an assembly of k-thermo-couple sensors which are wired to or otherwise coupled with the alternate BCU <NUM> which acts as a monitoring system for brake temperature during a takeoff and also in case of a rejected takeoff (RTO) event or other similar event. In various embodiments, by default, the primary BCU <NUM> is in an active state, and the brake temperature sensors are configured in a single channel operation to be connected to the alternate braking systems, i.e., alternate BCU <NUM>. As discussed above, in various embodiments, during the landing flight phases, the primary BCU0 <NUM> and alternate BCU <NUM> alternate between braking control, with the alternate braking system always performing temperature monitoring. This alternating between the primary BCU <NUM> and alternate BCU <NUM> is done to minimize latent failures during the landing phase of the aircraft as, if one of the BCUs <NUM> and <NUM> were to fail, the other would take control in this alternating configuration. In various embodiments, the primary BCU <NUM> and alternate BCU <NUM> will determine based on the previous landing which brake system should be active during a current landing, the primary braking system or the alternate braking. In various embodiments, the use of primary BCU <NUM> and alternate BCU <NUM> described herein provides for independent operation of the primary and alternate systems, which serves to prevent loss of more than one braking system due to a single failure in braking system.

In various embodiments, during an approach flight phase, the primary BCU <NUM> and alternate BCU <NUM> determine, based on a landing history of the aircraft, which brake system should be active, the primary BCU <NUM> or the alternate BCU <NUM>. If the alternate BCU <NUM> is the active system during landing (i.e., the system to actively control brake functions), the alternate BCU <NUM> is still configured and coupled to the brake temperature sensors <NUM>, <NUM>, <NUM>, and <NUM> providing temperature data.

Referring now to <FIG> and <FIG>, an aircraft braking system <NUM> is illustrated in conjunction with an outboard wheel <NUM> and an inboard wheel <NUM> on each of a port side and a starboard side of an aircraft. A separate brake <NUM> is provided for each of the outboard wheels <NUM> and the inboard wheels <NUM>. A hydraulic system pressure source A <NUM> is fluidly connected with an outboard dual brake control valve module <NUM>, which is in turn fluidly connected with the brake <NUM> for each of the outboard wheels <NUM> and an inboard dual brake control valve module <NUM>, which is in turn fluidly connected with the brake <NUM> for each of the inboard wheels <NUM>. The aircraft braking system <NUM> further includes a hydraulic system A return <NUM>. Similarly, a hydraulic system pressure source B <NUM> is fluidly connected with an outboard dual brake control valve module <NUM>, which is in turn fluidly connected with the brake <NUM> for each of the outboard wheels <NUM> and an inboard dual brake control valve module <NUM> which is in turn fluidly connected with the brake <NUM> for each of the inboard wheels <NUM>. The aircraft braking system <NUM> further includes a hydraulic system B return <NUM>. The aircraft braking system further includes a plurality of hydraulic fuses <NUM>, pressure transducers <NUM>, shuttle valves <NUM>, a <NUM> VDC (DC voltage) bus" <NUM>, and a <NUM> VDC bus" <NUM>.

The above-noted brake control valve modules <NUM>, <NUM>, <NUM>, <NUM> may each utilize one or more servo valves, one or more shut-off valves, or the like. The brake control valve modules <NUM>, <NUM>, <NUM>, <NUM> are disposed in the flow path of their corresponding hydraulic system pressure source <NUM>, <NUM>. The shuttle valve(s) for each of the outboard dual brake control valve module <NUM> and the inboard dual brake control valve module <NUM> is disposed downstream of its corresponding servo valve(s) and the corresponding brake <NUM>. Similarly, the shuttle valve(s) for each of the outboard dual brake control valve module <NUM> and the inboard dual brake control valve module <NUM> is disposed downstream of its corresponding servo valve(s) and the corresponding brake <NUM>.

The aircraft braking system <NUM> of <FIG> further includes a first or pilot pedal pair <NUM> and a second/co-pilot pedal pair <NUM>. The first pedal pair <NUM> includes a first (e.g., left) pedal <NUM> and a second (e.g., right) pedal <NUM>. A first pedal position sensor 412a and a second pedal position sensor 412b monitor the position of the first pedal <NUM> (e.g., displacement of the first pedal <NUM>). Similarly, a first pedal position sensor 414a and a second pedal position sensor 414b monitor the position of the second pedal <NUM> (e.g., displacement of the second pedal <NUM>). The second pedal pair <NUM> includes a first (e.g., left) pedal <NUM> and a second (e.g., right) pedal <NUM>. A first pedal position sensor 422a and a second pedal position sensor 422b monitor the position of the first pedal <NUM> (e.g., displacement of the first pedal <NUM>). Similarly, a first pedal position sensor 424a and a second pedal position sensor 424b monitor the position of the second pedal <NUM> (e.g., displacement of the second pedal <NUM>). Each of the pedal position sensors 412a, 412b, 414a, <NUM> b, 422a, 422b, and <NUM> a, 424b may be in the form of a linear variable differential transformer (LVDT).

The aircraft braking system <NUM> utilizes both a first (e.g., primary) brake control unit (BCU) <NUM> and a second (e.g., alternate, or alternate) BCU <NUM>. The first BCU <NUM> and second BCU <NUM> may be substantially similar to the primary BCU <NUM> and alternate BCU <NUM> discussed above in connection with <FIG>. The first BCU <NUM> includes an inboard brake control card (BCC) <NUM> and an outboard BCC <NUM>. Similarly, the second BCU <NUM> includes an inboard BCC <NUM> and an outboard BCC <NUM>. <FIG> illustrate: <NUM>) an output of the first pedal position sensor 412a for the first pedal <NUM> (first pedal pair <NUM>) is provided to the outboard BCC <NUM> of the first BCU <NUM>; <NUM>) an output of the second pedal position sensor 412b for the first pedal <NUM> (first pedal pair <NUM>) is provided to the inboard BCC <NUM> of the second BCU <NUM>; <NUM>) an output of the first pedal position sensor 414a for the second pedal <NUM> (first pedal pair <NUM>) is provided to the inboard BCC <NUM> of the first BCU <NUM>; <NUM>) an output of the second pedal position sensor 414b for the second pedal <NUM> (first pedal pair <NUM>) is provided to the outboard BCC <NUM> of the second BCU <NUM>; <NUM>) an output of the first pedal position sensor 422a for the first pedal <NUM> (second pedal pair <NUM>) is provided to the outboard BCC <NUM> of the first BCU <NUM>; <NUM>) an output of the second pedal position sensor 422b for the first pedal <NUM> (second pedal pair <NUM>) is provided to the inboard BCC <NUM> of the second BCU <NUM>; <NUM>) an output of the first pedal position sensor 424a for the second pedal <NUM> (second pedal pair <NUM>) is provided to the inboard BCC <NUM> of the first BCU <NUM>; and <NUM>) an output of the second pedal position sensor 424b for the second pedal <NUM> (second pedal pair <NUM>) is provided to the outboard BCC <NUM> of the second BCU <NUM>.

In various embodiments, the first and second BCU <NUM>, <NUM> may comprise various components to aid in selecting an inboard or outboard brake for a respective landing gear and determining a brake pressure to supply to the respective brake.

For example, the first and second BCU <NUM>, <NUM> may each comprise a computing device (e.g., a processor) and an associated memory. The processor may comprise any suitable processor, such as, for example, a general-purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof. The memory may comprise an article of manufacture including a tangible, non-transitory computer-readable storage medium having instructions stored thereon that, in response to execution by the computing device (e.g., processor), cause the computing device to perform various methods, as discussed further herein.

The first (primary) BCU <NUM> is coupled to the channel network 432a to control operation of the brakes via brake control valve modules for the inboard and outboard brakes. The second (alternate) BCU <NUM> is coupled via the channel network 432b to the plurality of brake temperature sensors <NUM> to monitor the brake temperatures of the sets of inboard and outboard brakes (i.e., brakes <NUM>).

The channel network 432b provides temperature data to the second BCU <NUM> to monitor brake <NUM> temperatures during control and operation of the brakes by the first BCU <NUM>. Therefore, each braking control unit, i.e., the first BCU <NUM> and the second BCU <NUM>, is functioning independently with the dual channel architecture described above in order to segregate or separate control of the brakes <NUM> and monitoring of the brake temperatures (via brake temperature sensors <NUM>) that communicated and send/receive data on different pathways. In various embodiments, due to the above-described segregated architecture, the first (primary) BCU <NUM>, when takeoff power is applied to the throttle, is configured to be in an active mode controlling braking, while the second (alternate) BCU <NUM> is configured to be in a different mode (i.e., non-active mode, such as a standby mode) to monitor brake temperatures. In various embodiments, during landing, brake control is alternated between the first (primary) BCU <NUM> and the second (alternate) BCU <NUM> in substantially the same manner as with the primary BCU <NUM> and alternate BCU <NUM> as discussed above. To facilitate this, during landing, the shuttle valve operation may be switched over (via the channel network <NUM> coupled to the alternate system) to put the second BCU <NUM> in an active mode to control brake operation via the channel network 432c, while placing the first BCU <NUM> in a standby mode. The channel network <NUM> are hydraulic lines and are not directly connected to the BCU <NUM>. Instead, the channel network <NUM> is in fluid communication with various valves, wherein the valves comprise actuators that are capable of being commanded from an open position, to a closed position and to positions therebetween by at least of BCU <NUM> and BCU <NUM>. The switching back and forth between the primary and alternate (secondary) control system prevents latent defects from occurring in either system, and a cycling back and forth process can be configured in landing between each control system.

<FIG> illustrates a flow diagram of the switching between the primary and alternate brake control units <NUM>, <NUM> in the landing mode of a flight in accordance with various embodiments. In <FIG>, in the flow diagram <NUM>, initially after actuation of the system, an evaluation is made at step <NUM> to determine if the aircraft is operating in a takeoff flight phase. This evaluation is made in order to configure the primary and alternate brake control units <NUM>, <NUM> for operation consistent with takeoff mode settings. If the evaluation determines that the aircraft is in take off mode, at step <NUM>, the primary system, i.e., the first (primary) BCU <NUM> is activated with functionality and channel configuration appropriate to perform a set of functions for configuration as the brake control system. At step <NUM>, the alternate brake control system, i.e., the second (alternate) BCU <NUM> is activated in a different mode (i.e., temperature monitoring mode) as the brake temperature monitoring system.

In various embodiments, at step <NUM>, if the determination is that the aircraft is not operating in the takeoff mode, the flow proceeds to step <NUM> and a determination is made as to whether the aircraft is in an approach or landing phase of flight operations. At step <NUM>, once determined that operation of the aircraft is in the approach or landing phase, a determination is made as to whether the active brake control unit in the previous landing cycle was the first (primary) BCU <NUM>. If it is determined that the active brake control system during the previous landing cycle was the first (primary) BCU <NUM>, then at step <NUM> the second (alternate) BCU <NUM> is activated as the brake control system for the landing, and the previously activated primary system (operative in the previous landing cycle) is placed in a different mode (i.e., standby mode).

At step <NUM>, if the determination is that the first (primary) BCU <NUM> was not active in the previous landing cycle, then at step <NUM> the first (primary) BCU <NUM> is activated as the brake control system for the approach (i.e., landing), and the second (alternate) BCU <NUM> is placed in a different mode (i.e., standby mode) and used only for brake temperature monitoring system. In this manner, both the primary and alternate braking control units alternate between performing brake functions in the approach phase to prevent a loss of function of a brake based on a single failure. This also enables the alternate brake control unit to perform the two functions of <NUM>) acting as a standby module to relieve the primary braking system if there is a failure and also <NUM>) providing the function of temperature monitoring of the brake operation without the need for a separate unit to perform temperature monitoring. Activating only one of the primary or alternate braking system as the active braking system prevents propagation of a failure mode between both the primary brake control unit and the alternate brake control unit, which could cause an un-commanded brake action to at least one wheel of the aircraft.

However, the benefits, advantages, solutions to problems, and any elements that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as critical, required, or essential features or elements of the invention. The scope of the invention is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean "one and only one" unless explicitly so stated, but rather "one or more.

Systems, methods, and apparatus are provided herein. After reading the description, it will be apparent to one skilled in the relevant art(s) how to implement the invention in alternative embodiments.

Numbers, percentages, or other values stated herein are intended to include that value, and also other values that are about or approximately equal to the stated value, as would be appreciated by one of ordinary skill in the art encompassed by various embodiments of the present invention. A stated value should therefore be interpreted broadly enough to encompass values that are at least close enough to the stated value to perform a desired function or achieve a desired result. The stated values include at least the variation to be expected in a suitable industrial process, and may include values that are within <NUM>%, within <NUM>%, within <NUM>%, within <NUM>%, or within <NUM>% of a stated value. Additionally, the terms "substantially," "about" or "approximately" as used herein represent an amount close to the stated amount that still performs a desired function or achieves a desired result. For example, the term "substantially," "about" or "approximately" may refer to an amount that is within <NUM>% of, within <NUM>% of, within <NUM>% of, within <NUM>% of, and within <NUM>% of a stated amount or value.

Furthermore, no element, component, or method step in the present invention is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims.

Claim 1:
A brake system, comprising:
a primary brake control unit; and
an alternate brake control unit;
characterised in that,
in response to the primary brake control unit being placed in an active mode, the primary brake control unit is configured to send data on a set of channels to control brake operation of at least one brake (<NUM>, <NUM>) , while the alternate brake control unit is configured to receive data to monitor brake temperature on another, separate set of channels coupled to at least one brake temperature sensor associated with the at least one brake (<NUM>, <NUM>).