Fault-tolerant brake load reduction

Abstract

To provide a fault-tolerant brake load alleviation system.SOLUTION: A brake system control unit includes one or more sensor interfaces configured to receive a brake torque signal from a brake torque sensor. The brake system control unit also includes a torque estimator configured to generate an estimated brake torque signal based, at least in part, on a brake model and a brake actuator command. The brake system control unit further includes control circuitry configured to generate the brake actuator command to actuate a brake actuator of a brake system. The brake actuator command is generated based on a brake pedal command and a load alleviation command. The load alleviation command is based on the brake torque signal or the estimated brake torque signal, depending on whether a sensor fault condition associated with the brake torque sensor is detected.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] TECHNICAL FIELD The present disclosure relates generally to brake load reduction systems and methods, and more particularly to fault-tolerant brake load reduction systems and methods. [Background technology]

[0002] Other factors being equal, lighter vehicles tend to be more efficient than heavier vehicles. Summary of the Invention [Problem to be solved by the invention]

[0003] Therefore, while vehicle designers, manufacturers, and users may prefer to reduce the structural weight of their vehicles, the options for reducing the weight of many vehicle structures are limited due to material and design considerations. For example, a vehicle undergoing heavy braking can experience significant loads. The magnitude of the expected loads due to heavy braking can be large enough to drive down the design of the structure for the vehicle, which can result in an increase in vehicle weight. [Means for solving the problem]

[0004] In certain implementations, the brake system control unit includes one or more sensor interfaces configured to receive a brake torque signal from a brake torque sensor. The brake system control unit also includes a torque estimator configured to generate an estimated brake torque signal based at least in part on a brake model and a brake actuator command. The brake system control unit further includes control circuitry configured to generate a brake actuator command to actuate a brake actuator of the brake system. The brake actuator command is generated based on a brake pedal command and a load shedding command. The load shedding command is based on the brake torque signal or the estimated brake torque signal depending on whether a sensor fault condition associated with the brake torque sensor is detected.

[0005] In another particular implementation, a method includes receiving a brake pedal command at a brake system control unit. The method also includes determining, at the brake system control unit, whether a sensor failure condition is detected based on a brake torque signal from a brake torque sensor. The method further includes, in response to detecting the sensor failure condition, accessing a brake model from a memory accessible to the brake system control unit, generating an estimated brake torque signal based on the brake model and the brake actuator command, and generating a load shedding command based on the estimated brake torque signal.

[0006] In another specific implementation, a vehicle includes one or more wheels coupled to a structure and one or more brake systems. Each brake system includes one or more sensors and one or more brake actuators. The vehicle also includes one or more brake system control units. Each brake system control unit includes one or more sensor interfaces configured to receive a brake torque signal from a brake torque sensor. Each brake system control unit also includes a torque estimator configured to generate an estimated brake torque signal based at least in part on a brake model and a brake actuator command. Each brake system control unit further includes control circuitry configured to generate a brake actuator command to actuate the brake actuator of the one or more brake actuators. The brake actuator command is generated based on a brake pedal command and a load shedding command. The load shedding command is based on the brake torque signal or the estimated brake torque signal depending on whether a sensor fault condition associated with the brake torque sensor is detected.

[0007] The features, functions, and advantages described herein may be realized separately in various implementations or may be combined in yet other implementations, further details of which can be found in the following description and by reference to the drawings. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram of a braking system configured to provide fault-tolerant brake load reduction, according to a particular implementation. [Figure 2] 2 is a block diagram of a vehicle including the braking system of FIG. 1 coupled to one or more structures, according to certain implementations. [Figure 3] 2 illustrates aspects of the brake system of FIG. 1 according to certain implementations. [Figure 4] 2 illustrates aspects of the brake system of FIG. 1 according to certain implementations. [Figure 5] FIG. 2 shows an example of a table containing historical brake command and brake torque data according to a particular implementation of the brake system of FIG. 1. [Figure 6] 1. FIG. 4 illustrates another example of a table containing historical brake command and brake torque data according to a particular implementation of the brake system of FIG. [Figure 7] FIG. 2 illustrates an example of a data structure containing historical brake command and brake torque data according to a particular implementation of the brake system of FIG. 1. [Figure 8] 2 is a graph illustrating aspects of a brake model according to a particular implementation of the brake system of FIG. 1; [Figure 9] 2 is a flowchart of a method performed by the brake system of FIG. 1 according to a particular implementation. [Figure 10] 10 is a flowchart of another method performed by the brake system of FIG. 1 according to certain implementations. [Figure 11] 2 is a flowchart showing the life cycle of a vehicle including the brake system control unit of FIG. 1. [Figure 12] 2 is a diagram illustrating a specific example of a vehicle including the brake system control unit of FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0009] The weight of structural elements coupled to the braking system of some vehicles can be reduced by using a brake load reduction system, which protects the structural elements of the vehicle by limiting the load on the structural elements during braking. For example, a closed-loop brake load reduction system uses sensor feedback data to indicate the braking force or torque to be applied during braking and limits the braking force or torque to a specified threshold to protect the structural elements of the vehicle.

[0010] The sensors that provide the sensor feedback data in such systems are typically located at or near the wheels of the vehicle. As such, these sensors may be exposed to harsh environments that may lead to sensor failure. When sensor feedback data is unavailable due to sensor failure, the brake load alleviation system is bypassed or operates in open-loop mode.

[0011] When the brake load alleviation system is bypassed or in open-loop mode, it is possible that the load limits imposed by the brake load alleviation system may be exceeded unless other operational limitations are imposed on the vehicle. For example, an aircraft may need to operate at a reduced takeoff weight limit to ensure that structural load limits are not exceeded. As another example, the braking distance of the vehicle may be increased to reduce peak braking forces. In the aircraft example, an increased braking distance may require the aircraft to use a longer runway, which may delay the aircraft's deployment if such a runway is unavailable or overburdened.

[0012] Aspects disclosed herein present systems and methods for fault-tolerant brake load alleviation. The disclosed systems and methods enable improved operation of brake load alleviation systems in the presence of sensor failures. For example, the disclosed systems and methods can enable operation of brake load alleviation systems even in the presence of a sensor failure that prevents a conventional brake load alleviation system from performing its desired function. The disclosed fault-tolerant brake load alleviation systems and methods use a vehicle-specific (or axle- or wheel-specific) brake model generated during closed-loop operation to generate an estimated feedback sensor signal when a feedback signal is unavailable or unreliable (e.g., due to a sensor failure). Because the brake model is custom-built for a particular vehicle (and possibly a vehicle-specific axle or wheel) and frequently updated, the estimated feedback signal reliably limits the loads experienced by the vehicle structure and enables vehicle operation without imposing additional operational limitations (e.g., operating weight limitations or braking distance limitations).

[0013] The figures and the following description illustrate certain exemplary embodiments. Those skilled in the art will understand that, although not explicitly described or shown herein, they can devise various configurations that embody the principles described herein and are included within the scope of the claims that follow this description. Furthermore, any examples described herein should be construed as aiding in understanding the principles of the disclosure and not as limiting. Consequently, the disclosure is not limited to the specific embodiments or examples described below, but rather by the claims and their equivalents.

[0014] Certain implementations are described herein with reference to the drawings. In the description, common features are designated by common reference numerals throughout the drawings. Some features described herein are singular in some implementations and plural in other implementations. For example, FIG. 2 depicts a vehicle 200 including one or more brake systems 100 (“brake system(s)” in FIG. 2 ), indicating that in some implementations, the vehicle 200 includes a single brake system 100 and in other implementations, the vehicle 200 includes multiple brake systems 100. For ease of reference herein, such features are generally introduced as “one or more” features, and then optionally referred to in the plural, which is indicated by “(s)” following the term, such as “brake system(s)” 100 in FIG. 2 . Such features may also be referred to in the singular when representatives of such features are described.

[0015] Various terms used herein are used only for the purpose of describing particular embodiments and are not intended to be limiting. For example, the singular forms "a," "an," and "the" include the plural unless the context clearly dictates otherwise. The terms "comprise," "comprises," and "comprising" are used interchangeably with "include," "includes," or "including." Additionally, the term "wherein" is used interchangeably with the term "where." As used herein, "exemplary" denotes examples, implementations, and / or aspects and should not be construed as limiting or as indicating a preferred or preferred implementation. As used herein, ordinal terms (e.g., "first," "second," "third," etc.) used to modify elements such as structures, components, acts, etc., do not in themselves imply any preference or order of an element relative to another element, but rather (when ordinal terms are used) merely distinguish an element from other elements with the same name. As used herein, the term "set" refers to a grouping of one or more elements, and the term "plurality" refers to a plurality of elements.

[0016] As used herein, "generating," "calculating," "using," "selecting," "accessing," and "determining" have the same meaning unless the context indicates otherwise. For example, "generating," "calculating," or "determining" a parameter (or signal) can refer to actively generating, calculating, or determining a parameter (or signal), or can refer to using, selecting, or accessing a parameter (or signal) that has already been generated by another component, device, or the like. "Coupled," as used herein, can include "communicatively coupled," "electrically coupled," or "physically coupled," and also (or alternatively) can include any combination thereof. Two devices (or components) can be directly or indirectly coupled (e.g., communicatively coupled, electrically coupled, or physically coupled) via one or more other devices, components, wires, buses, networks (e.g., wired networks, wireless networks, or combinations thereof), etc. Two electrically coupled devices (or components) can be included in the same device or in different devices and can be connected via electronics, one or more connectors, or inductive coupling, as illustrative, non-limiting examples. In some implementations, two devices (or components) that are communicatively coupled, such as via electrical communication, can send and receive electrical signals (digital or analog signals) directly or indirectly via one or more wires, buses, networks, etc. As used herein, "directly coupled" is used to describe two devices that are coupled (e.g., communicatively coupled, electrically coupled, or physically coupled) without any intervening components.

[0017] The following description will often refer to brake torque as an indicator of the load applied to the vehicle's structure. First, it should be noted that brake force or brake load may be used instead of or in addition to brake torque to indicate the load applied to the vehicle's structure. For ease of explanation (e.g., rather than always referring to "brake torque or brake force"), brake torque will be used throughout the following description. However, throughout the following description, it will be understood that brake force can be substituted for brake torque, with corresponding calculations modified as necessary (e.g., converting force to torque by using data describing the brake system configuration and attachment to the structure).

[0018] FIG. 1 depicts an example of a brake system 100 according to a particular implementation. The brake system 100 includes a brake load reduction system 134 configured to limit the load on a vehicle structure during vehicle braking. The target brake load of the brake load reduction system 134 may vary over time to further limit dynamic braking loads. As a result, the structure can be designed to withstand lower braking loads than would be encountered in the absence of the brake load reduction system 134. The brake load reduction system 134 limits the braking load using feedback from one or more brake torque sensors 126 (e.g., a brake torque signal 128). For example, the brake torque signal 128 indicates the load on the vehicle structure during a braking operation, and during normal operation (e.g., when no sensor failure is detected), the brake load reduction system 134 determines a load reduction command 136 based on the brake torque signal 128. The load reduction command 136 is used to limit the brake actuator command 118 sent to the brake actuation system 120 in response to the brake pedal command 106.

[0019] Brake system 100 further includes a fault-tolerant torque system 130. Fault-tolerant torque system 130 is configured to detect whether brake torque sensor 126 is experiencing a fault condition. If fault-tolerant torque system 130 detects a fault condition associated with brake torque sensor 126, fault-tolerant torque system 130 provides an estimated brake torque signal 132 (instead of brake torque signal 128) to brake load alleviation system 134. Estimated brake torque signal 132 is generated based on a model of brake system 100. In certain aspects, during a braking operation in which fault-tolerant torque system 130 does not detect a fault condition, fault-tolerant torque system 130 updates the model of brake system 100. As a result, the model is periodically updated, and fault-tolerant torque system 130 can generate a value for estimated brake torque signal 132 that most closely approximates the value of brake torque signal 128 that would exist if the sensor fault condition did not exist.

[0020] Braking system 100 includes a pedal system 104 configured to generate a brake pedal command 106 based on input from a user 102. Brake pedal command 106 is combined at a first node 108 with a load shedding command 136 to generate a brake load shedding compensation brake pedal command 110. Load shedding command 136 limits brake pedal command 106 to prevent braking operations from exceeding specified load limits associated with the structure.

[0021] In some implementations, the brake system 100 includes or is coupled to a brake automation system 112 that provides a brake command (e.g., a brake automation system command 114) at a second node 116 that is combined with the brake load reduction compensation brake pedal command 110 to generate a brake actuator command 118. In implementations that do not include the brake automation system 112, the brake load reduction compensation brake pedal command 110 is used as the brake actuator command 118.

[0022] Brake actuator command 118 is provided to brake actuation system 120, which actuates brakes 124 in response to brake actuator command 118. Brake 124 performs a braking action that reduces the vehicle's speed and applies the resulting load to the vehicle's structure. If brake torque sensor 126 is operating properly, brake torque sensor 126 sends brake torque signal 128 to fault-tolerant torque system 130. Brake torque signal 128 is indicative of the measured brake torque generated due to the braking action. If brake torque sensor 126 experiences a fault condition, brake torque sensor 126 does not generate brake torque signal 128 or generates brake torque signal 128 outside of an expected range.

[0023] A fault tolerant torque system 130 evaluates the brake torque signal 128 to determine if the brake torque sensor 126 is experiencing a fault condition. If a fault condition is not detected, the fault tolerant torque system 130 outputs the brake torque signal 128 to a brake load reduction system 134. If a fault condition is detected, the fault tolerant torque system 130 outputs an estimated brake torque signal 132. The estimated brake torque signal 132 is generated based on a model of the brake system 100 and the brake actuator commands 118, as described further below.

[0024] The brake load reduction system 134 generates a load reduction command 136 based on the brake torque signal 128 or the estimated brake torque signal 132. Thus, the brake load reduction system 134 can reliably operate when a sensor failure condition is detected.

[0025] FIG. 2 depicts an example of a vehicle 200 including one or more wheels 204 coupled to one or more structures 202. The vehicle 200 also includes one or more braking systems 100. The braking systems 100 are configured to limit the load on the structure 202 during braking. As a result, the structure 202 can be designed to withstand lower braking loads than might be encountered without the described braking system 100. Ensuring that the structure 202 experiences lower braking loads allows vehicle designers to reduce the overall weight of the vehicle 200. The vehicle 200 can include or correspond to any wheeled vehicle with onboard brakes. For example, the vehicle 200 can be a land vehicle such as a truck, train, or automobile. As another example, the vehicle 200 can be an aircraft, in which case the wheels 204 correspond to wheels mounted on the landing gear. Additionally, the vehicle 200 can be powered by an onboard engine or motor, or the vehicle 200 can be powered by an off-board source. For example, the vehicle 200 may include a trailer or train with an on-board braking system.

[0026] In certain implementations, each wheel 204 is associated with a brake system 100. In some implementations, one brake system 100 is associated with two or more of the wheels 204 (e.g., multiple wheels on a common axle). In the example shown in FIG. 2 , each brake system 100 includes a brake actuation system 120, such as a pneumatic, electric, or hydraulic power source, that provides power to operate one or more brake actuators 236 of the brake system 100. In other implementations, two or more brake systems 100 share a brake actuation system 120. For example, a single hydraulic system may be coupled to two or more brake systems 100 of the vehicle 200.

[0027] Many implementations use friction-based braking. In such implementations, each brake actuator 236 is indirectly coupled to one of the wheels 204 via a pair of friction surfaces. For example, the wheel 204 is coupled to a rotor or drum including a first friction surface that rotates with the wheel 204. In this example, the brake actuator 236 associated with the wheel 204 is coupled to a brake stator, brake pad, or brake shoe including a second friction surface. The brake actuator 236 moves the second friction surface into or out of contact with the first friction surface. For example, during braking, the brake actuator 236 presses the second friction surface into contact with the first friction surface, slowing the rotational speed of the wheel 204. In other implementations, the brake system 100 uses another mechanism in addition to or instead of friction to slow the rotational speed of the wheel 204. One example of a non-friction-based braking mechanism is regenerative braking, in which electromotive force is used to slow the rotational speed of the wheel 204. Other examples include compression braking or hydraulic braking, in which braking causes compression of a fluid or induces a drag force in a fluid to slow the rotational speed of the wheels 204 .

[0028] 2 , the braking system 100 includes or is associated with a brake automation system 112, such as an automatic braking system 212 and / or an anti-skid system 214. The braking system 100 also includes one or more brake system control units 220. Each brake system control unit 220 includes a control circuit 222, one or more sensor interfaces 224, and a brake load reduction system 134. In some implementations, the brake automation system 112 is integrated within the brake system control unit 220. In yet other implementations, the brake automation system 112 is omitted.

[0029] The sensor interface 224 of the brake system control unit 220 is configured to receive sensor data and / or signals from sensors 230 of the brake system 100. For example, the sensors 230 may include one or more brake torque sensors 126 configured to provide one or more brake torque signals to the brake system control unit 220 via the sensor interface 224. In some implementations, one or more brake load sensors may be used instead of or in addition to the brake torque sensors 126. As another example, the sensors 230 may include one or more brake operating environment sensors 234 configured to provide one or more brake operating environment signals to the brake system control unit 220 via the sensor interface 224. The brake operating environment sensors 234 measure conditions such as vehicle speed, ground speed, wheel speed, brake temperature, wheel temperature, or other braking-related conditions.

[0030] Control circuit 222 is configured to generate brake actuator commands to actuate brake actuators 236 in response to one or more brake input signals (e.g., brake pedal command 106 in FIG. 1 , brake automation system command 114 in FIG. 1 , or both). Brake load alleviation system 134 is configured to provide load alleviation commands 136 in FIG. 1 to control circuit 222 to limit the brake actuation signals such that such load on a portion of structure 202 during braking is below a specified load limit 254.

[0031] For example, during operation, the brake system 100 receives a brake input signal (e.g., the brake pedal command 106 of FIG. 1 , the brake automation system command 114 of FIG. 1 , or both). The brake system control unit 220 provides the brake actuator command 118 of FIG. 1 to the brake actuation system 120 based on the brake input signal and based on a load shedding command 136 from the brake load shedding system 134. During normal operation, the load shedding command 136 is based on the brake torque signal 128 from the brake torque sensor 126. However, when the sensor monitor 240 of the fault tolerant torque system 130 detects a sensor fault condition associated with the brake torque sensor 126, the load shedding command 136 from the brake load shedding system 134 is determined based on one or more brake models 256 of the fault tolerant torque system 130.

[0032] The sensor monitor 240 is configured to detect a fault condition associated with the sensor 230. For example, the sensor monitor 240 may compare the measured brake torque value (indicated by the brake torque signal 128 in FIG. 1 ) to one or more fault criteria 242. In this example, the fault criteria 242 indicate an expected range of brake torque values, and the sensor monitor 240 indicates that a sensor fault condition has been detected if the measured brake torque value is outside the expected range of brake torque values. In some implementations, the expected range of brake torque values ​​is based on brake torque values ​​stored in memory during operation of the brake system 100 when no fault condition was detected. Additionally or alternatively, in some implementations, the expected range of brake torque values ​​is based on default values, such as brake torque values ​​determined during testing of the vehicle 200 or other similar vehicles.

[0033] In some implementations, at least one of the fault criteria 242 is based on a historical brake torque value and one or more brake actuator command values ​​associated with the one or more historical brake torque values. The brake actuator command values ​​correspond to values ​​indicated by the brake actuator commands 118 in FIG. 1 . For example, the brake actuator commands 118 may indicate a relative magnitude of a braking action, such as a percentage of the operating range of the brake system 100. For example, a brake actuator command value of fifty percent (50%) indicates that the braking action should be approximately half as aggressive as the braking action performed in response to a brake actuator command value of one hundred percent (100%). FIG. 5 illustrates an example of a table 500 illustrating thresholds 508 associated with the fault criteria 242 according to a particular implementation. In FIG. 5 , the table 500 includes a set of initial default brake torque values ​​504 and a set of subsequent historical brake torque values ​​506, each corresponding to a particular value of the brake actuator command. In some implementations, the table 500 represents values ​​of particular braking environmental conditions, such as a particular brake temperature, wheel temperature, wheel speed, ground speed, or a combination thereof, that may affect the brake torque. In such implementations, other tables may be used to represent values ​​for other braking environmental conditions.

[0034] 5, threshold value 508 indicates a lower limit of valid brake torque sensor readings for each brake actuator command value. For example, for a ten percent (10%) brake actuator command value 502, a brake torque sensor reading of 0 ft-lb (foot-pounds) or greater is considered valid based on threshold value 508, while for a fifty percent (50%) brake actuator command value 502, a brake torque sensor reading of 24,200 ft-lb or greater is considered valid. In some implementations, table 500 may also indicate an upper threshold value for one or more brake actuator command values ​​502.

[0035] In some implementations, the threshold value 508 is determined based on the historical brake torque values ​​506. For example, the threshold value 508 for a fifty percent (50%) brake actuator command value may be determined based on a statistical analysis of the historical brake torque values ​​506 corresponding to the fifty percent (50%) brake actuator command values. For example, the threshold value 508 for a fifty percent (50%) brake actuator command value may be set based on a multiple (e.g., 2X) of the standard deviation of the historical brake torque values ​​506 corresponding to the fifty percent (50%) brake actuator command values. In other illustrative examples, other statistical analyses may be used to determine a lower (or upper) limit for valid sensor readings based on the historical brake torque values ​​506.

[0036] Returning to the example of Figure 2, the fault-tolerant torque system 130 includes a torque estimator 250 configured to generate the estimated brake torque signal 132 of Figure 1 when the sensor monitor 240 detects a sensor fault condition. The estimated brake torque signal 132 is based, at least in part, on one or more brake models 256 and brake actuator commands 118 provided to the brake actuation system 120. The brake model 256 relates the brake actuator commands 118 (and possibly other data, such as braking operating environment data) to historical brake torque values ​​measured during periods of operation where no sensor fault was detected. As an example, the brake model 256 may include parameters of a gain-based torque estimation function, such as Equation 1: τ estimate =B×G Equation 1 where τ estimate is an estimated brake torque value, B is a value indicating the magnitude of the braking action (e.g., the value of the brake actuator command), and G is a brake gain value based on historical brake torque measurements during a period when no sensor faults were detected. In some implementations, the brake gain value G has different values ​​depending on brake operating environment values ​​such as wheel speed, ground speed, brake temperature, or wheel temperature.

[0037] Additionally or alternatively, the value of the brake gain value G may be valid for a particular range of brake actuator command values. For example, the matrix data structure may include brake gain values ​​G for various combinations of brake actuator command values, wheel speeds, ground speeds, brake temperatures, wheel temperatures, or other braking-related values. In some situations, the estimated brake torque value τ estimate The brake gain value G used to calculate the estimated brake torque value τ may be determined by interpolation between available brake actuator command values ​​and brake gain values. estimate is determined by selecting a brake gain value G based on the brake actuator command value B, the value of the brake operating environment signal, or both, and multiplying the selected brake gain value G by the brake actuator command value B.

[0038] As another example, brake model 256 may include one or more tables or other data structures or knowledge representations that store measured brake torque values ​​when particular brake actuator commands 118 were provided to brake actuation system 120 during past braking operations when no sensor failure was detected. In this example, if a sensor failure is detected during braking, the value of brake actuator command 118 sent to brake actuation system 120 is used to look up, retrieve, and / or calculate an estimated brake torque value from brake model 256. If the value of brake actuator command 118 does not exactly correspond to the brake actuator command value in brake model 256, the estimated brake torque value may be estimated by interpolation between two or more values ​​in brake model 256. Alternatively, brake model 256 may include both brake gain value G from Equation 1 and values ​​from one or more tables. In this example, a rough estimate of the brake torque value may be determined from one or more tables and subsequently refined using the brake gain function.

[0039] FIG. 6 illustrates an example of a table 600 showing estimated brake torque values ​​602 for various brake actuator command values ​​502 according to a particular implementation. In FIG. 6, the table 600 includes a set of initial default brake torque values ​​504 and a set of historical brake torque values ​​506, as described with reference to FIG. 5. In the example illustrated in FIG. 6, the estimated brake torque value 602 associated with each brake actuator command value 502 is an average of the historical brake torque values ​​506 for the brake actuator command value 502. For example, for a brake actuator command value 502 of thirty percent (30%), the estimated brake torque value 602 is 30756, which is an average determined based on the historical brake torque values ​​506. In some implementations, a moving average value is used. For example, after a certain number of historical brake torque values ​​506 are stored in table 600, each new historical brake torque value 506 added to table 600 replaces the oldest historical brake torque value 506 for the same brake actuator command value 502, and the average of the historical brake torque values ​​506 is recalculated to determine the estimated brake torque value 602 for the brake actuator command value 502. If sufficient historical brake torque values ​​506 are not available, an initial default brake torque value 504 is used to determine the estimated brake torque value 602.

[0040] In some implementations, the brake load alleviation system 134 includes different brake models 256 for different braking environments. In such implementations, the particular brake model 256 to be used in a particular situation is selected based on braking environment values ​​from the brake environment sensor 234. For example, FIG. 7 shows an example of a set of tables 700 for brake models 256 according to a particular implementation. In the example of FIG. 7, table 600 is a first table associated with a first braking environment value, such as a first brake temperature value T1. In this example, the set of tables 700 also includes one or more additional tables associated with other braking environment values, such as a second table 704 associated with a second brake temperature value T2 and a third table 706 associated with a third brake temperature value T3. In this example, the estimated brake torque value may be interpolated between tables 600, 704, 706, between brake actuator command values ​​502, or both. For example, the estimated brake torque value for a forty-five percent (45%) brake actuator command value 502 at brake temperature values ​​between T2 and T1 may be determined by interpolation between the estimated brake torque values ​​associated with forty percent (40%) and fifty percent (50%) brake actuator command values ​​502 for brake temperature T1 and the estimated brake torque values ​​associated with forty percent (40%) and fifty percent (50%) brake actuator command values ​​502 for brake temperature T2. Although brake temperature is used as an example in Figure 7, other examples use other brake operating environment values ​​in addition to or instead of brake temperature.

[0041] 8 illustrates an example of a brake model 256 represented as a surface 812 in a configuration space 802 according to another particular implementation. In FIG. 8, the configuration space 802 has a brake actuator command dimension 806, a brake torque dimension 808, and one or more brake operating environment dimensions 804. For ease of explanation, only one brake operating environment dimension 804 is shown in FIG. 8, but in some implementations, the configuration space 802 includes two or more brake operating environment dimensions 804. For example, the configuration space 802 may include a wheel temperature dimension and a wheel speed dimension or some other combination of brake operating environment dimensions.

[0042] In the example shown in Figure 8, the coordinate location within configuration space 802 of a particular point on surface 812 indicates an expected brake torque value for given braking environment values ​​and brake actuator command values. For example, in Figure 8, point 810 on surface 812 can be identified based on a braking environment coordinate (e.g., approximately E3 in Figure 8) and a brake actuator command value coordinate (e.g., approximately 75% in Figure 8). The braking environment coordinate and the brake actuator command coordinate together specify a unique location on surface 812, and the estimated brake torque value for the unique location (e.g., point 810) is specified by the brake torque coordinate of point 810.

[0043] 2 , fault-tolerant torque system 130 also includes a model updater 252. Model updater 252 is configured to update brake model 256 when a sensor fault condition associated with brake torque sensor 126 is not detected. For example, model updater 252 may store model update data relating values ​​from brake actuator command 118 to brake torque values ​​from brake torque signal 128. As another example, model updater 252 may verify or update parameters of a brake gain function (such as Equation 1) based on the value of brake actuator command 118 and the brake torque value. In some implementations, the model update data also relates values ​​of braking operating environment data to brake actuator command values ​​and the brake torque signal.

[0044] Thus, the fault-tolerant torque system 130 enables fault-tolerant and reliable operation of the brake load alleviation system 134 when a sensor failure condition is detected. For example, on an aircraft, the fault-tolerant torque system 130 determines the force or torque gain for each brake on a given landing gear and stores the information in memory of the brake system control unit 220 to generate a brake model 256. The brake model 256 is regularly or periodically updated (by the model updater 252) to account for changes in the brake system 100 or other parts of the vehicle 200. During an initial learning phase (e.g., before sufficient actual operating data is available to generate a brake model 256 customized for the brake system 100), the brake model 256 uses default values ​​(e.g., based on vehicle testing or certification data or conservative engineering estimates). For example, during the initial learning phase, the fault-tolerant torque system 130 determines the estimated brake torque signal 132 using the initial parameters of the brake model 256 and then uses the updated parameters generated by the model updater 252.

[0045] 2 as separate components, in other implementations, the described functions of two or more of the sensor interface 224, the control circuit 222, the fault tolerant torque system 130, and the brake load reduction system 134 may be performed by a single component. In some implementations, each of the sensor interface 224, the control circuit 222, the fault tolerant torque system 130, and the brake load reduction system 134 may correspond to or include hardware such as an application specific integrated circuit (ASIC) or a field programmable gate array (FPGA), or the operations described with reference to the sensor interface 224, the control circuit 222, the fault tolerant torque system 130, and the brake load reduction system 134 may be performed by a processor executing computer-readable instructions.

[0046] Figure 3 is a diagram illustrating aspects of the brake system 100 of Figures 1 and 2 according to a particular implementation. The diagram shown in Figure 3 illustrates a single wheel 204 and associated components (e.g., one or more struts 312, a brake actuator 236, an actuator sensor 238, a brake clamp 314, one or more rotors 316, one or more brake torque sensors 126, and one or more brake operating environment sensors 234). When more than one wheel 204 of a vehicle 200 has brakes, the control circuit 222, brake load alleviation system 134, fault tolerant torque system 130, and components associated with the wheel 204 may be replicated for each wheel being braked.

[0047] 3, a brake pedal 332 is coupled to a brake pedal sensor 302. The brake pedal sensor 302 generates a brake pedal input signal 304 based on the position of the brake pedal 332. A brake pedal command logic 306 generates a brake pedal command 106 that is provided to the control circuit 222 and the fault-tolerant torque system 130. In the implementation shown in FIG. 3, the fault-tolerant torque system 130 uses the brake pedal command 106 to determine a braking mode that assists in detecting sensor failures, as described with reference to FIG. 4.

[0048] A first node 108 of the control circuit 222 determines a brake load shedding compensating brake pedal command 110 based on the difference between the brake pedal command 106 and a brake load shedding command 136 from a brake load shedding system 134. The brake load shedding command 136 is based on either the brake torque signal 128 or the estimated brake torque signal 132 from the fault tolerant torque system 130.

[0049] In the example of Figure 3, the second node 116 determines the brake actuator command 118 based on the brake load reduction compensation brake pedal command 110 and one or more brake automation system commands 114 from the brake automation system 112. In this example, the brake automation system 112 includes a system or component that provides brake input via a mechanism other than the brake pedal 332. The automatic braking system 212 and the anti-skid system 214 of Figure 2 are examples of such a brake automation system 112. Although Figure 3 illustrates the first node 108 and the second node 116 as summing nodes, more complex control logic may be used in other implementations.

[0050] In the example of Figure 3, brake actuator command 118 is provided to fault-tolerant torque system 130. Brake actuator command 118 is also provided to brake actuation system 120 of Figures 1 and 2, which in Figure 3 includes a third node 308, brake actuator 236, actuator sensor 238, and compensator 322. Third node 308 generates brake actuator signal 310 based on brake actuator command 118 and actuator compensation command 324 from compensator 322. Compensator 322 generates actuator compensation command 324 based on actuator sensor signal 320 from actuator sensor 238 associated with brake actuator 236. For example, in Figure 3, compensator 322 may compensate for servo or valve response characteristics of brake actuator 236. In another example, compensator 322 may be coupled to multiple brake actuators 236 and actuator sensors 238. In this example, the compensator 322 may be used to adjust the brake actuator signals 310 sent to the multiple brake actuators 236 based on the brake actuator commands 118 to equalize braking among the multiple brake actuators 236.

[0051] 3 , in response to the brake actuator signal 310, the brake actuator 236 causes the brake clamp 314 to contact or press against the rotor 316, thereby braking the wheel 204 and applying torque to the structure 202 via a braking force coupled to the structure 202 via the strut 312. The brake torque sensor 126 is coupled to the strut 312, the structure 202, or both, and generates a brake torque signal 128 indicative of the braking torque applied to the structure 202. In some implementations, the dimensions of the strut 312 are known, and the braking torque may be indicated by measuring the braking force applied by the brake clamp 314. In such implementations, a force sensor rather than a torque sensor may be used to measure a value indicative of the braking torque.

[0052] The brake torque signal 128 is provided to the fault-tolerant torque system 130. Additionally, in some implementations, the brake operating environment sensor 234 provides one or more brake operating environment signals 330 as inputs to the fault-tolerant torque system 130. The fault-tolerant torque system 130 evaluates the brake torque signal 128 (e.g., based on the fault criteria 242 of FIG. 2 ) to determine whether a sensor failure condition is detected. If a sensor failure condition is not detected, the fault-tolerant torque system 130 provides the brake torque signal 128 to the brake load alleviation system 134. In this situation, the brake load alleviation system 134 generates a load alleviation command 136 based on the brake torque signal 128. In some implementations, when a sensor failure is not detected, the fault-tolerant torque system 130 also generates model update data to update the brake model 256 using the brake torque signal 128, the brake actuator command 118, and the brake operating environment signals 330.

[0053] If the fault tolerant torque system 130 detects a sensor failure, the fault tolerant torque system 130 provides an estimated brake torque signal 132 to a brake load shedding system 134. In this situation, the brake load shedding system 134 generates a load shedding command 136 based on the estimated brake torque signal 132. The fault tolerant torque system 130 calculates or looks up an estimated brake torque value under similar braking operating conditions (indicated by the braking operating environment signal 330) based on historical values ​​of brake torque in response to similar values ​​of the brake actuator command 118. Further details regarding the operation of the fault tolerant torque system 130 are described below.

[0054] Figure 4 illustrates aspects of the brake system 100 of Figures 1-3 according to a particular implementation. In particular, Figure 4 illustrates further details of the fault-tolerant torque system 130 and the interaction between the fault-tolerant torque system 130 and other components of the vehicle 200 of Figure 2.

[0055] In FIG. 4 , brake pedal sensor 302 sends brake pedal input signal 304 to brake pedal command logic 306. Brake pedal command logic 306 generates a filtered position signal 404 by passing brake pedal input signal 304 through anti-aliasing filter 402. Brake pedal command logic 306 applies pedal gain 406 to filtered position signal 404 to generate brake pedal command 106. Brake pedal command 106 is provided to control circuit 222, which generates brake actuator command 118 based in part on brake pedal command 106. In some implementations, such as the example shown in FIG. 3 , brake pedal command 106 is also provided to fault-tolerant torque system 130. For example, in such implementations, brake pedal command 106 may be provided to braking mode detector 424 to facilitate detection of a sensor failure condition, as described further below. In other implementations, such as the example shown in FIG. 4 , brake actuator command 118 is used for braking mode detection.

[0056] 4, brake actuator command 118 is sent to brake actuation system 120. Brake actuation system 120 generates a braking force (and corresponding braking torque) resulting from braking in response to brake actuator command 118. Brake gain 410 describes the relationship between the value of brake actuator command 118 and the value of the braking force or braking torque.

[0057] The brake torque sensor 126 generates a brake torque signal 128 indicative of the brake torque. The brake torque signal 128 is provided to the fault tolerant torque system 130. Additionally, in some implementations, the brake operating environment sensor 234 provides the brake operating environment signal 330 to the fault tolerant torque system 130. In the example shown in FIG. 4 , the brake operating environment sensor 234 includes one or more of a brake temperature sensor 412, a wheel temperature sensor 414, a wheel speed sensor 416, and a ground speed sensor 418.

[0058] 4, the fault tolerant torque system 130 uses a low pass filter 420 to remove high frequency components from the brake torque signal 128 to generate a filtered torque signal 422. The filtered torque signal 422, the brake operating environment signal 330, and the brake actuator command 118 (or brake pedal command 106) are provided as inputs to the sensor monitor 240.

[0059] In FIG. 4 , the sensor monitor 240 includes a braking mode detector 424. The braking mode detector 424 determines whether a braking maneuver should be evaluated by the fault-tolerant torque system 130. Because the function of the brake load alleviation system 134 is to limit the load on certain structures of the vehicle during braking, factors that contribute to the loading of certain structures are considered to determine whether a braking operation should be evaluated by the fault-tolerant torque system 130. For example, the braking mode detector 424 may consider braking operation environment information, such as wheel speed or ground speed, determined from the braking operation environment signal 330. In this example, if the wheel speed or ground speed is below a threshold, the braking mode detector 424 may determine that the fault-tolerant torque system 130 does not need to evaluate a braking operation, in which case no further action is taken by the fault-tolerant torque system 130. As another example, the braking mode detector 424 may consider the magnitude of the braking operation, as indicated by the brake pedal command 106 or the brake actuator command 118. In this example, if the magnitude of the braking operation is below a threshold, the braking mode detector 424 can determine that the fault-tolerant torque system 130 does not need to evaluate the braking operation, in which case no further action is taken by the fault-tolerant torque system 130.

[0060] If the braking mode detector 424 determines that a braking action should be evaluated by the fault-tolerant torque system 130, the sensor monitor 240 compares the brake torque signal 128, the filtered torque signal 422, or both, to the fault criteria 242. In the example of FIG. 4, if no fault is detected, valid sensor data 426 is provided to the model updater 252, and the brake torque signal 128 is provided to the brake load shedding system 134 for generating the load shedding command 136. Alternatively, in the example of FIG. 4, if a fault is detected, the fault indication signal 434 is provided to the torque estimator 250, which determines the estimated brake torque signal 132 based on the model output 442. The estimated brake torque signal 132 is provided to the brake load shedding system 134 for generating the load shedding command 136.

[0061] The valid sensor data 426 includes data from the brake torque signal 128 and the brake actuator command 118. In some implementations, the valid sensor data 426 also includes data from the brake operating environment signal 330. The model updater 252 uses the valid sensor data 426 to generate model update data 432 and update the brake model 256. As an example, the model updater 252 stores historical data 428 indicative of historical values ​​of the valid sensor data 426, such as historical valid brake torque signal values, corresponding brake actuator command values, and corresponding brake temperature values. The model updater 252 adds the valid sensor data 426 as one or more data entries in the historical data 428, and a calculator 430 of the model updater 252 determines the model update data 432 based on the valid sensor data 426 and the historical data 428. For example, as described with reference to FIG. 6 , the calculator 430 may determine an average or running average of the historical data 428. 8 to generate model update data 432. As yet another example, calculator 430 may shift or modify surface 812 in configuration space 802 of FIG. 8 to generate model update data 432. As yet another example, calculator 430 may update brake gain parameters used by a torque estimation function, such as Equation 1 above. In some implementations, historical data 428, including valid sensor data 426, may be used to update or modify thresholds 508 used by fault criteria 242, as described with reference to FIG. 5. Model update data 432 is stored in memory 436 for updating one or more tables 438 of brake model 256, for updating one or more parameters 440 of brake model 256, or both.

[0062] The fault indication signal 434 causes the torque estimator 250 to generate the estimated brake torque signal 132 based on a model output 442 that is based on the brake actuator command 118 and the brake model 256. In some implementations, the torque estimator 250 generates the estimated brake torque signal 132 further based on the brake operating environment signal 330. As a first example, when the brake model 256 includes a table 438 or other data structure (such as those shown in FIGS. 5-7) that stores estimated brake torque values ​​for particular brake actuator command values, the torque estimator 250 looks up the value of the estimated brake torque signal 132 from the table 438 or other data structure based on the value of the brake actuator command 118. As a second example, when the brake model 256 includes parameters 440 of a function (such as the brake gain parameter in Equation 1), the torque estimator 250 calculates the value of the estimated brake torque signal 132 based on the value of the brake actuator command 118 and the brake gain parameter value.

[0063] 9 is a flowchart of an example method 900 implemented by the brake system 100 of Figures 1-4, according to a particular implementation. For example, the method 900 may be initiated, performed, or controlled by the fault tolerant torque system 130 or one or more components thereof.

[0064] The method 900 includes receiving at least a brake actuator command at block 902. For example, the fault-tolerant torque system 130 of FIGS. 1-4 receives the brake actuator command 118 from the control circuit 222. At block 902, the method 900 may also include receiving other signals, including a brake torque signal and / or one or more brake operating environment signals. For example, the fault-tolerant torque system 130 of FIGS. 1-4 receives the brake torque signal 128 from the brake torque sensor 126 and the brake operating environment signal 330 from the brake operating environment sensor 234. In some circumstances, the brake torque sensor 126 may experience a fault condition that results in the fault-tolerant torque system 130 not receiving the brake torque signal 128 when the brake torque signal 128 is expected (e.g., during a braking operation in which significant brake torque is generated). Such a situation results in the detection of a fault condition, as described further below.

[0065] Method 900 includes performing braking mode detection at block 904, which in method 900 includes determining whether the brakes are applied at block 906. For example, the determination of whether the brakes are applied may be made based on brake pedal command 106 or based on brake actuator command 118. If the determination at block 906 is that the brakes are not applied, method 900 returns to block 902 to await receipt of the next signal.

[0066] If the determination at block 906 is that the brakes are applied, the method 900 proceeds to determine whether the speed of the vehicle 200 is greater than a threshold at block 908. For example, a wheel speed value or a ground speed value from the braking environment signal 330 may be compared to a threshold. If the determination at block 908 is that the speed of the vehicle 200 is less than (or equal to or less than) the threshold, the method 900 returns to block 902 and waits to receive the next signal. If the determination at block 908 is that the speed of the vehicle 200 is greater than the threshold, the method 900 determines at 910 whether a fault condition has been detected. In implementations that do not use the braking environment sensor 234 to generate the braking environment signal 330, the determination at block 908 is omitted.

[0067] If the brake torque signal 128 is received at block 902, determining whether a fault condition is detected at block 910 includes comparing the value indicated by the brake torque signal 128 to the fault criteria 242 to determine whether the brake torque signal value is valid. If the value indicated by the brake torque signal 128 is valid (e.g., if the value of the brake torque signal is within the threshold range indicated by the fault criteria 242), block 910 indicates that a fault has not been detected, and the method 900 proceeds to block 912. If the value indicated by the brake torque signal 128 is not valid (e.g., if the value of the brake torque signal 128 is outside the threshold range indicated by the fault criteria 242), block 910 indicates that a fault has been detected, and the method 900 proceeds to block 914. Further, in some implementations, if the brake torque signal 128 is not received in block 902 when it is expected (e.g., when the brake mode detection of block 904 indicates that the brakes are applied and the vehicle is traveling at a speed greater than a threshold), block 910 indicates that a fault has been detected.

[0068] If the determination at block 910 is that a fault condition is not detected, the brake torque signal 128 is deemed to include valid sensor data 426, and the method 900 includes, at block 912, updating the brake model based on the valid sensor data 426. For example, the valid sensor data 426 may be provided to a model updater 252, which may update the brake model 256.

[0069] If the determination at block 910 is that a fault condition is detected, the method 900 includes, at block 914, generating the estimated brake torque signal 132 based on the brake model 256. For example, the torque estimator 250 may use the brake model 256 and the brake actuator command 118 to determine the value of the estimated brake torque signal 132.

[0070] Additionally, if the determination in block 910 is that a fault condition is not detected, the value indicated by the brake torque signal 128 is provided to the brake load reduction system 134. Alternatively, if the determination in block 910 is that a fault condition is detected, the estimated brake torque signal 132 is provided to the brake load reduction system 134.

[0071] 10 is a flowchart of another example of a method 1000 implemented by the brake system 100 of FIGS. 1-4, according to a particular implementation. For example, the method 1000 may be initiated, performed, or controlled by the fault-tolerant torque system 130 or a component thereof.

[0072] At block 1002, the method 1000 includes determining whether a sensor fault condition is detected based on the brake torque signal 128 from the brake torque sensor 126. For example, the sensor monitor 240 of the fault tolerant torque system 130 determines whether a sensor fault condition is detected based on the brake torque signal 128 from the brake torque sensor 126. In some implementations, the fault tolerant torque system 130 also uses other data, such as the value of the brake pedal command 106, the value of the brake actuator command 118, the value of the brake operating environment signal 330, or a combination thereof, to determine whether a sensor fault condition is detected.

[0073] If a determination is made at block 1004 that a sensor fault condition has not been detected, then the method 1000 includes generating a brake actuation signal based on the brake torque signal at block 1012. For example, as shown in FIG. 3 , the fault-tolerant torque system 130 provides the brake torque signal 128 to the brake load alleviation system 134 when a sensor fault condition does not exist, and the brake load alleviation system 134 generates its alleviation command 136 based on the brake torque signal 128. In this example, the control circuit 222 generates the brake actuator command 118 using the alleviation command 136 and the brake pedal command 106. Thus, in this situation, the brake actuator command 118 is based on the brake torque signal 128.

[0074] Upon determining at block 1004 that a sensor failure condition has been detected, the method 1000 includes accessing a brake model from memory accessible to the brake system control unit at block 1006. For example, the brake system control unit 220 of FIG. 2 accesses the brake model 256. In some implementations, such as those shown in FIGS. 5-7, the brake model 256 includes a plurality of data entries representing historical brake torque values ​​506 corresponding to various brake actuator command values ​​502. In some such implementations, the plurality of data entries also includes one or more default brake torque values ​​504, each representing a brake torque to be used for a respective brake command value until a sufficient number of historical brake torque values ​​506 have been accumulated. In other implementations, the brake model 256 includes parameters 440 of a brake gain function, such as Equation 1, where the values ​​of the parameters 440 of the brake gain function are based on the historical brake torque values ​​and the corresponding brake command values. In some such implementations, the initial or default parameter values ​​of the parameters 440 may be used until the parameters 440 are updated to generate updated parameter values ​​based on the model update data 432 .

[0075] The method 1000 also includes, at block 1008, generating the estimated brake torque signal 132 based on the brake model 256 and the brake actuator commands 118. For example, the torque estimator 250 generates the estimated brake torque signal 132 based on the brake model 256 and based on the brake actuator commands 118. The brake actuator commands 118 are generated to limit the load on the structure 202 of the vehicle 200 due to braking to below a specified load limit. In some implementations, the estimated brake torque values ​​of the estimated brake torque signal 132 are determined by interpolation between brake torque values ​​from the brake model 256.

[0076] The method 1000 also includes, at block 1010, generating a load shedding command 136 based on the estimated brake torque signal 132. For example, as shown in Figures 1-4, the brake load shedding system 134 generates the load shedding command 136 based on the estimated brake torque signal 132 when a sensor failure condition is detected.

[0077] Method 1000 thus allows the brake load alleviation system to continue operating when the sensor is present. The disclosed fault-tolerant brake load alleviation system and method generates an estimated brake torque signal 132 when the brake torque signal 128 is unavailable or unreliable (e.g., due to a sensor failure) using a vehicle-specific brake model that was generated and / or updated in the absence of a sensor failure. Because the brake model is custom-built for a particular vehicle, the estimated brake torque signal 132 reliably limits the loads experienced by the vehicle structure, allowing the vehicle to operate without imposing further operational limitations (e.g., operating weight limitations or braking distance limitations).

[0078] Figure 11 is a flow chart illustrating a method 1100 representing the life cycle of a vehicle including the structure 202, sensor 230, and brake system control unit 220 of Figure 2. The vehicle may include an aircraft or a land vessel.

[0079] During preparation for manufacturing, example method 1100 includes, at block 1102, specification and design of a vehicle, such as vehicle 200 of Figure 2 or aircraft 1200 of Figure 12. During specification and design of the vehicle, method 1100 may include specification and design of structure 202, sensors 230, and brake system control unit 220. At block 1104, method 1100 includes material procurement, which may include procuring materials for structure 202, sensors 230, and brake system control unit 220.

[0080] During production, method 1100 includes component and subassembly manufacturing at block 1106 and system integration of the vehicle at block 1108. For example, method 1100 may include component and subassembly manufacturing and system integration of structure 202, sensors 230, and braking system control unit 220. At block 1110, method 1100 includes certification and delivery of the vehicle and, at block 1112, placing the vehicle in service. Certification and delivery may include certification of structure 202, sensors 230, and braking system control unit 220 to place them in service. While in service with a customer, the vehicle may be scheduled for routine maintenance and inspection (which may include modifications, reconfigurations, refurbishments, etc.). At block 1114 , the method 1100 includes performing maintenance and service on the vehicle, which may include performing maintenance and service on the structure 202 , the sensors 230 , and the brake system control unit 220 .

[0081] Each of the processes of method 1100 may be performed or carried out by a system integrator, a third party, and / or an entity (e.g., a customer). For purposes of this description, a system integrator may include, but is not limited to, any number of manufacturers and subcontractors of major systems; a third party may include, but is not limited to, any number of vendors, subcontractors, and suppliers; an entity may be an airline, a leasing company, a military entity, a service organization, etc.

[0082] Aspects of the present disclosure may be described in the context of an example vehicle, a particular example of which is an aircraft 1200 as shown in FIG.

[0083] In the example of Figure 12, aircraft 1200 includes an airframe 1250 that includes structure 202. Aircraft 1200 also includes a number of systems 1220 and an interior 1252. Examples of systems 1220 include one or more of propulsion system 1222, electrical system 1224, environmental system 1226, hydraulic system 1228, and braking system 100. Braking system 100 includes sensors 230 and braking system control unit 220 of Figure 2. Aircraft 1200 may also include any number of other systems.

[0084] In some implementations, a non-transitory computer-readable storage medium stores instructions that, when executed by one or more processors, cause the one or more processors to initiate, perform, or control operations that perform some or all of the functions described above. For example, the instructions may be executable to perform one or more of the operations or methods of Figures 1 through 10. In some implementations, some or all of one or more of the operations or methods of Figures 1 through 10 may be performed by one or more processors (e.g., one or more central processing units (CPUs), one or more graphics processing units (GPUs), one or more digital signal processors (DSPs)) executing instructions, by dedicated hardware circuitry, or any combination thereof.

[0085] The descriptions of the examples set forth herein are intended to provide a general understanding of the structure of various implementations. The figures do not serve as a complete description of all of the elements and aspects of apparatus and systems that utilize the structures or methods described herein. Many other implementations will be apparent to those skilled in the art upon reviewing this disclosure. Other implementations may be utilized and derived from the present disclosure, resulting in structural and logical substitutions and changes that may be made without departing from the scope of the present disclosure. For example, method actions may be performed in a different order than shown in the figures, and one or more method actions may be omitted. Accordingly, the present disclosure and figures should be considered illustrative and not limiting.

[0086] Furthermore, while specific examples have been shown and described herein, it should be understood that any subsequent configurations designed to achieve the same or similar results may be substituted for the specific implementations shown. The present disclosure encompasses any and all subsequent adaptations or variations of the various embodiments. Combinations of the above implementations with other implementations not specifically described herein will be apparent to those skilled in the art upon reviewing this description.

[0087] The Abstract of the Disclosure is presented with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. Additionally, in the foregoing Detailed Description, various aspects may be grouped together or described within a single implementation for the purpose of streamlining the disclosure. The above-described examples illustrate, but do not limit, the disclosure. It should also be understood that many modifications and variations are possible in accordance with the principles of the disclosure. As the following claims reflect, claimed subject matter may be directed to less than all aspects of any of the disclosed examples. Accordingly, the scope of the disclosure is defined by the following claims and their equivalents. [Explanation of symbols]

[0088] 100 Brake system, 102 User, 104 Pedal system, 106 Brake pedal command, 108 First node, 110 Brake load reduction compensation brake pedal command, 112 Brake automation system, 114 Brake automation system command, 116 Second node, 118 Brake actuator command, 120 Brake application system, 124 Brake, 126 Brake torque sensor, 128 Brake torque signal, 130 Fault-tolerant torque system, 132 Estimated brake torque signal, 134 Brake load reduction system, 136 Load reduction command, 200 Vehicle, 202 Structure, 204 Wheel, 212 Automatic braking system, 214 Anti-skid system, 220 Brake system control unit, 222 Control circuit, 224 Sensor interface, 230 Sensor, 234 Brake operating environment sensor, 236 Brake actuator, 238 Actuator sensor, 240 Sensor monitor, 242 Fault criteria, 250 Torque estimator, 252 Model updater, 254 Load limits, 256 Brake model, 302 Brake pedal sensor, 304 Brake pedal input signal, 306 Brake pedal command logic, 308 Third node, 310 Brake actuator signal, 312 Strut, 314 Brake clamp, 316 Rotor, 320 Actuator sensor signal, 322 Compensator, 324 Actuator compensation command, 330 Brake operating environment signal, 332 Brake pedal, 402 Anti-aliasing filter, 404 Filtered position signal, 406 Pedal gain, 410 Brake gain, 412 Brake temperature sensor, 414 Wheel temperature sensor, 416 Wheel speed sensor, 418 Ground speed sensor, 420 Low pass filter, 422 Filtered torque signal, 424 Brake mode detector, 426 Valid sensor data, 428 Historical data, 430 Calculator, 432 Model update data, 434 Fault indication signal, 436 Memory, 438 Table, 440 Parameters, 442 Model output, 500 Table, 502 Brake actuator command value, 504 Initial default brake torque value, 506 Historical brake torque value, 508 Threshold, 600 Table, 602estimated brake torque values, 700 set of tables, 704 tables, 706 tables, 802 configuration space, 804 brake operating environment dimensions, 806 brake actuator command dimensions, 808 brake torque dimensions, 810 points, 812 surfaces, 900 methods, 1000 methods, 1100 methods, 1200 aircraft, 1220 systems, 1222 propulsion systems, 1224 electrical systems, 1226 environmental systems, 1228 hydraulic systems, 1250 airframe, 1252 interior

Claims

1. one or more sensor interfaces (224) for receiving a brake torque signal (128) from a brake torque sensor (126); a torque estimator (250) that generates an estimated brake torque signal (132) based at least in part on a brake model (256) and the brake actuator command (118); a control circuit (222) that generates a brake actuator command to operate a brake actuator (236) of the braking system (100), the brake actuator command being generated based on a brake pedal command (106) and a load reduction command (136), the load reduction command being based on the brake torque signal or the estimated brake torque signal depending on whether a sensor fault condition associated with the brake torque sensor is detected; A brake system control unit (220) comprising:

2. 2. The brake system control unit of claim 1, further comprising a model updater configured to update the brake model by storing model update data relating brake actuator command values ​​from the brake actuator command to brake torque values ​​from the brake torque signal when a sensor fault condition associated with the brake torque sensor is not detected.

3. 3. The brake system control unit of claim 2, wherein the one or more sensor interfaces are further configured to receive sensor data from one or more brake operating environment sensors (234), and the model update data further relates the brake actuator command value and the brake torque value to brake operating environment values ​​from the sensor data.

4. The brake system control unit of claim 3 , wherein the one or more brake operating environment sensors measure one or more of ground speed, wheel speed, wheel temperature, and brake temperature.

5. 5. The brake system control unit of claim 1, wherein the brake model includes one or more tables (438), each table including a plurality of brake torque values ​​(602) and a corresponding plurality of brake actuator command values, and the estimated brake torque signal is determined, at least in part, by looking up a particular brake torque value in one or more of the tables based on a brake actuator command value from the brake actuator command.

6. 6. The brake system control unit of claim 1, further comprising a sensor monitor configured to detect the sensor fault condition based on a comparison of a measured brake torque value of the brake torque signal to one or more fault criteria.

7. 7. The brake system control unit of claim 6, wherein at least one of the one or more fault criteria is based on one or more historical brake torque values ​​(506) and one or more brake actuator command values ​​associated with the one or more historical brake torque values.

8. 8. The brake system control unit of claim 1, wherein the control circuit is further configured to generate the brake actuator commands such that a load on a structure of an aircraft due to braking is less than a specified load limit.

9. 9. The brake system control unit of claim 1, wherein the brake model includes one or more data tables, each of the one or more data tables including a running average of historical brake torque values ​​for each of a plurality of brake actuator command values.

10. The brake system control unit of any one of claims 1 to 9, wherein the brake model includes brake gain function parameters (440), the parameters being based on one or more historical brake torque values.

11. 11. A brake system control unit according to claim 1, wherein the torque estimator is configured to use default parameter values ​​of the brake model to generate the estimated brake torque signal during a first time period and to use updated parameter values ​​of the brake model to generate the estimated brake torque signal during a second time period subsequent to the first time period, the default parameter values ​​being based on test data and the updated parameter values ​​being based on sensor data values ​​from the brake system.

12. A brake system control unit according to any preceding claim, wherein the brake model is configured to provide an estimated brake torque value based on the brake actuator command value and brake operating environment values.

13. determining (1002) in the brake system control unit whether a sensor failure condition is detected based on a brake torque signal (128) from a brake torque sensor (126); in response to detecting the sensor fault condition; accessing (1006) a brake model (256) from a memory (436) accessible to said brake system control unit; generating (1008) an estimated brake torque signal (132) based on the brake model and brake actuator commands (118); generating (1010) a load reduction command (136) based on the estimated brake torque signal; A method (1000) comprising:

14. The method of claim 13, further comprising the step of generating the load reduction command based on the brake torque signal in response to a sensor failure condition not being detected (1012).

15. The method of claim 13 or 14, wherein the brake model includes a plurality of data entries representing historical brake torque values ​​(506) corresponding to various brake actuator command values ​​(502).

16. 16. The method of claim 15, wherein the plurality of data entries further includes one or more default data entries (504), each of the one or more default data entries representing a default brake torque value corresponding to a respective brake actuator command value.

17. 17. The method of claim 13, wherein the brake model includes brake gain function parameters (440), values ​​of the parameters of the brake gain function being based on historical brake torque values ​​and corresponding brake actuator command values.

18. 18. The method of any one of claims 13 to 17, wherein the estimated brake torque value of the estimated brake torque signal is determined by interpolation between historical brake torque values ​​from the brake model.

19. 19. The method of any one of claims 13 to 18, further comprising determining a brake pedal command based on a brake pedal sensor (302).

20. 20. The method of any one of claims 13 to 19, wherein the brake actuator commands are generated to limit loads on a structure (202) of an aircraft (1200) due to braking to below a specified load limit (254).

21. one or more wheels (204) coupled to the structure (202); one or more braking systems (100), each of which comprises one or more sensors (230) and one or more brake actuators (236); one or more brake system control units (220); Equipped with Each of the brake system control units is one or more sensor interfaces (224) for receiving a brake torque signal (128) from a brake torque sensor (126); a torque estimator (250) that generates an estimated brake torque signal (132) based at least in part on a brake model (256) and the brake actuator command (118); a control circuit (222) for generating a brake actuator command to actuate a brake actuator of one or more of the brake actuators, the brake actuator command being generated based on a brake pedal command (106) and a load relief command (136), the load relief command being based on the brake torque signal or the estimated brake torque signal; A vehicle (200) comprising:

22. 22. The vehicle of claim 21, further comprising at least one of an automatic braking system (212) and an anti-skid system (214) coupled to one or more of the brake system control units, and wherein the brake actuator commands are based at least in part on a signal (114) from at least one of the automatic braking system and the anti-skid system.

23. 23. A vehicle as claimed in claim 21 or 22, wherein one or more of the brake system control units comprises a brake load reduction system (134) that generates the load reduction command to limit a load on a portion of the structure due to braking to below a specified load limit (254).

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