Systems and methods for brake actuator operation sensor error compensation

The present disclosure provides systems and methods for brake actuator operation sensor error compensation. In various embodiments, a system for brake actuator operation sensor error compensation determines the existence of potential sensor errors and compensates for the effects of such errors.

FIELD

The present disclosure relates to aircraft braking systems, and more specifically, to systems and methods for sensor error detection for brake sensors.

BACKGROUND

An aircraft may comprise electro-mechanical brake actuators (EBA) that are configured to apply force to a brake stack on an aircraft wheel. A load cell may be coupled to the EBAs in order to provide feedback in regards to the amount of force that each EBA is applying to the brake stack. A high level command, such as brake control deflection from the cockpit, for example, may send a signal to an electro-mechanical brake actuator controller (EBAC), which in turn gets sent to the EBAs, which in turn each apply a force on the brake stack in order to decrease the radial velocity of the wheel. During an event where a sensor fails, the EBAC may over drive or underdrive one or more EBA.

SUMMARY

A method of brake actuator operation sensor error compensation is disclosed. The method may include polling, by an aircraft electro-mechanical brake actuator controller, a plurality of inputs including at least one of a plurality of load cell forces, a plurality of current sensor currents, and a plurality of position sensor positions, performing, by the controller, a conformance test in response to the polling, rejecting, by the controller, non-conforming inputs in response to the conformance test, and outputting, by the controller, a compensation signal to a command force controller. In various embodiments, the command force controller includes the aircraft electro-mechanical brake actuator controller.

In various embodiments, the conformance test includes performing a least squares fit of the plurality of inputs whereby non-conforming inputs are identified for rejection. In various embodiments, the conformance test further includes performing a Euclidean fit of the plurality of inputs whereby non-conforming inputs are identified for rejection. In various embodiments, the conformance test further includes performing a medial least squares fit of the plurality of inputs whereby non-conforming inputs are identified for rejection. In various embodiments, the conformance test further includes performing a planar fit of subsets of the plurality of inputs, wherein median calculations are performed of coefficients, whereby non-conforming inputs are identified for rejection.

In various embodiments, the plurality of inputs includes four inputs, and wherein the subsets include three of the four inputs. In various embodiments, the compensation signal includes an indication to increase or decrease a braking force. In various embodiments, the polling, by an aircraft electro-mechanical brake actuator controller, is performed by at least one of a measured current error detector, a measured position error detector, and a measured force error detector logically partitioned within the electro-mechanical brake actuator controller.

A tangible, non-transitory memory configured to communicate with a controller is also disclosed. The tangible, non-transitory memory may have instructions stored thereon that, in response to execution by the controller, cause the controller to perform operations including a method of brake actuator operation sensor error compensation.

A system for brake actuator operation sensor error compensation is also disclosed. The system may include at least one of a first load cell, a second load cell, a third load cell, and a fourth load cell each in communication with a command force controller and a measured force error detector, a first current sensor, a second sensor, a third current sensor, and a fourth current sensor each in communication with the command force controller and a measured current error detector, and a first position sensor, a second position sensor, and a third position sensor, each in communication with the command force controller and a measured position error detector. In various embodiments, an output compensation signal is output to the command force controller by the at least one of the measured current error detector, the measured position error detector, and the measured force error detector. In various embodiments, the command force controller commands an electric brake actuator to actuate an actuator motor whereby a pressure plate exerts a force on a disc in response to the output compensation signal. The forgoing features and elements may be combined in various combinations without exclusivity, unless expressly indicated herein otherwise. These features and elements as well as the operation of the disclosed embodiments will become more apparent in light of the following description and accompanying drawings.

DETAILED DESCRIPTION

The detailed description of exemplary embodiments herein makes reference to the accompanying drawings, which show exemplary embodiments by way of illustration. While these exemplary embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, it should be understood that other embodiments may be realized and that logical changes and adaptations in design and construction may be made in accordance with this disclosure and the teachings herein. Thus, the detailed description herein is presented for purposes of illustration only and not of limitation. The scope of the disclosure is defined by the appended claims. For example, the steps recited in any of the method or process descriptions may be executed in any order and are not necessarily limited to the order presented. Furthermore, any reference to singular includes plural embodiments, and any reference to more than one component or step may include a singular embodiment or step.

As used herein, “electronic communication” means communication of electronic signals with physical coupling (e.g., “electrical communication” or “electrically coupled”) or without physical coupling and via an electromagnetic field (e.g., “inductive communication” or “inductively coupled” or “inductive coupling”).

In various embodiments, systems with feedback control may become inoperable if a sensor which provides the feedback fails. The failure of a single sensor may cause an entire system to fail due to the dependence of other components on the failed sensor. Various systems and methods to address these challenges are presented herein. For instance, a system may be configured to receive data from a secondary operable sensor in the event that the primary sensor fails.

Various embodiments include an aircraft electro-mechanical brake actuator controller (EBAC). The EBAC may comprise a processor. The EBAC involves the transmission of power and data across a system of circuits and wires. According to instructions stored thereon, a tangible, non-transitory memory may be configured to communicate with the EBAC.

While described in the context of aircraft applications, and more specifically, in the context of brake control, the various embodiments of the present disclosure may be applied to any suitable application.

FIG. 1illustrates an aircraft brake100in accordance with various embodiments. Aircraft brake100may include a plurality of actuator motors102, a plurality of electromechanical brake actuators104, a plurality of ball nuts106, an end plate111and a pressure plate110, and a plurality of rotating discs112and stators114positioned in an alternating fashion between end plate111and pressure plate110. Rotating discs112may rotate about an axis115and the stators114may have no angular movement relative to axis115. Wheels may be coupled to rotating discs112such that a linear speed of the aircraft is proportional to the angular speed of rotating discs112. As force is applied to pressure plate110towards end plate111along the axis115, rotating discs112and stators114are forced together in an axial direction. This causes the rotational speed of rotating discs112to become reduced (i.e., causes braking effect) due to friction between rotating discs112, stators114, end plate111and pressure plate110. When sufficient force is exerted on rotating discs112via pressure plate110, the rotating discs112will stop rotating.

In order to exert this force onto pressure plate110, actuator motor102may cause electromechanical brake actuator104to actuate. In various embodiments, actuator motor102may be a brushless motor, such as a permanent magnet synchronous motor (PMSM), a permanent-magnet motor (PMM) or the like. In various embodiments, and with reference toFIG. 2, electromechanical brake actuator104may be coupled to or otherwise operate a motor shaft204and a pressure generating device, such as, for example, a ball screw, a ram, and/or the like. In response to actuation, electromechanical brake actuator104causes the motor shaft204to rotate. Rotation of the motor shaft204may cause rotation of a ball screw206, and rotational motion of the ball screw206may be transformed into linear motion of a ball nut106. With reference again toFIG. 1, linear translation of ball nut106towards pressure plate110applies force on pressure plate110towards end plate111.

Electromechanical brake actuator104is actuated in response to current being applied to actuator motor102. The amount of force applied by electromechanical brake actuator104is related to the amount of current applied to actuator motor102. With reference again toFIG. 2, in various embodiments, an electromechanical brake actuator control system200may comprise a current sensor212to detect an amount of current provided to actuator motor102. Current sensor212may be in communication with actuator motor102and/or with various other components of an electromechanical brake actuator104, an electromechanical brake actuator control system200, and/or an aircraft. In various embodiments, current sensor212may be disposed on or adjacent to actuator motor102. However, current sensor212may be disposed in any location suitable for detection of electrical current supplied to the actuator motor102.

Application of current to actuator motor102causes rotation of motor shaft204. In various embodiments, electromechanical brake actuator control system200may comprise a position sensor208. Position sensor208may be configured so as to measure the rotational speed and position of motor shaft204. In various embodiments, position sensor208may be disposed in or adjacent to electromechanical brake actuator104, or on or adjacent to actuator motor102. However, position sensor208may be disposed in any location suitable for detection of the rotational speed and position of motor shaft204. In various embodiments, position sensor208may comprise a resolver, tachometer, or the like.

In various embodiments, electromechanical brake actuator control system200may comprise a load cell202. Load cell202may be configured so as to measure the amount of force being applied between ball nut106and pressure plate110. In various embodiments, load cell202may be disposed in or adjacent to electromechanical brake actuator104, or on or adjacent to ball nut106. However, load cell202may be disposed in any location suitable for detection of the force being applied between ball nut106and pressure plate110. A controller may receive the detected force and rotational speed, and calculate an adjusted force and an adjusted rotational speed based on those detected values. In various embodiments, electromechanical brake actuator control system200may comprise a fault tolerant module210.

In various embodiments, a system for brake actuator operation with sensor fault tolerant technology comprises one or more load cell202, one or more position sensor208, one or more current sensor212and at least one controller. In various embodiments, fault tolerant module210may be a controller and/or processor. In various embodiments, fault tolerant module210may be implemented in a single controller and/or processor. In various embodiments, fault tolerant module210may be implemented in multiple controllers and/or processors. In various embodiments, fault tolerant module210may be implemented in an electromechanical actuator controller and/or a brake control unit.

System program instructions and/or controller instructions may be loaded onto a non-transitory, tangible computer-readable medium having instructions stored thereon that, in response to execution by a controller, cause the controller to perform various operations. The term “non-transitory” is to be understood to remove only propagating transitory signals per se from the claim scope and does not relinquish rights to all standard computer-readable media that are not only propagating transitory signals per se. Stated another way, the meaning of the term “non-transitory computer-readable medium” and “non-transitory computer-readable storage medium” should be construed to exclude only those types of transitory computer-readable media which were found in In Re Nuijten to fall outside the scope of patentable subject matter under 35 U.S.C. §101.

FIG. 3illustrates, in accordance with various embodiments, a system300for brake actuator operation with sensor fault tolerant technology (hereinafter “system300”). In various embodiments, system300may comprise a closed-loop system. In various embodiments, system300may be implemented in a machine-readable non-transitory medium and performed by a controller, for example, a fault tolerant module210(FIG. 2). In various embodiments, system300may be implemented on a special use controller, field programmable gate array, or the like. In various embodiments, system300may be implemented on one or more controllers. In various embodiments, system300may be implemented in a controller, for example a fault tolerant module210(FIG. 2) that comprises a logical unit of an electro-mechanical brake actuator controller (EBAC).

In various embodiments, system300may comprise sub-systems with like components denoted by like numerals with differing alphabetical characters, for example brake subsystems301A,301B,301C, and301D may be like subsystems containing further like subsystems such as EBAs104A,104B,104C, and104D.

In various embodiments, system300may receive a command force321from a command force controller320. Command force321may be sent via an electro-mechanical brake actuator controller (EBAC). Command force321may be the force which is being commanded to be applied to an electro-mechanical brake actuator (EBA) in order to apply a braking force to a vehicle such as an aircraft, for example. In various embodiments, command force controller320comprises a logical aspect of the EBAC.

The system300may monitor the behavior of the different EBAs in response to command force321by monitoring various sensors. For example, a current sensor105A may be associated with an EBA104A of a subsystem301A that may provide the current consumed by the actuator motor102of the subsystem301A. A position sensor208A may be associated with an EBA104A of a subsystem301A that may provide the position of the motor shaft204of the subsystem301A. A load cell202A may be associated with an EBA104A of a subsystem301A that may provide the force exerted between ball nut106and pressure plate110associated with an EBA104A of a subsystem301A.

Each current sensor105A,105B,105C,105D may provide current data to a measured current error detector401. Each position sensor208A,208B,208C,208D may provide position data to a measured position error detector403. Each load cell202A,202B,202C, and202D may provide force data to a measured force error detector405. Each of the measured force error detector405, the measured position error detector403, and current measured current error detector401may also receive the command force321. In this manner the detectors401,403, and405may perform methods disclosed further herein whereby sensor malfunctions may be detected and the effects of these malfunctions ameliorated.

For example, with reference toFIG. 4, a sensor malfunction amelioration method500is disclosed. A sensor malfunction amelioration method500may be implemented in one or more detector401,403, and/or405. In various embodiments one or more of detector401,403, and405may be omitted, for instance, a particular embodiment may have a one or more of a set comprising a measured force error detector405, a measured position error detector403, and/or a measured current error detector401, or may have two or more of such set, or may have all three such detectors.

A sensor malfunction amelioration method500may comprise polling inputs (step501). For instance the implementing detector401,403, and/or405may poll the inputs A, B, C, D, and ingest the sensor data present thereon. The sensor data thereon may comprise a value sampled upon one or more point in time (“polled”). Errors may exist in the sensor data, such as due to wear, malfunction, and sampling or quantization errors.

Subsequently a conformance test may be performed (step503). For instance, errors, such as those associated with input(s) indicative of a malfunctioning sensor may be determined. Simply averaging the inputs may prove unreliable, as an input having an error may deviate significantly more from the other inputs than the other inputs do from one another. Thus, a mechanism of rejecting inputs which are corrupted by such errors is implemented. In addition, perturbations in various inputs may arise for mechanical reasons. For instance, a brake rotor or stator may become asymmetrically shaped through wear over time and thus periodic perturbations may arise in different inputs over time as the inputs are periodically polled. Thus, the mechanism of rejecting inputs is desired to be adaptable, for instance, capable of implementation at every polling interval, and is further desired to be capable of differentiating between (1) errors which cause a value of an input to lie outside a planar fit with the other inputs (likely to be a malfunctioning sensor) and (2) errors which do not extract the value of the input from a planar fit with the other inputs (likely to be a mechanical wobble, precession, asymmetry, or other perturbation of an aspect of the braking system, for instance, a rotating mass component).

As such, different combinations of spatial curve fits are performed. For instance, a least squares fit of the four inputs may be formed. Least squares fitting is an approach in regression analysis that determines an approximate solution of an over determined system. Because there are more equations than unknown values in an over determined system, least squares fitting provides an overall solution that minimizes the sum of the squares of the errors made in the results of each equations. Stated differently, the best fit minimizes the sum of squared residuals (a difference between an observed value (e.g., input) and a fitted value provided by a model). As such, the solution is an approximate solution, and as such is subject to different approaches whereby the solution may be optimized. Different mechanisms of least squares fitting may be applied to the various inputs. For instance, in various embodiments, a Euclidean fit may be performed (which has some level of outlier rejection) and/or a medial least squares fit may be performed (which may have superior outlier rejection).

Moreover, and as briefly mentioned, planar fits of different combinations of three of the four inputs may be performed (for instance {A B C}, {A B D}, {B C D}, and {A C D}) and compared. In various embodiments, median calculations may be made of the coefficients. As such, inputs with values that lie outside a planar fit of other inputs may be rejected. These values and inputs are called “outlier values” and “non-conforming inputs” respectively, and may be rejected (step505).

Thus, perturbations in the input (such as a load on a load cell due to disc distortion) may be compensated for if desired and yet malfunctioning sensors may yet be determined despite such perturbations

Finally, a compensation signal is provided to the command force controller320whereby the command force321may be varied whether collectively or independently for each EBA104A,104B,104C, and104D, whereby brake performance may be enhanced (step507). For instance, the compensation signal may comprise an indication to increase or decrease a braking force.