Abstract:
An electronic actuator control system and method (“system”) are provided. The system may comprise an electro-mechanical actuator (EMA) configured to generate a force and an electro-mechanical actuator controller (EMAC) electrically coupled to the EMA. The EMAC may include a non-transitory memory communicating with the EMAC, the non-transitory memory having instructions stored thereon that, in response to execution by the EMAC, cause a processor to perform operations. The operations carried out by the EMAC may comprise commanding the EMA to apply a force, determining an expected voltage in response to the force, measuring a voltage generated by the EMA, and comparing the voltage generated by the EMA to the expected voltage.

Description:
FIELD OF INVENTION 
     The present disclosure relates to electronic brake systems, and, more specifically, to a method of detecting decreased efficiency in electric actuators. 
     BACKGROUND 
     Most mechanical components wear with time. An electro-mechanical actuator (EMA) is no different. Over time, the efficiency of an EMA may degrade due to internal wear and other factors. Reduced efficiency may result in slower response times and higher power consumption. Ultimately, an EMA may even fail as a result of wear. In an aircraft application, for example, EMA failure may have undesired side effects such as brake failure. Reduced efficiency in an EMA may be a precursor to complete failure. 
     SUMMARY 
     An electronic actuator control system and method (“system”) are provided. The system may comprise an electro-mechanical actuator (EMA) configured to generate a force and an electro-mechanical actuator controller (EMAC) electrically coupled to the EMA. The EMAC may include a non-transitory memory communicating with the EMAC, the non-transitory memory having instructions stored thereon that, in response to execution by the EMAC, cause a processor to perform operations. The operations carried out by the EMAC may comprise commanding the EMA to apply a force, determining an expected voltage in response to the force, measuring a voltage generated by the EMA, and comparing the voltage generated by the EMA to the expected voltage. 
     In various embodiments, the system may further comprise cutting power to the EMA after commanding the EMA to apply the force. The voltage may be generated by the EMA in response to the EMAC cutting power to the EMA. Determining the expected voltage may include looking up the force in a lookup table. The lookup table may associate the force with the expected voltage. The lookup table may also associate the force with a minimum voltage threshold. The system may further include generating a repair signal in response to the voltage being less than the minimum voltage threshold. The minimum voltage threshold may be 50% of the expected voltage. 
     The foregoing features and elements may be combined in various combinations without exclusivity, unless expressly indicated otherwise. These features and elements as well as the operation thereof will become more apparent in light of the following description and the accompanying drawings. It should be understood, however, the following description and drawings are intended to be exemplary in nature and non-limiting. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The subject matter of the present disclosure is particularly pointed out and distinctly claimed in the concluding portion of the specification. A more complete understanding of the present disclosure, however, may best be obtained by referring to the detailed description and claims when considered in connection with the figures, wherein like numerals denote like elements. 
         FIG. 1  illustrates an exemplary system for detecting potential EMA failure, in accordance with various embodiments; 
         FIG. 2  illustrates a flowchart of an exemplary method for detecting EMA failure and/or reduced efficiency, in accordance with various embodiments; and 
         FIG. 3  is a flow chart depicting logical steps taken by an EMAC to detect EMA failure, in accordance with various embodiments. 
     
    
    
     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 exemplary embodiments of 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 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. Also, any reference to attached, fixed, connected or the like may include permanent, removable, temporary, partial, full and/or any other possible attachment option. Additionally, any reference to without contact (or similar phrases) may also include reduced contact or minimal contact. Surface shading lines may be used throughout the figures to denote different parts but not necessarily to denote the same or different materials. 
     With reference to  FIG. 1 , an exemplary actuator control system  80  may have an electro-mechanical actuation controller  81  (“EMAC”), an electro-mechanical actuator (EMA)  83 , and an actuated component  85 . The EMAC  81  may provide force commands to the EMA  83  directing the EMA  83  to cause actuated component  85  to mechanically operate (e.g., moving aircraft brakes). For example, the EMAC  81  may be responsible for executing brake actuation instructions received via a logical connection, such as a controller area network (“CAN”) bus  87 , from other aircraft systems, such as a control unit  89  (e.g., a full authority digital controller or a brake control unit). In this manner, the actuator may be operated. In further embodiments, the EMAC  81  may provide force commands to more than one EMA  83 , for example, a first EMA and a second EMA, or any number of EMAs, in order to operate more than one component (e.g., a first brake assembly and a second brake assembly in concert). 
     As discussed herein, various aspects of the present disclosure may be implemented in various logical units of a processor having a non-transitory memory. In various embodiments, various aspects may be implemented in multiple processors and/or memories. For example, the disclosed system may be implemented within the EMAC  81 . Alternatively, various aspects of the disclosed system may be implemented within the EMAC  81  and/or the EMA  83  and/or control unit  89 . 
     With reference to  FIG. 2 , an exemplary method  200  of detecting EMA failure based on reduced efficiency is shown. Actuator control system  80  of  FIG. 1  may be configured to carry out the steps of method  200 . For example, EMAC  81  from  FIG. 1  may carry out the steps of method  200 . EMAC  81  may execute method  200  each time an aircraft is started. EMAC  81  may also execute method  200  multiple times to ensure the test results are accurate. 
     In various embodiments, EMAC  81  may command EMA  83  to apply a force (Step  202 ). The force may be of a predetermined amount. For example, EMA  83  may be a brake actuator commanded to apply a predetermined force so that the regenerative voltage produced when the brake releases may be predicted. EMAC  81  may then cut power to EMA  83  or otherwise command EMA  83  to release (Step  204 ). Continuing the above example, the brake actuator may release and be pushed back by the brake assembly. 
     In various embodiments, as an electric motor or actuator is rotated it may generate electricity. A brake actuator may spin in reverse after applying a force, a voltage may thus be generated by the brake actuator. Large regen voltages may damage circuits that direct EMA  83  to apply force. Thus, EMAC  81  may contain a circuit (referred to as a regen circuit) to detect and dissipate this voltage (i.e. by dissipating a voltage detected over a threshold across a resistor bank). EMAC  81  may measure this voltage generated by EMA  83 , which may be referred to as a regen voltage, by a circuit in the EMAC (Step  206 ). Continuing the above example, the regen voltage generated by the brake actuator spinning in reverse may be measured by the regen circuit of EMAC  81 . 
     In various embodiments, EMAC  81  may determine a threshold voltage (Step  208 ). The expected regen voltage in a given application may be predictable based on the force applied. Thus, when EMA  83  is operating at reduced efficiency as a result of wear, the regen voltage produced by EMA  83  may be lower than the expected regen voltage. In that regard, the expected regen voltage from EMA  83  based on the applied force may be used by EMAC  81  to determine the threshold voltage at which EMA failure is likely. 
     In various embodiments, EMAC  81  may look up the expected regen voltage in a lookup table. The expected regen voltage may be used by EMAC  81  to calculate the threshold voltage. For example, the lookup table may include a percentage of maximum force applied by EMA  83 , an expected regen voltage, and/or a minimum regen voltage threshold (See table T1, below). EMAC  81  may command the EMA  83  to apply 50% of the EMA&#39;s maximum rated force of 10,000 lbs, which would be 5,000 lbs, for example. EMAC  81  may determine the threshold voltage by looking up the expected voltage in the lookup table and calculate a percentage (e.g., 50%) of the expected voltage that corresponds to the threshold voltage. EMAC may also determine the threshold voltage by looking up a predetermined threshold voltage in the lookup table based on the force applied by EMA  83 . 
     
       
         
               
             
               
               
               
             
               
               
               
             
           
               
                 TABLE T1 
               
             
             
               
                   
               
               
                 Exemplary lookup table for associating a 
               
               
                 threshold voltage with an applied force. 
               
             
          
           
               
                 Force (% of Max) 
                 Expected Voltage (V) 
                 Threshold Voltage (V) 
               
               
                   
               
             
          
           
               
                 10 
                 30 
                 15 
               
               
                 25 
                 50 
                 25 
               
               
                 50 
                 150 
                 75 
               
               
                 75 
                 250 
                 125 
               
               
                 100 
                 500 
                 250 
               
               
                   
               
             
          
         
       
     
     In various embodiments, EMAC  81  may then compare the measured regen voltage to the threshold voltage (Step  210 ). The comparison may be done by comparing the measured regen voltage to a threshold voltage that is a percentage of the expected regen voltage, wherein a measured regen voltage below the threshold voltage may indicate EMA  83  is operating at low efficiency. Any percentage may be selected and programmed into EMAC  81  to indicate a desired efficiency threshold. Continuing the above example, the expected voltage generated by EMA  83  when applying 50% of maximum force (5,000 lbs in this example) may be 150 volts. EMAC  81  may measure a voltage of 70 volts being generated by EMA  83 . The minimum threshold voltage when applying 50% force is 75 volts according to the lookup table T1. 70 volts is less than the minimum threshold voltage of 75 volts, therefore EMA  83  is not generating the minimum threshold voltage. 
     In various embodiments, EMAC  81  may respond to EMA  83  failing to generate the minimum threshold voltage in various ways. For example, EMAC  81  may comprise a counter to count the number of failed checks. EMAC  81  may increment the counter each time EMA  83  fails to generate the expected regen voltage. Once the counter exceeds a predetermined number, a repair signal may be generated. The repair signal may be sent to ground crews to indicate the actuator should be replaced. 
     With reference to  FIG. 3 , a logical chart  300  depicting steps taken by EMAC  81  is shown, in accordance with various embodiments. EMAC  81  may measure a regen voltage produced by EMA  81  (Step  302 ). EMAC  81  may then determine the threshold value, as described with reference to  FIG. 2  above (Step  304 ). EMAC  81  may then check whether the measured regen voltage is below the threshold value (Step  306 ). If the measured regen voltage is below the threshold value then EMAC  81  may increment a counter (step  308 ). The counter may be used to track the number of failed tests by EMA  83 . In that regard, a single bad test may not result in a false failure signal. If the regen voltage is above the threshold, then the test is complete and EMA  83  has passed. EMAC  81  may check whether the counter is at a level indicating a signal should be generated (Step  310 ). If the counter is at the signal level then EMAC may generate a repair signal (Step  312 ). If the counter is below the signal level then the test is complete with the failed test indicated by the incremented counter. 
     In various embodiments, the repair signal may be used to indicate to ground crews or flight crews that preventative maintenance may be appropriate. The repair signal may result in a warning displayed on a handheld device or terminal to inform ground crews. The repair signal may also be displayed in avionics in the cockpit. In various embodiments, an inefficient actuator may still operate, albeit with greater power consumption than a new actuator. In that regard, maintenance may be delayed until the aircraft is at a convenient location to change the actuator. By detecting reduced EMA efficiency, actuator control system  80  may enable preventative maintenance. Inefficient actuators may be replaced prior to complete failure. As a result, power consumption of EMA  83  over the life of the aircraft may be reduced. 
     Benefits and other advantages have been described herein with regard to specific embodiments. Furthermore, the connecting lines shown in the various figures contained herein are intended to represent exemplary functional relationships and/or physical couplings between the various elements. It should be noted that many alternative or additional functional relationships or physical connections may be present in a practical system. However, the benefits, advantages, and any elements that may cause any benefit or advantage to occur or become more pronounced are not to be construed as critical, required, or essential features or elements of the disclosure. The scope of the disclosure is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.” Moreover, where a phrase similar to “at least one of A, B, or C” is used in the claims, it is intended that the phrase be interpreted to mean that A alone may be present in an embodiment, B alone may be present in an embodiment, C alone may be present in an embodiment, or that any combination of the elements A, B and C may be present in a single embodiment; for example, A and B, A and C, B and C, or A and B and C. 
     Systems, methods and apparatus are provided herein. In the detailed description herein, references to “various embodiments”, “one embodiment”, “an embodiment”, “an example embodiment”, etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described. After reading the description, it will be apparent to one skilled in the relevant art(s) how to implement the disclosure in alternative embodiments. 
     Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. No claim element herein is to be construed under the provisions of 35 U.S.C. 112(f), unless the element is expressly recited using the phrase “means for.” As used herein, the terms “comprises”, “comprising”, or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.