Abstract:
Embodiments are directed to obtaining data associated with at least one aircraft flight parameter when an aircraft is being operated in flight; processing the data to determine that the at least one aircraft flight parameter indicates a change in value in an amount greater than a threshold; and decoupling a load from the aircraft based on determining that the at least one aircraft flight parameter indicates the change in value in the amount greater than the threshold.

Description:
BACKGROUND 
     An aircraft, such as a rotorcraft, may be used to transport cargo or a payload to a destination. Slung load cargo may often contain sensitive equipment or may be subject to a maximum drop rate or impact force at the time of drop off. The cargo, or equipment contained therein, might not withstand excessive impact associated with gravitational forces. In autonomous cargo applications, such as in unmanned aerial vehicle (UAV) applications, the cargo is delivered and dropped autonomously by a UAV vertical takeoff and landing (VTOL) platform. In such a case, the UAV needs to sense the event of the cargo making contact with the ground in order to perform a safe and controlled detachment operation with respect to the cargo. 
     Management of these transitions has traditionally been approached by additional sling load sensors, camera optical aids, and other sensors. These solutions entail higher cost and multiple points of failure. Soft-weight-on-wheels algorithms have been suggested, however, such algorithms do not apply to slung load situations. 
     BRIEF SUMMARY 
     An embodiment is directed to a method comprising: obtaining data associated with at least one aircraft flight parameter when an aircraft is being operated in flight; processing the data to determine that the at least one aircraft flight parameter indicates a change in value in an amount greater than a threshold; and decoupling a load from the aircraft based on determining that the at least one aircraft flight parameter indicates the change in value in the amount greater than the threshold. 
     An embodiment is directed to an apparatus comprising: at least one processor; and memory having instructions stored thereon that, when executed by the at least one processor, cause the apparatus to: obtain data associated with at least one aircraft flight parameter when an aircraft is being operated in flight; process the data to determine that the at least one aircraft flight parameter indicates a change in value in an amount greater than a threshold; and cause a load to be decoupled from the aircraft based on determining that the at least one aircraft flight parameter indicates the change in value in the amount greater than the threshold. 
     An embodiment is directed to an aircraft comprising: a plurality of sensors configured to provide data pertaining to collective input, engine power, and shaft torque; and a control computer configured to: process the data to determine that at a weighted combination of the collective input, engine power, and shaft torque indicates a step change in value in an amount greater than a threshold magnitude as a function of time during flight; and cause a load to be decoupled from the aircraft based at least in part on determining that the weighted combination of the collective input, engine power, and shaft torque indicates the step change in value. 
     Additional embodiments are described below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure is illustrated by way of example and not limited in the accompanying figures in which like reference numerals indicate similar elements. 
         FIG. 1A  is a general perspective side view of an exemplary rotary wing aircraft; 
         FIG. 1B  is a schematic block diagram illustrating an exemplary computing system; 
         FIG. 2  is a block diagram of an exemplary system environment; 
         FIG. 3  is a block diagram of an exemplary system environment; and 
         FIG. 4  illustrates a flow chart of an exemplary method. 
     
    
    
     DETAILED DESCRIPTION 
     It is noted that various connections are set forth between elements in the following description and in the drawings (the contents of which are included in this disclosure by way of reference). It is noted that these connections in general and, unless specified otherwise, may be direct or indirect and that this specification is not intended to be limiting in this respect. In this respect, a coupling between entities may refer to either a direct or an indirect connection. 
     Exemplary embodiments of apparatuses, systems, and methods are described for detecting a load touchdown event. Detection of a load touchdown event may enable a safe transition to a stable load-detachment operation, wherein the load-detachment operation may be based on one or more autonomous or manual operations. Detection of a load touchdown event may occur without requiring the inclusion of additional or dedicated sensors. Existing flight control computer (FCC) parameters may be monitored to detect a touchdown event. Embodiments of the disclosure may provide for autonomous drop-off of cargo without a need for ground personnel to direct the aircraft descent till the touchdown event occurs. 
       FIG. 1A  illustrates an exemplary vertical takeoff and landing (VTOL) rotary wing aircraft  10 . The aircraft  10  is shown as having a dual, counter-rotating main rotor system  12 , which rotates about a rotating main rotor shaft  14 U, and a counter-rotating main rotor shaft  14 L, both about an axis of rotation  16 . Other types of configurations may be used in some embodiments, such as a single rotor system  12 . 
     The aircraft  10  includes an airframe  18  which supports the main rotor system  12  as well as an optional translational thrust system  24  which provides translational thrust during high speed forward flight, generally parallel to an aircraft longitudinal axis  26 . 
     A main gearbox  28  located above the aircraft cabin drives the rotor system  12 . The translational thrust system  24  may be driven by the same main gearbox  28  which drives the rotor system  12 . The main gearbox  28  is driven by one or more engines  30 . As shown, the main gearbox  28  may be interposed between the engines  30 , the rotor system  12 , and the translational thrust system  24 . 
     The aircraft may be configured to deliver a load or payload, such as cargo  20 . The cargo  20  may be coupled to the aircraft  10  via a sling  22 . When touchdown of the cargo  20  has occurred, or is imminent within a threshold distance of the ground or an object, the cargo  20  may be decoupled or detached from the sling  22 . 
     Although a particular counter-rotating, coaxial rotor system aircraft configuration is illustrated in the embodiment of  FIG. 1A , other rotor systems and other aircraft types such as tilt-wing and tilt-rotor aircrafts may benefit from the present disclosure. 
     Referring to  FIG. 1B , an exemplary computing system  100  is shown. Computing system  100  may be part of a flight control system of the aircraft  10 . The system  100  is shown as including a memory  102 . The memory  102  may store executable instructions. The executable instructions may be stored or organized in any manner and at any level of abstraction, such as in connection with one or more applications, processes, routines, procedures, methods, etc. As an example, at least a portion of the instructions are shown in  FIG. 1B  as being associated with a first program  104   a  and a second program  104   b.    
     The instructions stored in the memory  102  may be executed by one or more processors, such as a processor  106 . The processor  106  may be coupled to one or more input/output (I/O) devices  108 . In some embodiments, the I/O device(s)  108  may include one or more of a keyboard or keypad, a touchscreen or touch panel, a display screen, a microphone, a speaker, a mouse, a button, a remote control, a control stick, a joystick, a printer, a telephone or mobile device (e.g., a smartphone), a sensor, etc. The I/O device(s)  108  may be configured to provide an interface to allow a user to interact with the system  100 . 
     As shown, the processor  106  may be coupled to a number ‘n’ of databases,  110 - 1 ,  110 - 2 , . . .  110 - n . The databases  110  may be used to store data, such as data obtained from one or more sensors (e.g., accelerometers). In some embodiments, the data may pertain to an aircraft&#39;s measured altitude and sink rate. 
     The system  100  is illustrative. In some embodiments, one or more of the entities may be optional. In some embodiments, additional entities not shown may be included. In some embodiments, the entities may be arranged or organized in a manner different from what is shown in  FIG. 1B . For example, in some embodiments, the memory  102  may be coupled to or combined with one or more of the databases  110 . 
     Embodiments of the disclosure may be used in connection with a mission phase when a VTOL aircraft is in a controlled descent to drop or deposit slung-load cargo on the ground. Referring to  FIG. 2 , a block diagram of a system  200  in accordance with one or more embodiments is shown. The system  200  may be used to detect a touchdown event and command a decoupling or detachment of a payload. 
     The system  200  includes a trigger device  202  and a detection device  204 . The detection device  204  may monitor various parameters associated with an aircraft (e.g., a helicopter), such as collective input, engine power, and shaft torque, to detect the event or instances when the payload contacts the ground. The collective input, engine power, and shaft torque may demonstrate a step drop or change in value in the event of touchdown when an aircraft is being operated under controlled descent for vertical velocity or altitude. The step drop in value may be observed in an event another heavy payload—such as fuel tanks, heavy equipment, or several onboard personnel—departs the aircraft. In lieu of the use of the trigger device  202 , these events may also be detected if the detection device  204  is enabled. In this regard, the trigger device  202  may be configured to signal or enable the detection device  204  in only particular instances or under specified conditions. 
     The step drop in value described above may occur because the aircraft may require less power and torque to maintain constant vertical velocity or altitude at lower gross weight. In case of additional sensors that provide load position and location information, such as load force sensors, cameras, a laser-based sensor, etc., these sensors can be included in the detection device  204  to augment the detection. 
     The trigger device  202  may accept input from altitude or pressure sensors that indicate a location of the aircraft above ground with respect to sling length and payload height. If one or more sensors indicate that the bottom of the payload is within a threshold of the ground, the trigger device  202  may set an output trigger to enable the operation of the detection device  204 . 
     The trigger device  202  may include enable inputs from a mission management state machine or operator input so as to prevent a trigger in unwanted situations. For example, the trigger device  202  might not enable the detection device  204  in some instances to account for events in flight that could cause a change in one or more parameters measured by the detection device that might otherwise seem to indicate that a touchdown event has occurred. Such events could include a vibration associated with the collective, paratroopers exiting the aircraft, etc. 
     The detection device  204  may compute an event indicator function that is a combination of collective, engine power, and torque parameters. The function may be computed by scaling and weighing these parameters through a set of nonlinear gains and dynamic weights. Filters may be selected to reflect parameter dynamics. 
     Referring to  FIG. 3 , a system environment  300  for detecting a touchdown event is shown. The system  300  may be implemented as part of the system  200 . For example, the system  300  may be implemented in connection with the detection device  204 . One or more gains (e.g., nonlinear gains)  302   a ,  302   b , and  302   c , and/or transfer functions/filters  304   a ,  304   b ,  304   c , may be applied with respect to vertical performance variables or parameters, such as collective, engine power, and shaft torque, to generate an indication  306  of a touchdown event. In case of additional sensors that provide load position and location information, such as load force sensors, cameras, a laser-based sensor, etc., these sensors can be included in the detection device  204  to augment the detection. 
     The nonlinear gains  302   a ,  302   b , and  302   c  may be selected to incorporate deadbands and nonlinearities in the underlying parameters. Scaling and filtering may be performed to non-dimensionalize and time-align a step-change event in all parameters so that the event can be detected robustly. Filters and nonlinear gains might not be needed if the parameters do not have nonlinearities and occur in similar time-scale. There are many ways of designing these filters and tuning them as would be known to one of skill in the art—the system  300  captures all such instances and embodiments. 
     During a slung payload touchdown event, the output of the detection device  204  or the indicator  306  may undergo a step change from an airborne-regime to a ground-contact-regime. One or more thresholds may be selected, in terms of magnitude and/or time, to distinguish between the two regimes. In the event that the aircraft lifts off with the payload attached, the detection device  204  or the indicator  306  may experience a change in value corresponding to the airborne-regime. A detachment device  206  may process the output of the detection device  204  (or the indicator  306 ) to trigger detachment or disengagement of the payload. 
     The detachment device  206  may receive one or more inputs from an operator input data bus that may serve as an override. The operator may be a pilot, a remote pilot, an onboard operator, or a remote operator. The override may be used to selectively detach or retain a payload, potentially irrespective of the output of the detection device  204 . In some instances, the input driving the operator input data bus may be remotely located from the detachment device  206  or an aircraft. 
     In embodiments where load sensors are available in the sling system (e.g., sling  22 ), signals from the load sensors may serve as inputs to the detection device  204  or the indicator  306 . The signals from the load sensors may be weighted in proportion to the reliability of the load sensors. Incorporating the signals from the load sensors may enhance the robustness of payload touchdown detection. 
     Turning now to  FIG. 4 , a flow chart of an exemplary method  400  is shown. The method  400  may be executed by one or more systems, components, or devices, such as those described herein (e.g., the system  100 , the system  200 , and/or the system  300 ). The method  400  may be used to robustly and accurately detect a touchdown event in connection with a payload of an aircraft. 
     In block  402 , data associated with the operation of the aircraft may be obtained. For example, the data may pertain to operator input data, mission data, and/or data from one or more sensors. 
     In block  404 , the data of block  402  may be processed. As part of block  404 , the data may be filtered to remove extraneous data, to reduce the impact of noise on one or more measurements, or to obtain a data profile that more closely mirrors or resembles the physical world. 
     In block  406 , a determination may be made whether, based on the processed data of block  404 , a touchdown detection event should be enabled. A touchdown detection event might be enabled when a mission phase associated with the aircraft indicates as such and the aircraft is within a threshold distance of the ground or an object. If a touchdown detection event should be enabled (e.g., the “yes” path is taken out of block  406 ), flow may proceed from block  406  to block  408 . Otherwise (e.g., the “no” path is taken out of block  406 ), flow may proceed from block  406  to block  402 . 
     In block  408 , a determination may be made whether, based on the processed data of block  404 , a touchdown event has occurred. If so (e.g., the “yes” path is taken out of block  408 , flow may proceed from block  408  to block  410 ). Otherwise (e.g., the “no” path is taken out of block  408 ), flow may proceed from block  408  to block  402 . 
     In block  410 , a load or payload may be detached or decoupled from the aircraft. 
     The method  400  is illustrative. In some embodiments, one or more of the blocks or operations (or a portion thereof) may be optional. In some embodiments, the blocks or operations may execute in an order or sequence different from what is shown in  FIG. 4 . In some embodiments, one or more blocks or operations not shown may be included. For example, and as described above, an operator input may serve as an override to selectively detach or retain a load or payload. 
     Aspects of the disclosure may be applied in connection with a controlled vertical flight (phase). In some embodiments, controlled vertical flight may include descent at a fixed velocity or a stable altitude hold. Stable altitude hold may correspond to a controlled mode where a control algorithm or device may change a value to hold or maintain a particular value in the event of, e.g., payload detachment or alleviation. Controlled vertical flight may be used in connection with one or more of the examples described herein for selectively detaching or decoupling a payload. 
     In some embodiments, an estimate of gross weight changes associated with an aircraft may be provided. Such changes may be brought about by, e.g., load or fuel tank jettison events. Embodiments of the disclosure may be applied in connection with any “cause-effect” system that demonstrates a change in “effect” to detect a change in “cause” under constant velocity or position control. For example, aspects of the disclosure may be applied in connection with elevator or escalator load and motor torque. 
     As described herein, in some embodiments various functions or acts may take place at a given location and/or in connection with the operation of one or more apparatuses, systems, or devices. For example, in some embodiments, a portion of a given function or act may be performed at a first device or location, and the remainder of the function or act may be performed at one or more additional devices or locations. 
     Embodiments may be implemented using one or more technologies. In some embodiments, an apparatus or system may include one or more processors, and memory storing instructions that, when executed by the one or more processors, cause the apparatus or system to perform one or more methodological acts as described herein. Various mechanical components known to those of skill in the art may be used in some embodiments. 
     Embodiments may be implemented as one or more apparatuses, systems, and/or methods. In some embodiments, instructions may be stored on one or more computer-readable media, such as a transitory and/or non-transitory computer-readable medium. The instructions, when executed, may cause an entity (e.g., an apparatus or system) to perform one or more methodological acts as described herein. 
     Aspects of the disclosure have been described in terms of illustrative embodiments thereof. Numerous other embodiments, modifications and variations within the scope and spirit of the appended claims will occur to persons of ordinary skill in the art from a review of this disclosure. For example, one of ordinary skill in the art will appreciate that the steps described in conjunction with the illustrative figures may be performed in other than the recited order, and that one or more steps illustrated may be optional.