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Title:
IMPOSED LIMITS FOR LIMITING MOVEMENT OF A BOOM SYSTEM
Document Type and Number:
WIPO Patent Application WO/2012/030347
Kind Code:
A1
Abstract:
Methods, systems, and non-transitory computer-readable storage media are disclosed to limit movement of a boom system or other teleoperator in response to a control input. Control input is received at a controller of a boom system, where the control input commands movement of a portion of the boom system. A control action of the boom system responsive to the control input is determined. When the control input commands movement of the portion of the boom system to a first position within a first range, the control action implements the control input. When the control input commands movement of the portion of the boom system to a second position outside the first range but within a second range, the control action has a reduced response to the control input. When the control input commands movement of the portion of the boom system to an imposed limit, the control action commands the portion of the boom system to the imposed limit and prevents further movement of the boom system.

Inventors:
SPEER THOMAS E (US)
HATCHER JUSTIN C (US)
MUSGRAVE JEFFREY L (US)
Application Number:
US2010/047727
Publication Date:
March 08, 2012
Filing Date:
September 02, 2010
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
BOEING CO (US)
SPEER THOMAS E (US)
HATCHER JUSTIN C (US)
MUSGRAVE JEFFREY L (US)
International Classes:
B64D39/00
Domestic Patent References:
WO2010059155A12010-05-27
Foreign References:
EP1705116A22006-09-27
EP2058719A22009-05-13
US4264044A1981-04-28
Attorney, Agent or Firm:
WOO, Euclid et al. (P.O. Box 2515MC 110-SD5, Seal Beach California, US)
Download PDF:
Claims:
What is claimed is:

1. A method, comprising:

receiving control input at a controller of a boom system, the control input commanding movement of a portion of the boom; and

determining a control action of the boom system responsive to the control input, the control action including:

when the control input commands movement of the portion of the boom system within a first range, implementing the control input;

when the control input commands movement of the portion of the boom system beyond the first range but within a second range, reducing a response of the boom system to the control input; and

when the control input commands movement of the portion of the boom system to an imposed limit, moving the portion of the boom system to the imposed limit and preventing further movement of the boom system.

2. The method of claim 1, wherein the control input is received via the control device from a human operator.

3. The method of claim 2, further comprising providing mechanical resistance to the control input at the control device, and wherein a magnitude of the mechanical resistance increases as a magnitude of the control input is increased.

4. The method of claim 3, wherein the control device includes a joystick and the mechanical resistance is provided by one or more springs included in a base of the joystick.

5. The method of claim 1, wherein when the control input commands movement of the portion of the boom system to the imposed limit in a first direction, the control action does not respond to the control input in the first direction.

6. The method of claim 1, wherein the imposed limit is a subset of an actual mechanical limit of the portion of the boom system.

7. The method of claim 6, wherein the actual mechanical limit defines a first region in which the portion of the boom system is capable of moving, wherein the imposed limit defines a second region in which the portion of the movable boom system is allowed to move, and wherein the first region and the second region have different shapes.

8. The method of claim 1, wherein the boom system includes a video monitoring system and wherein the method includes automatically centering the portion of the boom system relative to a stowed position of the boom system when the portion of the boom system is moved into an area that is not viewable using the video monitoring system.

9. The method of claim 8, wherein the boom system includes an aerial refueling nozzle.

10. A system, comprising:

a boom system moveable by one or more actuators within actual mechanical limits in response to a control input and one or more control signals;

a boom control system, the boom control system being configured to limit movement of at least a portion of the boom system to imposed limits that are a subset of the actual mechanical limits, the boom control system comprising:

one or more boom position sensors configured to determine a position of the portion of the boom system; and

an imposed limits subsystem to reduce a magnitude of a control input when the portion of the boom system moves beyond a predetermined range of unrestricted movement and to negate the control input when the portion of the boom system reaches the imposed limits.

11. The system of claim 10, wherein the boom system is mounted on a vehicle.

12. The system of claim 11, wherein the boom system includes a refueling boom system mounted on an aircraft.

13. The system of claim 12, wherein the imposed limits restrain the movement of the boom system to guide the boom system in elevation and in azimuth between an operational position and a fully retracted position.

14. The system of claim 12, wherein the imposed limits restrain movement of the boom system in an area in which at least a portion of the boom system operates is not viewable by an operator of the boom system.

15. The system of claim 14, wherein the area in which at least a portion of the boom operates is not viewable by the operator of the boom system by direct visual examination and is not viewable by the operator of the boom system through the use of a camera system.

16. The system of claim 12, wherein the boom control system further comprises a control laws module configured to receive the control input and to determine the one or more control signals sent to the one or more actuators.

17. The system of claim 16, wherein the boom control system further comprises one or more additional modules configured to provide data used by the control laws module to determine the one or more control signals sent to the one or more actuators.

18. The system of claim 17, wherein the one or more additional modules include a boom dynamics module configured to monitor movement of the aircraft.

19. The system of claim 17, wherein the one or more additional modules include an inertial measurement unit configured to monitor movement of the portion of the boom system.

20. A non-transitory computer-readable storage medium comprising instructions executable by a processor to cause the processor to:

receive a control input at a controller of a boom system, the control input commanding a response of a portion of the boom system that is capable of operation within an actual mechanical limit; and

restrict the operation of the portion of the boom system to an imposed limit that is a subset of the actual mechanical limit by determining a control action responsive to the control input, the control action including:

implementing the control input when the control input commands a first response of the portion of the boom system in a first range within the imposed limit;

partially implementing the control input when the control input commands a second response of the portion of the boom system in a second range that is outside the first range and is within the imposed limit; and

ignoring the control input when the control input commands a third response of the portion of the boom system that is outside the imposed limit.

Description:
IMPOSED LIMITS FOR LIMITING MOVEMENT OF A BOOM SYSTEM

FIELD OF THE DISCLOSURE

The present disclosure is generally related to limiting movement of a boom system in response to a received control input.

BACKGROUND

In many situations it may be desirable that a boom system or other teleoperator offer a wide range of movement. By contrast, for other applications, a wide range of movement may create problems. As an example, many boom systems are controlled by operators who view the operation of the boom system through a window or via a monitor, permitting only a limited field of view by which to monitor the operation of the boom system. The boom system may be able to operate beyond that field of view. However, because the operator may not be able to monitor the movement of the boom system beyond the field of view, the boom system may have little or no use beyond the field of view.

Furthermore, when a boom system is moved beyond an operator's field of view, the movement of the boom system may result in harm. For example, a boom system is used on a tanker aircraft to extend a refueling nozzle to a second aircraft. When the refueling operation is complete, the boom system may be rotated back to a storage position that may be beyond the field of view of the operator. Unfortunately, if the refueling boom system has a range of movement that extends beyond the storage position, movement of the refueling boom system may result in the refueling boom system impacting the fuselage of the aircraft. Such an impact may damage the boom system or the refueling nozzle. Further, such an impact may result in the refueling boom system damaging the fuselage of the tanker aircraft. Further, engineering a boom system having actuators that only permit a range of movement in a limited range may be cumbersome and costly.

SUMMARY

Embodiments disclosed herein include methods, systems, and non-transitory computer- readable media storing instructions to limit movement of a boom system or other teleoperator in response to a control input. A controller or control system devices may receive operator input from the control device for the boom system to move the boom system in a chosen direction. The controller enables the boom system to move freely in the first direction in response to the operator input within a first range of movement. In a second range of movement beyond the first range, the controller reduces a response of the of the boom system to continued operator input in the chosen direction. The reduced response to the operator input thus requires more pronounced operator input to continue moving the boom system in the chosen direction. Beyond the second range, the controller places an imposed limit that prevents further movement of the boom system in the chosen direction, even when the boom system is capable of movement in the chosen direction beyond the imposed limit. After reaching the imposed limit, further operator input in the first direction at the control device results in no further movement of the boom system. The imposed limit may prevent undesirable movement of the boom system that may damage the boom system or other objects.

In a particular illustrative embodiment, a method includes receiving control input at a controller of a boom system, where the control input commands movement of a portion of the boom system. A control action of the boom system responsive to the control input is determined. When the control input commands movement of the portion of the boom system to a first position within a first range, the control action implements the control input. When the control input commands movement of the portion of the boom system to a second position outside the first range but within a second range, the control action has a reduced response to the control input. When the control input commands movement of the portion of the boom system to an imposed limit, the boom system is moved to the imposed limit and further movement of the boom system is prevented.

In another particular illustrative embodiment, a system includes a boom system by one or more actuators within actual mechanical limits in response to a control input and one or more control signals. A boom control system is configured to limit movement of at least a portion of the boom system to imposed operational limits that are a subset of the actual operational mechanical limits. The boom control system includes one or more boom position sensors configured to determine a position of the portion of the boom system. The boom control system also includes an imposed limits subsystem to reduce a magnitude of a control input when the portion of the boom system moves beyond a predetermined range of unrestricted movement and to negate the control input when the portion of the boom system reaches the imposed operational limits.

In still another particular illustrative embodiment, a non-transitory computer-readable storage medium includes instructions executable by a processor. In response to the instructions, a controller of a boom system receives a control input. The control input commands a response of a portion of the boom system that is capable of operation within an actual mechanical limit. Operation of the portion of the boom system is restricted to an imposed operational limit that is a subset of the actual mechanical limit by determining a control action responsive to the control input. The control action implements the control input when the control input commands a first response of the portion of the boom system in a first range within the imposed operational limit. The control action partially implements the control input when the control input commands a second response of the portion of the boom system in a second range that is outside the first range and is within the imposed operational limit. The control action ignores the control input by stopping a response of the portion of the movable boom system at substantially the imposed limit when the control input commands a third response of the portion of the boom system that is outside the imposed operational limit.

The system of the disclosure limits the movement of a boom system or other teleoperator to prevent damage to the boom system or another system operating in proximity of the boom system, particularly when the boom system is operated outside the field of view of the operator.

The features, functions, and advantages that have been described can be achieved independently in various embodiments or may be combined in yet other embodiments, further details of which are disclosed with reference to the following description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective diagram of an aircraft supporting a boom system operated subject to limits imposed by an embodiment of the present disclosure;

FIG. 2 is a block diagram of a particular illustrative embodiment of a control device and a controller that limit operation of a boom system in response to a control input received at the control device;

FIG. 3 is a diagram of a particular illustrative embodiment of ranges of unrestricted and restricted movement of a boom system and limits imposed on the movement of the boom system by a controller such as the controller of FIG. 2;

FIGs. 4-10 illustrate the response of a boom system under the control of the controller of

FIG. 2 to operator input applied to the control device based on the position of the boom system;

FIG. 11 is a state diagram of a particular illustrative embodiment of how the controller of

FIG. 2 responds to an input received at the control device based on the input and a current position of the boom system;

FIG. 12 is a flow diagram of a particular illustrative embodiment of a method to limit movement of a boom system in response to a control input; and FIG. 13 is a block diagram of a general purpose computer system operable to implement embodiments of computer-implemented methods and computer-executable program instructions in limiting movement of a boom system.

DETAILED DESCRIPTION

The present disclosure is directed to limiting movement of a boom system in response to a control input received at a control device of the boom system based on a position of the boom system. A controller receives operator input from the control device for the boom system. The controller enables the boom system to move freely in response to the control input within a first range of movement. In a second range beyond the first range, the controller only partially implements the control input by reducing a response of the boom system to the control input. In the second range, the boom system still responds to operator input at the control device, but a greater magnitude of operator input is required to move the boom system a same amount than is required in the first range. Beyond the second range, the controller restricts movement of the boom system to an imposed limit. Thus, even though the boom system may be capable of movement beyond the imposed limits, the controller negates or ignores further operator input when the boom system has reached the imposed limit. By using imposed limits, movement of the boom system may be limited to prevent undesirable movement of the boom system that may damage the boom system or other objects within the actual mechanical range of the boom system.

FIG. 1 depicts a first particular embodiment of an aerial refueling system including a tanker aircraft 101 having a boom system 100. The boom system 100 may include a section of fixed tube 102 supporting flight control surfaces, such as ruddevators 108, and a section of telescoping tube 104. The fixed tube 102 and the telescoping tube 104 support a nozzle 106 that is coupled to fuel tanks (not shown in FIG. 1) within the tanker aircraft 101. The boom system 100 may be adapted to provide in-flight refueling services to a refueling receiver 140. In the particular illustrative embodiment of FIG. 1, relative to a zero angle 130 set at horizontal, angular movement of the boom system 100 above the zero angle 130 toward the tanker aircraft 101 is designated as negative movement measured in negative degrees. Correspondingly, angular movement of the boom system 100 below the zero angle 130 away from the tanker aircraft 101 is designated as positive movement measured in positive degrees.

The boom system 100 may be controlled by an operator in the tanker aircraft 101 via control input applied to a control device 202, such as a joystick. Operator commands applied to the control device 202 may be limited or attenuated by the controller 212, as further described below, to reduce or block a response of the boom system 100 as at least a portion of the boom system 100 approaches and reaches an imposed limit, respectively. The control device 202 may control the ruddevators 108 and a hoist cable 110 that control a position of the fixed tube 102 and telescoping tube 104 of the boom system 100. In a particular embodiment, the ruddevators 108 may be used to steer the tubes 102 and 104 in elevation 114 and in azimuth 116. In a particular embodiment, the hoist cable 110 may be used to hold or to pull the fixed tube 102 of the boom system 100 into a stowed position relative to the tanker aircraft 101. In the stowed position, the boom system 100 may be received within a storage bay or other recess (not shown in FIG. 1) of the tanker aircraft 101. The boom system 100 may be equipped with a snubber 112 that acts as a shock absorber for the boom system 100 as it is received into the recess of the tanker aircraft 101.

During a refueling operation, the operator in the tanker aircraft 101 may use the control device 202 to fly the boom system 100 using the ruddevators 108 to place the nozzle 106 at a desired position relative to the refueling receiver 140. A boom camera 120 may provide the operator with a view of orientation of the nozzle 106 and the boom system 100 relative to the refueling receiver 140. The boom camera 120 may have a camera field of view 122 that captures only a portion of a potential full range of motion of the boom system 100. For example, in a particular embodiment the boom system 100 has a range of motion in elevation ranging from approximately -10 degrees 132 above a zero angle 130 (i.e., 10 degrees 132 above horizontal), to approximately +50 degrees 134 (i.e., 50 degrees below horizontal). In this embodiment, the camera field of view 122 may not encompass the zero angle 130, let alone the range of motion above the zero angle 130 within the movable range of the boom system 100 where, for example, the boom system 100 may be moved into a stowed position. However, the camera field of view 122 may encompass the maximum deployment range of the boom system 100 (i.e., at +50 degrees 134) and beyond in the downward direction. For example, the boom camera 120 may include more than one camera such as used in a boom aerial refueling camera system (BARCS) to provide a stereoscopic narrow field view of the nozzle 106 and the boom system 100 relative to the refueling receiver 140. Although the boom camera 120 may provide high resolution or stereoscopic vision to assist the operator in positioning the nozzle 106 for refueling, the boom camera 120 may not provide assistance to the operator in stowing the boom system 100 or in other operations outside the camera field of view 122.

During operation, unexpected situations or emergency situations may arise which cause the operator to provide control input to the boom system 100 that could be dangerous to the refueling receiver 140 or the tanker aircraft 101. For example, if the boom system operator retracts the boom system 100 too quickly, the snubber 112 or other parts of the boom system 100 may strike the tanker aircraft 101, potentially causing damage to the tanker aircraft 101. In another example, the operator may provide input that causes the boom system 100 to fly to the mechanical limits of the boom system 100 in azimuth 116 that may cause damage to the boom system 100 or to the tanker aircraft 101 where the boom system 100 is mounted on the tanker aircraft 101.

For example, the boom system 100 may be capable of flying upward in elevation 114 at a rate of approximately 10 degrees elevation per second. Thus a boom operator may fly from a 30 degree down angle, a typical position for refueling the refueling receiver 140 to a stowed angle that is 10 degrees above the zero angle 101 in approximately four seconds. In another example, the boom system 100 may have a plus or minus 20 degree range of motion in azimuth 116 at most airspeeds of the tanker aircraft 101. However, plumbing within the boom system 100 may be stressed when the boom system 100 flies outside plus or minus 10 degrees from the nominal position. Thus, flying at extreme angles in azimuth 116, such as plus or minus 20 degrees in azimuth 116 may put unwarranted stress on plumbing of the boom system 100 as well as a pivot system of the boom system 100. Flying at lower operational angles in azimuth 116 avoids reaching these mechanical risk limits and fatiguing the system.

In a particular embodiment, a boom control system (not shown in FIG. 1) may be implemented to set imposed limits that remove control stick authority from the boom operator by opposing movement commands in control logic when the boom system 100 approaches undesirable [ temper discussions on failures] positions in elevation 114 or in azimuth 116. The imposed limits reduce a response of the boom system 100 to continued operator input once the boom system 100, or at least a portion of the boom system 100, has moved into an imposed restricted movement range. In a particular embodiment, the control system reduces a magnitude of the control input that is provided to the boom system 100. Then, when the boom system 100 reaches the imposed limits, the control system negates or rejects further operator input at the control device 202. Thus, even if the operator continues to provide input to move the boom system 100 beyond the imposed limits but within the actual mechanical limit of the boom system 100, the control system may prevent any further movement of the boom system 100 and may only permit the boom system 100 to respond to commands to move the boom system 100 away from the imposed limits. In other words, the imposed limits may completely remove control authority from the boom operator at particular points in elevation 114 or azimuth 116 to prevent the boom system 100 from moving past those particular points in elevation 114 or azimuth 116. Thus, for example, the control system may remove control authority to move boom system 100 outside of a predetermined channel as the boom system 100 is drawn to a stowed position to prevent damage to the boom system 100. The control system also may prevent the boom system 100 from being retracted beyond the stowed position (if the actual mechanical limits extend beyond the stowed position) to prevent damage to the fuselage of the tanker aircraft 101. In a particular embodiment, the imposed limits may be adjustable based on the particular type of boom system 100, tanker aircraft 101, or another situation, such as by adjusting the imposed limits for a particular tanker aircraft 101 operating with a particular refueling receiver 140.

FIG. 2 depicts a particular embodiment of an imposed limit control system 200 to control a boom system such as the boom system 100 mounted on the tanker aircraft 101 as illustrated in FIG. 1. The boom system also may include a boom system mounted on another aircraft or on a land-based, water-based, or space-based vehicle. Also, the boom system may be mounted on a stationary base. The boom control system 200 includes the control device 202 of FIG. 1 configured to receive input from a boom operator or other operator. For example, the control device 202 may include a joystick or other input device 203 that allows the boom operator to provide elevation control input 204 and azimuth control input 206. In a particular embodiment, the joystick 203 is mounted via a spring 205 to a base 208. The spring 205 provides mechanical resistance to control input applied at the joystick 203. The mechanical resistance applied to the joystick 205 may be proportional to the control input received. In the example of FIG. 2, the farther the joystick 203 is moved in one direction, the greater will be the compression of the spring 205 between the joystick 203 and the base 208, and the greater the mechanical resistance applied to the joystick 203 may be.

The control device 202 sends a control input signal 210 to a summing junction 220. The summing junction 220 combines the control input signal 210 with a feedback loop and sends a signal to boom control laws 230. The boom control laws 230 include fly-by- wire controller information related to the boom system 100. For example, the boom control laws 230 include information used to determine a first control signal 232 to position the ruddevator actuators 240 to control elevation 1 14 and azimuth 116 of the boom system 100 (FIG. 1). A first control signal 232 is sent to the ruddevator actuators 240 and to boom dynamics 250. The boom dynamics 250 adjust or compensate for overall dynamics of the tanker aircraft 101 in governing movement of the ruddevators 108. A feedback loop is provided with input from one or more inertial measurement unit sensors 260 to generate a second control signal 262 as feedback to the boom control laws 230. The inertial measurement unit sensors 260 provide input regarding an actual angular rate and linear acceleration of movement of the boom system 100. Additionally, output from the boom dynamics 250 is provided to boom position sensors 270 which gather information about a position of the boom system 100 in elevation 114 and in azimuth 116.

Output from the boom position sensors 270 also is provided to imposed limits 280 which include laws governing imposed limits applied to the boom system 100. For example, the imposed limits 280 define an unrestricted operator control region, a restricted region, and an imposed limit that prevents further movement of the boom system. An output of the imposed limits 280 is fed back to the summing junction 220 where the output of the imposed limits offsets or negates at least a portion of the control input signal 210 generated by the control device 202. As further described with reference to FIGs. 3-10, when the boom system (or at least a portion of the boom system) 100 operates in a defined, unrestricted range, an operator may move the boom system with full control (or stick authority). The only opposition to or limiting of the operator input is mechanical input of the spring 205 that is deformed or compressed between the joystick 203 and the base 208 when the joystick 203 is moved. According to one particular embodiment, when a portion of the boom system 100 moves beyond the unrestricted range into a restricted range, the output of the imposed limits 280 received at the summing junction 220 reduces or partially offsets the control input signal 210 so that a greater or more pronounced operator input is required at the joystick 203 to generate a control input signal 210 that may at least partially overcome the output of the imposed limits 280 at the summing junction 220. When the portion of the boom system 100 reaches limits established for the boom system 100, the imposed limits 280 entirely offsets or blocks the control input signal 210. As a result, no matter to what extent an operator moves the joystick 203 in a direction where the portion of the boom system 100 has reached predefined imposed operational limits, the output of the imposed limits 280 applied by the summing junction 220 cancels the control input signal 210.

In operation the control input signal 210 may be received at the control device 202. The control input signal 210 may command movement of a portion of a boom system 100 in a first direction, for example in elevation 114 or in azimuth 116, as illustrated in FIG. 1. The controller input signal 210 may be provided to a controller 212 which may include one or more processors, one or more computing systems, and so forth. The controller 212 may determine a control action responsive to the control input signal 210. For example, the control action may include sending feedback to the control device 202 providing a control signal to the ruddevator actuators 240 or providing other control input, such as retracting the hoist cable 110 coupled to the boom system 100 as illustrated in FIG. 1.

In a particular embodiment, when the control input 210 commands movement of the boom system 100 to a position within a first range, the control action may be implemented without adjustment or limitation by the controller 212. When the control input commands movement of the boom system 100 to a second position that is outside the first range and that is within a second range, the controller 212 may reduce the control action (i.e., a response of the boom system) to the control input signal 210. When the control input signal 210 commands movement of the boom system 100 to at point at or beyond an imposed operational limit, the boom system 100 may be moved to the imposed operational limit but no further control input in that direction may be permitted via the control device 202. In other words, once the boom system 100 reaches the imposed operational limit in a particular direction, the boom system 100 is prevented from further movement in that particular direction and, as a result, stick control authority may be removed from the control device 202 in that direction.

FIG. 3 depicts a first particular embodiment of boom actual mechanical limits and imposed limits according to a particular illustrative embodiment. For the purpose of this FIG. 3, an actual mechanical limit 330 is illustrated as a dashed box. An imposed limit 300 is circumscribed within the actual mechanical limit 330. An unrestricted movement range 310 is illustrated as a first range within the imposed limit 300. A restricted movement range 320 is positioned outside the unrestricted movement range 310 and extends from a restricted movement threshold 322 to the imposed limit 300.

As described with reference to FIG. 2, the boom system 100 (FIG. 1) may be moved freely by an operator using the control device 202 (FIG. 2) when the boom system 100 or a designated portion of the boom system 100 is positioned with the unrestricted movement range 310. However, once the operator causes the boom system 100 or a portion of the boom system 100 to cross the restricted movement threshold 322 into the restricted movement region, 320, the control input signal 210 (FIG. 2) is partially offset by the imposed limits 280 within the controller 212. As a result, movement of the boom system 100 in response to a control input is reduced, and a greater degree of control input may be required to cause the boom system 100 to move with the same speed. When the boom system 100 or the designated portion of the boom system 100 reaches the imposed limit 300, the control input signal 210 is canceled by the boom limits 280. Thus, although the actual mechanical limit 330 may significantly exceed the imposed limits 300 selected, the controller 212 will prevent movement of the boom system 100 beyond the range of the imposed limit 330.

For example, the actual mechanical limit 330 may have an azimuthal range limit 354. The imposed limit 300 may have an azimuthal imposed limit range 352 that is narrower than an operational limit range 354 at maximum elevation. The unrestricted movement range 310 may have an unrestricted azimuthal range 350 at maximum elevation that is narrower than the imposed limit range 352. Additionally the imposed limit 300 and the restricted movement threshold 322 may vary at different elevations. For example, by narrowing the unrestricted movement range 310 and the imposed limit 330 at negative elevations as the boom system 100 (FIG. 1) is moved toward a stowed position, the boom system 100 may be forcibly guided into a centered position relative to a vehicle or other body on which the boom system is mounted (e.g., the tanker aircraft 101 of FIG. 1). Narrowing the permitted range of movement of the boom system 100 may force the boom system 100 into a center position beneath the stowed position 362 to ensure no damage is inflicted on the boom system 100, the vehicle (such as the tanker aircraft 101), or other body on which the boom system 100 is mounted.

The actual mechanical limit 330 may range from the stowed position 362 to a maximum positive elevation 344. However, the imposed limit 300 may have a positive elevation imposed limit 342 that is at a lesser positive elevation relative to the zero angle 130 (as also shown in FIG. 1) than the maximum positive elevation actual mechanical limit 344. Further, the unrestricted movement range 310 may have a positive elevation restricted movement threshold 340 that is at a positive elevation less than the positive elevation imposed limit 342 relative to the zero angle 130. Thus, within the unrestricted movement range 310, the boom operator may fly the boom system 100 via control inputs without restriction. However, normal flight control feedback in fly-by- wire systems may be provided to assist the boom operator with proper flight inputs. By contrast, within the restricted movement range 320, control signals resulting from the control inputs provided by the boom operator may be reduced. In other words, extreme inputs may be reduced to constrain the boom operator from extending the boom system 100 beyond a chosen operational range specified by the imposed limit 300. As described below with reference to FIGs. 4-10, the reduced operator control may result in the operator receiving some feedback, such as having to provider a greater degree of input, as the boom system is nearing the imposed limit 300. Once the boom system 100 reaches the imposed limit, stick authority may be lost, thereby preventing the operator from moving the boom system 100 beyond the imposed limit 300. FIGs. 4-10 depict how an embodiment of the controller 212 of FIG. 2 restricts operator input based on the position of the boom system within the unrestricted movement range 310, the restricted movement range 320, and the imposed limit 300 of FIG. 3. FIG. 4 illustrates a first situation in which a control device 202 is not subject to any control input from an operator. The boom system 100, or the portion of the boom system 100 whose position is being monitored, is at a first or current position 412. Because no control input is applied to the control device 202, the boom system 100 remains at the first position 412. Note that the first position 412 of the boom system 100 is in the unrestricted movement range 310. Also, because no control input is applied at the control device 202, the spring 205 (FIG. 2) remains at an uncompressed position 405.

FIG. 5 illustrates a second situation in which a first control input 504 from a boom operator is applied to the control device 202. In response to a first control input 504, the boom system 100 moves according to a control action 514 from the first position 412 toward a position at a greater positive elevation. According to a particular illustrative embodiment, because the position of the boom system 100 is in the unrestricted movement range 310, the control device 212 fully implements the first control input 504. The first control input 504 compresses the spring 205 in a direction to a spring at first compression position 505. Compressing the spring to the first compression 505 results in a first resistance 508 being applied to the joystick 203 in an opposite direction to the first control input 504.

Referring to FIG. 6, the control input 504 (in a same direction and of a same magnitude as shown with regard to FIG. 5), continues to be applied to the control device 202. As shown in FIG. 6, boom system 100 has been moved from the first position 412 to a second position 612 within unrestricted movement range 310. Because the first control input 504 continues to be applied, the boom system 100 continues to move in response to the first control input 504 at a same rate within the unrestricted range 310. In other words, because the boom system 100 continues to operate in the unrestricted movement range 310, the first control input 504 continues to be fully implemented without a reduction in response. As is the case in the example of FIG. 5, the application of the first control input 504 to the joystick 203 compresses the spring to a position at first compression 505 that results in the first resistance 508 being applied to the joystick 203.

FIG. 7 illustrates a case in which the boom system 100 has been moved to a third position 712 at an edge or boundary of the restricted movement range 320 (i.e., the restricted movement threshold 322 of FIG. 3). A second control input 704 continues to direct the boom system 100 to move in a same direction of movement as shown in FIGs. 5 and 6, with the boom system 100 moving through the restricted movement range 320 toward a fourth position 716 adjacent the imposed limit 300.

In response to the position of the boom system 100 passing into the restricted movement range, the controller 212 (FIG. 2) reduces a response of the boom system 100 to a control input. Thus, for example, if the control input 504 (FIGs. 5 and 6) continued to be applied to the joystick 203, the boom system 100 would respond more slowly. If the operator wishes to move the boom system 100 at the same rate, the operator must increase a magnitude of the control input. Referring to FIG. 7, a second control input 704 is of a greater magnitude (i.e., the joystick 203 is pushed farther forward than in the first control input 506) to cause the boom system 100 to move more rapidly as a result of the reduced response. In response to the second control input 704, the spring 205 (FIG. 2) is now compressed to a second compression 706 which is greater than the compression of the spring at the first compression 505 (FIGs. 5 and 6). The increase compression of the spring at the second compression 706 results in a second resistance 708 being applied to the joystick 203 that is greater than the first resistance 508. In sum, after the boom system 100 reaches the restricted movement range 320, the operator will have to apply an increased control input to the joystick 203 to cause the boom system 100 to move in a way that would have required a lesser control input in the unrestricted movement range 310.

FIG. 8 illustrates a case at which the boom system 100 has reached the imposed limit 300. In response to reaching the imposed limit 300, the boom system 100 may not be moved further in that same direction. Following the application of the first control input (FIGs. 5 and 6) and the second control input 704 (FIG. 7), the boom system 100 has reached a fifth position 818 of the imposed limit 300, at which point the boom system 100 moves no further in that same direction.

Referring to FIG. 2, once the boom system 100 reaches the imposed limit 300, the imposed limits 280 of the controller 212 supply a signal to the summing junction 220 that offsets the control input signal 210 received from the control device 202. Thus, the boom control laws 230, the ruddevator actuators 240, and other components downstream of the summing junction 220 do not receive a further control signal. In other words, by operation of the controller 212, when the boom system 100 reaches the imposed limit 300, the controller 212 cuts off further control input in the same direction as though the operator had ceased further input. As shown in FIG. 8, the operator continues to move the joystick 203, but the controller 212 has reduced the control input to zero 804, leaving the operator with no stick authority. The spring at the second compression 706 will continue to oppose operator input applied by the joystick 203. In any case, once the imposed limit 300 is reached, the boom system 100 may not move beyond the imposed limit 300.

Referring to FIG. 9, the operator applies a third control input 904 in an opposite direction, pulling back on the joystick 203 to move the boom system 100 toward the stowed position. Application of the third control input 904 to the joystick results in the spring reaching a third compression 906 which results in a third resistance 908 being applied to the joystick 203. With reference to FIGs. 5-10, note that the resistances 508, 708, and 908 resulting from compression of the spring always oppose the control inputs 504, 704, and 904.

In response to application of the third control input 904, the boom system 100 moves to a sixth position 912. Referring to FIG. 8, movement of boom system 100 was stopped in elevation at the imposed limit 300. Nonetheless, even when the boom system 100 reaches an imposed limit in one direction, the boom system 100 may still be movable in one or more other directions. For example, as shown in FIG. 9, the boom system 100 is responsive to the third control input 904 that directs the boom system 100 away from the imposed limit. In addition, movement of the boom system 100 may be restricted in one direction while movement of the boom system 100 may not be restricted in another direction. For example, the sixth position 912 of the boom system results in a partially restricted boom system response. The boom system 100 abuts the restricted movement range 320 in azimuth, but not in elevation. Thus, the boom system 100 may be moved freely in elevation (or in azimuth if moved in an opposite direction in azimuth), but further movement in azimuth into the restricted movement range 320 will result in a reduced response of the boom system 100.

FIG. 10 shows unrestricted response of the boom system 100 at a seventh position 1014 in response to continued application of the third control input 904. If application of the third control input 904 directed the boom system into the restricted movement range 320 and then the imposed limit 300, the controller 212 (FIG. 2) would have attenuated or reduced the response of the boom system 100 to components of the third control input 904 that would have directed the boom system 100 beyond the imposed limit 300. However, the shape of the unrestricted movement range 310, the restricted movement range 320, and the imposed limit permit a movement of the boom system 100 toward a negative elevation even when further movement in azimuth may be blocked. Thus, if the operator continues to apply the third control input 904, the controller 212 will reduce or block response of the boom system 100 at the imposed limit 300 in azimuth but will continue to respond to a portion of the third control input 904 that directs the boom system 100 in an acceptable direction. In other words, the boom system 100 will continue to move in negative elevation in response to a component of the third control input 904 that moves the boom system 100 in negative elevation toward a stowed position but will oppose movements in azimuth that are not desired at the stowed position. The boom system 100 may be out of view of the boom camera 120 (FIG. 1) as the boom system 100 approaches the stowed position. However, restriction of movement of the boom system 100 within the imposed limit 300 automatically centers the boom system 100 as the boom system 100 is moved into the stowed position.

FIG. 11 is a state diagram 1100 of a particular embodiment of controlling a boom system 100 (FIG. 1) based on a current position of the boom system 100 and a control input received. The states 1110, 1120, and 1130 are determined by the current position of the boom system. The state diagram 1100 includes three states based on the position of the boom system: in the first state 1110, when the boom system is in an unrestricted movement range 310 (FIG. 3), movement of the boom system 100 is not restricted and any control input is fully implemented. In the second state 1120, when the boom system 100 is in a restricted movement range 320 (FIG. 3), movement is permitted but restricted by the reduced response of the boom system 100 to the control input. In the third state 1130, when the boom system 100 reaches the imposed limit 300 (FIG. 3), further movement is blocked. The arrows 1112, 1114, 1116, 1122, 1124, 1126, and 1132 represent state changes in response to control inputs applied to a control device. The state diagram 1100 may be replicated for each direction of possible movement. Thus, the state diagram 1100 may represent the states of movement possible as the boom system moves toward a maximum positive elevation, while additional state diagrams would apply for movement toward a maximum negative elevation and for maximum azimuthal movements.

In the first state 1110 when the boom system 100 is in the unrestricted movement range, and the control device input directs the boom system 100 to move within the unrestricted movement range at 1112, the boom system 100 remains in the first state 1110 and movement of the boom system 100 is not restricted. However, when in the first state 1110, and the control device input directs the boom system 100 to move within the restricted movement range at 1114, the boom system 100 enters the second state 1120 in which responsiveness of the boom system 100 to operator input is reduced.

In the second state 1120 when the boom system 100 is in the restricted movement range, and the control device input directs the boom system 100 to move within the restricted movement range at 1122, the boom system 100 remains in the second state 1120 and movement of the boom system 100 is permitted to continue but at a continued reduced response to the control input. However, when the boom system 100 in the second state 1120, and the control device input directs the boom system 100 to move to the imposed limit at 1124, the boom system 100 enters the third state 1130 in which movement of the boom system 100 is blocked in the direction represented by the state diagram 1100.

In the third state 1130 when the boom system 100 is at the imposed limit and the control device input continues to direct the boom system 100 against the imposed limit at 1132, the boom system 100 remains in the third state 1130 and movement of the boom system 100 continues to be blocked. However, when the boom system 100 is in the third state 1130, and the control device input directs the boom system 100 to move away from the imposed limit at 1 126, the boom system 100 enters the second state 1120 in which movement of the boom system 100 is permitted but subject to a reduced response to the control input. Correspondingly, when the boom system 100 is in the second state 1120, and the control device input directs the boom system 100 to move away from the restricted movement range into the unrestricted movement range at 1116, the boom system 100 enters the first state 1110 in which movement of the boom system 100 is permitted with full responsiveness to the control device. Thus, whether the boom system is permitted unrestricted movement or restricted movement or the boom system is prevented from movement in a particular direction is continuously determinable based on a position of the boom system 100 and a direction of a control device input.

FIG. 12 is a flowchart of the first particular embodiment of a method 1200 of controlling position of a movable boom system. The method 1200 includes receiving control input at a controller of a movable system, at 1202. The control input may command movement of a portion of the movable boom system in a first direction. For example, the movable system may include at least a portion of a movable boom system of a refueling tanker aircraft, such as the tanker aircraft 101 of FIG. 1. The control input may command movement in elevation 114 (positive or negative) or in azimuth 116 (left or right) as illustrated in FIG. 1. The method 1200 may also include determining a control action responsive to the control input, at 1204. For example, the control input may be provided to a controller such as the controller 212 of FIG. 2.

The method 1200 may include determining whether the control input commands movement of the portion of the boom system to a first position within a first range, at 1206. When it is determined that the movement directed by the control input is within the first range, the method 1200 includes implementing the control input, at 1208. When it is determined at 1206 that the movement directed by the control input is not within the first range but is determined to be within a second range, at 1212, the method includes reducing a response of the boom system to the control input, at 1212. When it is determined at 1210 that the movement directed by the control input is not within the second range and, thus, is at an imposed limit, movement of the portion of the boom system is stopped at the imposed limit, at 1214. Upon reaching the imposed limit, stick authority may be removed, indicating to the operator that the operator is not able to move the movable boom system beyond the imposed limit.

FIG. 13 is a block diagram of a general purpose computing environment 1300 operable to implement embodiments of computer-implemented methods and computer-executable program instructions in controlling the movement of a boom system or other movable system in response to control input as described with reference to FIGs. 1-10. In one illustrative embodiment, a computing system 1310 includes an agent, which may be autonomous, or the computing system 1310 may direct a human operator. The computing system 1310 includes at least one processor 1320. Within the computing system 1310, the processor 1320 communicates with a system memory 1330, one or more storage devices 1340, one or more input/output devices 1350, and one or more network interfaces 1380 through which the computing system 1310 communicates with one or more other computer systems 1390.

The system memory 1330 may include volatile memory devices, such as random access memory (RAM) devices and nonvolatile memory devices such as read-only memory (ROM), programmable read-only memory, and flash memory. The system memory 1330 typically includes an operating system 1332, which may include a basic/input output system for booting the computing system 1310 as well as a full operating system to enable the computing system 1310 to interact with operators, other programs, and other computer systems 1390. The system memory 1330 also typically includes one or more application programs 1334, such as programs that direct the autonomous agent in the performance of actions that are part of the tasks that, in turn, may be part of a shared plan. The system memory 1330 also may include program data 1336, such as status information for the local agent or one or more other agents, as previously described.

The processor 1320 also communicates with one or more storage devices 1340. The storage devices 1340 may include nonvolatile storage devices such as magnetic disks, optical disks, or flash memory devices.

The processor 1320 communicates via one or more input/output interfaces 1350 with one or more input/output devices 1360 (i.e., such as the control device 502) that enable the computing device 1310 to interact with an operator. The input/output devices 1360 may include keyboards, pointing devices, microphones, speakers, and displays. The processor 1320 also communicates with one or more network interfaces 1380 that enable the computing device 1310, as used in an agent, to communicate with other agents.

Not all of the components or devices illustrated in FIG. 13 or otherwise described in the previous paragraphs are necessary to support implementations of the present disclosure. For example, a device may include an integrated system memory and storage device including a flash memory configured to store all programs and data for operation of a system. In addition, if all input and output is communicated via the network interfaces 1380, a system may not include any other input/output interfaces 1350 or input/output devices 1360.

The illustrations of the embodiments described herein are intended to provide a general understanding of the structure of the various embodiments. The illustrations are not intended to serve as a complete description of all of the elements and features of apparatus and systems that utilize the structures or methods described herein. Many other embodiments may be apparent to those of skill in the art upon reviewing the disclosure. Other embodiments may be utilized and derived from the disclosure, such that structural and logical substitutions and changes may be made without departing from the scope of the disclosure. For example, method steps may be performed in a different order than is shown in the figures or one or more method steps may be omitted. Accordingly, the disclosure and the figures are to be regarded as illustrative rather than restrictive.

Moreover, although specific embodiments have been illustrated and described herein, it should be appreciated that any subsequent arrangement designed to achieve the same or similar results may be substituted for the specific embodiments shown. This disclosure is intended to cover any and all subsequent adaptations or variations of various embodiments. Combinations of the above embodiments, and other embodiments not specifically described herein, will be apparent to those of skill in the art upon reviewing the description.

The Abstract of the Disclosure is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing Detailed Description, various features may be grouped together or described in a single embodiment for the purpose of streamlining the disclosure. This disclosure is not to be interpreted as reflecting an intention that the claimed embodiments require more features than are expressly recited in each claim. Rather, as the following claims reflect, the claimed subject matter may be directed to less than all of the features of any of the disclosed embodiments.