Abstract:
A method for at least partially de-icing an aircraft by applying a de-icing fluid through a nozzle ( 10 ) is disclosed. The method involves the steps of: measuring a distance to an outside surface of the aircraft, applying the distance in an evaluation, controlling the position and/or the orientation of the nozzle ( 10 ) according to the evaluation, and applying the de-icing fluid at least a part of the outside surface trough the nozzle. In addition, a system for performing the de-icing method is also revealed.

Description:
FIELD OF THE INVENTION  
       [0001]    The present invention generally relates to de-icing of an aircraft wing, and in particular to the application of the de-icing fluid. More specifically, the present invention relates to a de-icing method involving a nozzle and a distance sensor, where the latter is employed to determine the distance between the nozzle and the aircraft wing. 
       DESCRIPTION OF THE RELATED ART 
       [0002]    Under freezing conditions, the de-icing of an aircraft may be critical for its flight performance. Ice may degrade the ability of an aircraft wing to generate a lift force. For an aircraft in self propelled motion, pieces of ice may come loose and cause damage by hitting the tail or tail fins, or by being sucked into an engine or hitting a propeller, which may have catastrophic effects. Further, ice may prevent important control surfaces, such as flaps and elevators, from operating properly. 
         [0003]    Here the term de-icing means the removal of ice or the prevention of ice to form. The term de-icing may also mean a combination of a removal of ice and prevention of ice to form. One method of de-icing involves a heating of the ice. In practise, this is commonly achieved by subjecting the ice to a hot fluid, usually a liquid. Another method involves the application of chemicals to the ice to lower the freezing point of water, the chemicals typically being monopropylene glycol or ethylene glycol. The methods of heating and applying a chemical may be employed separately, i.e. in two separated steps, or in combination, i.e. in a single step. The liquid for the removal of ice commonly has a low viscosity, whereby it easily runs off the surface of an aircraft wing after being applied. The liquid for prevention of ice to form may have a high viscosity, whereby it sticks to the surface of the aircraft wing and prevents the build-up of a layer of ice. Further, the term de-icing may also mean the removal of frost or snow, or the prevention of frost or a layer snow to form. For example, a heated glycol and water mixture is commonly employed for removing ice, frost and snow. 
         [0004]    The de-icing fluid is commonly applied to an aircraft wing by a nozzle. The distance between the nozzle and the surface of the wing is important for both the temperature of the fluid, as a heated fluid cools when it travels between the nozzle and the wing, and for the amount of fluid per unit area and unit time that is applied to the wing, as the nozzle commonly disperses the fluid. For this reason, the distance between the nozzle and the surface is an important factor to control for an efficient de-icing. 
         [0005]    In EP1775218A1 a vehicle for de-icing an aircraft is disclosed, where the vehicle in question is capable of automatically achieving a spraying pattern. However, the distance between the nozzle and the aircraft body or aircraft wing is not considered in the de-icing. 
       OBJECT OF THE INVENTION 
       [0006]    An object according to the present invention is to achieve a more efficient de-icing of aircraft wings. An advantage according to the present invention is that it allows for a reduction of the amount of de-icing fluid used and of the time needed for de-icing. A particular feature of the present invention is that it allows for a de-icing that takes the distance between the nozzle applying the de-icing fluid and the wing surface into account when controlling the position of the nozzle. An additional object according to the present invention is to provide safer de-icing techniques avoiding or reducing the risk for accidents to occur. 
       SUMMARY/DISCLOSURE OF INVENTION 
       [0007]    The above object, the above advantage and the above feature, together with numerous other objects, advantages and features, will be evident from the detailed descriptions given below of preferred embodiments according to the present invention. The objects, advantages and features are according to a first aspect of the present invention obtained by a method for at least partially de-icing an aircraft by applying a de-icing fluid through a nozzle, the method comprising the steps of: measuring a first distance along a measurement direction from a first location relative to the nozzle to a physical outside surface of the aircraft, applying the first distance in a first evaluation, controlling the position and/or the orientation of the nozzle according to the first evaluation, and applying the de-icing fluid to at (east a part of the physical outside surface trough the nozzle. 
         [0008]    The nozzle may be a spray nozzle for distributing a liquid over a surface. Liquid projected from the nozzle may on a flat surface define a circle, an ellipse, a rectangle, a square, a triangle, or combination thereof. The nozzle position defined by the nozzle may be relative to a fix point on the airplane, to a fix point on the ground, to a distant transponder, or to a fix point on a vehicle chassis providing ground support for the support arm. Similarly, the nozzle orientation may be defined by the nozzle position relative to a fix point on the airplane, to a fix point on the ground, to a distant transponder, to a fix point on vehicle chassis providing ground support for the support arm. Alternatively, the nozzle orientation may be relative to the support arm. 
         [0009]    The nozzle orientation may be defined as the principal fluid application direction of the nozzle, i.e. the general direction of fluid expelled from the nozzle. If pointed at a planar surface and a liquid projected from the nozzle defines an area on the surface, the fluid application direction may be defined by a line between the nozzle position and the geometric centre of this area. Alternatively, the fluid application direction may be defined as the general or average direction of the spray from the nozzle. 
         [0010]    The first location may correspond to the physical location of a sensor, or to a location derived by a sensor. For example, if a triangulation sensor is employed, the first location may correspond to the position of the emitter and the measurement direction may correspond to the emitted measurement signal. Alternatively, the first location may correspond to the position of the receiver and the measurement direction may correspond to the reflected measurement signal 
         [0011]    The measurement direction defined by the distance sensor may be the intended principal direction for measurements by the instrument or sensor employed. Alternatively, the measurement direction may be defined relative to the nozzle orientation or the fluid application direction. For example, the fluid application direction and the measurement direction may be parallel. 
         [0012]    The physical outside surface of the aircraft may be on the wings, the tails, and/or the fuselage. Preferably, the physical outside surface is the upper side of the wing of an aircraft. 
         [0013]    By the first location and the nozzle defining a first separation between them means that they together define a derivable separation and a derivable relative positioning, e.g. a separation that can be measured physically. The first position has a given position relative to the nozzle and the first measurement has the first location as its starting point. This means that, with the first distance known, the distance between the nozzle and the physical outside surface may be derived. 
         [0014]    The first location and the nozzle may define a fixed first separation between them. Alternatively, the first location and the nozzle may define a variable first separation between them, e.g. by sliding the nozzle along a rail while maintaining the first location fixed. 
         [0015]    The first evaluation of the first distance according the first aspect of the present invention may involve a direct application of the first distance to an evaluation algorithm. The evaluation algorithm may for example subtract the first distance from a reference distance to determine which of the distances that is the largest. The evaluation may also involve other parameters than the first distance and more complex functions, e.g. the first distance and the angle between the measurement direction and a vertical line may be applied to a trigonometric function to derive the vertical distance between the distance sensor and an airplane wing, where the vertical distance is evaluated in a subtraction as mentioned above. 
         [0016]    In the operational step of controlling the nozzle position and/or nozzle orientation, the term controlling is understood to encompass the changing of the nozzle position and/or nozzle orientation and the maintaining of the current nozzle position and/or nozzle orientation according to the first evaluation. 
         [0017]    The de-icing fluid according to the first aspect of the present invention may be a fluid specifically intended for removing ice or snow, or for preventing a layer of ice or snow to form. The fluid may be a liquid that is containing chemicals, such water and glycol mixtures, which are suitable for de-icing. Further, the de-icing fluid may be heated, which improves the de-icing. The fluid may also be gaseous, such as compressed air, which is primarily used to remove snow or sleet on the aircraft wing. A de-icing liquid may be applied following the application of the gaseous de-icing fluid. If applying both a gaseous de-icing fluid and a de-icing liquid, this may be performed consecutively through the same nozzle, or through two separate nozzles, either consecutively or simultaneously. 
         [0018]    The step of applying the first distance in the first evaluation may comprise the sub-steps of: providing a first reference distance, comparing the first distance and the first reference distance, and the step of controlling the position and/or the orientation of the nozzle according to the first evaluation may comprise the sub-steps of: moving the nozzle away from the physical outside surface if the first distance is smaller than the first reference distance. This enables the nozzle to be automatically kept outside a minimum distance from the physical outside surface of the aircraft, where the minimum distance is defined by the first reference distance. This way, with a constant flow of de-icing fluid, the amount of de-icing fluid per unit area and unit time that is applied on the physical outside surface may be limited to prevent an unnecessary consumption of de-icing fluid. Further, the minimum distance may also prevent the nozzle from colliding with the physical outside surface, which is a particular advantage if the nozzle is manually operated to sweep over and across the physical outside surface. As the operator does not have to consider the danger of collisions during de-icing, the operator can instead fully concentrate on the actual de-icing. 
         [0019]    The step of applying the first distance in the first evaluation may comprise the sub-steps of: providing a second reference distance, comparing the first distance and the second reference distance, and the step of controlling the position and/or the orientation of the nozzle according to the first evaluation may comprise the sub-steps of: moving the nozzle towards the physical outside surface if the first distance is larger than the second reference distance. This enables the nozzle to be automatically kept inside a maximum distance from the physical outside surface of the aircraft, where the maximum distance is defined by the second reference distance. This ensures that, with a constant flow of de-icing fluid, a certain minimum amount of de-icing fluid per unit area and unit time that is applied on the physical outside surface is reached. 
         [0020]    The first reference distance and the second reference distance may be the same, or approximately the same, which means that in controlling the position of the nozzle, the position of the nozzle will be adjusted continuously so that the nozzle may define an approximately constant distance to the physical outside surface. 
         [0021]    The step of controlling the position and/or the orientation of the nozzle according to the first evaluation may further comprise the sub-step of: changing the position and/or the orientation of the nozzle according to the first evaluation. 
         [0022]    In the method according to the first aspect of the present invention the measurement direction may be vertical. When applying a de-icing fluid to the aircraft wing, the ice or snow is generally forced in a direction roughly parallel to the upper surface of the aircraft wing. The upper surface in turn defines a normal that, for most of its area, is roughly vertical. Hence, most of the ice will move in a direction perpendicular to the measurement direction, thus causing less noise or disturbances in the distance measurement. 
         [0023]    The physical outside surface may be an aircraft wing and the method may further comprise the steps of: providing a detection of a physical edge of the aircraft wing, the detection being along a detection direction from a second location, the second location and the nozzle defining a second separation between them, applying the detection in a second evaluation, and controlling the position and/or the orientation of the nozzle according to the second evaluation. Here, the physical edge may be the leading edge or the trailing edge of the aircraft wing. The detection of a physical edge has the advantage that the de-icing may be adapted and optimized with respect to the relative location of the edge. The method according to the first aspect of the present invention may further comprise the step of: applying the first distance in the second evaluation. This has the advantage that an evaluation can be performed taking the detection of the edge and the distance into account simultaneously. For example, the distance to the edge may be determined. 
         [0024]    The detection may be the result of a large increase of the first distance when the measurement direction falls outside the aircraft wing, i.e. when it no longer point at its upper surface. If the measurement is short ranged, the detection of the edge may correspond to the loss of a reflection signal, e.g. an ultrasonic reflection signal, when the measurement direction falls outside of the aircraft wing; or conversely, the appearance of a reflection signal when the measurement direction falls upon the aircraft wing. The detection direction may be defined as the intended direction of measurement of the sensor employed. Further, the detection direction may be determined as the direction of an emitted detection signal, or the direction of an reflected signal, or an combination of both. 
         [0025]    The first location and the second location may be the same. Additionally or alternatively, the measurement direction and the detection direction may be co-linear. This has the advantage that the location of a point or a section of the edge can readily be determined. 
         [0026]    The method according to the first aspect of the present invention may further comprise the step of: positioning the nozzle above the aircraft wing. This step may be the first step of a de-icing operation. Further, it may be performed manually by an operator. 
         [0027]    The step of controlling the position and/or the orientation of the nozzle according to the first evaluation and/or the step of controlling the position and/or the orientation of the nozzle according to the second evaluation may further comprise the sub-step of: moving the nozzle along a first path above the aircraft wing. 
         [0028]    Here, moving along a first path may mean a movement over a part of or the complete length of a fluid application path. This feature allows for an automated movement of the nozzle with respect to an aircraft wing, which enables an optimization of de-icing with respect to the amount of de-icing fluid used or the time needed for de-icing. Here, moved along the fluid application path means that the nozzle traces along the fluid application path. 
         [0029]    Further, the fluid application path may correspond to any continuous curve in two-, or three-dimensions, for example a straight line, a circle, or a helix. Knowing the fluid application path, this feature has the advantage that the amount of de-icing fluid applied to a whole wing can be estimated or calculated beforehand, which in turn means that the de-icing can be optimized with respect to de-icing time and de-icing fluid consumption. The flow rate of the de-icing fluid may depend on the position along the fluid application path. 
         [0030]    The fluid application path may be circular arc, which has the advantage that, with an extendable support arm at its maximum extension, it allows for a maximum reach or area coverage for the nozzle. 
         [0031]    The fluid application path may define a fixed horizontal distance to the bisector defined by the leading and the trailing edges. This feature has the advantage that the de-icing may be concentrated at the centre of an aircraft wing. Further, several operators may work together to de-ice an aircraft wing, where each operator has been given a unique fixed horizontal distance, such that they in unison cover the whole upper surface with de-icing fluid. This way the de-icing can be completed more quickly. Here, the fixed horizontal distance corresponds to a substantially constant horizontal distance component, which may be zero, i.e. the fluid application path follows a path directly above the bisector. Two previously measured sets of data may be employed for determining the bisector of an aircraft wing, the first set corresponding to a position of a point on the leading edge, and the second set corresponding to a position of a point on the trailing edge, where the bisector is determined as the middle point on a straight line between these two points. Alternatively, the bisector may be determined as the middle point of the shortest path tracing the upper convex surface of an aircraft wing, and that goes between a point on the first edge and a point on the second edge. 
         [0032]    The fluid application path may define a series of single-loops when projected onto a horizontal plane and each single loop of the series of single loops crosses itself once. Here, a single-lop may correspond to a smooth curve without sharp turns, to a polygon, or to a curve having both sharp and smooth turns. The single-loops may be such that they are parallel to a part of the first edge or the second edge. This way, the de-icing may be more concentrated to the edge in question. 
         [0033]    The step of applying the first distance in a first evaluation and/or the step of applying the detection in a second evaluation may further comprise the sub-step of: determining the location of a first start point and the location of a first end point relative to the physical edge of the aircraft wing for the first path. 
         [0034]    Several operators may work together to de-ice an aircraft wing, where each operator has been given a unique first start point and a unique first end point, such that they in unison cover the whole upper surface with de-icing fluid by tracing their respective first paths. This way the de-icing can be completed more quickly. 
         [0035]    The first start point may be closer to the trailing edge than the first end point and the first end point may be closer to the leading edge than the first start point. This has the effect that the first path to some extent transverses the aircraft wing. 
         [0036]    The step of applying the first distance in a first evaluation and/or the step of applying the detection in a second evaluation may further comprise the sub-step of: determining the location of a second start point and the location of a second end point relative to the physical edge of the aircraft wing, the second start point being closer to the leading edge than the second end point and the second end point being closer to the trailing edge than the second start point, and the step of controlling the position and/or the orientation of the nozzle according to the first evaluation and/or the step of controlling the position and/or the orientation of the nozzle according to the second evaluation may further comprise the sub-step of: moving the nozzle along a second path from the second start point to the second end point. This has the effect that the second path to some extent transverses the aircraft wing. 
         [0037]    The first end point of the first path and the second start point of the second path may have the same location and join the first path and the second path, or the second end point of the second path and the first start point of the first path may have the same location and join the second path and the first path. This has the effect that the combined first and second paths enable a automated and repeated crossing of the nozzle above the wing, e.g. in a zigzag pattern. 
         [0038]    The step of applying the first distance in a first evaluation and/or the step of applying the detection in a second evaluation may further comprise the sub-step of: determining the location of a third start point and the location of a third end point, the third start point and the third end point having approximately the same distance to the leading edge or the trailing edge of the aircraft wing, the step of controlling the position and/or the orientation of the nozzle according to the first evaluation and/or the step of controlling the position and/or the orientation of the nozzle according to the second evaluation may further comprise the sub-step of: moving the nozzle along a third path from the third start point to the third end point. This has the effect that the nozzle to some extent moves along the wing, either from the tip of the wing towards the fuselage, or from the fuselage towards the tip of the wing. 
         [0039]    The first path may be in a first vertical plane and/or the second path may be in a second vertical plane and/or the third path may be in a third vertical plane. These features have the effect that the movement of the nozzle defines one or more straight lines when projected onto a horizontal surface. This has the advantage that the position of the nozzle can be adjusted dynamically according to the first distance or the detection of the physical edge, even though sideway movements are not allowed. 
         [0040]    Further, the first vertical plane and the second vertical plane may be parallel. This enables the nozzle to quickly cross the wing back and forth, e.g. in a square pattern. The third path may define an approximately constant distance to the leading edge or the trailing edge of the aircraft wing. 
         [0041]    The first end point of the first path and the third start point of the third path may have the same location and joining the first path and the third path, or the second end point of the second path and the third start point of the third path may have the same location and joining the second path and the third path. Further, the third end point of the third path and the second start point of the second path may have the same location and joining the third path and the second path, or the third end point of the third path and the first start point of the first path may have the same location and joining the third path and the first path. This enables the wing to quickly move along the wing. It also enables the nozzle to move in a square or trapezoid pattern. 
         [0042]    The step of controlling the position and/or the orientation of the nozzle according to the second evaluation may further comprise the sub-step of: providing a minimum horizontal displacement between the nozzle and the edge of the aircraft wing. This has the advantage that the nozzle, when it is moving atop of the wing, it will not cross the edge. Further, with the minimal horizontal displacement can be chosen so that the loss of the amount of de-icing missing the wing is lowered. 
         [0043]    The first path and/or the second path and/or the third path may be a linear segment of a zigzag pattern of a fluid application path for the nozzle. If the zigzag pattern generally defines a movement component in the direction of the tip of the aircraft wing, e.g. by repeatedly crossing the bisector of the wing, this feature allows for a fast sweep with the nozzle over the aircraft wing. This may be favourable for removing thin layers of ice or snow, e.g. frost, where only a small amount of de-icing liquid per unit area is needed. 
         [0044]    The first path and/or the second path and/or the third path may be a linear segment of a square or trapezium pattern of a fluid application path for the nozzle. This may be favourable for removing thicker layers of ice or snow, since the path length for these patterns is generally longer than that of zigzag patterns, which allows for a larger amount of de-icing liquid per unit area to be deployed. 
         [0045]    The objects, advantages and features are according to a second aspect of the present invention obtained by a method for at least partially de-icing an aircraft wing by applying a de-icing fluid through a nozzle, the method comprising the steps of: providing a detection along a detection direction of a physical edge of the aircraft wing, applying the detection in a second evaluation, controlling the position and/or the orientation of the nozzle according to the second evaluation, and applying the de-icing fluid to at least a part of the aircraft wing trough the nozzle. Here, the physical edge may be the leading edge or the trailing edge of the aircraft wing. The detection of a physical edge has the advantage that the de-icing may be adapted and optimized with respect to the relative location of the edge. 
         [0046]    The detection may be the result of a large increase of the first distance when the detection direction falls outside the aircraft wing, i.e. when it no longer point at its upper surface. If the measurement is short ranged, the detection of the edge may correspond to the loss of a reflection signal, e.g. an ultrasonic reflection signal, when the measurement direction falls outside of the aircraft wing; or conversely, the appearance of a reflection signal when the measurement direction falls upon the aircraft wing. 
         [0047]    In the method according to the first and the second aspects of the present invention, the step of controlling the position and/or the orientation of the nozzle according to the second evaluation may further comprise the sub-step of: changing the position and/or the orientation of the nozzle according to the second evaluation. The changing of the position and/or orientation enables an automated de-icing that takes the relative position of the edge into account. 
         [0048]    In the method according to the first and the second aspects of the present invention, the step of controlling the position and/or the orientation of the nozzle according to the second evaluation may further comprise the sub-step of: discontinuing a change in the position and/or the orientation of the nozzle according to the second evaluation. This allows for the de-icing to be automatically interrupted when the nozzle reaches an edge of aircraft wing, thereby preventing automated movement outside of the upper surface of the aircraft wing. This may also have the advantage that less de-icing fluid will miss the upper surface of the aircraft wing. 
         [0049]    The method according to the first and the second aspects of the present invention may further comprise the step of terminating the application of the de-icing fluid according to the second evaluation. This feature has the advantage that the amount of de-icing fluid that misses the aircraft wing may be reduced, or for that matter, the time for de-icing an aircraft wing is shortened. 
         [0050]    The objects, advantages and features are according to a third aspect of the present invention obtained by a system for at least partially de-icing a physical outside surface of an aircraft by applying a de-icing fluid, the system comprising: a nozzle for applying a de-icing-fluid to the physical outside surface, a first sensor for measuring a distance to the physical outside surface of the aircraft and/or for performing a first detection of a physical edge of an aircraft wing, evaluation means for applying the distance and/or the first detection in one or more evaluations, and control means for changing the position and/or the orientation of the nozzle according to the one or more evaluations. 
         [0051]    The first sensor may be a direct reflection sensor, e.g. ultrasonic, infrared LED, laser diode, and radar range finders; or a triangulation sensor, e.g. an infrared LED, laser diode triangulation range finder. The first sensor may be a single unit comprising both emitter and sensor in a common housing, or a dual unit comprising emitter and sensor in separate housings, where the latter is more common in connection with triangulation sensors. Preferably, the first sensor is an ultrasonic direct reflection range finder. The first sensor may be a two-dimensional scanner, e.g. a rotating or swivelling time-of-flight laser range finder, or a laser triangulation sensor with the laser and/or the sensor having an adjustable position and/or orientation. 
         [0052]    The evaluation means according to the third aspect of the present application may further comprise an evaluation circuit. The evaluation circuit may be in communication with the first distance sensor by a connection, and a signal corresponding to the distance may be sent from the distance sensor through the connection to the evaluation circuit. The evaluation circuit may be a purely analogue circuit, or it may involve digital components. 
         [0053]    The evaluation means may be in communication with the control means to provide it with control signals according to the one or more evaluations. The control signal may be an audio signal and/or a visual signal transmitted to an operator, e.g. a warning signal that the nozzle is closer than a certain distance to an aircraft wing may be transmitted via a loud speaker, a lamp, and/or a display. The control signal may comprise data corresponding to data from the first sensor that is displayed to an operator, e.g. the measured distance that is displayed on a LCD. 
         [0054]    The control means according to the third aspect of the present application may further involve a control circuit for controlling of the nozzle position and/or nozzle orientation. The control means may be provided with instruction for an automated control system to change the nozzle position and/or the nozzle orientation. Further, the control means may also be provided with instruction for maintain the current nozzle position and/or the nozzle orientation. Further, the control means may involve an automated control system, which means that the de-icing can readily be performed under bad visual conditions, making the de-icing less dependent on commands from an operator. The control means may comprise a pneumatic, hydraulic, and/or electric system to affect mechanical motion and change the position and/or orientation of the nozzle. 
         [0055]    The control means may comprise: a first pivot support for supporting the nozzle and for changing the orientation of the nozzle. In the controlling of the nozzle orientation the fluid application direction may be changed by a pivoting of the nozzle by the first pivot support, where the pivoting defines an angular velocity. This enables the de-icing fluid that is projected onto the aircraft wing to force the snow or ice to be swept in the direction corresponding to the change in the fluid application direction. The angular velocity may be constant or variable. Additionally or alternatively, the angular velocity may be function of the measurement direction and/or the orientation of the nozzle. At a fixed nozzle position, a rotation of the nozzle will change the distance travelled by the de-icing fluid between the nozzle and the aircraft wing. In a rough model, the upper surface of the aircraft wing corresponds to a horizontal surface. If the nozzle is positioned directly above the aircraft wing, the distance travelled by the de-icing fluid increases with an increased tilting angle between the fluid application direction and a vertical axis. Under these conditions, in order to supply an even layer of de-icing fluid to the aircraft wing, the rotation velocity must decrease with an increased tilting angle. 
         [0056]    The control means may further comprises: a support arm having a first proximal end and a first distal end, the first pivot support being connected to the support arm at the first distal end. Further, the support arm may be extendable for changing the position of the nozzle, which means that it may vary its length. The control means may further comprise: a second pivot support for supporting the support arm at the first proximal end of the support arm for changing the position and orientation of the nozzle. Additionally or alternatively, the control means may further comprise: a boom having a second proximal end and a second distal end, the second pivot support being connected to the boom at the second distal end. The boom may be articulated for changing the position and orientation of the nozzle. Alternatively or additionally, the boom may be extendable for changing the position of the nozzle. The control means may further comprise: a third pivot support for supporting the boom at the second proximal end of the boom for changing the position and orientation of the nozzle. Additionally or alternatively, the control means may further comprise: a land vehicle supporting the boom via the third pivot support for changing the position and orientation of the nozzle relative to the surroundings. The land vehicle may further comprise: a source of the de-icing fluid, and a pump system to provide a pressurized flow of the de-icing fluid from the source of the de-icing fluid to the nozzle. 
         [0057]    The de-icing fluid may be a mixture of ethylene glycol or propylene glycol and water, or a mixture of ethylene glycol, propylene glycol, and water. Alternatively, the de-icing fluid may be air. The land vehicle may further comprise: a heater for heating the de-icing fluid. 
         [0058]    In the system according to the third aspect of the present invention, the first sensor may comprise a rotating sensor scanning in a plane. This has the advantage that the same rotating sensor can both measure the distance to the physical outside surface of an aircraft and perform a detection of the physical edge of the same aircraft wing. The rotating sensor may be oriented to scan in a vertical plane. Further, the rotating sensor may be a rotating time-of-flight laser range finder. 
         [0059]    In the system according to the third aspect of the present invention, the first sensor may be supported by a first sensor support at the first distal end of the support arm. The first sensor may be rigidly connected to the nozzle, which means that they move as a single unit if rotated or transiationally repositioned. When employing the distance sensor in a measurement, this means that disturbances caused by the de-icing fluid when it travels from the nozzle to aircraft wing, to a certain degree, may be compensate for, as volume and flow of expelled de-icing fluid between the nozzle and wing is roughly constant. Rigidly connected may mean that the distance sensor is directly supported by the nozzle, or supported by the same support as the nozzle. Additionally or alternatively, the fluid application direction defined by the nozzle may be parallel to the measurement direction, which may have the advantage that the first distance roughly corresponds to the general distance travelled by the de-icing fluid. Knowing this distance means that it is possible to determine the de-icing effect for a given flow and temperature of the de-icing fluid. Conversely, aiming for a certain de-icing effect and knowing the flow and temperature of the de-icing fluid, this effect may be realised at a certain distance travelled by the de-icing fluid, where this distance now is readily determined. 
         [0060]    The first sensor support may be a pivot support for actively changing the sensing direction of the first sensor. By actively changing is meant that the orientation to some extent is actively controlled by the system. Additionally or alternatively, the first sensor support may be a pendulum support for passively providing a vertical sensing direction of the first sensor. This may be achieved by the pendulum support allowing the distance sensor to swing like a pendulum by the force of gravity, which means that the distance sensor is biased towards a certain orientation under normal operation conditions. When applying a de-icing fluid to the aircraft wing, the ice or snow is generally forced in a direction roughly parallel to the upper surface of the aircraft wing. The upper surface in turn defines a normal that, for most of its area, is roughly vertical. Hence, most of the ice will move in a direction perpendicular to the measurement direction, thus causing less noise or disturbances in the distance measurement. Further, the first sensor support may be attached to the nozzle or to the support arm 
         [0061]    The system according to the third aspect of the present invention may further comprising: a second sensor for performing a second detection of a physical edge of an aircraft wing, the second sensor being supported by a second sensor support at the first distal end of the support arm. The second sensor support may be a pivot support for actively changing the sensing direction of the second sensor. By actively changing is meant that the orientation to some extent is actively controlled by the system. Additionally or alternatively, the second sensor support is a pendulum support for passively providing a vertical sensing direction of the second sensor. Further, the second sensor support may be attached to the nozzle or to the support arm. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0062]    The present invention is further revealed in the following detailed description, claims, and drawings. Additional objects, advantages and features may be apparent from the detailed description and the drawings, where: 
           [0063]      FIG. 1  illustrates a system for de-icing of aircraft wings, 
           [0064]      FIG. 2   a  is a side view of an extendable support arm having a nozzle and a sensor attached to its distal end, where the sensor is rigidly connected to the nozzle, 
           [0065]      FIG. 2   b  is a side view of an extendable support arm having a nozzle and a sensor attached to its distal end, where the sensor is pivotally connected to the nozzle, 
           [0066]      FIG. 2   c is a side view of an extendable support arm having a nozzle and a sensor attached to its distal end, where the sensor is held in position by a pendulum support, 
           [0067]      FIG. 3  is a side view of an extendable support arm having a nozzle and a sensor attached to its distal end, where the sensor is rigidly connected to the nozzle and the sensor is a rotating sensor scanning in a vertical plane to detect the surface of a an aircraft wing and the distance thereto, 
           [0068]      FIG. 4  is a side view of an extendable support arm having a nozzle and two sensors supported at its distal end, 
           [0069]      FIG. 5  is a flow chart illustrating an automated method for de-icing an aircraft wing, 
           [0070]      FIG. 6  illustrates a fluid application path defining a fixed horizontal distance to the leading edge of an aircraft wing, 
           [0071]      FIG. 7  illustrates a fluid application path defining a fixed horizontal distance to the trailing edge of an aircraft wing, 
           [0072]      FIG. 8  illustrates a fluid application path defining a fixed horizontal distance to the bisector of an aircraft wing, 
           [0073]      FIG. 9  illustrates a fluid application path defining a series of single-loops having smooth turns, 
           [0074]      FIG. 10  illustrates a fluid application path defining a series of single-loops having sharp turns, 
           [0075]      FIG. 11  illustrates a fluid application path defining a zigzag pattern along an aircraft wing, 
           [0076]      FIG. 12  illustrates a fluid application path defining a zigzag pattern across an aircraft wing, 
           [0077]      FIG. 13  illustrates a fluid application path defining a square pattern along an aircraft wing. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0078]    A preferred embodiment of the proposed system for de-icing is illustrated in  FIG. 1.The  nozzle  10  for supplying a de-icing liquid is supported by a first pivot support that is attached to an extendable support arm  15 . The first pivot support  12  provides an adjustable orientation of the nozzle  10  by a horizontal pivot axis allowing a pivotal motion in a vertical plane embedding the adjustable support arm  15 , and a normal pivot axis allowing sideways motions with respect to the extendable support arm  15 . The first pivot support  12  is also provided with actuation mechanisms enabling an automated pivotal motion of the nozzle  10 . The nozzle is supplied with de-icing liquid via conduits  14 . The support arm is provided with conduit supports  16  for preventing a slackening of the conduits  14  when the length of the extendable support arm  15  is changed. The support arm  15  is divided into three segments that can slide with respect to one another, thereby enabling a extension of the support arm  15  by a telescopic action. In  FIG. 1  the support arm is shown at its maximum extension. 
         [0079]    The support arm  15  is supported by a second support  17  attached to a boom  21 . The second pivot  17  defines a horizontal pivot axis allowing a pivotal motion in a vertical plane and a vertical pivot axis allowing a pivotal motion in a horizontal plane. A cabin  18  is connected to the vertical pivot axis so that the turning of the cabin  18  is synchronized with the horizontal turning of the support arm  15 . The boom  21  in turn is supported by a third pivot support  22 . The third pivot  22  defines a horizontal pivot axis allowing a pivotal motion in a vertical plane. 
         [0080]    The boom  21  is provided with a parallel displacement joint  20  which is connected to the third pivot support  22  via the boom  21  itself and a parallel displacement bar  30  to define a parallelogram linkage. Thereby, the vertical pivot axis of the second pivot  17  is maintained in a vertical orientation, even though the inclination of the boom  20  is changed. 
         [0081]    The third pivot support  22  is anchored to the roof  23  of a housing  26  on a truck  29  behind the driver&#39;s cabin  28 . A hand rail  24  traces the edge of the roof  22 , which can be reached from the ground via a ladder  25  at the back of the truck  29 . The housing  26  encloses a tank for storing the de-icing liquid and a pump for supplying the nozzle  10  with pressurized de-icing fluid via the conduits  14 . The housing also encloses a heater that can optionally heat the de-icing fluid. The inside of the housing  26  can be reached via a sliding door  27 . 
         [0082]    A pair of distal contact sensors  47 , in form of freely extending rods, is mounted in a downward orientation at the distal end of the support arm  15 . If any of these contact sensor sensors come in physical contact with another object, all movements of the support arm  15  and the boom  21  will terminate, which will reduce the risk for collisions with the aircraft while de-icing. 
         [0083]    A preferred embodiment of the distal end of the support arm of the de-icing system is illustrated in  FIG. 2   a . A first pivot support  12  is attached to the distal end of the distal telescopic segment  31  of the extendable support arm  15 . The first pivot support  12  supports a nozzle  10  through which a de-icing liquid can be expelled under pressure. The orientation of the nozzle  10  can be changed by pivoting it around a horizontal pivot axis  32 , allowing a pivotal motion in a vertical plane, and a normal pivot axis  33  allowing sideways motions with respect to the extendable support arm  15 . A distance sensor  11  in the form of an ultrasonic range finder is rigidly mounted onto the nozzle  10  by a fixed attachment  34 . In alternative embodiments the distance sensor  11  can be a laser, radar, or infrared rangefinder. The measurement direction  35  of the distance sensor  11  points in the general direction  36  of the expelled liquid  37 . The position of the distance sensor  11  relative to the nozzle  10  is such that, under normal operation conditions, the distance measurements are through the expelled de-icing liquid. 
         [0084]    The distance sensor  11  also doubles as a detector for detecting the edges of an aircraft wing  38  by reacting to rapid changes in the distances measured or the loss of a reflexion signal. For example, the distance sensor  11  typically measures a distance in the range of 0.5 to 2 metres to the upper surface  39  of the aircraft wing. If the distance sensor instead would point at the ground, the distance measured would at least be larger than 2.5 metres. The rapid change from a measured distance in the range of 0.5 to 2 metres to a measured distance larger than 2.5 metres then correspond to a detection of the leading edge  40  or the trailing edge  41 . 
         [0085]    An alternative embodiment of the distal end of the support arm of the de-icing system is illustrated in  FIG. 2   b . All features that are common to this embodiment and the previously described embodiments have been given the same index numbers. In this alternative embodiment, the sensor  11  is connected to the nozzle  10  via a pivotal support  42 , allowing the sensor  11  to sweep independently from the nozzle, both in a vertical plane and sideways with respect to the nozzle. 
         [0086]    Another alternative embodiment of the distal end of the support arm of the de-icing system is illustrated in  FIG. 2   c . All features that are common to this embodiment and to the previously described embodiments have been given the same index numbers. In this alternative embodiment the sensor  11  is connected to the part of the first pivot support  12  that is fixed relative to the distal segment  31  of the telescopic support arm  15 . The connection is achieved via a pendulum sensor support  43  and orients the sensor  11  so that its measurements direction  35  of the sensor  11  is held essentially vertical by the force of gravity. 
         [0087]    Yet another alternative embodiment of the distal end of the support arm of the de-icing system is illustrated in  FIG. 3 . All features in common with the previously described embodiments have been given the same index numbers. In this alternative embodiment, the sensor  11  is connected to the nozzle  10  via a fixed attachment  34 , where the distance sensor  11  is a rotating sensor that scans in a vertical plane to detect the surface of the aircraft wing and the distance thereto. By the mounting  49  the rotating sensor  11  is fixed to the fixed pivot support  12 , whereby the rotating sensor  11  follows the support arm  15 . 
         [0088]    Yet another alternative embodiment of the distal end of the support arm of the de-icing system is illustrated in  FIG. 4 . All features that are common to this embodiment and the previously described embodiments have been given the same index numbers. In this alternative embodiment, the sensor  11  is connected to the nozzle  10  via a fixed attachment  34 . An additional sensor  44  is connected to the nozzle  10  via an additional fixed attachment  45 . The sensor  11  is oriented so that, at typical operation conditions, its line of measuring does not point towards the expelled de-icing liquid  37 . Similarly, the additional sensor  11  is oriented so that, at typical operation conditions, its line of measuring  46  does not cross the expelled de-icing liquid  37 . The placement of the two sensors is such that the two lines-of-measuring are on opposite sides of the expelled de-icing fluid  37 . By this, if the sensors are used to detect the edges of the aircraft wing in a vertical sweep by the nozzle  10 , the projected de-icing liquid will not cross the edge before detection of the same. Hence, the amount of de-icing liquid lost outside the upper surface  39  of the wing  38  is significantly reduced. 
         [0089]    A preferred embodiment of the proposed method for de-icing is illustrated in  FIG. 5  as a flow-chart  59 . Initially, the extendable support arm is manually controlled so that the distance sensor and the nozzle are positioned directly above an aircraft wing. A preferred vertical distance between the distance sensor and the aircraft wing is defined in the step of defining parameters  60 . The preferred vertical distance in question has the value R 0 . 
         [0090]    In the step of defining a fluid application path  61 , a horizontal plane having the Cartesian coordinates (x,y) is first defined, in which the fluid application path is embedded. The fluid application path is defined as changes in the x and y coordinates, where each change in the x coordinate is represented by the incremental step dx i , and each change in the y coordinate is represented by the incremental step dy i . Here, the subscript i correspond to the order in which the incremental steps are performed. This way, the polygonal fluid application path in the horizontal plane is non-localised and completely defined by the two sets dx and dy having the same integer number n of elements. The two sets can be written as: 
         [0000]      dx={dx 1 , dx 2 , . . . , dx n-1 , dx n }and dy={dy 1 , dy 2 , . . . , dy n-1 , dy n }. 
         [0091]    Here, dx i  and dy i  are real-valued, i.e. they can be positive, zero, or negative. If (x 0 ,y 0 ) are defined as the starting coordinates, the localized fluid application path can then be described by a sequence of the coordinates: 
         [0000]    
       
         
           
             
               ( 
               
                 
                   x 
                   j 
                 
                 , 
                 
                   y 
                   j 
                 
               
               ) 
             
             = 
             
               ( 
               
                 
                   
                     x 
                     0 
                   
                   + 
                   
                     
                       ∑ 
                       
                         i 
                         = 
                         1 
                       
                       j 
                     
                      
                     
                       dx 
                       j 
                     
                   
                 
                 , 
                 
                   
                     y 
                     0 
                   
                   + 
                   
                     
                       ∑ 
                       
                         i 
                         = 
                         1 
                       
                       j 
                     
                      
                     
                       dy 
                       j 
                     
                   
                 
               
               ) 
             
           
         
       
     
         [0092]    In addition to the fluid application path, a vertical line having the coordinate z is defined. Naturally, the vertical line is normal to the horizontal surface embedding the fluid application path. Further, an incremental step dz is defined along the vertical line, where the step has the absolute value |dz|. 
         [0093]    A de-icing fluid is applied to the aircraft wing in the step of applying a de-icing fluid  62 . This step  62  is performed continuously during all of the following steps, which is illustrated in  FIG. 5  by placing all the following steps inside the step of applying a de-icing fluid  62 . This means that the de-icing fluid is applied continuously to the aircraft wing during operation. 
         [0094]    In the step of measuring  63 , an integer counter q, which has the initial value of 0, is first increased by one, whereupon the first distance to the aircraft wing is measured along a vertical measurement direction, giving the measured distance value P q . In the following step of evaluating  64  the preferred distance value R 0  is recalled  75  and subtracted  76  from the measured distance value P q . 
         [0095]    From the result of the subtraction  76  it is determined whether P q  is smaller than R 0    77 , is equal to R 0    78 , or P q  is larger than R 0    79 . 
         [0096]    In the subsequent step of deriving a control signal  65 , the incremental steps dx q  and dy q  are recalled from dx and dy  83 , respectively, where q correspond to q&#39;th element of the sets. The incremental step dz q  is set to +|dz| if P q  is smaller than R 0    80 , to 0 if P q  is equal to R 0    81 , or to −|dz| if P q  is larger than R 0    82 . The combined incremental steps (dx q ,dy q ,dz q ) correspond to a single step in three-dimensions, which is subsequently inserted into a function f translating it into machine instructions S  85 . The machine instructions S are sent as a control signal  70  to an automated control system. In the subsequent step of controlling  66  the automated control system carries out the instructions and moves the nozzle according to the combined incremental steps (dx q ,dy q ,dz q ). In the subsequent step of repeating  67 , the operation returns  72  to the step of measuring  63 , from which the described process is repeated again, but with the integer counter q increased by one. For the sake of clarity, in  FIG. 5  the connection  73  has been indexed to stress that R 0  is defined in the step of defining parameters  60 , while the connection  74  has been indexed to stress that dx q  and dy q  are defined in the step of defining a fluid application path  61 . 
         [0097]    In  FIG. 6  an aircraft wing  110  having a leading edge  112  and a trailing edge  113  is illustrated. The wing  110  is connected to the fuselage  111  of the aircraft. A fluid application path  121  defining a fixed horizontal distance to the leading edge of an aircraft wing has been outlined. In a preferred embodiment, the fluid application path  121  is achieved by detecting at least two points on the leading edge  112 . These points are used to define a horizontal straight line for the case of two points, or polygon in a horizontal plane for the case of more points. The fluid application path is then defined by parallel transporting the straight line or polygon in a horizontal direction so that all the points shift the same horizontal distance. Here, the horizontal shift corresponds to the fixed horizontal distance. In  FIG. 7  a fluid application path  122  defining a fixed horizontal distance to the trailing edge  113  of an aircraft wing  110  is illustrated, which instead is achieved by detecting at least two points on the trailing edge  113 . 
         [0098]    A fluid application path  124  defining a fixed horizontal distance to the bisector  123  of an aircraft wing  110  is illustrated. The bisector  123  is determined by detecting the horizontal position of at least two equidistant points on the leading edge  112  in a first series, and the same number of equidistant points on the trailing edge  113  in a second series. The distance between the points in the first series is the same as between the points in the second series. The points on each edge are ordered according to their distance to the fuselage. Points of the same order in the two series are paired together, where each pair define a line. The bisector  123  is then defined as the polygon through the middle points of these lines. The fluid application path  124  is then defined by a parallel transport of the bisector  123  in the preferred horizontal direction. 
         [0099]      FIG. 9  and  FIG. 10  illustrate fluid application paths defining a series of single-loops having smooth turns  126  and sharp turns  127 , respectively. In a preferred embodiment, the fluid application paths are initially non-localized and have no pre-defined orientations with respect to the aircraft wing  110 . The placing and orientation are manually defined by an operator by setting two coordinates corresponding to the start point  128  and end point  129  of the fluid application path. 
         [0100]      FIG. 11  illustrates a fluid application path  134  defining a zigzag pattern along an aircraft wing  110 . In a preferred embodiment, this is achieved by defining a first line  139  and a second line  140  in a horizontal plane. The lines are non-parallel, initially non-localized, and have no pre-defined orientation with respect to the aircraft wing, but have a fixed orientation with respect to one another. An operator defines the start point  135  and the direction for the first line  139 , while the end point  136  is determined by detecting the first edge, which in this example is the leading edge  112 . The end point  136  is located at a certain distance from the first edge and is subsequently defined as the start point  136  for the second line  140 . The direction of the second line  140  is already determined by its predefined relative orientation with respect to the first line  139 . The end point  137  of the second line  140  is determined by detecting the second edge, which in this example is the trailing edge  113 . The end point  137  is located at a certain distance from the second edge and is subsequently defined as the start point  137  for another line, thereby allowing the fluid application path to be extended in zigzag pattern following a recursive sequence involving the described steps of a detecting edges and defining start and end points. 
         [0101]      FIG. 12  illustrates a fluid application path  141  defining a zigzag pattern across an aircraft wing  110 . In a preferred embodiment this is achieved by combining the methods described in connection with  FIG. 6  and  FIG. 7 , i.e. by defining a first line  142  being parallel to the leading edge  112  and a second line  143  being parallel to the trailing edge  113 . The first turn point  144  and the one or more intermediary turn points  145  of the zigzag pattern are predefined by an operator; while the last turn point  146  is defined by detecting the edge, which in this example is the trailing edge  113 . The last turn point is located at a certain distance from the edge. 
         [0102]      FIG. 13  illustrates a fluid application path  147  defining a square pattern along an aircraft wing. In a preferred embodiment, this is achieved by defining a first line  148  at a first fixed distance from the edge and a second line  149  at a second fixed distance form the edge. In this example, the edge is the leading edge  112  and the first distance is smaller than the second distance. The fixed distances are obtained by a method similar to that discussed in connection with  FIG. 6 . The fluid application path is then defined by connecting the paths at predefined intervals, where the connections  150  are substantially perpendicular to the edge. 
         [0103]    Item List 
         [0104]      10  nozzle 
         [0105]      11  sensor 
         [0106]      12  first pivot support 
         [0107]      14  conduits 
         [0108]      15  support arm 
         [0109]      16  conduits support 
         [0110]      17  second pivot support 
         [0111]      18  cabin 
         [0112]      19  cabin windows 
         [0113]      20  parallel displacement joint 
         [0114]      21  boom 
         [0115]      22  boom support 
         [0116]      23  roof 
         [0117]      24  hand rail 
         [0118]      25  ladder 
         [0119]      26  housing 
         [0120]      27  door 
         [0121]      28  vehicle cabin 
         [0122]      29  truck or land vehicle 
         [0123]      30  parallel displacement bar 
         [0124]      31  distal segment 
         [0125]      32  horizontal pivot axis 
         [0126]      33  normal pivot axis 
         [0127]      34  fixed attachment 
         [0128]      35  measurement direction/line-of-measurement 
         [0129]      36  general direction of expelled de-icing liquid 
         [0130]      37  expelled de-icing liquid 
         [0131]      38  aircraft wing 
         [0132]      39  upper surface 
         [0133]      40  leading edge 
         [0134]      41  trailing edge 
         [0135]      42  pivotal sensor support 
         [0136]      43  pendulum sensor support 
         [0137]      44  additional sensor 
         [0138]      45  additional fixed holder 
         [0139]      46  additional measurement direction/additional line-of-measurement 
         [0140]      47  distal contact sensor 
         [0141]      59  flowchart 
         [0142]      60  Step of defining parameters 
         [0143]      61  step of defining a fluid application path 
         [0144]      62  step of applying a de-icing fluid 
         [0145]      63  step of measuring 
         [0146]      64  step of evaluating 
         [0147]      65  step of deriving a control signal 
         [0148]      66  step of controlling 
         [0149]      67  step of repeating 
         [0150]      72  return 
         [0151]      75  R 0  is recalled 
         [0152]      76  subtraction 
         [0153]      77  smaller than R 0    
         [0154]      78  equal to R 0    
         [0155]      79  larger than R 0    
         [0156]      80  dz q  equals +|dz| 
         [0157]      81  dz q  equals 0 
         [0158]      82  dz q  equals −|dz| 
         [0159]      83  recalling dx q  and dy q    
         [0160]      85  machine instructions S 
         [0161]      110  aircraft wing 
         [0162]      111  fuselage 
         [0163]      112  leading edge 
         [0164]      113  tailing edge 
         [0165]      121  fluid application path defining a fixed horizontal distance to the leading edge 
         [0166]      122  fluid application path defining a fixed horizontal distance to the trailing edge 
         [0167]      123  bisector of an aircraft wing 
         [0168]      124  fluid application path defining a fixed horizontal distance to the bisector 
         [0169]      126  fluid application path defining a series of single-loops having smooth turns 
         [0170]      127  fluid application path defining a series of single-loops having sharp turns 
         [0171]      128  start point 
         [0172]      129  end point 
         [0173]      132  start point 
         [0174]      133  end point 
         [0175]      134  fluid application path defining a zigzag pattern along an aircraft wing 
         [0176]      135  start point 
         [0177]      136  end/start point 
         [0178]      137  end point 
         [0179]      139  first line 
         [0180]      140  second line 
         [0181]      141  application path defining a zigzag pattern across an aircraft wing 
         [0182]      142  first line 
         [0183]      143  second line 
         [0184]      144  first turn point 
         [0185]      145  one or more intermediary turn points 
         [0186]      146  last turn point 
         [0187]      147  fluid application path defining a square pattern along an aircraft wing 
         [0188]      148  first path 
         [0189]      149  second path 
         [0190]      150  connections