Method for generating connecting paths which can be used for guiding a vehicle to a predetermined target path

A method and system generate multi-dimensional coupling paths for guiding vehicles to a destination path with a path dynamic unit (13), with a feedback control (11) for a closed loop control of at least one closed loop for sending feedback data (16, 17; 105, 106, 107) to the feedback control (11). A conversion module (15) is provided at the output of the path dynamic unit (13) for calculating destination path values (5) which are fed into the feedback control (11) as input values.

FIELD OF THE INVENTION
 The invention relates to a method for generating coupling paths. The method
 is useable for guiding a vehicle to a predetermined destination path. The
 invention also relates to a path generating system for carrying out this
 method.
 DESCRIPTION OF THE RELATED ART
 In connection with the automatic path guidance of vehicles, by which the
 vehicle is automatically guided with the aid of sensors along any
 multi-dimensional destination path, the vehicle must often first be guided
 to this destination path in a preceding step. This can be achieved on the
 one hand by a manual open loop control of the vehicle from the actual
 position to the destination path with and without specified inputs, or by
 an automatic guidance to the destination path. In both cases, however, a
 coupling path is required along which the vehicle is guided from the
 actual position to the destination path without overshooting, whereby
 particularly the entry into the destination path must lie within the
 controllability range of the vehicle.
 From aviation, coupling paths are known which bring the airplane
 automatically to a rectilinear destination path or desired flight path.
 Further, path generation systems have been developed for the generation of
 coupling paths to curved destination paths. In this context the coupling
 path is generated by assembling the coupling path from geometrical path
 elements. A disadvantage of the just mentioned method is that it requires
 a relatively large computation effort, and hence a respectively large
 equipment investment, if it is to be ensured that the method can generate
 a coupling path for any starting motion direction and for any starting
 position respectively relative to the destination path. A further
 disadvantage of the state of the art is seen in that the entire coupling
 path up to the merging into the destination path, must be generated before
 the vehicle itself is in the coupling phase, since only then can it be
 ensured that the coupling path is efficient.
 SUMMARY OF THE INVENTION
 It is an object of the invention to create a method of and a system for the
 generation of efficient coupling paths that start from any starting
 position to any specified destination paths that lie within the physical
 limits of the vehicle, but are otherwise independent of the vehicle,
 whereby the computational effort, and thus, the equipment expenditure
 shall remain as low as possible. In particular, the generated coupling
 path shall be free of breaks and shall take into consideration the
 performance and load limits of the vehicle, for example, lateral
 acceleration limits.
 It is also an object of the invention to create a method and/or a path
 generation system for the generation of coupling paths by which the
 coupling paths merge with the destination paths without overshooting.
 A further object of the invention is to create a method and/or a system for
 the generation of coupling paths, in particular for any curved, one or
 multi-dimensional destination paths that are also provided with variable
 evaluation factors or parameters along their course for taking into
 consideration, for example, aspects that change with time or preferred
 coupling ranges.
 These objects have been achieved according to the invention by the
 combination of the following steps: mapping, by a path dynamic unit,
 geometric relationships of said at least one coupling path, controlling
 said path dynamic unit through a path dynamic feedback control, to thereby
 supply feedback data, also referred to as feedback values or signals, to
 said path dynamic feedback control for said controlling of said path
 dynamic unit. Destination path values or data or signals are then
 calculated by a conversion module connected to an output of the path
 dynamic unit. Further, at least a portion of the destination path values,
 data or signals is supplied as an input signal or signals to an input of
 the path dynamic feedback control.
 According to the invention there is further provided a system for
 generating at least one coupling path for guiding a vehicle to a specified
 destination path, wherein the system is characterized by a path dynamic
 unit, a feedback control for a closed loop control of said path dynamic
 unit, at least one feedback conductor for sending feedback data to said
 feedback control, a conversion module connected to an output of said path
 dynamic unit for calculating destination path values, said conversion
 module comprising an output connected to an input of said feedback control
 for feeding said destination path values as input values or signals to
 said feedback control.
 In this context, the geometrical relationships of the coupling path that
 are independent of the vehicle, are mapped or imaged onto a dynamic model.
 This model is controlled by specifying a feedback or closed loop control
 target. The feedback control target can thereby be described by an
 instruction to bring the distance of the coupling path from the
 destination path to the zero value, or by a similar instruction.
 An advantage of the invention is that the path generation is precisely
 cycled to match the cycle time or rate of the series connected path
 feedback control, so that the path generation provides the calculated
 discrete coupling path points to the path feedback control at the cycle
 time rate at which the path feedback control requires the calculated
 discrete coupling path points.
 A further advantage of the invention is that, in addition to the coupling
 path points, further signals such as the path angle of the coupling path
 or the lateral acceleration of the vehicle on the coupling path, can be
 picked up from the path generation. Such additionally picked up signals
 can also be provided to other modules or systems, for example, the closed
 loop path feedback control. A servo control effect which can facilitate
 the path feedback control, can also be achieved with these further
 signals. Thus, it is also possible to supply the coupling path to the path
 feedback control, for example, in the form of data sets that contain the
 angle of direction and velocities, rather than in the form of position
 points.
 In phases of the coupling path generation in which the path generation can
 proceed in simplified form, it is also possible to switch off
 corresponding components of the path generation without reducing the
 safety, or in other phases, depending on the requirements, to switch on
 components, since the path closed loop feedback control remains
 uninfluenced thereby.
 With the path generation system according to the invention, coupling paths
 can be generated that merge with the destination path without
 overshooting. Thus, it is particularly possible to also use the path
 generation system for the generation of coupling paths to specified or
 also generated low level flight paths for aircraft, since with this
 system, together with a corresponding path closed loop feedback control,
 it is avoided that the aircraft comes near the ground or flies too low.

DETAILED DESCRIPTION OF PREFERRED EXAMPLE EMBODIMENTS AND OF THE BEST MODE
 OF THE INVENTION
 FIG. 1 shows a path guidance system 1 with a coupling path generation
 module referred to as path generation 3 and a path feedback control or
 module 7 referred to as closed loop path feedback control 7 or simply as
 feedback control 7. The path generation 3 includes modules for performing
 at least one mode of operation with which, under boundary or limiting
 conditions that are specified with the mode of operation, at least one
 coupling path is ascertained for a destination path that is also
 specified. The path generation 3 receives initialization values 4a that
 are entered manually or from other modules as input values or signals,
 which are preferably variables of the vehicle status. If applicable, the
 path generation receives a specified mode of operation 4b, when the path
 generation includes more than one mode of operation, and the necessary
 destination-path specified or rated inputs 4c, depending on the mode of
 operation. Alternatively, these data 4a, 4b, 4c can also be supplied,
 during the processing, to the path generation 3 by another module that is
 connected to the path generation 3. The path generation 3 sends coupling
 path data 6 as output values to the feedback control 7. The path feedback
 control 7 has the function of holding the vehicle to the calculated
 coupling path, even under the influence of external disturbances that are
 acting on the vehicle. The path feedback control 7 sends in turn the
 correction variables 8 as output data to the control systems, not shown in
 the Figs., for maneuvering the vehicle along the coupling path calculated
 according to the invention.
 FIG. 2 represents the path generation 3 according to the invention. The
 path generation 3 includes a closed loop feedback control device or a path
 dynamic feedback control 11 that delivers data 12 to a path dynamic or a
 path dynamic unit 13 which in turn supplies data 14 to a device for
 calculating destination path data also referred to as conversion module
 15. The path dynamic feedback control 11 also receives feedback data 16
 from the path dynamic unit 13 and feedback data 17 from the conversion
 module 15. The path dynamic feedback control 11 also receives as input
 variables from a module outside of the path guidance system 1, if
 applicable, the modes of operation data 4b, the destination-path rated
 inputs 4c, and destination path data or values 5 from the conversion
 module 15. The path dynamic 13 receives, in addition to the data 12 coming
 from the path dynamic feedback control 11, the initialization values 4a,
 whereby the latter can be supplied at the beginning of the path generation
 process to the path dynamic feedback control 11 or also to the conversion
 module 15. The coupling path data 6 that are supplied to the path feedback
 control, can include the data 14 for the conversion module 15 and/or other
 data 14a from the path dynamic 13. The terms "data" or "values" intend to
 cover respective electrical signals.
 FIG. 3 shows a destination path 20 that runs in a horizontal plane and the
 actual position 21 of the vehicle that is determined at the beginning of
 the path generation process with the aid of a conventional sensor unit.
 The actual vehicle position 21 is at a distance 27a from the destination
 path 20. The reference number 29a designates a fixed coordinate system
 with the coordinates x, y, z to which the geometrical operands of the path
 generation 3 have reference. Based on the respective mode of operation
 selection, the path generation 3 calculates a coupling path 25 that also
 runs in the horizontal plane and merges with the destination path 20 at
 the merge point 27.
 FIG. 4 shows an example of a one-dimensional destination path 20 and of a
 coupling path 25, whereby information analogous to that shown in FIG. 3
 has been provided with the same reference numbers. The course of altitude
 shown in FIG. 4 is the destination path 20 that is known prior to the
 coupling path generation process and that is to be fed as corresponding
 data to the coupling path generation 3. An aircraft with an initial
 altitude 24 is to be guided to the destination path along the coupling
 path 25 that is to be calculated, based on the corresponding selected mode
 of operation. The initially existing altitude spacing or distance between
 the aircraft and the destination path 20 is designated by the reference
 number 27b. A coordinate system suitable for this mode of operation is
 designated by the reference number 29b.
 The initialization values or signals 4a that are particularly required for
 starting the path dynamic 13 are actual values or status values of the
 vehicle at the beginning of the path generation process. These actual
 values can include, for example, the horizontal position, the
 instantaneous altitude above ground, or a directional value, as well as a
 combination of these values, and a combination of these values with other
 values. These values are determined at the beginning of the path
 generation process by means of a conventional sensor unit, not shown, or
 are available at this time in some other way. The path dynamic 13 requires
 the initialization values or signals 4a prior to the path generation
 process, since functions performing components of the path dynamic 13,
 such as integrators, require initial values for the generation process.
 Which actual coordinates and in which form these are required by the path
 dynamic 13 depends on the mode of operation or on the embodiment of the
 path generation 3. In one embodiment of a path generation 3 for a coupling
 path 25 according to FIG. 3, the necessary initialization values or
 signals 4a of the actual position can exist in the form of the
 corresponding x, y coordinates, the velocity, and an instantaneous
 direction of travel of the vehicle in the x-y plane.
 The destination path data or values 5 that are sent from the conversion
 module 15 to the path dynamic feedback control 11, are data that describe
 the instantaneous course of that point or range of the destination path 20
 that is relevant for the respective iteration step or path generation
 cycle. Which point or range is relevant in a cycle of the path generation
 process depends on how, in a mode of operation of the path generation 3,
 the distance 27a, 27b of the actual position 21 from the destination path
 20 is defined in the respective iteration step, or from other aspects,
 such as specified inputs with reference to the possible merge point. The
 destination path data or values 5 can include the respective destination
 path coordinate, as well as its first, second, and further derivation or
 derivations with reference to the arc length in the corresponding coupling
 path range. Thus, the data can include, for example, the direction and
 curvature of the destination path 20 in this coordinate, as well as values
 or signals derived therefrom. Instead of derivations with reference to the
 arc length, these can also be derivations with reference to path tracks in
 certain coordinate planes (for example, a flight track in the x-y
 coordinate plane) or derivations in certain coordinate axes or similar
 features. Preferably, the velocity or lateral acceleration values, that
 may be variable, of the vehicle on the corresponding destination path, are
 used for producing derived values from the mentioned values. These values
 are defined along the respective section of the destination path 20, and
 extend, for example transversely to the direction of the destination path.
 The derived values may be derived from a measured or assumed velocity of
 the vehicle. Which destination path data or values 5 are supplied from the
 conversion module 15 to the path dynamic feedback control 11 depends not
 only on the selected mode of operation, but also on the range for which
 the coupling path points are calculated in the respective iteration step.
 Thus, in the normal case, in the final phase of determining the coupling
 path 25, all data of the feedbacks 16, 17 and all available destination
 path data 5, are processed in the path dynamic feedback control 11. By
 contrast, possibly during the beginning phase of determining the coupling
 path, when the vehicle is at a relatively large distance from the coupling
 path 25, only a subgroup of the total destination path data or values 5,
 such as the destination path coordinates and their first derivation, the
 destination path direction, but not their second derivation, is used by
 the path dynamic feedback control 11.
 The path dynamic 13 causes in each iteration step the calculation of the
 geometrical data 14 that are specific to the coupling path, from the data
 12 which form the input data of the path dynamic 13, for example, in the
 form of the coordinates of the coupling path point calculated in an
 iteration step. The input data 12 of the path dynamic 13 are to be defined
 depending on the type of use and the mode of operation. For example, the
 lateral or cross acceleration of the vehicle is provided for this purpose.
 The path dynamic 13 includes preferably integrators for integrating the
 data 12 into the data 14 that correspond to the respective coupling path
 coordinates to be determined. The path dynamic 13 can furthermore include
 one or more amplifier elements, signal limiting elements and still further
 components. The physical limits of the vehicle in the coupling path 25 can
 be taken into consideration by the signal limiting elements.
 In each iteration step of the path generation 3, at least one set of
 coupling path coordinates is determined, for example, in the form of three
 coupling path coordinates or the required coupling path angle and the
 coupling path velocity, or another suitable combination of variables. This
 is done preferably in a time period during which the vehicle is moving on
 the coupling path. As an alternative thereto, the coupling path could also
 be generated before the vehicle is moving on the coupling path. The latter
 can be practical when the vehicle in this time period is in a fixed
 position to the destination path, for example a spacecraft in a stationary
 position relative to a space station.
 The path dynamic feedback control 11 processes the mode of operation inputs
 4b, destination-path specific or rated inputs 4c, depending on the type of
 use initialization variables 4a, and the destination path data 5 coming
 from the conversion module 15 and the feedback data 16, 17. The
 destination-path specific or rated inputs 4c are formed preferably either
 from the rated distance to which particularly the variable zero is
 assigned, or from the destination path data belonging to the distance 27a,
 27b. The destination path data values 5 are determined by the distance to
 be defined for each mode of operation between the respective coupling path
 point and the destination path or the respective destination path point or
 the respective destination path coordinates and their derivations or the
 lateral velocity and the lateral acceleration of the vehicle on the
 destination path resulting from the assumed vehicle velocity. The feedback
 data 16 include coupling path data, particularly their direction, their
 coordinates, and the derivation of the coupling path direction, for
 example, with respect to arc length, and if applicable, further
 derivations. The feedback data 17 include data that also contain coupling
 path data and can be based additionally on destination path data, such as
 the distance 27a, 27b of the most recently generated coupling path point
 to the destination path. The path dynamic feedback control 11 can include
 a module (not shown) that ensures that only portions of these data or
 values are processed. The path dynamic feedback control 11 can furthermore
 include a preliminary control. Such a preliminary control manages only
 rated inputs as input control data, and no feedback data 16, 17, that is
 to say, no information on the coupling path data or values, and can
 particularly contain additional information about the path dynamic. The
 preliminary control data are processed or produced within the path dynamic
 feedback control 11 and are then fed to the feedback control circuit
 within the path dynamic feedback control 11 by means of a mathematical
 operation, for example, by addition.
 Based on FIG. 3, the function of the path generation 3 according to the
 invention will be described as follows:
 At the beginning of the path generation a destination path 20 is
 predetermined and the vehicle is in its actual position 21 that lies at
 any distance from the destination path and was ascertained by a sensor
 unit not shown. Depending on the distance from the destination path 20 and
 on further influence values or variables, a certain mode of operation is
 selected manually or automatically, if several modes of operation are
 provided for in the path guidance system 1. For example, with a course of
 altitude as destination path 20, the mode of operation "one-dimensional
 vertical coupling path" or a mode of operation for generating a
 two-dimensional coupling path 25 to a two-dimensional destination path 20
 is selected. The information on the mode of operation is then transmitted
 to the path generation 3 as a preliminary input.
 After selecting the mode of operation, it may be necessary to specify a
 suitable feedback control target. This target is then either generated by
 the path dynamic feedback control 11 or, based on a manual input or from a
 corresponding other module, is sent to the path dynamic feedback control
 11. For certain modes of operation, the control target is preferably the
 zero value for the distance to be reached between the coupling path 25 and
 the destination path 20 at a merge point that must still be determined.
 Alternatively, the feedback control target is determined by the
 coordinates of the destination path 20 which coordinates are determinative
 for ascertaining the distance from the actually generated coupling path
 point to the destination path 20.
 Based on the destination path 20 and the actual position 21 of the vehicle,
 the relative location of the actual position 21 of the vehicle with
 respect to the destination path 20, that is, the distance, is determined.
 In order to determine the relative location of the vehicle with respect to
 the destination path 20, the distance 27a, 27b is defined during or in the
 course of the process. The distance 27a, 27b can be defined, starting from
 the actual position 21, as the line of the shortest distance 27a to the
 destination path 25. To determine the shortest distance 27a it can be
 provided that, in each cycle, the distance that is determined is the
 distance between the coordinates of the coupling path point ascertained in
 the preceding cycle to all destination path coordinates or a group of
 destination path coordinates, whereupon the shortest distance and the
 corresponding destination path point or a subset of destination path
 points, is calculated. Another method, however, can be provided for the
 definition and determination of the instantaneous distance. For example,
 it can be practical to calculate the distance as the difference in
 altitude between the coupling path point ascertained in the preceding
 cycle and the destination path point lying vertically above it, in order
 to generate a coupling path 25 to a destination path 20 that is determined
 only in its altitude course. Other definitions of the distance 27a, 27b
 may also be practical, for example, in order to take into account ranges
 in which the coupling path 25 is not supposed to merge with the
 destination path 20. Furthermore, in the case, in which the mentioned
 shortest distance between the actual position 21 of the vehicle and the
 destination path 20 falls below a predetermined value or below a value to
 be determined in the path generation 3, another type of distance
 determination is provided. In that case the shortest distance to the
 connecting straight line of two neighboring path points or the distance to
 a curve that goes through the relevant destination path points is used as
 the distance for calculating.
 The coupling path generation must be initiated before the process begins.
 For this purpose initialization values 4a are supplied particularly to the
 path dynamic 13, or also to the feedback control device 11 or also to the
 conversion module 15. The initialization values 4a are typically vehicle
 status values and generally data or values that are suitable to initiate
 the integrators and, if applicable, further functions of the path dynamic
 13, so that a value is allocated to these functions, which value is
 relevant for the first iteration step.
 The path generation 3 generates a coupling path 25 within a specified step
 width by using the data or values of the destination path 20 and of the
 actual position 21. The step width corresponds for example to a time slot
 determined by the cycle rate of the computer for the path feedback
 control. In this context, the destination path data or values 5 provided
 initially for the respective cycle and feedback data 16, 17 are processed
 in each calculation cycle in the path dynamic feedback control 11. The
 destination path data or values 5 fed to the path dynamic feedback control
 11 are calculated in the conversion module 15, that is, are converted
 particularly into the geometry data required for the path dynamic feedback
 control. The data or values 12 determined in the path dynamic feedback
 control 11 are fed to the path dynamic 13 and are processed to form data
 or values 14 by means of the path dynamic 13. In the respective cycle the
 data or values 14 correspond to the coupling path coordinates 6 that are
 to be fed to the path feedback control 7.
 Which destination path data or values 5 from the conversion module 15 and
 which feedback data 16, 17 from the path dynamic 13 or from the conversion
 module 15 are sent to the path dynamic feedback control 11 or processed by
 this control depends, on the one hand, on the type of use, and on the
 other hand, on the range of the destination path 20 to be determined.
 According to the invention, however, depending on the demand on the path
 generation 3, derivations can be provided at least temporarily both for
 the velocity and acceleration values with the destination path data or
 values 5 and/or with the feedback data 16, 17, as well as third or further
 derivations of the destination path 20 or of the coupling path 25 formed
 with reference to time or with reference to the distance.
 Independent of whether velocity values, acceleration values, or values of
 further derivations are fed by means of the destination path data or
 values 5 or the feedback data 16, 17 to the feedback control device 11,
 the processing of the destination path data or values 5 and the processing
 of the feedback data or values 16, 17 in the feedback control device 11 do
 not always have to be active simultaneously. In a preferred embodiment of
 the invention, the processing of these data in the feedback control device
 11 is activated depending on the instantaneous progression of the coupling
 process, that is, it depends on how the coupling path 25 and the
 destination path 20 run relative to one another. In the normal case, for
 example, the processing of the destination path curvature as an element of
 the destination path data or values 5 is done only in the final phase of
 the coupling, that is, shortly before the vehicle reaches the destination
 path 20. By processing the destination path data or values 5 in the
 feedback control device 11 it can be achieved that the coupling path 25
 merges with the destination path 20 without overshooting.
 It can be provided that several types of coupling paths 25, for example, in
 addition to one-dimensional, also two- and three-dimensional coupling
 paths 25, may be generated by the path generation 3. In addition to the
 spatial dimensions, still other additional dimensions can be generated for
 the coupling paths, for example, by generating an additional variable
 velocity instead of a constant velocity. In the preferred example
 embodiment, the corresponding mode of operation is to be selected prior to
 the generation process. In this way, the destination-path rated input 4c
 that is linked with the mode of operation, can be automatically generated
 as a feedback control target or a predetermined rated path input. It can,
 however, also be provided that the feedback control target is to be
 predetermined in addition, for example, by a manual input.
 The system described for generating a coupling path 25 can in general be
 used for any vehicle that moves in space and that is to be led to a
 destination path 20. In addition to aircraft and spacecraft, terrestrial
 vehicles such as automobiles or ships can also be taken into consideration
 for this purpose.
 The arrangement of the units shown in the Figures, such as the path dynamic
 feedback control device 11, the path dynamic unit 13, or the conversion
 module 15 for calculating destination path values, represents a functional
 arrangement which is independent of in which modules of the corresponding
 computer units these units are implemented.
 According to the invention several path generations 3 can also be networked
 with another to communicate with each other either simultaneously or in a
 time sequence.
 Furthermore, the described path generation 3 can be expanded analogously
 for the generation of coupling paths with more than two dimensions. For
 example, a coupling path described by the three spatial coordinates can be
 generated. In addition, a variable velocity characteristic or time
 progression can be generated as a further dimension relative to the
 spatial dimensions.
 Referring to FIGS. 5 and 6, types of use of the path generation 3 of the
 invention will now be described, whereby components that functionally
 correspond to those described with reference to FIGS. 1 to 4 have the same
 reference numbers.
 Referring to FIG. 5 an example of use is described wherein a vertical
 coupling path 25 to an altitude course that is specified as the
 destination path 20, is generated for an aircraft. The coupling path 25
 and the specified altitude course are thus one-dimensional paths.
 In order to start the process of path generation, the path dynamic 13 the
 initiating values 4a, here concretely the altitude at the time point zero,
 and its derivation over time. The feedback control device 11 receives the
 mode of operation inputs 4b and the destination-path rated inputs 4c.
 The destination path data or values 5 that are fed by the conversion module
 15 to the feedback control device 11, are relevant for the respective
 calculation cycle. These data or values 5 can include the destination path
 position, which in this example is a corresponding altitude value 51 of an
 altitude course, the vertical velocity of the destination path or the
 direction of the destination path, for example with reference to a
 coupling path value 52, in particular the instantaneous slope value of the
 destination path, the acceleration of the destination path or the
 destination path curvature value 53 in the direction of the coupling path,
 and the change in the destination path acceleration value 54 in the
 direction of the coupling path. These data or values 5 are time or
 distance dependent. Further, depending on the mode of operation or on the
 phase of the generation process, one or more of the data or values 51, 52,
 53, 54 is/are supplied to the feedback control device 11 in a calculation
 cycle.
 Furthermore, in the use example shown in FIG. 5, the acceleration or
 curvature values 56a of the coupling path 25, the velocity values 56b of
 the coupling path 25 and the destination path altitude 57 constitute the
 feedback data 16 that are fed from the path dynamic 13 to the path dynamic
 feedback control 11. The feedback 17 shown in FIG. 2, which generally
 includes new data that are derived from the destination path and from the
 coupling path, such as the distance between the destination path and the
 coupling path, is not required in the example of FIG. 5.
 The data or values 14, calculated in each calculation cycle by the path
 dynamic 13, are formed in the use example according to FIG. 5, by the
 altitude coordinates 60 of the coupling path 25. As shown in FIG. 5, the
 altitude coordinates 60 are fed to the path feedback control 7 in each
 calculation cycle with which the aircraft is guided along the generated
 coupling path 25. On the other hand, the altitude coordinates 60 are
 passed on to the conversion module 15 that calculates the destination path
 data or values 5 or the data or values 51, 52, 53, 54, among other data,
 with the aid of the destination path geometry and the flight velocity that
 is determinative for the respective calculation cycle.
 The path dynamic feedback control 11 processes in each calculation cycle
 the respective relevant destination path position based on the altitude
 value 51 from which the respective relevant altitude 57 of the coupling
 path 25 is subtracted at that location or at a differentiating point or
 summing circuit 61. Conventional closed loop control elements may be
 provided downstream of the summing circuit 61. As shown in FIG. 5, an
 amplifier 62 is provided.
 A velocity component or value 56b of the coupling path 25 is subtracted
 from the destination path vertical velocity value 52 downstream of the
 transmission element, e.g. an amplifier 62, at a further differentiating
 point or summing circuit 64. Subsequently, the then resulting feedback
 control value or signal is processed by an amplifier 65 and, if
 applicable, by a limiter circuit and by further conventional elements not
 shown, but depending on the type of use. The destination path acceleration
 or curvature value 53 is added to the then resulting signal value by a
 summing circuit 67 and, optionally, the acceleration and/or curvature
 component or value 56a is subtracted. The then resulting feedback control
 value is processed by at least one amplifier 68 and, optionally, by a
 following limiter circuit 69. Hereafter, any change in the acceleration
 value 54 is added. The then resulting signal forms the data or values 12
 which constitute the input data for the path dynamic 13 in the use example
 according to FIG. 5.
 The described processing of the feedback data or values 56a, 56b, 57 and of
 the destination path data or values 5 or 51, 52, 53, 54 does not have to
 take place completely in each cycle. Depending on the phase of the path
 generation, only one, two or three destination path data or values 51, 52,
 53, 54, that is, a subset of the same, and also a subset, for example,
 only of the feedback values 16, 17, or 56a, 56b, 57 can be fed in a cycle
 to the feedback control 11. The signal or value 56b is picked up at a tap
 75b downstream of the signal limiter 76.
 The path dynamic 13 can include an optional acceleration filtering unit 71
 that integrates the input data or values 12 and feeds its output to a
 limiter circuit 72. With the limiter circuit 72 the acceleration limit
 values can be taken into consideration with respect to the coupling path
 25. The output signal 73 of the limiter circuit 72 is fed back to the
 feedback control device 11 as an acceleration or curvature component or
 value 56a of the coupling path 25. The output signal 73 corresponds to a
 lateral acceleration value of the coupling path 25, based on an assumed
 flight velocity or a double derivation of the coupling path 25 with
 reference to time or distance. The output signal 73 is then integrated
 within the path dynamic 13 by means of an integrator 74 and processed to
 form a signal 75 that corresponds to the first derivation of the altitude
 course of the coupling path with reference to time. A limiter circuit 76
 limits the signal 75 to form a signal 75b which is fed back to the
 feedback control 11 as a velocity component or value 56b of the coupling
 path 25. A maximal altitude climbing speed that is rated for the vehicle,
 can be taken into account in the path dynamic 13 through the signal
 limiter element 76. When the limiter 76 is in effect, the signal 75b is
 also fed through an integrator 78 as a signal 77 to the integrator 74,
 whereby the integrator 74 receives narrower limiting values. The signal
 75b at the output of the limiter 76 is integrated by the integrator 78
 with the altitude coordinates or values 60 that, on the one hand, are fed
 to the path feedback control 7, and on the other hand, to the conversion
 module 15.
 The individual function components of the feedback control 11 and the path
 dynamic 13, and the determination of their parameters, result from the
 particular use example and also from the respective processing phase. For
 example, the parameters for the amplifiers 62 and 65 result, in
 particular, from two requirements. On the one hand, the attenuation of the
 control circuit shall be one in order to avoid overshooting the coupling
 path. On the other hand, the natural frequency of the control circuit can
 be determined so that at a higher natural frequency the coupling path 25
 approaches more quickly the destination path 20. The physical limits of
 the vehicle are reflected in the non-linear signal limiters 69 and 76 that
 can be optionally provided in the feedback control 11 and in the path
 dynamic 13 respectively. The altitude coordinates 60 that are fed to the
 path feedback control 7 can, for example, be passed on in the form of the
 signal 75b representing a vertical velocity value in combination with the
 specified or given velocity or in the form of position data for the
 coupling path 25. As of a certain time point of the coupling procedure,
 that is, when a distance to the destination path falls below a certain
 distance, all non-linear limiters become ineffective and the control
 circuit obtains or assumes linear properties or characteristics. Thereby,
 and in connection with a preset attenuation with the value one, a coupling
 path 25 is generated that approaches the destination path 20, including
 one having any curvature characteristic and merges into the destination
 path without overshooting. The altitude difference or the difference in
 the climbing rate between the coupling path 25 and the destination path 20
 are steady and decrease monotonously down to the value zero, because the
 attenuation is equal to one. Because of the two integrators connected in
 series, and due to a destination path without jumps in the climbing rate,
 the coupling path also does not have jumps in the climbing rate, that is,
 it is free of breaks. With the help of a limit for the distance between
 coupling path 25 and the destination path 20, it is possible to determine
 when the coupling path 25 will reach the destination path 20. When this
 time point has been reached, the path generation 3 is switched off and the
 destination path 20 is transferred to the path feedback control 7. By
 initialization with the values that were measured at the beginning for the
 destination-path rated inputs 4c, in the given use example these values
 are the altitude and the climbing rate, it is achieved that the path
 generation 3 is ready to start at any possible starting situation of the
 vehicle.
 FIG. 6 shows a further example of use of the path generation according to
 the invention. In this further example, a horizontal coupling path 25 is
 generated for a horizontally running destination path 20. This further
 example can relate to aircraft, or land vehicles or ships. In this case
 the path generation is two-dimensional. According to FIG. 6, a feedback
 control 11, a path dynamic 13, and a conversion module 15 are also
 provided in the path generation 3 of the invention. Destination path data
 or values 5 are fed by the conversion module 15 to the feedback control
 11, which further receives the feedback data or values 16 from the path
 dynamic 13 and feedback 17 from the conversion module 15. To initialize
 the process, initialization values or signals 4a are fed to the path
 dynamic 13 and, among other things, serve as initial values for the
 integrators provided in the path dynamic 13. Furthermore, at the begin of
 the process, mode of operation data 4b and destination-path specified or
 rated inputs 4c are fed to the feedback control 11. In the example
 according to FIG. 6, the destination-path specified or rated inputs 4c
 receive preferably the value zero for the rated distance between the
 coupling path 25 and the destination path 20.
 In the example of FIG. 6, the destination path data or values 5 are
 preferably selected from the following: the destination path angle
 component or value 101a in the x-y coordinate system 29a (FIG. 3) or the
 destination path velocity component or value 101, respectively in the
 direction of the coupling path 25, the destination path lateral
 acceleration component or value or the destination path curvature
 component or value 102 in the direction of the coupling path 25, and the
 change of the destination path lateral acceleration component or value or
 the change of the destination path curvature component or value 103,
 respectively, in the direction of the coupling path 25. The above
 mentioned change has reference to time or to the distance of the
 destination path 20 from the coupling path 25. Furthermore, in the present
 example of FIG. 6, the lateral acceleration or curvature value 105 of the
 coupling path 25 and the coupling path direction angle value 106,
 designated in the x-y coordinate system 29a of FIG. 3 with the reference
 number 101b, or the coupling path velocity value 107, for example, formed
 respectively in the direction of the destination path 20 for the feedback
 16. The distance value 27a shown in FIG. 3 between the destination path 20
 and the coupling path 25 is used for the feedback 17, whereby the distance
 is to be defined depending on the particular type of use and depending on
 the generation phase.
 Referring further to FIG. 6, within the feedback control 11 the coupling
 path velocity values 107 are subtracted from the destination-path rated
 inputs 4c by the difference forming circuit 111. The resulting output
 signal at the output of the circuit 111 is fed to an amplifier 112 and
 then to a limiter circuit 113. Then, the destination path velocity value
 101 is added to the feedback control signal and the coupling path
 direction angle value 106 is subtracted by a summing circuit 114
 downstream of the limiter circuit 113. The feedback control signal is then
 amplified by an amplifier 115 and the destination path lateral
 acceleration or curvature value 102 is added to the signal. Optionally,
 the lateral acceleration or curvature value 105 is subtracted by a summing
 circuit 117 from the feedback signal. Downstream of the summing circuit
 117 the feedback control signal is preferably again amplified by a further
 amplifier 118 and a further limiter 118'. Finally, still optionally, the
 change of the destination path lateral acceleration or curvature value 103
 is added by an adder 116, whereby the data or values or signals 12 are
 formed which are fed to the path dynamic 13.
 The described structure of the feedback control 11 may include additional
 transmission or circuit elements or it may comprise a lesser number of
 circuit elements. Additional conventional circuit structures can also be
 integrated into the feedback control 11, for example, an input control
 device in order to accelerate the feedback control.
 Furthermore, not all destination path data or values 5 or 101, 102, 103
 must be fed to the feedback control 11 in a calculation cycle. Depending
 on the type of use and on the phase of the generation process, none or a
 subset of the values 101, 102, 103 can be fed to the feedback control 11.
 In the path dynamic 13 the signal is fed optionally to a dynamic circuit
 120 and then, depending on the type of use, to additional transmission
 elements 121 such as amplifiers or limiters. The resulting or output
 signal 123 for the coupling path direction angle then forms the feedback
 data or signals 16 which in FIG. 6 are the coupling path angular direction
 signal or value 106 or the velocity value 107 which are fed to the
 feedback control 11. A kinematic cross-linking circuit 127 receives the
 output signal 123. This cross-linking operation reprocesses the coupling
 path direction value 106 or velocity 107 in the direction of the
 destination path 20 into the derivations over time of the values of the
 corresponding two-dimensional coordinates. Essentially geometrical
 operations are carried out in the kinematic cross-linking circuit 127. The
 data or values or signals 127a for the first dimension or coordinate are
 fed to an integrator circuit 128a, and the data or signals or values 127b
 for the second dimension or coordinate are fed to an integrator 128b,
 whereby the feedback values or signals receive a value that corresponds to
 the coordinates of the coupling path 25 and which are fed to the path
 feedback control 7 or 11. These data or signals are then fed to the
 conversion module 15 which, in the present example, calculates the
 distance components, the angle components, the curvature components and
 the lateral acceleration components of the destination path 20, and thus,
 calculates the destination path data or signals or values 5 or 101, 102,
 103.
 The process of path generation takes place preferably in several phases.
 Depending on the type of use and on the phase for which the path
 generation 3 generates the data or signals for the coupling path 25,
 single control loops cannot be operated in the feedback control 11 and/or
 in the conversion module 15. Thus, for example, there is no feedback of
 the distance value 27a. Individual destination path data or values or
 signals 5 cannot be used; so that, for example, there is no destination
 path lateral acceleration or curvature value 102.
 Which phases within a path generation process and which switchovers into a
 next phase can be provided will now be described in the following example
 with further reference to the example of use according to FIG. 6.
 The switch-over into the next phase is done preferably, depending on the
 distance value between the coupling path coordinates and the destination
 path coordinates. Such distance value exists in a calculation cycle. In
 this context, preferably the distance taken into account is the shortest
 distance in a calculation cycle between the relevant coordinates of the
 coupling path 25 and of the destination path 20.
 The first phase is then activated in case the vehicle has a distance
 greater than a specified value, for example 1000 m, to the destination
 path. In this first phase, the complete path generation 3 according to the
 invention is not in operation. Rather, only a destination path direction
 feedback control of the vehicle is performed and that, for example,
 perpendicularly to the destination path 20. Thereby, the value
 +/-90.degree. is added to the destination path angle value 101a. The
 destination path lateral curvature value 102 and the feedback 17 or
 coupling path velocity value 107 are not fed back, while the coupling path
 angular direction value 106 is fed back.
 In the second phase that begins when the vehicle has a lesser distance to
 the destination path 20 than the specified value, the vehicle swings into
 the direction of the destination path 20. In this second phase, the path
 generation 3 according to the invention is thus also not completely in
 operation and only the destination path angle value 101a without, however,
 adding the +/-90.degree. and the coupling path direction value 106 are fed
 back.
 The third phase begins when the vehicle has turned in a direction that lies
 at the most in a certain angle relative to the relevant section of the
 destination path 20. In this case the data or values 4a, 4b, 4c are first
 fed to the corresponding modules of the path generation 3 for activating
 the generation. Preferably, the destination path data or values 5 or 101,
 102, 103 and the feedback data or values 16, 17 or 105, 106, 107 are then
 switched on stepwise or altogether, whereby also a subset of the
 destination path data or values 101, 102, 103 and of the feedback data or
 values 106, 107 are also completely fed back.
 The path generation 3 continues to work in the third phase until the
 distance between the coupling path 25 and the destination path 20 has
 achieved a predetermined limit value. At this time the fourth phase of the
 path generation process begins. In this phase the data of the destination
 path 20 are fed directly to their path feedback control 7, which means the
 path generation 3 can be deactivated.
 The path generations according to the FIGS. 5 and 6 can be switched
 together to generate a three-dimensional coupling path. In this context, a
 limiter circuit 76 with the limiting values is required to keep the rise
 or slopes of the vertical component or value of the coupling path are
 sufficiently small so that the velocity in the horizontal track does not
 change too strongly. The velocity in the horizontal plane can then be
 assumed to be constant so that a switching together of both path
 generations according to the FIGS. 5 and 6 is achieved with a relatively
 modest modification effort.
 Several methods or systems according to FIGS. 1 and 2 or several example
 embodiments based on FIGS. 5 and 6 can be combined for a multi-dimensional
 path generation. This can be done by taking into consideration more than
 one dimension for the coupling path, for example, by using additional
 velocity or acceleration progressions or characteristics. Signal and data
 flows, in particular between the physically corresponding values, are
 created in such a combination of FIGS. 1 and 2 or 5 and 6.
 It is emphasized that as destination path data or values there may be also
 provided only individual ones of the destination path data or values 51,
 52, 53, 54 or 101, 102, 103 or combinations of the destination path data
 or values shown in FIGS. 5 and 6, or values that are mathematically and
 physically equivalent to destination path data or values.
 With the invention, the non-linear components in the last approach phase of
 the coupling path 25 to the destination path 20 are eliminated in the
 feedback control 11. Consequently, the feedback control 11 described above
 can be referred to as being based on a linear construction method. A
 corresponding structure of the feedback control 11 can be seen in FIGS. 5
 and 6. However, the feedback control 11 can also be constructed
 differently, in contrast to these Figs. In particular, the feedback
 control 11 can also be embodied on the basis of non-linear construction
 methods, that is, the control is non-linear even in the final approach
 phase of the coupling path 25 to the destination path 20.
 Although the invention has been described with reference to specific
 example embodiments, it will be appreciated that it is intended to cover
 all modifications and equivalents within the scope of the appended claims.
 It should also be understood that the present disclosure includes all
 possible combinations of any individual features recited in any of the
 appended claims.