United States Patent [191
`Thornberg et al.
`
`llllllllllllllIllIlllllllllllllll||l|l|||llllllllllllllllllllllllllllllllll
`5,552,983
`Sep. 3, 1996
`
`US005552983A
`Patent Number:
`[11]
`[45] Date of Patent:
`
`[54]
`
`[75]
`
`VARIABLE REFERENCED CONTROL
`SYSTEM FOR REMOTELY OPERATED
`VEHICLES
`
`Inventors: Christopher A. Thornberg, Newtown;
`Bryan S. Cotton, Monroe, both of
`Conn.
`
`[73]
`
`Assignee: United Technologies Corporation,
`Hartford, Conn.
`
`[21]
`[22]
`[51]
`[52]
`
`[58]
`
`[56]
`
`Appl. No.: 204,706
`Filed:
`Mar. 2, 1994
`
`Int. Cl.6 ................................................. .. G061?‘ 165/00
`US. Cl. ................................... .. 364l424.01; 244/311;
`341/176; 180/167
`Field of Search ............................. .. 364/424.0l, 434,
`364/559, 424.02; 180/167; 244/311, 3.14,
`190; 340/825.72; 341/176
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`Primary Examiner-Michael Zanelli
`Attorney, Agent, or Firm-—Michael Grillo
`
`ABSTRACT
`[57]
`A frame of reference is selected, and control inputs provided
`by a vehicle operator are transformed to account for the
`orientation of a remotely operated vehicle with respect to the
`selected frame of reference such that the remotely operated
`vehicle responds to the control inputs with respect to the
`selected frame of reference. An earth frame of reference may
`be selected based on a ?xed true heading, e.g., North, or
`based on the initial orientation of the vehicle operator.
`Alternatively, a vehicle frame of reference may be selected
`which provides a ?xed frame of reference with respect to the
`vehicle and a variable frame of reference with respect to the
`vehicle operator. A vehicle operator frame of reference may
`also be selected based on the orientation of the vehicle
`operator with respect to earth, and control commands are
`transformed based on changes in both the operator orienta
`tion with respect to the earth reference and the remotely
`operated vehicle orientation with respect to the earth refer
`ence, which provides a ?xed frame of reference with respect
`to the vehicle operator and a variable frame of reference with
`respect to the vehicle. The remotely operated vehicle head
`ing transformation may be based on a selected forward, ?xed
`or variable point on the vehicle related to a vehicle center of
`gravity, a forward part of the vehicle, the location of a sensor
`on the vehicle, or some other arbitrary reference location on
`the vehicle.
`
`Simonoff ............................... .. 341/176
`Rue etal. ..
`178/68
`
`8/1995
`l/l971
`9/1983
`12/1987
`Hatton et al.
`12/1990 Shatford et a1. ..... ..
`7/1993 Schoenberger et a1.
`
`Kanaly . . . . . . . . . . .
`
`H1469
`3,557,304
`4,405,943
`4,714,140
`4,976,435
`5,226,204
`FOREIGN PATENT DOCUMENTS
`
`. . . .. 358/133
`
`.... .. 180/20
`273/148 B
`.... .. 14/715
`
`0522829
`
`l/l993 European Pat. Off. .
`
`7 Claims, 4 Drawing Sheets
`
`

`

`US. Patent
`FIG.1 A
`
`VEHICLE
`
`Sep. 3, 1996
`
`Sheet 1 of 4
`
`5,552,983
`
`VEHICLE
`MOTION
`
`FIG.2
`
`VEHICLE
`MOTION
`
`FORWARD
`
`LEFT @l RIGHT
`
`AFT
`
`FORWARD
`
`LEFT'@ RIGHT
`
`SENSOR @5245
`
`FOWARD
`
`VEHICLE
`REFERENCE
`
`257
`
`(3!.
`
`\ VEHICLE
`I)
`,
`MAP
`OPERATOR
`REFERENCE
`MODE
`
`200
`
`209
`
`FORWARD
`205
`
`LEFT
`
`RIGHT
`
`ALTITUDE
`CONTROL
`
`ENGINE
`SPEED
`CONTROL
`
`AFT
`
`PITCH/ROLL
`
`

`

`US. Patent
`US. Patent
`
`Sep. 3, 1996
`Sep. 3, 1996
`
`Sheet 2 of 4
`Sheet 2 0f 4
`
`5,552,983
`5,552,983
`
`
`
`38
`
`26
`
`0
`
`26
`
`(If ‘HI
`
`24
`
`60
`/
`
`IOO \ 50 N
`
`FIG/1
`
`Page 3 of 9
`
`42
`
`

`

`US. Patent
`
`Sep. 3, 1996
`
`Sheet 3 of 4
`
`5,552,983
`
`
`
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`US. Patent
`
`Sep. 3, 1996
`
`Sheet 4 of 4
`
`5,552,983
`
`FIG.6
`
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`NAVIGATION
`
`36
`
`Page 5 of 9
`
`

`

`5,552,983
`
`1
`VARIABLE REFERENCED CONTROL
`SYSTEM FOR REMOTELY OPERATED
`VEHICLES
`
`TECHNICAL FIELD
`
`The present invention relates to the control of remotely
`operated vehicles, and more particularly to a variable ref
`erence for the control of a remotely operated vehicle.
`
`BACKGROUND OF THE INVENTION
`
`2
`Therefore, existing methods for controlling remotely
`operated vehicles rely greatly on operator skill. With a
`considerable amount of training, an operator can learn to
`operate a remotely operated vehicle pro?ciently in most
`spatial relationships of the vehicle with respect to the
`operator. However, under high workload and stress condi
`tions, the non-intuitive control of a remotely operated
`vehicle may result in inadvertent and unwanted motion of
`the remotely operated vehicle.
`
`DISCLOSURE OF THE INVENTION
`
`Objects of the invention include the provision of an
`improved control system for controlling a remotely operated
`vehicle which provides a variable frame of reference for
`control of the remotely operated vehicle.
`Another object of the present invention is to provide a
`control system for a remotely operated vehicle which allows
`a vehicle operator to select a vehicle reference axis for
`purposes of determining the control response of the vehicle.
`A further object of the present invention is to provide a
`vehicle control system for a remotely operated vehicle
`which allows the vehicle operator to select between a
`vehicle frame of reference, an earth frame of reference, and
`a variable frame of reference for controlling the operation of
`a remotely operated vehicle.
`According to the present invention, a frame of reference
`is selected, and control inputs provided by a vehicle operator
`are transformed to account for the orientation of a remotely
`operated vehicle with respect to the selected frame of
`reference such that the remotely operated vehicle responds
`to the control inputs with respect to the selected frame of
`reference.
`'
`In further accord with the present invention, an earth
`frame of reference may be selected based on a ?xed heading,
`e.g., North, or based on the initial orientation of the vehicle
`operator. Alternatively, a vehicle frame of reference may be
`selected which provides a ?xed frame of reference with
`respect to the vehicle and a variable frame of reference with
`respect to the vehicle operator. A vehicle operator frame of
`reference may also be selected based on the orientation of
`the vehicle operator with respect to earth, and control
`commands are transformed based on changes in both the
`operator orientation with respect to the earth reference and
`the remotely operated vehicle orientation with respect to the
`earth reference, which provides a ?xed frame of reference
`with respect to the vehicle operator and a variable frame of
`reference with respect to the vehicle.
`In still further accord with the present invention, the
`remotely operated vehicle heading transformation may be
`based on a selected forward, ?xed or variable point on the
`vehicle related to a vehicle center of gravity, a forward part
`of the vehicle, the location of a sensor on the vehicle, or
`some other arbitrary reference location on the vehicle.
`The present invention provides a simpli?ed control of a
`remotely operated vehicle by allowing the vehicle operator
`to select a frame of reference for control signals based on a
`vehicle operator reference or a ?xed earth reference as
`opposed to a vehicle reference. A ?xed earth reference is
`particularly useful when controlling vehicle motion based on
`the indicated location of the vehicle on an electronic map,
`the map having a ?xed earth frame of reference. Therefore,
`the invention allows an unskilled or relatively inexperienced
`operator to control a remotely operated vehicle without the
`associated disorientation when the vehicle movements
`become non-intuitive, as in the prior art. Additionally, by
`
`There are a variety of uses for remotely operated vehicles
`including military, industrial and entertainment/recreation
`applications. For entertainment/recreation applications,
`remotely operated model airplanes, helicopters, automo
`biles, ships and sail boats are well known. In an industrial
`application, it is well known to use a remotely operated
`vehicle to complete high risk or di?icult tasks such as
`inspection, maintenance and repair in a high radiation area,
`exploration of extreme water depths, and airborne surveil
`lance.
`Within the military spectrum, there has been a recent
`resurgence in the interest in unmanned aerial vehicles
`(UAVs) for performing a variety of missions where the use
`of manned ?ight vehicles is not deemed appropriate, for
`whatever reason. Such missions include surveillance, recog
`nizance, target acquisition and/or designation, data acquisi
`tion, communication data linking, decoy, jamming, harass
`ment, or one way supply ?ights. Similarly, it has long been
`the practice of remotely controlling torpedo’ s for underwater
`delivery of ordinance.
`An obvious difference between a manned and remotely
`operated vehicle relates to the control or pilotage of the
`vehicle. In a manned vehicle, the operator sits within the
`vehicle and inputs control signals related to the desired
`vehicle response. In such a case, all requests by the vehicle
`operator are based on a vehicle frame of reference. For
`example, in an aircraft, control requests are typically input
`by a pilot via a control stick. If the pilot wishes to move the
`aircraft forward, he inputs a forward movement of the
`control stick, which pitches the aircraft in the forward
`direction. Similarly, if the pilot wishes to move the aircraft
`to the right, he inputs a right lateral stick motion which, in
`turn, rolls the aircraft to the right.
`A problem associated with operating remotely operated
`vehicles is that when the vehicle operator controls the
`vehicle from a distant location, commands referenced to the
`operator’ s body or operator frame of reference may result in
`undesired vehicle motion. Typically, the motion of a
`remotely operated vehicle is governed by the direction in
`which a ?xed reference point or axis on the vehicle is
`pointing, e.g., the direction that the vehicle nose or front is
`pointing. Referring to the example of FIG. 1, if the vehicle
`operator 10 and the vehicle 12 have the same forward
`orientation or frame of reference, then control inputs by the
`vehicle operator 10 will result in a corresponding change in
`vehicle motion, e.g., if the vehicle operator commands a
`right motion of the vehicle, the vehicle 12 will move/turn to
`the right. However, as shown in the example of FIG. 2, if the
`vehicle is moving towards the vehicle operator 10 then a
`control input by the vehicle operator will result in opposite
`motion of the vehicle, e.g., if the vehicle operator commands
`a right motion of the vehicle, the vehicle will actually
`move/turn left with respect to the vehicle operator.
`
`20
`
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`
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`
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`
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`
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`
`

`

`5,552,983
`
`3
`allowing the remotely operated vehicle heading transforma
`tion to be based on the location of a sensor on the vehicle,
`the vehicle may be controlled such that variations in control
`inputs will control the pointing direction of the sensor.
`The foregoing and other objects, features and advantages
`of the present invention will become more apparent in the
`following detailed description of exemplary embodiments
`thereof, as illustrated in the accompanying drawings.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is a schematic block diagram of a remotely
`operated vehicle and an operator control panel showing
`vehicle response to control inputs when the vehicle and
`control panel share the same frame of reference;
`FIG. 2 is a schematic block diagram of a remotely
`operated vehicle and an operator control panel showing
`vehicle response to control inputs when the vehicle and
`control panel have opposing frames of reference;
`FIG. 3 is a perspective view, partially broken away, of a
`remotely operated vehicle having a variable referenced
`control system of the present invention;
`FIG. 4 is a schematic block diagram, partially broken
`away, of an operator control panel used with the remotely
`operated vehicle of FIG. 3;
`FIG. 5 is a schematic block diagram showing the trans
`mission of control signals from the operator control panel of
`FIG. 4 to the remotely operated vehicle of FIG. 3; and
`FIG. 6 is a schematic block diagram showing the com
`mand transformation utilized by a ?ight control computer of
`the remotely operated vehicle of FIG. 3.
`
`15
`
`20
`
`25
`
`BEST MODE FOR CARRYING OUT THE
`INVENTION
`
`35
`
`4
`which are attached to the rotor assembly 60 and are opera
`tive to supported the rotor assembly 60 in ?xed coaxial
`relation with respect to the toroidal ?iselage 20. The toroidal
`fuselage 20 contains forward located internal bays 26 which
`are typically utilized for sundry ?ight/mission equipment 30
`as described herein below. Mission payload equipment 32 is
`preferably located, but not limited to, the internal bay 26.
`Generally the mission payload equipment 32 will consist of
`some types of passive sensors, e.g., infrared detectors,
`television cameras, etc., and/or active devices, e.g., lasers,
`radio communications gear, radar, etc., and the associated
`processing equipment. Other ?ight/mission equipment 30
`such as avionics 34, navigation equipment 36, ?ight com
`puter 38, communications gear 40 (for relaying real time
`sensor data and receiving real time command input signals),
`antenna, etc., are distributed in the various internal bays 26
`as shown for example in FIG. 1. Distribution of the various
`?ight/mission equipment 30 is optimized in conjunction
`with the placement of a power plant subsystem 50 within the
`toroidal fuselage 20.
`The ?ight/mission equipment 30 described thus far is
`exemplary of the type which may be used in a UAV.
`However, as will be understood by those skilled in the art,
`a separate ?ight control computer, avionics, and navigation
`system are not necessarily required in order to perform the
`functions identi?ed in the present invention. Alternatively, a
`single ?ight control computer or mission computer may be
`provided to perform the above identi?ed functions.
`Referring to FIG. 4, a control panel 200 for remote
`operator control of the UAV 100 (FIG. 1) is shown. The
`control panel 200 is provided with a joy stick or control stick
`205 for providing control inputs to control the operation of
`the UAV. The control stick 205 is shown as being a two axis
`control stick wherein forward and aft movement of the
`control stick relates to pitch, and side-to-side movement of
`the control stick related to roll. A control panel computer 209
`is provided for receiving the control commands provided by
`the control stick 205 and converting them into is signals to
`be transmitted via by communications equipment 212. The
`communications equipment 212 comprises a transmitter 215
`for receiving the control commands provided from the
`control panel computer 209 and for transmitting the control
`commands via a control panel antenna 220.
`Referring now to FIG. 5, when control signals are trans
`mitted by the control panel via the antenna 220, the signals
`are received by the UAV antenna 42 and thereafter provided
`to the UAV communications equipment 40. The communi
`cations equipment comprises a receiver 46 and a demodu
`lator/decoder 48 for receiving and decoding the received
`signals transmitted by the control panel. Thereafter, the
`demodulated and decoded control signals are provided to the
`?ight control computer 38 and avionics equipment 34. The
`?ight control computer 38 and avionics equipment 34 pro
`cess the incoming control signals to thereby provide the
`appropriate control surface commands to the UAV control
`surfaces to perform the desired maneuvers.
`All of the apparatus described thus far is exemplary of that
`which is known in the art. In a vehicle referenced control
`system of the prior art, a ?xed reference point or location on
`the vehicle frame is selected as forward or the head of the
`vehicle, and in response to control signals, that reference
`point is maneuvered. Therefore, for example, if the operator
`inputs a right turn or roll command via the control panel, the
`UAV will turn the ?xed reference point to the right, relative
`to the UAV frame of reference. However, depending on the
`orientation of the UAV with respect to the operator, a right
`turn command input by the operator at the UAV controller
`
`The variable referenced control system for a remotely
`operated vehicle of the present invention is particularly well
`suited for allowing the optimum control of a remotely
`operated vehicle based on both operator and mission con
`siderations. The system provides for the referencing of
`vehicle commands based on an operator frame of reference
`so that control commands provided by the operator remain
`intuitive and independent of the orientation of the vehicle
`with respect to the operator. Additionally, the system pro
`vides for the referencing of vehicle position based on a
`vehicle sensor, thereby allowing the operator to easily
`control the pointed direction of a sensor on the vehicle for
`improved accuracy in the receipt of intelligence. A further
`advantage of providing a ?xed reference for a remotely
`operated vehicle is the ease of controlling the vehicle when
`the position of the vehicle is indicated on an electronic map
`having a ?xed frame of reference.
`The present invention will be described in the context of
`an unmanned aerial vehicle (UAV). However, it will be
`understood by those skilled in the art that the variable
`referenced control system of the present invention may be
`applied to any remotely operated vehicle provided that the
`vehicle contains a navigation system or other means for
`determining changes in vehicle orientation with respect to an
`operator or ?xed frame of reference.
`Referring to FIG. 3, one embodiment of an UAV 100 is
`shown. The UAV used in the example of the present inven-'
`tion comprises a toroidal fuselage or shroud 20 having an
`aerodynamic pro?le, ?ight/mission equipment 30, a power
`plant subsystem 50, and a rotor assembly 60. The toroidal
`fuselage 20 is provided with a plurality of support struts 24
`
`40
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`

`5,552,983
`
`5
`may look like a left turn to the operator if the UAV is heading
`towards the operator or if the UAV is “behind” the operator.
`The variable referenced control system of the present
`invention allows the operator to select various different
`frames of reference for controlling the UAV, thereby allow
`ing the operator to tailor the UAV control to the speci?c
`mission or operational requirements, and thereby provided
`for a simpli?ed, intuitive control.
`Referring to FIG. 6, the ?ight control computer is pro
`vided with a stick transformation function 400 which allows
`the operator to select between a variety of control references
`for controlling the remotely operated vehicle. A speci?c
`reference may be selected by repositioning a switch or
`entering a command on the control panel 200 (FIG. 2).
`Thereafter, the reference command is provided via the
`communications equipment and control panel antenna to the
`?ight control computer via the communications equipment
`on the remotely operated vehicle.
`The stick transfonnation function 400 is responsive to
`control signals received from the control panel and vehicle
`heading information for controlling the vehicle in accor
`dance with the desired mode and reference. The pitch
`command (provided from the control panel via the vehicle
`communications equipment) is provided on a line 405 to a
`pitch axis transformation function 410 and a roll axis
`transformation function 412. Similarly, the roll command is
`provided on a line 415 to the pitch axis transformation
`function 410 and the roll axis transformation function 412.
`The other input to the pitch axis transformation function 410
`and the roll axis transformation function 412 is a transfor
`mation angle (9). The transformation angle is determined
`based on the true heading of the vehicle as determined by the
`navigation system 36 and the desired vehicle reference and
`vehicle reference mode.
`The vehicle’s true heading is provided from the naviga
`tion equipment 36 on the vehicle, e.g., a ring laser gyro or
`an inertial navigation system. The true heading signal is
`indicative of the orientation of a ?xed point on the aircraft
`with respect to true north. Typically, the reference point on
`the vehicle is determined to be the forward section on the
`vehicle as determined by design or other method such as
`using a center of gravity calculation. The center of gravity is
`used for the toroidal shape because the forward ?ight
`characteristics of the vehicle are improved. The true heading
`signal provided by the navigation system 36 is provided on
`a line 420 to a summing junction 425. The other input to the
`summing junction 425 is a reference heading signal on a line
`460 which is provided as the output of a summing junction
`450.
`One input to the summing junction 450 is a vehicle
`reference signal on a line 435 provided by a vehicle refer
`ence switch 445. The operation of the vehicle reference
`switch 445 is dependent upon the position of a control panel
`vehicle reference switch 245 on the control panel 200 (FIG.
`4). If the control panel vehicle reference switch 245 is in the
`forward reference position, then the vehicle reference for
`purposes of vehicle control is the forward reference position
`on the aircraft. However, if the control panel vehicle refer
`ence switch 245 is in the sensor reference position then
`control of the vehicle will be based on the sensor position on
`the vehicle. Therefore, the signal on the line 435 will be
`equal to the angular position between the forward position
`on the vehicle and the sensor position on the vehicle. The
`angular position between the forward position on the vehicle
`and the sensor position on the vehicle is de?ned as an offset
`angle ((1)). The other input to the summing junction 450 is a
`
`6
`reference mode signal on a line 453 provided by a reference
`mode switch 457. The operation of the reference mode
`switch 457 is dependent upon the position of a control panel
`reference mode switch 257 on the control panel 200 (FIG.
`4). In a vehicle reference mode, the vehicles reference axis
`is used for purposes of controlling the vehicle from the
`control panel. In a map reference mode, an earth reference,
`such as North, is used for control of the vehicle. In an
`operator reference mode, the orientation of the operator
`upon activation of the operator mode is used as the reference
`axis. The output of the summing junction 450 is the refer
`ence heading signal on line 460 which is provided to the
`summing junction 425. The output of the summing junction
`425 is the transformation angle, and is provided on a line 467
`to the pitch axis transformation 410 and the roll axis
`transformation 412.
`The pitch axis transformation 410 uses equation 1 below
`for determining a transformed pitch stick signal (TPSS) to
`be provided on the line 470 to the pitch ?ight control system:
`
`15
`
`TPSS=pitch command * cos(6)—roll command * sin(6)
`
`(eq. 1)
`
`Similarly, the roll axis transformation 412 using equation
`2 below to provide a transformed roll stick signal (TRSS) on
`a line 475 to the roll ?ight control system:
`
`25
`
`TRSS=roll command * cos(6)+pitch command * sin(6)
`
`(eq. 2)
`
`30
`
`35
`
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`65
`
`The operation of the invention is best understood by
`example. When the vehicle is being operated in the normal
`mode wherein the vehicle reference is the forward vehicle
`axis and in the vehicle reference mode, then the transfor
`mation function should not make any change in the pitch
`command 405 and roll command 415 being provided to the
`lines 470 and 475, i.e., TPSS=pitch command and TRSS=
`roll command. The vehicle heading signal is provided on the
`line 420 to the summing junction 425. The forward reference
`signal, which is zero, is provided on the line 435 to the
`summing junction 450. Additionally, in the vehicle reference
`mode, the vehicle heading is provided via the switch 457 on
`the line 453 to the summing junction 450. The output of the
`summing junction 450 is the vehicle heading on the line 460
`which is subtracted from the vehicle heading signal on the
`line 420 in the summing junction 425. Therefore, the output
`of the summing junction 425 is zero on the line 467, and
`referring to equations 1 and 2, TPSS on the line 470 is equal
`to the pitch command on the line 405 and TRSS on the line
`475 is equal to the roll command on the line 415 when the
`transformation angle is equal to zero.
`When the vehicle is operating with a sensor reference in
`the vehicle reference mode, control inputs by the operator
`will cause the position of the vehicle sensor to change with
`respect to a vehicle frame of reference. In FIG. 6, the switch
`445 will be in the sensor reference position, and a signal
`indicative of the angular position of the sensor with respect
`to the forward reference axis of the vehicle is provided on
`the line 435 to the summing junction 450, the other input to
`the summing junction 450 being the vehicle heading signal
`on the line 453. Therefore, the transformation angle will be
`the sensor reference angular position on the line 467. There
`fore, TPSS and TRSS will be transformed by an amount
`corresponding to the angular position of the sensor reference
`with respect to the forward reference axis of the vehicle in
`the transformation functions 410, 412.
`The map reference mode of operation is particularly
`useful when controlling the position of the vehicle using an
`electronic map, the electronic map having a ?xed frame of
`
`

`

`5,552,983
`
`7
`reference, e. g., North. In this case, both the operator control
`panel and the vehicle operate with respect to the ?xed frame
`of reference. During operation with a vehicle forward ref
`erence in the map reference mode, the output of the sum
`ming junction 450 is a signal indicative of the selected
`reference, e.g., North. Therefore, the transformation angle
`output from the summing junction 425 will be indicative of
`the difference between vehicle heading and the reference
`heading. In equations 1 and 2, the pitch command and roll
`command are transformed based on the difference between
`the aircraft heading and the map reference heading. If the
`map reference mode is used with a sensor reference, then the
`angular position of the sensor with respect to the vehicle
`forward reference axis is added to the map reference in the
`summing junction 450. Therefore, the transformations 410,
`412 will also account for the angular difference between the
`sensor and the vehicle forward reference axis during the
`transformation of the pitch command and the roll command.
`The operation of the operator reference mode illustrated
`in FIG. 6 is basically identical to the operation of the map
`reference mode illustrated in FIG. 6, except that the refer
`ence axis for purposes of transformation is based on the
`orientation of the operator control panel upon activation of
`the operator reference mode. Therefore, if the operator is
`facing North upon activation of the operator mode, the North
`reference will be provided on the line 453.
`A problem associated with a ?xed operator reference
`during operation in the operator reference mode is that if the
`operator changes position during remote operation of the
`vehicle, the ?xed frame of reference no longer provides the
`advantage of intuitive roll and pitch commands. To over
`come this short coming, a variable operator reference mode
`may be provided wherein the operator reference changes
`based upon changes in the orientation of the operator control
`panel. This may be accomplished by mounting the operator
`control panel on a pedestal and providing a servo or gyro
`signal indicative of the change in the position of the control
`panel With respect to the initial operator reference. Alter
`natively, the operator control panel may be provided with a
`precise position indicator such as a ring laser gyro or inertial
`position system so that changes in the position of the control
`panel will result in changes in the operator reference posi
`tion.
`The present invention was described in the context of an
`unmanned aerial vehicle because of the more complex
`control associated with airborne vehicles. However, it will
`be understood by those skilled in the art that the variable
`referenced control system of the present invention is appli
`cable to any remotely operated vehicle provided that means
`are provided to deternrine the orientation of the vehicle with
`respect to the selected reference. The vehicle may be pro
`vided with an onboard navigation system, or means may be
`provided to externally sense the orientation of the vehicle
`with respect to the reference axis.
`Although the invention has been described and illustrated
`with respect to exemplary embodiments thereof, it should be
`understood by those skilled in the art that the foregoing and
`various other changes, orrrissions, and additions may be
`made therein and thereto, without departing from the spirit
`and scope of the present invention.
`We claim:
`1. A variable referenced control system for controlling the
`operation of a remotely operated vehicle, comprising:
`control means for providing control signals;
`means for selecting between a ?xed frame of reference
`with respect to the remotely operated vehicle, a ?xed
`
`8
`frame of reference with respect to earth, and a ?xed
`frame of reference with respect to said control means;
`means for providing transformation angle signals (9)
`indicative of the orientation of the remotely operated
`vehicle with respect to said selected frame of reference;
`and
`transformation means responsive to said control signals
`and said transformation angle signals for providing
`transformed control signals which control the motion of
`the remotely operated vehicle with respect to said
`selected frame of reference.
`2. The variable referenced control system according to
`claim 1 further comprising means for selecting a reference
`location on the remotely operated vehicle, said transforma
`tion means being responsive to said reference location for
`controlling the motion of said reference location with
`respect to said selected frame of reference in response to said
`control signals and said transformation angle signals.
`3. The variable referenced control system according to
`claim 2 wherein the angular orientation between said refer
`ence location and a ?xed reference location on the remotely
`operated vehicle is de?ned by an offset angle (r13).
`4. The variable referenced control system according to
`claim 3 wherein said control means provides control signals
`in an orthogonal axis system with respect to said control
`means, said orthogonal axis system being de?ned by an x
`direction and a y direction orthogonal to said x direction,
`said control means providing x control signals in said x
`direction and y control signals in said y direction.
`5. The variable referenced control system according to
`claim 4 wherein said transformation means provides x
`transformed control signals in said x direction de?ned by the
`following relationship:
`
`LII
`
`10
`
`20
`
`25
`
`35
`
`x transformed control signal:x control signal * cos (9—¢)—y con
`trol signal * sin (9-11))
`
`40
`
`and wherein said transformation means provides y trans
`formed control signals in said y direction de?ned by the
`following relationship:
`
`y transformed control signalq control signal * cos (6—¢)+x con
`trol signal * sin (9—¢).
`
`45
`
`50
`
`55
`
`6. The variable referenced control system according to
`claim 1 wherein said control means provides control signals
`in an orthogonal axis system with respect to said control
`means, said orthogonal axis system being de?ned by an x
`direction and a y direction orthogonal to said x direction,
`said control means providing x control signals in said x
`direction and y control signals in said y direction.
`7. The variable referenced control system according to
`claim 6 wherein said transformation means provides x
`transformed control signals in said x direction de?ned by the
`following relationship:
`
`1 transformed control signal=x control signal * cos (9)—y control
`signa