(12) United States Patent
`Barr
`
`(10) Patent NO.: US 7,219,861 B1
`(45) Date of Patent:
`May 22,2007
`
`(54) GUIDANCE SYSTEM FOR
`RADIO-CONTROLLED AIRCRAFT
`
`(75)
`
`Inventor: Howard Barr, Encinitas, CA (US)
`
`(73) Assignee: Spirit International, Inc., Carrollton,
`TX (US)
`
`( * ) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 774 days.
`
`(21) Appl. No.: 091611,177
`
`(22) Filed:
`
`Jul. 6, 2000
`
`(51) Int. C1.
`B64C 13/18
`(2006.01)
`(52) U.S. C1. ...................................................... 2441190
`(58) Field of Classification Search ................ 2441189,
`2441190, 17,13; 70112
`See application file for complete search history.
`
`(56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`711964 Rhoads et al.
`1011964 Sheppard et a1
`711977 Knowlton
`611980 Meyer
`611985 Sulouff et al.
`211988 Jenkins
`411989 Hulsing, I1
`1011990 Berejik et al.
`1011991 Cycon et al.
`1111991 Heyche et al.
`311993 Collier
`
`911993 Stern
`5,249,272 A
`711994 Orton et al.
`5,329,213 A
`411995 Singhai
`5,407,149 A
`611995 Moberg
`5,425,750 A
`811995 Simonoff
`H1469 H
`911995 Nakada et al
`5,452,901 A
`411996 Yang
`5,507,455 A
`1111996 Orton
`5,577,154 A
`911997 Dixon
`5,672,086 A
`5,730,394 A * 311998 Cotton et al
`5,785,281 A
`711998 Peter et al.
`5,789,677 A
`811998 McEachern
`5,904,724 A *
`511999 Margolin
`
`FOREIGN PATENT DOCUMENTS
`
`DE
`
`196 14 987 A1
`
`411996
`
`* cited by examiner
`Primary Examiner-Tien Dinh
`(74) Attorney, Agent, or Firm-Knobbe Martens Olson &
`Bear LLP
`
`ABSTRACT
`
`A method and system are described for controlling the flight
`pattern of a remote controlled aircraft. The system includes
`a microcontroller that is linked to an accelerometer for
`determining the attitude of the aircraft and modifying signals
`to the aircraft's flight control system in order to prevent a
`crash. In addition, several preset flight patterns are stored in
`a memory so that upon activation, the aircraft will enter a
`preset flight pattern.
`
`23 Claims, 6 Drawing Sheets
`
`Parrot Ex. 1007
`
`

`

`U.S. Patent
`U.S. Patent
`
`May 22, 2007
`May 22,2007
`
`Sheet 1 of 6
`Sheet 1 of 6
`
`US 7,219,861 B1
`
`FIG.1
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`

`

`U.S. Patent
`U.S. Patent
`
`May 22,2007
`May 22, 2007
`
`Sheet 2 of 6
`Sheet 2 of 6
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`May 22,2007
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`U.S. Patent
`
`May 22,2007
`
`Sheet 4 of 6
`
`4 lo--,
`
`402--,
`(sTAART)
`4
`404 -,
`STORE SlGRIAL PROPERTIES CORRESPONDIIVG
`+
`TO LEVEL FLIGHT TO A MEMORY
`RECEIVE SIGNAL FROM TRANSMmER
`4
`4 157
`I CAPTURE SIGNAL FROM ACCELEROMETER
`STORE A1 L SlGNALS TO A MEMORY 42u0
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`SIGNALS TO MEMORY
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`
`I SEND ALL MODIFIED SIGNALS TO SERVOS
`
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`FIG. 4
`
`

`

`U.S. Patent
`
`May 22,2007
`
`Sheet 5 of 6
`
`TO REGISTERS
`
`536\
`
`CALCULATE
`CORRECTIVE SERVO
`COMMAND
`
`(534
`
`CALCULATE
`DIFFEREfiCE
`BEWEEN CURREAT
`PlTCHIROLL
`AND ZERO
`
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`
`RETRIEVE FLIGHT
`
`STORE FLIGHT COMMANDS
`TO REG/ST€RS
`
`530
`
`FIG. 5
`
`

`

`U.S. Patent
`
`May 22,2007
`
`Sheet 6 of 6
`
`I
`
`caLCrl1 ATE MOTOR SPEED, RUf i. AND PrrCH
`
`I
`
`6147
`USE TRANSMITTED
`SERVO COMMANDS
`
`MUD/FY SERM COMMANDS "I
`
`FIG. 6
`
`700 SENSOR
`7 COND~TION
`
`

`

`US 7,219,861 B1
`
`1
`GUIDANCE SYSTEM FOR
`RADIO-CONTROLLED AIRCRAFT
`
`2
`least one aircraft flight control system, wherein said control
`module comprises instructions that, when executed, send
`modified control signals to said flight control system; and a
`positioning module in communication with said control
`5 module, said positioning module providing positioning sig-
`1. Field of the Invention
`nals representing the current attitude of the aircraft to said
`control module.
`This invention relates to control systems for radio-con-
`Another embodiment of the invention is a system for
`trolled aircraft. More specifically, this invention relates to
`preventing crashes of a remote controlled aircraft that
`methods and systems for modifying the flight path of a
`l o includes: a positioning module that determines the attitude
`radio-controlled aircraft.
`2. Description of the Related Art
`of said remote controlled aircraft during flight; a control
`module in communication with said positioning module and
`The sport of flying radio-controlled aircraft has increased
`with control signals received from a transmitter; and said
`in popularity over the past several years. Many hobbyists
`control module comprising instructions for determining
`spend a tremendous amount of time building and flying
`these radio-controlled aircraft. As is known, these aircraft 1s when said aircraft is at risk of crashing and, responsive to
`are flown by a pilot that sends control signals from a
`said determination, providing modified control signals to at
`least one aircraft flight control system, wherein said modi-
`transmitter to a receiver in the aircraft.
`A remote controlled airplane changes direction by move-
`fied control signals reduce said risk of crashing said aircraft.
`ment around one or more of its three axes of rotation: lateral
`Yet another embodiment of the invention is a method of
`axis, vertical axis, and longitudinal axis. These axes are 20 modifying the flight pattern of a remote controlled aircraft.
`The method includes: reading control signals from a trans-
`imaginary lines that run perpendicularly to each other
`through the exact weight center of the airplane. The air-
`mitter; reading positioning signals corresponding to the
`plane's rotation around them is termed pitch, roll, and yaw.
`attitude of said aircraft from a positioning module; deter-
`The pilot guides the airplane by sending control signals to
`mining if said control signals will place the airplane outside
`servos within the airplane that change the pitch, roll, and 25 of defined performance parameters; and modifying said
`yaw by moving the elevators, ailerons, and rudder of the
`control signals so that performance of said airplane is within
`airplane.
`said defined performance parameters.
`Conventional remote controlled aircraft use radio fre-
`quency signals that are sent from the pilot's transmitter to a
`receiver in the airplane, which in turn generate a sequence 30
`FIG. 1 is a schematic diagram of a remote-controlled
`of frequency modulated signals. Each control surface in the
`aircraft.
`airplane is moved by a servo that receives these frequency
`FIG. 2 is a block diagram illustrating one embodiment of
`modulated signals. By, for example, increasing the fre-
`the circuitry for controlling a remote-controlled aircraft.
`quency of the signal that controls the elevator servo, the pilot
`FIG. 3 is a timing diagram illustrating processed servo
`can cause the airplane to ascend or descend. In the same 35
`signals within one embodiment of the circuitry of FIG. 2.
`manner, changing the pulse-width of the signals to the
`FIG. 4 is a flow diagram illustrating a process for sending
`aileron servo will cause the airplane to turn.
`modified signals to servos in a remote-controlled aircraft.
`Unfortunately, the chance that a beginner will success-
`FIG. 5 is a flow diagram illustrating the modify signals
`fully complete their first flight can be less than 1 in 10. This
`fact not only deters potential hobbyists from joining the 40 process of FIG. 4.
`FIG. 6 is a flow diagram illustrating the flight assist
`sport, but also adds to the cost of taking up this sport since
`process of FIG. 5.
`so many aircraft are destroyed during the learning stages.
`FIG. 7 is a block diagram illustrating an embodiment of
`One reason that so many aircraft are destroyed during the
`a sensor conditioning circuit.
`learning stage of flying remote-controlled aircraft is that no
`inexpensive and convenient system exists for assisting a 45
`novice pilot to maneuver the plane or recover from unstable
`flight situations. Some systems do exist for pilotless military
`1. Overview
`aircraft, such as one described in U.S. Pat. No. 4,964,598
`Embodiments of the present invention relate to a low-
`('598) to Berejik et al. The system described in the '598
`patent relies on feedback signals from gyroscopes in the 50 cost, electronic guidance system that is incorporated into a
`airplane to control the bank-angle and actual rate of climb of
`remote controlled airplane and is capable of modifying the
`the aircraft. While such a system might be appropriate for
`flight control signals sent by the pilot to the airplane. This
`military drones, such a system is complex and would not
`embodiment functions by modifying the control signals that
`provide a cost effective solution for radio-controlled airplane
`are sent by the pilot to the airplane. For example, if the pilot
`55 moves a control lever on the transmitter, the frequency of the
`hobbyists.
`What is needed in the art is a simple and inexpensive
`signals being sent to a receiver in the aircraft are altered. The
`system that can be incorporated into radio-controlled aircraft
`receiver in the aircraft then outputs pulse-width modulated
`systems in order to give novice pilots the ability to fly radio
`signals to a microcontroller which analyzes the signals and
`controlled aircraft without risking a crash. The present
`outputs and, after making any necessary modifications,
`60 outputs the pulse-width modulated signals to the servos that
`invention fulfills such a need.
`control flight. Each movement of the control stick by the
`pilot causes signals at one or more frequencies to be trans-
`mitted to a receiver in the aircraft. These signals are con-
`verted to pulse-width modulated signals for controlling
`One embodiment of the invention is a control system for
`remote-controlled aircraft. This embodiment includes: a 65 different servos or settings of the aircraft.
`receiver for receiving control signals from a transmitter; a
`Each command transmitted by the pilot to the aircraft
`control module in communication with said receiver and at
`affects the position of either a servo, or other flight control
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`DETAILED DESCRIPTION
`
`BACKGROUND OF THE INVENTION
`
`SUMMARY OF THE INVENTION
`
`

`

`u 2
`
`electronics. In this embodiment, the ultrasonic sensor detects
`system on the aircraft. In one embodiment, if the pilot
`objects, such as walls, and can turn to avoid them. Thus, an
`changes the flight path by modifying, for example, the
`airplane that could fly indoors by turning when a wall as
`elevator servo, a microcontroller analyzes the request, along
`detected is anticipated. In one embodiment, the aircraft
`with data from an accelerometer or other level sensing
`includes a series of transducers and drive electronics for
`device such as an inclinometer, to determine whether the 5
`determining the distance of the aircraft from other objects.
`maneuver might lead to an unstable flight. If the maneuver
`For example, the Polaroid Ultrasonics (Newton, Mass.)
`is one that might lead to an unstable flight, this system can
`modify the pulse-width of the signal from the receiver Model 6500 Series sonar ranging module can be integrated
`before being transmitted to the flight control servos, so that
`into the aircraft flight control system to report distances from
`l o other objects. Using this module, the distance from an object
`the airplane does not go out of control.
`In use, the circuitry described below detects the intended
`can be calculated based on the time of a transmit signal and
`position of each flight control system (aileron, engine, flaps,
`the leading edge of the returning echo signal. The distance
`etc.) within the aircraft, and then modifies that position
`is then calculated as the transit timeispeed of sound. The
`onboard central processor in the aircraft would then make an
`based on the current pitch and roll of the aircraft. The flight
`control systems include the mechanisms for powering and 1s evaluation of what, if any, evasive maneuver to take based
`steering the aircraft, such as the servos, engine, ailerons,
`on the distance to the object.
`2. System
`rudder and elevators.
`In one embodiment, a plurality of accelerometers, here
`Referring to FIG. 1, a radio-controlled flight system 10 is
`used as inclinometers, are located within the aircraft and
`illustrated. The system includes a remote transmitter 20 that
`provide sensed information to a microcontroller concerning 20 provides joysticks 22A,B and buttons 24A-C for sending
`frequency or amplitude modulated signals 25 to a remote-
`the current attitude of the aircraft. Instructions stored within
`the microcontroller read the intended position of each servo
`controlled aircraft 30. The aircraft 30 receives the signals 25
`from the frequencies transmitted by the ground transmitter
`via a receiver (not shown). The received signals are fed
`and thereafter modify the pulse-width of the signals to
`through the flight control circuitry, as described below in
`prevent the plane from crashing, or to enter a pre-planned 25 FIG. 2, in order to control a set of ailerons 35A,B a rudder
`flight pattern, if signaled to do so by the pilot.
`40 and an elevator 45.
`As can be imagined, adjusting the joysticks 22A,B or
`In addition to the above-referenced embodiment, other
`depressing the buttons 24A-C on the transmitter 20 sends
`embodiments of the system are available. For example, an
`emergency flight mode is provided which allows the pilot to
`signals 25 to the radio-controlled aircraft 30 that normally
`vress an "emer~encv" button on the radio transmitter that 30 move the servos which control the ailerons. rudder and
`sends a signal to the flight control circuitry instructing it to
`elevators.
`place the airplane in upright, level flight. The flight control
`FIG. 2 is a block diagram of a flight control system 100
`circuitry determines the current position of the aircraft
`that is mounted within the remote controlled airplane 30. As
`indicated, the flight control system 100 includes a radio-
`through the accelerometers, and calculates the proper servo
`vositions of the elevators. ailerons and rudder to vlace the 35 control receiver 105 that is linked to an antenna 110 for
`aircraft in level flight. Thus, the emergency button will right
`receiving frequency modulated signals in the frequency
`the aircraft from any position and place it in level flight.
`modulated system from the radio-control transmitter 20. The
`Another embodiment of the invention includes a button
`received servo signal commands are separated by the
`receiver 105 into servo signal paths 112 to a signal-condi-
`that sends a command to the flight control circuitry to
`execute a constant flight path based on the current pitch and 40 tioning circuit 115 that translates the servo signals into
`roll condition. By depressing this button, or otherwise
`appropriate digital pulse-width modulated signals (typically
`3V) by, for example, level shifting and transition sharpening
`executing a command to the flight control circuitry on the
`aircraft, the current pitch and roll condition is detected and
`the signal from the receiver. The signal conditioning circuit
`stored to a memory. The microcontroller within the system
`115 preferably converts the incoming analog waveforms into
`then continually monitors the pitch and roll of the aircraft 45 sharp square waves having a 6 5 V min-max. This prevents
`and makes any necessary adjustment in the servos to main-
`any pulse-width errors from entering the flight control
`tain the current attitude of the airplane.
`system and affecting the airplane performance. In one
`Another embodiment of the system includes a "preset"
`embodiment, the signal conditioning circuit is a Texas
`Instruments (Dallas, Tex.) 74 HCT14 integrated circuit,
`flight mode. Upon activation by the pilot, the plane will
`execute a pre-programmed flight path based upon the current 50 followed by a 74 HC14.
`pitch and roll information. For example, the pre-pro-
`The square wave pulse-width modulated signals are then
`grammed flight path might be a wide-sweeping circle. Thus,
`sent to a one-of-eight selector circuit 120 that selects each
`should the hobbyist get in trouble during a flight, this button
`conditioned frequency channel in a serial manner. As is
`on the transmitter can be activated to instruct the plane to
`shown, each frequency channel controls a separate servo, or
`correct itself from any current position. The plane will then 55 other component such as the engine, within the airplane 30.
`enter a slow, circular loop until deactivated by the pilot.
`Thus, a transmitter 20 might transmit frequency modulated
`signals along eight separate frequency channels for control-
`Once the "preset" flight mode has been entered, the plane
`ling the ailerons, propeller speed, elevator, rudder, etc. of the
`will continue with the preset flight pattern until instructed to
`aircraft 30. The selector circuit 120 individually selects each
`discontinue the pattern by receipt of a signal from the ground
`60 servo channel so that the system 100 can analyze andmodify
`transmitter.
`one channel at a time prior to outputting it to a servo. The
`The preset flight mode might include specific patterns,
`such as a figure of "X", loop or spin. Thus, the pilot could
`selector 120 chooses each channel on the leading edge of the
`enter aerobatic or complicated flight movements into a
`square wave pulse, and thereafter waits for the trailing edge
`memory in the flight control system so that these movements
`of the same channel before moving on to select the next
`65 channel in line to analyze. In this manner, the selector 120
`could be repeated over and over without risk of error.
`Another embodiment of the invention includes an ultra-
`serially transmits each channel being transmitted to the
`sonic ranging system that is integrated into the airplane
`receiver 105. As each channel is selected from the selector
`
`

`

`US 7,219,861 B1
`
`6
`5
`Also connected to the microcontroller 130 is a ZERO
`120, it is fed into a microcontroller 130 that processes all of
`READY indicator light 170, a FAULT indicator 175 and a
`the incoming signal data. In one embodiment, the micro-
`POWER indicator light 180. In use, the ZERO READY
`controller is a Motorola (Austin, Tex.) MC 68 HC711D3.
`indicator light flashes to indicate when the system is ready
`This microcontroller includes four kilobytes of on-board
`to be zeroed by the pilot. Pressing the zero switch 150 then
`Programmable Read Only Memory (PROM) for storing 5
`sets the current state of the accelerometer to a memory in the
`instructions, and 192 bytes of on-chip Random Access
`microcontroller 130. The FAULT indicator light 175 is
`Memory (RAM).
`Also feeding into the microcontroller 130 is a two-axis
`illuminated whenever a fault or error is detected within the
`flight control system 100. The POWER indicator light 180
`accelerometer 140 that provides pulse-width modulated sig-
`nals 142, 144 corresponding to the present X and Y dimen- l o is illuminated whenever power is applied to the flight control
`sional acceleration of the airplane 30, which corresponds to
`system 100.
`The microcontroller 130 outputs signals to the servos
`the airplane's pitch and roll. Several inclinometers could be
`used as accelerometers. For example, a Model LCL (The
`along a group of output connections. The output connections
`first pass through a digital signal conditioning circuit 190,
`Fredricks Company, Huntingdon Valley, Pa.) or Biaxial
`Accelerometer Model LA02-0201-1 from Humphrey (San 1s and then to an aileron servo 200, tail servo 205, motor speed
`output 210 and rudder servo 215.
`Diego, Calif.) are useful for embodiments of an accelerom-
`Referring now to FIG. 3, a timing diagram is shown,
`eter or an inclinometer. However, preferably the accelerom-
`illustrating an RF signal 301 received by the flight control
`eter is an Analog Devices (Norwood, Mass.) ADXL 202
`system, and the same servo signals 303 once they have been
`Model accelerometer. The ADXL202 is a complete 2-axis
`accelerometer with a measurement range of 22 g. The 20 processed by the flight control system and are sent to the
`ADXL202 can measure both dynamic acceleration (e.g.,
`servos. In particular, the timing signals for each servo are
`provided serially from the transmitter 20 to the receiver 105
`vibration) and static acceleration (e.g., gravity). The outputs
`in the airplane 30. For example, a signal 300 is transmitted
`of the ADXL202 are Duty Cycle Modulated (DCM) signals
`along frequency channel 1 in order to manipulate servo 1
`whose duty cycles (ratio of pulse-width to period) are
`proportional to the acceleration in each of the 2 sensitive 25 that controls the rudder. The signal 300 includes a leading
`edge 302 and trailing edge 304. The pulse-width of the
`axes. These outputs may be measured directly with a micro-
`processor counter. The DCM period is adjustable from 0.5
`signal is defined as X, and is used by the flight control
`system to calculate the angle of movement for servo 1
`If an analog output
`ms to 10 ms via a single resistor (R,.,).
`is desired, an analog output proportional to acceleration is
`(rudder). The larger the pulse-width varies from nominal, the
`available from the XFrLT and YFrLT pins, or may be recon- 30 more that servo 1 moves from its zero angle.
`As also indicated, a signal 310 corresponding to servo 2
`structed by filtering the duty cycle outputs. Furthermore,
`(ailerons) is transmitted along frequency channel 2. Signal
`filter capacitors external to these outputs are set to the
`310 includes a leading edge 312 and trailing edge 315. The
`appropriate bandwidth. This helps stabilize control of the
`pulse-width of the signal 310 is defined as Y. As shown,
`airplane due to vibrations from the motor affecting the
`35 because the analog signals from the transmitter 20 are sent
`readings from the inclinometer.
`serially, the trailing edge 304 of signal 300 aligns with the
`Because of the design of this system, the microcontroller
`130 thus receives input from the receiver 105 and the
`rising edge 312 of signal 310. As illustrated, the rising and
`accelerometer 140. Within the PROM of the microcontroller
`falling edges of the signals 320 and 325, corresponding to
`130 are instructions for receiving signals from the acceler-
`servos 3 and 4, respectively, also follow one another in a
`ometer 140 and selector 120 and determining the proper 40 serial manner.
`For this reason, and as illustrated in FIG. 3B, the outputs
`output signals to transmit to the servos. This process will be
`from the signal-conditioning device 190 (FIG. 2) process the
`discussed more completely below in the following figures.
`The microcontroller 130 also has inputs from a "Zero"
`incoming signals so that the signals sent to the server in
`switch 150 that is used to set the level flight angle for the
`embodiments of this invention are aligned in parallel. As
`aircraft 30 before take-off. By depressing the zero switch 45 illustrated, the leading edge 302 of the signal 300 aligns with
`150, the microcontroller 130 samples the current two-axis
`the leading edge 312 of the signal 310. This is also true of
`the leading edges of the other signals 320 and 325. Thus, the
`accelerometer position and determines the level flight posi-
`tion for the aircraft. This zero position can be used later
`servos that are controlled by these signals are moved simul-
`during flight by the microcontroller 130 to determine the
`taneously.
`Referring now to FIG. 4, a process for receiving and
`appropriate yaw and pitch for the aircraft when level flight 50
`is required.
`sending signals to servos within the flight control system is
`The microcontroller 130 also communicates through a
`illustrated. The process 400 begins at a start state 402 and
`software-generated I'C bus with a temperature sensor 160
`then moves to a state 404 wherein signal properties corre-
`that provides temperature compensation for the accelerom-
`sponding to level flight for the aircraft are stored to the serial
`eter 140 and other sensing electronics. In one embodiment, 55 memory 165 within the flight control system 100. The
`process 404 is normally activated by pressing the zero
`the temperature sensor is a National Semiconductor (Santa
`switch 150 in order to indicate that the current settings for
`Clara, Calif.) Model LM75 temperature sensor.
`Also connected to the microcontroller 130 are a pair of
`the aircraft correspond to level flight. The current settings
`serial memory circuits 165A,B that can store flight infor-
`from the accelerometer are then stored to a memory in the
`mation during the flight or store pitch and yaw data for 60 microcontroller. The aircraft is then launched from the
`ground and, at the state 410, signals are received from the
`future maneuvers. As will be discussed with regard to FIG.
`3, the microcontroller 130 buffers incoming pulse-width
`transmitter 20. The process 400 then moves to a state 415
`modulated signals from the transmitter in order to present
`wherein the current yaw and pitch of the aircraft are captured
`by the microcontroller 130 from the accelerometer 140.
`the signals to the servos in a parallel manner, instead of
`serially. In one embodiment, the serial memory is an Atmel 65 Once the yaw and pitch have been captured by the micro-
`controller 130, and any signals corresponding to flight
`(San Jose, Calif.) Model AT25256, a 256K bit memory
`requests have been received from the transmitter 20, the
`device.
`
`

`

`US 7,219,861 B1
`
`20
`
`8
`7
`determination is made at the decision state 512 that the flight
`process 400 moves to a state 420 wherein all of the signals
`storage mode has not been requested, the process 430 moves
`can be stored to one of the serial memories 165A,B.
`to a decision state 514 to determine whether preprogrammed
`Once the signals have been stored to a memory at the state
`420, the process 400 moves to a decision state 425 wherein
`flight has been requested. Such preprogrammed flight might
`a determination is made whether the signals coming from 5 be, for example, when the pilot wishes to fly the plane in a
`the transmitter 20 need to be modified before being sent to
`preprogrammed configuration, such as a circle, ellipse or
`the servos. This decision process is normally undertaken by
`oval pattern. If a determination is made that preprogrammed
`flight has not been requested, the process 430 moves to a
`instructions within, or communicating with, the microcon-
`troller 130. For example, software instructions and algo-
`state 520 wherein the current flight commands for the
`rithms for analyzing the accelerometer signals and transmit- l o aircraft are stored to registers within the flight control
`system 100. The process 430 then executes the stored flight
`ter signals are preferably stored in the PROM of the
`microcontroller.
`commands by sending them to the appropriate servos at a
`A determination to modify the pulse-width of the signals
`state 522. The process then terminates at an end state 530.
`from the transmitter 20 is based on the requested servo
`If a determination had been made at the decision state 504
`positions from the transmitter 20, along with the data input 1s that no system intervention was requested, the process 430
`from the accelerometer 140. For example, if the data coming
`moves to a state 532 wherein the signals transmitted by the
`from the transmitter indicates a sharp, diving right turn, the
`pilot to the aircraft are stored to registers within the flight
`control system 100. The process 430 then moves to the state
`microprocessor may determine based on the yaw and pitch
`522 to execute the servo commands.
`from the accelerometer that such a maneuver might lead to
`If a determination had been made at the decision state 506
`unstable flight or an aircraft crash.
`If a determination is made at the decision state 425 that
`that an emergency mode was requested by the pilot, the
`process 430 moves to a state 534 wherein the difference
`signal modifications are needed prior to transmitting the
`signals to the servos, the process 400 moves to a process
`between the current pitch and roll of the aircraft and a zero
`state 430 wherein the signals are modified. The process of
`setting are calculated. As is known, the zero setting would
`modifying signals is described more specifically in FIG. 5. 25 correspond to straight and level flight parameters. The
`Once the signals have beenmodified at the process state 430,
`process 430 then moves to a state 536 wherein a corrective
`the modified signals are stored to the serial memory 165A,B
`servo command is calculated in order to return the aircraft to
`at a state 435. The process 400 then moves to a state 437
`a zero (level flight) position. The process 430 then moves to
`the state 520 to store those calculated flight commands to
`wherein the leading edges of all the signals are aligned. The
`process 400 then moves to a state 440 wherein all of the 30 registers within the flight control system 100.
`If a determination was made at the decision state 508 that
`aligned signals are transmitted to the servos and any other
`a flight assist mode had been requested, the process 430
`aircraft flight control system. Thus, the modified, aligned
`moves to a flight assist process state 540, as described below
`signals are sent to the servos which thereafter modify the
`in reference to FIG. 6. The process 430 then moves to the
`flight path of the aircraft. The process then ends at an end
`state 450.
`35 state 520 to store the flight assist commands to registers
`Referring to FIG. 5, the process 430 of modifying signals
`within the flight control system 100.
`If a determination was made at the decision state 512 that
`prior to being sent to the aircraft's flight control systems is
`explained. The process 430 begins at a start state 500 and
`the pilot had requested to store flight information, the
`then moves to a state 502 wherein the signals are read from
`process 430 moves to a state 544 wherein flight information
`a memory storage. Once this information has been read, the 40 is stored to a memory within the flight control system 100.
`process 430 moves to a decision state 504 wherein a
`It should be realized that storing flight information to a
`determination is made whether any system intervention has
`memory can be either a one-time event, such as storing the
`been requested by the pilot. System intervention can be
`current position of the aircraft, or can be an on-going process
`requested by, for example, pressing a button on the trans-
`of storing all the roll and pitch settings so that those
`mitter, or otherwise sending a signal to the receiver in the 45 commands can be later entered into a computer system in
`aircraft. In one embodiment, an extra servo channel can be
`order to illustrate the flight path of the aircraft. Once the roll
`used to signal the system by introducing preselected pulse
`and pitch information has been stored to a memory at the
`state 544, the process 430 moves to the state 520 wherein the
`widths. If system intervention has been requested, the pro-
`cess 430 moves to a decision state 506 in order to determine
`transmitted signals from the pilot are stored to registers and
`whether the type of intervention requested was an emer- 50 thereafter executed by the servos.
`If a determination was made at the decision state 514 that
`gency mode. Such an emergency mode might be requested
`when the pilot can no longer control the aircraft. If a
`the pilot had requested a preprogrammed flight pattern, the
`determination is made at the decision state 506 that an
`process 430 moves to a state 546 wherein a stored flight plan
`emergency mode has not been requested, the process 430
`is retrieved from a memory within the flight control system.
`moves to a decision state 508 in order to determine whether 55 Such a stored flight path might include acrobatic flight
`a flight assist mode has been requested. As described above,
`commands or any other preprogrammed pattern to be flown
`by the aircraft. The process 430 then moves to a state 520
`a flight assist mode is used by the p