United States Patent [191
`Smith, III et al.
`
`[11]
`[45]
`
`Patent Number:
`Date of Patent:
`
`5,043,646
`Aug. 27, 1991
`
`[54] REMOTE CONTROL DIRECTION
`SELECTING SYSTEM
`[75] Inventors: Jay Smith, III; Daniel J. Schmieder,
`both of Los Angelgs’ Calif‘
`[73] Assignee: Smith Engineering, Culver City,
`Calif.
`
`[21]‘ Appl' No" 517368
`[22] Filed:
`May 1, 1990
`[51] Int C15
`H04Q 7/02_ 605D 3/10
`[52] Us‘ Ci """""""""""" "
`318/’581_ 318/16
`'
`'
`' """""""""""""""""""" "
`’ 318 587’
`[58] Field of Search
`318/16 580 583 581'
`31g /58 i 587’ 588’
`’
`’
`
`"""""""" "
`
`[56]
`
`References Cited
`Us PATENT DOCUMENTS
`
`Rtlfiilet a1. ............................ .. 318/12
`3319272
`$33422 [£1951 ‘gcrthzgilgt a1‘
`Mug-?gs
`2’7O5’793 4/1955 Litchford
`'_‘_'"é'18/581 X
`2,745,614 5/1956 Bennett et a1.
`..... .. 244/184
`2,826,380 3/1958 Ketchledge ..... ..
`244/184
`2,866,930 12/1958 Russell ................................ .. 318/16
`
`Primary Examiner—Bentsu Ro
`Attorney, Agent, or Firm-Price, Gess & Ubell
`[57]
`ABSTRACT
`A remote control transmitter/receiver system wherein
`an absolute direction command may be issued by the
`transmitter and acted upon by the receiver. The trans
`mitter and receiver both include a common reference
`direction so that an absolute direction command (i.e.,
`relative to the common reference direction) may be
`issued and acted upon. In a preferred embodiment, the
`transmitter operates in accordance with an internal
`compass signal so that an absolute direction command
`relative to magnetic North can be generated by the
`transmitter. The receiver also functions in accordance
`with an internal compass signal so that an absolute di
`rection command transmitted to the receiver can be
`effected. The transmitter and receiver may be micro
`processor controlled, and the internal compass signal
`may be generated with an electronic ?ux gate Compass‘
`The invention may be used in place of the conventional
`remote control systems that are used with hand-held
`Mummers and hobby vehlcles
`
`9 Claims, 4 Drawing Sheets
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`Aug. 27, 1991
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`5,043,646
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`REMOTE CONTROL DIRECTION SELECTING
`SYSTEM
`
`15
`
`25
`
`30
`
`BACKGROUND OF THE INVENTION
`1. Field of the Invention
`The present invention relates generally to remote
`control systems where a user selects and transmits a
`direction control signal from a remote control transmit
`ter to a remotely controlled device. More particularly,
`the present invention relates to an improved remote
`control system where the user may select a desired
`direction relative to an external reference direction
`without considering the orientation of the remote con
`trol transmitter or the remotely controlled device rela
`tive to the external reference direction'
`2. Description of the Prior Art
`There are many known varieties of remote control
`systems. Probably the ?rst to come to mind are those
`used with hobby vehicle systems such as remote control
`planes, boats, cars, etc.
`A typical prior art hobby vehicle system consists of a
`remote control transmitter that includes a user-operated
`means for selecting either “left” or “right” and for
`transmitting a direction control signal in response to the
`user selection and 'a remotely controlled vehicle (car,
`boat, plane, etc.) that responds to the transmitted direc
`tion control signal. For example, a radio controlled car
`is comprised of a car that may be commanded to turn
`left or right and a remote control transmitter from
`which the user may select and transmit left or right
`direction control commands. A typical direction select
`ing means consists of a joystick that may be moved
`either left or right relative to the remote control device.
`35
`Ordinarily, the user must continuously hold the joystick
`in the selected direction during the entire time that the
`vehicle is turning and then release the joystick to end
`the turn.
`The prior art remote control systems are burdened by
`the fact that the resulting direction of the vehicle is
`based on factors that are constantly changing relative to
`the user and the remote control transmitter, namely the
`position and direction of the vehicle. Since the position
`and direction of the remotely controlled vehicle are
`constantly varying relative to the user, the resulting
`direction of the vehicle, relative to the user, is also
`constantly varying.
`_
`'
`Given a remote control car, for example, if a user
`selects and transmits a “left” or “right” direction con
`trol signal when the car is travelling radially away from
`the user, the resulting direction of the car, relative to
`the user, will correspond to the transmitted direction
`control signal. More speci?cally, if a “left” command is
`transmitted, the car will travel left relative to its direc
`tion and position and also relative to the user.
`However, if a “left” or “right” direction control
`signal is transmitted to the car when it is travelling
`radially towards the user, the resulting direction of the
`car, relative to the user, is inversely related to the trans
`mitted direction control signal. Under these circum
`stances, if a “left” command is transmitted, the car will
`travel left relative to its direction and position but will
`travel right relative to the user.
`It can be seen from the above description that the
`user with an ordinary radio control system must always
`be conscious of the position of the vehicle and the direc
`tion that it is travelling, both before and during a turn,
`
`45
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`55
`
`65
`
`2
`so that the user can rapidly engage in the mental acro
`batics necessary to steer the vehicle.
`
`SUMMARY OF THE INVENTION
`It is an object of the present invention to provide a
`remote control transmitting device that is capable of
`transmitting a direction control signal that contains
`direction control information relative to an external
`reference direction;
`It is a further object of the present invention to pro
`vide a remotely controlled device that includes a direc
`tion related feature, the direction related feature re
`sponding to a direction control signal that contains
`direction control information relative to an external
`reference direction;
`It is a further object of the present invention to pro
`vide an improved remote control system wherein a
`direction control command takes effect relative to the
`position of a remotely controlled vehicle, but without
`regard to the direction that the vehicle is facing; and
`It is a further object of the present invention to pro
`vide an improved remote control hobby vehicle system
`that includes a remote control vehicle and a remote
`control transmitting device where the user is capable of
`selecting an absolute direction command and the re
`mote control vehicle is capable of responding thereto.
`The present invention achieves the above objects by
`providing a remote control transmitting device that
`comprises a ?rst measuring means for measuring the
`orientation of the remote control transmitting device
`relative to an external reference direction, a second
`direction measuring means for measuring a user
`selected direction relative to the remote control trans
`mitting device, and a processing means for generating a
`direction control signal based on ?rst and second com
`ponent direction signals output by the ?rst and second
`direction measuring means. The present invention fur
`ther includes a remotely controlled device that includes
`a third measuring means for measuring the orientation
`of the remotely controlled device relative to the exter—
`nal reference direction and a means for controlling a
`direction related feature of the remotely controlled
`device based upon- a component signal output by the
`third measuring means and a control signal received
`from a remote control transmitting device.
`The features of the present invention which are be
`lieved to be novel are set forth with particularity in the
`appended claims. The present invention, both as to its
`organization and manner of operation, together with
`further objects and advantages thereof, may best be
`understood by referencing the following description in
`conjunction with the accompanying drawings.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`FIG. 1 a schematic representation of a prior art radio
`control vehicle system where a left or right direction
`control command transmitted by the remote control
`device is effectuated as a left or right direction control
`command relative to the position of the car and the
`direction in which the car is currently facing;
`FIGS. 2a and 2b are schematic representations of a
`radio controlled vehicle system according to the pres
`ent invention wherein a user-selected direction D is
`treated as an absolute direction command, independent
`of the orientation of the remote control transmitting
`device, the vehicle altering the current direction it is
`facing to travel in the selected direction;
`
`

`
`3
`FIG. 3 is a schematic block diagram of a remote
`control transmitting device according to the present
`invention;
`FIG. 4 is a schematic block diagram of a remote
`control receiving device according to the present in
`vention; and
`FIG. 5 is a bit map of a digital command sequence
`transmitted by the remote control transmitting device.
`
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`5,043,646
`4
`single hand-held housing like that schematically shown
`in FIG. 2a.
`The primary purpose of the present invention is to
`allow the user to control the direction ofthe the car 200
`by moving the shaft 26j of the joystick 26 towards any
`desired absolute direction. For clarity, all subsequent
`directions stated in degrees are to be taken relative to
`magnetic North. For example, East will be stated as 90°
`and West will be stated as 270°.
`Ordinarily, a user of the present invention would
`select a desired direction without knowing or even
`being concerned with how the desired direction relates
`to magnetic North. More speci?cally, the user would
`simply select a direction in which he or she wants the
`car to travel as if he or she were standing at the point
`where the car is currently located.
`Referring still to FIG. 3, it can be seen that sine and
`cosine voltages 14, 12 are available as outputs from the
`flux gate compass 10. A suitable flux gate compass is the
`Micronta Automotive Electronic Compass sold by
`Radio Shack, Catalog No. 63-641. A detailed discussion
`of the operational details of the ?ux gate compass will
`be omitted because such devices are well known and
`their internal operation does not constitute a material
`portion of this invention except as herein explained.
`Suf?ce it to say that the magnitude of the voltages
`present on the sine and cosine outputs 14, 12 correspond
`to the sine and cosine of the earth‘s magnetic ?eld, and
`that the data necessary to interpret the orientation of the
`?ux gate compass and the remote control transmitter
`100 is obtained by determining the ratio of the sine and
`cosine voltages. For this purpose, the sine and cosine
`voltages 14, 12 are provided to the microcontroller 24
`via an 8-bit successive approximation A/D converter
`13. As shown in FIG. 3, the A/D converter 13 is com
`prised of two comparators 16, 18. The sine and cosine
`voltages 14, 12 are provided to the noninverting inputs
`of the comparators 16, 18 and an R/2R 8-bit DAC
`ladder circuit 22 provides a variable analog reference
`voltage to the inverting inputs of the comparators. The
`microcontroller is programmed to determine the magni
`tude of the sine and cosine voltage 14, 12 by taking the
`8-bit R/2R DAC 22 through a voltage progression
`while simultaneously monitoring the outputs 17, 19 of
`the two comparators.
`The microcontroller determines the orientation of the
`flux compass by ?rst dividing the absolute value of the
`sine voltage 14 by the absolute value of the cosine volt
`age 12 to obtain a tangent voltage, and by then using the
`tangent voltage as an index into an arctangent look-up
`table of 256 entries ranging from O to 90 degrees. The
`angle found in the arctangent look-up table is then ex
`panded into one of four quadrants by taking into ac
`count the relative signs of the sine and cosine voltages
`14, 12. The resultant angle represents the orientation of
`the remote control transmitter 100 and the flux gate
`compass from between 0 and 359 degrees relative to
`magnetic North.
`The joystick 26 is an eight position 4-microswitch
`joystick. A suitable joystick is produced by Archer
`under the trade name Super-Deluxe Competition Joy
`stick, Catalog No. 270-1703. The orientation of the
`joystick shaft 26j relative to the remote control trans
`mitter 100 is communicated to the microcontroller 24
`via four inputs lines labelled 0°, 90°, 180°, and 270°. The
`four input lines correspond to the joystick’s four micro
`switches and provide a 45-degree resolution in that
`
`60
`
`DESCRIPTION OF THE PREFERRED
`EMBODIMENTS
`The following description is provided to enable any
`person skilled in the art to make and use the invention
`and sets forth the best modes contemplated by the in
`ventor of carrying out his invention. Various modi?ca
`tions, however, will remain readily apparent to those
`skilled in the art, since the generic principles of the
`present invention have been de?ned herein speci?cally
`to provide an improved remote control direction select
`ing system.
`The preferred embodiment of this invention is di
`rected towards a remote control system that includes a
`handheld remote control transmitter 100 and a small
`scale. remotely controlled car 200 (see FIGS. 2a and 2b).
`The remote control transmitter 100 transmits control
`signals in response to various user-manipulated control
`switches. Typical control switches include a forward
`/reverse switch, a “turbo” switch for temporarily in
`creased speed, and a direction control switch such as a
`joystick 26]. The remotely controlled car 200 is typi
`cally controlled with left/right and forward/reverse
`signals that are activated in accordance with control
`signals transmitted by the remote control transmitter.
`In the prior art remote control systems, the user is
`limited to only a left and a right direction control. As
`shown in FIG. 1, a prior art remote control transmitter
`60 might have a joystick shaft 62 that can be moved left
`or right or, alternatively, separate left and right direc
`tion control buttons (not shown). The disadvantage of
`such a remote control transmitter 60 is that a user’s left
`40
`or right selection is effectuated relative to the position
`of the car and the direction (d) that the car is facing
`rather than relative to the user or some external refer
`ence direction. Thus, the user must ?rst mentally con
`sider what direction the car is travelling before select
`ing left or right. Moreover, the user must constantly
`consider the relationship between the direction of the
`car and the selected direction throughout the entire turn
`and must release the joystick shaft 62 as soon as the car
`has turned into the desired direction.
`The present invention offers a remote control system
`that transmits an absolute direction command (relative
`to magnetic north) so that the user can control the car
`without being concerned about the direction that the
`car is travelling prior to or while manipulating the di
`rection controls, without being concerned about the
`orientation of the remote control transmitter 100, and
`without having to release the joystick shaft at the pre
`cise moment that the car has achieved the desired direc
`tion.
`FIG. 3 is a schematic block diagram of a preferred
`remote control transmitter 100 according to the present
`invention. The remote control transmitter is comprised
`of a microcontroller 24 that is provided with inputs
`from three momentary pushbutton control switches 28,
`30, 32, an S-position joystick 26, and a flux gate compass
`10 (via an A/D converter 13). All of the components
`depicted in FIG. 3 ‘would ordinarily be contained in a
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`either a single or two angularly adjacent microswitches
`are closed and communicated to the microcontroller 24.
`As further shown in FIG. 3, the remote control trans
`mitter 100 is also comprised of the following control
`switches: a momentary contact forward control switch
`28, a momentary contact turbo control switch 30, and a
`momentary contact reverse control switch 32. In the
`preferred embodiment, the forward and reverse control
`switches 28, 32 are combined in a single momentary
`rocker switch so that their operation is mutually exclu
`sive. The compass 10 angle is added to the joystick 26
`angle to provide an absolute, North-referenced angle to
`be transmitted.
`The user selects a desired direction (D) with the
`joystick shaft 26j (“selected direction”) while simulta
`neously depressing either the forward 28 or reverse
`switch 32. The absolute direction (“absolute” meaning
`relative to magnetic North) corresponding to the se
`lected direction is obtained by summing the orientation
`of the remote control transmitter 100 relative to mag
`netic north with the orientation of the shaft 26j relative
`to the remote control transmitter 100. For example, if
`the user moves the joystick shaft 26] so that it is oriented
`90° relative to the remote control transmitter 100 while
`holding the remote control transmitter 100 so that‘ it is
`oriented 60° from North, the user has selected an abso
`lute direction of 150'’ relative to North. A direction
`control signal containing information about the absolute
`direction relative to magnetic North can then be pro
`vided to an ordinary radio transmitter 36 via line 34 and
`then transmitted over antenna 38 to the car 200.
`In the preferred embodiment, the direction control
`signal is part of a digital command sequence of four
`bytes (see FIG. 5). Byte l is a ?xed sync byte (AA hex)
`that allows the microcontroller 124 in the car 200 to
`detect the beginning of a new digital command se
`quence. Byte 2 encodes the forward, turbo-forward,
`and reverse commands and also contains a single bit that
`indicates that the joystick handle 26j has been depressed
`to initiate a turn. Byte 3 contains the direction control
`signal as a digitally encoded number that ranges from 0
`to 359 degrees. The direction control signal corre
`sponds to an angle relative to magnetic North, Byte 4 is
`a checksum of bytes 2 and 3, the digital command se
`quence being ignored by the car 200 if it determines that
`the checksum does not match (due to radio interference
`or the like).
`Referring now to FIG. 4, the remote control receiver
`200 is comprised of a microcontroller 124, a flux gate
`compass 110, a radio receiver 136, motor control cir
`cuitry 150, and steering control circuitry 140. The flux
`gate compass 110 is identical to the flux gate compass 10
`used in the radio control transmitter 100. The flux gate
`compass 110 provides sine and cosine voltage outputs
`114, 112 that vary based on the orientation of the com
`pass 110 relative to magnetic North. The sine and cosine
`voltages 114, 112 are provided to microcontroller 124
`via A/D deconverter 113. The operation of A/D con
`verter 113 is identical to that of A/D converter 13,
`earlier described, and its description will therefore be
`omitted.
`The radio receiver 136 receives digital command
`sequences transmitted by the remote control transmitter
`100 via antenna 138. Digital command sequences so
`received are provided by the radio receiver 136 to the
`microcontroller 124 on line 134. Once a command se
`quence has been received by microcontroller 124, and if
`the checksum test passes, then the digital command
`
`6
`sequence is processed. For example, if the car is in mo
`tion, and the appropriate Byte 2 indicates that a joystick
`command has been received, then microcontroller 124
`will read the flux gate compass 110 to determine if a
`turn is required. If a turn is required, microcontroller
`124 will determine which of two possible directions will
`result in the smallest angle of rotation. While the turn is
`in progress, microcontroller 124 will periodically read
`the flux gate compass 110 to determine when the car
`200 has converged to the commanded angle (direction
`control signal) contained in byte 3.
`The steering of the car is accomplished via a steering
`electromagnetic 146 that is controlled by the microcon
`troller 124 via left and right control lines 142, 144 and a
`steering control circuit 140. The steering control circuit
`140 is interfaced to the steering electromagnet 146 via
`lines 145 and 147. The precise operation of the steering
`control circuit 140 is not considered material to the
`present invention, and a detailed description thereof is
`therefore omitted.
`Motion is imparted to the car 200 with an electric
`motor 157 that is controlled by microcontroller 124 in
`accordance with the pertinent portions of the digital
`command sequences. The microcontroller 124 commu
`nicates with a motor control circuit 150 via a “turbo”
`control line 152, an “FWD” control line 154, and a
`“REV” control line 156. The motor control circuit 150
`is connected to the motor 157 via lines 158 and 159.
`The direction of the car 200 can be controlled based
`upon the orientation of the car 200 relative to magnetic
`North and the direction control signal contained in the
`digital control sequence (Byte 3, FIG. 5), because the
`car 200, like remote control transmitter 100, contains a
`?ux gate compass 110 for measuring the orientation of
`the car 200 relative to magnetic North.
`Those skilled in the art will appreciate that various
`adaptations and modi?cations of the just-described pre
`ferred embodiment can be con?gured without depart
`ing from the scope and spirit of the invention. For ex
`ample, the present invention is adaptable to other hobby
`vehicles such as planes and boats. Moreover, the pres
`ent invention is generally applicable to any directional
`device that is remotely controlled. Therefore, it is to be
`understood that, within the scope of the appended
`claims, the invention may be practiced other than as
`speci?cally described herein.
`What is claimed is:
`1. An improved remote control device that includes a
`selecting means for allowing a user to select a user
`desired direction and a means for transmitting a direc
`tion control signal in accordance therewith to control a
`direction related feature of a remotely controlled de
`vice, the improvement comprising:
`a ?rst direction measuring means in the remote con
`trol device for measuring the orientation of the
`remote control device relative to an external refer
`ence direction and for outputting a ?rst component
`signal representative thereof;
`a second direction measuring means in the remote
`control device for measuring the user desired di
`rection relative to the remote control device and
`for outputting a second component signal represen
`tative thereof; and
`a processing means for generating the direction con
`trol signal based on the first component signal and
`the second component signal, the direction control
`signal corresponding to the user desired direction
`relative to the external reference direction
`
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`5,043,646
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`the hand-held control device and for outputting
`a ?rst component direction signal;
`(0) a second direction measuring means for measur
`ing the orientation of the hand-held control de
`vice relative to the external reference direction
`and for outputting a second component direction
`signal;
`(d) processing means for deriving a direction con
`trol signal that corresponds to the desired direc
`tion, the direction control signal being derived
`from the ?rst and second component direction
`signals; and
`(e) transmitter means for transmitting the direction
`control signal; and
`(2) a hobby vehicle including:
`(a) receiver means for receiving the direction con
`trol signal;
`(b) a third direction measuring means for measur
`ing the orientation of the hobby vehicle relative
`to the external reference direction and for out
`putting a third component direction signal;
`(0) control means for outputting a steering signal
`that is proportional to the difference between the
`direction control signal and the third component
`direction signal; and
`(d) steering means for steering the hobby vehicle in
`the desired direction in response to the steering
`signal.
`7. The remote control hobby vehicle system of claim
`6 wherein the selecting means is a joystick.
`8. The remote control hobby vehicle system of claim
`6 wherein the external reference direction is magnetic
`north.
`9. The remote control hobby vehicle system of claim
`6 wherein the selecting means is a joystick; the ?rst
`direction measuring means is comprised of micro
`switches that are activated by the joystick; and the
`second and third direction measuring means are each
`comprised of a flux gate magnorneter.
`*
`It
`)0!
`Ill
`=1!
`
`7
`whereby the user selects the user desired direction
`relative to the external reference direction without
`regard to the orientation of the remote control
`device.
`2. The improved remote control device of claim 1
`where the external reference direction is magnetic
`north.
`3. The improved remote control device of claim 1
`wherein the ?rst direction measuring means is com
`prised of a flux gate magnorneter.
`,
`4. An improved remotely controlled device having a
`direction related feature that is controlled based upon a
`direction control signal received from a remote control
`device, the improvement comprising:
`measuring means in the remotely controlled device
`for measuring the orientation of the remotely con
`trolled device relative to an external reference
`direction and for outputting a component signal
`representative thereof wherein the measuring
`means is comprised of a flux gate magnometer; and
`means for controlling the direction related feature of
`the remotely controlled device based upon the
`direction cc trol signal and the component signal
`whereby the ~"irection related feature is controlled
`in a particular direction relative to the external
`reference direction based upon the direction con
`trol signal.
`5. The improved remotely controlled device of claim
`4 wherein the external reference direction is magnetic
`north.
`6. A remote control hobby vehicle system compris
`ing:
`(1) a hand-held control device including:
`(a) selecting means on the hand-held control device
`for allowing a user to select a desired direction
`relative to an external reference direction;
`(b) a ?rst direction measuring means for measuring
`the orientation of the selecting means relative to
`
`25
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`35
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`45
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`50
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`55
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`60
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`65