US2004460A - Radio steering control - Google Patents

Description

June 11, 1935. 1 BROCKSTEDT- 2,004,460

RADIO STEERING CONTROL Original Filed Au 28. 1930 INVENTOR fit l tages "f md a 7 V v In the use of vibrating reeds for special purv r I Patented June 11, i935 UNIT D STATES .aAnIo s'rnnanvc coNTitoi. Theophile E. Brockstedt, San Francisco, Calif.,

assignor 'to Washingtonlnstitute a corp'orationof Delaware August 28, 1930, Serial Renewed April" 17, 1935 ogy, Inc.,

Application This'inventlon relates to signal apparatus designed to accomplish the automatic steering of marine v'emels and airplanes by radio control and this specification is in part a continuation of an I application entitled Radio signal apparatus and methods, Serial No. 151,915, Filed: Dec.1, 1926, Patent No. 1,865,826.

An object of the 'strument arranged for operation with the double modulation type directive radio beacon, described in the above identified patent and also described in another copending application, Serial 478,497, entitled Method of, and apparatus for, radiodyna-mic steering control 'of even date with this application,and inwhich rument a plurality of mechanically tuned elements equipped with improved air vanes are arranged to make a positive jnon-vibrating electrical contact for the control of steering mechanism under particular operating conditions of the above mentioned instrument; the said instrument being also provided with means for indicating its operating characteristics underv various conditions to assure facility and convenience in use. i

Another object of the invention is to provide a selective relay arrangedto make a non-vibrating electrical contact by means of vibrating (reeds. I A still further object of the invention is to provide an air vane adapted for use on vibrating elements to develop unbalanced dynamic forces, and a to further provide a movably supported member having an axis of rotation, and to which member .the dynamic forces developed by the air vanes, and the .centrifugal forces developed by the ele-' ments in vibration, ful torque around .the axis-of rotation of said member.

Another object of the invention is to describe methods for translating constrained mechanical vibrations into continuous and also differential torques of constant and also variable magnitudes which may be employed for actuating various types of instruments and apparatus.

Other objects of the invention will be made ap- 45 parent inthe course of. description.

A problem in the prior art has been the vibrating contact made by a vibrating reed.

I have devised means to eliminate the vibratcontact and yet retain the selective advanposes, some damping may be required, and this is readily accomplished by the use of common forms of alr'vanes n xed on the free ends of the invention is to provide an in-.

are applied to produce a useto facilitate explanation of of a vibrating reedas shown in Figs. 3;

of Technol- 1 No; 478,498 v reeds. In operation these reeds with their air dampers are wasteful of energy in two respects.- The centrifugal force developed by, the reed in vibration is lost and the resistance of the air overcome by the movement of the damper vane is energy consumed and lost. In Figs. 3, 4, and 5 I illustrate a method of producing'and utilizing this otherwise wasted energy for useful purposes.

Fig. 1 in the drawing is a representation of a radio receiving device.

Fig. 2 illustrates the characteristics of the signals and thespatial arrangement of the zones of maximum amplitude of the directional 'sig-' nals, and also the zones of equal signal intensity of a double modulation. directive radio range 15 beacon.

Fig. 3 is a side view of a selective non-vibrating contact relay. J j

Fig. 4 is an illustration ofthe dynamic forces developed by areed in vibration when having differently shaped air vanes attached atits free end and also showing how these forces are combined and applied to a cantilever to produce a useful torqueat its axis of rotation.

Fig. 5 is a projection of a selective diflerential relay embodying some of the features of this invention in an instrument for automatically controlling the steering mechanism of vessels in accordance with the signals received from a particular radio beacon at a given time. A pair of .30 reeds 'are provided for each beacon and several beacons are provided for in the apparatus.

Fig. 1 shows a radio receiver at l comprising a tunable circuit at 2 coupled to the antenna 3. and a switch "at l to tune the circuit 2. A trans- 85 former 5 is arranged to pass the audio frequency output of the receiverto the electro-magnetic unit 6 shown in Fig. 5. 4

Fig. 2 illustrates a directional radio range beacon in which a pair 'ofdirectional antennas ll 40 and I! are arranged at an angle to one another Qi'or radiating waves modulated withbarticular and 85 cycles respectively theinvention. The

frequencies such as 65 equislgnal zones A, B, C, D, as definite courses, rangea orarbitrary lines of reference. However, since the functioning of the i apparatus may appear complex in some particulars, an understanding of the mode of operation of the system willbe aided ,byconsiderlng.

movements of the illustrated vessels more particularly with respect to or proximity of the vessels, to the one or the other of the zones of maximum signalintensity, rather than to consider the movements'oi' the maybe thought of the approach toward,

as of secondary importance.

60 forces' are effective 70 of rotation 42.

. bitrary lines of reference. The apparatus herein described is not limited .to operationon the equisignal zones, and these zones are here considered The description will be more'readily understood if it is carried in mind that the course designator'66 associated with the panel 61, Fig. 5 is always in the position shown in the drawing when the zone of maximum 65 cycle signal intensity lies on the right-hand J side of the vessel, and this holds good on any heading of the vessel whether steering toward or away from the beacon. The course designator 66 is changed over to its second position only when the maximum 85 cycle signal zone lies on the right-hand side of the vessel when heading on a given course toward or away from the beacon.

Fig. 3 is a selective tuned reed or'resonance relay constructed in accordance with my invention to eliminate the vibrating contacts common to such instruments and is comprised of a lever 22 pivotally fulcrumed at 23 to, a supporting frame 24. A tuned reed 40, having an unbal- 25 anced air vane 31 fastened to its free end, is

attached at its fixed end to one arm of the lever 22. The other arm of the lever 22 has attached thereon a spring 21 carrying a contact button 28. An adjustable contact 29 is arranged ad- 30 jacent the button 29 to make a solid contact therewithwhen the reed 40 is in vibration and the aerodynamic force developed by the unbalanced air vane 31 causes the movably supported member 22 to move from its initial position or initial position of equilibrium as indicated by the dotted line 30, to its contact making position shown bythe line 31. A tension spring 32 is arranged between the lever 22 and the frame 24 to assist in restoring the movable member 22 to its initial position against the stop-rest 33 in which position of the member 22 the contact between 28 and 29 is broken. Due to the bending of the spring 21 the button 26 exerts a rub bing motionon the face of the contact 29 thereby tending to keep the contact surfaces clean and of low resistance in the secondary'circuit 34. One arm of the lever 22 constitutes the armature of the electromagnet 35 in the'primary circuit 36.

Fig. 4 illustrates diagrammatically the dynamic forces developed by a reed 49 having differently shaped vanes fixed to its. free end, and which forces are utilized in this invention. Differently shaped air vanes are shown at 31, 38 and These vanes are fixed to the reeds 40 which form one side of the right-angled cantilevers M, Mn, and 4 I0 which are arranged to rotate around an axis of rotation 42. The arrows in the drawing show the direction in which the developed when the reeds 40 are in a state of .vibration. Considering first the vane 31, when a reed is in a state of vibration there is a centrifugal force developed which acts in the direction indicated by the arrow (0), or parallel the length of the reed 49, or in other words, in a line parallel to the line of position of equilibrium, and this force (a) exerts a tension at the free end of the cantilever 4| to produce an effective and continuous torque around the axis The vane shown at 31 is a semispherical cup in common use on anemometers or wind speed indicators. y when the reed 40 is in vibration and the vane 31 attached thereto is beating the air in two directions, the air offers 7 a greater resistance to the concave side ktthan to the convex side of the cup thus producing an unbalanced force in the direction of the arrow 1), or tangent to the curvilinear motion of translation of the vane around the axis of rotation 42. The resultant force of the two applied forces a and b, or the turning moment of the cantilever 4|, is indicated by the arrow 31ab. At 38 is shown a balanced vane which beats against the same air resistance in both directions of its travel when the reed 40, to which it is attached, is in vibration. But owing to the fact that this vane 38 presents two working faces 1 and m, or inclined planes, to the resisting medium, an aerodynamic force is developed in the direction of the arrow d, or parallel to the length of the reed 40, and thus augments the centrifugal force 0, the two forces tending to move the cantilever 4m in the direction 380d. To utilize the three dynamic forces just explained I have combined the working faces-of the vanes 31 and 38 in the improved vane shown at 39, 3911,11, and 1', and taken in combination with the reeds 40 and the cantilever 0, having an axis of rotation at '42, represents a novel feature of my invention. The vane 39 presents three working faces is, l, and m to the resisting medium when the reed 49 is in vibration. The vane 39 is preferably hollow and closed on all sides and working faces except at k which is left open and produces the force (b) first considered in connection with the vane 31 and now identified by the arrows e and a in connection with vanes 39 and 39p. When the two faces I andm, 39, are alternately driven against the air by the reed 40, the vane 39 exerts a tension in the direction indicated at ,f, or parallel to the length of the reed, and k which causes a resistance to the movement of the reed 49 in only one direction of its travel, produces an unbalanced force in the direction e,'or in one direction tangentially to the are described by the free end of the reed 40. It will thus be obvious that the forces developed by the vane 39 augmentedand the surfaces of the vanes will be streamlined I .where low resistance is desired, and other advantages are to be gained thereby. I

The vanes 39 and 39p, also shownin 5 are identical in construction in every particular but one. Since all the vibrating reeds in my apparatus are tuned to different frequencies, the vanes must also be differently tuned as to size, shape, or weight to conform to the frequency at which they are designed to operate when attached to their respective reeds and thus develop resultant forces of the same magnitude as all the other reeds and vanes in the apparatus. The value 39p develops aresultant force of the same magnitude as that developed by the vane 39 when thereeds 40 are vibrating with equal amplitude,

but the resultants of the forces developed by the of operation of the instrument shown in Fig. 5.

If the'two reeds on the: cantilever 4H0 are vitensities of the signals detected by the The combined structure shown the featuresof the mally rests on the insulation being provided for the positions of the contact strips 49-58 under the The relative positions of the brating with equal amplitude, the forces developed by the reeds and their vanes are equal and opposite and the cantilever cannot rotate on its axis 42. Should the vibratory amplitude of one reed increase while that of the opposite reed is decreased proportionately, the forces acting on the cantilever would become unbalanced and rotation would ensue in one direction or the other as indicated at '38efg and 381m. At 39r and 39q are two views of the new air vane, the shape of which is difficult to describe accurately.

The embodiment of the invention illustrated in Fig. comprises a pair of brackets 44 upon which the pivot spindle 42, supporting the cantilever movement 4 0, ispivotally mounted, Two levers 8-8 constructed in accordance with my invention are pivotally mounted at 9, on the right-angled cantilever movement He. The levers 8-8 havea plurality of reeds 48 mounted on the short arms -|'3, all of said reeds having a diiferent period of vibration. One pairiof the reeds mounted on opposite sides of the movably supported member 0 are shown as having a tuned frequency of 85 cycles and 65 cycles respectively for purposes of explanation in this description. Each of the reeds 48 has an unbalanced air vane at 39, and each of said vanes is designed to function efliciently at the frequency to which its respective supporting reed is mechanically tuned. by the reeds 48, the levers 8-8, the frame 4|0, and the pivot spindle 42, constitutes the balanced right-angled cantilever movement diagrammatically illustrated at Mo, Fig. 4.

To the pivot spindle 42 is attached a spiral spring 45 for the purpose of maintaining and otherwise restoring. the movement 0 to its normal position shown in the drawing when not actuated by unbalanced forces developed by the reeds 48 and their vanes 39. which actuate the reeds 48 are transmitted from the electro-magnetic unit '6 to the long arms of the levers 8 by means of the armature rod 1, the pulsating currents energizing the unit 6 being derived from the receiver Fig. 1, through the transformer 5. The pivot spindle 42 carries an arm 46 which carries a contact roller 41 which functions as a non-vibrating contact actuated by vibrating reeds, and constitutes one of invention described in connection with the structure shown in Fig. 3. Arranged under the roller insulating material 48 separating two metal contact strips 49 and 58 which are operatively arranged on a movable bar 5|. The roller 41 norrelay movement 4|o is acted upon by unbalanced forces, the arm 46 causes the roller 41 to make contact with one or the other of the contact strips 49-58 in accordance with the relative inreceiver I, Fig. 1. 'The movable bar 5| forms a rack which is engaged by a pinion 52 which is operated by the thumbscrew 53, the thumbscrew 53 purpose of adjusting the contact roller 41. contacts 89-58, under the contact-roller 41, with respect to the operating positions of the movable member 4|o and its contact making arm 46, are indicated on the dial 15. A dial pointer 54 is pivotaily connectedat 55 to the movable bar 5| for the purpose of indicating on the dial '15 the differential operating relation between the fixed at its free end as shown The pulsations The wire 18 leading to 41 is shown a piece of 48, but when thethe gyro-pilot system is not a vention, its mechanism has not been shown in position by the guide 59. The reason for employing a movable fulcrum 58 working in a slot 51 is to allow a reversal in the relative movements of the pointer 54 and the bar 5| When the fulcrum 58 is at the bottom of the slot 51 and below the pivot support 55 the pointer 54 will move in the same direction as the bar 5|. But when the fulcrum 58 is at'the top of the slot 51 and above the pivot support 55, the pointer 54 will move in av direction opposite to that of the bar 5|. This reversal in the relative movements of the pointer 54 and the bar 5| is necessary under certain operating conditions of the apparatus. The movable fulcrum 58 is connected by a rack 68 with a gear 6|, and which gear engages a rack 62 on connecting rod 63. The rod 63, which is also operatively connected to the relay reversing switch 65, forms another rack 64 which is engaged by a manually operated gear and course designator 66. The panel61 with which the dial pointer or course designator 66 is associated is designed to identify the various radio ducing equisignal zones fixed in azimuth. The dial shown at 15 indicates the number of degrees or angular distance that a vessel is maintaining a course to the right or left of a particular course or equisignal zone identified on the panel 61, taking alsointo account the fact that the vessel is proceeding to or from the beacon. The contact segments 49-58 are connected by circuit wires 68 and 69 to the relay reversing switch 85 and then by circuit wires 1| and 12 to the primary relays on the relay panel 13 and from which panel the steering motor of the vessel is controlled through the circuit wires 14.

movable contacts 49-58 and the other movable double modulation type of directive radio beacon arranged for pro-' relay panel 13 is neutral to both circuits 68 and 69.. The function of the reversing switch is to reverse the order of actuation of the primary relays on the panel 13 which are actuated through the circuits 68 and 68 by the closing of 'the contacts 49 or 58 by the contact roller 41. If now the gear 66 be turned clockwise in direction, the bar 63 will be moved to the right thus also operating the switch 65 and reversing the circuit arrangement between contacts 49-58 and the two relays connected to wires 1I-12. The relay panel 13 is a conventionally arranged panel in common'use with a well known type of automatic pilot steering mechanism for ships and which is controlled by the gyroscopic compass. The roller 41 in my apparatus takes the place of the repeater motor contact roller in the gyropilot system above mentioned 49-58 in my apparatus take contact .rings in the gyro-pilot the place of the system, but since part of this inthe drawing beyond the relay panel connections 14.

and the contacts 'Fig. 2, and designated by The pair of reeds designated as having periods of 85 cycles and 65 cycles, respectively, are mounted in opposed operating relation in the differential relay Fig. 5, and are tuned to the modulation frequencies of a particular beacon in a system employing several of such beacons. When the audio frequency output of the receiver l energizes the electro-magnetic unit 6 through the transformer 5, the armature rod 1 actuates the levers 8, and the 85 cycle and 65 cycle reeds carrying the air vanes 35 are set in vibration. If a vessel equipped with this apparatus is proceeding toward the beacon 'on the equisignal zone or radio course A, as illustrated by the vessel It, the dial pointer 56 on the panel 6'5, the instrument will function in the following manner. If for example the vessel Ill remains exactly on the equisignal zone'or course A, the 65 and 85 cycle reeds will vibrate with equal amplitudes and as heretofore explained, their tensions on the cantilever ilo will be of equal magnitude and in opposite directions, while the contact roller ll will remain upon the insulation is and the relays on the relay panel 13 will not be actuated. If the vessel should move to the left of the designated course as illustrated at H, Fig. 2, the vessel would be moving toward the side of the equislgnal zone where the 85 cycle signal strength predominates and with the result that the 85 cycle reed will increase its vibratory amplitude, while the 65 cycle reed will proportionately decrease its amplitude, in consequence of which the roller i? would be moved on to the contact segment 50. The .circuit arrangement between the contacts tiland the relays on the panel I3 is such, with the switch 85 in its present position, that when the roller M makes. contact with the contact 50, the rudder of the vessel is automatically turned to the right or in a direction opposite to the movement of the roller 47. The rudder in this position will restore the vessel to its designated course on the equisignal zone, and when on the equisignal zone, the 85 and 65 cycle reeds will again be vibrating with equal amplitude and the retractile spring will assist in restoring the roller 51 to its initial posidegrees t .while proceeding away from the beacon, as illustion on the insulation 48. If the vessel moves to the right of the course as roller 61 will make contact with d9 due to the tension of the 65 cycle reed which increases its amplitude when the vessel moves to the right of the equisignal zone. With the circuit 69-79 closed, the rudder moves to the left or opposite to the movement of the roller contact M and the vessel is again'restored to its designated course where the intensity, the reeds vibrate with equal amplitude, and the roller 41 is restored to its initial position on the insulation it. It will thus be obvious that the selective differential control apparatus steers the vessel automatically by the directive radio beacon signals If it should be desired to maintain a course 10 ithe right of the equisignal zone C, and

tr'ated at I5, the thumbscrew 53, which is pro- .vided for the purpose of setting courses at different angular'distances around the beacon, will be turned to the left or counterclockwise, thus moving the contact support 5! to the right thereby bringing the contact 50 under the roller M, and the dial pointer or angular distance indicator 5% will have moved 10 degrees tothe right, thereby indicating the course which will be automatically maintained. The course designator 66 is in the I illustrated at 12, the

beacon signals are received with equal correct position as shown in the drawing for this heading of the vessel since the maximum 65 cycle signal lies on.the right-hand side of the vessel 15 when heading away from the beacon. If, for example, the vessel were made to steer an opposite course toward the beacon on course C, the cycle'maximum signal zone would then lie on the right-hand side of the vessel, and the course designator 66 'would have to be changed over in order to designate To beacon, Course C on the panel Bl to permit proper functioning of the steering control apparatus. As heretofore explained, the contact roller 4'! when resting on the contact 50 closes the circuit 68-48 and causes the rudder to be turned to the right. With proper adjustment of the apparatus the vessel will maintain a course 10 degrees to the right of the equisignal zone C. It will be understood that the degree of movement of the rudder is purposely limited; and the course will be automatically altered or corrected only a small amount at a time by means and methods well known and understood in the art. At 10 degrees to the right of the equisignal zone C the 65 cycle reed will have suificiently increased its vibratory amplitude to move the roller 4'! to the insulation 68 and in which position the rudder will be automatically restored to its neutral position by the relays on the relay panel I3. Any movement of the roller contact to the right or left will be met by the rudder moving in the opposite direction and restoring the vessel to its designated course.

If now, for example, the vessel at I6 is made to steer a course away from the beacon, on equisignal zone B, it will be found that the relative positions of the differently characterized zones of maximum signal intensity are transposed with respect to the heading of the vessel, that is to say, where formerly the 65 cycle maximum signal lay on the right-hand side of the vessel, the 85 cycle maximum signal now lies on the right-hand side of the vessel. This ambiguous relation of the transmitted signals with respect to the headings of a vessel on different beacon courses and in different directions on the courses, to or from the beacon, has been provided for by means of the change-over mechanism shown at 56 which designates the proper setting of the instrument for steering a course to or from the beacon, by the reversing switch 85, and by the movable fulcrum 58 working in the slot 57 for reversing the relatitve movement of the pointer 55. This reversal of the order of actuation of the-relays on the panel 13 by the circuit closing contacts 49, 56, and 51 can be carried out by other means such as would consist of a simple mechanical move ment for reversing the position of the contacts 49 and 50 and eliminating the reversing switch '55, and it is to be understood that such modifications suggesting themselves to those skilled in the art are within the scope of my invention.

Considering again the case in which the vessel I6 is heading away from the beacon on courseB, if the course designator 66 is not changed over to indicate From beacon, Course B, on the panel 61, the automatic steering apparatus will cause the vessel to execute a 180. degree turn from its course away from the beacon and will thereafter steer itself back toward the beacon as shown at H. When the course designator 66 is moved to the right, the connecting rod 63 operates the reversing switch 65 and. also the gear 6| whichmoves the fulcrum '58 to the top the. slot 51 in the position of the fulcrum 58 in the slot 51 reverses the same in practice.

the movement of the pointer 54 relative to the movement of the rack 5|.

It will be apparent that this embodiment of the I invention requires no technical knowledge on the part of'the navigator for an intelligent use of The relative positions of the principal radio courses are known to the navigatorand the ambiguous relation of the transmitted signals on the various courses is provided for in the apparatus.

It is to be understood that the invention is not limited to any specific construction but might be embodied in various forms without departing from the spirit of the invention or the scope of the appended claims.

Having described my invention what I now claim is:

1. In a navigational apparatus adapted for cooperation with a source of differently characterized signals to delimit definite courses, the combination including a receiving device, a selective differential relay connected to said receiving device and arranged to respond to the relative magnitudes of said signals, a contact maker associated with said relay, a set of adjustable contacts ar ranged adjacent said contact maker, means to adjust the operating relation between said adjustable contacts and said contact maker, and automatic steering apparatus control circuits arranged with said contacts for differential actuati'on thereby.-

2. In apparatusaccording to, claim 1, in which an indicating means is operatively arranged to indicate the degree of adjustment of the adjustable contacts relative to the position of the contact maker.

3. In apparatus according to claim I, in which a course designator is operatively arranged with the steering apparatus control circuits for designating and determining the proper operating adjustment of the relay control apparatus for operation on a given course.

4. In apparatus according to claim 1, in which a course designator; a means for indicating the degree of adjustment of the adjustable contacts, together with means for reversing the order of movement of said indicating means; and means for reversing the order of control of the steering apparatus control circuits, are operatively associated for simultaneous adjustment of the relay control apparatus for operation on a given course. 5. In navigational apparatus adapted for use with a source of differently characterized signals producing equisignal zones fixed in azimuth, the combination comprising automatic steering control apparatus simultaneously and differentially responsive to said signals and operatively arranged with steering mechanism on a movable body for causing the latter to maintain a predetermined course relative to a givenequisignal zone, course setting means to make said steering control apparatus respond to predetermined relative magnitudes of said signals to cause said movable body to maintain a predetermined course at a predetermined angular distance tothe right or left of said equisignal zone, and means to indicate and determine the angular distance of a given course to the right or left of said equisignal zone.

6. In apparatus as defined in claim 5, in which means is associated with-the steering control apparatus to identify the various equisignal zones and designate the proper adjustment of said control apparatus for maintaining a given course on a given equisignal zone in a given direction relaratus connected to said work circuits.

tive to the direction of the source of signals pro ducing said zones. Y

7. In apparatus as defined in claim 5, in which reversing means for the angular distance indicating means; means for reversing the order of the operating control of the steering control apparatus; and designating means, are operatively associated with the steeringrcontrol apparatus.

8. In automatic steering control apparatus, a receiver of differently characterized simultaneous signals, an electro-mechanical resonance differential control device operable responsive to the frequencies and relative magnitudes of said signals, and automatic steering apparatus control circuits operatively associated with said control device for differential actuation thereby.

9. A mechanically selective differential device operative in response to the relative magnitudes of a plurality of simultaneously applied actuating forces, consisting of a movably supported mem her, a plurality-of vibratile elements arranged in opposed operating relation with said member for causing the latter to move differentially, means for causing said elements to vibrate, and apparatus operatively associated with said member for actuation thereby.

10. A selective differential control device comprising a movably supported member, a plurality of differently tuned vibratile elements arranged in opposed operating relation with said member and adapted for developing centrifugal forces which actuate said member, means to cause said elements to vibrate, and desired apparatus operatively associated with said member for actuation thereby.

11. The combination comprising a movablyv supported member, a plurality of vibratile elements arranged in opposed relation integrally with said member to cause the latter to move differentially when the opposed actuating forces developed by said elements are unbalanced, means to cause said elements to vibrate, and work circuits operatively associated with said member for differential actuation thereby.

12. The combination comprising a movably supported member, a plurality of differently tuned vibratile elements providedwith unbalanced vanes operatively arranged in opposed relation with said member ferential movement thereof, means to cause said elements to vibrate, and apparatus associated to'effect a resultant difing frequencies corresponding to the frequency of vibration of said reeds, contact making means associated with said member and arranged to make contact differentially with a plurality of contacts adjacent said contact making means a plurality of work circuits connected to said contacts and said contact making means, and appa- 14. A differential device which responds difference in magnitude of a plurality of neously received signals, comprising a of vibratile elements for producing to the simultaplurality dynamic forces acting in opposition on a balanced rotary movement, means to actuate said elements selectively, circuit actuating means co-operating with said rotary movement for actuating a set of control circuits, and apparatus connected to said control circuits to be actuated thereby.

15. In combination, a craft equipped with suitable automatic steering apparatus, control means mechanically selective and differentially responsive to a plurality of received signals and operatively associated with said steering apparatus, and course setting means associated with said responsive control means for the purpose of regulating the function of said control means whereby the steering apparatus is made to respond to desired difierences in strength of said received signals to cause said craft to automatically maintain selected courses ranging in different desired directions.

16. In automatic steering apparatus for a movable body, comprising means for receiving and detecting radio signals, control means mechanically selective and differentially responsive to the distinctive modulation components of said signals, course indicating means associated with said control means, and steering mechanism for said body controlled by said control means.

17. Steering apparatus for a movable body, comprising a radio receiver for supplying two simultaneous currents of difierent frequencies and having relative magnitudes which'vary in accordance with the course of the body, a mechanical resonance difierential control device responsive to the frequencies and magnitudes of said currents, and steering mechanisms for said body controlled by said control device.

18. A selective relay, comprising, a movably supported member, vibratile aerodynamic means arranged with said member for causing the latter to move, means for causing said vibratile means to vibrate, and apparatus operatively associated with said member for actuation thereby.

19. A selective relay, comprising a movably supported member, a tuned vibratile element having an unbalanced vane operatively arranged with said member for causing the latter to move, primary means for causing said element and vane to vibrate, and secondary means associated with said member for actuation thereby.

20. The combination including a plurality of vibratile elements for producing dynamic forces acting in opposition on a movable member, means for actuating said elements selectively, means cooperating with said movable member for differentially actuating a plurality of control circuits, and means for altering and indicating the relative operating adjustment member and said control circuits.

THEOPHILE E. BROCKSTEDT.

between said movable-

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