Patent GB-728413-A (GB)
Title: Multi-chart course indicating apparatus
Inventor: MURRAY THOMAS BRIAN
IPC: G01C21/22
Filed: 1953-03-03
Abstract: 728,413. Course-recording apparatus. COMMUNICATIONS PATENTS, Ltd. March 3, 1953, No. 5838/53. Class 97 (2). [Also in Group XXXVI] Multi-chart apparatus for indicating the course of a craft which may pass from an area represented on a first chart into an area which is represented on a second chart and which may also be represented on the first chart, comprises supports for separate charts, a separare indicating element for cooperation with each chart, translating means operative under the control of data representing the movement of the craft to bring about relative movement of such elements and their respective charts, computing means controlled by data representing the movement of the craft, and means controlled by the computer and serving to maintain the second indicating element on the boundary of the second chart until the craft moves into the area represented thereon or into that area which is represented on both charts, and thereafter to initiate relative movement of the second chart and its indicating element so as to indicate movement of the craft into and within the area represented on the second chart. In the arrangement shown in Fig. 1, the two areas are represented on charts 14, 16 respectively and North-South movement of the cratt is indicated by movement of pens 20, 46 along lead screws 21, 40 while East-West movements of the craft are recorded by movement of these pens as the lead screws 21, 40 are moved parallel to themselves when lead screws 30, 41 are rotated. North-South ground speed signals are applied to terminal 22 and thence to amplifiers 23, 44 which energize motors coupled by gear boxes to the lead screws 21, 40 so that the pens 20, 46 are always at the same latitude as represented on the charts. East-West ground speed signals are applied to terminal 31, which when the craft is in the area represented by chart 14 is connected through spring contact 32a with amplifier 33 which rotates a motor coupled to the horizontal lead screw 30 so that the East-West movement is applied to the pen 20. This motor is also coupled to a cam 39 having a follower 47 which, when the craft has reached a position on the Eastern boundary of the area represented by chart 14, opens contacts 48 to de-energize a relay 32 and move contact 32a to energize an amplifier 45 whereby the lead screw 41 is rotated to apply East-West movement to the pen 46 so that the path of the craft is now recorded on chart 16. The apparatus may be modified so that East-West ground speed signals are always applied to the motor 38 with the result that if the craft returns to the area designated by chart 14 its path thereover will be recorded. The modification of Fig. 2 includes a first course-recording system whereby a pen 20 delineates the path of a craft on a chart 14, this system differing from the corresponding system of Fig. 1 in that both amplifiers 33, 23 are connected through spring contacts 10a, 50b of a relay 50 with the terminals 31, 22 and in that the servomotor 25 is coupled to the wiper of a potentiometer 56. The relay 50 has further spring contacts 50c, 50d, 50e, 50f in the second course-recording system which includes a pen 46 movable over a chart 16 by means of motors 42, 43 to which North-South and East-West ground speed signals are applied via terminals 22, 31 when the course-recording operation on chart 14 has ended. Motor 42 is connected through contact 50e to a switch arm 55 co-operating with contacts 55b, 55a of which contact 55b is connected to the wiper of potentiometer 56 in the first course-recorder. For a period during the recording on chart 14, motor 42 is de-energized by connecting arm 55 with contact 55a. If it appears that the craft is flying towards the East of chart 14, a switch arm 51 is moved into engagement with a contact 51b. This causes energization of motor 43 via contacts 50c, 50d, this motor being coupled to the wiper of a potentiometer 53, to move pen 46 to the left-hand bottom corner of frame 17. A chart 16 representing the area to the East of that depicted by chart 14 is then located in the frame 17. Thereafter switch arm 55 is set to contact 55b so that motor 42 is energized via spring contacts 50e, 50f until the resultant of the anti-phase voltages of the wipers of potentiometer 56, 58 is zero, the latitude of pen 46 on chart 16 then being the same as that of pen 20 on chart 14. When the craft leaves the area depicted on chart 14, cam 49 opens contacts 48 so that relay 50 is de-energized and the spring contacts 50a-50f move to their lower positions. This disconnects the servo-systems of the first course-recorder from terminals 22, 31, disconnects the wipers of potentiometers 56, 58 and connects the second course recorder with the terminals 22, 31 so that course recording now takes place on chart 16. In Fig. 3 (not shown) the two course-recording pens move in accordance with the North-South signals and the charts, mounted on rollers, move in accordance with East-West signals. The motors driving these charts are always connected to the East-West terminal but while the craft is within the area depicted by the first chart the North-South terminal 22 is not connected to the second amplifier so that the second pen does not have a North-South movement. When the craft reaches the Southern boundary of the first chart a cam opens the contacts of a relay to disconnect the amplifier of the first course-recorder and to connect the second course-recorder with the North-South terminal so that courserecording commences on the second chart. Fig. 4 shows apparatus for course-recording on a chart 69 when a craft is within a part, shown as a dotted rectangle, of the area depicted by chart 14. In this form, the vertical and horizontal lead screws 21, 30 are coupled with the wipers 70, 86 of rotary switches having arcuate contacts 72, 73 and 89, 90 separated by gaps 75, 88. The bodies of these switches are manually rotatable so that the gaps 75, 88 can be given positions in the paths of the wipers 70, 86 corresponding to the position of the rectangle in the North-South and East-West dimensions of chart 14 respectively. With the pen 20 to the North of the dotted rectangle, a relay 79 connected at 77 to switch contact 72 is energized while relay 80 connected at 78 to switch contact 73 is de-energized. The servo-system 42, 44 is thus connected through spring contacts 79a to a source of alternating potential 81 and to a potentiometer 82, the wiper of which is coupled to motor 42 so that pen 46 is driven to the top of lead screw 40 and held there. If at the same time, the pen 20 is to the East of the rectangle on chart 14, a relay 92 is energized via switch 88 while relay 91 is unenergized. This energizes servo-system 43, 45 so that pen 46 is moved to the Eastern end of chart 69. When pen 20 is within the rectangle on chart 14, relays 79, 80, 91, 92 are all de-energized and the servo-system 42, 44 and 43, 55 are connected respectively to terminals 22, 31 and the pen 46 delineates on chart 69 the part of the craft within that rectangle. If the craft moves out of the rectangle the servo-systems are operated to position the pen 46 in readiness for further course-recording, if, e.g. the craft again enters the rectangle from the South or West. Fig. 5 shows a modified arrangement of Fig. 4 in which the pen 20 and lead screw 21 are connected respectively to the wipers of potentiometers 94, 98, the voltages across which correspond to the vertical and horizontal lengths of the chart 14. Voltages of opposite phase to the voltages across potentiometers 94, 98 are applied across potentiometers 95, 99 and the wipers of the latter are manually pre-set so they receive a voltage representative of the lengths of the vectors V and H shown on chart 14. The wipers of potentiometers 94, 95 are connected to amplifier 44 associated with the lead screw 40 of the second course-recorder and the wipers of potentiometers 98, 99 are connected to amplifier 45 of the other servo-system of the second course-recorder, these amplifiers being also connected with the wipers of answer potentiometers 96, 100 which wipers are coupled with the pen 46 and lead screw 40 respectively. These potentiometers have applied thereto voltages which are in phase with the voltages applied across potentiometers 95, 98 and are equal to the wiper voltages thereof. The servo-motors 42, 43 are connected with the lead screws 40, 41 through clutches 97, 101. With this arrangement when pen 20 is within the dotted rectangle showing on chart 14 the position of the area depicted by the large-scale chart 69a, the pen 46 copies the movements of pen 20, whereas when pen 20 is outside this rectangle, pen 46 is held in a position ready for further course-recording should the craft again enter the area depicted by chart 69a. A modification is also described of the apparatus of Fig. 5 for use where the area represented on chart 69a is depicted on chart 14 by a rectangle inclined to the sides of frame 15 as e.g. when the charts are based on a straight-meridian conic projection, in which the amplifiers 44, 45 are fed by signals from sine/cosine potentiometers, these signals representing the co-ordinates of the position of the craft with respect to axes parallel to the sides of the dotted rectangle on chart 14 and intersecting at one corner thereof. In order to record on a circular chart 135 the path of a craft over a part of the arc represented by a straight meridian conic projection, the apparatus of Figs. 9, 10 may be used. The co-ordinates of pen 20 with respect to axes parallel to the sides of chart frame 15 and having their origin at the centre 136 of the circular chart area are determined by the potentiometers 94, 95, 98 and 99 and the summing amplifiers 111 and 116. The signals from the latter energize field windings 137, 138 of the stator of a sine-cosine resolver, the rotor winding 139 of which has an induced voltage