Patent GB-582168-A (GB)
Title: Improvements in or relating to means for navigation, aerostation and like determination of the movements of vehicles relative to their surroundings
IPC: G01S13/75
Filed: 1941-09-17
Abstract: 582,168. Railway signalling. WALTON, G.W. Sept. 17, 1941, No. 11875. [Class 105] [Also in Groups XX, XXIX, XXXV, XXXVIII and XL] A navigation or like system comprises one or more markers " formed as diffuse reflectors of short waves (or comprising means for repeating or transmitting short waves), an instrument for detecting the markers by means of waves radiated by a transmitter associated therewith, means incorporated in the instrument for ascertaining the direction and/or distance of the markers, and means for indicating the position of the instrument (and therefore of the vehicle carrying the instrument) relative to one or more of the markers or other reference points, such as geographical positions. The detecting instrument, transmitter, and indicating apparatus may be carried by an aircraft, ship, train, or other vehicle, and the " markers " may be in a fixed position in or on the ground (e.g. along river or canal banks, on bridges, roads, railway tracks, etc.) or may be carried by another vehicle or on a balloon, buoy, or raft. The marker may be identified (a) by the characteristic shape of the conductor constituting the diffuse reflector, or (b) by the characteristic signal emitted when the marker is selected and made operative by a beam of waves projected thereon. The characteristic shape of the diffuse reflector may be indicated as a visual image as described in Specification 582,482, [Group XL], or by a scanning process. Construction of markers. The markers may be formed as a series of juxtaposed imageforming members with spherical, etc., surfaces fixed in a common support, as spherical deformations in a metal sheet, by spraying metal on a lenticulated surface, by pressing rows of corrugations in expanded metal, and in other, ways, Figs. 2 to 10 (not shown). The diffuse reflector may be embedded in such materials as concrete, e.g., in a railway sleeper or in the runway of an aerodrome, or in plastic mouldings flush with the surface of an aeroplane fuselage. The reflectors may take the form of barbed airows or other patterns embedded in concrete, Figs. 11, 12, 13 (not shown). In another form, the reflector may be a hollow body containing a wireless receiver which causes an associated transmitter to emit characteristic signals, Fig. 14 (not shown). Reflectors on road and other vehicles for indicating direction of movement, etc., may be arranged as shown at 41 ...45, Fig. 15, particular indications being derived by suppressing diffuse reflection from certain parts by covering them with a plain metal sheet, or by rotating parts to the end-on position, or in other ways. Detecting instruments for short-range navigation and screens for use therewith. The detecting instrument may provide a visible image of the reflector, e.g.; as described in Specification 582,482, and this image may be formed or projected upon a transparent screen specially ruled to enable deductions to be drawn from the position of the image on the screen. Screens specially ruled for use on ships, canals, railways, and road vehicles are described, Figs. 16 to 19, respectively (not shown). An adjustable measuring device for use with such a screen comprises a small transparent screen, having cross-line rulings, the screen being movable in two directions at right angles. An additional transparent screen having a single line thereon is movable relatively to the screen having crossline rulings and serves to measure the diameter of the image, Fig. 20 (not shown). Landing indicator for aircraft. The runway of an aerodrome may have a line of markers along both edges and another transverse line, i.e., in plan view an elongated H. The screen 87, Fig. 21, upon which an image of the markers is formed, has a ruled line 110 (parallel with the axis of pitch), and there are three additional rulings 111, 112 on a transparent screen 103 - which is rotatably mounted in a frame 88, arranged to move parallel to the screen 87. Movement of the frame 88 is effected automatically by a pendulum 100 moving about an axis in the plane of the Figure, and rotation of the screen 103 is effected by a pendulum 108 moving about axis 109. A pilot approaching the runway correctly will see images of the runway markers parallel to each of the lines 111, 112 and parallel to line 110 when the plane is not banking. During banking; gliding, and landing the pendulums cause relative movement of the screens 103 and 87, so that lines 111, 112 move relatively to line 110. The pendulums may be replaced by pendulum-controlled gyroscopes. Long-range working. " Markers " emitting characteristic signals may be identified by looking them up in a table, or the markers may emit signals giving their latitude, longitude, and altitude. In order to control courserecording or course-following apparatus on a map or chart, the angles of elevation and azimuth of the indicating instrument, and its distance from the marker, must be converted into signals representing.the difference between the altitude, latitude, and longitude of the marker and of the indicating instrument and these signals must be added to the corresponding signals representing the altitude &c. of the marker. These mathematical computations are made by the apparatus described in Specification 560,928, [Group XL], as described later. Course-recording and indicating apparatus. Currents representing the true latitude and longitude of the indicating instrument control the admission of pressure to pipes 146, Fig. 22, connected to cylinders 138, 144, the pistons 137, 143 of which are connected to cranks 135, 141 carried by hollow sleeves rigid with arms 119, 132 connected to a plate 121 and an arm 125 carrying the recording pen 126, optical device &c., over a map on the table 113. Links 123, 127, 128 complete the parallelogram, but are only necessary when more than one tracing or following device is used. When a photoelectric course-following device is used, this is carried at the point 126 and is so mounted that it can be automatically rotated so as to lie at the correct angle to the course line to be followed. In an alternative recorder, Fig. 25, pressure applied at equal rates to both pipes 183 moves both pistons 181, 182 outwards, thus moving the pivot 174 carrying the tracer 185 downwards. When pressure is applied to one pipe 183 and exhaust to the other, the pivot 174 moves horizontally. The two movements may be combined to give any desired movement to the tracer. In a third recorder, Figs. 32-37 (not shown) which traces or follows simultaneously course, altitude, and speed lines, the spindle carrying the tracing or following device is rotated by four eccentric rods each of which engages an individual eccentric carried by tubular sleeves connected by links &c., to the tracer. The four eccentric rods are connected at their other end to eccentrics on a common pivot (Fig. 34), these eccentrics in turn being connected by four other eccentric rods to eccentrics on a series of concentric sleeves (Fig. 35) controlled by angular pistons of a servo-motor. In a course-indicating apparatus, Figs. 40, 41 (not shown) in which a small map is optically projected on a screen, the position of the ship and its direction of movement is also optically projected on the same screen. A glass disc, bearing a radial line indicating the direction of movement, and a short cross line at the centre of the disc indicating the position of the ship, can be moved bodily by eccentric mechanism under control of two shafts and can be angularly rotated by further eccentric mechanism under control of a third shaft, so as to vary the position of the cross line and the direction of the radial line. Photo-electric controlling apparatus. The photo-electric device, Fig. 27, is carried in the hollow pivot 126, Fig. 22, of the course-tracing or following apparatus. An optical system 218, Fig. 27, projects an image of the course-line drawn on the map through lenses 226, 229 on photo-electric cells 227, 231. Normally the image falls on the bar 225 between the lenses, so that equal amounts of light fall on the cells. When the ship deviates from the desired course, the image is displaced, and more light falls on one cell than on the other, the differential effect being used to control the steering of the vehicle. In order to ensure that the bar 225 may be kept parallel to the course line on the map, the photo-electric apparatus must be controlled by the direction of the course line or by the actual course of the vehicle. For this purpose, the photo-electric apparatus is rotatably mounted in the hollow pivot 126, Fig. 22, and is positioned angularly by fluidpressure servo-motor apparatus, Fig. 23 (not shown), controlled by four photo-electric cells through solenoids, Fig. 28 (not shown). In a modified apparatus, the image of the course line is reflected by a prism, so that it is formed horizontally instead of vertically, Figs. 38, 39 (not shown). Compensating for rolling and pitching of vehicle. For this purpose, the instrument carried by the ship, &c., may be mounted in gymbals so that its angles of azimuth and elevation are independent of the movement of the ship, but preferably' the instrument is mounted to turn about vertical and horizontal axes fixed relatively to the ship, and corrections are made for the movement of the ship. Various methods of correcting are described, one involving the use of a compass or pendulum, Fig. 29 (not shown). Use of course-tracing or following mechanism with maps of different scale or kind of projection. In order that the movement of the tracer may be checked against the position of the indicating instrument, by means involving the use of the remote control system described in Specification 560,928, the linear movement of the tracer is converted into angular movements of two shafts, the apparatus being so designed that it may be used at will with maps of different scale or different systems of projection, Fi