Patent GB-1362587-A (GB)
Title: Vehicle collision assessment apparatus
IPC: G01S13/937
Filed: 1971-11-01
Abstract: 1362587 Radar SPERRY RAND CORP 1 Nov 1971 [5 Nov 1970] 50622/71 Heading H4D In a manoeuvre assessment display system for mobile vehicles sensor means generates coordinate and velocity component data of a first vehicle with respect to a second vehicle, computing means responsive to said data computes a predicted track for the first vehicle to a point of probable collision with the second vehicle, and a region of possible collision therewith about said point, and display means displays said predicted track and said region of possible collision relative to each other. As described, a conventional marine pulsed radar system 21, Fig. 3, with a directive azimuth scanning aerial 21a, provides an off-set type P or plan position presentation on the screen of a cathode-ray tube (CRT) 22. The radar system also supplies synchronizing and other signals over a lead 26 to a track-while-scan system 25, the operation of which is controlled by signals from a light-pen 23 over a lead 24. Output from the track-while-scan system 25 is taken over a lead 27 as one input of a computer 28. Other inputs to the computer are derived from the ship's gyro-compass 40, speed sensor 41 and from a timer 29. The computer 28 drives a line symbol generator 31 and a circle symbol generator 35 over respective pairs of leads 32, 33 and 36, 37. The said generators also receive inputs from the timer 29. A synthetic display is presented on the screen of a CRT 20, and the generators 31, 35 provide inputs thereto over respective leads 34, 34a, 39 and 38, 38a. Operation.-The position of own ship is represented at location 1 near the bottom of the screen of the CRT 22. A target ship of interest is represented at a location 22a and it is selected by placing the light-pen 23 thereupon. When the target image is next intensified, as scanning proceeds, an electrical impulse is transmitted to the track-while-scan system 25, which stores positional data in respect of the target and updates it with each succeeding scan until the operation is manually disabled. Other targets may also be selected at the will of the operator, and data for all targets may be supplied on a time-sharing basis to the computer 28. Said data may include velocity as well as positional particulars, or only the latter, when the velocity calculations are performed in the computer instead of in the track-while-scan system. For each target a prediction is made in the computer of a point or points of probable collision assuming that the target's present speed and course are maintained, and that own ship's present speed is maintained. Signals representative of the co-ordinates of present positions and of the predicted points are fed from the computer to the line symbol generator 31. There is also calculated for each predicted point a range of uncertainty, and signals representative thereof are fed to the circle symbol generator 35. The display on the screen of the CRT 20 is shown enlarged in Fig. 1 and comprises the point 1 representative of own ship, a heading line 3 extending upwardly therefrom, which indicates its course, a number of track lines such as 4 joining the present and predicted positions 5, 7 of a selected target, and circles such as 6 around the predicted position of a target. The minimum radius of a circle is the said range of uncertainty, but this may be increased if desired by means of a manual control 35a on the circle symbol generator 35. A transparent display may be superimposed over the screen 2 and be moved in correspondence with own ship under control of the gyro-compass 40 and the speed sensor 41. Video superposition of symbols &c. may be effected by flying spot scanning.