Patent GB-1245871-A (GB)
Title: Vehicle anti-collision automatic control system
Inventor: LALONE FRANCIS G
IPC: G01S13/931
Filed: 1969-04-11
Abstract: 1,245,871. Anticollision radar for vehicles. MICRO ELECTRONICS INTERNATIONAL Inc. 11 April, 1969, No. 18646/69. Heading H4D. A vehicular anticollision device comprises a radiator of a constricted microwave beam 12 (Fig. 7) reflected from an obstacle directly to the front and received by an antenna carried by the vehicle; the radiator consisting (Figs. 4, 5, not shown) of a forward waveguide receiving energy from a klystron 26 flanged thereto and coupled to a parabolic reflector 36 with straight horizontal edges, provided with a centrally projecting tapered waveguide with a symmetrically apertured resonant cavity mounted thereon. The trailing end of the forward waveguide has a lateral equi-armed hybrid T guide carrying diodes 63, 64 at the terminations, and a further waveguide introducing a 90 degree twist is mounted parallel to the forward waveguide and elbowed thereto adjacent the klystron and the lateral arm, while a manually-operable screw-in attenuator is fitted to the forward guide for equality of diode output for forward radiation with zero reception. For zero relative motion between the vehicle and the obstacle, there is zero Doppler between transmission and reception so that the diode outputs are equal in amplitude and phase, but relative motion introduces Doppler variations of + 90 degree phase for closing and - 90 degree phase for opening, with equal amplitudes, and Doppler frequency proportional to rate of opening or closing. The Doppler frequency signals detected by diodes 63, 64 are amplified at 76, 77 in channels A, B; amplifier A being gain varied by a speed distance input 78 proportionally to vehicle speed and its output is detected to a variable D.C. proportional to rate of opening or closure, which is fed to sum network 80. The output of 76 is squared and amplified at 81, 81<SP>1</SP> and differentiated at 82 to positive pulses triggering monostable multivibrator 83 to produce pulses applied to a discriminator 84 controlled by gate 87 driven by the squared and amplified output of 77, whereby the discriminator is opened for + 90 degree phase shift between channels A, B and closed for - 90 degree phase shift. Opening Doppler signals are thus rejected and closing Doppler signals are converted to the Doppler frequency D.C. signal fed to gate 89 and summation circuit 80, which operates only when D.C. appears at output of 88 to produce a variable D.C. signal functional of the closing rate, the separation distance, and the vehicle speed. After amplification at 90, the signal is applied to control the brake 92 and throttle 93 of the vehicle if (a) an obstacle obturates the microwave beam; (b) is located at a distance therefrom such that the operation of the vehicle is hazardous, with regard to its speed and braking capacity; (c) the closing rate is such as to indicate danger of collision so as to maintain a safe distance between the vehicle and another vehicle or an obstacle. The amplifying squaring, differentiating and gating circuits are transistorized and the speeddistance input circuit (Fig. 9) is energized from the ignition distributer 188 through attenuator 192, 193, amplified by transistor 196, and amplitude clamped by Zener diode 200 to a train of pulses of frequency proportional to engine speed, which are applied to diode-resistancecapacitance discriminator 204, 208, 210 to develop a D.C. proportional to the engine speed, which is transistor coupled to control the gain of a transistor amplifier (Fig. 8, not shown) inversely as vehicle speed. Circuit waveforms for different measurement conditions are given (Figs. 13, 14, 15, not shown). When the vehicle is closing, the control signal is transistor coupled to energize solenoid 320 (Fig. 11) whose plunger operates brake servo 92 proportionally to the rate of closure, vehicle speed, and distance from the obstacle; while a further transistor 328 is normally biased to cut-off until the control signal reaches a preset value, at which transistor 334 energizes solenoid 338, whose plunger is displaced against a return spring either to tap the accelerator pedal as a warning of excessive speed, or to override it to release the throttle. Power is derived from the vehicle battery over RC ripple suppression and Zener stabilization for low voltage, and over free-running transistor multiplier, saturable core transformer, full-wave rectifier RC filter and Zener stabilization (Fig. 12, not shown). Typical component values are given. Speed distance signals may be obtained from the speedometer or engine alternator, e.g. in diesel or turbine-engined vehicles.