GB985570A - Traffic density computer - Google Patents

Traffic density computer

Info

Publication number
GB985570A
GB985570A GB3239061A GB3239061A GB985570A GB 985570 A GB985570 A GB 985570A GB 3239061 A GB3239061 A GB 3239061A GB 3239061 A GB3239061 A GB 3239061A GB 985570 A GB985570 A GB 985570A
Authority
GB
Grant status
Application
Patent type
Prior art keywords
circuit
density
traffic
speed
output
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
GB3239061A
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
LABORATORY FOR ELECTRONICS Inc
Original Assignee
LABORATORY FOR ELECTRONICS Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date

Links

Classifications

    • GPHYSICS
    • G06COMPUTING; CALCULATING; COUNTING
    • G06GANALOGUE COMPUTERS
    • G06G7/00Devices in which the computing operation is performed by varying electric or magnetic quantities
    • G06G7/12Arrangements for performing computing operations, e.g. operational amplifiers
    • G06G7/16Arrangements for performing computing operations, e.g. operational amplifiers for multiplication or division
    • G06G7/163Arrangements for performing computing operations, e.g. operational amplifiers for multiplication or division using a variable impedance controlled by one of the input signals, variable amplification or transfer function
    • GPHYSICS
    • G06COMPUTING; CALCULATING; COUNTING
    • G06GANALOGUE COMPUTERS
    • G06G7/00Devices in which the computing operation is performed by varying electric or magnetic quantities
    • G06G7/48Analogue computers for specific processes, systems or devices, e.g. simulators
    • G06G7/76Analogue computers for specific processes, systems or devices, e.g. simulators for traffic
    • GPHYSICS
    • G08SIGNALLING
    • G08GTRAFFIC CONTROL SYSTEMS
    • G08G1/00Traffic control systems for road vehicles
    • G08G1/01Detecting movement of traffic to be counted or controlled
    • G08G1/0104Measuring and analyzing of parameters relative to traffic conditions

Abstract

985,570. Electric analogue calculating; road traffic control systems. LABORATORY FOR ELECTRONICS Inc. Sept. 8, 1961 [Sept. 8, 1960], No. 32390/61. Addition to 949, 382. Headings G4G and G4Q. In the traffic density computer described in the parent Specification means are provided for computing traffic volume over a sampling time base which is variable inversely with the average speed output of the traffic speed computer so that the output of the traffic volume computer represents traffic volume for a constant distance of the roadway from a given measurement point thereon. Fig. 1 shows a modification of the circuit of Fig. 1 of the parent Specification wherein instantaneous traffic volume rate circuit 17 energizing linear cathode follower circuit 18 with feedback circuit 18 with feedback circuit 46, 47 feeds directly the division circuit 75, and volume and speed timebase correlation circuit 69 controlling speed averaging circuit 21, with a volume rate signal; the division circuit also receiving an average speed signal from the circuit 21. The averaging base circuit 19 comprising parallel circuits of variable resistances and opposed diodes defining the averaging time segment succeeds the division circuit 75 and feeds output amplifier circuit 20 to produce a signal representing computed traffic density by dividing volume by speed which by adjustment of the forward and reverse time constants of circuit 19 may be given a response which is more rapid for increasing density than for decreasing density or vice versa. The time constant of volume rate circuit 17 may be adjustable. Alternatively (Fig. 2) an additional averaging base circuit 19A comprising a variable series resistance shunt capacitance time constant circuit is connected between circuits 18 and 69, 75 while an averaging base circuit 19B similar to 19 followed by amplifier 20 succeeds division circuit 75 as in Fig. 1. The traffic density is averaged as in the parent Specification over a constant time segment and thus over a distance segment proportional to average traffic speed. In Fig. 3, series resistance 46<SP>1</SP> and shunt capacitor 48 constitute the averaging base circuit 19 establishing the averaging time segment which follows cathode follower 18. Resistance 46<SP>1</SP> is manually variable by limb 132 together with thermally variable resistance 58 of thermistor potentiometer 59 and the gain 133 of servo-amplifier 67 (see Fig. 1 of the parent Specification) whereby the time segment of circuit 19 is adjustable together with correction of the speed averaging circuit 21, so that the effect of the passage of a single vehicle is diminished as the number of vehicles passing during a particular time segment increases and vice versa. In a modification (Fig. 4) enabling traffic density to be computed for a fixed distance instead of a fixed time (i.e. a distance proportional to average speed) the time segment is made to vary inversely with average speed instead of being fixed. Servomotor 68 of speed averaging circuit 21 (Fig. 1 of the parent Specification) adjusts variable resistor 46<SP>1</SP> and the effect of the reduced time base and passage of fewer vehicles correspondingly corrects the effect of an individual vehicle average speed; the thermistor potential divider being corrected as before by volume and speed base correlator 69. Alternatively (Fig. 5, not shown) the thermistor potential divider may be controlled solely from the computed density output signal. A CR circuit giving a similar time constant for increase and decrease in volume rates may be placed between circuits 18 and 20 while a circuit similar to 19 giving variable and differing rates for increase and decrease of density variation may be provided at the density computer output. Fig. 6 shows in block form a complete system for determining traffic density over a constant distance base incorporated the above modifications;and Fig. 7 shows a modification for selectively switching the distance base to several alternative values wherein knob 134 selects alternative values of resistors R46<SP>1</SP> for co-operation with time constant capacitance 48 between cathode follower 18 and output amplifier 20 to vary the time base and corresponding values of R58 for co-operation with R59 in the thermistor potential divider circuit between leads 61, 62 in speed averaging circuit 21 to correspondingly vary the time base thereof so that the computed density is measured over the same time base;all such alternative resistors R58 being gauged for adjustment by servomotor 68 as above,while R59 is varied from either the volume output or density output. The thermistor potential divider R58, R59 may comprise a single thermistor in a temperature controlled enclosure, in series with an ohmic resistor,and heated by a control winding as in the parent Specification. Fig. 8 shows a traffic control system in block form incorporating two radar sensing units 10 responding to traffic in opposite directions (inbound Ib, outbound OB) feeding speed and impulse translators 11 as described in the parent Specification, operating traffic density computers of the kind described above. The outputs representing densities in opposite directions are applied to segmental scale circuits each of which provide selective outputs on one of six output circuits when the respective density signal falls within a predetermined segment of the full scale of densities. The segmental scale circuits operate a system selector operating to select a particular output when inbound density is substantially greater than outbound density, a second output when outbound density exceeds inbound density, and a third output or a combination of the first and second outputs when the inbound and outbound densities are similar. The selected outputs may supervise a traffic control system, or control the direction of flow in one or more reversible traffic lanes in accordance with the traffic density in each direction.
GB3239061A 1960-09-08 1961-09-08 Traffic density computer Expired GB985570A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
US3239653A US3239653A (en) 1960-09-08 1960-09-08 Traffic density computer
US3341698A US3341698A (en) 1960-09-08 1965-06-07 Computer for dividing one variable quantity by another

Publications (1)

Publication Number Publication Date
GB985570A true true GB985570A (en) 1965-03-10

Family

ID=26736967

Family Applications (1)

Application Number Title Priority Date Filing Date
GB3239061A Expired GB985570A (en) 1960-09-08 1961-09-08 Traffic density computer

Country Status (2)

Country Link
US (1) US3341698A (en)
GB (1) GB985570A (en)

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2749036A (en) * 1950-10-07 1956-06-05 Goodyear Aircraft Corp Means for preventing computing errors in a multiple potentiometer computing element
US2919067A (en) * 1955-05-25 1959-12-29 Ibm Ratio measuring apparatus

Also Published As

Publication number Publication date Type
US3341698A (en) 1967-09-12 grant

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