1、1400 单词， 2100 汉字 A MULTICHANNEL ELECTRONICDIGITALTAXIMETERTHAT CAN DEAL WITHMORE THAN ONEPASSENGER SIMULTANEOUSLY1 S.S. BEDAIR,The AIR FORCE Of The ARAB REPUBLIC OF EGYPT, 10 MostafaReda Street, Mania1 El Rqdah, Cairo, Egypt ABSTRACT In thispaper, a multi-channel taximeter that is able to deal more
2、than one with than passenger simultaneously is proposed. In order to demonstrate theory the of operation a complete of the proposed system, design an for experimental three-channel taximeter (whose prototype has been built under grant from the Egyptian Academy for Scientific Technologicaland Researc
3、h)is presened. System outline, diagrams well as detailed circuit diagrams for the experimental taximeter are also included. 1. INTRODUCTION Transporting people in the morning from their homes to their works and back in the afternoon has become a big problem in big cities especially in undeveloped co
4、untries. As a partial solution of this problem, the authorities in some countries had, unofficially, left the taxicab drivers to carry different passengers to different places at the same time. For example, a taxicab with four seats may carry four different passengers without any relation between th
5、em except that their way of travelling is the same. 2. AN EXPERIMENTAL THREE-CHANNEL TAXIMETER Theory of operation of our experimental device to work as an electronic digital taximeter is based on the fact that the speedometer cable rotates one revolution for each meter of travelling distance. Accor
6、dingly, if the speedometer cable is coupled with a speed sensor that generates a single pulse for each meter of travelling distance, then our taxi-meter could be three up counter modules associated with a speed sensor unit. However, our experimental is not simply a three display readouts. As a matte
7、r of fact it contains logic circuits that automatically changes the fare per kilometer of travelling distance of waiting time according to the number of passengers hiring the taxicab. The device may be splitted into two main parts: The first is the speed sensor unit which may be located anywhere in
8、the taxicab such that an easy coupling to the speedometer cable can be achieved. The second unit contains the main electronic circuit, the display and control panel. The unit should be located some-where in front of both the driver and the passengers. A possible components locations is shown in Figu
9、re 1. A. Speed Sensor Unit The main function of this unit is to supply train of pulses whose frequency is proportional to the angular rotation of the wheels. A possible form of a speed sensor is shown in Figure 2. 1Bedair, S.S.A MULTI-CHANNEL ELECTRONIC DIGITAL TAXIMETER THAT CAN DEAL WITH MORE THAN
10、 ONE PASSENGER SIMULTANEOUSLYJ.Vehicular Technology Conference, 1987(3):458-463. B. Main Electronic and Display Unit A suggested shape for the main electronic anddisplay unit is shown in Figure 3. The control and display panel containsall controls necessaryforoperating the taximeter aswell as four r
11、eadoutdisplays. The first channel will give the sum ofmoney required from the first passenger, while thesecond and thirdreadouts are forthe second andthird passengers, respectively. The fourth readoutwill give the total income of the taxicab. 3. DESCRIBTION OF THE MAIN ELECTRONIC CIRCUIT The general
12、 block diagram of the main electronicis shownin Figure 4. It consists of five circuit subcircuits designated by the symbols CT1 up to CT4as well as the display circuit and a number of supporting circuits, these are: The number of passengerdetection CT1, travellingdistance scalingcircuit CT2, waiting
13、 time scaling circuit CT3, circuitCT4whichgenerates clock pulses for the displaycircuit. A. Number of Passengers Detection Circuit CT1 As shown from the general block diagram, thecircuit CT1 has three inputs 1, 2 and 3 as well asthree outputs J, K and L. B. Tavelling Distance Scaling Circuit CT2 As
14、shown from the block diagram of Figure4, the circuit CT2 has four input J, K, L and E andone output M. The function of the circuitis tosupply a single pulse at the output M foracertainnumber of pulses generated attheoutput of thespeed sensor (certain number of meters travelledby the taxicab), accord
15、ing to the number of passengershiring the car. A suggested fare per kilometerof travelling distance is shown incolumn two ofTable 2. Thecircuit, in thiscase, should supplya single pulse at the output M forevery100, 125 or 143 pulses generated at the input terminal E according to the level of voltage
16、 at input terminate J, K or L, respectively. C Time Scaling Circuit CT3 As shownintheblockdiagram,thetimescalingcircuit will have four inputs J, K, L and F andoneoutput N. Thefunction of thiscircuit andaccording to column three of Table 2 (fare per 2 minutes of waitingtime) is to supply a singlepuls
17、e at the output N for every 120,240or 360 pulses supplied at theinput terminal F from the 1 Hz clockaccording to level of voltage at inputs J, K and L,respectively. Timescalingcircuitwould be similar to thedistance scalingcircuit but with different diving ratios. A Possible circuit diagram is shown
18、in figure7. D. Circuit CT4 Which Generates Clock Pulses for Display Circuit Thefunction of thiscircuit is to supplyone,two orthreepulsesat theoutput terminal R for eachpulsegenerated at any of theterminals N or M,accordingtothevoltagelevel at theinputterminalsJ, K or L, respectively. The output Pwil
19、l receivea pulseforeachpulsegeneratedat any of theinputterminals N or M. This function can be performed by the circuit shown in Figure 8. E. Display Circuit As shown inFigure2, thedisplay panelwould contain three4-digitdisplays that give the sumof money required from each passenger separatelyas well
20、 as a onesix-digitdisplay that gives totaltheincome of thetaxicab.A possible wiring diagram for thedisplaycircuitis shown Figurein9. Rotatingany of therotaryselectorswitchesto fullyclockwisedirectionwill supplythecorresponding display by 5 volts through terminals 1, 2 and 3, respectively. F .Changin
21、g Over Between Time and Distance Fares In thefollowing twopart,different methodsforchanging over between time anddistancefaresare suggested: The first isto switch to time fare whenever the distance fare is less than the time fare. The second alternation is to connect the input of the inverter inFigu
22、re 10 c. to theoutput terminalQ of thespeedometer circuit, Figure 2. G . Function of the Rotary Selector Switches The voltage levels that should be suppliedbythe terminalsof the rotary selectorswitches inordertoensure properoperation by the electronic circuit given are inTable 3. Connection of three
23、rotaryselectorswitches each with four decks offive poles each,that satisfy the logicfunction of Table 3, is shownin Figure10 a. Rotating any of the three switches into fully clockwisedirectionwillthrough pass fivepositions. The function oftherotaryselectorswitchescanbedescribedstartingfrom the first
24、 positionpassing throughvarious steps until reaching the final position. H. Supporting Circuits and Devices It can be easily seen that the mainelectroniccircuit will requiresomeadditional standard circuits,such as a 5 voltspower supply, with suitablepower,1 KHzand 1 Hzoscillator circuits. A need for
25、 a backup battery in order to store the contents of the total sum latches is inevitable. 4. CONCLUSION In thispaper,wehaveintroduceda multi-channeltaximeterthatcanbe hired for more than one passenger simultaneously. Theproposed taximeter will help in solvingthe problem of transportingpeople in big c
26、itiesespeciallyinundevelopedcountries by allowingtaxicabdrivers to carry different passengers to different places simultaneously .In order todemonstrate the theory of operation of the proposed system, a completedesign for an experimentalthree-channel taximeter(whoseprototype has been built undergran
27、t fromtheEgyptianAcademyforScientificandTechnologicalResearch) is presented. Finally,we should attractthe attention to astatisticalinvestigation whose results have shownthat some peopledo not thelike ideaof sharingtaxicabs with otherpeople.Hence, We recommendthat onlysometaxicabs be fitted with theproposedmulti-channel taximeter, while leavingtheothers with
