Builders guide robot pacman.pdf

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ed LED on the maze. Therefore, the dot counting circuit is improved by placingtwo sensors side by side.The dot counting system should output a high signal if either one of the sensors orboth sensors detect the LED. Therefore, the outputs of both sensors are sentthrough an OR-gate. The output signal from the OR-gate is then sent to themicrocontroller.5.3 Pac-Man TrackingAs Pac-Man roams round the maze, Ghost should be able to detect Pac-Man’spresence when they are within close proximity. Several implementations wereconsidered including radio frequency for transmitting absolute position data,overhead camera for image processing, and sonar for detecting the reboundedsignal from Pac-Man. However, we decided that the best way to implement thisfunctionality is to mount an infrared beacon on Pac-Man, and wide-angle infraredreceivers on Ghost.The basic concept is simple: Pac-Man transmits an infrared signal in 360-degreecoverage. Depending on the varying signal intensity of the infrared receivers,Ghost should be able to determine the general direction and distance of Pac-Man.The receiver modules we use are PNA4612 (Figure 25), which detects IR signalmodulated at 38kHz. Not only is PNA4612 sensitive to a specific transmitterfrequency, but also it is sensitive to an emitter wavelength at around 960nm.These features make PNA4612 particularly attractive since it effectively blocksoff IR interference. The beacon detector on Ghost consists of four receivermodules arranged to detect signals from front, left, right and back. Testing resultsshow that PNA4612’s detection range is well beyond the120cm requirement.Upon further testing, however, we discovered an unfavorable outputcharacteristic. The active low output signal becomes an aperiodic pulse trainwhen the IR source is around a 90cm range. The length of the on-period of such apulsing output is inversely related to the distance between 80cm and 100cm untilthe output becomes a flat 5V beyond 120cm. In order to convert such an irregularoutput into a usable signal, we fed the output to a low-pass filter to turn the pulsesignal into a smooth analog voltage level, which can be easily interfaced with themicrocontroller’s A/D converter. (See Figure 26)19
J1V310V+VR91MC1220nFOutputFigure 25. PNA4612Figure 26. Beacon Receiver CircuitThe IR beacon module on Pac-Man, as shown in Figure 27, consists of a 555timer used to produce a 38kHz square wave and IR emitters with a maximumoutput wavelength at 960nm. The resister and capacitor values chosen werecalculated by the following formula where T1 is the On period, and T2 is the Offperiod of the square wave. The duty circle is set at 60%:T1 = 0.6*(1/38000)T2 = 0.4*(1/38000)T1 = 0.693*( RA + RB)*CT2 = 0.693*RB*CV25V+VU1555RA7.784k 40%R8680R7680R6680R5680R4680R3680GndTrgOutRstVccDisThrCtlRB15K10nFC1nFFigure 27. IR Beacon Circuit.20
Page 1 and 2: PAC-MANEECE 474 - Team 1July 24, 20
Page 3 and 4: Table of ContentsList of Tables ...
Page 5 and 6: List of TablesTable 1. Encoding sch
Page 7 and 8: AbstractThe EECE474 Pac-Man project
Page 9 and 10: 2.0 ChassisThe design objective of
Page 11: casters in the back. For any two wh
Page 14 and 15: Figure 10. 55M048B2U 12VDC Unipolar
Page 16 and 17: 4.0 Radio Frequency ApplicationSinc
Page 18 and 19: Table 1. Encoding schemeUp 100Left
Page 20 and 21: is held for several clock cycles an
Page 22 and 23: Figure 20. Receiver Block DiagramTh
Page 24 and 25: Figure 21. GP2D12However, it also h
Page 28 and 29: Since the beacon signal needs to co
Page 30 and 31: 6.0 Microcontroller and SoftwareOur
Page 32 and 33: Figure 31. Pin assignments for Pac-
Page 34 and 35: Table 2. RF signal format for Pac-M
Page 36 and 37: We know that the timer counts at 1
Page 38 and 39: Figure 40. Pin assignments for the
Page 40 and 41: The measurements for the right and
Page 42 and 43: 7.0 MazeThe maze is the area in whi
Page 44 and 45: Table 4. Truth table of the Memory
Page 46 and 47: 8.4 RegulatorsRegulators were added
Page 48 and 49: 9.0 RecommendationsRFIn order to re
Page 50 and 51: 10.0 ConclusionThe design and imple
Page 52 and 53: APPENDIX A: Photo GalleryPac-ManGho
Page 54 and 55: APPENDIX B: PCB LayoutsPac-ManBotto
Page 56 and 57: GhostBottom Layer (PIC, motor, cont
Page 58 and 59: MazeLEDs and sensor circuit
Page 60 and 61: APPENDIX D: Gantt chartWeek 1(May 6
Page 62 and 63: Pac-Man Source Code/***************
Page 64 and 65: }}}next_turn = NONE;turn_ready = 0;
Page 66 and 67: MIN_RIGHT += read_adc();}output_bit
Page 68 and 69: if ( (ob_left > MAX_LEFT) || (ob_ri
Page 70 and 71: Ghost Source Code/*****************
Page 72 and 73: }case S:}go_forward();break;}curren
Page 74 and 75: }if ( walls & SOUTH )return 0;elser
Page 76 and 77:
}queue_count = 0, queue_index = 0,
Page 78 and 79:
}}}turn_enable = 0;turn_180 = 0;tur
Page 80:
{// Look for Pac-Man's beacon signa
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