Builders guide robot pacman.pdf

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7.0 MazeThe maze is the area in which Pac-Man and the Ghost travel. There are 24 dots,represented by red LEDs, and 24 photoresistors on the floor of the maze. Each dot isturned off after Pac-Man travels across it.Like the computer Pac-Man game, we wanted to create a setting in which Pac-Man can“eat dots.” We came up with two approaches. One was a mechanical design, whichcomposes of a gate on the maze and a switching system under the floor. The gate wouldbe pushed open when Pac-Man travels across the gate. Then, the switch that is connectedto the gate will be opened and the “dot” will be turned off. However, this design hasmany limitations. For example, users need to manually set the gates back to the originalposition to reset. Moreover, building the gate on the maze takes too much time, addsclutter to the maze and is unreliable. Therefore, we decided to go with the secondapproach, which uses sensors to detect Pac-Man and turn off the LEDs. The details ofthis design are discussed below.7.1 Physical DimensionWe had two choices in the type of material to use for the maze: cardboard orwood. We decided to go with wood since it was readily available from themachine shop. The walls are painted white, since they work best for the obstacledetectors and the ground black. The dimension of the maze is 122cm x 122 cmand is evenly divided into 36 squares – 6 rows and 6 columns. The thickness ofthe walls is 2 cm; the positions of the walls are designed so that there are straightlanes and 90 degree turns in the maze (see Figure 45 below). The width of eachlane is 18.5 cm with 1- 2 mm tolerance.Figure 45. Maze DesignThe height of the outer walls is 22cm and the inner walls are 16cm high. Theouter walls were designed to be higher than the robots in order to avoidinterferences, such as visible light and infrared, outside of the maze. The innerwalls are shorter than the robots so that the Ghost is able to locate Pac-Manthroughout the maze with a beacon sensor.35
7.2 DotsThe dots on the maze are implemented with CMOS chips and a simple circuit.The following is the connection diagram for one dot on the maze. In general, ared LED is ‘ON’ at the beginning and after being reset. Then, it is turned offwhen a sensor corresponded to the red LED senses a super bright white LED thatis placed at the bottom off the Pac-Man robot.Figure 46. Dot Circuitry for the Maze (for one dot)The first part of the dot circuit is a comparator. The comparator outputs low whenlight with certain intensity is sensed; otherwise, it outputs high. As shown in theabove diagram, the reference voltage is connected to the positive terminal and thephotoresistor along with a 4.7k resistor, is connected to the negative terminal.When the sensor senses light, its resistance decreases. As a result, the voltage tothe negative terminal increases. When the negative terminal voltage is higherthan the positive terminal voltage, the comparator outputs zero.− RsV =4.7k+ RsThe voltage measured across the negative terminal is around 2.4V under thecondition that all the lights in the room are turned on. When a super bright whiteLED is located on top of the photoresistor, the measured negative terminalvoltage is in a range from 3.8V-4.1V. Therefore, the reference voltage that isconnected to the positive terminal is set to 3.62V. The design is good because itis sensitive only to the light emitted by the super bright white LEDs and it isstable.The second part of the dot circuit is a memory device. After a light is sensed, itturns off a dot on the maze and saves the “OFF” stage until users reset the dot. ANAND R/S latch (CD4044) is chosen. The following is the truth table for thememory device.36
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 26 and 27: ed LED on the maze. Therefore, the
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 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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