Transcript ppt
ECE 477 Design Review Group 7 Spring 2005 Outline • • • • • • • • • • Project overview Project-specific success criteria Block diagram Component selection rationale Packaging design Schematic and theory of operation Preliminary PCB layout Software design/development status Project completion timeline Questions / discussion Project Overview An autonomous vehicle designed to look for moving heat-emitting targets and engage them while patrolling a limited area and avoiding ground obstacles. + = Project-Specific Success Criteria • An ability to detect a heat-emitting target • An ability to determine and display the number of engagements and battery level • An ability to fire the weapon • An ability to turn weapon to face target • An ability to avoid collisions with inanimate objects Block Diagram AirSoft gun (1) Passive IR sensors (4) LCD screen/Shift Register (1) Ultrasonic sensor (1) Freescale HC(S)12 (1) H-Bridge for Drive Motors (1) Servo motor (1) Component Selection Rationale • • • • • • • Microcontroller Ultrasonic Sensors Passive Infrared Sensors (PIR) Robot Base Liquid Crystal Display (LCD) Servo Motor Paintball Gun Component Selection Rationale • Micro-controller: Motorola M68MOD912C32 - Pre-made DIP Module - Contains requisite I/O - Instruction Set/Capability Familiarity Component Selection Rationale • Ultrasonic Sensors: Devantech SRF04 - Ease of use - Small size - Low cost Component Selection Rationale • Passive Infrared Sensors: Kitsrus K30 - Easy to interface. - Good range ( Approx. 120 degree spread ) - Low cost Component Selection Rationale • Robot Base: Rogue Robotics RT-ATR - Easy to control ( 2 geared motors ) - Flexible/Expandable design - Multiple levels - Came with H-bridge Component Selection Rationale • Liquid Crystal Display: Optrex DMC20261A - Free - 20 Chars x 2 Lines - Backlit - Heavy-duty Component Selection Rationale • Servo Motor: JR NES-537 - Easy to interface/operate compared to stepper motor - High torque rating ( 45 oz-in ) - Very small/lightweight - Low cost - 120 degree range Component Selection Rationale • Paintball Gun: KTC 210910 - Fully Automatic - Electronic Trigger - Small ( 9” after cut down ) - Light weight ( less than 1 lb ) - Easily interfaced Packaging Design – Front View Packaging Design – Side View Schematic/Theory of Operation • • • • • • • • Voltage regulators LCD interface PIR interface Ultrasonic sensor interface Servo interface H-Bridge and drive motors interface Gun trigger interface Battery level indicator Schematic/Theory of Operation – Voltage Regulators • Power supply for microcontroller module and other digital components: – Linear Tech LT1376-5 switching regulator – Step down from 14.4 V input to 5 V regulated output – Can supply up to 1.25 A current – Up to 88% efficiency, typically around 86% Schematic/Theory of Operation – Voltage Regulators • 10 mH Inductor because the current draw could be more than 0.6 A Schematic/Theory of Operation – Voltage Regulators • Power supply for motors: – Linear Tech LT1374-5 switching regulator – Step down from 14.4 V input to 5 V regulated output – Can supply up to 4.25 A current – Up to 90% efficiency, typically around 88% Schematic/Theory of Operation – Voltage Regulators • 10 mH Inductor because the current draw could be more than 3.5 A Schematic/Theory of Operation – LCD interface • Utilizes the SPI capability of the MCU • A shift register, 74HC164, will be used to register data to be displayed on the LCD • Pin PM5 will be used to supply SCK to the shift register • Pin PM4 will be used to supply SDO to the shift register • Pin PM3 will be used to supply RS to the LCD module • Pin PM2 will be used to supply Enable to the LCD module • A 7x2 header will be used to connect LCD to the PCB Schematic/Theory of Operation – LCD interface Schematic/Theory of Operation PIR interface • Four PIR (passive IR) sensors to detect heat emitting moving objects • AN0 to AN3 will be used to receive the inputs from the sensors • 9 V pulse when a heat emitting moving target is detected • A voltage divider is used to reduce the voltage input to the MCU to 5 V • Resistors with the values of 1 kW and 1.2 kW will be used as the voltage divider Schematic/Theory of Operation PIR interface Vout = (Rbelow/(Rup+Rbelow)) * Vin 5 = (Rbelow /(Rup+Rbelow)) * 9 Rbelow /(Rup+Rbelow) = 5/9 1.2 kW / (1kW + 1.2 kW) 5/9 Schematic/Theory of Operation Ultrasonic interface • PT7 will output trigger pulse to the sensor • PT6 will receive the input pulse from the ultrasonic sensor • Distance is determined by how long the input pulse is held high Schematic/Theory of Operation Servo interface • Pin PT4 will be used to output pulses regulated by the built-in PWM to the servo to rotate the gun turret • Wiring setup image courtesy of Parallax, Inc. Schematic/Theory of Operation H-bridge and motors interface • PT0 to PT3, will be used as output pins to the H-bridge to drive the direction of the robot and PWM will be used to control the speed of the motors • Drive motors will be connected and powered through the Hbridge • The power supply to the drive motors will be regulated by the LT 1374-5 converter • The H-bridge’s power will be regulated by the LT 1376-5 converter • H-bridge image courtesy of Rogue Robotics Schematic/Theory of Operation Gun trigger interface • PM0 will be used as trigger • The gun will be optically isolated from the MCU • 4N28 opto-isolator will be used Schematic/Theory of Operation Battery level indicator • AN4 will be used to receive an analog voltage reading from the power supply to indicate the current level of the battery • 10-bit analog input and the analog to digital (A/D) converter will convert the input voltage to a digital value that can be used to compute the current battery level • Will be displayed on the LCD • A voltage divider is used to reduce the voltage input to the MCU to maximum 5 V • Resistors with the values of 2.2 kW and 1.2 kW will be used as the voltage divider Schematic/Theory of Operation PIR interface Vout = (Rbelow/(Rup+Rbelow)) * Vin 5 = (Rbelow /(Rup+Rbelow)) * 14.4 Rbelow /(Rup+Rbelow) = 5/14.4 1.2 kW / (2.2 kW + 1.2 kW) 5/14.4 Preliminary PCB Layout Start Reset Gun Clear LCD Display Battery Level Software Design Pause for 10 Seconds Display Engagements Set Engagement Flag Fire Weapon Stop Turret Yes Poll PIR Sensors Which PIR Sensor? Target Detected? Yes Turn Motors OFF No 1 2 3 Turn Turret Left Turn Turret Right Spin Grover 180o Poll Ultrasonic Sensor Turret Sensor Triggered? No Turn Maxed? No Yes No Stop/Reset Turret Yes Turn 90o Right Turn Motors OFF Obstruction Detected? Spin Grover 90o in Same Direction Turn Motors ON FWD Yes No Engagement Flag Set? Increment Engagement Count on LCD Clear Engagement Flag Project Completion Timeline Week 8 9 Project Completion - Finish PCB layout and fit parts to printout - Receive final O.K. from Chuck SPRING BREAK (Gambling in VEGAS!) 10 - Start mounting parts to PCB - Continue with software prototyping 11 - Start interfacing software with hardware 12 - Finish up on packaging with gun turret and servo motor mount 13 - Finish software interfacing - Begin working on user manual 14 - Finish user manual - Work on demonstration video and final presentation 15 - Final Presentation Questions?