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Autonomously Controlled Front Loader By: Steve Koopman and Jerred Peterson Advisor: Dr. Schertz Presentation Outline Project Introduction Hardware Design Software Design Final Progress Future Work Conclusion Questions Presentation Outline Project Introduction Hardware Design Software Design Final Progress Future Work Conclusion Questions Project Introduction Project Motivation Work towards a fully automated system, such as a gravel yard Investigate small-scale operation of autonomous vehicle Can model several interacting robots cheaply, without risk of damage Allows work to be done towards full-scale operation Starting point for additional small autonomous vehicles Project Introduction Specific Project Goals Modify toy vehicle to do simple tasks Load a bucket with material Dump material into truck Repeat until the truck is full Vehicle operates autonomously Low cost vehicle design Flexible design for future expansion Project Introduction Project Goals for Tasks Rotate vehicle until loading bin located Line up with bin, drive to it Lower bucket and load material Raise bucket and leave bin Rotate until truck located, line up with the truck Drive to truck, dump material into it Repeat process until truck full Project Introduction System Block Diagram Repositions Bucket and Arm Moves and Rotates Vehicle Real World Environment Ultrasonic Sensor Infrared Detector Compass Object Distance Target Detection Heading Information Microprocessor Arm and Bucket Position Arm/Bucket Control Circuitry Track Control Circuitry Arm/Bucket Motors Track Motors Arm/Bucket Position Sensors Infrared Encoders Distance Traveled Measurements Presentation Outline Project Introduction Hardware Design Software Design Final Progress Future Work Conclusion Questions Hardware Design Design Steps Vehicle Choice Sensor Choice Circuitry Design Circuit Board Construction Microcontroller Interfacing Hardware Design Vehicle Choice Hobby Kit Vehicle (Tamiya hobby kit) Bobcat RC Vehicle (Bobcat T190) 2 drive motors, arm raise motor Easier to expand Weak lifting capacity 2 drive motors, arm raise motor, bucket dump motor Internal limit switches Harder to modify Continued with Bobcat Vehicle Hardware Design Sensor Choice SRF05 Ultrasonic Sensor for Distance Measurement Can operate down to ~1 inch Used in previous projects PNZ109L-ND Infrared (IR) Transistor for Object Detector Detects IR LED at ~5 feet away Little issue with stray IR interference Hardware Design Sensor Choice Vector V2x Compass for Heading Information ~1 degree resolution Serial output 10 Hz update rate Continuous sample mode Hardware Design Sensor Choice HOA0149-1 IR reflector/emitter for Rotary Encoder Small size Good signal result Rotary Encoder Wheel Pattern 8 pulses per revolution Mounted directly to drive wheel Hardware Design Hardware Design Circuit Design Motor Circuitry Quadruple Half H-bridge L293 chips High Current output for motors About 3W power dissipation on chip Logic circuitry Easier microcontroller interface Protects bucket and arm motor Hardware Design Circuit Design Infrared Sensors Infrared transistor Op-amps increase transistor distance Schmitt-trigger to reduce noise Infrared Encoder Bias circuitry for normal operation Schmitt-trigger to reduce noise Hardware Design Circuit Board Construction Perforation board used for flexibility 2 circuit boards Compass board to hold digital compass Main circuit board for rest of circuitry Surface mount sockets hold Integrated Circuits (IC’s) Wire-wrap and Soldering used for circuit construction Hardware Design Circuit Board Construction Terminal Strip used for power connection Single and Double Pin Headers for external connections Single pin headers connect to motors and sensors Double pin header connects to microcontroller and compass board to main circuit board Hardware Design Circuit Board Construction Circuit Board Layouts Main Circuit Board IR Rec Opamp IR Encod IR Encod SchmittTrigger And Chip H-Bridge mtr mtr 2.5" Not Chip m sens 3V to 5V Buffer Component m sens 2.5" 3V to 5V Buffer Component mtr And Chip 3V to 5V Buffer Main Board Connection H-Bridge mtr Opamp Compass Circuit Board Compass (Must be on separate board, to mount level to ground) Ultrasonic 3V to 5V Buffer 50 Pin Micro Header 5v Reg Compass Connection + Batt - 4" 3.7" Presentation Outline Project Introduction Hardware Design Software Design Final Progress Future Work Conclusion Questions Software Design Software Block Diagram Microcontroller Features Software Setup Low Level Task Breakdown Software Design Software Block Diagram Software Design Microcontroller: 8051F340 Development Kit Similar Operation as EMAC board Features: 48 million instructions per second (MIPS) Four independent timers (T0 through T3) Five Programmable Counter Arrays (PCA0 through PCA4) One Serial Peripheral Interface (SPI0) Two external Interrupts (EX0 and EX1) Etc. Software Design Software Setup: Handle sensor reading in interrupts Write low level functions for basic operations Make functions to do complicated tasks i.e. locate IR beacon, load bucket, dump bucket Software Design Low Level Tasks: Distance Measurement Ultrasonic sensor Can operate up to 20 Hz Small counting loop in Timer 2 Also used as 50 ms timing source Needs 10 us on pulse to start Small delay loop in Timer 2 Measure time return signal is high PCA2 interrupt triggered on edge transition Handles microsecond to cm conversion Sets new distance measurement flag Software Design Low Level Tasks: Rotary Encoders Uses EX0 and EX1 for interrupts Encoder period calculated based off Timer 2 Velocity Controller Variable period update rates Simple proportional controller used Proportional-Integral (PI) controller did not work Low resolution encoder Possible initial condition problems Oscillations noticed with small gain Software Design Low Level Tasks: Infrared Beacon External Reset Button: Manually read in software Use PCA3 as interrupt Interrupt triggers software reset Compass Function to control enable/disable of compass SPI0 handles data reception Code reconstructs information, sets new compass reading flag Software Design Low Level Tasks: Variable Track Drive Speed: Function calls set motor directions and duty cycles PCA’s generate Pulse Width Modulated (PWM) signals Set PCA timer for 1 kHz frequency Best frequency found for drive motors Used for 1 ms timing source Use PCA0 and PCA1 for PWM generation Software Design Low Level Tasks: Arm and Bucket control: Rotate vehicle to heading Function sets motors to move correct direction Reads corresponding sensor until pressed Rotate fastest direction to reach the desired heading Turn slightly when near desired heading until facing the right way Remaining tasks: Make routines using these basic functions plus sensor information Presentation Outline Project Introduction Hardware Design Software Design Final Progress Future Work Conclusion Questions Final Progress Sensors testing completed All sensors interface to microcontroller Sensors work as desired Exceptions: Ultrasonic and IR transistor when blocked by bucket Compass when arm is near fully raised Motor drive electronics work Microcontroller successfully controls speed and direction Heat sink added to drive circuitry to prevent overheating Final Progress Vehicle operates mostly autonomously Can navigate between truck and load Loads bucket and dumps properly usually Small bug in location routine that causes long delay when IR beacon too far away Lining up with truck is difficult due to IR beacon spread Vehicle repeats task until stopped Final Progress Small project difficulties IR beacons not easy to differentiate at long ranges IR beacon gives wide detection angle, and not easy to track Compass/software sometimes gives wrong orientation Causes alignment with bin and truck to be off Unknown reason for this problem Vehicle operation becomes somewhat random with low batteries Presentation Outline Project Introduction Hardware Design Software Design Final Progress Future Work Conclusion Questions Future Work Add camera and computer interface Image processing system next step in system Necessary for full scale operation Create additional autonomous vehicles Allow cooperative interactions between vehicles Could do tasks like operate truck, fill bin, etc. Future Work Replace/Upgrade Infrared Transistors Work on Compass/Microcontroller interface Difficulty tracking infrared beacons Infrared beacon period varies with distance Determine why compass gives wrong direction readings Replace compass with newer model if necessary Better Battery and Charger Improve operation time of vehicle Increase linear range of drive motors Decrease chance of overcharging battery Future Work Improve Rotary Encoder Resolution Model Track motor and Gear Train Allows better velocity controller routine Minor hardware changes Better measurement of linear/rotational velocity Active low drive signals, change ultrasonic and IR beacon, make secure board mount in vehicle, etc. Create testing station with interface Battery-free operation, receive debug Presentation Outline Project Introduction Hardware Design Software Design Final Progress Future Work Conclusion Questions Conclusions Small scale autonomous robot works Bucket can be loaded without special sensors Need changes to system if full scale implementation desired Detect full bucket by period of rotary encoders increasing past threshold Detect nearing wall by consecutive equal distance readings More work to be done with project Full scale implementation would need image processing More robots needed for automating an entire system Conclusions Vehicle Testing Area Conclusions Vehicle Operation Conclusions Special Thanks To: Nick Schmidt for help with hardware construction and modification Dr. Donald Schertz for project advising, and help with microcontroller problems Dr. Malinowski for help with using microcontroller Chris Mattus for ordering parts, and printing poster board The rest of the EE faculty for feedback about our project Presentation Outline Project Introduction Hardware Design Software Design Final Progress Future Work Conclusion Questions Questions Any Questions??? Backup Material 50 Pin Header 3.3 to 5V buffer connections “Motor” connector “sensor” connector