Competitive Inhibition by Aaron M Ard and Jeremy

Competitive Inhibition by Aaron M. Ard and Jeremy W. Skipper December 2, 2004 Aaron Ard and Jeremy Skipper 1

Introduction Three Main Topics • Design Goals and Requirements • Electrical Design • Mechanical Design December 2, 2004 Aaron Ard and Jeremy Skipper 2

Goals and Requirements Goals: • Win Tiger Scramble • Receive an “A” • Provide a basis and example for future participants in EE 4701 Requirements: • Build a working robot • Remain within allocated budget of $500. 00 • Ensure that our robot is the fastest, “smartest”, most efficient, and most reliable December 2, 2004 Aaron Ard and Jeremy Skipper 3

Preliminary Design Primary Systems • Electrical – Boards, Microcontroller, Power, AI, Controls, RF, Sensors • Mechanical – Motors, Gearing, Wheels, Platform, Ball Manipulator, Actuator December 2, 2004 Aaron Ard and Jeremy Skipper 4

Electrical Overview December 2, 2004 Aaron Ard and Jeremy Skipper 5

Microcontrollers Requirement: The microcontroller(s) must provide enough I/O, speed, memory, etc. Solution: Microchip’s 18 F 452 for the main microcontroller and two 18 F 2431’s for motor control December 2, 2004 Aaron Ard and Jeremy Skipper 6

Microcontrollers The main features of each MCU Features Microchip 18 F 452 Microchip 18 F 2431 Max. Clock Frequency (MHz) 40 40 Flash Memory (Bytes) 32768 16384 PWM YES A/D 8/10 -Bit 5/10 -Bit Encoder Interface NO YES Serial Interfaces USART, I 2 C, SPI I/O Pins 34 22 Package 44 -Pin PLCC 28 -Pin DIP December 2, 2004 Aaron Ard and Jeremy Skipper 7

Motors Requirement: The entry must move a minimum of. 12 meters per second. Solution: COPAL 30: 1 DC Gearmotor Image from www. robotcombat. com • • • 6 -12 volts 29 -52 in-oz max torque 390 -770 max rpm 1. 3 A stall current. 78 m/s (w/ chosen tires) December 2, 2004 Aaron Ard and Jeremy Skipper 8

Motor Control • Low level motor control performed by two independent 18 F 2431’s – Quadrature input from encoders – Receive required speed from main MCU – Transmit distance traveled to main MCU • High level motor control performed by the 18 F 452 – Calculate required speed and direction of each motor to arrive at target – Implements “dead reckoning” with distance data from the 18 F 2431’s December 2, 2004 Aaron Ard and Jeremy Skipper 9

Encoders Requirement: The entry must provide feedback on motor performance. Solution: US-Digital S 4 optical rotary quadrature encoder Image from www. usdigital. com December 2, 2004 Aaron Ard and Jeremy Skipper 10

Motor Drivers Requirement: The entry must have the ability to drive two DC motors simultaneously. Solution: Texas Instruments TPIC 0107 B PWM controlled intelligent H-Bridge • 0 -33 V supply voltage • 5 A internal current shutdown • Direction input December 2, 2004 Aaron Ard and Jeremy Skipper 11

RF Communication Requirement: The entry must receive data from the vision system on ball and robot locations. Solution: 433. 92 MHz RF receiver from Parallax provided to each team Image from www. parallax. com December 2, 2004 Aaron Ard and Jeremy Skipper 12

Local Sensors Requirement: The entry must eliminate vision system error, if present. Solution: Sharp GP 2 D 120 IR sensor • Analog voltage corresponding to distance • 4 -30 cm (~12 in) range December 2, 2004 Aaron Ard and Jeremy Skipper Image from www. acroname. com 13

Local Sensors (cont. ) Requirement: The entry must know when the tennis ball is within the capture mechanism. Solution: Two crossing bend (flex) sensors • 4 1/2” x 1/4” in • 75 k-80 kΩ @ 0° • 150 k-200 kΩ @ 90° December 2, 2004 Image from www. imagesco. com Aaron Ard and Jeremy Skipper 14

PCB Board Requirement: The entry must reliably and efficiently connect components together. Solution: 4 -Layer PCB board • Designed in Cadence Capture and Layout • Parts securely soldered in place • 4 -Layer board reduces long and unnecessary traces December 2, 2004 Aaron Ard and Jeremy Skipper 15

Power Requirements: The entry must operate continuously for 15 minutes. Copal motor requires 6 V-12 V for operation. Solution: 9. 6 V 1600 m. Ah Ni-MH rechargeable RC car battery. As shown below, this battery will operate the robot continuously for over an hour. December 2, 2004 Device Current DC Motors 250 m. A Servo 250 m. A PCB Board 100 m. A IR sensor 50 m. A Encoders 20 m. A TOTAL: 670 m. A Aaron Ard and Jeremy Skipper 16

Power (cont. ) Requirement: The entry must provide a regulated 5 V supply for the MCU board and servo. Solution: National Instruments LM 2676 switching regulator • • 3 A current output 94% efficiency ON/OFF pin Available in common TO-220 package December 2, 2004 Aaron Ard and Jeremy Skipper 17

Locomotion Requirement: The entry must have the ability to take the shortest path possible between any two points. Solution: Differential steering will enable the entry to move forward and backward as well as turn in place. December 2, 2004 Aaron Ard and Jeremy Skipper 18

Wheels Requirement: The entry must have wheels with a diameter to complement the gearing of the motor and allow only minimal slip. Solution: Solid rubber wheels with rib pattern • 1 1/2” diameter • 1/16” axle • . 65 oz December 2, 2004 Image from www. robotcombat. com Aaron Ard and Jeremy Skipper 19

Casters Requirement: The entry must stay balanced while moving freely in any direction dictated by the motor-driven wheels. Solution: Omni-directional caster • Omni-directional rotation • 2” diameter • 8 mm axle Image from www. imagesco. com December 2, 2004 Aaron Ard and Jeremy Skipper 20

Base Requirement: The entry must have a base that protects the wheels and allows for the mounting of other hardware. Solution: Custom made aluminum base December 2, 2004 Aaron Ard and Jeremy Skipper 21

Platter Requirement: The entry must have a platter that provides extra space for mounting electronic hardware without the risk of unwanted conduction. Solution: Custom made Plexiglas® platter December 2, 2004 Aaron Ard and Jeremy Skipper 22

Ball Manipulation Requirement: The entry must capture a tennis ball, but continue to allow it to roll freely. Solution: Custom made gripper with actuator December 2, 2004 Aaron Ard and Jeremy Skipper 23

Actuator Requirement: The entry must have an actuator that consumes minimal power in the standby state, operates in under 3 seconds, and takes up minimal space. Solution: Hitec HS-85 BB+ servo • • . 16 sec/60° at no load 240 m. A max current drain 29 x 13 x 30 mm 42 oz-in torque December 2, 2004 Image from www. servocity. com Aaron Ard and Jeremy Skipper 24

General Operation December 2, 2004 Aaron Ard and Jeremy Skipper 25

Preliminary Budget Item Quantity Cost (Each) Total 4” x 6” PCB Board 1 $92. 40 Copal Gearmotors 2 $21. 99 $43. 98 Optical Rotary Shaft Quadrature Encoders 2 $39. 99 $79. 98 Microcontroller 1 $0. 00 TPIC 0107 B H-Bridge 2 $0. 00 Wheels, Tires, Gears, and Misc. Drive-train Parts N/A $65. 00 Misc. Electronics (Caps, Diodes, Regulators, Resistors) N/A $75. 00 Servo 1 $25. 00 Bend Sensors 2 $0. 00 Infrared Distance Sensors 1 $12. 50 $0 $0. 00 Body made of 1/8” Aluminum N/A TOTAL: December 2, 2004 $393. 86 Aaron Ard and Jeremy Skipper 26

Feedback • Questions? • Comments? • Suggestions? Thank you for your time and attentiveness! December 2, 2004 Aaron Ard and Jeremy Skipper 27