1. EE4701 Preliminary Design Presentation Ben Maderazo Justin Smith

2. Presentation Goals Present our own requirements analysis and design decisions for critique Defend our decisions and explain why our design will perform better than others Prove that we are ready to begin assembling and testing our robot for competition

3. Team Goals Apply KISS principle in hardware implementation to save time Spend more time on algorithm development and application than hardware Win competition

4. Competition Rules Each robot must fit within a twelve inch cube Each match will be the best of three rounds with each round lasting no longer than fifteen minutes The ball may be captured, pushed, or kicked into the goal Robot and ball position will be monitored by an overhead camera To enter into the competition, each robot must pass preliminary qualification tests

5. Preliminary Qualifications Robot must travel from one goal to other and back in less than two minutes The robot must capture a ball and return it to the home goal in under five minutes The robot must retrieve three balls, one at a time, and return them to its home goal in fifteen minutes while avoiding an immobile obstruction

6. Robot Subsystems Information processing Obstacle detection Locomotion RF reception Ball capture Power

7. Information Processing Subsystem Must take data from other subsystems, process it, and issue commands.

8. Analysis Speed Must be done 10x per second Mathematical Computation Addition, subtraction, and absolute value Arc tangent Function# of TimesInstructions Calculate relative distance510 Check current score115 Check if target ball has moved110 Check if robot is at destination12 Misc.165 Total~150

9. Requirements 3 input ports for switches 2 A/D converter ports for IR sensors. 2 PWM output ports for H-Bridge. Ability to send and receive 4 serial transmissions. Ability to compute basic math and binary operations. Ability to compute the arc tan function. Ability to use interrupts.

10. OOPIC Advantages Virtual Circuits Interrupts Object Oriented Programming Predefined objects Unlimited serial ports Disadvantages Slower than the PIC

11. Math Coprocessor PAK-II Features  Communicates Serially  20Mhz  Performs sin, cos, tan, inverse functions, square roots, powers, and many other functions

12. Schematics

13. Obstacle Detection Subsystem The robot will need to detect objects in its path to pass the second round of qualifying. It is not certain if this will be used during the contest.

14. Analysis Distance Requirements Robot travels at max 2 ft/s Estimate.5s for robot to stop after detection.5s x 2 ft/s =.5 ft

15. IR Detector Advantages Long Distance  ~4” to 3’ Disadvantages Higher power  Ability to test at set times to save power

16. RF Reception RF Reception will be used to receive data and instructions from the Vision System. The part will be supplied by Bryan Audiffred and there will be little room for design in this subsystem.

17. Ball Capture The robot will be required to capture a ball, know if the capture was successful, and secure it.

18. Requirements Can only control one ball at a time Must be able to effectively capture and release balls Must be able to provide feedback of success or failure

19. Hardware choice Construct a housing on the robot chassis that will encase the ball Use a generic servomotor to close a gate at the entrance of the housing Interior is lined with material to reduce inertia of the tennis ball IR emitter, receiver pair on sides of the housing to determine if ball captured

20. Locomotion Subsystem Fetching a ball and returning that ball to a goal requires some type of locomotion. Locomotion involves steering, a propagation system, equipment to drive the propagation, and control circuitry to operate the equipment.

21. Minimum Requirements Speed of at least 0.14 feet per second. Ability to alter the heading and direction of travel. Ability to stop.

22. Locomotion: Introduction to Steering To compete well in the 6’ x 8’ area, robots will need a tight turning radius. The chassis configuration must also be taken into account when analyzing the problem of steering.

23. Locomotion: Steering Analysis Robot must be able to rotate 360° without changing its position Robot must be able to rotate a minimum of 3° at a time

24. Locomotion: Steering Hardware Differential steering system 2 Wheels driven by two separate motors and 2 casters for support Use formula V i / R t = V o / (R t +D) and derivations to calculate velocities and turning radii

25. Steering Hardware Continued Tires: ‘Lite Flite’ Foam tires have a 3” diameter and are made of a foam rubber compound

26. Chassis Schematics

27. Locomotion: Introduction to Motor Drives the propagation and steering systems A good balance of power and precision is desired Efficiency considerations must be taken into account

28. Locomotion: Motor Requirements To be competitive with other robots, we want our robot to travel an average of 1 foot/second. To achieve this speed with our 3” wheels, only around 100 rpms are needed. However, to account for friction, the motor can be geared down to increase the torque.

29. Locomotion: Motor Hardware 2 Mabuchi FA-130RA-2270 motors with Tamiya 70097 Dual Motor Gear box The gear box has ratios of 58:1 and 203:1 The motor has an operating range of 1.5-3.0 volts The stall current is 2 amps

30. Motor Hardware Continued At max efficiency, the speed is 6990 rpms. Using the 58:1 gear setting and 3” wheels, the projected speed is 1.6 feet per second. Our goal of 1 foot per second is easily accomplished with this motor and gearbox combo.

31. Motor Schematic

32. Locomotion: Introduction to Motor Driver External circuitry is needed to interface the motors with the mcu This circuitry helps the motors run efficiently and safely Allows motor to operate at various RPMs as well as forward and reverse

33. Locomotion: Motor Drive Requirements Drive two motors simultaneously Must be able to output from 1.5 to 3 volts Must be able to output up to 2 amps per motor at stall torque

34. Locomotion: Motor Driver Hardware Lynxmotion Dual H-bridge All that is needed is to hook up mcu input lines, motor output lines, motor power supply, and 5V Vcc

35. Power: Introduction Power efficiency much more crucial in battery powered devices Batteries can add significant weight Robot will need adequate voltage and amp output Need batteries to power MCU and motor

36. Power: Requirements H-bridge we chose requires 6 volts to drive the motor and max of 4 amps if both motors stall MCU must have voltage regulated to 5 volts Robot must compete in an undetermined number of matches so rechargeable or extra batteries may be needed

37. Power: Hardware 2 prepackaged Rechargeable Nickel Metal Hydride battery packs Smart charger 9V battery with a voltage regulator for MCU

38. Power: Hardware continued Maximum 30 amp discharge rate. As high as 3000mah capacity nickel metal hydride.All cells are matched. No cell memory, you can recharge the pack without fully discharging Voltage: 9.6 volts

39. Power: Hardware continued 2000ma constant output current for any voltage battery pack Charging current will reduce to trickle charging at 50mah when battery pack close to full, then green LED will be on For 3000 mAh battery pack, charging time is about 90 minutes

40. Battery Packs and Smart Charger

41. Budget OOPIC IC $26.00 Pak-II$30.00 IR transmitter $1.00 IR receiver$1.00 GP2D12 IR Ranging Module$18.95 Twin Motor Gearbox Kit $15.95 Standard Futaba Servo $15.00 Ball Casters$8.95 3" Lite Flite Wheels$4.75 Chassis$30.00 Lynxmotion H-Bridge $25.00 Battery Pack$30.00 PCB Board $100.00 ________________________________________________________________ Total Price $307.00

42. Main Process