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Robot Design and Construction Tips

Robot Design and Construction Tips. Scott McEwen. Overview. Engineering Design Process Subsystems & System Integration Communication & Documentation Design Engineering & Math Examples Construction Tips Materials Fabrication & Safety. Engineering Design Process Importance.

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Robot Design and Construction Tips

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  1. Robot Design and Construction Tips Scott McEwen

  2. Overview • Engineering Design Process • Subsystems & System Integration • Communication & Documentation • Design Engineering & Math Examples • Construction Tips • Materials • Fabrication & Safety

  3. Engineering Design ProcessImportance • Proven process for any design/build project • Every team is required to submit an engineering notebook that documents the process to design, build, and test your robot

  4. Engineering Design ProcessElements • Define the problem • Determine the design specifications • Develop numerous design alternatives • Choose the optimal design • Build and testthe design Ref: http://best.eng.auburn.edu/ -> Participants -> Contest Information -> Team Resources -> Engineering Topics

  5. 1) Define the Problem • Read the Rules thoroughly at www.bestinc.org • The Competition -> Current Game Rules • Participants -> File Manager -> Public Files • Participants -> Contest Information • Password: r1bb0n • Inventory Consumable & Returnable Kits • Research similar problems and designs

  6. 2) Determine the Design Specs Clear guidelines for creating viable designs: • Goals • Score lots of low point items, then score high point items • Requirements • Ability to ascend/descend quickly • Ability to grab various game pieces • Constraints • Must fit in 24” cube and weigh <= 24 lbs

  7. 3) Develop Numerous Design Alternatives • Engineering design = creative process + content knowledge from variety of disciplines • Brainstorming • Multiple Groups of 3-4? 1+ designs/student? • Sketches, notes, logical & physical models • Scoring Tip: Brainstorming Approaches: How well organized and productive was the brainstorming approach used and documented?

  8. 4) Choose the Optimal Design • Weigh and document pros & cons of each design • Analysis of gaming strategies and design elements to achieve goals • Do we have the tools and skills to build it? • Scoring Tip: Analytical Evaluation of Design Alternatives: Use of analytical and mathematical skills in deciding upon and implementing design alternatives

  9. 5) Build and Test the Design • Invest adequate time and specificity prior to this step • Revisit prior design steps as needed • Scoring Tip: Safety Training *and* safety practices followed • Scoring Tip: Support Documentation • Drawings, photos, test results, etc.

  10. Subsystems & System Integration • Drive Platform • Ascend & descend • Speed & position control • Articulated Arm and end effector (grapple) • Rotate leftto right • Extend up & down • Extend in & out • Grip efficiently • Programming

  11. Communication & DocumentationCommunication Best Practices • Communication mediums • Traditional • Social media • SCRUM – Daily stand-up meetings • Other • Resolving disagreements/conflicts • What works for your team?

  12. Communication & DocumentationEngineering Notebook • Document the process used to design, build, and test the robot. • Tell the story of your robot • Documentation is a critical aspect of the Engineering Process. Provides: • Crucial record of the process • Critical info between different groups • Checklist against requirements • Essential information for new people

  13. Communication & DocumentationImportant Dates • Engineering Notebooks are due on Practice Day (Saturday, Oct 20) • Every team MUST submit an Engineering Notebook • If no notebook on Practice Day, your team will NOT be able to compete on Game Day • Notebooks will be returned on Game Day

  14. Design Engineering & MathExamples – Torque • Dimensions and torque • Small Motor • http://content.vexrobotics.com/docs/276-1610-Drawing-Rev1A.pdf • Large Motor • http://content.vexrobotics.com/docs/276-1611-Drawing-Rev1A.pdf • Inch-pounds = amount of torque required to lift a 1 pound weight 1 that is 1 inch from axis of rotation • Computing torque: Torque = Force * Moment Arm • Torque = Weight (pounds) * moment arm (inches) • Total torque = Sum of (weights * moment arms)

  15. Design Engineering & Math Examples – Torque • PVC Pipe @ 0.21 lb/ft • Grapple @ 0.5 lb • Waste Cargo Ball @ 0.4 lb

  16. Design Engineering & Math Examples – Torque • PVC: (2 ft * 0.21 lb/ft) * 1 ft = 0.42 ft-lb • Grapple: 0.5 lb * 2 ft = 1.00 ft-lb • Ball: 0.4 lb * 2 ft = 0.80 ft-lb • Combined: 0.42 + 1.0 + 0.8 = 2.22 ft-lbs • Torque = Weight (pounds) * moment arm (inches)

  17. Design Engineering & Math Examples – Torque • 2.22 ft-lbs = 26.64 in-lbs • Large Motor torque = 23.53 in-lbs • “Back to the drawing board”

  18. Design Engineering & Math Examples – Motor Specs • Futaba S3003 servo • Torque: 2.75 in-lb(44 oz-in) • Gear Type: Plastic • BEST Small Motor • Torque: 9.49 in-lb (152 oz-in) • BEST Large Motor • Torque: 23.53 in-lb (376.48 oz-in)

  19. Design Engineering & Math Examples – Potentiometer (Pot) • Definition. A Pot is an electrical device whose resistance is adjustable. It can be used as an analog sensor to measure angular position of a rotational component, such as a robot arm. The Cortex can use the Pot’s output to control or limit some other component. • Input. Connect Pot’s shaft to a rotational axle or shaft. NOTE: the POT’s total range of motion (i.e., rotation) is 300 degrees. • Output. Connect the Pot’s wiring to a Cortex analog input port. • Operation. As the resistance of the Pot changes, so does the voltage. This varying voltage can be measured by the Cortex and is directly proportional to the angular position of the Pot’s shaft. • Data sheet: http://www.bitechnologies.com/pdfs/p160.pdf • easyC example: https://sites.google.com/site/team3141rx/easyc/arm3 • Wiring example: http://www.education.rec.ri.cmu.edu/classes/cal_u/ar/toolbox/content/curriculum/robotics_systems/home_brew/potentiometer/potentiometer.swf

  20. Construction Tips • Materials • Fabrication & Safety

  21. Materials • Polypropylene Sheet • Aluminum bar, rod, & sheet • Steel all-thread rod • Wood • PVC pipe • Electrical • Fasteners • Miscellaneous

  22. Fabrication & SafetyClub Workshop • Location & Hours • 999 Vallejo Street, east of I-25 and north of 8th Ave • 7 days/week, 9a to 11p M-F; 8a to 11p, Sat & Sun • Cost: • Special RM BEST rate • Call 720-324-7222 for details • Tools • Woodwork Shop, with CNC router • Machine Shop • Metal Shop • Classes • www.clubworkshop.com

  23. Fabrication & SafetyCutting Plastic Sheet (video) Wear eye protection & secure work • Scribe and break – Sturdy knife • Good for 1/8” sheet • Jig saw – New blade, 10 teeth/inch • Band saw – ½-wide blade, 14 teeth/inch • May cause melting • Circular saw – Carbide tip, triple-chip • Plywood blade will cause melting • Table saw – 60-80 teeth, triple-chip, 1/8 to ½ inch blade exposed

  24. Fabrication & SafetyCutting Aluminum Bar & Rod Wear eye protection & secure work • ½-inch Bar • Hacksaw: laborious and slow • Jig saw: (see notes) • Band saw: wood-cutting blade • Horizontal band saw: • straight & safe • Visit Club Workshop

  25. Fabrication & SafetyCutting Aluminum Sheet • Tin Snips: laborious • Stop short of full cut to avoid cut marks • Air or power shears • Sheet metal shear • Visit Club Workshop • For marking, use ultrafine Sharpie • After cutting, dress edges with file

  26. Fabrication & SafetyBending Aluminum Sheet • Hand bender • Vise • Sheet metal brake • Visit Club Workshop

  27. Fabrication & SafetyPVC and Wood • PVC • Hacksaw • PVC cutter • Wood: Holes & round parts • Drill • Drill press • Hole saw

  28. Fabrication & SafetyDrill Press Speeds (rpm) Wear eye protection & secure work Circle cutters: Drill 1st side, flip material over, finish on 2nd side

  29. Fabrication & Safety Wear eye protection & secure work • Center punch holes to prevent drill from wandering • Clamp work

  30. Fabrication & SafetyFasteners– Drill and Tap • Threads are cut inside a hole using a tap • Match hole size (numbered drill bit) to screw • Screws: size – threads/inch • Purchase drill/tap sets at Ace Hardware

  31. Fabrication & SafetyElectrical Components Proper connection of electrical components Mount Cortexfor easy access

  32. Fabrication & SafetyLimit Switches Mini Snap SubMini Snap Connect to digital port Closed = “0” Open = “1”

  33. Fabrication & SafetyVEX Motor Mounting Kit • Specifically designed to mount BEST motors • Flat, but designed to be easily bent

  34. Fabrication & SafetyBEST References • http://best.eng.auburn.edu/b_game_rules.php • http://best.eng.auburn.edu/stored_procedures/folder-manager/ • 2012 BEST Consumable Kit List • 2012 BEST Returnable Kit List • BEST Large Motor Spec Sheet • BEST Small Motor Spec Sheet • BEST Generic Kit Usage Guide • 3.X VEXnet Firmware Upgrade Utility Operating Instructions and Installation • Cortex Microcontroller and VEXnet Joystick User Guide • VEX Cortex Pin-out • Introduction to easyC & Cortex (Intelitek) • Google for PDF: “Tools, Tips and Materials” by David Kwast

  35. Club Workshop • Location & Hours • 999 Vallejo Street, east of I-25 and north of 8th Ave • 7 days/week, 9a to 11p M-F; 8a to 11p, Sat & Sun • Cost: • Special RM BEST rate • Call 720-324-7222 for details • Tools • Woodwork Shop, with CNC router • Machine Shop • Metal Shop • Classes • www.clubworkshop.com

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