1. NXT Robotics Techniques Workshop 3 - 2010 “Opening doors to the worlds of science and technology for Oregon’s youth” 6/10/2010NXT Robotics Techniques - 20101

2. AGENDA General Robot Design Navigation Design Robot Characterization Efficient Programming Distance Sensor Buoy Mission Resources Contacts Next Steps 6/10/2010NXT Robotics Techniques - 20102

3. General Robot Design Robot balance – Pick up the 3 motor robot – Where is the center of gravity? keep CG vertical force inside wheelbase Smart Move Incline mission – what happens to CG? What happens with acceleration? Starting torque lifts front end up with rear wheel drive Wheels – small, large, treads, skids, swivel – positives & negatives of each - examples Gears – bevel, straight, worm, pulley – torque transfer - examples Beam & Pin structural design - examples Screen & control panel location Battery Access Mission Attachments – examples: fork lift, cow catcher Questions on general design? 6/10/2010NXT Robotics Techniques - 20103

4. Navigation Design Sensors – Why do we use sensors? – navigation – How do we use sensors? – examples: Light - stop on line Touch? Rotation? Distance? – Problems programming sensors Programming Tutorial, link on resource slide – have your team review Learn sensor’s useful range – distance sensor min-max range – rotation sensor angle – light sensor height, mounting angle, shading, robot speed – Light sensor green/black exercise, reflected light value, light threshold Read values from programming blocks, lower left corner 6/10/2010NXT Robotics Techniques - 20104

5. Navigation Design Mission example: – Pick up buoy, place in box – park robot with light sensor on line – We will do this mission later in class – What kinds of navigation would you use on this mission? LAB: brainstorm ideas 1 2 3 6/10/2010NXT Robotics Techniques - 20105

6. Navigation Errors Straight move – what errors could result? – Linear error – buoy dropped in front of box – Angular error – buoy dropped to left or right of the box Test example: move 24 inches from starting point – Find pointer in kit, add to robot cow catcher – Draw line on paper where pointer stops – Repeat 5 times 6/10/2010NXT Robotics Techniques - 20106

7. Robot Characterization 6/10/2010NXT Robotics Techniques - 20107 Add position and measurement guides to cow-catcher

8. Robot Characterization Write simple test program to make robot go forward 24” – record linear & angular results – LAB: Run this characterization now on your table Use blue tape for start line and paper for landing point 6/10/2010NXT Robotics Techniques - 20108

9. Robot Characterization (field prep) Starting line with tick marks to align robot Graph paper at ending location to mark robot stopping position 6/10/2010NXT Robotics Techniques - 20109

10. Robot Characterization (collect data) Use measurement guide and program on previous slides Run tests for 5-10 times Draw line on paper after each run 6/10/2010NXT Robotics Techniques - 201010

11. Robot Characterization (Analyze Data) Draw bounding box around min and max data points, 0.28” X and 1.9” Y in this example from a workshop robot Identify min and max stopping angle 6/10/2010NXT Robotics Techniques - 201011

12. Navigation Influences 1.Starting blocks – base position – base calibration - example 2.Speed and robot bounce – Why? 3.Battery charge – Why? 4.Move Block steering left-right 5.Tire size and third wheel position 6.Weight & balance 7.Rotation sensor in motors – 1 degree resolution 8.Gear slop 9.Software inside NXT – Slow one wheel down, the other slows – Result is S curve tracking We can control 1-6 but not 7,8,9 Determine when to use dead reckoning vs. navigation Use sensors and attachments to compensate for navigational errors Examples: wide fork with long tines for buoy mission, back into wall for alignment Don’t waste time debugging long, dead reckoning moves! 6/10/2010NXT Robotics Techniques - 201012

13. Robot Characterization (next steps) Run same experiments at various power settings Run L-tests, inclined plane, other short missions Use touch sensor to move around an object Run mission tests when the Body Forward challenge is available – Your team will want to dive in and program all missions – decide which missions to do, then characterize appropriate missions – Keep a good lab notebook 6/10/2010NXT Robotics Techniques - 201013

14. Robot Characterization (Questions) Characterize your robot then discuss with your team: Did robot move expected distance? Why not? What would worst case errors to be? How do angular errors affect performance? Are there ways to reduce the errors? How can we work around the errors to achieve mission success? 1. 2. 3. Questions on characterization? 6/10/2010NXT Robotics Techniques - 201014

15. Efficient Programming Firmware & programs stored in flash ~ 125KB – Each program ~ 0.1 KB overhead – Move block ~ 5.1 KB, two ~5.8KB To determine memory usage – Lower right corner – click NXT Window, Memory 6/10/2010NXT Robotics Techniques - 201015

16. Efficient Programming Loops, My Blocks – Create a program to move in a straight line then turn 90 degrees Do this 4 times to create a square (square1 program) – How can we change the program to make it more efficient? Use a loop and execute move-then-turn – 4 times (LoopSquare program) Check memory size, write down value 6/10/2010NXT Robotics Techniques - 201016

17. Efficient Programming Create a My Block – Add a Move block, a Wait for light sensor block, and a Move block Set the first Move block to Duration: unlimited, and 50 % power Set the Orange Wait for Light Sensor to “less than” value of 45 Set the second Move block to stop – Select all 3 blocks - hold shift key and click all blocks – Click Edit – Make A New My Block – Add a title in upper right corner, click Finish – Download and test your “Wait for Light Sensor” My Block in a program – Save your My Block for later use in Buoy Mission – LAB: do this now 6/10/2010NXT Robotics Techniques - 201017

18. Efficient Programming Show “light sensor” My Block with move-wait- move Create a program with 3 “light sensor” My Blocks – Download the program to NXT – Check NXT memory usage Create a program with 9 blocks – (use move-wait-move etc.) – Check NXT memory usage – Is the My Block more efficient? 6/10/2010NXT Robotics Techniques - 201018

19. Efficient Programming Show program MyBlockLightSensor My Block uses? – Code reuse – subroutines – Move/turn – Stop on black, stop on color (use a variable to control the value of the light sensor) – Line follow, left or right – 3 rd motor activity – raise, lower fork 6/10/2010NXT Robotics Techniques - 201019

20. Efficient Programming Printing your program – Print out your program using “file” “print” to “html file” – This action produces html and png files. You can use the png file in your program documentation – Printed programs are a requirement for tournament judging Questions on programming? 6/10/2010NXT Robotics Techniques - 201020

21. Distance Sensor – Add a “Wait for Distance” block – Program the robot to stop at 4 inches – LAB: do this now – This is the last sensor you will learn 1.Rotation 2.Touch 3.Light 4.Distance 6/10/2010NXT Robotics Techniques - 201021

22. Mission Example: Buoy Start with the robot on blue line #1 Move forward and pick up the buoy Deliver the buoy into box #2 at the end of the field End the mission with the robot parked with the light sensor on blue line #3 Questions on the Buoy Mission? LAB: do this now 6/10/2010NXT Robotics Techniques - 201022

23. Mission Example: Buoy 6/10/2010NXT Robotics Techniques - 201023 s Start here End here Place buoy here

24. Resources Tutorial, Dale Yocum – Run tutorial: www.ortop.org/NXT_Tutorial/ – Requires Adobe Macromedia Shockwave player and high speed connection http://nxtprograms.com/index1.html – look for “castor bot” – contributed to Workshop 3 motor design Http://www.hightechkids.org/coach-library – the Wiki of LEGO Robotics Robot Characterization, Dale Jordan – www.ortop.org/Workshops - look in Workshop 3 materials www.ortop.org/Workshops Building Robots with LEGO Mindstorms NXT – Authors: Ferrari, Ferrari, Astollo 6/10/2010NXT Robotics Techniques - 201024

25. Contacts Cathy Swider – ORTOP & FLL Operational Partner for Oregon – cathy_swider@ous.edu – 503-725-2920 cathy_swider@ous.edu Jim Ryan – james.r.ryan@intel.com – 971-215-6087 james.r.ryan@intel.com Roger Swanson – swanson@hevanet.com – 503-297-1824 swanson@hevanet.com Dale Jordan – dale.a.jordan@msn.com -503-805-9860 dale.a.jordan@msn.com Ken Cone – kcone@hevanet.com – 503-415-1465 kcone@hevanet.com 6/10/2010NXT Robotics Techniques - 201025

26. Next Steps Register your team with FLL Share with your team – These slides – Mindstorms NXT Programming Tutorial By Dale Yocum – www.ortop.org/NXT_tutorialwww.ortop.org/NXT_tutorial – Build 2-3 test robot designs, then have your team select a hybrid of best features – Challenge the kids Make up your own exercises stress basics take good lab notes 6/10/2010NXT Robotics Techniques - 201026

27. Parting thoughts From “All I really need to know (about creative thinking) I learned by studying how children learn in Kindergarten.” – Start simple – Work on things that you like – If you have no clue what to do, fiddle around – Don’t be afraid to experiment – Find a friend to work with, share ideas – It’s OK to copy stuff (to give you an idea) – Keep your ideas in a sketch book – Build, take apart, rebuild – Lots of things can go wrong, stuck with it! Credit MIT 6/10/2010NXT Robotics Techniques - 201027

28. Review & Questions Please give us your input – visit ortop.org/fll or email: questions@ortop.org – Let ORTOP know how we can improve the program – Thanks for volunteering! Your efforts make learning possible – Disassemble robots BUT keep the following together: Castor mount (pages 11-18) Light sensors (pages 24-27) Touch sensor (pages 28-29) Ultra-sonic sensor (pages 30-31) Cowcatcher (pages 32-33) Fork lift (pages 34-35) 6/10/2010NXT Robotics Techniques - 201028

29. Alternative Measurement Guide 6/10/2010NXT Robotics Techniques - 201029

30. 2010 Workshops Survey 6/10/2010NXT Robotics Techniques - 201030 List 3 things or experiences you remember from the three workshops What was the most fun? What was the least fun? What should be changed? Other comments? Please turn in you surveys Thanks for participating in FLL!