FLL Advanced Programming & Best Practices Workshop

Transcription

1 FLL Advanced Programming & Best Practices Workshop Bill Aucoin Maryland State FLL Committee University of Maryland, Baltimore County (UMBC) October 5, 2013

2 Guidelines For Today Feel free to enter and leave at any time quietly The toilets are out the back of the auditorium and to the right This is intended to be a facilitated discussion, not a one-way lecture Group participation is expected at all times! This discussion is intended to stand alone We apologize if some of the topics you have heard already The target audience is all types of coaches: rookie to expert We will avoid specific discussions of this year s challenge and strategies for each mission Feel free to discuss that outside of this clinic 3

3 Introductions and Administrivia

4 Don t Be Worried If You Feel That You Don t Know Everything About FLL and Robotics! We are a team. We do the work to find solutions with guidance from our coaches and mentors. We know our coaches and mentors don't have all the answers; we learn together. We honor the spirit of friendly competition. What we discover is more important than what we win. We share our experiences with others. We display Gracious Professionalism and Coopertition in everything we do. We have FUN!

5 In The Spirit Of Coopertition, Please Consider Helping Other Teams Coopertition is displaying unqualified kindness and respect in the face of fierce competition Coopertition is founded on the concept and a philosophy that teams can and should help and cooperate with each other even as they compete Coopertition involves learning from teammates It is teaching teammates It is learning from mentors And it is managing and being managed Coopertition means competing always, but assisting and enabling others when you can 8

6 If You Are A Beginning Team, Be Comfortable With How Far You Team Can Go Regional Qualifier! We are a team. The topics we discuss today might be We something do the work thing to you find are solutions already with doing, guidance something from you our coaches can do this and year, mentors. something you should try next year We know our coaches and mentors don't have all the answers; we learn together. You make the choice! We honor the spirit of friendly competition. State Tournament!! What we discover is more important than what we win. We share our experiences with others. World Festival!!! 9 We display Gracious Professionalism and Coopertition in everything we do. We have FUN!

7 It Is Up To The Individual Coaches On How To Teach/Apply These Ideas With Their Teams Please try to make FLL a learning experience for your teams! 10

8 Agenda Start End Topic 1:00 PM 3:00 PM FLL Advanced Programming and Best Practices 3:00 PM??? Open Questions and Answers Topics Sensors (including Wait For Blocks and Sensor Calibration) Program Flow Control (including Loops and Switch Blocks) MyBlocks Moving and Turning (including Motor Blocks and Move Blocks) Squaring Up Commenting and Printing Your Programs Master Programs or Sequencers Base Operations (including Starting Positions and Attachments) Motor Reset Blocks Multiple Sequence Beams Data Wires (including Constants, Variables) Line Following Generic Tips and Recommendations Other References (Books, Websites, etc.)

9 Sensors (including Wait For Blocks and Sensor Calibration)

10 Cougar Robotics Has Offered What They Consider To Be A Better Way To Wait For Sensor 04 WaitForDark.rbt Author: RobotBillMD Revision: 03 Required Sensors: Port 3 - Light Sensor This program drives forward until it detects a black line. 05-WaitForDark.rbt Author: RobotBillMD Revision: 05 Required Sensors: Port 3 - Light Sensor This program drives forward until it detects a black line. It checks for the line continually (every 6 degrees) vs. continuously. Credits: This program is adapted from the program provided by Cougar Robotics y&layout=blog&id=78&itemid=118 Give these a try to see which of these programming styles work better for you 13

11 Wait For NXT Buttons: Can Be Used For Operator Interaction

12 Back To Agenda

13 Program Flow Control (including Loops and Switch Blocks)

14 Repeated Code Execution Loop Blocks

15 Loop Block: Commonly Used When Executing Portions Of Code When Waiting For A Condition

16 Loop Block: The Loop Will Run Continuously Until The Selected Condition Is Met

17 Here Is A Way To Ramp Up Your Speed Use the value of the loop counter to control the motor power 20

18 Conditional Program Execution Switch Blocks

19 Switch Block: Executes Different Sequence Beams Depending On A Condition/Sensor

20 You Can Nest Switch Blocks For Extra Logic 23

21 You Can Use Data Wires And Values To Control The Switch Block Note: This would NOT work since I never connected the sensor to the switch block! Oops Three Values and the default condition is 2 (value = 20) Add or remove conditions 24 Flat view turned off Set default button

22 Back To Agenda

23 MyBlocks

24 My Blocks Can Be Used To Combine Common Sections Of Code Which Is Repeated

25 One Of The Best References On My Blocks Is Online at

26 Ensure You Know The Issues Associated With MyBlocks When Using Them When you edit a MyBlock, you can affect every program that uses that MyBlock You need to re-download each program that uses the MyBlock to the robot to ensure each program is refreshed Downloading the MyBlock does not update the robot Deleting or renaming a MyBlock will break any program that uses the MyBlock You need to edit each program that uses the MyBlock with the newly renamed Block A program and all of the MyBlocks it uses share the same list of variables Only one copy of a specific MyBlock can run at the same time If you need to run the same MyBlock concurrently, copy the MyBlock and give it a different name 29

27 MyBlocks Are Stored In Their Own Folder Moving a file to a different folder with break any program that is using that block Use Pack and Go to transfer programs 30

28 MyBlocks Can Be Broken A MyBlock will be broken if it has two data plugs with the same name A MyBlock will be broken if it uses data wires and there is a problem with the data wire connections 31

29 Back To Agenda

30 Moving and Turning (including Motor Blocks and Move Blocks)

31 Differences Between Move and Motor Blocks Number of motors controlled Move Block 1, 2 or 3 Motor Block Only 1 motor per block Motor Synchronization? Synchronization & Steering * Block to Block Error Correction? Motor Power Control? Motor Action Block to Block Error Correction None None Block to Block Error Correction If selected, power control will increase/decrease power to maintain desired motor rotation Ramp Up Ramp Down Constant Only if the duration is degrees or rotations * If you choose to control two motors (Example: B & C), the motors will be synchronized * If you select three motors, motors B & C will be synchronized 34

32 For More Reliable Movements, Use Either Locked-Wheel Turns or Move Blocks With -100,0 or +100 Steering Commands Recommendations Tip Based on this battery-voltage experiment, we came up with the following recommendation for FLL teams when using NXT Software to program their LEGO NXT robots: Whenever you use the MOVE block to control your robot, ensure both drive motors maintain the same power level (e.g. only use steering values of -100, 0, or +100)

33 Basic Robot Maneuverability Move Blocks and Motor Blocks

34 Differences Between Move and Motor Blocks Number of motors controlled Move Block 1, 2 or 3 Motor Block Only 1 motor per block Motor Synchronization? Synchronization & Steering * Block to Block Error Correction? Motor Power Control? Motor Action Block to Block Error Correction None None Block to Block Error Correction If selected, power control will increase/decrease power to maintain desired motor rotation Ramp Up Ramp Down Constant Only if the duration is degrees or rotations * If you choose to control two motors (Example: B & C), the motors will be synchronized * If you select three motors, motors B & C will be synchronized 41

35 Carnegie Mellon University Provides A Summary Of The Advantages & Disadvantages Of Each %20vs.%20Move%20Blocks.pdf 42

36 Other Move and Motor Block Considerations Motor Blocks with its Next Action Parameter set to Constant will apply the specified power level throughout the motion of the motor A Move Block will decrease the power near the end of the motion (so it does not overshoot the requested duration) A move block is similar to a Constant Motor Block for most of the duration followed by a Ramp Down Motor Block in this sense 43

37 Basic Robot Maneuverability Driving Straight

38 What Are Some Considerations For Making The Robot Move Straight? Matched wheels Same diameter? How To Make Your FLL Robot Go Straight on YouTube TheFLLCoach (Vienna Robotics) Matched motors Programming Move vs. motor blocks Wheel slippage Friction control Programming correct/varying power levels Using external items 45 Line following with a sensor Wall following by running along wall

39 Sometimes Features Are Used To Ride Along The Table Wall Picture courtesy of Marco Ciavolino Be careful of the mounting location(s), because the robot might have a difficult time maneuvering away from the wall 46

40 Basic Robot Maneuverability Robot Turns

41 For More Reliable Movements, Use Either Locked-Wheel Turns or Move Blocks With -100,0 or +100 Steering Commands Recommendations Based on this battery-voltage experiment, we came up with the following recommendation for FLL teams when using NXT Software to program their LEGO NXT robots: 48 Whenever you use the MOVE block to control your robot, ensure both drive motors maintain the same power level (e.g. only use steering values of -100, 0, or +100). Tip Experiment with different types of turns and see which one is more reliable for you!

42 Basic Robot Maneuverability am I there yet?

43 Smooth Running by Dave Parker 50

44 Basic Robot Maneuverability Navigation

45 Where Possible, You Should Sense Your Outside Environment For Navigation Dead Reckoning Maneuvering without using sensors to determine where you are relative to the positions of the mission models Fix Using sensors to determine your position relative to the mat and mission models by sensing the outside environment Good - Motion with Move/Motor Blocks using time (seconds) Sensitive to starting position Sensitive to starting orientation Sensitive to battery voltage Better - Motion with Move/Motor Blocks using internal sensors (rotation or degrees) Sensitive to starting position Sensitive to starting orientation 52 Best - Motion with Move/Motor Blocks while sensing or contacting the external environment (light, color, touch, ultrasonic, wall, mission model, strategic object) Relatively insensitive to starting position and orientation Sensitive to sensor performance and environment

46 How Accurately You Need To Navigate Depends On What Part Of The Mission You Are Executing Initial Guidance When leaving the base, sometimes you can be pretty loose with your navigation accuracy Midterm Guidance While approaching the mission models, you should tighten up your navigation accuracy Terminal Guidance At the very end of your maneuvering, you must ensure the accuracy and precision of your navigation are sufficient to get the job done Some of the better teams can program some of their missions such that they can loosely place the robot in the base and have the robot figure out where it is and where it needs to be after leaving base 53

47 If Your Robot Needs Accurate Alignment In The Base, Consider An Alignment Fixture Picture courtesy of Marco Ciavolino The attachment needs to be made out of LEGO-manufactured pieces [Rule 4] The team member must not be touching the alignment fixture when the robot leaves base [Rule 16] 54

48 Back To Agenda

49 Motor Reset Blocks

50 Basic Robot Maneuverability Motor Reset Blocks

51 Move Block Error Correction and Motor Reset Blocks Going 8 Rotations With A Final Brake 8.0 With one move block, the motors will go exactly 8 rotations Notes: The last move block in each sequence above uses brake, all of the others coast.

52 What Are These Motor Reset Blocks Actually Doing? Both move and motor blocks will keep track of, and try to correct for, accumulated errors in the motors These errors are typically very small when the motor and move blocks include a brake When the coast option is used, these errors can build up Setting direction to stop does not appear to reset accumulated move or motor errors This might be an error in the NXT-G help It is never necessary to use motor reset blocks at the beginning of a program All motors are automatically reset at the beginning of a program Motor reset blocks might be helpful at the beginning of code packaged in myblocks It depends on what the motors are doing prior to and at the beginning of the myblock 59

53 The Bottom Line: Expert s Recommendation On Motor Reset Blocks For most FLL teams, motor reset blocks are not relevant and you never really need them If you use brake for all of your movements, as many FLL teams do, accumulated errors are small It s coasting that causes big errors to accumulate The main good use of motor reset blocks in FLL is when teams combine more than one outing into a single longer program (e.g. a menu or sequencer program) In this case, it is necessary to coast the motor(s) to make it possible to adjust a motorized attachment between outings, since the program is still running Coasting the motors may cause large errors to accumulate (as the humans move the coasted motors between outings) which will forwarded to the next motion, which is definitely not the desired result. In a sequencer, each outing should begin with a Red Reset and end with a Coast for any relevant motors Another possible application for the making sure a new motion starts from a fresh measurement would be the first movement after pushing into a stationary object with the intent to stall into it, such as having the robot push into a wall until it stalls At this point, the rotation counts can be unpredictable (especially left to right), and you want your first movement away from the wall to start at zero accumulated error on both sides This is only really applicable if you drive into the wall by rotations/degrees (when seconds is really the better choice when a stall is expected) Many teams are likely to use degrees anyway because they don t know any better 60

54 Back To Agenda

55 Multiple Sequence Beams

56 You Can Use Multiple Sequence Beams For Concurrent Robot Operations While Moving Forward (move block on other sequence beam), move Motor A Move Forward 63 Note: Can do the same thing with a motor block in series with a Move Block as long as you uncheck the Wait for Completion option

57 Branch Sequence Beams Can Be Added In The Middle Of The Main Sequence Beam 64

58 NXT Program Flow Rules The program runs until it reaches the end of all sequence beams or a stop block whichever comes first A Block can only start when there are values on all of the input data wires A Loop Block or Switch Block cannot start until there are values on all of the data wires that enter the block A data wire that starts inside a Loop Block will have a value only when the Loop Block finishes A data wire that starts inside a Switch Block will have a value only when the Switch Block finishes 65

59 Be Careful Of Multiple Sequence Beams Know The Issues With Them! Use multiple sequence beams only when you think you really need them Avoid busy loops where one sequence beam is hogging the CPU Don t try to control the same motor on different sequence beams at the same time Be very careful about data wires going into and out of Loop Blocks and Switch blocks Only one copy of a particular My Block can run at a time If the same MyBlock is on different sequence beams, it will run the first My Block, then run the second instance once the first one completes Copy and rename the My Block if you need to run multiple copies concurrently 66

60 Back To Agenda

61 Data Wires (including Constants and Variables

62 Data Wires Carry Information Between Programming Blocks You create a data wire by drawing it out of a block s data hub Nearly all of the programming blocks have data hubs and can support data wires. Open a block s data hub by clicking the tab at the lower left edge of the block after it has been placed on the work area. The cursor will change shape when it hovers over or is near a data plug. If you then press the mouse button and drag to the right, a data wire will unroll that can be connected to a plug on another block s data hub. To delete a data wire that stretches from left to right between two data plugs, click on the right plug 69

63 Data Wires Carry Information Between Programming Blocks Data wires carrying information to a block (i.e., carrying input) are connected to the plugs on the left side of its data hub. Data wires carrying information away from a block to another block (i.e., carrying output) are connected to the plugs on the right side. 70

64 Data Wires Carry Information Between Programming Blocks You create a data wire by drawing it out of a block s data hub Nearly all of the programming blocks have data hubs and can support data wires Open a block s data hub by clicking the tab at the lower left edge of the block after it has been placed on the work area The cursor will change shape when it hovers over or is near a data plug If you then press the mouse button and drag to the right, a data wire will unroll that can be connected to a plug on another block s data hub. Deleting a data wire To delete a data wire that stretches from left to right between two data plugs, click on the right plug 71

65 Data Wires Carry Specific Types Of Data Each data wire carries a specific type of data between blocks. For example, if a data wire is dragged from a logic plug on a block s data hub, it can only be connected to a logic plug on another block s data hub. Data wires are identified with specific colors: wires carrying number data are colored yellow wires carrying logic (true/false) data are colored green wires carrying text data are colored orange. 72

66 Back To Agenda

67 Line Following Follow The Yellow Brick Road Black Curvy Line

68 2 State Line Follower Most Basic Note: For FLL, these display blocks might be an unnecessary waste of the NXT memory You will not be able to read the display as it is running anyway! Question: How long will this line follower program follow the line? 76

69 3 State Line Follower Adds Go Straight Art of LEGO MINDSTORMS NXT-G Programming Go straight if you are just over the edge of the line 77

70 5 State Line Follower 78

71 Proportional Line Follower This is getting a bit advanced for most FLL teams My opinion: If the children don t understand it, don t use it 79

72 This Line Follower Sets The B Motor Speed To A Constant and Throttles the C Motor Speed 80

73 Proportional Integral Differential (PID) Controllers Are Overkill For Most FLL Applications (But They Show Up At The World Festival All The Time) If your team members cannot understand it, DON T use it. 81

74 There Are Even Fuzzy Logic Line Followers 82

75 Back To Agenda

76 Squaring Up

77 You Can Set The Orientation (Heading) Of The Robot By Backing Into The Wall Or Using Sensors You can use either time or multiple touch sensors to back into the wall and orient the robot perpendicular to the wall at any time You can detect the motor stall condition to see if you are against a hard object (e.g. the wall) You can use light or color sensors to detect the location of a line and orient the robot perpendicular to the line 85

78 Back To Agenda

79 Commenting and Printing Your Programs What the Heck Is This Program Telling Me?

80 Annotations (Comments) In The Programs Help To Document The Program (Judges like it too!) Tip You can enter comments which are generic to the entire program by clicking on the start icon

81 Printing Your Programs

82 You Can Print Directly To Your Printer Or Capture The Printout Electronically In HTML and RTF HTML will create both the HTML code as well as pictures of the code These pictures can be inserted into most document editing programs Rich Text Format (RTF) can be opened with most common word processing programs 90

83 When You Print To A Rich Text Format (RTF), This Is What You Get When You Open It In MS Word

84 Printing To HTML Will Generate Images Which Can Be Cut and Pasted Into MS PowerPoint

85 Back To Agenda

86 Base Operations Time in Base is Time Not Earning Points

87 Back To Agenda

88 Master Programs or Sequencers

89 A Sequencer Program Can Help With Speeding Up Your Pitstops In Base 00-MasterProgram.rbt Author: RobotBillMD Revision: 02 Required Sensors: None (NXT Buttons Used) Consider an initial motor reset and a final coast for your last motor/move blocks when using sequencers This program is used to execute a set of three programs in rapid sequence. Prior to each program, this master program waits for the orange button to be pressed. Credits: This program is adapted from the program provided by Cougar Robotics n=com_content&view=category&layout=blog &id=78&itemid=118 There are many different ways to implement a sequencing program Have your team generate their own! 97

90 Back To Agenda

91 Other References (Books, Websites, etc.)

92 The FIRST Forum Is A Good Way To Discuss And Get UNOFFICIAL Advice On FIRST LEGO League 10

93 The MD FIRST Website Has Many Great Resources 10

94 Make Sure You Sign Up For The FLL Coaches List Service (listserv) 10

95 Our Own Techbrick Provides Resources That Are Used Worldwide Thanks Marco! 10

96 Training Is Available Via Carnegie Mellon 10 LEGO, FIRST and FLL Do Not Endorse Any Specific Tutorial Software

97 In Addition To All Of The Other Lists Of Resources, Consider Some Of These Dave Parker s Website A Frequent World Festival Judge - Well documented NXT-G code! NXT-G Tips & Tricks on Team Hassenplug Website and Code Examples Minnesota FLL High Tech Kids Northern California FLL - Playing at Learning FLL Freak Skye Sweeny 10 Cougar Robotics (former high performing FLL team)

98 In Addition To All Of The Other Lists Of Resources, Consider Some Of These (Continued) Oregon State Robotics The NXT Step 10

99 Telephone Support Is Available For Technical Stuff They Don t Answer FLL-Specific Questions LEGO Education :30AM to 5:30PM CST LEGO Retail :30AM to 5:30PM CST 10

100 Popular Reference Books

101 Jim Kelly s Book On FIRST LEGO League Has Been Pretty Popular This book is a bit dated, so remember that the official rules take precedence 10

102 Programming References In Print 11

103 Additional Print References 111

104 The LET S GO Boys and Girls Manual Provides A Curriculum and Instructional Exercises For FLL 11

105 The Help Provided With The NXT-G Software Is Well Documented and Very Helpful 11

106 Programming References In Print 11

107 A Very Good (and Free) NXT-G and EV3 Tutorial Is Available at STEMcentric.com NXT Tutorial: EV3 Tutorial 11 LEGO, FIRST and FLL Do Not Endorse Any Specific Tutorial Software

108 Training Is Available Via Carnegie Mellon 11 LEGO, FIRST and FLL Do Not Endorse Any Specific Tutorial Software

109 Back To Agenda

110 Generic Tips and Recommendations

111 The NXT-G Software Has Default Ports For Various Outputs and Sensors While you can reprogram each port for a different device, it is easier to stay with the default outputs and sensors for each port Port Default Usage Notes A Motor Block and Lamp* Block Attachment motors, if needed B Move Block Robot mobility ( left motor) C Move Block Robot mobility ( right motor) 1 Touch Sensor 2 Sound Sensor (Not Allowed In FLL) 3 Light Sensor 3 Color Sensor 4 Ultrasonic Sensor 11

112 If You Have A Block That You Would Like To Reuse, Use <Control> Mouse Drag To Replicate For FLL, you should use port 2 for the second sensor, if you use more than one of a certain type Tip B/C A

113 When Debugging Software, Here Are Some Tips Annotate your software so you know where to make any changes If you think you have several changes Change only one thing at a time Start with the changes closest to the beginning of the program You can put sound blocks in to have the robot give you audible signals when the robot does something Drawback: the soundblocks will take up extra memory in the NXT You can put breaks in the code by inserting a motor stop block followed by a wait for block (one possible example provided below) 12 This could be made into a myblock

114 Highly Recommended! File Naming Convention and Regular Backups Tell the team to use a standard naming convention One I like is <Person s Initials><Short Description><Version Number> For example: wbapickupmeat_v2 Create an online backup of the programs every day Create an online back up of the profile directory by just copying this folder pasting it to the same folder: C:\Documents and Settings\<Username>\My Documents\LEGO Creations\MINDSTORMS Projects\Profiles\Default I usually do not use different profile names with NXT-G; I use the default profile for the entire team This ensures any myblocks etc. are all shared by the team See naming convention above to prevent overwriting myblocks Periodically, create an offline backup by copying this folder to a USB thumbdrive or equivalent 12

115 Bluetooth Is Disallowed By FLL At The Competition Bluetooth Can Be Used During Your Practice Tip Bluetooth communications are not allowed at the competitions Bluetooth can be very helpful during practices The NXT Brick has Bluetooth built-in You either need a computer with built-in Bluetooth or you need a Bluetooth dongle

116 How To Connect Via Bluetooth to NXT Robots Thanks to Andy Traiger of Vienna Robotics Turn on the computer Slide in the Bluetooth dongle (some computers do not boot with the dongle installed) On the computer, open the Bluetooth Devices window If any NXT device is listed in the Devices list, Remove it (otherwise, a 'Line Busy' error will pop up later). Make sure 'Turn discovery on' is selected. Close the Bluetooth Devices window. Switch on the NXT, and select 'Search' from the Bluetooth menu, then 'Connect' to the found computer. Accept the passcode [1234]. On the PC, a window comes up mentioning that a Bluetooth device is requesting to connect, asking if you want to allow connection. Click on the message to allow connection. A new window pops up, asking for the passcode. Type in the passcode and click Next. Again, the NXT beeps to verify the passcode; press the orange button on NXT to accept. Open the Bluetooth Devices window. Select the NXT device and press 'Properties'. In the new window that opens, click the 'Services' tab. Now, Windows starts searching for services that NXT supports. Select all available services (in my case, two serial ports) and press OK. Windows now installs some new drivers. After that, close the Bluetooth Devices window. Now, start the Mindstorms software on the PC, and open the NXT window. Scan for NXT devices, and after finding NXT, click "Connect" (if not already connected during scanning). 12

117 Back To Agenda

118 Here Is A Way To Detect How Many Touch Sensors Are Pressed Connect all of the touch sensors together using RCX to NXT conversion wires and plug them into one port 126 Please give RobotBill credit for this within the comments of your program if you use this technique