140 likes | 264 Views
Robot Construction Basics. Les Turner Director of Technology, Northern Indiana ESC Head Coach, Bremen Botz ! coach@bremenrobotics.org www.bremenrobotics.org. Bremen Botz! Team Members. Preston Huffman Lead Builder – Robot Base Zac Ericson Lead Builder – Attachments Josh Turner
E N D
Robot Construction Basics Les Turner Director of Technology, Northern Indiana ESC Head Coach, Bremen Botz! coach@bremenrobotics.org www.bremenrobotics.org
Bremen Botz! Team Members • Preston Huffman • Lead Builder – Robot Base • Zac Ericson • Lead Builder – Attachments • Josh Turner • Lead Programmer • CordallSchoning • CAD Design / Programmer Robot Construction Basics Les Turner, Northern Indiana ESC
MINDSTORMS NXT SYSTEM Lego NXT consists of: Lego NXT Controller Servo Motors Sensors (Light, Color, Sound, Touch, Ultrasonic) Software to program the NXT Controller Lego gears, beams, pins, wheels, & other parts. Robot Construction Basics Les Turner, Northern Indiana ESC
Get To Know The Parts • Not all Lego parts are the same: • Connecting Pins • Black Connecting Pins (Friction – Hold Tight) • Gray Connecting Pins (Free – Will Rotate) • Blue Axle Pins (Friction – Hold Tight) • Grey and Yellow Axle Pins (Free – Will Rotate) • Friction Gear (Allow axle to rotate when bound) • Other Specialized Parts are available! Robot Construction Basics Les Turner, Northern Indiana ESC
Objectives for Construction Usually revolves around an FLL tournament: Robot to accumulate as many points as possible in 2 min 30 seconds. No human interaction with the robot outside of the defined base. Highest Score wins, ties are broken with 2nd highest scores (or sometimes time) Robot Construction Basics Les Turner, Northern Indiana ESC
Robot Construction Three R’s Robustness:The robot needs to be quick enough to accomplish all tasks within time. Rigidness:The robot needs to be constructed solidly to eliminate play and slop. Repeatability: The robot needs to use landmarks and other techniques for accuracy. Robot Construction Basics Les Turner, Northern Indiana ESC
R1 - Robustness • Understanding Motion and Measurement • Wheel Size Has An Impact • Larger is Faster, but less Accurate • Smaller is More Accurate, but is Slower • Gearing may help, but changes Torque (Power) • Wheelbase Issues (Distance Between Wheels) • Greater the Distance, Greater the Accuracy • Allows more degrees of rotation for same movement • Any sideways movement of wheel introduces error Robot Construction Basics Les Turner, Northern Indiana ESC
R1 - Robustness • Gearing (Standard Gears) • Large Gear Driving a Small Gear • Can Achieve High Speeds at the Expense of Power • Small Gear Driving a Large Gear • Higher Torque at the Expense of Speed • Worm Gears • Very Slow with Extreme Torque • Flat Gears • Extended Range of Motion (Speed Set by Drive Gear) Robot Construction Basics Les Turner, Northern Indiana ESC
R2 - Rigidness • Solid Construction • Multiple points of connection (drive wheels) • Use Axle Clamps to hold items tight on axles • Can’t use too many pins, only wrong ones • Keep all gear meshing tight to minimize slop • Brace robot structure so parts do not detach easily • Route cabling so it doesn’t interfere with robot • Don’t forget access to charging and USB ports! Robot Construction Basics Les Turner, Northern Indiana ESC
R3 – Repeatability (Robot-Based) • Minimize Friction • Wall Following Wheels • Third Point of Contact (Fixed or Pivot Wheel) • Use Physical Limits on Robot for Arms • Always ‘Home’ the Arm Against Limit • Use Limit to establish operating position • Use Sensors to Establish Limits / Position • Touch / Ultrasonic Sensors to Detect Limits Robot Construction Basics Les Turner, Northern Indiana ESC
R3 – Repeatability (Table-Based) • Establish Points of Reference on Table • Don’t Overlook Anything on Table (Tissue Box?) • Walls make great alignment tools and limits • Lines or other markings on table for reference • Even Table Elements may be used for alignment! • The Light Sensor is Your Friend! • FIRST almost always put lines where needed! • Use the black lines around base as initial reference • Build a shield for the Light Sensor (Ambient Light) Robot Construction Basics Les Turner, Northern Indiana ESC
Lets Build a Robot! • Front Sheet 10 – Sturdy Motor Attachment • Left Motor Wire to Output B on NXT • Right Motor Wire to Output C on NXT • Back Sheet 20 – Long Front Setup • Modify to attach to existing beams from step 1 • Add a wheel to bottom of front arm. Think about ways to ‘solidify’ this robot! Robot Construction Basics Les Turner, Northern Indiana ESC
Programming • The robot doesn’t do much without a program • We will write a basic move and turn program • The NXT-G Programming Environment is very easy to use and is very powerful. • Programming details are for another session! Robot Construction Basics Les Turner, Northern Indiana ESC
QUESTIONS & ANSWERS Contact Info: Les Turner coach@bremenrobotics.org www.bremenrobotics.org Robot Construction Basics Les Turner, Northern Indiana ESC