1. Motors, Materials, and Fasteners Essential things to know for choosing motors, and assembly of the robot. Robotics 101

2. Motor Elements An electric motor is all about magnets and magnetism. A motor uses magnets to create motion. If you have ever played with magnets you know the law of magnets: Opposites poles attract and like poles repel. So if you have two bar magnets with their ends marked "north" and "south," then the north end of one magnet will attract the south end of the other. On the other hand, the north end of one magnet will repel the north end of the other. Inside an electric motor, these attracting and repelling forces create rotational motion. The armature (or rotor) is an electromagnet. Like the Beakman rotor above made of copper wound in a circle, the motor below has copper wound around a soft iron core. The field magnet is still a permanent magnet, only this time there are two semi-circular magnets fitted inside a steel casing. In some larger motors and generators the field magnet could also be an electromagnet. In smaller motors it usually isn't to save the electricity that would otherwise be needed to make magnetism and also to reduce complexity. Actually, these days there are quite a few large motors using magnets to drive cars. If you take apart a small electric motor, you will find that it contains the same pieces described above: two small permanent magnets inside casing, two brushes held in a housing, and an electromagnet made by winding wire around pieces of shaped metal (laminations) on a steel shaft, known as an armature or rotor. Almost always the rotor will have three poles or more.

3. Motor Specifications Torque Versus Speed Motor Curve Torque Speed Almost any motor can be characterized by this curve. They may not exactly fit, but they are close. “0” Speed Min “0” Torque

4. Motor Specifications Torque Versus Speed Motor Curve Torque Speed “0” Speed Min “0” Torque 0 Speed Max Torque, Max Amperage (“Motor Stall”) Maximum Speed 0 Torque, Min Amperage (“Free Load”)

5. Motor Questions When do you get the Motor Stall operation? When do you get the Motor Free Load operation? Will you normally see a motor operation this way?

6. Motor Questions When do you get the Motor Stall operation? −Physically holding the motor output shaft. −Something is in the way of the motor appendage (a physical stop). −Motor does not provide enough Torque (Force) to Move the appendage or load. −The internal motor is damaged or jammed. When do you get the Motor Free Load operation? −No Load, Power Motor in Free Air −Set Screws Loosen (Do Not Ever Use Set Screws On a Warlock Robots!) −Pin Sheared (Pins usually do not work due to extreme loads and directional changes- happens often!) −Gear Sheared (Happened 3X, it’s a rare event caused by comprising weight and maximizing load) −Keyway Sheared (Believe it or not I have seen this- extremely rare) Will you normally see a motor operation this way? −THIS IS WHERE YOU WANT TO BE!- Not Stalled and Not Freely Spinning −Sometimes- but usually want to avoid it!

7. Torque vs. Speed Torque Versus Speed Motor Curve Torque Speed “0” Speed Min “0” Torque 0 Speed Max Torque Max Amperage (“Motor Stall”) Maximum Speed 0 Torque, Min Amperage (“Free Load”) THIS IS WHERE YOU WANT TO BE! Notice Your Guarantee: You will never run at full speed AND You will never run at full torque Remember C.R.B.!

8. Torque and Power vs. Speed Below is the power curve for a DC motor. The yellow parabolic curve is a plot of Power vs. Speed, and the white linear curve is a plot of Power vs. Torque. Power is the product of torque and rotational speed. As you can see from the plot, power is a maximum at the point on the torque/speed curve where torque and speed are equal to one about half of their maximum values.

9. CIM Motor Specs (Drivetrain Motor) 337 W =0.4517 Horsepower Maximum R. Operating Point When Pushing At Max Power (Ramming Speed) C. Operating Point At Max Speed- (Cruising Speed) B. Operating Point When Banging Your Robot Against at Wall or Another Robot (Butting Speed)

10. CIM Motor Design (Drivetrain Motor) CIM MotorGearboxWheel Max Torque @ 2655 RPM 0.8958 ft.-lbs.16/114.33 ft.-lbs. Max Speed @ 0 Torque 5310 RPM1/16331.8 RPM Torque/Speed Gear Down Introduction CIM Motor Drives Gearbox 16:1 Wheel +12V Power Supply Max Power: 172 oz.-in. = 0.8958 ft.-lbs. @ 2655 RPM

11. Delphi “Van Door” Motor 35Nm =25.8 ft.-lbs. 75 RPM Uses: 1)Arm 2)Lifting/Pushing 3)Some Back drive though

12. Gear Motor Uses: 1.Winch/Arm 2.Various gear ratios 3.Some Backdrive 19Nm =14 ft.-lbs. 100 RPM

13. Window Motor 12Nm =8.85 ft.-lbs. 70 RPM Uses: 1)Positioning 2)Holding in Position 3)Actuation of Mechanism 4)Almost no Back drive!

14. Materials Super Safety Geek! Man of Steel Cloak of Bronze Imprinted with Brass Transparent Polycarbonate For Protection Aluminum Diamond Plate For Solid Appearance Nylon Noose to Drag Him Offstage Plastic Safety Glasses Titanium Shoes (for Weight & Strength) with rubber soles so as not to damage carpet. Carbon Fiber Framework for lightness Smok’n

15. Polycarbonate Polycarbonate is Bullet Proof Glass (What an Invention) Oh No Not again! He isn’t worried. He has Bullet Proof Glass protecting him!

16. Materials Now Seriously, lets talk about Materials.

17. Metal Density Higher Density/Higher Weight

18. 80/20: Industrial Erector Set 80/20 Extruded Aluminum

19. Polyvinylchloride (PVC) PVC Possibilities Don’t Forget: −Polyurethane −Polyethylene −Vitron −Or Silicon Rubber Plastic plumbing on a robot? Why not!

20. Fasteners Screws, Bolts and Nuts −Metal, Wood, Set −Hex, Phillips, Slotted, Star, Allen, Square −Pan head, Flat Head −Nuts, Washers, Lock washers Nails (prototype only) Tape −Electrical, Duct, Scotch, Double Backed Welds −Steel −Aluminum Rivets Chain −Master Link −Half Link Collars and Ties −Zip ties −Split collar for shaft Adhesives −Epoxy −Loctite

21. Screws Flat head Screw Driver for Slotted Screws Phillips Head Socket Head (Allen Wrenches)

22. Nuts and Bolts Bolts Nuts Socket Set used To Put On/Off

23. Screw Size Decoding Screw Count −6-32 is 6/64”= 3/32” diameter 32 threads per inch −8-32 is 8/64”= 1/8” diameter 32 threads per inch −10-32 is 10/64”= 5/32” diameter and 32 threads per inch −¼” -20 is ¼” diameter and 20 threads per inch Remember: Lefty Loosey, Righty Tighty

24. Drill & Tap −Why? Create your own screw hole in a slab of metal −Hole is drilled slightly smaller than screw hole (use drill and tap sheet) and a tap cuts the grooves for the screw. Literally, the tap threads the hole. −Oil is used to lubricate while threading −In and Out technique is used to clear metal out of tapped hole Dies are used to put threads on a rod- Tap-

25. Tap & Die Sets Tap Set Tap and Die Set

26. Tape & Glue Tape −Duct tape is not allowed on the robot to connect anything, it is against FIRST rules. −Electrical Tape is only allowed on a robot to insulate wires. −Other tape is allow for decoration of the robot only. Adhesives −Super Glue- Loctite −Epoxy, 2 Parts −Cement −Hot Glue Uses: Tread on Wheels, Small Sensors etc.

27. Welding Aluminum Welded Frames are the typical technology used in constructing a robot for the following reasons: −Removes Screws & Nuts from robot −Removes Brackets from Robot −Improves structural integrity- nothing gets loose −Smaller aluminum tubing can be used while keeping equivalent strength −Reduces weight up to 10 lbs. −Improves look and perceived quality of workmanship.

28. Riveting Rivets −Aircraft have used rivets since the 1920’s and 1930’s to improve aerodynamic performance while keeping the same structural integrity. −Aircraft use aluminum and rivets just like robots. Impacted by Rivet Gun Rivet Gun Cuts and Deforms Pros: Light weight (for robotics we use relatively small rivets) Great for attaching thin materials to each other as long as you can drill a hole. Cons: Removal- must usually drill out the rivet.

29. Collars Split Collars Clamps for Shafts Shaft Wheel Collars Keep Wheel on Shaft

30. Zip Ties

31. Roller Chain Links Chain Connecting Links Half Links Full Links