FLL Robot Design Workshop

Transcription

1 FLL Robot Design Workshop Tool Design and Mechanism Prepared by Dr. C. H. (Tony) Lin Principal Engineer Tire and Vehicle Mechanics Goodyear Tire & Rubber Company

2 Description Mechanism (Attachment) is extending a simple robot into a powerful robot that can control and change its environment. Learning about how properly design attachments for your robot to meet a particular challenge can make for a winning robot.

3 A Systematic Design Methodology 1. Identify the functional requirements, based on mission requirements, of a class of mechanisms of interest. 2. Determine the nature of motion (i.e., planar, spherical, or spatial mechanism), degrees of freedom (DOF), type, and complexity of the mechanisms. 3. Identify the structural characteristics associated with some of the functional requirements. 4. Enumerate all possible kinematic structures that satisfy the structural characteristics using graph theory and combinatorial analysis. 5. Sketch the corresponding mechanisms and evaluate each of them qualitatively in terms of its capability in satisfying the remaining functional requirements. This results in a set of feasible mechanisms. 6. Select a most promising mechanism for dimensional synthesis, design optimization, computer simulation, prototype demonstration, and documentation 7. Enter the Building phase.

4 Robot Design and Construction Planning what does the team want to achieve and how will they achieve it? Let the kids do it! Design iteration Brainstorm (what to build) Design (how to build it) Build it! Test it! Repeat until it s perfect (or good enough) Trade-offs: Good, Quick, Cheap pick two (at most)! Quality Schedule Budget

5 How to make things stiff Use your hypotenuse! Use right triangles 3-4-5, , , (5,12,13) etc. Interlock bricks & beams Two thin bricks in between Lock with vertical beam Triple beams (double shear) Three-pins instead of two pins Technic Design School Courtesy of Team RED Robot Construction and Design

6 Demonstration Three-pins vs. two-pins when used with more than three beams Two pin structures bend Three-pins much more rigid Stacked beams with grey two-pins Stacked beams with black two-pins Stacked beams with black/blue three-pins Courtesy of Team RED Robot Construction and Design

7 How to make things strong Use large parts Don t use several small parts when one large part will suffice Stiffness decreases with the number of parts used to do a task Use L-beams to form right angles Do not use two beams and a pin, use an L Make structures out of beams, not axles when possible Axles are more flexible than beams consistency and precision Courtesy of Team RED Robot Construction and Design

8 Stiffness v. Length Demo If we need something longer than 15 Two beams overlapped More overlap = stronger beam 2 x 11 2 x 15 Courtesy of Team RED Robot Construction and Design

9 Classification of Mechanisms No DOF Mechanisms Planar Mechanisms (1-2 DOF) Planar Linkages Geared Mechanisms Chain & Pulley Spatial Mechanisms (1-3 DOF) Spherical Mechanisms (>= 3 DOF) * Remember your robot can move

10 Examples

11 Examples

12 FLL Robot Attachments (Standard Kits) Passive Attachments Pushing attachment Hooking attachment Dumping attachment Collecting attachment Spring-loaded attachment Power Attachments Grabbing attachment Lifting attachment Pushing attachment Turning attachment Hooking attachment Dumping attachment Collecting attachment

13 Passive Attachments Pushing attachment Flat surface or Angled surfaces Move game elements independently or in a container (Flat surface ) Move game elements out of robot s path (Angled surfaces)

14 Example: 2010 M&M s design

15 Complete Examples

16 Exercise #1 Build Push Plate (15 minutes) Pins Guide Attachment BOM Instruction

17 Passive Attachments Hooking attachment Fork and Hook attachments Collecting special objects Can be combined with power assist to lift, sweep and drop

18 Example: 2010 M&M s design

19 Complete Examples

20 Exercise #2 Hooks(15 minutes) BOM Instruction

21 Passive Attachments Dumping attachment Container to move game elements to specific location Based on basic four-bar linkage or simple hinge mechanism

22 Example: 2011 Brazing Brains design

23 Exercise #3 Four-Bar Carrier(30 minutes) BOM Instruction

24 Passive Attachments Collecting attachment Object trap - Box opens only inward Sweeper moving object in certain direction Capture objects to return to base

25 Example: 2011 Brazing Brains design

26 Exercise #4 Trap Box (30 minutes) BOM Instruction

27 Passive Attachments Spring-loaded attachment Snap or pre-loaded Collecting, hitting, or turn Combining with other mechanisms or trigger

28 Example: 2011 Brazing Brains design

29 Exercise #5 Spring Loaded Hook (20 minutes) BOM Instruction

30 Exercise #6 Spring Loaded Trigger (20 minutes) BOM Instruction Courtesy of Team RED Robot Construction and Design

31 FLL Robot Attachments Passive Attachments Pushing attachment Hooking attachment Dumping attachment Collecting attachment Spring-loaded attachment Power Attachments Grabbing attachment Lifting attachment Pushing attachment Turning attachment Hooking attachment Dumping attachment Collecting attachment

32 Power Attachments Using third motor as power source to generate controllable motion Attachments would be designed to connect to the fixed motor Considerations: Motor location Moving space Moving speed & torque

33 Power Attachments Grabbing and Collecting attachment Claw, Vise Grip, Trap

34 Power Attachments Lifting, Hooking and Dumping attachment Lever, Forklift, Trap

35 Example: 2010 M&M s design

36 Exercise #7 Forklift(40 minutes) BOM Instruction

37 Power Attachments Pushing attachment LEGO Actuator or Custom Actuator

38 Power Attachments Turning attachment Controllable turning action Define turning angle, direction and arm length Gear type, ratio and direction

39 Gears and Usage Regular spur gears Gearing up or down, changing speed or torque, Converting rotary to linear motion (rack and pinion) Bevel gears and crown gears Change shaft direction by 90 degrees Note direction of rotation changes (4 tooth is also good for this task) Torque Will only apply a given level of torque before slipping Worm Changing direction, speed, and torque (it s a 1 tooth gear) Eliminates back driving Gear Ratio = No. Teeth Input /No. Teeth Output

40 Example: 2011 Brazing Brains design

41 Exercise #8 Gear & Grip (40 minutes) BOM Instruction

42 Example Videos 3PS7nIihOw Passive and power attachments 7RiDjcm5Dg Power attachment forklift & actuator T5_ziLhENE&feature=related Passive and power attachments * Identify mechanisms that had been used within each video.

43 FLL Robot Attachments (Non-Standard Kits) Pneumatics operation Pneumatics give the robot another power source of manipulation besides LEGO NXT servos (motor) Powerful Partial controllable motion - On/off switch with pneumatic actuator

44 Examples lifting attachment

45 References Mechanism Design : Enumeration of Kinematic Structures According to Function, Lung-Wen Tsai Winning Design! LEGO Mindstorms NXT, David J. Trobaugh Designing for FLL with Lego Mindstorms Hints and Tips, Team Unlimited, FTC0001, unlimited.syraweb.org Robot Mechanisms and Mechanical Devices Illustrated, Paul E. Sandin Building Robots with LEGO MINDSTORMS, Mario Ferrari, Giulio Ferrari, and Ralph Hempel