4 Bar Linkage:Thinking in the Box
Siri Maley
FIRST Team 1640, 28 January 2011
Design ConstraintsThe 4-Bar Linkage has several states it must
geometrically accommodate:
Top Score
Mid Score
Low Score
Floor Pickup
Feeder Pickup
In addition to fitting in the starting envelope & not leaving the 84” cylinder
Design GoalWe know this is possible; our issue it optimizing the
design.
Optimization Parameters Low Weight Low CG (don’t tip) Low Moment of Inertia, I (be nice to the motor) Best “Safe” Configuration (claw/tube near bumper
perimeter) Quick Pickup & Scoring Easy Implementation Robust & Maintainable
Design IssueThere are a lot of dimensions to play with…
Solution – Inventor Model4-bar25.iam
How to Move the Parts: Jaw – Bimba 4 rod 3:1 mate “JawCylinder” open=-3,
closed=0 Tilt – Bimba 4 rod 3:2 mate “TiltCylinder” tilt=-3, flat=0 Linkage – Linkage3-short mates “StartConfig” &
“DeployedConfig”
Boundaries: Starting Box – Clear polycarbonate width & height 84” Cylinder – Smoked polycarbonate width Feeder Height – Smoked polycarbonate height
Starting Configuration
Capture Mode
Note: linkage and plate subsequently shortened
Possess Mode
Eat Mode
Place Mode
Score Top-Inside
Score Top-Outside
Score Mid-Inside
Score Mid-Outside
Score Low-Inside
Score Low-Outside
Release Mode
Closest to 84”
Closest to 84”
Also represents “safest” configuration (most within bumper perimeter)
Current Draft
Next Steps Z-axis gripper mounting
2 arm plates or 1? Assembly
Shafts, bushings, collars, etc? Arm drawings
Test before fiberglass Fiberglass attachments
