4 Bar Linkage: Thinking in the Box Siri Maley FIRST Team 1640, 28 January 2011

Design Constraints The 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 Goal We 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 Issue There are a lot of dimensions to play with…

Solution – Inventor Model 4-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”

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