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