Project Proposal - Team 14

Intro: Davis’s cat, Kermit, is mostly nocturnal and gets very active at night. We wanted to design a machine that can keep him entertained and assure he is getting good exercise. His favorite toy is a wand mouse that must be manually flung around in order to simulate mouse movement. In order to combat this, we aim to create an extended crank-rocker system that can shake the toy back and forth automatically. We also want to keep cats interested, so we want our mechanism to follow a unique and entertaining output path.

Problem Statement: The two main challenges of this project both involve the output path. The first is that we do not just want the wand to shake back and forth as cats would very quickly get bored with it. In order to get a unique output path, we plan on adding a cam to the linkage system, allowing the output link the ability to move in unpredictable ways. The second challenge is that wand must able to jump in the z-direction. Cats love to jump to try to catch objects so this ability becomes a necessity.

Proposed Mechanism: Our proposal to solve these unique challenges is to essentially build two four bar linkages: a crank-rocker on the top side and E-quartet mechanism on the bottom. The crank-rocker will shake the wand toy back and forth along the XY plane. On the bottom side, the E-quartet will use an expanded ternary link to spin a specially designed cam in a circle. This cam will create our desired path. Giving the wand the ability to jump the Z direction will be solved by adding a hinge to the grounded links of the rocker. This will allow free movement in the Z direction.

This the target path:

Proposed Scope of Work: Our scope of work will go as follows:

• CAD together a working four-bar crank-rocker system
• CAD together E-Quartet system that spins circular plate
• Create cam design that outputs desired output path
• Evaluate and adjust system as needed
• Test on Kermit!

Preliminary Design(s):

Cam Design:

Grashoff Condition (For Rocker):

S = 100 mm

L = 200 mm

P = 125 mm

Q = 185 mm

S+L <= P+Q

300 <  310 (Satisfies Grahsoff Condition)

Gruebler's Equation:

3(L-1) - 2J1 - J2

3(6-1) - 2(6) - 2 = 1 degree of freedom