2. Four bar mechanisms for analysis

The link I have labeled as link 4 in the following pictures is key to analyzing the position of the visible parts of this model because it is attached to all of them. The first two pictures show a side view of the model and the third one shows a front view. The joints on link 4 that are not relevant to the analysis of each individual four bar have been omitted for convenience of viewing.

Internal Four bar (side view)

This four bar mechanism includes the input crank (2), body (1), and two links (3 and 4) that are not visible from the outside of the mechanism. Since the angle of link 4 remained constant, this four bar was slightly different from four bars we have worked with so far in the class. However I was able to use the same vector loop method that worked on previous four bars.

Mouth (side view)

This four bar includes the same link 4 from the first four bar, the body, and two new links (5 and 6). Links 4 and 6 make up the mouth of the bear which appears to open and close while rotating the input crank. This four bar was relatively simple to analyze since the positions of link 4 are known from the first 4 bar.

Arms (front view)

The Last 4 bar is actually more of of a 3 bar mechanism since the links on the left and right are symmetrical and only one of them needs to be analyzed to get the results for both. Again, the results from the first four bar can be used since the only new link is link 7 (the arm). This mechanism is a little strange- link 7 is free to rotate but it is pinned to a specific location on link 4 and must pass through a thin slot on the side of the body. This slot and the position of link 4 determine the angle of the arm.