The arms of the bear can also be modeled as a slotted link rotating about a pin where the physical slot would be. The hands are attached to link d able to rotate quite freely. For the sake of simplicity we will assume that the link d and b, mentioned in the previous section, are always perpendicular to the arm slots.
Figure 8: Arm Mechanism.
We can see different values of the bear arm on the figure. b2 b2 and d1 d1 are the length of each link within the body. h is the distance between the link b2 b2 and the arm, k is the distance between the link and the slot, l is the total size of the arm from the attachment point to the outside (this is just the arm, not the forearm or paw), m is the arm extension outside of the body, and n is the distance between the slot at the base and the arm slots. theta5 θ5 is then defined as:
| Latex formatting |
|---|
\begin{equation}
\theta5theta_5 = \arctan(\frac{n-(b_2+h)}{k})
\end{equation} |
Given the angle of the link l, we can find the extension m:
| Latex formatting |
|---|
\begin{equation} m = l-k\cos\theta_5 \end{equation} |
With these equations, Matlab now outputs the following graphs:
Figures 9 & 10: Length of Section m, Angle θ5.