II. Design Process

To begin the design process, we began by trying to understand the desired motion pattern. The sketch below shows the force and velocity over the duration of the gripper’s movement.

While grabbing the bottle, the force should be high while the velocity can be slow. Once the gripper starts the swing, the force should be maintained throughout the movement to ensure that the bottle does not slip out. The velocity at this point would be 0, as the gripper is clamped on the bottle and is not moving. In the releasing motion, the velocity should be high for the bottle to be flung. The force at this time has no requirement, but it will likely be low as a trade off for speed.

We weren’t able to determine specific target values for each point of the motion. However, we decided that a quick release mechanism would suit our needs given that the force needed to be high in one action, and velocity in another. We then used PMKS to iteratively test different link lengths with the goal of focusing on the fast velocity upon release as this seemed to be the most vital aspect of the project.

From our iterative design process, we found a link length ratio that was the quickest out of all the ratios we tested. The image below shows this ratio.

We then sketched out what we expected our final prototype to look like. We wanted to create two quick release mechanisms, with one side driving both mechanisms. They would be connected in the middle, which would be where the bottle would be gripped.