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The force profile/mechanical advantage of the end effector should ideally peak at the maximum close position (small relative distance between critical points) to maintain adequate contact with the object being picked up. The plot below demonstrates a possible ideal plot of mechanical advantage, calculated from the design of end effector iteration two. For future iterations, a better alternative would be to design a system that achieves a mechanical advantage that approaches infinity as the linear displacement decreases.
Kinematic Analysis
We chose to focus on the kinematic/position analysis for the overall linkage system because its motion determines the opening/closing/position of the end effector and the rotation/displacement of the package volume.
Through prototyping, it was found that the ideal motion path was not possible using a sharp-cornered curved slot. Thus, kinematic analysis was performed on a similar system using a constant radius slotted input link to simulate the effect of the linear component of the ideal path. The position analysis and generated positional graphs of the output point below are obtained through MotionGen.
Position Analysis of Output Point
Associated Displacement, Velocity, and Acceleration Graphs:
The results of the kinematic analysis demonstrate that using a constant radius input link without a linear component to the path results in poor synchronization between the end effector and the rotating linkage system. It can be easily seen from the animation that the relative distance between the critical points changes throughout the entire rotation path, indicating that the end effector will open and close while the linkage system is not in its optimal 90 degree and 0 degree position (pick up and drop off position). Moving forward, we would like to explore the effects of a multi-radius slot path that is both manufacturable and isolates change in distance between critical points to optimal points in the rotation.
Mechanical Advantage Analysis
The analysis below will focus on the end effector. We chose to focus on the mechanical advantage of the end effector because the main goal of the end effector is to maintain adequate package contact through force applied from the end effector links.
First Iteration Mechanical Advantage Second Iteration Mechanical Advantage