Switch flipping mechanism

This mechanism is a quick return mechanism which drives a laser cut part to hit the switch. Using Fusion360 we were able to model the mechanism and determine all link lengths in millimeters, labeled in the drawing below.

The hand calculations for mobility, position analysis, and velocity analysis are shown below. The mechanism is a six bar mechanism so the first step for analysis was creating 2 vector loops. One loop includes the two grounded pins and the sliding pin and the other loop includes one grounded pin and the slider.

Once we had our basic equations, we used Matlab to plot the relationship of the sliding pin and the output slider versus the input angle, theta 2. The output slider needs to have a larger velocity and larger change in position to hit the switch. We also plotted the relationship between theta 3 and theta 2 and the angular velocity of link 3 versus theta 2. 

Using modeling in Fusion360, we created an animation of the linkage operation in the full range of motion as shown below. The mechanism is driven by one input shaft which is linked to the motor and rotates 360 degrees.

Raise/lower mechanism

The raise/lower mechanism is a 4 bar mechanism which has 1 degree of freedom, and its link lengths (in mm) are shown below. 

To perform the kinematic analysis, Matlab functions for four bar position and velocity analysis were used. The resulting plots are shown below. The mechanism’s input link (link 2) has a 360 degree range of motion, and its output link (link 4) moves between 20 and 80 degrees. The output link’s motion is what is used to raise/lower the finger wagging assembly. 

An animation of the mechanism, created in Fusion360, moving through its full range of motion is shown below. 

Finger wagging mechanism

The finger wagging mechanism is a 4 bar mechanism which has 1 degree of freedom, and its link lengths (in mm) are shown below. 

The desired output was a rocking motion that imitates the wagging “no” gesture of a finger.

Using GIMP, image analysis from this animation shows that the maximum angle of finger wagging is 41.62°, however the animation also includes hand motion which accounts for roughly 10° of extra motion. This analysis would suggest that the desired range of motion should be 32°, however, I myself was not able to create such a large angle, achieving only 24.33°.

Still, my finger wagging motion was still recognizable, so there is a wide range of angles that can adequately imitate finger wagging.

To perform the kinematic analysis, we used Matlab for four bar angle analysis. The resulting plot is shown below. The mechanism’s input link (link 2) has a 360 degree range of motion, and its output link (link 4) moves between 20 and 80 degrees. The output link’s motion creates the finger wagging motion. The maximum angle achieved is 57.1°, and the minimum angle achieved is 34.0°. The difference is 23.1°.

An animation of the mechanism, created in Fusion360, moving through its full range of motion is shown below.