Mobility calculation

The Mechanisms for our design consist of two similar four bars. Therefore, to find the mobility of our mechanism, we need to calculate the Grashof condition for one four bar. The Grashof condition is the following equation:

• S+L<P+Q

Where S is the length of the smallest link, L is the length of the longest link, and P and Q are the lengths of the other two links. Plugging in the lengths of our links, we result in the

• 135+240<145+235 = 375<380

The Grashof condition is true. This means that theoretically, the smallest link should be able to rotate a full 360 degrees. However, due to physical constraints of our design, the links cannot fully rotate.

Position analysis

In our mechanism, we want the cups of our mechanism to be close to on top of each other. This is because we want to pour water from the top cup into the bottom cup. I found the position of the cups using the position analysis formula for four bars. Using the four bar equations, I was able to find the angle of link 2 and link 3 with respect to the x axis. We also know the length of link 2 and where the cup is with respect to link 3. To find the x and y positions for the mechanism, we used these equations:

• x=L2*cos(theta2)+LC3*cos(theta3+thetaC)
• y=L2*sin(theta2)+LC3*sin(theta3+thetaC)

Where L2 is the length of link 2, LC3 is the length from the cup to the joint connecting links 2 and 3, theta2 and theta 3 is the angle of links 2 and 3 from the x axis, and thetaC is the angle between link 3 and the vector that points toward the cup from joint 23. In Appendix B is the animation of where the cups are in respect to one another in time. The animation is also shown below

 Velocity analysis

In our mechanism, we wanted to slow down the velocity of the links when the cups started to go on top of one another. This position is reached when the the second link is in an angle of either less than 90 or greater than 200 degrees. Therefore, we decided to lower the speed at which link 2 spins to be half of the original velocity whenever we detect the links approaching those angles. We found the angular velocity using the angular velocity equations for four bars. The plots of the velocity of links 3 and 4 are shown in Appendix C and are shown below.

In Appendix D is the full code that calculates the position and velocity analysis