For the x-axis movement, the mechanism can be simplified as a four-bar mechanism as shown in Figure 4.1.

Figure 4.1

At first, we roughly measured the link length of a level-luffing crane from the picture, and set the length as the starting point. Then using MATLAB code to plot the position of the end point of link b where the charger will be put as the driving link a rotates.

Different plots are obtained by tuning the length parameters of the mechanism, and by comparing the linearity of the line, we are able to find the best link length parameters. Below is a diagrammatic depictions of the optimization. In Figure 4.2 we only show three different sets of parameters just to demonstrate the idea.

Figure 4.2

The link lengths that were calculate was: a=165, b=28.5,c=137.5 d =78, e=84 for the x-axis bar mechanism.

We then use the parameters to do a simulation as shown in Figure 4.3, from which we can see the trajectory of the mechanism perfectly linear for a certain range of motion. When the movement exceeds the linear range, the end of the mechanism will gradually go up.

Figure 4.3

For the y axis part, we also did a simulation showing the motion of the mechanism, in Figure 4.4.

Figure 4.4

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