ME 321 Homework


hw2 #5

Im having trouble figuring out what i2 dot 13, and j2 dot j3 are equivalent to for this one. I have theta 3 starting at the horizontal axis and going clockwise to link 3.

For i1 dot i3 i have cos(theta2-90+theta3) but I don't think that that is right
United States
Hi Kelsey,

I would recommend writing (i2, j2) and (i3, j3) in terms of (i, j), that is directions fixed in the ground, and then taking the dot products. You will probably find, for example, that

i2 . i3 = cos(theta2)*cos(theta3) - sin(theta2)*sin(theta3)
oh ok. But what about if you are dotting i2 with j3, it would be a different solution right?
United States
Yes, but the same procedure...