Kinematic analysis:Application of defining path of joint

[marellasunny]

I understand that defining the path of a joint in a mechanism comes under the category of 'kinematic analysis'. I do not understand why engineers do this,when all they need to know is the path of the piston,piston velocity and piston acceleration(kinematic analysis). Take for example this 90 degree double piston mechanism -http://www.youtube.com/watch?v=X76HrTygEFQ


Also,is there a analytical method that exists to find the path of joints in a mechanism in motion? Deriving the curve mathematically seems tough.

 

[SteamKing]

Not every mechanism is a piston going back and forth. Some mechanisms are quite complicated to analyze, which is why engineers use software to aid in the analysis. It's similar to analyzing a structure. Not every structural analysis can be reduced to analyzing an equivalent beam or beams. Beyond a certain point, the math gets too tedious.