This example is how to move the box from position p1 to final position p4 during t1 to t4
Moving object from position 1 to position 4
Solution: First we need to calculate 
at t1, t2, t3, t4. Then we need to calculate the position of the links. This kind of problem can be called inverse kinematics. We should be careful that during motion no accident happens. Given s at each moment determines the position and orientation of all links.
Forward position problem
Fixed parameters of the mechanisms values of joint variables will determine position and orientations of all links.
Inverse position problem
Fixed bars of the mechanisms position, and orientations of end effector will determine the values of joint variables.
Simple example with planar 2R
2R Manipulator
Sketching the position
Example1:
This is a numerical example for 2 planar:
The solution drawn in SolidWorks
