The instant center can be considered the limiting case of the pole of a planar displacement.
The planar displacement of … See more

Consider the planar movement of a circular wheel rolling without slipping on a linear road; see sketch 3. The wheel rotates around its axis M, which translates in a direction parallel to the road. The point of contact P o… See more

If two planar rigid bodies are in contact, and each body has its own distinct center of rotation, then the relative center of rotation between the bodies has to lie somewhere on the line connecting the two centers. As a result, sinc… See more

Sketch 1 above shows a four-bar linkage where a number of instant centers of rotation are illustrated. The rigid body noted by the letters BAC is connected with links P1-A and P2-B to a base or frame.
The three … See more

In biomechanical research the instant center of rotation is observed for the functioning of the joints in the upper and lower extremities. For example, in analysing the knee, ankle, or shoulder joints. Such knowl… See more