Theory of Machine
The fundamental equation for correct steering is (where φ and α = Angle through which the axis of the outer wheel and inner wheel turns respectively, c = Distance between the pivots of the front axles, and d = Wheel base)
The two rigid links have no linear velocity relative to each other at the instantaneous centre.
A rigid link rotates instantaneously relative to another link at the instantaneous centre for the configuration of the mechanism considered.
The velocity of the instantaneous centre relative to any third rigid link is same whether the instantaneous centre is regarded as a point on the first rigid link or on the second rigid link.