Instant centre of rotation
（重定向自Instantaneous center of rotation）
![Sketch 1: Instantaneous centre P of a moving plane](/Images/godic/202501/20/Mechanism_analysis2500.png")
![Sketch 2: Pole of a planar displacement](/Images/godic/202501/20/Pole-object-A1-A22500.png")
![Sketch 3: Rolling wheel.](/Images/godic/202501/20/Wheelrotation2500.png")
![Sketch 4: Example relative centre of rotation. Two bodies in contact at C, one rotating about A and the other about B must have a relative centre of rotation somewhere along the line AB. Since the parts cannot interpenetrate the relative rotation centre must also be along the normal direction to the contact and through C. The only possible solution is if the relative centre is at D.](/Images/godic/202501/20/RelativeCenterOfRotation2500.png")
The instant centre of rotation, also called instantaneous velocity center, or also instantaneous centre or instant centre, is the point fixed to a body undergoing planar movement that has zero velocity at a particular instant of time. At this instant, the velocity vectors of the trajectories of other points in the body generate a circular field around this point which is identical to what is generated by a pure rotation.