Full Sheet Control Using Steerable Nips

This paper describes the mechatronics design, prototype testing, and control of a steerable nips component for paper path mechanisms in high-speed color printers and photocopiers. When placed upstream from the image transfer station along the paper path, this device precisely controls the longitudinal, lateral, and skew directions of papers sheets, as they arrive to the image transfer station. The paper also presents a complete kinematic and dynamic analysis of the paper sheet steering mechanism, which is validated by experimental results. It is shown that the dynamics of a sheet under the control of the steerable nips mechanism are nonlinear and subject to nonholonomic constraints. A feedback linearization control strategy that includes dynamic surface control is developed and implemented to control the sheet's position and angular orientation under the condition that the sheet's speed in the longitudinal direction remains positive at all times. Experimental results verify that the steerable nips mechanism under the proposed feedback linearization control strategy is able to meet or exceed all design performance requirements for deployment as a component of an actual printer paper path control mechanism.