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State of the art high speed color printers require sheets being accurately positioned as they arrive to the image transfer station (ITS). This goal has been achieved by constructing and building a steerable nips mechanism, which is located upstream from the ITS. This mechanism consists of two rollers which not only rotate to advance the paper along the track, but also steer the paper in the yaw direction. This paper presents the design, experimental setup, system model, and the control law necessary to precisely correct for the lateral and angular positions of the sheet as well as to deliver it on time to the ITS. The system model is nonlinear and subject to four nonholonomic constraints. The control strategy used is based on linearization by state feedback with the addition of internal loops for the control of the process direction velocity and steering position of the rollers. This paper also provides a formal convergence analysis for the controller designed as well as the methodology required to tune it. The success of this mechatronic approach is corroborated through simulation and experimental results, which show that the controller is able to correct sheet errors under the condition that the page has nonzero initial and final longitudinal velocities.

Current approaches for high speed color printers require sheets be accurately positioned as they arrive to the image transfer station (ITS). This goal has been achieved by designing and building a steerable nip mechanism, which is located upstream from the ITS. This mechanism consists of two rollers that not only rotate to advance the paper along the track, but also steer the paper in the yaw direction. This paper briefly reviews the design and experimental setup of the system, and focuses on the design and analysis of a controller that precisely corrects the lateral, longitudinal, and angular positions of the sheet. The control strategy used is based on linearization by state feedback with the addition of internal loops for the local control of the actuators. This paper also provides a methodology to tune the controller parameters so that the desired performance specifications are met. The success of this mechatronic approach is corroborated through simulation and experimental results, which show that the system is able to correct sheet errors and meet all the performance specifications.

State of the art high speed color printers require sheets being accurately positioned as they arrive to the image transfer station (ITS). This goal has been achieved by constructing a steerable nips mechanism, which is located upstream from the ITS. This mechanism consists of two rollers which not only rotate to advance the paper along the track, but also steer the paper in the yaw direction. A recently developed nonlinear control strategy for the position of the sheet is briefly reviewed. The core of this paper focuses on the addition of a nonlinear observer used to estimate the longitudinal, lateral, and angular positions of a sheet, by detecting its motion along two of its perpendicular sides. The success of the approach presented is corroborated through simulations, in which the estimates from the extended Luenberger observer designed are used on a nonlinear feedback control strategy.