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Master Thesis - Reel-Looper System


The transported material in various industrial rolling processes (steel tape, plastic sheet or film, paper) needs to be maintained at a constant tensile stress level at any time of operation. Especially the material threading events, that come along with notable variations in geometry of the coiling system, generate huge perturbations of the tape force.

This diploma thesis, carried out by Walter BAUER, treats the mechanical design and assembly, the mathematical modelling, the determination of the model parameters as well as the design and implementation of a nonlinear MIMO control strategy for the reel-looper system.
The replacement (fishing line out of plastomer) for the handled material, also called tape in this context, is guided through a coiling system and attached to the reel on the right hand side of the experimental setup. The acting tape force is captured through a coil, which is mounted on top of a DMS load sensor. The movable looper coil and the revolving reel are both actuated by geared dc-motors. There are 2 d.o.f. in influencing the elongation of the tape within the coiling system thus.

By considering the adjustable geometry, the principle of mass conservation for the coiling system, the material properties of the tape and the equations of motion, a set of nonlinear ODEs of 6th order can be deduced. To achive a suitable set of ODEs for the model based control design, a system simplification is applied by neglecting the angular contact of the coils and the electric subsystems of the drives.

The choice of the variables {looper position, tape force} as system outputs for the simplified, nonlinear ODE system of 4th order leads to a dynamic system with an affine input structure (AI-system). A Full State Linearization for the MIMO-case yields to a linear, time-invariant and asymptotic stable closed loop MIMO control system in reachability form with the control outputs looper position and tape force. The static, nonlinear state feedback laws cause a decoupling of the outputs. A superimposed trajectory control permits the independent output tracking for sufficiently smooth reference trajectories.


Reel-Looper System

Reel-Looper System


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