In case of a winding machine there are several problems to be solved to achieve a stable controlled winding process. At first rigid mechanical construction should be designed to reduce vibrations caused errors. The winded material should be tight (with given tolerance) to avoid it getting unwound or fallen of the rolls. Therefore it should be under an appropriate magnitude of constant tension. It is evident that the material should not be torn away, so it is required to measure the tension that is applied to the material web. Besides, the rotating material rolls diameter, thus their moment of inertia is continuously changing, and this is an additional challenge in control design.
The methodologies for solving the above mentioned problems require both experience and interdisciplinary knowledge in engineering science such as strength of materials, mechanics, electronics and control techniques. Shortly formulated the methodologies are the following. The measurement of the current material velocity on both shafts obtained with the help of encoders built in the motors, which constantly reports the current angular speed as well as position. Material web tightness is measured with the so called sprung dancer roll designed in between the winder shafts, which has been equipped with sensors. Tightness can be measured also indirectly with motor torques substituted to the appropriate mechanical equations. Ratio of the shaft speeds gives the ratio of the radii thus the ratio of the square root of the moments of inertia. Moreover, the starting radii ratio gives the reciprocal ratio of the final ratio, which helps the control determining the stopping point at the end of the winding process. The above mentioned are implemented in the mechanical model and controller logic which are detailed in the final project.
The results of the project showed that the simplified mechanical construction of a winding machine can be approximated well with 2D equations, giving the opportunity to calculate system variables in real-time for smooth control. An other outcome of the project is two complete mechanical designs with additional calculations and simulations that validate that the constructions proper for the desired usage.