Curvilinear barrier to rotate objects on a conveyor belt – analysis of the positioning process

The paper concerns numerical and experimental tests of the positioning process of cuboidal objects by an oblique barrier mounted above a belt conveyor. The new element of the presented research is the use of a barrier with variable curvature modelled using a quadratic b-spline function. In the positioning process model, the contact of the object with the barrier is identified by corners and edges, and with the conveyor supporting surface – by evenly distributed discrete points on the object's base. The tangential contact forces are represented by the Bengisu-Akay static friction model and LuGre dynamic model, and the normal forces – by nonlinear Kelvin model and Matlab Simscape model. The parameters of the contact models were selected based on experimental tests. In case of the LuGre model, the decisive impact on the parameters' selection is the object's movement stage occurring just after the object loses contact with the barrier, when hysteresis effects accompanying low sliding velocities are revealed. Research confirms the validity of using barriers with variable curvature, which ensure precise object positioning while minimizing the required workspace.