PLC-based control of a Scara robot for 3D trajectories based on a chaotic attractor.

This thesis is the result of a project meant to use a PLC-controlled industrial robot to test the effectiveness at mixing liquids of different trajectories modelled after a 3D system based on a chaotic attractor. In order to conduct such tests we needed to spin a whisk inside a pot filled with water and dye while accurately following the chosen path to then measure how well the two fluids got mixed. To accomplish this we used a SCARA robot controlled trough a Beckoff PLC and to rotate the whisk at the required speed we also installed an additional motor at the end of the robot’s arm. Through the virtual camming feature of the PLC the inverse kinematics of the robot can be handled by the functions inside the system’s libraries and so we programmed it to directly receive and follow a trajectory defined in Cartesian space. This allowed for a frictionless transition from the generation of a trajectory to implementation. The PLC’s software also includes the tools required to measure the position over time of the robot and thus allowed us to evaluate the precision of our movement compared to the desired trajectory and prove that it can follow it with good accuracy.