Modular robotic workcells enable a production system to be adapted to different products and processes without extensive changes to the entire workcell. This thesis addresses the further development of a previously designed modular screwdriving system for a robotic workcell in the Humanoid and Cognitive Robotics Laboratory at the Jožef Stefan Institute. The aim was to create a virtual model of the workcell and to develop and test prototype control of an additional translational degree of freedom for the previously designed three-screwdriver system. In this system, a single shared drive actuator moves between the screwdrivers. This enables the robot to select the appropriate screwdriver between screwdriving operations without setting down the entire process tool.
As part of the thesis, a digital model of the complete robotic workcell was assembled in RViz 2 from the available digital models of the individual components. Coordinate relationships between the components were defined, and object state changes and previously recorded robot trajectories were visualized. A Raspberry Pi 4, a RevPi Connect 4, and a TB6600 stepper motor driver were selected for prototype control of the additional translational degree of freedom for the horizontal movement of the shared drive actuator between the three screwdrivers. The measurement subsystem, comprising an RLS LA11 readhead and a SAS10 magnetic scale, was connected to the drive subsystem through ROS 2 nodes running in Docker containers.
Positioning was evaluated using twelve movements between target positions of 80 and 160 mm. The mean absolute error was below 0.1 mm at both target positions. The results indicate that basic closed-loop positioning functioned in the test setup. Since the same measurement system was used for both control and evaluation, the absolute accuracy and the operation of the fully assembled screwdriving system must still be verified using an independent measuring instrument and under the intended mechanical load.
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