Robotic Assembly of Power Electronics

Abstract

The purpose of this Master's thesis was to investigate the possibility to perform a robotic assembly of power electronics for Siemens. The focus was on an inverter for a diesel-electric propulsion system used on vessels. The assembly is done manually today. This thesis was investigating which part of the assembly process that can be done with a robot.

It has been developed offline programming in a 3D graphical simulation system called Visual Components. Designing algorithms for the industrial robots was a major part of the thesis. Advancements were made because several parts had to be precisely positioned, as a consequence of many small assembly parts. Parts with exact geometry from the inverter was implemented in the simulation from a CAD program. KUKA robots were imported and set up in Visual Components just like they were at the Department.

Different grippers were developed and used in robotic assemblies and were adapted for the parts. As the testing got more advanced more grippers were designed and produced. The grippers were made for the available actuators, and were designed with the capability to grasp several components. This was planned out from the close/open capacity of the used actuators. With small difference on the actuators close/open capacity the grippers was only able to handle parts with similar form. Solidworks have been used as a modeling software to make grippers for the tasks.

The grippers were produced in different materials with corresponding characteristics and plastic, aluminum, and steel were tested. The grippers in aluminum were stronger than the one in plastic and faster to produce than the ones in steel. Therefore they were most favorable in this work.

Grippers designed in this thesis had either a purpose of lifting round objects as capacitors and the electric screwdriver or plate formed objects as Cu plates, a mounting plate, and capacitor welds.

After making the algorithms, post processing of files was done in Eclipse to create a file type the robot controller accepted. To test the post processor for restrictions it was tested on the two different KUKA robots KR 6 R900 sixx Agilus, and KR 120 R2500 pro.

The programs were executed in the robotic cells, and simulations from Visual Components were evaluated from the lab. The Videos which were made from the robot cell shows the results of all the programs from Visual Components. Results from this process led to scoping the robotic assembly to solutions for electric screw driving. More solution development for electric screw driving was done to assemble more parts because of the successful test and because the inverter is assembled with mainly screw operations.