Doctoral colloquium by Sergey Alatartsev on 7.7.2015
On Tuesday, July 7, 2015 at 4 p.m. in building 29, room 301 the doctoral colloquium for obtaining the academic degree DOKTORINGENIEUR (Dr.-Ing.)
of Mr. Sergey Alatartsev (Diplom-Ingenieur), doctoral candidate at the Faculty of Computer Science, Institute of Distributed Systems, will take place.
The topic of the dissertation is "Robot Trajectory Optimization for Relaxed Effective Tasks".
Industrial robots are flexible machines that are currently used in a wide variety of production areas. Their workflow mainly consists of two alternating phases. The first phase calculates effective movements required to perform a task, such as welding. In the second phase, supporting movements are determined, which are required for the movement between two tasks. However, especially in the first phase, it is possible that, for example, the robot's tool may have a certain distance or angle clearance during welding. This freedom is often neglected and robots are programmed manually according to the programmer's intuition. Nevertheless, this margin can be used as an additional degree of freedom for the optimization of the robot trajectory. In this paper, we present a formalization of this freedom for effective tasks. We refer to an effective task with a formalized execution freedom as a relaxed effective task.
Having an infinite number of ways to perform a task gives rise to various research questions:
- How to optimize an entry point sequence for relaxed effective tasks?
- How to find initial congurations of the robot for these tasks?
- How to optimize a robot trajectory for a specific relaxed task?
We present a concept that is able to solve the three problems in three separate components. Used in combination with each other, or with other state of the art approaches, the calculation of the optimized robot trajectory is possible.
The first component considers the problem of finding a sequence for effective tasks and their entry points. This problem is known as the "Traveling Salesman Problem with Neighborhoods" (TSPN), where the goal is to find a tour through a set of neighborhoods. We introduce "Constricting Insertion Heuristics" for constructing a tour and "Constricting 3-Opt" for optimizing the tour. In the second component, the motion path has to be adapted and initial configurations for the robot have to be found. This problem is known as the "Touring-a-Sequence-of-Polygons Problem" (TPP), where a tour is to be found through a given sequence of regions. We introduce a modification of the Rubber-Band Algorithm (RBA) and call this extension "Nested RBA". The optimization of robot trajectories in the third component is also represented as TPP. Nevertheless, in contrast to the classical RBA, where regions are constrained by a polyline, we present an extension of the RBA called "Smoothed RBA", where regions are constrained by a smooth curve, which leads to a minimum cost robot trajectory.
Doctoral committee:
- Chairman: Prof. Dr. Rudolf Kruse, FIN-IWS
- 1st appraiser:: Prof. Dr. Frank Ortmeier, FIN-IVS, AG Software Engineering
- 2nd appraiser: Prof. Dr. Nikos Aspragathos, University of Patras, Greece
- 3rd appraiser: Prof. Dr. Dmitry Berenson, Worcester Polytechnic Institute, USA
- 4th appraiser: Prof. Dr. Iacopo Gentilini, Embry-Riddle Aeronautical University, USA
- Member: Jun.-Prof. Dr. Sebastian Zug, FIN-IVS, AG Emmbedded Smart Systems
Interested parties are cordially invited.