Currently my research interests concentrate in autonomous mobile robots (AMRs) and computational intelligence (fuzzy logic, genetic algorithms). Also my previous research interests in microelectronics is included in this framework. Since I studied computer science and electrical engineering I combine the theoretical aspects of cognition and intelligence phenomena with practical applications for robots. To electrical engineers my work seems highly theoretical and for computer scientists too much practical. Though these two aspects may seem contradicting, there synthesis leads to desirable results. The following list gives an overview of the main topics. Please look at my publication site for detailed papers to the topics.
is more or less a synonym for acquiring semantic information from sensor streams. This could be textual information out of indoor environment e.g. reading door plates but also textual information from objects. A service robot should distinguish between e.g. normal beer and alcohol free beer. This is difficult since the bottles look very similar but could be easily distinguish while reading the labels.
Fast moving or high speed autonomous mobile robotics.
2003, i build a robot (KURT2) that drives with 4.0 m/s in our corridor (reliable controlled !!) which was during that time the fastest indoor robot of the world. The robot is controlled by some special real-time algorithm. The main sensor is the 3D laserscanner and wheel encoders. More informations can be found at the high speed KURT2 homepage.
2D and 3D World modeling
A world model is a (some times fuzzy) plan of the environment of the robot. I developed a 3D world model format for administrative buildings. The format is used to reposition the robot when it loses his position and to plan missions and actions. The job scheduler uses also the world model to build its optimization function. In buildings repositioning is usually done at the end or beginning of a corridor. Doors especially door frames could also be found by the sensor evaluation routines and are used as additional natural landmarks. My world model is also the fundament of several other modules. 2D and 3D descriptions (e.g. VRML) are generated from this building description for the human machine interface HMI. Also 2D grids for high speed robot simulation and robot behavior prediction (robot behavior anticipation) are generated. The functionally orientated world-, robot- and sensor-modeling is also important for designing different behaviors of the robot.
With our IAIS 3D laser scanner it is now possible to accquire 3D information completely automatic and to build 3D maps from the environement (SLAM). Extracting and labeling objects from the 3D data e.g. for symbol grounding or symbol anchoring is an challenge task for robots also with the kinect.
Robot control architectures and robot hardware
In 1995 i specify a control architecture and hardware of the MORIA robot and the ARIADNE service robots Marvin, Odysseus and Thor . This includes path and action planning and navigation behaviors. The navigation behavior of the MORIA robot which is based on recurrent fuzzy systems was prized with the intelligence award at the FUZZ/IEEE 1995 in Yokohama, Japan. Today we use ROS to control our robots.
Computational Intelligence / Machine learning
This mainly includes fuzzy logic / control and genetic algorithm but also standard machine learning, neural networks and deep learning. I combine fuzzy logic controller and genetic algorithm for the automatic design of robot control behaviors (Evolutionary Robotics) or the combination of different behaviors. I am also interested in theoretical questions e.g. the difference between fuzzy logic and probabilistic approaches, Simulated Annealing and genetic algorithms etc..
This general topic influences the robot architecture and especially the design and implementation of algorithms (e.g. for navigation, planing, World modeling, sensor evaluation and fusion ...). Real-time control includes also real-time communication. To achieve this, the ARIADNE robots had one main PC and two Microcontrollers which share several informations. I like the modified linux kernel RT-linux and ROS to achieve real-time capabilities. The servos from the 3D scanner are controlled by RT-linux
Sensors and sensor fusion
Information sensing is the basis for autonomous navigation. The robots may use ultra sonic, laser range finder or cameras. Currently I prefer laser range finder and wheel encoders as main sensors for robot navigation assisted by internal or external cameras and ultra sonic sensors. Further sensors e.g. smell sensors are added on demand. I developed an algorithm for information extraction (e.g. different directions) and obstacle avoidance (humans, other robots) which evaluates a complete laser scan of 361 (Sick) or 500 (Schmersal) values in O(n) (linear with the number of sensor points). On the base of a 2D laser range finder i also designed and realized a cheap, precise, reliable and real-time capable 3D laser range finder.
Navigation and planning
Navigation and planning are important for the robot to do useful things like post delivery. Especially the integration of high-level reasoning and low-level execution and the designing of robust behavior modules is important. I developed different behaviors based on a recurrent fuzzy system that are robust behavior modules. The compositional rule of inference is my favorite method for the integration of different behavior blocks as well as high level planning and low-level execution. New behaviors could be added modularly as new fuzzy rules or as a block of fuzzy rules through the system. I used a fuzzy case tool that I developed on my own for developing the robot behavior. Standard graph search algorithms are used to find the robot paths and the actions (e.g. opening a door) in the world model.
Human Machine Interfaces (HMI)
Since my robots work really autonomously, they do not have to be teleoperated. But the robots need an adequate user interface because they have to be controlled, ordered, monitored or maintained by humans. Internet technologies, e.g. client/server models, offer the possibility to realize such an user interface highly comfortable for the user, because the clients (e.g. Netscape Navigator or MS Internet Explorer) work on different platforms with the user's operating system and known environment. So, currently I implement a server with the following features:
Spatial Cognition in indoor environments
This includes spatial representations and actions, representation and activation of route knowledge etc. In principal this means the analysis of intelligence phenomena. In real world applications only a few aspects of the whole theoretical framework are realized. Currently work concentrates in the automatic generation of (recurrent) fuzzy rule based systems for service robots. This is done with a distributed Genetic Algorithm on a standard computer network. The fuzzy rules should be more or less equal to rule description of human experts.
High disposability, reliability and robot security
Today in the context of internet/intranet and client/server technologies security aspects gain increasing interest. Therefore I added the following security features to our system: