Andreas Schierl

Abstract Specification of the UBIFS File System for Flash Memory

Today we see an increasing demand for flash memory because it has certain advantages like resistance against kinetic shock. However, reliable data storage also requires a specialized file system knowing and handling the limitations of flash memory. This paper develops a formal, abstract model for the UBIFS flash file system, which has recently been included in the Linux kernel. We develop formal specifications for the core components of the file system: the inode-based file store, the flash index, its cached copy in the RAM and the journal to save the differences. Based on these data structures we give an abstract specification of the interface operations of UBIFS and prove some of the most important properties using the interactive verification system KIV.

The Robotics API: An object-oriented framework for modeling industrial robotics applications

During the last two decades, software development has evolved continuously into an engineering discipline with systematic use of methods and tools to model and implement software. For example, object-oriented analysis and design is structuring software models according to real-life objects of the problem domain and their relations. However, the industrial robotics domain is still dominated by old-style, imperative robot programming languages, making software development difficult and expensive. For this reason, we introduce the object-oriented Robotics Application Programming Interface (Robotics API) for developing software for industrial robotic applications. The Robotics API offers an abstract, extensible domain model and provides common functionality, which can be easily used by application developers. The advantages of the Robotics API are illustrated with an application example.

Interfacing industrial robots using Realtime Primitives

Today, most industrial robots are interfaced using text-based programming languages. These languages offer the possibility to declare robotic-specific data types, to specify simple motions, and to interact with tools and sensors via I/O operations. While tailored to the underlying robot controller, they usually only offer a fixed and controller-specific set of possible instructions. The specification of complex motions, the synchronization of cooperating robots and the advanced use of sensors is often very difficult or not even feasible. To overcome these limitations, this paper presents a generic and extensible interface for industrial robots, the Realtime Primitives Interface, as part of a larger software architecture. It allows a flexible specification of complex control instructions and can facilitate the development of sustainable robot controllers. The advantages of this approach are illustrated with several examples.

Developing Self-Organizing Robotic Cells Using Organic Computing Principles

Nowadays industrial robotics applications, which are often designed and planned with a huge amount of effort, have a fixed behavior during runtime and cannot react to changes in their environment. Failures can hardly be compensated and often can only be repaired by human involvement. The idea of Organic Computing is to enable systems to possess life-like properties, such as self-organizing or self-healing. In this chapter we present a layered architecture to bring these two worlds together. Further it is discussed what are the requirements of the respective layers to allow to engineer self-x properties into such systems. The presented approach allows for developing self-organizing robotic applications that are able to take advantage of Organic Computing principles and therefore are more robust and flexible during runtime.

Environment-aware proximity detection with capacitive sensors for human-robot-interaction

Recently, the need for safe human-robot-interaction has become increasingly important, and with it the requirement to reliably detect persons in the workspace of a robot. Capacitive sensors mounted to the robot structure can be used to measure the presence of conductive objects and, hence, allow the detection of persons. However, various objects in the workspace can influence capacitive sensor measurements. Thus, we propose to record an environment model containing the expected sensor values for relevant robot poses. Using this model, distance estimation and real-time reaction can be performed even in the presence of additional conductive objects in the workspace. A demonstration of our approach was shown at the Hannover Messe 2015.

Flexible and continuous execution of real-time critical robotic tasks

Today, industrial robots are usually programmed using specialised programming languages, different for every robot manufacturer. These languages provide good usability, because they are tailored to the functionality traditionally offered by robots. However, these languages are reaching their limits with the growing integration of sensors or multiple robot systems. Therefore, we propose an architecture based on the separation of application control and the execution of real-time robotic tasks. This article describes a flexible and extensible interface for the specification and continuous execution of robotic tasks.

Managing extensibility and maintainability of industrial robotics software

As neither the set of robotics devices nor the operations they can execute is fixed, a software framework for robotics should be extensible. Moreover, as the environment the robots work in changes, the application controlling them must be easily adaptable to changing requirements. When this can be achieved at run-time, it leads to a continuous evolution of robotics software. This paper presents an object-oriented software framework, the Java-based Robotics API, that facilitates extensibility with code reuse. By integrating the framework into the dynamic module system OSGi, it is possible to continuously evolve a robotics application (including its real-time capable parts).

Instantaneous switching between real-time commands for continuous execution of complex robotic tasks

An application program for one or even several industrial robots usually consists of a number of disjoint commands, with each command controlling the robot to perform a certain task like motions or tool interactions. Sometimes it is desirable to be able to switch from one such command to another command with time guarantees for the switching progress, e.g. for blending one motion into another. In this paper we propose an approach to achieve this with two separate commands, where the second command can be created while the first is already being executed.

On Structure and Distribution of Software for Mobile Manipulators

Complex robot applications or the cooperation of multiple mobile robots are use cases of increasing popularity where software distribution becomes important. When developing mobile robot systems and applications, software structure and distribution has to be considered on various levels, with effects on the organization and exchange of data. With respect to structure and distribution, this work proposes to distinguish between real-time level, system level and application level. Ways of structuring the software, as well as advantages and disadvantages of distribution on each level are analyzed. Moreover, examples are given how this structure and distribution can be realized in the robotics frameworks OROCOS, ROS and the Robotics API. The results are demonstrated using a case study of two cooperating KUKA youBots handing over a work-piece while in motion, which is shown both in simulation and in a real world setup.

Decentralized Coordination of Heterogeneous Ensembles Using Jadex

Multi-agent systems can be a viable choice for realizing self-organizing systems consisting of reconfigurable software components. We present a real-world system consisting of heterogeneous air and ground robots whose behavior and coordination is orchestrated by a MAS in a decentralized manner. The system is able to cooperatively transport largescale measuring equipment and is used for environmental observation, such as in-situ measuring of temperature.