Dieter Zöbel

The Deadlock problem: a classifying bibliography

The desire for a better utilisation of resources and an acceleration of computing introduced the concept of parallelism with all its difficulties. Soon the danger of eternal delays of processes was...

An Adaptive Software and Systems Architecture for Driver Assistance Systems based on Service Orientation

State of the art automotive software systems presume a static configuration of electronic control units and software components. Assuming that future Driver Assistance Systems (DAS) will deploy dynamically changing software configurations, the authors propose an approach towards an adaptive software and systems architecture for DAS. The paper focuses on systems, which assist the driver while backing up truck and trailer combinations. These systems are characterized by a high degree of distribution as well as a high level of heterogeneity and changeability even at runtime. In order to meet these demands, the authors suggest the usage of service orientation combined with software agents. The functional units of these systems are encapsulated in services which are dynamically orchestrated by the agents whenever the system changes. This paper describes the ideas of this approach using a real world example. It also names and classifies the scenarios of re-configuration. The article concludes with a lookout on the future work within this project.

Trajectory segmentation for the autonomous control of backward motion for truck and trailer

For logistics centers the disposition and dispatch of goods has reached a high standard of automation. However, the trucks and trailers bringing and taking wares are driven manually. This offers a enormous potential for automation for the yards of logistics centers. The availability of this potential is correlated to the autonomous forward and backward motion control for standard transportation vehicles. By an experimental system it has been shown that truck and trailer can be maneuvered autonomously at a high degree of precision. For purposes of safety it is necessary to guarantee that at any instant of time the vehicle is within some predefined area. Therefore, this paper introduces the principle of safe cover segments which are never left by the vehicle in motion and defines rules for the connection of such segments forming a safe corridor.

Resolution techniques and complexity results with deadlocks: a classifying and annotated bibliography

R e s o u r c e s h a r i n g was a bas ic c o n c e p t of m u l t i p r o c e s s i n g . But t h i s k i n d of i m p r o v e d u t i l i za t ion of r e s o u r c e s i n t r o d u c e d t h e d a n g e r of e t e r n a l d e l a y s . The p r o b l e m is i n h e r i t e d f rom t h e s t r a t e g y t h a t p r o c e s s e s may e x c l u s i v e l y hold r e s o u r c e s a n d a c q u i r e r e s o u r c e s in t h e s e q u e l of p r o c e s s i n g . This p h e n o m e n o n f i r s t d i s c o v e r e d in o p e r a t i n g s y s t e m s has b e e n named d e a d l o c k . For a lmos t t w e n t y y e a r s a lo t of a r t i c l e s c o n s i d e r i n g d e a d l o c k s a n d r e l a t e d p r o b l e m s h a v e b e e n p u b l i s h e d . In t h e mean t ime t h e a n a l o g o u s p h e n o m e n a w e r e d i s c o v e r e d a n d d i s c u s s e d fo r t h e r e s o u r c e m a n a g e m e n t in d a t a b a s e s , f o r r o u t i n g in commun ica t i on n e t w o r k s a n d f o r t h e s a f e t y of c o m m u n i c a t i o n p r o t o c o l s , t h a t is to s ay , in t h e c o n t e x t of d i s t r i b u t e d s y s t e m s . In t h e o r e t i c a l c o m p u t e r s c i e n c e d e a d l o c k s i t u a t i o n s a r e a n a l y s e d f o r P e t r i n e t s , c o m m u n i c a t i n g f i n i t e s t a t e m a c h i n e s a n d r e c e n t l y fo r V L S I d e s i g n . The h a r d n e s s of t h e p r o b l e m v a r i e s wi th t h e u n d e r l y i n g models a n d may r a n g e f r o m s u b l i n e a r i t y to N P c o m p l e t e n e s s o r e v e n u n d e c i d a b i l i t y . A s imilar v a r i e t y e x i s t s f o r t h e h o s t p r o b l e m s w h e r e t h e d e a d l o c k p r o b l e m is m a p p e d to. T h e y c a n be f o u n d in e l e m e n t a r y a r i t h m e t i c , a l g e b r a , g r a p h t h e o r y , logic e tc .

Minimum Parking Maneuvers for Articulated Vehicles with One-Axle Trailers

The kinematic behavior of articulated vehicles is complex and hard to control. This coincides with the perception of unskilled drivers, e.g., when they back up their car and the attached caravan. An integrated semi-automated driving assistance system would be very convenient for such situations. The realization of a system for backup assistance raises questions ranging from the theory of kinematics to the human-machine interaction. In this paper we focus on the fundamental question of the minimum maneuver for parallel parking. This question is discussed from its theoretical background to the practical integration into a respective assistance system

Conformance testing of priority inheritance protocols

The priority inversion problem was detected two decades ago (B.W. Lampson and D.D. Redell, 1980). The decisive ideas to cope with this problem were published one decade ago (1990). In the meantime, the vendors of operating systems and run-time systems have occupied this topic in providing certain protocols in order to avoid priority inversion. However, on closer inspection, there are considerable differences in the usage and the results of the various protocol interfaces. This is really pitiful in the scope of real time systems, because the application programmer wants to rely on certain predictability criteria, depending only on the kind of protocol used. Hence, we propose test suites to check the degree of conformance between the protocol proposed in the literature and the one implemented in a certain environment.

Maneuver-based assistance for backing up articulated vehicles

The kinematic behavior of articulated vehicles is complex and hard to control. This coincides with the perception or unskilled drivers, e.g. when they back up their vehicle and the attached camping trailer. Typically, such situations are stressful and adequate forms of assistance would be experienced as a welcome relief. This paper proposes a simple but efficient assistance system which on one hand focusses on the kinematic properties of certain maneuvers and on the other hand is modularized in a way that it can be retrofitted to any articulated vehicle with one-axle trailer. The assistance system has been implemented in a real vehicle and first experiences are already available.

SODA: Service-Oriented Architecture for Runtime Adaptive Driver Assistance Systems

Unlike state-of-the-art Driver Assistance Systems(DAS) upcoming technologies may not base on a static software and system architecture. This is especially true for DAS for truck and trailer combinations were the components needed are distributed over both parts of the articulated vehicle. As a truck might be connected to different trailers changes are very common. In order to handle these changes at runtime the usage of Service oriented Architecture (SOA) is a promising approach. Using this principle the functionalities are encapsulated into Services which are Re-Orchestrated whenever the system architecture changes. Since the Services in such a system run on small embedded units and are connected through specialized network systems existing SOA frameworks cannot be used here. This paper introduces SODA, a tailored SOA middleware and development process to design runtime adaptive DAS for truck and trailer combinations using Services.

Model-driven development of SOA-based driver assistance systems

This paper describes an approach towards model-driven development of SOA-based Driver Assistance Systems. In the field of assistance systems for truck and trailer combinations Service-oriented Architecture (SOA) is a promising approach to handle the heterogeneity and the high degree of distribution of these systems. Through connecting or disconnecting trailers the system is very likely to change at runtime which sets up the demand of runtime adaption. This paper illustrates a process model to use SoaML for modeling the components and architectures of these systems. Based on these models, model-driven runtime adaption can be carried out.

Pose detection in truck and trailer combinations for advanced driver assistance systems

The knowledge about relative orientations between truck and trailer is a vital prerequisite for driver assistance systems especially when dealing with safety improvements for this kind of vehicles. Yet, no adequate system solving this problem is available. A sensor system measuring this desired state information by an optical approach is presented in this paper. The sensor system is evaluated using a virtual testbed that has been developed for testing, diagnosis and proper configuration of the sensor.