Andreas Barthels

Predicting Parking Lot Occupancy in Vehicular Ad Hoc Networks

The search for free parking places is a promising application for vehicular ad hoc networks (VANETs). In order to guide drivers to a free parking place at their destination, it is necessary to estimate the occupancy state of the parking lots within the destination area at time of arrival. In this paper, we present a model to predict parking lot occupancy based on information exchanged among vehicles. In particular, our model takes the age of received parking lot information and the time needed to arrive at a certain parking lot into account and estimates the future parking situation at time of arrival. It is based on queueing theory and uses a continuous-time homogeneous Markov model. We have evaluated the model in a simulation study based on a detailed model of the city of Brunswick, Germany.

A model for sequence based power management in cyber physical systems

This paper develops a model for operating system level power management in cyber physical systems. The core part is a transducing mechanism, forming physical inputs into functional state sequences. Each functional state transition then is allowed to switch in between power management plans. A power management plan is modeled as a directed graph over power states and functional jobs together with timing conditions. Different optimization problems for designing these plans according to scheduling requirements, and for maximizing energy savings under both constrained management complexity and constrained supply voltage stability are presented.

Topology and Design Optimization of a 14 V Automotive Power Net Using a Modified Discrete PSO in a Physical Simulation

In the last years, hydraulic powered chassis control systems have been replaced by electrical systems due to efficiency reasons. Additionally, more and more comfort electronics have been integrated. These circumstances have lead to a high power demand in todays automotive power nets. For this reason, voltage stability has become an important design criterion of the power net. This paper describes a simulation based method to optimize the power net topology and the dimensioning of components with regard to voltage stability requirements. A Modified Discrete Particle Swarm Optimization is used in combination with a physical power net simulation. In order to optimize the topology itself, a tool flow for an automated change of the simulation model is presented. To achieve best possible performance, the influence of the configuration parameters on the algorithm performance is evaluated and appropriate parameters are chosen for the given problem. Finally, exemplary optimization results are shown by pointing out optimal topologies for different constraints of the minimum terminal voltage.

Design optimization of a 14 V automotive power net using a parallelized DIRECT algorithm in a physical simulation

The high power demand of electrical components in cars and the associated complexity of the 14 V power net have steadily increased in recent years. An important design criterion of the power net is the voltage stability during peak loads. This paper describes a simulation-based optimization method to fulfill the voltage stability requirements in a minimum-weight configuration of the power net. The method is applied to different power net topologies which are configured using a mixture of discrete and continuous parameters. Finally, the performance of the optimization algorithm as well as the optimization results are presented and evaluated.

A layered interface-adaptation architecture for distributed component-based systems

The heterogeneous and distributed nature of automotive software systems demands for flexible software components which can operate in different environments. In this context, interface adaptation is a promising approach to achieve the flexibility without directly changing the respective components. Recent work uses finite-state machines for behavioural adapter modelling and code generation. Based upon such a state-based approach, we developed a new hierarchical adapter architecture which enables the separation of global and local adaptations. Dividing the adapter model into two parts results in a much smaller state machine and makes the adapter more independent from behavioural changes of the adapted components. Our approach relies on an abstract interface and adapter model and enables the generation of executable adapter code. A key goal of the modelling approach is the reuse of existing interface description languages and respective code generators. The approach is completely tool-supported and was evaluated for a Linux-based automotive operating system. We show a practical realization of the models using an automotive use case. Adaptation of interfaces using a new layered approach.The approach divides global from local adaptations.Presentation of an execution and code-generation architecture.State-machine reduction and robust adapter execution.Evaluation for a Linux-based automotive infotainment system.

An architecture for power management in automotive systems

This paper presents an architectural model for power management in automotive systems. It is based on recent advances in cyber physical and cybernetic control systems. Based upon a previous model of power management, formal interactions in between a hierarchical structure are characterized. In the architecture, strategic decisions allow coordinated adjusting of power management plans as well as local autonomy in subsystem scope.

An automotive specific MILP model targeting power-aware function partitioning

With customer demand for more comfort and safety features, the amount of software and electronics in a car is steadily growing. In order to cope with the corresponding increased power consumption of the E/E (electric/electronic) architecture, various power saving techniques were developed to turn off functions, electronic control units (ECUs), or even whole bus systems when they are temporarily not needed. However, the potential of these techniques is highly dependent on the mapping of the vehicle functions to the distributed network of ECUs. This paper presents a mixed-integer linear programming (MILP) approach that supports the designer in an early phase of the automotive E/E development process to find an optimal function partitioning with respect to energy-efficiency. While various MILP-based task to processor mapping concepts have been investigated before, the contribution of this paper brings forward an automotive domain specific MILP model with a cost function that is based on the power consumption for computation and communication of the overall system. Furthermore, the schedulability of the partitions is here taken into account. The approach was integrated into an existing E/E design space exploration framework and evaluated for feasibility and scalability. The results reflect the potential gain of a power-aware function partitioning.

A Design Space Exploration Framework for Automotive Embedded Systems and their Power Management

The E/E (electric/electronic) architecture of a modern vehicle is a complex distributed system, where up to 80 electronic control units (ECUs), interconnected by several communication buses, need to collaborate with each other in order to implement the various comfort and safety features. The presented E/E design space exploration framework supports engineers during the development process of new E/E architectures by providing a graphical modeling and simulation environment with an interactive visualization of simulation-based results. Furthermore, it contains an advanced business logic which administrates the modeling, storing, retrieving and cloning of evaluation sessions consisting of complex experiments. Due to a high-level modeling approach, future architectures can be evaluated in respect to power consumption and performance values already in an early stage of the design process and design alternatives can be easily compared with each other.

ITE-Sim: A simulator and power evaluation framework for electric/electronic architectures

This paper presents a novel electric/electronic (E/E) architecture simulator that allows the evaluation of design alternatives during early stages of the automotive development process. The simulation framework performs a joint power/performance evaluation for different partitionings of functional chains on a given multi-ECU technical architecture. The high-level modeling approach results in a short simulation runtime, which allows many different architectures to be explored. The simulator provides information about the power consumption, utilization values and timing information for processing and communication resources. Furthermore, it is possible to simulate and evaluate various power management concepts.

PREcup-1: An embedded system platform for prototyping ECU power management

This paper presents an embedded system platform for investigating power management methods relevant to future automotive systems. The platform is built around an ARM Cortex A8 System on Chip (SoC). It allows for measuring the power consumption of the SoC and its peripherals. The SoC has a defined set of power states, namely frequency and voltage operating points, as well as retention and off-modes. During runtime, the power states are managed by a novel Linux-based scheduler. It allows the execution of plans combining both timed software and power state switches. The design is evaluated using a single ECU and its local scheduling.