456 research outputs found
Deadline Miss Early Detection Method for DAG Tasks Considering Variable Execution Time
No full textAutonomous driving systems must guarantee safety, which requires strict real-time performance. A series of processes, from sensor data input to vehicle control command output, must be completed by the end-to-end deadline. If a deadline miss occurs, the system must quickly transition to a safe state. To improve safety, an early detection method for deadline misses was proposed. The proposed method represents the autonomous driving system as a directed acyclic graph (DAG) with a mixture of timer-driven and event-driven nodes. It assigns appropriate time constraints for each node based on the end-to-end deadline. However, the existing methods assume the worst-case execution time (WCET) for calculating the time constraints of each node and do not consider the execution time variation of nodes, making the detection of deadline misses pessimistic. This paper proposes a deadline miss early detection method to determine the possibility of deadline misses quantitatively at the beginning of each node execution in a DAG task. It calculates the time constraints of each node using probabilistic execution time, which treats execution time as a random variable. Experimental evaluation shows that the proposed method reduces pessimism, which is a problem of conventional methods using WCET, and then achieves more accurate early detection of deadline misses. The evaluation also indicates that the execution time of static analysis required for deadline miss early detection is within a practical level
IDF-Autoware: Integrated Development Framework for ROS-Based Self-Driving Systems Using MATLAB/Simulink
No full textThis paper proposes an integrated development framework that enables co-simulation and operation of a Robot Operating System (ROS)-based self-driving system using MATLAB/Simulink (IDF-Autoware). The management of self-driving systems is becoming more complex as the development of self-driving technology progresses. One approach to the development of self-driving systems is the use of ROS; however, the system used in the automotive industry is typically designed using MATLAB/Simulink, which can simulate and evaluate the models used for self-driving. These models are incompatible with ROS-based systems. To allow the two to be used in tandem, it is necessary to rewrite the C++ code and incorporate them into the ROS-based system, which makes development inefficient. Therefore, the proposed framework allows models created using MATLAB/Simulink to be used in a ROS-based self-driving system, thereby improving development efficiency. Furthermore, our evaluations of the proposed framework demonstrated its practical potential
Extended mapping algorithm based on modularity from synchronous block diagrams to AUTOSAR runnables
No full textDemo Abstract: Co-simulation Framework for Autonomous Driving Systems with MATLAB/Simulink
No full textWork in Progress: Considering Heuristic Scheduling for NoC-Based Clustered Many-Core Processor Using LET Model
No full text
Deadline Miss Early Detection Method for Mixed Timer-Driven and Event-Driven DAG Tasks
No full textSelf-driving systems have a hard real-time nature, and the control commands of the vehicle must be output before the end-to-end deadline using sufficiently new data. It must also have the functionality to quickly shift to a safe state in the event of a deadline miss. However, the current self-driving system can only detect a deadline miss at the end of the process. To further improve safety, a method for detecting the possibility of a deadline miss in the middle of the process is required. Therefore, we represent such a real-time system as a mixed timer-driven and event-driven directed acyclic graph (DAG) and propose an early detection method for deadline misses by deriving a time constraint for each node. The experimental evaluation shows that the proposed method can detect deadline misses early for various scheduling algorithms. It also shows that the deadline miss ratio can be reduced by prioritizing the scheduling of jobs with a small margin to the time constraint determined using the proposed method for each job
Seasonal variations in planktonic foraminiferal flux and oxygen isotopic composition in the western North Pacific : Implications for paleoceanographic reconstruction
No full textThe oxygen isotopic composition (delta O-18) of planktonic foraminiferal shells in seafloor sediment provides information on past surface oceanography. Knowledge of seasonal and depth habitat, as well as the delta O-18 disequilibrium (vital effect), is essential to constrain the interpretation of sedimentary delta O-18. Here, we present a 1-year time series of planktonic foraminiferal shell fluxes and delta(18)Ofrom a sediment trap moored in the northwestern margin of the North Pacific. The vital effect and calcification depth for four species were estimated by comparing shell delta O-18 and the predicted values of equilibrium calcite calculated from temperature and estimated delta O-18 in seawater. Six major species (Neogloboquadrina incompta, Nedgloboquadrina dutertrei, Neogloboquadrina pachyderma, Globigerina quinqueloba, Globigerina bulloides, and Globorotalia scitula) constituted 97% of the total foraminiferal flux. Most major species showed large fluxes in June and December, corresponding to periods of the development and disruption of the seasonal thermocline, implying the importance of nutrient injection and/or circulation for foraminiferal fluxes. Additional peaks in N. dutertrei and N. pachyderma were observed in August. The seasonal successions of foraminiferal fluxes corresponded to surface ocean stratification conditions and food availability, which are closely related to circulation of local currents. Vital effect estimations suggest that shells calcified in equilibrium for G. bulloides and N. pachyderma [sinistral (s)1 and with a -0.7% offset for N. dutertrei [dextral (d)], a -1.0%, offset for N. incompta (d), and a -03% offset for N. pachyderma (d). The calculation of flux-weighted delta O-18 values reveals that the sedimentary delta O-18 values of G. bulloides, N. dutertrei (d), and N. incompta (d) reflect surface temperature in winter season, and those of N. pachyderma (s) and N. pachyderma (d) reflect summer and annual mean subsurface temperature, respectively. The shallow calcification depths for the four species suggest that delta O-18 between different species (Delta delta O-18) in the western North Pacific does not work for reconstructing past stratification conditions, unlike in other regions. Rather, the delta O-18 between N. pachyderma (s) and G. bulloides, N. dutertrei (d) or N. incompta (d) may be a more suitable proxy for past seasonality. (C) 2013 Elsevier B.V. All rights reserved
- …
