Scheduling Algorithms for Multiprogramming in a Hard-Real-Time Environment
Journal of the ACM (JACM)
Elastic Scheduling for Flexible Workload Management
IEEE Transactions on Computers
A Utilization Bound for Aperiodic Tasks and Priority Driven Scheduling
IEEE Transactions on Computers
Generalized rate monotonic schedulability bounds using relative period ratios
Information Processing Letters
A Gravitational Task Model for Target Sensitive Real-Time Applications
ECRTS '08 Proceedings of the 2008 Euromicro Conference on Real-Time Systems
A Norm Approach for the Partitioned EDF Scheduling of Sporadic Task Systems
ECRTS '09 Proceedings of the 2009 21st Euromicro Conference on Real-Time Systems
Cyber-physical systems: the next computing revolution
Proceedings of the 47th Design Automation Conference
Contactless sensing of appliance state transitions through variations in electromagnetic fields
Proceedings of the 2nd ACM Workshop on Embedded Sensing Systems for Energy-Efficiency in Building
Towards dependable autonomous driving vehicles: a system-level approach
ACM SIGBED Review
Parallel scheduling for cyber-physical systems: analysis and case study on a self-driving car
Proceedings of the ACM/IEEE 4th International Conference on Cyber-Physical Systems
Sufficient real-time analysis for an engine control unit
Proceedings of the 21st International conference on Real-Time Networks and Systems
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Traditional mechanical subsystems in automobiles are being replaced by electronically controlled systems, often with no mechanical backup. This trend towards "drive-by-wire" systems is becoming increasingly popular. In these cyber-physical systems, a critical task not meeting its timing deadline can lead to a safety violation and damage to life and/or property. Classical real-time scheduling techniques such as RMS and EDF can be used to guarantee the schedulability of periodic tasks. However, certain critical tasks like the engine control task are activated by engine events such as pulses generated by sensors at the engine crankshaft. The periods of these engine tasks vary continually and even dramatically depending on the engine speed. The conventional periodic task model is inadequate for handling such tasks in cyber-physical systems due to its pessimism when combined with common schedulability analyses. In this paper, we define a new task model called Rhythmic Tasks for tasks having periods that vary due to external physical events. To the best of our knowledge, this is the first model that considers continually varying periods for fixed-priority scheduling in dynamic operating environments. We formally define the rhythmic task model and study its scheduling properties. In the context of rhythmic engine control tasks, we offer schedulability tests for determining the maximum possible utilization under the steady state, which is related to the physical engine speed. We also investigate the range of possible engine acceleration and deceleration rates. We show that excessive acceleration and deceleration can make the system unschedulable. We provide algorithms to find the appropriate ranges for acceleration and deceleration rates. We use a specific case study of engine control to illustrate our analysis.