Bare-Metal Kernels for DEVS Model Execution in Embedded Systems

Abstract

With the rising popularity of embedded systems came new challenges due to evergrowing market application demands, increasing complexity and widening productivity gap. To deal with these issues, model-driven development promotes a higher level of abstraction during design and uses models as the primary artifacts that guide the product development. In fact, the fundamental principle is to construct a model of a system and then transform it into the real system. We focus on DEMES, a model-driven development methodology based on the Discrete Event System Specification (DEVS)-that defines a formal Modeling and Simulation framework for discrete event dynamic systems-, and especially the transition from simulated platform to execution platform, i.e. the embedded hardware. In this dissertation, we present bare-metal real-time executives that allow DEVS models to be executed on a target platform without the need of an operating system. This is particularly important for target platforms with limited resources. In addition to the real-time executives, we introduce a hardware abstract layer that supports several hardware peripheral libraries and fosters fast prototyping. We also illustrate the DEMES-driven development cycle with a particular case study: a line tracking robot application. Our contributions have resulted in a reduced footprint, increased performance and enhanced platform portability. I thank Dr Gabriel Wainer whose invaluable advice and ongoing support helped through my graduate studies and research. One of my objectives in graduate school was to work with and learn from some of the best in the field, and I had this privilege under his supervision. The past two years have been both a challenging and rewarding experience. I also thank the members of the Advanced Real-Time Simulation Laboratory for their help and comradeship. v

Control of a Quadcopter Application with Devs

“…-Testing: defining experimental frames can be automated. In order to implement a quadcopter controller using the DEMES methodology, we have used a kernel (Embedded CDBoost) that allows the users to run their DEVS models directly on bare-metal without the need of an operating system (Niyonkuru 2015) and a DEVS simulator (CDBoost)…”

“…Moreover, these approaches do not cover hardware-software co-design, and the final design is hard to verify against the initial specification. Therefore, the development process usually involves long testing phases, error-prone products, and increased time to market (Niyonkuru 2015).…”

“…Moreover, M&S techniques in general, and DEMES in particular, allow building testing scenarios easily and simulate them, without the need of the hardware and/or the need of the real environment. Niyonkuru and Wainer developed two kernels based on DEMES: Embedded CD++ (E-CD++) and Embedded CDBoost (E-CDBoost) (Niyonkuru and Wainer 2015b;Niyonkuru 2015;Niyonkuru and Wainer 2015a) that allow users to run models directly on bare-metal without the need of an operating system. Both kernels differ in the communication mechanism used between model execution engines.…”

“…The objective of this paper is to show how to use DEMES to develop a controller for a quadcopter. We use E-CDBoost because it has shown better overhead performance than E-CD++ (Niyonkuru 2015). To achieve this objective, we will use, as case study, the development of a PID controller for Crazyflie2.0 (Bitcraze Wiki, Bitcraze.io Crazyflie 2.0), a small quadcopter mainly used for research, education and development.…”