Home page of Sylvain DURAND CHAMONTIN
Interests of research

1

Event-based control of cyber-physical systems

Cyber-physical systems:A cyber-physical system is an integration of computing devices with physical processes. In practice, embedded computers and networks monitor and control physical processes (usually with feedback loops) which, in return, affect computations and communications. The intersection between physical and information-driven (cyber) functions hence represents a challenge and results in innovation. The use of digital platforms also emerges as an obvious trend to save space, weight and energy. However, their implementation can result in additional challenges, like determining how frequently the control signal needs to be updated and applied such that the stability properties are still guaranteed.

Reduction of the resource utilization:The consistently-used periodic fashion consists in sampling the system uniformly in time with a constant sampling period. Although such a periodicity simplifies the design and analysis, it results in a conservative usage of resources since the control law is computed and updated at the same rate regardless whether is really required or not. Nevertheless, alternative works addressed more recently resource-aware implementations of the control law using event-based sampling, where the control law is event triggered. The idea is to soften the computational load in reducing the number of sampling instants (and consequently the CPU utilization and/or communication bandwidth) for the same final performance. This is interesting for embedded systems with resource constraints.

Event-based control for embedded systems:Although the event-triggered control paradigm is well-motivated, only few works report theoretical results in the literature. I am interested in developing new event-based techniques for the stabilization of (linear and nonlinear) embedded cyber-physical systems. I proposed different approaches (PID, LQR, universal formula, etc...) for linear and nonlinear systems, and tested them on several systems (motor, inverted pendulum, small car, mini helicopters, gyroscope, etc...).

These works were mainly done during my research positions at GIPSA-lab and UMI LAFMIA, in collaboration with the BUAP university.

Further results

2

Control of embedded electronic devices in advanced technology

Reduction of the energy consumption:I am interested in controlling the energy-performance tradeoff in Many-Processor Systems on Chip (MPSoC). In particular, I proposed a fast predictive control strategy which minimizes the energy consumption while ensuring good computational performance of the system (all the tasks to treat are correctly performed before their deadline) using Dynamic Voltage and Frequency Scaling (DVFS) techniques. The idea is to speed up the execution of a task under the penalizing high supply voltage level (and its associated frequency) during a certain time, and then finish the task under the low voltage and a slower frequency. The proposed strategy is highly robust to tackle variability which is a real problem in integrated systems in (nanometric) advanced technologies (because the performance after fabrication is not fully predictable in such a technological scale).

These works were mainly done in the Minalogic ARAVIS project context (which partners are STMicroelectronics, CEA-Leti, TIMA, GIPSA-lab, INRIA Grenoble Rhône-Alpes).

Further results

Limitation of the temperature:I am also interested in the thermal aspect in MPSoC. I notably extended the previous work to a chopped version, where several switches of the voltage and frequency levels performed during the execution of a given task (while still keeping the same ratio as before) allow to limit the final attained temperature and decrease the appearance of hot spots.

This work was mainly done in the CRI PILSI (CEA-Leti, INRIA Grenoble Rhône-Alpes) context.

Further results

3

Robotics systems

Control of robotics systems:I am interested in developing and controlling complex (nonlinear, unstable, under-actuated, etc...) dynamical robotics systems.

Further results

These works were mainly done during my research positions at GIPSA-lab and ISM, in the context of the French national program of experimental platforms in robotics, i.e. Robotex.

4

Networked systems (with communication delays)

Networked Control Systems:With the development of embedded, miniaturized and interconnected systems, there is a growing interest in Networked Control Systems (NCSs) where the control loop is closed over a communication link. A network has several advantages, but it also has a considerable impact on the performance, notably because of communication delays and packet losses which avoid real-time control constraints to be meet and can even cause the instability of the control loop.

Event-based control for networked systems:I am interested in developing control strategies for NCS when taking in consideration the delays. More particularly, I proposed event-based control strategies for stabilization of linear and nonlinear time-delay systems.

These works were mainly done during my research positions at GIPSA-lab and UMI LAFMIA.

Further results

5

Autonomic computing systems

Control of autonomic computing systems:I am interested in controlling computing systems, where sensors, actuators, and controllers are software. I notably worked on the modelling and control of such systems in order to make them autonomic, i.e. more adaptative and reconfigurable.

Further results

6

Observer for position estimation

State observer:An observer is required when some (state) variables of a system to control are not accessible from the available measurements. I am mainly interested in the estimation of the attitude and position for autonomous (aerial and terrestrial) vehicles.

This work was mainly done in collaboration with the BUAP university.

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