Jonathan Dumon

Experimental study of the D-OSKIL mechanism for controlling the stick-slip oscillations in a drilling laboratory testbed

The presence of harmful stick-slip oscillations in oil well drillstrings has attracted the attention of the control community in recent years. The control law named D-OSKIL mechanism which uses the weight on the bit (WoB) force as an additional control variable to extinguish limit cycles has been investigated [1]. This paper reports experimental implementation of such a mechanism, in a laboratory testbed. We also provide details of the experimental process and the obtained drilling performance. Results show that the stick-slip oscillations can be effectively suppressed by this mechanism.

Event-Based Control for Embedded and Networked System: Application to a Mini Quadrotor Helicopter using Motion Capture

Although periodicity simplifies design and analysis in control theory, it is no more adapted for embedded and networked cyber-physical systems because it results in a conservative usage of resources. Indeed, the control signal is computed and updated at the same rate regardless whether is really required or not, and is periodically sent on the communication link. On the other hand, event-driven sampling calls for resources whenever they are indeed necessary. An event-based controller is proposed in this paper as a solution to reduce the updates from the controller to the plant. An event-based corrector is also added to reduce the communications from the plant to the controller. The approach is tested for controlling the position of a real-time mini quadrotor helicopter using a motion capture system with deported controller. A reduction of the computing/communication resources utilization is highly demonstrated for similar final performance.

Adaptive observer design under low data rate transmission with applications to oil well drill-string

In oil well drilling operations, one of the important problem to deal with is represented by the necessity of suppressing harmful stick-slip oscillations. A control law named D-OSKIL mechanism uses the weight-on-the-bit force as a control variable to extinguish limit cycles. It uses the value of the bit angular velocity that is found through an unknown parameter observer by means of the measure of the table rotary angular speed. To improve this former estimation, we add the measurement of the angular velocity of the bit that, due to the technological constraints, arrives delayed. This new design leads us to the analysis of a time-varying delay system.

A supervisory control policy over an acoustic communication network

This paper presents a supervisory multi-agent control policy over an acoustic communication network subject to imperfections (packet dropout and transmission delay) for localisation of an underwater flow source (e.g., source of chemical pollution, fresh water, etc.) with an unknown location at the bottom of the ocean. A two-loop control policy combined with a coding strategy for reliable communication is presented to perform the above task. A simulator is developed and used to evaluate the trade-offs between quality of communication, transmission delay and control for a fleet of autonomous underwater vehicles supervised over a noisy acoustic communication network by an autonomous surface vessel. It is illustrated that without compensation of the effects of severe random packet dropout, localisation of an unknown underwater flow source is not possible for the condition simulated just by implementing a two-loop control policy. But a two-loop control policy combined with a strategy for reliable communication locates the unknown location of flow source.

Energy production control of an experimental kite system in presence of wind gusts

The growing need of energy, global warming and recent nuclear power plant accidents have shown that renewable energies need to be developed for tomorrows world. Wind energy is generally harvested using wind turbines. Unfortunately, these systems have some drawbacks such as their cost, and the amount of steel and concrete used for construction. As their size grows, their complexity increases exponentially. This paper studies an alternative solution for the production of wind energy, using a kites traction force. The aim of this paper is to control the amount of energy produced by the kite, and to be able to fly it safely in the presence of strong wind gusts. Our theoretical work has been implemented in a scale model flying autonomously in a wind tunnel. The proposed control strategy has led to control the system output power with an accuracy greater than 95%, with unknown wind speeds varying from 7.5 to 9 m/s.

Nonlinear control of a nano-hexacopter carrying a manipulator arm

This paper proposes a simple solution for stabilization of a nano-hexacopter carrying a manipulator arm in order to increase the type of missions achievable by these types of systems. The manipulator arm is attached to the lower part of the hexacopter. The motion of the arm induces a change of the center of mass of the whole body, which induces torques which can produce the loss of stability. The present work deals with the stabilization of the whole system - that is hexacopter and arm - by means of a set of nonlinear control laws. First, an attitude control, stabilizes the hexacopter to a desired attitude taking into account the movement of the arm. Then, a suitable virtual control and the translational dynamics allow the formulation of a nonlinear controller, which drives the aerial vehicle to a desired position. Both controls consist in saturation functions. Experimental results validate the proposed control strategy and compares the results when the motion of the arm is taken into account or not.

Velocity control of mini-UAV using a helmet system

The usage of a helmet to command a mini-unmanned aerial vehicle (mini-UAV), is a telepresence system that connects the operator to the vehicle. This paper proposes a system which remotely allows the connection of a pilots head motion and the 3D movements of a mini-UAVs. Two velocity control algorithms have been tested in order to manipulate the system. Results demonstrate that these movements can be used as reference inputs of the controller of the mini-UAV.

Reverse pumping: Theory and experimental validation on a multi-kites system

Most kite wind power systems have a great drawback that wind turbines do not have: they cannot stay in the air if the wind is not strong enough, [7-16]. As a consequence, most of the kite systems need to land when there is no wind, and to take-off once the wind is strong enough. These maneuvers are quite risky because generally the wind gets weak and turbulent close to the grounds surface. Moreover, as the wind can be strong enough at high altitude and weak close to the ground, it might lead to losses in energy production. From a material point of view, “classic” landings and takeoffs need a landing zone, ground handling or infrastructure (such as pylons) that reduces the advantages of kite systems. Some ideas, such as embedded motors or helium balloons, might solve this problem, but they have their own drawbacks such as the weight of the motor and its battery, the necessity of a conductive cable or the need to refill the balloons. The following paper studies a solution called “reverse pumping”. It basically consists of providing kinetic energy to the kite by pulling the kite with a rope. This kinetic energy is then transformed into potential energy by gaining altitude. This technique allows to keep the kite airborne in total absence of wind. This paper will study the reverse pumping principle, the constrains on the aerodynamical model, flight simulations and will present the experimental setup used to validate the theoretical study.

Control of a Magnus Effect-Based Airborne Wind Energy System

This chapter studies the control of an airborne wind energy system that is operated in pumping cycles and uses a rotating cylinder to provide aerodynamic lift with the Magnus effect. The proposed control strategy aims at stabilizing the output power production which can be used for off-grid applications, for example. In a first case study, the wind tunnel setup of a small-scale system is investigated experimentally and by means of numerical simulation. The proposed controller works well to effectively manage the tether length. However, a comparison of the results demonstrates the penalizing effects of wind turbulence with a factor of three difference in power production. In a second case study, the control strategy is used for the numerical simulation of a medium scale prototype with a potential power rating of 50 kW. The results show that the control strategy is very effective to track the desired power production even in the presence of wind velocity fluctuations. In a third case study, the scalability of the system is evaluated by applying the control scheme to the numerical simulation of a MW scale platform. The results show that the system with a span equal to the diameter of a conventional wind turbine can generate an equivalent amount of power.

Control of an airborne wind energy system with a Magnus effect

The control of an airborne wind energy system with a Magnus effect device has been studied. The proposed strategy aims to control the amount of the output energy produced for a given cycle. The control scheme has been applied numerically and experimentally on a small scale indoor setup of Gipsa-lab, and validated numerically for Omnideas experimental platform. Results have shown the good performance of the proposed control strategy.