Olivier Sename

Towards global chassis control by integrating the brake and suspension systems

Abstract A control structure that integrates active suspensions and an active brake is proposed to improve the safety of vehicles. The design is based on an ℋ∞ control synthesis extended to LPV systems and uses a parameter dependent Lyapunov function. In an emergency, such as an imminent rollover, the safety requirement overwrites the passenger comfort demand by tuning the performance weighting functions associated with the suspension systems. If the emergency persists active braking is applied to reduce the effects of the lateral load transfers and thus the rollover risk. The solution is facilitated by using the actual values of the so-called normalized lateral load transfer as a scheduling variable of the integrated control design. The applicability of the method is demonstrated through a complex simulation example containing vehicle maneuvers.

Feedback scheduling for real-time control of systems with communication delays

This work is devoted to integrated control-scheduling in the case of real-time control of systems with communications delays, i.e. network induced delay and input output latency. Feedback control of computing resources is tackled to deal with CPU resource variations and unpredictable workload. Thus, two new control schemes are provided for feedback scheduling of single and multi control task systems. Moreover, the system control design takes into account the unknown delays due to the temporal uncertainties that are unavoidable in real-time control. A new method of state feedback control design for discrete time-delay systems is presented in a LMI formulation. Two illustrative examples show the interest of the proposed approach.

H ∞ -Based impedance control of teleoperation systems with time delay 1

Abstract Impedance control is used to adjust the dynamic relationship between the position of a manipulator and the applied forces when it interacts with the environment. In bilateral teleoperation systems, communication time delay may destabilize the closed-loop system and certainly degrade the operator’s intuition and performance. In this paper, a new scheme for impedance control of bilateral teleoperation systems in the presence of communication time delay is proposed. Local controller for master manipulator is firstly designed in order to get a specified master impedance. Then, a global controller is designed based on H ∞ framework such that the global system, including communication time delay, is stable and the desired impedance characteristic of the slave manipulator is achieved asymptotically.

A LPV approach to control and real-time scheduling codesign: Application to a robot-arm control

This paper deals with real-time control under computational constraints. A robust control approach to control/real-time scheduling co-design is proposed using the H¿ framework for linear parameter varying (LPV) polytopic systems. The originality consists in a new resource sharing between control tasks according to the controlled plant performances. Here the varying parameters are images of the control performance w.r.t. the sampling frequencies. Then a LPV based feedback scheduler is designed to adapt the control tasks periods according to the plant behavior and to the availability of computing resources. The approach is illustrated with a robot-arm controller design, whose feasibility is assessed in simulation.