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International audience; We further develop a novel control paradigm encoding the core behavior of a reset control system within a continuoustime feedback, described by a differential inclusion. A tuning knob allows adjusting how close the continuous-time feedback resembles the behavior of the underlying reset controller. The Lyapunov conditions that we derive naturally lead to a sum-of-squares formulation allowing for the design of max-of-quadratics Lyapunov certificates certified by polynomial multipliers. A few application examples confirm the practical effectiveness of the proposed solutions.

The Plasma Control System (PCS) of the Frascati Tokamak Upgrade (FTU) is not equipped with any runaway electron (RE) beam control or suppression tool. In this paper we propose an upgraded PCS including an architecture for the control of disruption-generated REs that, making use of filtering techniques to estimate the onsets of the current quench (CQ) and of the RE beam current plateau, provides a controlled plasma current shut-down and a simultaneous RE position control. The control strategy is based on a nonlinear technique, called Input Allocation, that allows to re-configure the current in the poloidal field (PF) coils and improve the PCS responsiveness needed for RE position control. Preliminary results on the implementation of the Input Allocation and an experimental proposal to test the control scheme architecture are discussed. © 2013 Elsevier B.V. All rights reserved.

The Current Limit Avoidance System (CLA) has been recently deployed at the JET tokamak to avoid current saturations in the poloidal field (PF) coils when the eXtreme Shape Controller is used to control the plasma shape. In order to cope with the current saturation limits, the CLA exploits the redundancy of the PF coils system to automatically obtain almost the same plasma shape using a different combination of currents in the PF coils. In the presence of disturbances it tries to avoid the current saturations by relaxing the constraints on the plasma shape control. The CLA system has been successfully implemented on the JET tokamak and fully commissioned in 2011. This paper presents the first experimental results achieved in 2011–2012 during the restart and the ITER-like wall campaigns at JET.

A current limit avoidance (CLA) system has been proposed to avoid current saturation in the poloidal field (PF) coils of the Joint European Torus tokamak when the eXtreme Shape Controller is used to control the plasma shape. CLA uses the redundancy of the PF coil system to automatically obtain almost the same plasma shape with a different combination of control currents. This paper describes the set of graphic tools that has been recently developed to aid the design of the CLA parameters by nonexpert users.

In this paper, we revisit the dynamic allocation scheme for input redundant plants proposed in Zaccarian (2009). within a set-point regulation setting and propose generalizations that apply to cases where the plant under consideration is not input redundant but the control specifications allow us to modify the set-point regulation within certain bounds. In this case, the input allocator is extended to the nonredundant case by allowing it to improve the input allocation selection at the price of some output regulation error. We also establish here desirable convergence properties of the allocator, which were only addressed for the linear case in Zaccarian (2009). In particular, we design the allocator dynamics as the gradient of a cost function and establish its convergence to the minimum of the cost function under some mild conditions. The allocation scheme is applied to the JET tokamak shape controller by illustrating its capabilities to enforce coil currents selections that tend to move away from the saturation limits within the allowable degrees of freedom.

In this paper we propose a solution to the input saturation avoidance problem in the JET tokamak shape control by illustrating its capabilities to enforce coil currents selections that tend to move away from the saturation limits within the allowable degrees of freedom. The proposed solution revisits the dynamic allocation scheme first proposed in [10] for input redundant plants and generalized in [6] and [9] for not input redundant ones. In particular we propose a different scheme for the input allocation, more suitable within a set-point regulation setting, and prove its convergence properties. We also present simulation results to assess the steady-state and transient performances obtained with the novel scheme, as compared to the previous approaches.

In this paper we revisit the dynamic allocation scheme for input redundant plants proposed in [12] within a set-point regulation setting and propose generalizations that apply to cases where the plant under consideration is not input redundant but the control specifications allow to modify the set-point regulation within certain bounds. In this case, the input allocator is extended to the nonredundant case by allowing it to improve the input allocation selection at the price of some output regulation error. Similar to [12], the allocator behaves according to some dynamics that converges to the minimum of a certain cost function. The allocation scheme is applied to the JET tokamak shape controller by illustrating its capabilities to enforce coil currents selections that tend to move away from the saturation limits within the allowable degrees of freedom. The allocator behavior is illustrated by simulation on the JET tokamak both in off-line operation (in open loop during the pulse planning phase) and in on-line operation (in closed loop during the pulse).

The chapter is devoted to the presentation of a novel fault detection and control reconfiguration problem. An implicit fault tolerant control scheme is presented and specialized for an n-degree-of-freedom fully actuated mechanical manipulator subject to sinusoidal torque disturbances acting on the joints. The solution of the usual tracking main problem is "augmented" via an internal model unit designed to compensate the unknown spurious torque armonics. Testing the state of such unit allows fault detection and isolation. Simulations are provided.

In multi-retailer inventory control the possibility of sharing setup costs motivates communication and coordination among the retailers. We solve the problem of finding suboptimal distributed reordering policies that minimize setup, ordering, storage, and shortage costs incurred by the retailers over a finite horizon. Neuro-dynamic programming (NDP) reduces the computational complexity of the solution algorithm from exponential to polynomial on the number of retailers.