1,721,104 research outputs found
Communication Demand Minimization for Perturbed Networked Control Systems with Coupled Constraints
No full textCommunication scheduling is needed when control loops of several safety-critical systems are closed through a shared communication medium. To enable schedulability, control for each system is designed primarily to minimize its communication demand. In this paper, we study communication demand minimization for a class of perturbed multi-agent networked control systems with a shared communication medium and subject to input and coupled state constraints. First, a framework to design communication schedule and control is recalled such that state and input constraints are satisfied under no coupling assumption. Then, a heuristic method is proposed to decouple state constraints such that the overall communication demand of the systems is minimized. Effectiveness of the proposed results are illustrated through a numerical example
Optimal control of networked and transportation systems
Full text linkThis special issue is concerned with the optimal control of systems over networks and the use in transport system applications
Optimal Coordination of Automated Vehicles at Intersections: Theory and Experiments
Full text linkWith the introduction of Cooperative Automated Vehicles, traffic lights can be replaced by coordination algorithms. In this paper, we present a bi-level, model predictive controller for coordination of automated vehicles at intersection. The bi- level controller consists of a coordination level, where intersection occupancy timeslots are allocated, and vehicle-level controllers, where the control commands for the vehicles are computed. We establish persistent feasibility and stability of the bi-level controller under some mild assumptions, and derive conditions under which closed-loop collision avoidance can be ensured with bounded position uncertainty. We thereafter detail an implemen- tation of the coordination controller on a three-vehicle test bed, where the intersection-level optimization problem is solved using a distributed Sequential Quadratic Programming (SQP) method. We present and discuss results from an extensive experimental campaign where the proposed controller was validated. The experimental results indicate the practical applicability of the proposed controller, and validates that safety can be ensured for large positioning uncertainties
Optimal Control Design for Perturbed Constrained Networked Control Systems
Full text linkThis letter focuses on an optimal control design problem for a class of perturbed networked control systems where a number of systems, subject to state and input constraints, share a communication network with limited bandwidth. We first formulate an optimal control design problem with a constant feedback gain in order to minimize the communication demand for each system while guaranteeing satisfaction of state and input constraints; we show that this optimization problem is very hard to solve. Then, we formulate the same optimal control design problem with a non-constant feedback gain; we argue that this problem is less difficult and results in a lower, or equal, communication demand in comparison to the design with the constant feedback gain. We illustrate and compare these optimal control designs by a simple example
On the thermal welding of paper-based polylaminate packages: Modelling, numerical implementation and sensitivity analysis
No full textThis work presents a numerical model for the simulation of pack- age sealing in industrial machines for beverage packaging. The simulations are aimed at the prediction of the temperature field in all the layers of the polylaminate material composing the package. The package sealing is in fact carried out by means of thermal welding. Thus, accurate predictions of the temperatures following the package heating via hot air jet and right before the folding flaps are pressed together is paramount to in turn predict sealing success. The heat equation is solved in the package volume by means of a plate FEM formulation in which arbitrary order Lagrangian shape function are used for both the longitudinal and the normal discretization. The resulting semi-discretized equations are time advanced by means of an Implicit Euler scheme with constant time step. The solution of the system is complemented by forward sensitivity computation to obtain, at each time step, quantitative assessment of the effect of process parameters variations on the temperature output. The numerical results are compared to experimental measurements so as to validate the developed simulation tool. The results obtained suggest that the solver is able to reproduce with satisfactory accuracy the experimen- tal temperature field evolution in the portion of the package interested by the thermal welding
Robust Control Invariance for Networked Control Systems with Output Feedback
No full textThis paper focuses on robust output feedback design for multi-agent networked control systems with a shared communication medium, where each system is subject to state and input constraints. We first compute the communication demand for each system given constant observer and controller gains; we argue that minimization of the communication demand with respect to the control or observer gains is very hard. Then, given a constant observer gain, we compute the minimum communication demand for each system and a corresponding control policy using model predictive control; we argue that the second approach is less difficult to solve and results in a communication demand which is no larger than for a linear controller. We illustrate and compare these design methods by a numerical example
Experimental Validation of Distributed Optimal Vehicle Coordination
No full textIn this paper we solve the problem of coordinating autonomous vehicles approaching an intersection in experi- ments. We cast the problem in the distributed optimisation framework and use the algorithm proposed in [10], [14] to solve it in real time. We compare two variants of the algorithm in simulations and test our algorithm in experiments using real cars on a test track. The experimental results demonstrate the applicability and real-time feasibility of the algorithm and show that the underlying assumptions are justified
Real-Time Constrained Trajectory Planning and Vehicle Control for Proactive Autonomous Driving with Road Users
Full text linkFor motion planning and control of autonomous vehicles to be proactive and safe, pedestrians\u27 and other road users\u27 motions must be considered. In this paper, we present a vehicle motion planning and control framework, based on Model Predictive Control, accounting for moving obstacles. Measured pedestrian states are fed into a prediction layer which translates each pedestrians\u27 predicted motion into constraints for the MPC problem.Simulations and experimental validation were performed with simulated crossing pedestrians to show the performance of the framework. Experimental results show that the controller is stable even under significant input delays, while still maintaining very low computational times. In addition, real pedestrian data was used to further validate the developed framework in simulations
An Asynchronous Algorithm for Optimal Vehicle Coordination at Traffic Intersections
No full textIn this paper we propose an algorithm for vehicle coordination at intersections in order to avoid collisions within the intersection area while optimising an objective given as the sum of individual costs associated with each agent. Extending the results presented in Hult et al. (2016), we develop an algorithm with asynchronous sensitivity updates in order to reduce the time spent in communication. We select which sensitivities to update in order to minimise an upper bound on the contraction of the inexact Newton iterates and introduce a projection of the inexact Newton steps in order to ensure feasibility of the local problems. We prove convergence of our algorithm and test it on a numerical example in order to validate its effectiveness
Optimal Scheduling of Downlink Communication for a Multi-Agent System with a Central Observation Post
No full textIn this paper, we consider a set of agents, which may receive an observation of their state by a central observa- tion post via a shared wireless network. The aim of this work is to design a scheduling mechanism for the central observation post to decide how to allocate the available communication resources. The problem is tackled in two phases: (i) first, the local controllers are designed so as to stabilise the subsystems for the case of perfect communication; (ii) second, the com- munication schedule is decided with the aim of maximising the stability of the subsystems. To this end, we formulate an optimisation problem which explicitly minimises the Lyapunov function increase due to communication limitations. We show how the proposed optimisation can be expressed in terms of Value of Information (VoI), we prove Lyapunov stability in probability and we test our approach in simulations
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