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In this contribution, we suggest two proposals to achieve fast, real-time lane-keeping control for Autonomous Ground Vehicles (AGVs). The goal of lane-keeping is to orient and keep the vehicle within a given reference path using the front wheel steering angle as the control action for a specific longitudinal velocity. While nonlinear models can describe the lateral dynamics of the vehicle in an accurate manner, they might lead to difficulties when computing some control laws such as Model Predictive Control (MPC) in real time. Therefore, our first proposal is to use a Linear Parameter Varying (LPV) model to describe the AGV's lateral dynamics, as a trade-off between computational complexity and model accuracy. Additionally, AGV sensors typically work at different measurement acquisition frequencies so that Kalman Filters (KFs) are usually needed for sensor fusion. Our second proposal is to use a Dual-Rate Extended Kalman Filter (DREFKF) to alleviate the cost of updating the internal state of the filter. To check the validity of our proposals, an LPV model-based control strategy is compared in simulations over a circuit path to another reduced computational complexity control strategy, the Inverse Kinematic Bicycle model (IKIBI), in the presence of process and measurement Gaussian noise. The LPV-MPC controller is shown to provide a more accurate lane-keeping behavior than an IKIBI control strategy. Finally, it is seen that Dual-Rate Extended Kalman Filters (DREKFs) constitute an interesting tool for providing fast vehicle state estimation in an AGV lane-keeping application.

El ámbito de actuación se encuentra en el municipio de Soria, dentro de su casco histórico. Lo constituye la manzana, limitada por las calles Sorovega, Betetas, Teatro y la propia Plaza Mayor, donde se encuentran el edificio de la Audiencia, la Casa Consistorial y la Torre de Doña Urraca (antiguo Palacio de los Beteta), por lo que se sitúa en uno de los lugares más representativos de la Ciudad. Colindantes al ámbito de actuación encontramos dos elementos históricos de Soria: Palacio de los Beteta o de Sorovega y el Palacio de la Audiencia. Del edificio del XVI, también conocido como Palacio de Sorovega, sólo queda un torreón (Torre de Doña Urraca), que debió tener alrededor un perímetro amurallado con muros de piedra almenada. En la fachada, con tres de los cuatro pisos que tuvo en origen, se abre bajo una decoración de candelabros un balcón adintelado. La sencilla puerta en arco da acceso al patio que tuvo el palacio. En el interior algunas dependencias cuentan con artesonado de madera. El Palacio de la Audiencia es una obra neoclásica del siglo XVIII, según planos del arquitecto José Oñaederra, en un primer momento, y de Domingo Ondátegui, más tarde, se trata de un edificio de planta rectangular, con un pórtico de arcos de medio punto sobre pilares en la planta baja y un piso noble con balcón corrido y cuatro vanos adintelados coronados por frontones rectilíneos. Fue rehabilitado en 1986 de mano de varios arquitectos: Mariano Magister, Ricardo Martínez y Javier Maroto. El edificio tiene tres plantas, dos salas de exposiciones y dos salas de conferencias, además del propio teatro. El proyecto surge de la necesidad de reactivar la ciudad de Soria que actualmente está inmersa en una lucha contra la despoblación en la que año tras año su población joven va en decadencia debido a la falta de oportunidades y de infraestructuras , mientras que su número de habitantes no sufre grandes caídas gracias a la inmigración , un dato que si es preocupante es que la población sori

© 2019 IEEE. Personal use of this material is permitted. Permissíon from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertisíng or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.", [EN] In this paper, periodic event-triggered sampling and dual-rate control techniques are integrated in a wireless networked control system (WNCS), where time-varying network-induced delays and packet disorder are present. Compared to the conventional time-triggered sampling paradigm, the control solution is able to considerably reduce network utilization (number of transmissions), while retaining a satisfactory control performance. Stability for the proposed WNCS is ensured using linear matrix inequalities. Simulation results show the main benefits of the control approach, which are experimentally validated by means of an unmanned-aerial-vehicle-based test-bed platform.

[EN] In this paper, a novel control scheme for systems with input and output time-varying delays is provided in discrete-time domain. The control strategy combines predictor-like techniques with a delay-dependent gain-scheduled extended state observer. The main goal is twofold: (i) to minimize the negative effect of time-varying delays in the closed-loop performance and, (ii) to actively compensate the effect of mismatched disturbances in the controlled output. Moreover, a sufficient condition based on Linear Matrix Inequalities (LMI) is provided to obtain the maximum delay interval that ensures the stability of the closed-loop system. Finally, the achieved benefits of the proposal are shown by simulation in open-loop unstable plants, and experimentally validated in a test-bed quadrotor platform. (C) 2018 ISA. Published by Elsevier Ltd. All rights reserved.

[EN] In this paper, a novel delay-independent control structure for a networked control system (NCS) is proposed, where packet-based control strategies with predictor-based and dual-rate control techniques are integrated. The control solution is able to cope with some networked communication problems such as time-varying delays, packet dropouts and packet disorder. In addition, the proposed approach enables to reduce network load, and usage of connected devices, while maintaining a satisfactory control performance. As a delay-independent control solution, no network-induced delay measurement is needed for controller implementation. In addition, the control scheme is applicable to open-loop unstable plants. Control system stability is ensured in terms of linear matrix inequalities (LMIs). Simulation results show the main benefits of the control approach, which are experimentally validated by means of a Cartesian-robot-based test-bed platform. (C) 2019 Elsevier Inc. All rights reserved.

[EN] This paper proposes a systematic non-uniform multi-rate estimation and control framework for a periodic event-triggered system which is subject to external disturbance and sensor noise. When the disturbance dynamic model is available, and in order to efficiently estimate the state variable and disturbance from non-uniform slow-rate measurements, a time-varying Kalman filter is designed. When the disturbance dynamic model is not available, a disturbance observer is proposed as an alternative approach. Both the Kalman filter and the disturbance observer are proposed in a non-uniform multi-rate format. Such disturbance estimation enables faster controller updating in spite of slower measurement. Interlacing techniques are used in the control system to uniformly distribute the computational load at each fast sampling instance. Compared to the conventional time-triggered sampling paradigm, the control solution is able to reduce the resource utilization, while maintaining a satisfactory control performance. The proposed control solution will reduce the number of transmissions among devices, which enhances the energy and computational efficiency. Simulation results are provided to validate the effectiveness and benefits of the proposed control algorithms. (C) 2018 Elsevier Inc. All rights reserved.

[EN] This paper introduces a packet-based dual-rate control strategy to face time-varying network-induced delays, packet dropouts and packet disorder in a Networked Control System. Slow-rate sensing enables to achieve energy saving and to avoid packet disorder. Fast-rate actuation makes reaching the desired control performance possible. The dual-rate PID controller is split into two parts: a slow-rate PI controller located at the remote side (with no permanent communication to the plant) and a fast-rate PD controller located at the local side. The remote side also includes a prediction stage in order to generate the packet of future, estimated slow-rate control actions. These actions are sent to the local side and converted to fast-rate ones to be used when a packet does not arrive at this side due to the network-induced delay or due to occurring dropouts. The proposed control solution is able to approximately reach the nominal (no-delay, no-dropout) performance despite the existence of time-varying delays and packet dropouts. Control system stability is ensured in terms of probabilistic Linear Matrix Inequalities (LMIs). Via real-time control for a Cartesian robot, results clearly reveal the superiority of the control solution compared to a previous proposal by authors. (C) 2018 ISA. Published by Elsevier Ltd. All rights reserved.