amota.bib

@inproceedings{ANTUNES_INDIN_2007,
  author = {Antunes, A. and Pedreiras, P. and Almeida, L. and Mota, A.},
  title = {Dynamic Rate and Control Adaptation in Networked Control Systems},
  booktitle = {5th IEEE International Conference on Industrial Informatics (INDIN'2007) Proceedings},
  year = {2007},
  editor = {},
  volume = {2},
  series = {},
  pages = {841--846},
  address = {Vienna, Austria},
  month = {July},
  organization = {},
  publisher = {},
  doi = {10.1109/INDIN.2007.4384883},
  issn = {1935-4576},
  isbn = {978-1-4244-0851-1},
  keywords = {Real-Time systems, Embedded systems, distributed control system, distributed feedback control loop system, dynamic rate adaptation technique, embedded control system, networked control system, operational flexibility, sampling period},
  note = {},
  key = {},
  abstract = {Modern embedded control systems are asked to exhibit higher distribution, higher degree of integration and to support operational flexibility. Conventionally the planning of distributed control systems was done either by considering worst-case requirements, leading to expensive and inefficient designs, or by considering average requirements, potentially leading to occasional run-time overloads. The dynamic rate adaptation technique was developed to support operational flexibility and a higher degree of integration in distributed control systems. This technique adapts the communication requirements of distributed feedback control loops by increasing the sampling periods of the messages associated to the control action in order to free network bandwidth when a possible network overload condition is detected. The distributed controllers have to be able to deal with the change of the sampling period and the variable sampling to actuation delay. This work reports different control approaches used in the implementation of the dynamic rate adaptation method, namely a static version based on a set of controllers with parameters pre-computed off-line, a dynamic version where the system parameters are identified online according to the dynamic behaviour of the distributed system and a hybrid version using an adaptive controller with a set of online identifiers}
}

@inproceedings{ANTUNES_ANIPLA_2006,
  author = {Antunes, A. and Pedreiras, P. and Almeida, L. and Mota, A.},
  title = {Dynamic Rate Adaptation in Distributed Computer Control Systems},
  booktitle = {International Congress of the Italian National Association for Automation (ANIPLA'2006) Proceedings},
  year = {2006},
  editor = {},
  volume = {},
  series = {},
  pages = {},
  address = {Rome, Italy},
  month = {November},
  organization = {},
  publisher = {},
  doi = {},
  issn = {},
  isbn = {},
  keywords = {CAN, FTT-CAN, Real-Time, Embedded systems},
  note = {Best paper award; selected for journal publication},
  key = {},
  abstract = {There is currently a trend towards higher distribution in embedded control systems that leads to an increased information exchange among system nodes. Moreover, there are cases in which several subsystems exhibit varying communication requirements. Planning the whole distributed system according to worst-case requirements may lead to expensive and inefficient designs. On the other hand, considering lower requirements may lead to occasional run-time overloads. In this paper we propose a technique based on rate switching to adapt the communication requirements of distributed feedback control loops. This technique reduces the sampling rate of those loops to free network and processor bandwidth and oppose to the overload at the expense of a small degradation of the control quality. The dynamic rate adaptation is carried out using the built-in online scheduling and Quality-of-Service (QoS) management features of the FTT-CAN protocol. The paper includes the description of the approach together with a simulation using TrueTime that shows the effectiveness of the proposed technique}
}

@inproceedings{ANTUNES_ETFA_2005,
  author = {Antunes, A. and Pedreiras, P. and Mota, A.},
  title = {Adapting the sampling period of a real-time adaptive distributed controller to the bus load},
  booktitle = {10th IEEE Conference on Emerging Technologies and Factory Automation (ETFA'2005) Proceedings},
  year = {2005},
  editor = {},
  volume = {1},
  series = {},
  pages = {1084-1088},
  address = {Catania, Italy},
  month = {September},
  organization = {},
  publisher = {},
  doi = {10.1109/ETFA.2005.1612648},
  issn = {},
  isbn = {0-7803-9401-1},
  keywords = {CAN, FTT-CAN, communication infrastructure, distributed adaptive control system, field bus, message scheduling, network-induced jitter, pole-placement controller, real-time adaptive distributed controller},
  note = {},
  key = {},
  abstract = {This paper presents a new method to allow more flexibility on the scheduling of messages across a fieldbus in overload situations. The method proposes the on-line adaptation of the sampling period to the bus load, trying to keep it as low as possible during overloads. The sampling period is allowed to change inside an interval corresponding to 4 to 10 samples per rise time. To assess the solution herein presented, a distributed adaptive control system was implemented in TrueTime, using the FTT-CAN protocol, for the communication infrastructure, a pole-placement controller and a model for the identification of plant parameters that takes into account the network-induced jitter}
}