Deterministic control communication is a backbone of many novel complex (robotic) engineering systems, e.g. HUBO uses CAN. The aim of this research , is to develop an approach for cheap and deterministic control communication using Ethernet. The objectives require a reliable data-transfer service between the various units for sensing and actuation. The key discriminator to assess reliability is determinism, (e.g. causality and well defined order of communication events in time and transaction). The strategy to support this at the network level, include investigations of approaches based on time-triggering, arbitration and guarantees of latency. A half-duplex Ethernet network populated with a small/medium number of Media Access Controllers (MACs) is used for timed real-time communication. A time-triggered approach is used, i.e. a synchronization signal triggers the sending of data from each Ethernet data transmitting unit. Moreover, data packets are sent at well defined times after each trigger instance to reduce collisions. Collisions mainly occur due to jitter of the transmission system, so that arbitration (similar to CANopen) is necessary. A Linear Backoff scheme is used in comparison to the Binary Exponential Backoff scheme. Matlab and Field Programmable Gate Array (FPGA) technology, i.e. Xilinx XC3S500E from the Spartan-3E family, are used to simulate and implement the practical test of the Ethernet communication strategy. Practical comparisons to a time division multiple access scheme for the Matlab simulation environment and the FPGA based experimental setup are carried out. Furthermore, a theoretical analysis of the communication approach is provided. In particular the advantage of . the communication unit specific minimal backoff time using a Nlarkov model is shown.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:682362 |
| Date | January 2015 |
| Creators | Ishak, Mohamad Khairi |
| Publisher | University of Bristol |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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