A general framework for the deterministic medium access on the Controller Area Network

Akpınar, Murat
This thesis proposes a general framework CANDS (Controller Area Network with Determinism and Synchronization support) for in-vehicle communication on CAN. CANDS features a hierarchy of novel clock synchronization (CS) algorithms with different levels of clock accuracy and implementation complexity. Moreover, CANDS realizes our original idea of weak time division multiple access (WTDMA) for deterministic bus access, while being fully compatible with the standard CAN protocol and its recent extensions. CS methods within CANDS apply offset and drift correction. While offset correction is performed based on timestamps in periodic reference messages (RMs), drift correction is realized based on (1) the re-synchronization mechanism of the CAN bit timing; (2) drift estimates computed from periodic timestamps with RMs and (3) drift estimates determined in a discrete-time feedback control loop. Since accurate timestamps are essential for the CS performance, the thesis further develops a new timestamping (TS) method, which reduces the effect of uncertainties that are caused by the CAN bit timing, oscillator drifts and different cable lengths. Overall, clock accuracies below 100ns are achieved in hardware experiments with our TS method and CS algorithms. Benefiting from the achieved clock accuracy levels, the thesis next introduces WTDMA as a new method for slotted medium access on CAN together with novel message scheduling algorithms for the assignment of time slots in WTDMA. WTDMA is realized in software and a certain degree of interference between adjacent time slots is tolerated with the usage of Carrier Sense Multiple Access/Collision Resolution (CSMA/CR) and the non-preemptive message transmission on CAN. Sufficient conditions for the correct operation of WTDMA are derived and its practicability is validated with comprehensive hardware experiments. Specifically, bus loads above 90% and deterministic message latencies in the order of hundreds of microseconds are achieved.


An approximation for kanban controlled assembly systems
TOPAN, Engin; Avşar, Zeynep Müge (Springer Science and Business Media LLC, 2011-01-01)
An approximation is proposed to evaluate the steady-state performance of kanban controlled two-stage assembly systems. The development of the approximation is as follows. The considered continuous-time Markov chain is aggregated keeping the model exact, and this aggregate model is approximated replacing some state-dependent transition rates with constant rates. The approximate aggregate model is, then, decomposed into submodels and a product-form steady-state distribution is obtained for each submodel. Fina...
A cross-layer protocol for wireless sensor networks
Akyildiz, Ian F.; Vuran, Mehmet C.; Akan, Ozgur B. (2006-03-24)
Severe energy constraints of battery-powered sensor nodes necessitate energy-efficient communication protocols in order to fulfill application objectives of wireless sensor networks (WSN). However, the vast majority of the existing solutions are based on classical layered protocols approach. It is much more resource-efficient to have a unified scheme which melts common protocol layer functionalities into a cross-layer module for resource-constrained sensor nodes. To the best of our knowledge, to date, there...
A Control System Architecture for Control of Non-Affine in Control, Open-Loop Unstable Underactuated Systems
Marangoz, Alp; Kutay, Ali Türker (2017-07-25)
In this paper, a control system architecture for control of non-affine in control, open-loop unstable underactuated system is discussed. Passivization of the unactuated (internal) system dynamics achieved through perturbation of trajectories of the actuated states, which are calculated through adaptive dynamic inversion technique, based on Tikhonov's theorem. Performance of the controller is shown through simulation of two open-loop unstable and locally uncontrollable example problems.
An approach for decentralized process modeling
Turetken, Oktay; Demirörs, Onur (2007-05-20)
This paper describes a method for organizations to perform process modeling in a decentralized and concurrent manner. The approach is based on the idea that modeling organizations' processes can be performed by individuals actually performing the processes. Instead of having a central and devoted group of people to analyze, understand, model and improve processes, real performers are held responsible to model and improve their own processes concurrently. The paper also summarizes the lessons learned by appl...
A method for concurrency control in distributed DBMSs: Permission Test Method
Halıcı, Uğur (Association for Computing Machinery (ACM), 1987-01-09)
In this paper, a method for concurrency control in distributed DBMSs, called Permission Test Method is proposed. The PT method satisfies the basic requirements for concurrency control, that is, it executes the transactions in a serializable order, deadlocks do not appear and indefinite postponment is prevented by the method. In PT method, transactions, which are permitted to run, are not aborted unless a related site failure occurs. Furthermore, the complexity analysis indicates that the algorithm will work...
Citation Formats
M. Akpınar, “A general framework for the deterministic medium access on the Controller Area Network,” Ph.D. - Doctoral Program, Middle East Technical University, 2022.