Research On Schedule Algorithms Of Time-triggered Network

As the complexity of industrial control systems is increasing,the demand of intercommunication inside the system is also growing rapidly.Time-triggered real-time networks are being widely used because it is highly deterministic.In time-triggered networks,the transmission of data flows are strictly performed according to the schedule.Thus,the schedule synthesis algorithm determines the performance of the network.Currently,the existing algorithms have weaks in schedulability,fault tolerance and schedule speed.This paper researched over the time-triggered network schedule problem by analyzing the constraints of a network based on an existing time-triggered Ethernet switch.It also introduced the toolkit for an existing time-triggered real-time Ethernet switch.The main contributions are summarized as follows:1.This paper extends the existing slot-based schedule models and proposed a finegrained schedule model.It analyzed the constraints of a valid schedule based on the architecture of the switch.It also proved the fact that the period of any two flows should be rational,which is assumed in existing works.The evaluations shows that this method can effectively improve the number of schedulable flows.2.This paper introduces the existing fault-tolerant routing algorithm into timetriggered networks and found a counterexample that the existing schedule model cannot describe such a use case.Thus,this paper proposed an extended schedule model and provided a corresponding algorithm.To improve the performance of the algorithm,multiple optimizations are applied.Evaluation shows that this work increases the available bandwidth for non-critical traffic by up to more than 50%.This paper also describes an architecture that supports the fault-tolerant routing algorithm.3.This paper introduces the toolkit for the time-triggered real-time Ethernet switch.The toolkit automatically collects the network topology by using SNMP and LLDP.After user manually specify the transmission requirement,the toolkit generates a schedule and dispatches the schedule to all nodes via SNMP and TFTP.The toolkit provides user-friendly interface,and reduces manual operation required and reduces the possibility of misuse.4.Most of the schedule algorithms are unsuitable for trains which requires fast re-configuration.This paper introduced a greedy algorithm by fixing the relative timing between flows on the network and this algorithm greatly reduced the time required to find a valid schedule compared to the traditional solver and searchbased schedule generators.Thus,this algorithm can be used within environments of reconnection in service.The algorithm is integrated to the toolkit.