Flexray Applications in Control Loops Focussing on Steer-by-wire Models

The aim of this report is to show, how to embed the bus system FlexRay (FR) into a practical application of motion control. Thereby, the FR is the only connection between the controller and the process. This means, that it is an element of the control loop. The object of this investigation is a test rig in terms of a steer-by-wire hardware model with two FR test boards. Especially, the interrelation between the transport delays of the bus and the scheduling and synchronization of the operating system on each bus node is focused upon. Constant and predictable transport delays can be obtained by synchronizing the operating systems on each node to the bus. This is implemented with the FR communication controller requesting interrupts periodically during each bus cycle. The transport delay caused by the FR is also considered for the controller design. The test results show that the FR reacts as predicted. Further, this report gives statements about the FRs suitability for central control architectures and applications demanding hard real-time. The FR protocol is evaluated to meet the requirements for hard real-time if the operating system on each node is synchronized to the bus.