Fault-tolerant Real-time Control Research Articles

XFTRTS - A XtratuM Based Fault-Tolerant Real-Time Control System

Nowadays there are a few works which are concerned with the virtualization technology and the fault-tolerance technology, because virtualization system can provide an environment allowing multiple operating systems running in concurrent way. In this paper, we based on a real-time hypervisor-XtratuM, propose the architecture of a fault-tolerant real-time control system (XFTRTS), which provide local backup execution and to support different level diversity including N-version programming on a single host. Furthermore, we implement a prototype of XFTRTS and test its important performance metric–latency, which is within two microseconds.

Fault tolerant real time control system for steer-by-wire electro-hydraulic systems

A steer-by-wire (SBW) control system is presented with emphasis on safety issues. The applications are in articulated vehicles such as the wheel type loaders, articulated trucks, and others. The electro-hydraulic (EH) power circuit is controlled by two embedded electronic control modules (ECM), the primary ECM and backup ECM. The two ECMs monitor each others condition. If one detects fault in the other, it takes over the control functions. There are two main control algorithms that run in the ECMs in real-time: the steering valve control algorithm and the failure detection algorithm. The valve control algorithm basically generates command signal to the steering valve based on operator steering column signal as well as other machine condition sensors. The failure detection algorithm implements a fault detection logic for both input sensors and output drivers, and flags the corresponding warning for to the operator, and take a predefined action depending on the type of the failure detected. A unique fault strategy organization is implemented by inspecting the failure behavior on both the component and the system levels. The failure detection algorithm also determines the most likely “good” sensor signal from a set of redundant sensors for each critical measurement. Based on these good sensors data, the steering control algorithm sends two output signals: the control signal to the steering EH circuit valve and the control signal to the steering wheel force feedback device (i.e. a brake or a motor) to give operator feedback about the steering conditions. Finite state machine (FSM) concept is used to design the fault handling algorithms for both the component level and the system level failure. The probability of the system being at normal steering state or at any other steering failure state is determined. Failure mode probabilities of steering system components are also determined.