Reliability analysis of real-time controllers with dual-modular temporal redundancy

We suggest and analyze a new method called dual-modular temporal redundancy (DMTR) to greatly improve the system reliability by effectively using temporal as well as modular redundancies. To improve reliability of real-time controllers, in addition to improving reliability of components and subsystems, various fault tolerance methods using redundancy are devised which include hardware, software, time, and information redundancies. The DMTR utilizes two fast processors effectively since recent progress on microprocessors and DSPs (Digital Signal Processors) provided enormous computational capacity-sufficient to perform multiple computations of given tasks within the desired deadlines-with reasonably low cost. We formulate a simple but efficient temporal redundancy method using dual-modular redundancy, which greatly improves system reliability for correlated as well as independent faults. We also analyze the system reliability thoroughly, assuming that faults occur and disappear with exponential probability distribution. Various evaluation results demonstrate the outstanding reliability of the proposed method