An algorithm based fault tolerance technique for safety-critical applications

The design of safety critical systems is a difficult and time consuming task. The traditional design of safety critical systems involves the use of proprietary hardware and software. The full custom design approach is becoming unacceptable because performing a complete redesign for each different class of control applications is unacceptable. Additionally, traditional safety critical systems are designed based on locating all faults in the system which can affect safety via diagnostics. The increasing complexity of the control algorithms which must be processed in a safety critical fashion makes the fault space of the system increase in size to the point where the design of diagnostics becomes quite difficult and time consuming. One promising methodology which can assist in reducing the design effort associated with safety critical systems while using commercial off-the-shelf (COTS) components is algorithm-based fault tolerance (ABFT). Unfortunately, existing ABFT techniques are currently not suitable for safety critical applications. A new safety critical ABFT (SC-ABFT) technique is presented. The checking scheme for the SC-ABFT method is derived based on verifying the correctness of a given control application as it is being evaluated. Also, the probability of detecting a safety-critical error can made as close to 1.0 as desired by varying certain parameters.