  The paper addresses the issue of reliability of complex embedded control
systems in the safety-critical environment. In this paper, we propose a novel
approach to design controller that (i) guarantees the safety of nonlinear
physical systems, (ii) enables safe system restart during runtime, and (iii)
allows the use of complex, unverified controllers (e.g., neural networks) that
drive the physical systems towards complex specifications. We use
abstraction-based controller synthesis approach to design a formally verified
controller that provides application and system-level fault tolerance along
with safety guarantee. Moreover, our approach is implementable using
commercial-off-the-shelf (COTS) processing unit. To demonstrate the efficacy of
our solution and to verify the safety of the system under various types of
faults injected in applications and in the underlying real-time operating
system (RTOS), we implemented the proposed controller for the inverted pendulum
and three degree-of-freedom (3-DOF) helicopter.
