Numerical simulations of environment control and life support system in space station-oriented real-time system

An environment control and life support system (ECLSS) is an important system in a space station because it can provide a basic living environment for astronauts. The ECLSS is a typical time-variant complex system, hence there exits time-consuming technical difficulty during its development. The real-time simulation technology can help to accelerate its research process because some models of complex hardware need not to be built and calibrated at all. For a real-time simulation system with time-varying parameters, an implicit fixed time step numerical integration method is normally used as its solver. However, its computational efficiency is too low especially for the complex ECLSS simulation system on a single personal computer (PC) cluster. An explicit fixed time step integration method is computationally efficient, but their potential instability problems, which are caused by the time-varying parameters, limit its application to the ECLSS system. In this paper, an improved model method based on the explicit Euler method is proposed to simulate the complex time-variant ECLSS on a PC cluster. A simplified ECLSS system is established as an example to explain this proposed method. The eigenvalue estimation theory is used to analyze the numerical stability of the simplified system. Further, the potential instability problem of the explicit method can be avoided by an adaptive operator. Both of the stability and the accuracy of the proposed method are investigated carefully. It can be concluded from simulation results that this proposed method can provide a solution to realize the real-time simulation for the complex time-variant ECLSS on a PC cluster.