Autonomous safety and reliability features of the K-1 avionics system

Abstract

Kistler Aerospace Corporation is developing the K-1, a fully reusable, two-stage-to-orbit launch vehicle. Both stages return to the launch site using parachutes and airbags. Initial flight operations will occur from Woomera, Australia. K-1 guidance is performed autonomously. Each stage of the K-1 employs a triplex, fault tolerant avionics architecture, including three fault tolerant computers and three radiation hardened Embedded GPS/INS units with a hardware voter. The K-1 has an Integrated Vehicle Health Management (IVHM) system on each stage residing in the three vehicle computers based on similar systems in commercial aircraft. During first-stage ascent, the IVHM system performs an Instantaneous Impact Prediction (IIP) calculation 25 times per second, initiating an abort in the event the vehicle is outside a predetermined safety corridor for at least 3 consecutive calculations. In this event, commands are issued to terminate thrust, separate the stages, dump all propellant in the first-stage, and initiate a normal landing sequence. The second-stage flight computer calculates its ability to reach orbit along its state vector, initiating an abort sequence similar to the first stage if it cannot. On a nominal mission, following separation, the second-stage also performs calculations to assure its impact point is within a safety corridor. The K-1's guidance and control design is being tested through simulation with hardware-in-the-loop at Draper Laboratory. Kistler's verification strategy assures reliable and safe operation of the K-1.