Real-time Hardware-in-the-loop Test for a Small Upper Stage Embedded Control System

In this paper, the development of a real-time hardware-in-the-loop (UM) test for a spacecraft is investigated. The spacecraft mission is to transfer a satellite from 400km circular to 400-7000km elliptical orbit by a small upper stage. The main phases of the mission are de-tumbling, pointing, spin-up, and orbital transfer maneuvers. The developed HIL test aims at demonstrating the performance of the guidance, navigation, and control (GNC) algorithms, simulating the mission operation plan (MOP), completing the end-to-end hardware verification, and testing throughout the whole mission. In the presented framework, five modules are considered: 1) Onboard hardware (OBH) module; 2) onboard software (OBS) module; 3) Flight simulator (FS) module; 4) Logger and command computer (LCC) module; 5) Ground station hardware (GSH). The GNC algorithms and mission operation plan (MOP) are programmed in the OBS while it communicates with a six degrees of freedom flight simulator, implemented in C# language in the visual studio environment. The HIL test is performed while sensors have been substituted with dummy thermal ones to simulate their energy consumption and electrical functions, because the environmental conditions of space and the sensors cannot be duplicated in the laboratory environment. The FS module can be executed in a real-time manner with the frequency of 1 kHz and even faster. All results have been proven to be satisfactory with respect to orbit transfer mission and consequently, the onboard hardware and software are verified to be reliable enough after several repeats of the test.