Development of a Control System for a Liquid Rocket Engine Test Stand

Tartarus is a student-led liquid rocketry project under the Space Hardware Club (SHC) at the University of Alabama in Huntsville (UAH). This paper will detail the design of a control system for a mobile test stand (MTS), designed in-house, by the team. The control system is how the team will command the system to fire and react to minimize the risk of harm to personnel. Due to the complexity of the mobile test stand, the control system must be made reliable, easily-serviced, and expandable for future needs. The main tasks of the control system are to command open and close valves, collect temperature, pressure, and thrust data, and trigger an abort if readings become unsafe. To meet these requirements, the control system will be primarily made from commercial off-the-shelf (COTS) components. The control system will be split into two main sections based on location: the MTS controller which is located inside the trailer, and the base station. The base station consists of the controls computer and all of the physical/analogue abort systems required for safe firing. The MTS controller is further broken into two systems: the MTS computer and the command control interface (CCI) boards. The MTS computer is a Raspberry Pi 4s that communicates between the CCI boards and the base station. The CCI boards are where all of the XLR ports for all sensors and solenoids are located. These custom-printed circuit boards (PCBs) are assembled from COTS components. The benefit of using COTS components, especially on the CCI boards, is that if a component fails, it can be replaced easily and at a relatively low cost. All of the subsystems will integrate together to create a robust and modular controls system for use on the team’s mobile test stand. The details of how these subsystems are designed will be explained later in the paper.