As interest in colonizing the Moon increases, developing a sustainable method of transporting equipment and resources to and from the lunar surface will be necessary. LANDER’s approach to this problem is a system that uses one thruster capable of vectoring thrust to control vehicle attitude and perform propulsive landings with minimal fuel use. The key to the design challenge is creating a suitable test environment for a system that can simulate variables such as lunar gravity and a lack of atmosphere while on Earth. Project LANDER endeavored to provide a potential solution by designing a complex simulation utilizing live data from a hardware-in-the-loop system. Unfortunately, due to an abbreviated timetable and low-quality components, LANDER did not meet all requirements for a successful Operational Demonstration. However, LANDER was a proof-of-concept system, and the team hopes to lay the foundation for future development in this area.
The fully assembled system and the system's CAD can be seen in the following figure. LANDER consists of 5 subsystems, Control Software, Avionics, Control Mechanisms, Structure, and Test Stand. These subsystems all come together to produce a test stand capable of simulating a vehicle landing on the lunar surface. The test stand involves a complex hardware-in-the-loop computer simulation running on a microcontroller.
The simulated vehicle comprises a feedback loop where the rocket motor causing forces on load cells translates to forces in the simulation. The control system utilizes a PID that gives the simulated vehicle commands; the commands are then rendered into hardware as TVC commands. The physical vehicle encompasses the avionics, TVC, and load cells. The physical vehicle receives commands from the simulated vehicle and returns calculated thrust data to the control software.
The experimental thrust curve shows that the four load cells matched the thrust curve for the Estes F15 within 6.2 Newton Seconds or 13.2% of expected. Unfortunately, due to multiple changes in project and scope, LANDER initially chose very cheap load cells since the test stand demonstration originally only served as verification for much more extensive goals, such as an actual propulsive landing. Therefore, acquiring usable data from the load cells took much more time and resources than the team initially expected. This time sink could have easily been mitigated if the team had spent more money on load cells to handle the new mission profile. However, the team overcame the challenge thanks to proper risk mitigation.
The Grand Finale
At the conclusion and verification of the Operational Demonstration, LANDER has compiled a Final Report and a System Verification Report. The Final Report compiles two semesters of work into one succinct document that highlights all of the findings from the project, while the System Verification Report is the final presentation from the team to present their findings.