Design of Guidance Algorithms for Mars Landing Applications

Sixty years ago, the first landing attempt on the Red Planet was made by the lander that was part of the Soviet Union’s mission called Sputnik 24. From that day to the present, several strides have been made in the field of precision landings on large planetary bodies having an atmosphere. This progression has permitted to reverse the trend that saw most of these manoeuvres fail and also to reach levels of efficiency that even allow rovers and drones to land. In addition, the great interest in the exploration of planets in the solar system, that has been recently ignited, has helped research in this field to become extremely fertile. Consequently, the world of Guidance, Navigation and Control (GNC) systems has also been facing a great development due to the fact that they are a key component for the success of these manoeuvres. Indeed, a great variety of proposals for new control logics and studies as far as these are concerned have emerged in recent years from universities and public agencies. The future of GNC systems, however, seems to have taken a preponderant direction, converging toward the use of Zero Effort Miss - Zero Effort Velocity (ZEM-ZEV) type guidance algorithms, developed and now established for missile applications. These have numerous advantages that make them particularly attractive for powered descent phases in Entry, Descent and Landing (EDL) manoeuvres. ZEM-ZEV guidance algorithms also turn out to be particularly well suited to be hybridized with Sliding mode control laws, thus achieving excellent results as far as performance and robustness, both of which are important features for this applications. The purpose of this work is therefore to develop a landing simulator in the Matlab-Simulink environment by implementing in it a guidance law for position control and a control law for attitude control. The guidance law implemented for the trajectory is a hybrid algorithm between ZEM-ZEV and Sliding Mode, called Optimal Sliding Guidance and proposed by Daniel R. Wibben and Roberto Furfaro (Department of Aerospace and Mechanical Engineering, University of Arizona). On the other hand, the control law that deals with tracking the desired attitude is the Super-Twisting Sliding Mode The performance of the aforementioned control systems is then observed by simulating a realistic Mars landing mission. Specifically, the mission referred to is NASA's Phoenix mission, which took place in May 2008, during which the Phoenix Mars Lander successfully landed on the Martian surface.