Thrust Vector Controller Comparison for a Finless Rocket

The paper focuses on comparing applicability, tuning, and performance of different controllers implemented and tested on a finless rocket during its boost phase. The objective was to evaluate the advantages and disadvantages of each controller, such that the most appropriate one would then be developed and implemented in real-time in the finless rocket. The compared controllers were Linear Quadratic Regulator (LQR), Linear Quadratic Gaussian (LQG), and Proportional Integral Derivative (PID). To control the attitude of the rocket, emphasis is given to the Thrust Vector Control (TVC) component (sub-system) through the gimballing of the rocket engine. The launcher is commanded through the control input thrust gimbal angle δ , while the output parameter is expressed in terms of the pitch angle θ . After deriving a linearized state–space model, rocket stability is addressed before controller implementation and testing. The comparative study showed that both LQR and LQG track pitch angle changes rapidly, thus providing efficient closed-loop dynamic tracking. Tuning of the LQR controller, through the Q and R weighting matrices, illustrates how variations directly affect performance of the closed-loop system by varying the values of the feedback gain (K). The LQG controller provides a more realistic profile because, in general, not all variables are measurable and available for feedback. However, disturbances affecting the system are better handled and reduced with the PID controller, thus overcoming steady-state errors due to aerodynamic and model uncertainty. Overall controller performance is evaluated in terms of overshoot, settling and rise time, and steady-state error

An Advanced Hexacopter for Mars Exploration: Attitude Control and Autonomous Navigation

Mars exploration has recently witnessed major interest within the scientific community, particularly because unmanned aerial robotic platforms offer reliable alternatives for acquiring and collecting data and information from the Red Planet. However, the specific conditions of the Martian environment result in a restricted flight envelope when flying close to Mars and then landing on the surface of Mars. Therefore, in addition to the requirement to develop an aerial platform suitable for operations on Mars, autonomous navigation strategies and robust controllers are also needed for exploration tasks. It is argued that hexacopters with their relatively compact design represent a promising solution for autonomous exploration tasks on Mars, overcoming at the same time the limitations of wheel-based rovers. This research focuses on the design of a Mars Hexacopter (MHex) for a scouting mission in the Jezero region of Mars. The configuration and architecture of the hexacopter follow NASA conceptual study of the Mars Science Helicopter (MSH). Then, the mission profile for mapping Belva crater is examined, followed by a detailed approach to implement and test observer-based navigation and control strategies. A comprehensive simulated experiments environment based on the integration of ROS and Ardupilot,is also presented, used to validate the overall system architecture and mission parameters considering both the morphological shape of the explored crater and the atmospheric conditions of Mars