Controller Design for a Swirl Injection Hybrid Launch Vehicle

This research is focused on the design of controllers for stabilizing a launch vehicle with an internally originating torque. The motivation for this research arises from the new development of rocket engines which swirl combustion gases to gain combustion stability benefits, and in the case of hybrid rocket engines, fuel regression benefits as well. The stability of the launch vehicle dynamics due to the internal torque has not been discussed before. To the author’s knowledge, this is the first research to address the stabilization problem of the launch vehicle with internal torque. Due to the new design/characteristics of these engines, there are not many research articles on the proposed topic and the exact internal dynamics remains mostly unknown, so this research focuses on designing controllers with the ability to compensate for unknown torques. In order to develop the controllers, this research also designs a dynamics model for these launch vehicles, where the changing location of the center of mass is shown through simulation to be negligible for a real hybrid launch vehicle. Due to the proprietary nature of the exact launch vehicle data, a launch vehicle that is based on the approximate real data of a real hybrid launch vehicle was developed for the simulation of the controllers that are designed in this research. The proposed controllers include a linear quadratic regulator, PD-type controller, affine parameter-dependent Lyapunov function based controller, and an adaptive controller. These controllers must meet the goal of stabilizing the launch vehicle within the main engine’s burn time. This constraint allows for these controllers to be implemented on either the first or upper stages of a launch vehicle. This research shows that the linear quadratic regulator, PD-type controller, and adaptive controller all provide adequate control over the launch vehicle with an engine originating internal toque. The performance of all four proposed controllers is demonstrated by numerical simulations. This research concludes with the recommendation of either the LQR controller or the PD-type controller for a launch vehicle similar to the one developed here. Future research may include the acquisition of real internal torque data from one of the institutions that is currently researching the design of swirl combustion engines. This data would be used to design an internal torque model for the engine, which would then be used in the equations of motion of the launch vehicle and the subsequent controller designs

Dual Quaternion Relative Dynamics for Gravity Recovery Missions

A dual quaternion modeling approach is compared to traditional modeling methods for formation flying spacecraft utilized for gravity recovery missions. A modeling method that has traditionally been used for gravity recovery missions is presented which models the motion of two formation flying spacecraft and a test mass. This is followed by the dual quaternion-based formulation for the equations of motion of the twelve degree-of-freedom coupled relative dynamics of formation flying spacecraft and a test mass. Lastly, utilizing data products from the Gravity Recovery and Climate Experiment Follow-On mission, a comparison of these two modeling methods is presented which proves the advantage of the proposed dual quaternion-based modeling approach

Defining Natural History: Assessment of the Ability of College Students to Aid in Characterizing Clinical Progression of Niemann-Pick Disease, Type C

Niemann-Pick Disease, type C (NPC) is a fatal, neurodegenerative, lysosomal storage disorder. It is a rare disease with broad phenotypic spectrum and variable age of onset. These issues make it difficult to develop a universally accepted clinical outcome measure to assess urgently needed therapies. To this end, clinical investigators have defined emerging, disease severity scales. The average time from initial symptom to diagnosis is approximately 4 years. Further, some patients may not travel to specialized clinical centers even after diagnosis. We were therefore interested in investigating whether appropriately trained, community-based assessment of patient records could assist in defining disease progression using clinical severity scores. In this study we evolved a secure, step wise process to show that pre-existing medical records may be correctly assessed by non-clinical practitioners trained to quantify disease progression. Sixty-four undergraduate students at the University of Notre Dame were expertly trained in clinical disease assessment and recognition of major and minor symptoms of NPC. Seven clinical records, randomly selected from a total of thirty seven used to establish a leading clinical severity scale, were correctly assessed to show expected characteristics of linear disease progression. Student assessment of two new records donated by NPC families to our study also revealed linear progression of disease, but both showed accelerated disease progression, relative to the current severity scale, especially at the later stages. Together, these data suggest that college students may be trained in assessment of patient records, and thus provide insight into the natural history of a disease

Digital game elements, user experience and learning

The primary aim of this paper is to identify and theoretically validate the relationships between core game design elements and mechanics, user motivation and engagement and consequently learning. Additionally, it tries to highlight the moderating role of player personality traits on learning outcomes and acceptance and suggest ways to incorporate them in the game design process. To that end, it outlines the role of narrative, aesthetics and core game mechanics in facilitating higher learning outcomes through intrinsic motivation and engagement. At the same time, it discusses how player goal orientation, openness to experience, conscientiousness, sensation seeking and need for cognition influence the translation of the gameplay experience into valuable learning outcomes and user acceptance of the technology