Michael R. Ricci

Modeling and Control of an Electromagnetic Variable Valve Actuation System

A novel electromechanical valve actuation system comprised of a linear actuator, valve, and energy storing cam/spring mechanism is presented. The system dynamics are modeled using Lagrangian mechanics, and a minimum-energy point-to-point optimal control problem is solved to find an optimal trajectory and input. The optimal input is used as a feedforward component in a transition controller to move the valve between the open and closed positions. Between transitions, a simple linear controller stabilizes the valve in the open and closed positions. A high-order model capturing the distributed nature of valve springs is used to validate state constraints related to positive cam/follower forces and a nonslip condition on the cam/follower. Finally, a prototype system is fabricated and tested with promising results.

Analysis of Levitational Systems for a Superconducting Launch Ring

The launch ring consists of a maglev system in which a levitated vehicle is accelerated in an evacuated circular tunnel until it reaches a desired velocity and then releases a projectile into a path leading to the atmosphere. This paper analyses several levitational concepts for a system that employs superconductors in the stator and on the vehicle. Both an attractive and a shear-force configuration are shown to offer complete static stability over the complete velocity range from 0 to 10 km/s.

The Launch Ring - Circular EM Accelerators for Low Cost Orbital Launch

[Abstract] Despite huge potential benefits, no electromagnetic Earth-to-orbit launcher has yet been constructed, primarily due to the difficulty of providing the enormous power required. The Launch Ring adopts circular acceleration and much of the technology of modern synchrotrons to achieve orbital speeds without the need for extremely high power. Superconducting cables and coils are employed to create a passively stable high force magnetic suspension for a maglev “sled”, which is accelerated around an enclosed, evacuated circular track of large circumference until it reaches launch speed. A projectile is then released through a tangential exit tube and, potentially, into orbit. Radial accelerations exceeding 10,000 g’s and launch speeds exceeding 10 kilometers per second appear achievable with both a relatively small accelerator for launching 10 kg micro-satellites and a larger accelerator for 1000 kg projectiles. Development of Launch Rings could lead to remotely operated assembly facilities in orbit and a radically less expensive approach to space exploitation.