Nelson Groom

Design Formulas for Permanent-Magnet Bearings

As the energy densities in permanent magnet materials increases, permanent magnet (PM) bearings are becoming increasingly attractive machine elements for applications ranging from turbo machinery to energy storage flywheels. Desirable qualities include high speed, low wear, energy savings, and freedom from lubricants that can degrade or contaminate other system components. In this paper we develop analytical expressions for stiffness and peak load in stacked-structure radial magnetic bearings that extend the seminal work of Backers, and Yonnet and co-workers. In addition to the derivation of simple design rules, the axial peak force and negative axial stiffness are calculated.

THE ANNULAR SUSPENSION AND POINTING SYSTEM

Abstract The Annular Suspension and Pointing System (ASPS) is a general purpose mount designed to provide orientation, mechanical isolation, and fine pointing for space experiments. The ASPS consists of two assemblies, the first being a set of two gimbals attached to a carrier spacecraft (e.g., Space Shuttle) and providing coarse pointing, and the second a magnetic vernier pointing and isolation assembly attached to the inner gimbal of the first assembly and providing fine pointing. The magnetic vernier assembly uses an annular rim as its pitch and yaw controlled element. The rim surrounds an experiment mounting plate. Roll control is provided by a noncontacting roll motor which also uses the rim as its controlled element. Discussion of the evolution of this concept, required related technology, data from analyses and simulations predicting pointing accuracies, and a description of a flight test unit will be presented.

Annular Suspension and Pointing System

The Annular Suspension and Pointing System (ASPS) is a general-purpose mount designed to provide orientation, mechanical isolation, and fine pointing for space experiments. The ASPS consists of two assemblies, the first being a set of two gimbals attached to a carrier spacecraft (e.g., Space Shuttle) and providing coarse pointing, and the second a magnetic vernier-pointing and isolation assembly attached to the inner gimbal of the first assembly and providing fine pointing. Discussion of the evolution of this concept, required technology, and data from analyses and simulations predicting pointing accuracies that allowed the specification of hardware design requirements is presented.

Optimal member damper controller design for large space structures

Consideration is given to the selection of velocity feedback gains for individual dampers for the members of a structurally controlled large flexible space structure. The problem is formulated as an optimal output feedback regulator problem, and necessary conditions are derived for minimizing a quadratic performance function. The diagonal nature of the gain matrix is taken into account, along with knowledge of noise covariances. It is pointed out that the method presented offers a systematic approach to the design of a class of controllers for enhancing structural damping, which have significant potential if used in conjunction with a reduced-order optimal controller for rigid-body modes and selected structural modes.

The Annular Suspension and Pointing System

Abstract The Annular Suspension and Pointing System (ASPS) is a general purpose mount designed to provide orientation, mechanical isolation, and fine pointing for space experiments. The ASPS consists of two assemblies, the first being a set of two gimbals attached to a carrier spacecraft (e.g., Space Shuttle) and providing coarse pointing, and the second a magnetic vernier pointing and isolation assembly attached to the inner gimbal of the first assembly and providing fine pointing. The magnetic vernier assembly uses an annular rim as its pitch and yaw controlled element. The rim surrounds an experiment mounting plate. Roll control is provided by a noncontacting roll motor which also uses the rim as its controlled element. Discussion of the evolution of this concept, required related technology, data from analyses and simulations predicting pointing accuracies, and a description of a flight test unit will be presented.

Mechatronic Design and Optimization of an Artificial Heart

Abstract The mechatronic left-ventricular assist devices (LVAD’s or artificial hearts), Streamliner HG3b and HG3c, have successfully been implanted in calves. The first was implanted for 4 hours (Figure 1) and the second for 34 days. The tests confirmed the feasibility of low power levitation (1.5 watts coil power) and very low blood damage in mag-lev ventricular assist devices. In this paper, we describe the unique mechatronic modeling and design of these compact systems. Key features of this LVAD concept are the passive radial magnetic suspension and an active voice-coil thrust bearing. This system is one of the smallest mag-lev systems designed to date.