For high-speed bearingless disk drives, certain topologies seem advantageous. The authors have published works on a bearingless disk drive for high speeds that is characterized by a slotless stator and a toroid winding set. Several different variations of this setup are imaginable. The ones which this paper focuses on are the variation of the number of phases, of the number of coils, and of the applied coil connection. A comparison of the constructed and tested setup with the possible variations is presented in the course of this paper.

Design problems in engineering typically involve a large solution space and several potentially conflicting criteria. Selecting a compromise solution is often supported by optimization algorithms that compute hundreds of Pareto‐optimal solutions, thus informing a decision by the engineer. However, the complexity of evaluating and comparing alternatives increases with the number of criteria that need to be considered at the same time. We present a design study on Pareto front visualization to support engineers in applying their expertise and subjective preferences for selection of the most‐preferred solution. We provide a characterization of data and tasks from the parametric design of electric motors. The requirements identified were the basis for our development ofPAVED, an interactive parallel coordinates visualization for exploration of multi‐criteria alternatives. We reflect on our user‐centered design process that included iterative refinement with real data in close collaboration with a domain expert as well as a summative evaluation in the field. The results suggest a high usability of our visualization as part of a real‐world engineering design workflow. Our lessons learned can serve as guidance to future visualization developers targeting multi‐criteria optimization problems in engineering design or alternative domains.

Following the trend towards smaller drives operating at increased speeds, the present work examines the suitability of bearingless drives for high speed operation. With rising rotational frequency, the requirements for the drive components differ significantly from a design specification for low speeds. Therefore, the design of the stator, rotor and winding system is described in detail. In order to verify the conducted analytical and FE calculations, a laboratory prototype was constructed reaching - to the knowledge of the authors - a world record speed for bearingless drives of 115.000rpm. Eventually, measurements showing specific losses and operational behavior of the drive are presented.

Bearingless drives have been intensely researched for over a decade since they represent a compact motor-bearing system fulfilling very special requirements. They provide all advantages of a typical magnetically levitated system, including the absence of mechanical wear and bearing friction. Therefore, an application for high-speed processes seems tempting. Nevertheless, there are no high-speed bearingless drives in industry so far and even in scientific research, their rated speed hardly exceeds 20krpm. One of the main obstacles on the way to rotational speeds of up to 100krpm are the occurring losses in stator, winding and air gap. This work deals with their analytical description, appropriate design steps of the drive system and a concluding experimental verification.

This paper presents a robust visual servoing approach for automatic guidance of an instrument. The visual sensor is an ultrasound probe that observes an instrument which is inserted into the beating heart of a patient and manipulated by a robot. The present paper provides stability analysis, robustification of the control law and an in vivo experiment.

Due to several special characteristics of magnetic suspension, bearingless drives may be suitable for turbine application. These characteristics range from operability without lubrication, the absence of mechanical friction and of sliding seals to variable stiffness and damping, inherent bearing diagnostics function, low maintenance and long life time. However, there are several drawbacks which might be critical to turbine operation. Using a bearingless disk drive prototype, experiments with a turbine and compressor wheel at high rotational speeds shall provide conclusive information about the rotor behavior over the entire speed range. The results will show if, and under which assumptions, the use of bearingless disk drives for micro turbine applications seems feasible.