@article{9571,
  abstract     = {{Several positioning tasks demand translatory drive instead of rotary motion. To achieve drives that are capable, e.g., to drive the sunroof of a car or to lift a car's window, multiple miniaturized motors can be combined. But in this case many other questions arise: The electromechanical behavior of the individual motors differs slightly, the motor characteristics are strongly dependent on the driving parameters and the driven load, many applications need some extra power for special cases like overcoming higher forces periodically. Thus, the bundle of motors has to act well-organized and at last controlled to get an optimized drive that is not oversized and costly.}},
  author       = {{Mracek, Maik and Hemsel, Tobias and Sattel, Thomas and Vasiljev, Piotr and Wallaschek, Jörg}},
  issn         = {{1385-3449}},
  journal      = {{Journal of Electroceramics}},
  keywords     = {{Ultrasonic linear motor, High power, Control, Modeling, Characteristics}},
  number       = {{3-4}},
  pages        = {{153--158}},
  publisher    = {{Springer US}},
  title        = {{{Driving concepts for bundled ultrasonic linear motors}}},
  doi          = {{10.1007/s10832-007-9123-5}},
  volume       = {{20}},
  year         = {{2008}},
}

@article{9546,
  abstract     = {{Rotary ultrasonic motors have found broad industrial application in camera lens drives and other systems. Linear ultrasonic motors in contrast have only found limited applications. The main reason for the limited range of application of these very attractive devices seems to be their small force and power range. Attempts to build linear ultrasonic motors for high forces and high power applications have not been truly successful yet. To achieve larger force and higher power, multiple miniaturized motors can be combined. This approach, however, is not as simple as it appears at first glance. The electromechanical behaviour of the individual motors differs slightly due to manufacturing and assembly tolerances. The individual motor characteristics are strongly dependent on the driving parameters (frequency, voltage, temperature, pre-stress, etc.) and the driven load and the collective behaviour of the swarm of motors is not just the linear superposition of the individual drive's forces. Thus, the bundle of motors has to be synchronized and controlled appropriately in order to obtain an optimized drive that is not oversized and costly. We have investigated driving and control strategies of a set of linear ultrasonic motors. Our contribution will be divided into three main parts. In part I ultrasonic linear motors will be introduced. In part II driving strategies for a single motor as well as for a bundle of motors will be presented. These concepts will be verified by simulation results and experimental data. In part III a simplified model for the motor's electromechanical behaviour will be given.}},
  author       = {{Mracek, Maik and Hemsel, Tobias}},
  issn         = {{0041-624X}},
  journal      = {{Ultrasonics}},
  keywords     = {{Ultrasonic linear motor}},
  pages        = {{e597 -- e602}},
  title        = {{{Synergetic driving concepts for bundled miniature ultrasonic linear motors}}},
  doi          = {{10.1016/j.ultras.2006.05.201}},
  volume       = {{44, Supplement}},
  year         = {{2006}},
}

@inproceedings{8915,
  abstract     = {{Ultrasonic linear motors have now been investigated for several years. Their key features are high thrust forces related to their volume and good position-accuracy. This contribution consists of two main parts. In the first part we describe the state-of-the-art of linear piezoelectric motors. Characteristics like no-load velocity, maximum thrust force and other technical properties of commercially available devices will be reported as well as those of prototypes. In the second part we report an ongoing research and development project aiming at a linear piezoelectric motor, which is capable of surpassing some of the shortcomings of other piezoelectric motors}},
  author       = {{Hemsel, Tobias and Wallaschek, Jörg}},
  booktitle    = {{Ultrasonics Symposium, 2000 IEEE}},
  issn         = {{1051-0117}},
  keywords     = {{linear motors, ultrasonic motors, linear piezoelectric motor, maximum thrust force, no-load velocity, ultrasonic linear motor, Electromagnetic devices, Electromagnetic fields, Frequency, Friction, Gears, Materials science and technology, Piezoelectric materials, Research and development, Vibrations, Wheels}},
  pages        = {{663--666 vol.1}},
  title        = {{{State of the art and development trends of ultrasonic linear motors}}},
  doi          = {{10.1109/ULTSYM.2000.922635}},
  volume       = {{1}},
  year         = {{2000}},
}