Hannover, April 2, 1995 Transport and distribution are often too inflexible and too slow to meet customer needs. One possible remedy to this unsatisfactory situation could lie in the use of decentralized and autonomous transport vehicles. However, an essential prerequisite here is the availability of a system capable of transferring information and energy in a non-contact manner. With conventional solutions, the transmission of electrical energy and information (data) in moving systems always entails difficulties because drum cables or wiping contacts are prone to trouble and interference. It is thus desirable that cables or contacts be eliminated. The dream of being able to operate materials-handling systems, robots, and elevators without the need for drum cables or sliding contacts could now be a step closer to fulfillment. Moreover, this new technology could also bring significant benefits to other applications: electric vehicles could be charged without the need for electrical contact, and electrical contacts could be totally removed from areas subject to explosion hazards. Given the potential usefulness of such a technology, it is no surprise that the Daimler Benz laboratories are presently working on the non-contact transfer of force, power - and information.The goal of current research is to provide innovative systems solutions for a wide spectrum of applications. As far as materials-handling technology is concerned, a modular and flexible system capable of rapidly and intelligently solving a multitude of transportation tasks using standardized components and systems is being developed in cooperation with Daimler-Benz Industrie. Application possibilities exist wherever transportation tasks are to be accomplished using a large number of autonomous decentralized vehicles.
Using the transformer principle, electrical energy is transferred via induction to the moving system. However the frequency used is much higher than that used by transformers: instead of 50 Hz, the new systems work at about 25,000 Hz. Moreover, there is another important difference - in the case of non-contact energy transfer, the two windings are not coupled by a ferromagnetic ring which "guides" the magnetic field, but are separated by an air gap. In this way, energy can be transmitted over long paths or in spaces with a mechanical play of just centimeters in a user friendly fashion. The medium frequency ensures high efficiency.Communication between the control computer and the intelligent vehicles takes place via a cable equipped with slots - a so-called leaky feeder - and an antenna installed on the vehicle. A number of independently powered transport vehicles can be securely provided with information, for example, regarding destinations, operating states, or diagnostics. Using this information, the transport vehicle proceeds automatically to its assigned destination. It is totally independent of electrical connections for the receipt of commands or energy. Data transfer rates of up to 4 megabaud can be achieved with this system. Advantages of the new technology are the short distance of a few centimeters between conductor and antenna, and the robust and inexpensive construction.
Non-contact transmission elements, converter technology and automation systems are being integrated into total system solutions. There are appreciable advantages for producers and users of this innovative system technology. Costs are reduced due to the elimination of installation and maintenance expenses, and plant systems are standardized to a high degree. In addition, flexibility can be appreciably increased. Last, but not least, through optimal energy input, reduced noise emission, and elimination of friction these systems are also attractive from an ecological point of view.
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© 1995 Daimler-Benz