The main driving force for the developers of the Zollner Elektronik AG was to produce a radio remote-controlled, four-legged walking robot of an unprecedented size being suitable for outdoor use. Also the fact that this mechatronic system should become the leading actor in Germany’s longest running folk play motivated the team extremely.
Zollner Elektronik, Zandt (Germany)
The result is a fully functional walking robot with a length of 15.50 meters, a width of 3.80 meters, a height of 4.50 meters and a total weight of 11 tons, powered by a 2.0 litre turbo diesel engine with 140 HP – a mechanical performance of 80 kW and an electrical power of 10kW which beats any human actor. Two hydraulic circuits, a high pressure of 220 bar and a low pressure of 80 bar, 272 hydraulic valves, 65 moving axes and 238 sensors connected by means of 300 meters of hydraulic lines, 1300 meters of electrical lines as well as 110 meters of pneumatic lines underline the size of this complex mechatronic system. In order to ensure a rapid transport of the walking robot from A to B, a special transport vehicle was designed by the company.
Realization of the project
In February 2007, the major project ‚Tradinno’ – a synthesis of the words Tradition and Innovation – started with the verification of the concept. The standard DIN EN 61508 “Functional safety of electrical systems”, which accompanied the whole design process up to the approval, required a SIL 3 classification (safety integrity level) for special functions.
At the beginning of the project, detailed calculations and simulations had to be made. Multi-Body Simulations by means of Simpack mapped the various, dynamic movements. Durability prediction, strength simulations and temperature simulations as well as comprehensive tolerance analyses supported the developers in their calculations during the run-up. Planning tool for the whole mechatronic system was the CAD program Pro/E (Pro/Engineer, the electronic-board-layout simulation was made using the software Hyperlinks.
A group of 15 developers, consisting of experts from mechanics, electronics and software departments worked in parallel on the mechanical construction and the design of the load-bearing structure, on the drive and the required drive capacity as well as on the respective control units.
The self-development of hardware and software of nine modular control units is one of the electronic highlights of Tradinno. These units include two processors, a DSP (Digital Signal Processor) from Texas Instruments which is meant for regulation and control as well as a Fujitsu microcontroller for the communication. The FlexRay communication through nine star-shaped nodes, which guarantee redundantly 2 x 10 Mbit per control unit with a sampling rate of 200 microseconds (µs) ensure the LVDS-data transmission (Low Voltage Differential Signalling) and meet all requirements regarding security aspects.
Also the integration of the drives and sensors, which are available in double redundant design, represented major challenges for the electronics development team. Meanwhile, the mechanical design team planned how to meet the mechanical requirements concerning the heavy steel giant. Especially the walk on four legs of the 15.50 m long, 3.80 m broad and 4.50 m high robot caused quite a headache from time to time. The solution with seven degrees of freedom per leg which allow both, curve walks and the parallel offset crab steering, inspired robot-specialists worldwide. The design of the control unit in connection with the mathematical walk algorithm is now patented by the company. In order to enable the walking robot to move lifelike in the folk play, the bidirectional radio transmission is realized via four in-house developed operating units. Also, the 2.0 l turbo diesel all-wheel-driven and all-wheel steered transport vehicle with a weight of 4.3 tons which enables the transportation of the 11.0 tons heavy robot is controlled bi-directionally by a radio remote control with four different steering modes, front axles steering, rear axle steering, articulated steering or crab steering.
Competence network
When realizing Tradinno, the development team used the flexible competence network of the Zollner Group and worked closely together with innovative companies and institutes. The developers equipped the robot body with wings with a span of 12 metres, put it in polyurethane skin and GFK skin, filled the veins with 80 litres of artificial blood and helped Tradinno to become a fire-breather, according to the requirements, by means of 11 kg liquid gas. Meanwhile, the mechatronic system Tradinno has already left the EMS-provider located in Zandt, now bears the name “dragon” and celebrated its premiere in the last year’s “Drachenstich” in Furth i.Wald as main actor.
Zusammenfassung
Insgesamt zwei Jahre tüftelte das Ent- wicklerteam von Zollner an der Drachen- konstruktion, sollte doch ein funkgesteuerter vierbeiniger Outdoor-fähiger Schreitroboter in noch nie dagewesenen Dimensionen realisiert werden.
Au bilan, c’est pendant deux années que l’équipe de développeurs de Zollner a bricolé à la construction du dragon qui devait être réalisé sous la forme d’un robot articulé à quatre pattes, télécommandé et capable de séjourner en extérieur, le tout dans des dimensions encore jamais atteintes.
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