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Rota Naval Base strives for maximum precision in the positioning of jet turbines |
In collaboration with Omron Electronics Spain, Fluidmec-anica Sur in Spain, a company whose activities focus on the automation of industrial processes, has developed an advanced control system for the overhead traveling crane that moves Harrier jet turbines from the entrance of the workshop bay to the work bed at the naval base in Rota, Spain.
Omron inverters have been successfully implemented in this precision positioning application.
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Traditionally, a start/stop command system was used to move the load. However, because of the roughness of the electromechanical brake used to stop the crane, this method involved a serious lack of precision, mainly in vertical movement and in the positioning of the turbines on the bed.
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To solve this problem, and also to guarantee maximum safety when handling the loads (which average about 2000kg), it became clear that a completely new system was needed. What development staff came up with was a 6 meter high-precision crane designed to work with loads of up to 5 tons. The first stage of the newly developed system controls the crane's speed. Omron Sysdrive inverters (3G3XV and 3G3EV) have been installed on the horizontal and transverse axes (the length and breadth of the bay), making it possible to reduce crane speed gradually, to prevent sudden stops and consequent load swing. Furthermore, speed on the vertical axis, which requires even greater precision is controlled by a Sysdrive 3G3FV inverter, capable of providing 150% nominal torque from a frequency of 0Hz.
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The system's control also allows the installation of an encoder for increased positioning accuracy. Any change in load position is detected immediately, and the motor's mechanical brake is activated automatically. The unit shifters are also independently programmed on the horizontal and transverse axes for increased versatility of movement. The entire operation of the crane is controlled from a central pushbutton station, enabling the operator to track load movement at all times. This system has not only achieved the accuracy Base staff hoped for, but has also enhanced safety and user friendliness.
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Even though the new unit has made great progress in improving operations, load swing is still a problem no matter how slowly the crane moves. To remedy this, the Base is now planning to implement an overhead traveling crane with a fuzzy logic control system in configuration with a C200H Alpha PLC, which would completely eliminate load swing.
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