The July 2011 issue of Hydraulics and Pneumatics magazine featured an interesting application story about how hydraulics systems were designed and used in the “Spiderman: Turn off the Dark” Broadway musical. The article describes some of the challenges faced by motion systems designers, and how those challenges were solved.
One particularly challenging aspect of the hydraulic motion systems was the requirement that multiple hydraulically driven platforms had to be raised and lowered simultaneously. The motion of the platforms had to be very precisely controlled, making hydraulic component selection critical.
In this case, that meant choosing the correct cylinders, pumps, accumulators, and servovalves. But another, often-overlooked, component of the system is the position sensor used to provide accurate, reliable position feedback to the electronic control system. In this case, the hydraulic cylinders each contained a Balluff Micropulse magnetostrictive linear position transducer. The transducer transmits the actual position of each hydraulic cylinder, allowing precise control of the system. Without reliable, accurate position feedback, even the most carefully designed hydraulic motion control system simply can not do its job.
For more information on position sensors used for hydraulic cylinder feedback, click here.