System Integration Case Study: 5,000 hp Robotic Birds
In December 2010, Resorts World Sentosa, Singapore’s first integrated resort, opened what it calls the world’s largest dancing animatronics show extravaganza at its waterfront on Sentosa Island. The Crane Dance performance was first conceptualized in 2008 by the four-time Emmy Award-winning Production Designer Jeremy Railton. To help achieve his vision, Resorts World contracted the design, assembly, and commissioning of the cranes’ motion control and protection system to ITMation Limited, a Hong Kong control-system integrator, and subsidiary of Birket Engineering, Orlando, Fla.
Railton imagined two mechanical birds that fall in love with each other; their love eventually transforms them into real birds. The 10-min. nighttime show features a series of breathtaking high-speed motions, with many close and overlapping movements, mimicking the birds’ mating ritual. The resulting mega-scale animatronics system consists of two steel crane structures, each weighing 80 tons and standing 100 ft tall. The structures are powered by four giant hydraulic power units totaling nearly 5,000 hp.
The slew base of each bird is powered by two hydraulic motors enabling the 80 tons of steel to rotate at more than 15 degrees per sec. The ankle and hip axes are each powered by twin hydraulic cylinders capable of extending or retracting at speeds of over 300mm per sec. Even the giant LED screen on each bird is positioned by a hydraulic cylinder to synchronize its display angle with the bird’s motion. Last but not least is the bird head, powered by two electric induction motors that power the panning and tilting movements.
Making it work
The challenge presented to Eric Tam of ITMation was to create a programmable system that would allow the two birds to act out together the life-like high-speed motions envisioned by the artist, synchronized with music, lighting, video, pyrotechnics, and water effects. The story would be told daily, in a marine environment near the equator, without appreciable risk of a mechanical or hydraulic failure that could damage the massive machines.
To synchronize the 12 motion axes with audio, video, lighting, and water effects, the Simatic central processing unit CPU 317T was selected for the brain of the motion-control system. The Simatic Integrated Safety line CPU 416F was selected for implementing the crane protection system and housekeeping control of the cooling water pumps, hydraulic system, engine control, and other equipment.
The CPU 317T can control and synchronize up to 32 motion axes and has built-in functions for optimizing hydraulic servo valve performance. The virtual cam disk function also offers great flexibility in defining and fine-tuning the motion profile of each individual axis. Besides motion-control functions, the CPU 317T is also a powerful programmable logic controller (PLC) that handles all the logic and sequence controls associated with the hydraulic and show control system.
During the show, a virtual master axis running in the CPU 317T is synchronized with the time code of the master show control system, which is multi-cast over Ethernet using the user datagram protocol (UDP). The master axis then drives the 12-motion axes through virtual-gear synchronization where speed and direction of each axis is calculated from its respective motion profile represented as cam disks. Using virtual gears and cam disks, all axes of the two birds are able to move like clockwork, producing smoothly choreographed motions.
It’s show time
To protect the two 80-ton birds from colliding with each other at high speed, even in the event of a system failure, the CPU 416F system’s extremely fast processing speed can evaluate feedback signals from redundant and SIL-rated position sensors on each motion axis. The processor compares the feedback values with the reference values contained in a 15,600-point interpolation model derived from the actual baseline model. The safety limit of each axis is set individually and stored in a safety database.
During the show, the master-axis coordinates are sent from the CPU 317T to the CPU 416F in real time, and deterministically, via high-speed Profinet I/O communication service. Upon receiving the master-axis coordinates, the CPU 416F derives the reference coordinates of each of the 12 motion axes from the interpolation model. The actual feedback values and the reference values are compared. If the deviation of the two sets of values is greater than the limits defined in the safety database, the CPU 416F sends a signal to the CPU 317T to stop all motion axes in a controlled manner. Only after a safety timer has lapsed does the CPU 416F send a signal directly to the final-stage isolators to isolate power from the motion actuators.
“The Crane Dance is going to be an iconic and exuberant masterpiece showcasing the mastery of presenting performing arts through the world’s best technology,” said Ms. Andrea Teo, VP of entertainment at Resort World Sentosa. “Developed over 36 months and taking 800,000 man-hours to create and perfect, our biggest challenge was to have these giant steel cranes achieve the gracefulness of their real counterparts in the wild, and I am confident they will not disappoint.”
The Crane Dance extravaganza opened on Christmas day of 2010 and is a free nightly show located at the waterfront of Resorts World Sentosa.
Eric Tam is cofounder of ITMation Ltd, serving the process industries and the themed entertainment industry. ITMation is also a Certified Solution Partner of Siemens Automation.
Eric Tam of Hong Kong obtained his Bachelor of Engineering and Computing degree from Monash University Australia in 1996 and became a PROFIsafe Certified Designer in 2008. Together with his father he founded ITMation Limited in 2000, serving the process industries. In 2007, ITMation began serving the themed entertainment industry through its relationship with Birket Engineering. ITMation Limited is also a Certified Solution Partner of Siemens Automation.
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