Motion controls inside Cirque du Soleil’s KÀ
Application Update: Motion control with instantaneous redundancy backup propels the Cirque du Soleil production of KÀ, at the MGM Grand Hotel & Casino, Las Vegas. The production includes a 140-ton stage that rises from below ground level, tilts 180 degrees, and rotates 360, while acrobatic actors fly, flip, dance, climb, fight, fall, and operate puppets while the stage is in various positions from horizontal to vertical.
The Cirque du Soleil production of KÀ at the MGM Grand Hotel & Casino, Las Vegas, has motion controls with instantaneous redundancy backup to propel the a 140-ton stage that rises from below ground level, tilts 180-deg and rotates 360 while acrobatic actors fly, flip, dance, climb, fight, fall, and clown over and around it, still and in motion from horizontal to vertical. The stage has about 30 moves per show and has performed reliably since a 2007 motion control retrofit. See related article, "Poetry in Motion," linked at bottom.
Ian Hall, product and application consulting director, Siemens Industry Inc., Digital Factory Division, explained that Siemens consulted with MGM after the show missed several performances because of lack of system redundancies. Also, brake maintenance was high, with the first system, which also didn't include speed control.
Production, retrofit details
Hall offered the following details about the production and motion control retrofit.
- Cast is more than 300; 80 artists appear on stage; about 80 more work behind the scenes.
- With the stage near vertical, 80 pegs emerge in various locations, using proximity sensors to avoid human contact while emerging or disappearing, synchronized to provide the allusion of warriors fighting on a cliff.
- A projection screen makes the surface a touch sensor for some scenes, reacting with ripples of light to actors' feet and simulating arrow strikes.
- McLaren Engineering did the original design, including hydraulics with 4,000 gallons of vegetable oil (now mineral oil is used).
- The platform moves 70 ft at 2 ft/sec, using 4 hydraulic cylinders with a 70-ft stroke. Downward speed is limited to 1 ft/sec for safety. Five 250 hp pumps feed the piston accumulators that produce 6,000 hp. The pumps, running at 1,500 psi, and accumulators are about 1000 m away from the stage, feeding the hydraulic cylinders via pipes at 770 psi pressure.
- The original design had perhaps 30 single points of failure, including encoders and controllers. Brake maintenance was high, since brakes were used at every stop, about 30 per show, two shows per day. Move commands required 16 seconds of lead time because brakes had to disengage and pumps had to increase pressure. Left to right balance wasn't always stable. Several shows were lost from system failure using the first design. More redundancy was needed.
- The automation vendor provided project management and engineering support for the retrofit and motion system upgrade, over a year and a half, with most work during schedule shutdowns. Study began in 2005. In 2007 the solution was implemented and the production had two control systems until the new one was ready, tested, and approved.
- New system has only one or two single points of failure (including hydraulic servo control valves).
- The motion controller voting system uses a plausibility test for each move to ensure controllers agree that a move should be made.
- In the new design, brakes are only engaged once. Hydraulic pressure control maintains position control, keeping the stage in position design actors' weight and action.
- Instead of a 16-second cycle, closed-loop position control provides a response rate measured in milliseconds.
- A Profibus network is used for motion control; an Ethernet network mirrors communications and serves as a backup. Profibus is represented by PI North America.
- Smoothness of ride was notable after national frequency of the stage and non-linear nature of the application were taken into account by applying filtering and tuning optimization. (Taller column of fluid created more bounce.)
- Programmed speed override is possible if a timing adjustment is needed. Full reset takes 20 seconds and left to right balance is within one-half inch.
- Mark T. Hoske, content manager, CFE Media, Control Engineering, firstname.lastname@example.org.
- A retrofit motion control project to create instantaneous redundancy backups for the Cirque du Soleil production of KÀ, at the MGM Grand Hotel & Casino, Las Vegas, has performed reliably since its 2007 installation.
- The production includes a 140-ton stage that rises from below ground level, tilts 180 degrees, and rotates 360 degrees.
- The automation vendor served as the primary contractor on the retrofit project.
How could a motion control retrofit provide greater reliability through redundancy, smoother movements, and precise position control to an existing application?
Siemens' 2015 Automation Summit — A User Conference in Las Vegas starts Monday night. Learn more about the event.
www.us.profinet.com (PI North America)
Siemens has a PDF about the motion control retrofit for MGM Grand's Cirque du Soleil production of KÀ.
For more details about Cirque du Soleil production of KÀ and motion control used at MGM Grand, see the 2007 Control Engineering article, "Poetry in Motion," linked below.