What is in this article?:
- Powering the world's largest motion platform
- Meeting high expectations
The challenges of moving a 60-ton, full-size replica of a sailing ship for one of Hollywood's latest movies are explored.
Meeting high expectations
Since special effects have become a major segment of today's action movies, high expectations have been placed not only on equipment performance, but also on reliability. Once the film crew, special effects experts, actors, stunt men, and everyone else involved in a particular scene have assembled for a shoot, everything must work as planned. If anything doesn't, the lost production time can cost thousands of dollars per minute.
Dan Sudick, special effects coordinator at Commander Productions, considered the size of the mechanical system and complexity of controls, and mapped out many potential plans to operate the Surprise replica. Hydraulics were the clear choice for actuation because they could handle the dynamics of the application without question. The need for closed-loop motion control was also obvious because of the tight motion and position control requirements. The challenge was to provide an integrated system that could generate the power required to move the tremendous load through a wide range of motions and have everything look realistic.
But even though tight control was required, the resulting motion could not appear to be jerky or stiff. Fluidic motion was especially important for this application because a ship at sea pitches, heaves, and rolls smoothly. The only time a ship would jerk or move suddenly would be if it ran aground. So motion had to be highly damped to avoid any sudden movements.
Another challenge was the variable load presented by this giant stage prop. Buoyancy forces from the water caused the Surprise replica to become "lighter" as it became partially submerged. With a reduced load, the hydraulics could become too stiff, potentially creating unrealistic motion. This meant the system had to self-compensate for varying load conditions.
The system was installed as it had been designed, but the expectations of the electrohydraulic servo control became higher than had been anticipated. This led Sudick to look for specialists in hydraulic controls. He chose Delta Computer Systems, Battle Ground, Wash. to help with this concern.
After the first run of the original system, the special effects people were skeptical as to whether the system would be controllable enough to meet their needs. They had to be convinced, and it needed to happen quickly because the shoot was scheduled to begin only a few weeks after the entire system had been installed.
Because Delta manufactures motion controllers designed for the special needs of hydraulics, they convinced Sudick that they understood the requirements of the hydraulic controls and had the solution.
Time was running short, so Delta suggested using a proven control systems integration company to integrate the motion controls. That is when Concept Systems Inc. entered the project.
An alternative solution
Michael Gurney, a founder and principal engineer at Concept Systems, went to the site immediately after the decision was made to go with Delta and installed and wired an RMC100 motion controller into the system. He then tuned the system, ran the motion program, and had the system running within six hours. This was unprecedented for a project of this stature.
Because Concept Systems was not brought into the project until it was nearly completed, very little time was available for testing. Nevertheless, Gurney had the ship rocking and rolling in two days, with less than ten hours to test it. This all was possible because of Concept Systems' extensive experience implementing challenging motion control solutions under demanding conditions.
To produce smooth motion of the platform, the RMC100 advanced tool was used set to run third-order cubic splines. This programming feature automatically sets optimum acceleration, deceleration and velocity based on simple operator commands. It accomplishes the same effect as variable damping of the system. But damping the system would have required re-engineering the hydraulic system, which was not an option. To simplify operation, Concept Systems added a PC-based operator interface, allowing for simple button-type interaction with the motion controller. This provided the look and feel the special effects crew was familiar with.
Dan Sudick was impressed with the whole system Concept Systems installed, especially the motion controllers. "The RMC100 controller is the best we've ever had," he offered. He added, "We can use this on many special effects requirements in other productions."
For more information, call Concept Systems at (866) 791-8140 or visit www.conceptsystemsinc.com.
After this article was originally published, a subscriber wrote with additional information. His comments, and a response from the article's author, are shown below.
Give credit where it’s due
Upon receiving the July issue of Hydraulics & Pneumatics , I was initially very excited. But upon completing the article about the upcoming movie, Master and Commander: Far Side of the World, I was very disappointed. The article gives Bosch Rexroth credit for work they did not perform. Specifically, author Johanson wrote, “Bosch Rexroth also supplied the massive hydraulic power units, valves and other hydraulic components including runs of more than 250 ft of hydraulic lines.”
To clarify, GS-Hydro supplied 12 runs of more than 250 ft of hydraulic lines and many valves. We are very disappointed that this article was allowed to be printed without involvement from all of the major contributors.
How the hydraulic fluid was transported from the hydraulic power units to the gimbel was a major concern for Fox Motion Pictures on this project. The special effects coordinator did not want a repeat of the type of problems the studio had experienced filming Titanic .
I personally spent three days in Rosarito, Mexico with our project manager, Peter Laneri, working with Dan Sudick and Ralph Kerr. GS-Hydro’s design manager, Scotty Bearb, 3-D modeled a non-welded piping system that spanned a total of 4500 ft. The entire piping system was prefabricated in Connecticut and installed in Mexico in three weeks from time of order.
I, for one, will be at the movie theater November 14th watching the boat rock and roll, and I hope that by then I won’t be the only one who knows that it takes many great products, people, and ideas to make hydraulic special effects electrify an audience.
Scott Cady, president, GS-Hydro U.S. Inc. Bloomfield, Conn.
Author Johansen acknowledged that the hundreds of feet of piping were, indeed, provided by GS Hydro. He brought this to our attention after initial approval of the manuscript, but the issue had already gone to press.