Explain it to me.
There are three basic considerations in designing an effective ADS joint. First, there’s the movement geometry: the joint must be able to rock, flex, rotate or slide with the least friction possible. The less friction, the easier it is to move. Part of the friction is caused by the pressure seals (think of a swivel O-ring), which must keep out water and pressure. Finally, there must be a means, for example, with a bearing, to transfer the “pressure” load between the two ends of the joint with minimal friction so that they can move. Remember the water pressure is acting to telescope the limb back into the suit. Transferring that load with minimal friction is the key.
The basic idea is pretty simple. Let’s use your foot as an example. Try to spin with one foot planted flatly on the floor. It’s difficult. Your foot must transfer the load (your weight) from you to the floor while you are turning. Now tilt up on one heel. You can turn easily. The area of contact, and therefore, the friction, has been greatly reduced even though the point load has increased in direct proportion. Turn on a hard wood floor and it’s even easier, unless you were to add a lot more weight. That’s how ball and roller bearings work; they are very hard surfaces with high point loads. Unfortunately, as you increase the load, the friction on the ball or rollers increases as well until they eventually embed themselves into the turning surfaces and stop.
The problem in ADS is that the loads exerted on the limbs by the pressure are extremely high. That’s why mechanical bearings only work at very modest depths. For example, at 1000 feet/307 m there is almost 500 pounds per square inch on a wrist joint which has a surface area of about 25 square inches. If you do the simple math, you realize that the end load pressure on the joint is roughly equivalent to having a London double-decker bus standing on top of a bearing [25 sq. in. X 500 psi = a load of 12,500 psi –ed.] There’s not a bearing made that will tolerate that kind of load in that small an area. So you have to find means to handle the load, transfer it through the limb back to the fixed point, in this case the suit, and have it move easily enough to be driven by muscle power. Designing the bearings and seals to transfer high loads at low friction is one of the most difficult problems in ADS design.
Photo courtesy of Phil Nuytten.
How did you solve it?
The major break-through in the NEWTSUIT consists of two parts: a bearing that is not a bearing, and a pressure seal that sees virtually no pressure. The bearing transfers the load through a fluid. Conceptually, the joint is made pressure-tight by two spring-loaded seals floating freely on a cushion of oil that is perfectly balanced against the external pressure. To move the joint you sheer the fluid. As you know from high school physics, a dense fluid, such as oil, is practically incompressible. Any load applied to it is simply transferred through from one side to the other. No matter how much pressure is applied, the whole mechanism is held static. It can move freely with minimum friction. The moving seal doesn’t know it’s under pressure because it has the same pressure above and below it. There is a static seal that does see a pressure differential, but it does not have to rotate. The result is a seal that is automatically pressure-balanced. It is under tremendous pressure but it is completely equalized. That is the basis of our series of international patents. It’s a principal patent, not an application patent. As far as we’re able to determine the principle has never been utilized before. It’s that basic.
What’s more is that the whole mechanism is a “fail-safe” design. Any failure in the seal means that the oil serving as the bearing will leak into the sea or into the suit and will no longer hold the sealing surfaces apart. The result is that the entire joint will lock up tighter than a bull’s ass in a windstorm. The joint will be totally immobilized but will not leak a drop. The fail-safe joint is similar to the “dead-man” switch on your diver propulsion vehicle. If your finger fails, the system itself shuts down.
I’ve read “Ironman” [Marvel Comics] since I was a kid – the notion of flying around in a do-all/be-all power suit has obviously been around for a long time. Is that the direction the technology is going to go?
Oh, yeah. The things of comic books and science fiction are going to come to life, particularly in the next generation suits. I think you’re going to see a situation where the suit will become all important. It’ll be like a violinist’s violin or a pianist’s piano. You won’t be able to operate without it. It’ll be your armor, your protection. It’s where you like to be. It’ll be how you see, how you walk, how you move. It will mean everything to you. I think that’s going to make for some pretty interesting neurosis down the road.
“Tony Stark” [Ironman] has certain had his fair share. What are the technical barriers to a power-assisted suit? Is the technology here?
No. The problem is one of control, and boy, we have looked hard at it and so has the National Aeronautics and Space Administration (NASA). Remember, the NEWTSUIT arm is a hollow conduit. It can’t describe the arcs of motion that a typical manipulator can do or it would cut your arm off. Anything that is strong enough to assist you will also be very detrimental to your meat if it gets away. That’s a real concern.
Are the robotics people, like Schilling, working on that kind of stuff?
No, they’re not because they’re not working on hollow conduits. Interestingly enough, the General Electric Company developed a whole series of semi-cybernetic devices called “Handyman” and “Man-Mate” about 20 years ago. The Man-Mate Division went on to develop the walking front-end loader—the exo-skeleton that was used in “Alien 3″. It was based on the G. E. Arm, a very fine device, which was a spatially-correspondent, tactile feedback manipulator. Spatial correspondence means that when you moved the master unit that you held in your hand, the corresponding slave manipulator moved proportionately to your movement. It could even sense weight. For instance, you could pick up something with the arm and you feel the weight on the master; you could set it so it would be 1 to 1, 1 to 10, whatever you wanted, an absolutely marvelous device. I believe Western Space and Marine, out in Santa Barbara, is working with them now.