IS IT MATH, INSIGHT OR MAGIC?
Industrial cranes are everywhere. They come in all shapes and sizes, and serve a wide variety of industrial purposes. From monstrous 500T production cranes to small 3T maintenance cranes. Yet they all have one thing in common. Their loads sway.
Sway is a direct consequence of Newton's First Law: "A body at rest tends to stay at rest; a body in motion tends to stay in motion." When a crane picks a load and starts to move, the load lags behind, trying to act as a body at rest. When a crane reaches its destination and starts to stop, the load keeps going, acting as a body in motion. The sway frequency is determined by the distance between the hoist and the load. The greater the distance, the greater the sway. The greater the sway, the longer it takes for the load to settle. And the longer it takes for the load to settle, the greater the danger to surrounding equipment and personnel.
In its simplest form, sway in cranes is a product of the speed
of the crane and the length of the cable. The faster the crane
accelerates, the more prominent the sway. The longer the
cable, the lower the frequency, but the greater the amplitude
of the sway. Ironically, the weight of the hook or the load
has little effect on amplitude or frequency, although it definitely
adds to the momentum of the load in the event of a collision.
And similar to rigging, the load itself can introduce secondary
oscillation. Any pivot point in the extension from the hoist to
the center of gravity of the load introduces another oscillation
or sway frequency that must be addressed to effectively
manage the overall sway of the load.
In the real world, however, cranes are about more than cables and hooks. Cranes often employ rigging to secure the load. Rigging enables cranes to transfer a variety of loads, each with it own unique dynamics. These dynamics need to be accounted for when compensating for sway. In effect, rigging is a secondary pendulum that introduces a secondary or compounding frequency to the dynamic.
Most anti-sway products on the market today do not automatically account for secondary oscillation. They depend on expensive sensors, including encoders and/or cameras, to measure the cable length, and they rely on operators to input real time rigging and load data, which more often than not doesn't happen. More fundamentally, however, even if the data is uploaded, the algorithms employed by most of our competitors only approximate the real world dynamics of cranes, their load and their rigging. They do not accurately account for the dynamics of secondary and/or tertiary oscillation.
InVekTek's algorithms do. Over his many years of research and development work for NASA, the Defense Department, Boeing, Caterpillar, Alcoa and many others, Dr. Singhose has developed a deep understanding of the fundamental nature of machine dynamics and unwanted motion. InVekTek employs Singhose's refined algorithms, as well as sophisticated proprietary software, to automatically avoid sway in cranes, regardless of configuration. We call it Sway Master™. We don't need sensors or encoders or cameras. We don't need operator input. We simply configure the system at the time of install, and our algorithms do the rest.
Call is math, insight, or magic, InVekTek's Sway Master™ is truly disruptive. Cranes employing Sway Master™ run faster, smoother, safer, with less maintenance and greater energy efficiency, all at a lower installed cost.