ANTI-SWAY
PAR EXPERTOPERATOR
Passive anti-sway systems are often described as having no sensors. To be strictly accurate, they typically include one component that could be considered a sensor: the device that measures the length of rope paid out. This measurement is essential because rope length directly affects the sway frequency of a suspended load. For any given load and rope length, there
are multiple ways to move it from point A to point B without sway. One option is to travel at a very slow, constant speed – an approach that will always work, but is tedious and inefficient. Another is to accelerate quickly, then decelerate the trolley to counteract the sway, and finally reverse the process to stop. In fact, there are an infinite number of such carefully timed procedures that can achieve sway-free motion. There is, however, one system on the market that avoids the need for these procedures
altogether. Unlike conventional passive systems, the ExpertOperator anti-sway system from PAR uses no sensors whatsoever – not even rope-length feedback – and requires no operator input, such as rigging length or tuning, beyond initial setup. Instead, it transforms the operator’s raw crane commands into ‘expert’ commands. Unlike most other passive systems on the market, which use rope length to attenuate a single frequency, ExpertOperator’s core algorithm attenuates sway regardless of frequency, meaning it adapts automatically to any rope length. The result, according to PAR, is a system that delivers exceptional performance at low cost with minimal setup. Importantly, it remains a passive system – it does not actively compensate for wind loads, off-vertical lifting or sway introduced by riggers. But it is unique in being a truly sensorless anti-sway solution.
minimum or completely turn it off. So, you really have a system that appeals to the majority. “Speed is an advantage, especially in
semi-automated and fully automated cranes. There are of course mechanical and electrical restrictions, but especially in a closed-loop system the crane knows exactly where it’s going and automatically eliminates the sway along the way to its position.” And there are some benefits that are less immediately apparent. Anti-sway can give more accurate positioning of set-down, down to millimetre-level if required. It also gives
longer lifetime to your lifting machinery. “The number of start-stops and control alterations in each lift is much less than under operator control – that, and the fact that there is no sway in the system also reduces the mechanical stress on the system.”
Collison avoidance is another digital-led
technology that, in fact, pre-dates sway control but can be integrated with it into a single crane- control system. It does, though, require another set of sensors.
“Collision avoidance has been out for some 30 years or more and is generally used to keep
cranes that are operating on a shared runway apart, or to create a zone where the crane is not permitted to operate,” says Childers. “And what you need to avoid collisions is some way of knowing how far away the object you might collide with is. At R&M Materials Handling, we offer multiple types of collision avoidance sensors, and the type used will depend on the environment where the crane is installed. Collison avoidance can be provided for cranes with or without sway control. Collison avoidance is a key feature for customers looking to increase operation efficiency and reduce the risk of an incident caused by a crane or load striking a machine or structure.
“R&M has combined both collision avoidance and sway control technology into the crane package offerings. At the heart of the system is fieldbus technology,” he adds. “In the past each of those commands – of anti-sway, of anti-collision, of overload protection and the like – were sent on individual wires, with one set of wires for each function and virtually no data sharing between devices. Fieldbus simplifies all of that: a single four-wire cable connects all the electrical controls together and to the HoistMonitor Enclave which is the brain of the system.
Sway control, as utilised here by Siemens, helps protect delicate loads. 24 | October 2025 |
www.hoistmagazine.com
“And the huge advantage that it gives is that it allows all the commands to be sent very quickly over a network, creating one communication system that allows each device to communicate with all other devices that enable the sway control and other operator assist features. The sum of the parts is
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