ANTI-SWAY/COLLISION AVOIDANCE | TECHNOLOGY REPORT
QR Safe crane operation using IEC 61131-3 programming placed inside ABB drives.
It claims safe crane operation and control
can now be simplified by using flexible IEC 61131-3 programming and certified safety functions placed inside the drives. “We always try to offer our customers
a variety of choices, without locking them into one singular solution. For example, they can choose a drive-based control with our software, or they can use their own programming software, or they can use an external PLC. ABB offers a wide selection of flexibility, but it is all built on standardized ABB configurations and IEC 61131-3 based application programming software for easy compatibility,” says Mikael Holmberg, segment sales manager, Cranes and Marine Winches, ABB Drives. Remote supervision is a growing trend in the industry, according to ABB and allows the crane drives and PLC to be connected for possible remote support and diagnostics. Ethernet-based modules are available for this purpose. In addition, its ACS880 drives include a memory unit for quick replacement or updating without the need of a PC. Holmberg adds, overhead cranes need to
be carefully designed to operate efficiently and safely, whether they are moving containers, buckets of liquid metal, rolls of paper or waste. Every detail matters when selecting crane control for hoist, trolley and long travel movements. ABB’s ACS880 industrial drives with built in crane control software have a range of safety functions to achieve excellent crane performance. For example, load sway can occur in
trolley and long travel movements. The ACS880 drive’s anti-sway control program automatically compensates for it when it happens. The control program creates a mathematical model of the crane’s
40 | April 2021 |
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pendulum. It estimates the pendulum’s time constant by continually measuring the hoist position and load properties, and then factors in the swing velocity and angle. When the operator changes the speed of the crane’s travel, the drive instantly recalculates the required speed reference to compensate for the crane’s speed change, preventing the load from swaying. OEMs have historically achieved crane
control by custom-made programming via a PLC. However, this approach means that the OEM must essentially do everything by themselves which requires high manpower, dedicated in-house skills and continuity over a long time span, often making it very costly. A modern alternative to this approach
is to use ready-made crane applications that provide the necessary crane control via variable speed drives. ABB has recently developed a platform that allows crane control to be done via a variety of routes, all of which utilize the power of the drives. These alternatives include: drive-based crane applications done either by ready- made ABB crane software inside the drives or; do-it-yourself solutions with IEC61131-3 programming inside the drives or; PLC- based control, where the crane application is running in the PLC controller which communicates via gateways with the drive. Here too the programming language is the same IEC61131-3 as in the ACS880 industrial drives. “Our crane solutions offer a combination
of safety, flexibility and standardization for the crane control market. Certified safety functionality which is delivered via the drives is a big advantage. In addition, ability to use the same IEC programming language, whether the control is going through the drives or a PLC, is an important
benefit giving standardization between the drives and PLC,” says Holmberg. Under all circumstances, the equipment must perform safely and precisely, without any risk of a load drop or swaying. Additional value for indoor crane control is delivered with a dedicated link between drives D2D (drive to drive) for master/ follower configuration, where two or more motors are driving the same gearbox. Sensorless anti-sway control is also now standard on ACS880 crane drives, meaning hook swinging is reduced for greater effective indoor crane use. Both trolley and long travel drives can be used with anti- sway in the x-y directions and load swing compensations can be made at same time for both directions. Software benefits are also realized on
outdoor tower cranes where a new slew- control algorithm ensures that the jib is turning around the boom without oscillation. This feature generates both better safety and productivity on construction work sites.
PRECISE MANIPULATION OF LOADS According to PaR Systems there is an increasing awareness, among those who use heavy duty cranes in industries such as aerospace, automotive, and metal processing, that improving crane safety and productivity is of paramount importance and the degree of crane safety and productivity at a given facility can largely be attributed to the crane operators. The skill with which operators are able to drive a crane directly affects load swing, collisions, efficiency, crane maintenance, and the general safety of plant personnel. Its ExpertOperator (EO) implemented within the Siemens platform, is a hardware module that helps operators of all skill levels drive a crane like an expert, which means even novice crane operators can reduce load swing, position loads more efficiently, avoid collisions, and reduce operator-error- induced maintenance requirements. It uses
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