At the heart of digitalisation is data—its gathering, storage and analysis, in sometimes vast quantities. Thus, for example, the SMC multicontroller from Stahl records the complete operating data of a hoist, and can transmit it wirelessly to a global server so that it can be accessed from anywhere in the world in real time. The remaining service life of the hoist can be calculated, taking loads, speeds and running times into account. Efficient preventative maintenance can be scheduled, reducing unplanned downtime. Everything about that hoist can be known, and known from anywhere.
Only a decade ago all that would have seemed fantasy. It is now standard and routine. But if digitalisation has brought us on a rapid journey, hold on to your seats. You have seen nothing yet.
We are, it seems, on the very edge of transformation. The next stage in digitalisation is not just control of a hoist, or even of all the hoists in a plant or factory together.
To begin then, at the current state of the art. Consider process cranes, which carry out the same repetitive task many hundreds or thousands of time. That is easy to automate. A sensor switch to tell when the trolley is at the end of the runway, a relay or two to then open the grab, and your load of raw material is dumped in the right place and the trolley can return, automatically, to where it came from for the next load. Add more relays as required to give more functions.
“There used to be a lot of relays in overhead cranes,” says Chris Russell, technical director of Street Crane. “Most cranes now have a PLC on board. The most basic system on a product has sensors on the crane that activate warning lights, and the operator obeys them. So for zoning control you have infra-red sensors measuring distances, or for greater distances, you would use ultrasonic sensors.
“A lot of microprocessor controls are being built-in to hoists, but they are not yet universal. Many operators, in harsh or remote environments, want reliability and real ease of maintenance rather than sophistication. Customers in Northern Canada or the Middle East want plug-in units that do not need an expert to repair them. Users in high temperatures also, such as foundries, are wary of relying on microprocessors.
“But as sensors and processors become more reliable and less costly that is changing. For example, anti-sway is a standard in all manufacturers’ arsenals now. So is inverter control for trolley travel; but it is not yet standard for the hoisting drum. One reason for that is the size of the inverters, but they are shrinking. Within the next five years inverters in hoisting mechanisms will be standard across all manufacturers and if you want one without it will cost you more, because it will be non-standard and you will have lost the economies of scale.
“There is more and more safety monitoring of crane equipment using digital technology. An example is digital rope inspection. At present, equipment is carried around by specialists who come and check your wire ropes for internal flaws for you. Soon the equipment will be smaller, cheaper and fitted as standard to every hoist, and it will check the condition of your rope every time it is used and will display that data on your smart-phone. That is just a matter of time.
“But safety monitoring still relies on how good your sensors are,” he says. “You need sensors to be solidly reliable; and you also need them to be cost-effective in the market-place. A lot of futuristic things are possible. At present, they all cost, but are available if the customer wants it. But the marketplace is moving at a fair pace. People are wanting more, and expectations and standards are creeping up.”
Stefan Elspass is in charge of product management at Demag. For him, the modern era has its roots around the year 2015. “That was when we began to start communicating to audiences, explaining what Industry 4.0 could do,” he says.
That was just four years back. “Since then, we have been able to communicate the abstract possibilities. What we need now is to make real products and real business models.”
Key to this, he says, is the availability of technical enablers: not only the sensors themselves but the ability to communicate wirelessly, seamlessly and reliably one with another, the ability to feed data to remote monitoring, and to allow decentralised control. “Control systems have not been strong enough for the long term,” he says. But the tipping point has come. “Now is the time that Industry 3.0 is changing to Industry 4.0.”
The difference, he says, is that before, under Industry 3.0, machines were under individual central control—that is, the crane was controlled by the crane operator or by some digital system whose job and whose focus was centred around that crane. “Industry 4.0 is about decentralised control,” he says. The crane or hoist is just one part of a system of dozens, perhaps hundreds, of other machines, every one of them able to communicate with the others, all operating collectively, and all focussed on a common end.
Demag, he says, was in at the beginning of this. “We produced the first computercontrolled hoist in 2003. That was a big change in the market. We came in then with embedded controls, that could give such things as speed control. Our Safecontrol system has some decentralised aspects. The hardware drive is in a central crane cabinet that can communicate with several different cranes; it is a first step, but decentralised control means much more that this: it is the intercompatibility of the system with different kinds of hardware from different manufacturers and suppliers.
“In the past we lived in our own crane world with its own control system. Now we must make sure that our systems are enabled to operate with other machines of other kinds from other suppliers.” As a simple example, a gantry crane may be fed or may feed its load to a forklift truck. Crane and forklift need to work together; they need to talk.
“For that to happen, it needs wireless communication as a reliable, safe and capable core competence,” he says. “That means communication interfaces that are standardised right across industry.” There is such a protocol: it is called OPC Unified Architecture, or OPC UA. “Adoption of OPC UA is a precondition before Industry 4.0 can happen,” says Elspass. When every hoist maker, every forklift maker, every maker of every other machine used in a factory adopts it, the entire plant becomes, in effect, a single unit.
Digitalisation in hoist technology has brought us such things
