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Video: Avoid Accidents
In extreme situations, modern work platforms have sophisticated systems to avoid accidents. But are they as intelligent as they promise or do they also harbor dangers? We illuminate some assistance systems and show what they can and cannot do.
The most reliable are working platforms that determine in real time which loads act on which component. If, for example, a device has sensors for determining the load distribution on all supports, the change in the support load is determined directly with every movement of the jib. The center of gravity of the machine is then determined from these values - as long as this and the jib are not on the same side of the tilt axis, the working platform will not fall over. The intelligent software also includes a safety buffer so that swinging the basket does not lead to an accident. Unevenness of the surface is included in the calculations in connection with a position sensor - so stability is also guaranteed for sloping stands.
A system in which the maximum display for each angle of attack is stored in the software is one step simpler, but no less secure. The load is not permanently monitored, but a sufficiently large safety buffer is programmed, which also compensates for a slight gradient in the ground, vibrations of the basket arm or wind.
A basket scale prevents people, tools and materials from exceeding the maximum basket load. Here, too, there are different systems: the simple ones warn the user with an optical or acoustic signal, the more sophisticated systems completely prevent the use of the device with an overloaded basket.
What the systems do
Once a potential hazard has been identified, humans or machines have to decide how to react. Both approaches have advantages and disadvantages. A human decision maker can still make mistakes knowing that his actions are dangerous. However, an experienced operator and his assessment of the situation, which is not only based on a large number of sensors and wires, are an advantage that should not be underestimated. One possible reaction to a situation recognized as dangerous is the emergency shutdown: Suddenly nothing goes from above! All movements that are still to be carried out must be controlled from the ground (i.e. on the control panel of the chassis). The deterrent effect exists, but at the same time it also harbors a potential hazard from the assistance system. Because:If the operator is alone on the construction site or if the people present are not familiar with the operation of work platforms, there can be an involuntary break.
The idea is simple: only movements that reduce the load on the cage arm are permitted. But what is a load-reducing movement? Who determines whether the load is actually successfully reduced? If an obstacle is exactly in the direction in which the arm is telescoped in, an accident is inevitable. If the jib is rotated, the center of gravity of the machine changes (with constant load), which can favor an accident as well as an increase in the load. Even the idea of driving back the same way that brought the basket to the border can pose a risk. The path could now be blocked. What sounds good in theory is difficult to implement in practice. The dangers that could lurk are too diverse, the information situation of the system is too imperfect. Nevertheless, a collision with a tree, for example, is less painful, i.e. a fall from a height.
So there are always dangers where technology does not have the environmental information that a person can perceive. Isn't it enough to make people aware of the danger and leave the solution to the situation to them? Many devices do this by emitting visual or acoustic warning signals. Sure, the beeping is annoying, but ultimately prevents anyone from putting devices in situations for which they are simply not designed. However, the attentive high-altitude worker becomes sensitive when he realizes that he is putting his work tool in an extreme situation and reacts with suitable movements of the jib.
Before the employee is on stage for the first time, he should be trained theoretically. With the PAL-Card, the International Powered Access Federation (IPAF) offers a certificate that meets the highest quality standards and is recognized worldwide. IPAF has various training centers in Germany, and many partner lift companies are recognized training centers.
It can therefore be said that the danger posed by working with aerial work platforms cannot be completely eliminated. In addition to the fact that external influences such as storms and thunderstorms cannot be hidden, there is always a residual risk that results from human weakness and the incomplete data situation of a computer, even if the assistance systems are getting better and are believed to save many lives and injuries have prevented. The assistance systems currently available are mature and do their job. But that does not relieve anyone from acting prudently and thinking with them at all times!