It is possible that one day cars will fly, or that they will slide without contact on the ground generating a magnetic field that is repelled by the large magnet earth (would there be cars for the northern hemisphere and for the south? … they would surely have a “polarity change” switch. But what do you say? They would use GPS location to switch polarities) … mental speculations, I will say, avoiding the colloquial.
There are many advances in this regard, but in the meantime, they move using circular shaped pieces invented thousands of years ago.
I will try to make sense of this seemingly disjointed introduction later.
The automation of product packaging is undoubtedly one of the fields of application of robotics in general, and one of the variants is the use of collaborative robots.
From PROBOTEC we have understood this, and the result is our “PalPro“, a complete and simple solution based on robust fundamentals.
We will make a brief tour of some of the bridges that we have been crossing.
Distribution of elements – Mosaics
One of the tasks to be performed prior to palletizing is to determine the placement of the elements on the pallet, based, mainly, on the optimization of the final volume, although there are other aspects to take into account such as the stability of the whole. To do this, it is usual to distribute the elements in alternately different layers and optionally, to intersperse between them some separator element. What is the optimal placement?
Container packaging is an optimization problem, in which items of different sizes must be located in a finite number of containers, each of a fixed capacity, so that the number of them to be used is minimized.
Computationally speaking, the problem is of the NP-Hard type, and the corresponding decision problem (deciding whether the elements can fit in a specific number of containers) is NP-complete.
Despite its difficulty, in the worst case, optimal solutions can be produced for very large instances with sophisticated algorithms. Many approximation algorithms are existen. For example, the first adjustment algorithm provides a quick, but often not optimal, solution that involves placing each item in the first space in which it fits. It requires Θ (n log n) times, where n is the number of articles to pack. The algorithm can be made much more effective by first sorting the list of items in decreasing order (sometimes known as the decreasing algorithm of first setting), although this still does not guarantee an optimal solution, and for longer lists it can increase the execution time of the algorithm. It is known, however, that there is always at least one ordering of elements that allows the first adjustment to produce an optimal solution.
There are many variations of this problem, such as 2D packaging, linear packaging, weight packing, cost packaging, etc.
A variant of containerized packaging that occurs in practice is when items can share space when packed in a container. Specifically, a set of items might take up less space when packed together than the sum of their individual sizes. This variant is known as VM packaging, because when virtual machines (VMs) are packaged on a server, their total memory requirement could decrease due to pages shared by VMs that only need to be stored once. If items can share space arbitrarily, the problem of containerized packaging is difficult to even approximate. However, if the shared space fits into a hierarchy, as is the case with shared memory in virtual machines, the problem of containerized packaging can be approached efficiently.
PalPro facilitates the configuration of tiles by offering different distributions of elements per layer to choose from.
Optimized hardware architecture – PalProPC+HMI
Although the programming console of a robot, or a conventional HMI, can be used as an interface for the configuration of tiles (enter box measurements, edit layer distribution, select stacking order, etc. ) there is no doubt that this task is more typical of a personal computer, with the convenience of using a conventional mouse and keyboard. PalPro has a PC with touch screen that fulfills a double function: Create and edit the different distributions and HMI interface for the exploitation of the cell. (Running the configuration software PlaPro can be performed on any other PC, in the office, e.g. and then transfer the result to the cell)
Once the Job to be performed has been selected, the necessary information is transferred to the PLC that takes control and is responsible for indicating to the robot the trajectories to be executed at all times: From where and what element it has to take, and where it must deposit it.
From that moment on, the PC goes on to fulfill the functions of HMI as mentioned above.
PalPro, a round solution
I admit that we have not invented the wheel (because it was already …) but we have eliminated any quadrature atisbo, optimizing resources, without using cannons and we have a proprietary, scalable and 100% solution under our control.
Manuel Juíz, Product Development PROBOTEC.
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