Details of the DRZ Living Lab
The heart of the DRZ is the Living Lab and there are many individual highlights. What makes our experimental hall with adjoining outdoor area so special is presented below on a more detailed level.
First of all, we would like to start with the place where a lot of things were created for the Living Lab: the workshop.
Basically, the title already says what this area is for. In the workshop there is the possibility to carry out various work - starting with the realisation of new constructions up to work on the robots.
The workshop is equipped with tools from KS Tools, Metabo or Kraftwerk. Furthermore, machines have been lent or donated to the DRZ, such as the welding machine, the drill press or our massive welding table. These machines enable us to saw material exactly to size or to drill recesses with our pillar drilling machine and also to weld metal components together. Although many things are made of metal, our hall master prefers to build structures such as the DRZ Challenge out of wood. Because of this, the Living Lab is also well equipped for woodwork. The workshop offers everything from a cross-cut saw with adjustable angle to a classic foxtail saw and a chisel, all of which is necessary for such work.
However, because something sometimes needs to be soldered quickly while experiments are being carried out, the workshop also has a soldering station. At the soldering work table, circuit boards can be soldered or other soldering work can be carried out professionally at any time.
So you see, at the DRZ Living Lab nothing is left to chance and we are equipped to carry out any work with the utmost precision.
The 3D printer that is part of the DRZ's equipment is called the Ultimaker S5. It prints the components by building up the plastic layer by layer. This type of printing is called fused layer modelling. The layers laid on top of each other in this way are usually between 0.1 and 0.2 mm thick. The possible construction volume which we can produce in this way is 330 x 240 x 300 mm. The print layer calibrates itself automatically before each print. This ensures that the first layer adheres well to the print bed. The printing plane consists of a glass plate on which direct printing takes place. The glass is heated to approx. 60 degrees for this purpose. The plastic that is extruded from the nozzle has approx. 210 degrees.
The plastic used (PLA) is relatively robust and also suitable for mechanical applications. However, it is very sensitive to temperature. In warm environments, the plastic becomes soft and thus deforms easily. Without this temperature-related deformability, however, printing would not be so easy. Depending on the planned component, a water-soluble supporting material is also printed. This supports the construction during the printing process. Finally, the component is only held under water and the supporting material dissolves.
The prices for the plastic used already start at 20€/Kg and are thus comparatively cheap. This and the many "open source" components that can be downloaded from the internet make 3D printing easy and comparatively inexpensive.
This makes printing relatively inexpensive and is particularly suitable for the production of prototypes. However, printing takes a long time and depends on a number of variables such as layer thickness, which in turn affects accuracy and optics. Other parameters influence the robustness of the components.
The components produced in the DRZ are used when they neither require particularly strong robustness nor are used in particularly warm environments, e.g. as a holder for sensors. Each of our robots has more or less 3D-printed components somewhere.
At the moment, a dosimeter (for radioactivity) is being procured, so as soon as this arrives and we know the exact dimensions, we will use our 3D printer to design and print a precisely fitting holder, for example. This will be used on the D2.
For custom manufacturing, the model must first be created in a CAD programme (e.g. Solidworks or Solid Edge). The finished, digital model is then saved and sent through the 3D printer's software. In this software, the printing parameters (speed, layer thickness, degree of filling of the component, thickness of the outer walls ) are set. Only then do the print nozzles start moving and create the component. A long process for a small plastic component.
Our motion capture system consists of 40 individual special cameras and a powerful computer. The cameras are all networked with each other and deliver their information to this computer. The system is used to track robots (UAVs and UGVs) and determine their exact position in the hall. The users can then receive this information directly from the software. Alternatively, or in addition, there will be interfaces to transmit the determined positions in real time to the robot so that it can orientate itself in space. In this role, the system will represent a kind of virtual GPS system, which is needed, for example, when stable GPS reception is not possible indoors. In addition, tests (e.g. speed measurements) can be carried out precisely.
This works approximately like this: The robot has three "markers" attached to it: Three "markers" (balls of different sizes) are attached to the robot, which must be seen by at least two cameras. The more cameras have a clear view of the markers, the more accurate the tracking. Accuracies of up to approx. 0.03 mm can be measured in space. Not only the position but also the orientation (e.g. inclination of a robot during certain actions) can be determined. 40 cameras may sound a lot at first, when two are actually sufficient. However, since obstacles are often to be expected in the set-ups, only a few cameras will be able to see the three markers at any one time. And: The more cameras are used, the larger the area that can be tracked - and the accuracy increases.