Today it’s another Technology Tuesday of team frame! They also made a lot of progress and the complete frame is being produced as we speak. We expect to receive all milled parts, such as the hip structure and the bones, very soon. After this, the real work can finally start: the assembly of the whole exoskeleton!
During the assembly of the frame it is of course very important that all separate parts are connected to each other in a good way, so that the optimal stiffness and with that the safety of the exoskeleton is being guaranteed. Therefore, we make use of special connectors that fit each other perfectly and that are being connected by means of screws. In the first image one connector of the hip structure is shown, which will form the connection with the upper leg. The whole hip structure is shown in the second image. In order to connect these parts, the screw thread will go through the holes that are visible in the image, which will fit the holes of the connector of the upper leg perfectly. For these holes, we make use of inserts (helicoils). These are the small round components of the third image, on which also a part of a connector can be seen. The reason we do this is to make sure the screw thread of the screws we use to connect the connecting pieces will not break down in the aluminium, which is used for the frame. Screws of steal are namely harder and stiffer than the aluminium hole into which the screw goes. If you will put a lot of force to this bolt (this happens when Ruben is walking in the exoskeleton for example), the screw thread will slowly become defective. These helicoils make sure the steal of the bolt will pull on the steal of the helicoil instead of the aluminium. In this way, the screw thread will be loaded less and it is able to divide the forces better.
Besides, we make use of Nordlock locking rings for all connections. These makes sure the bolts cannot get loose by relaxation of the material or by just some vibration. These rings are designed in such a way that there is more force needed to unscrew them than when you screw them on.
In this way, we are able to produce a very strong and stiff frame, which is of course very important to let Ruben walk safely in the exoskeleton once it is finished!