It was a victorious moment last week when the children succeeded their first mission, but now we had to extend to other missions. With the next mission it is required to retrieve a “broken chair” and bring it to base. To do this in the most efficient way, the robot needs a grabbing device, powered by the third servo. (the first two servos are used for moving around). In practice, this means that the teams has to make a modification to the robot, a design change.
Because children of 9 years old design primarily with their hands we supplied them with a second robot set. The first, working version of the robot that is built for the first mission is kept (checked in) and with the second set a design variation is built. Besides adding a mechanism, the next version is also optimized for agility and control characteristics.
Another area where the team members have to pay attention to changes is in the robot programs. The NXT programming software is file based, so all dangers we know about file management apply. This was also experienced by the programmers of the team: with the blink of an eye a working program is overwritten by an experiment for something completely different. Fortunately the input for the the program were written down and it could be rebuilt very quickly, but it was a good learning moment to speak about version control.
Again this has a lot of parallels with the world of design for grown-ups. If we design in CAD and make modifications, the changes not always improve the models. Then it is of high importance that we can revert back to the previous situation and take another approach.
PDM is a great tool to facilitate this, instead of building up a sequence by hand in file names (device.SLDPRT, device1.SLDPRT, device2.SLDPRT, device_final.SLDPRT, device_change.SLDPRT… Can you put them in an unambiguous order???) PDM will save working versions for us in a secure vault. The design does not have to be renamed at all (no referencing issues) and it requires less effort (just apply the check-in function)
PDM would also help the FLL team in keeping their documents organized. To work out plans, they write mission plans and keep notes of measurements they do during tests. These measurements are related to a specific program and model in a specific version. In PDM we can have the means to save these documents and relate them to the relevant model data…