WildStang has continued with our beta testing activities, this week setting up a benchtop testing board and making some slightly more detailed observations about some of the control system components.
PDP
Noticing how tight of a fit our battery terminals are, we tried connecting the large copper screw terminals provided in the Kit of Parts, and discovered that they are too wide and do not fit under the plastic cover. This issue has been reported to FIRST and is already a topic of discussion. The other Burndy (silver) compression terminals provided in the Kit of Parts were a better fit, though still tight.
Also worth noting: The small screws on the terminal cover are Imperial (6-32, requiring a 5/64 key), while the larger ones are metric (M6). We’re mentioning this, as the sizes are printed under the cover. We figure this will be documented, or most teams will just try something until they find what fits, but those are the sizes.
VRM
Currently, the terminals on the VRM are 3.5mm pitch, so they’re pretty close together. Making sure wiring is neat, tight, and devoid of frayed ends is imperative to prevent unwanted shorts. It’s important to strip your wires to the appropriate length to fit into the terminals so that they grab and don’t pull out. It is documented as 5/16 inch, and we found it to be about 1/4 inch. A good way to get the correct length would be to put a mark on your work bench as a reference.
It also tends to emit a high pitched whine when not enabled (not unlike the sound of electrical students who have no room in the robot to wire), although this may be unique to our module.
Software
We are using Java, and so have some work to do to port our existing code to the new JVM platform. This is mostly due to us writing our own container classes (Lists, etc.) which can now use standard Java classes. Meanwhile, for the benchtop system, we have used some basic code that we haven’t had any issues with yet.
There are some changes to how the system is configured, such as dynamic IP address for the devices, but the current documentation was very helpful for walking us through using it all.
General Thoughts
Overall, we felt the system was easier and more efficient to assemble, mostly because the connections do not need crimping or soldering. As we mentioned previously, we find the Weidmuller connectors to be faster and easier to use, but they can be depressed fairly easily, which could be a risk for wires popping out. The whole setup occupies less surface area, making it easier to fit into robots that your mechanical team has seemingly designed specifically to hinder timely wiring.
Next meeting will be dedicated to troubleshooting and setting up/reading from the CAN bus that the new system heavily relies on.
More testing will occur in the next few weeks. Watch our calendar for upcoming events, and email us at betatest2015 (at) wildstang.org with any questions.
-WildStang Beta Test Team