Real paper documentation!

Discuss using and implementing the NearZero motor controller and the RoboWheel hubmotor.
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slomobile
Posts: 8
Joined: Tue Aug 25, 2020 4:21 pm

Real paper documentation!

Post by slomobile »

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This is great, keep the questions/comments coming.
~Justine
Robot Mobility Kit just arrived and it looks amazing. 2 black and white printed manuals (RoboWheel and NearZero) were included, but I still had to refer to the .pdf color version on the website because the wire color order for the encoder IDC connector was not called out in text.

When holding the connector and wires as shown in RoboWheel manual page 2 step 3, tab up, from left to right colors are
Pos 6 Empty, Pos 5 Empty, Pos 4 Grey Encoder B, Pos 3 White Encoder A, Pos 2 Red 5V Out, Pos 1 Black GND
If using Hall Sensors instead, colors are
Pos 6 Empty, Pos 5 Yellow Hall C, Pos 4 Blue Hall B, Pos 3 Green Hall A, Pos 2 Red 5V Out, Pos 1 Black GND
The hall wires are the same color as the U,V,W Phase wires, but smaller.

If extending encoder wires with grey ribbon cable, convention dictates the single wire with red tracer connects to position 1. In this case, position 1 mates with the black GND wire from RoboWheel. This and the back and forth numbering pattern catch a lot of newbies. They incorrectly assume IDC numbering is like DIP numbering.

If you were to edit the RoboWheel Manual, a useful feature would be if the bolt pattern Figure 6 on Page 5 were rendered actual size in the printed manual and had crosshairs at the boltholes so that it may be cutout and used as a drill template. NearZero manual page 9 could use the same treatment on the top view image.

RoboWheel radial and axial load ratings would be a handy spec to have noted. You know someone will make a hoverboard, they should know if it will hold them.

Despite these minor omissions, you've made useful clear complete documentation. The FIRST Robotics Competition high school teams I mentor would have no trouble making use of this. I would too if only I could remember where I left my wire strippers.

Looking forward to hearing about the parallel elastic arm and PF-1. Consider this an inquiry.

Edit: The cable covering from the center of one RoboWheel had worked itself out of its hole during shipping. It goes back with a bit of massage. Looks like the deep cut foam packing is just a bit too deep in the center. Equal number of packing foam layers top and bottom might resolve that.

justine
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Joined: Sun Feb 23, 2020 2:34 am

Re: Real paper documentation!

Post by justine »

Yes I'm thinking it might be time for a color duplex printer, but nonetheless I think it's important to include an actual manual with things like this.

Thanks for the comments. I've been learning a lot lately about how people interpret information and seeing how to make things even clearer in the future. I have a list going for the next version of the NearZero (though I won't get to working on it until next year, after the 4G phone is released).

>RoboWheel radial and axial load ratings would be a handy spec to have noted. You know someone will make a hoverboard, they should know if it will hold them.

I've been worried about that, so I think I wrote somewhere that it's for robotics mobility and not carrying people, though this is mostly because the NearZero doesn't have enough oomph for an application like that. I need to do more testing on the Wheel to what its limitations really are.

>Despite these minor omissions, you've made useful clear complete documentation. The FIRST Robotics Competition high school teams I mentor would have no trouble making use of this. I would too if only I could remember where I left my wire strippers.

That is REALLY good to see, thank you. Poor documentation drives me absolutely crazy. Mostly its a problem in the open source hardware community, but even big companies occasionally falter (looking at your SMT multi-band 4G antennas, Molex!).

>Looking forward to hearing about the parallel elastic arm and PF-1.

Eh, basically I put the PF-1 on there if anyone wants a one-off build to experiment with, but it's mostly a stepping stone to a more consumer-ready model. I can't wait to have the time to work on that and the elastic arm. Too many balls in the air, ugh.

>Edit: The cable covering from the center of one RoboWheel had worked itself out of its hole during shipping. It goes back with a bit of massage. Looks like the deep cut foam packing is just a bit too deep in the center. Equal number of packing foam layers top and bottom might resolve that.

I don't like that covering. I was tempted to remove it, and indeed did for some of the ones I sent out. Not sure it's useful.

SteveC
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Joined: Sat Mar 21, 2020 1:26 pm
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Re: Real paper documentation!

Post by SteveC »

(looking at your SMT multi-band 4G antennas, Molex!)
Sorry I should have chipped in earlier but I don't normally venture this side of the forum.

Molex: they make some amazing chip antennas but all chip antenna manufacturers are coy with data because the Mobile Equipment (phone) body is an equally important part of the antenna. This makes the antenna characteristics board dependant and the reason reference test boards are approx chocolate bar (phone) shaped. It's also the reason RF engineers command such good money (except in academia) and why RF is sometimes referred to as the 'black art' of electronics!

In general the approach would be to try to follow manufacturer application guidelines as closely as possible, then measure impedance against frequency with a vector network analyser (VNA), it needn't be an expensive VNA. High accuracy isn't necessary, good low cost hobby VNAs are available (NanoVNA) but finding one to cover up to 2.7GHz might be a problem. Oh and only run the test in an RF anechoic chamber or a screened box lined with EM absorbing material otherwise you will be transmitting broadband interference! Also the test connection can be tricky, I suggest a short length of micro coax with ferrite beads as a poor person's balun (the VNA connection end of the test board is where you might reasonably hold the phone, so a perfect balun isn't necessary).

When you have the combined phone and chip antenna impedance, then you can select the matching components.

I hope that explains the mystery (with chip antennas at least).

This is in the wrong thread isn't?!

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