Sawppy the Rover

When I work on Sawppy, I test and run indoors. At DTLA Maker Faire Sawppy ran all over, both indoors and out. Most of the time people were playing with Sawppy on a piece of artificial turf at Maguire Gardens. This is an outdoor space where people would walk their dogs, raising obvious sanitation concerns running Sawppy on my home carpet after the event.

Well, after a long day of work, who doesn’t enjoy kicking off their shoes and soaking their feet? I could give Sawppy the same royal treatment. All six wheels were removed and soaked in a tub filled with a mixture of water and household bleach. A retired toothbrush was used to scrub off dirt particles clinging to the wheel. Hopefully this removed most of the contaminants Sawppy might have picked up during the event.

It was also a good time to perform an inspection to see how Sawppy held up mechanically. In addition to the set screw mentioned yesterday, a few chassis mounting screws have fallen out and need to be replaced. I designed plenty of redundancy in these mounts so there was little risk of Sawppy falling apart.

After a few hours of soaking, the wheels were hung up to dry like old socks. What has six rover wheels but is not a rover? This laundry rack.

(Cross-posted to NewScrewdriver.com)

Yesterday Sawppy went on an adventure to the downtown Los Angeles Mini Maker Faire. There Sawppy found a receptive and appreciative audience. There were a lot of enchanted kids, interested parents, and other makers who might be building their own Sawppy rovers.

The morning started out with Sawppy sitting on a table alongside a few different builds of JPL open source rover. Eric’s build is on the left in black and white, Santa Susana High School build is on the right with purple printed parts.

Taking Sawppy around and talking to individuals about Sawppy was a lot of fun and something I’ve done in other contexts before. I have hopes for a few of the contacts to develop into something cool for Sawppy’s future. What’s new this time was that I also signed up to give a short 15-minute presentation about Sawppy and that took more work and preparation. Thanks to the 2-minute “lightning talk” opportunities at Hackaday LA the past few months I’m less nervous about public speaking than I used to be, but I still got pretty stressed about it. I’m sure it’s a matter of practice and the more I can take advantage of such opportunities the better I’ll get.

Outside of the presentation, Sawppy and I spent most of our time on the astroturf across the walkway from the officially assigned display area. It was a hilly part of the park which meant there were no tables or booths set up there, and it was a good place to demonstrate rover suspension in action. I had a spare phone set up to be Sawppy control and handed the control to anyone who wanted to pilot Sawppy for a bit.

Most were content to run around the turf. Some of the little ones tried to run Sawppy into their siblings. A few ran into the bushes beyond the turf for a more rugged demonstration of Sawppy chassis. A perpetual favorite is to have Sawppy climb over shoes.

Thanks to refinements to improve robustness over the past few months, Sawppy came out of the experience with only a slightly wobbly left rear wheel that was easily repaired by tightening the set screw on the left rear steering servo coupler. A great improvement over earlier outings!

(Cross-posted to NewScrewdriver.com)

The Downtown Los Angeles (DTLA) Mini Maker Faire, hosted at the Los Angeles Public Library central location, is coming up this weekend and my rover Sawppy will be among the many maker projects at the event.

Sawppy will be one of several rovers present. JPL’s Open Source Rover team should be there with their original build, SGVHAK will be there with the beta build rover I contributed to, which inspired my Sawppy and they’ll all be hanging out together.

The JPL team will also be giving a brief presentation in the KLOS Children’s Theater upstairs about their rover project, followed by an even briefer presentation by me on building Sawppy. Both of these talks are listed on the workshop schedule though (as far as I know) there is no hands-on workshop activity planned. Sawppy will be present and running for people to see up close, but no assembly (and certainly no disassembly!) is planned. I may bring an extra corner steering unit for people to play with, and they’ll be welcome to take that apart and put it back together, but not much beyond that.

(Cross-posted to NewScrewdriver.com)

A few days ago I noticed a sudden spike in internet traffic to Sawppy – page views on my personal blog, Sawppy’s Hackaday.io project page, the Github repo, and YouTube video all rose dramatically. It took a little digging around various statistics reporting pages to figure out where the interest was coming from. Answer: someone had submitted Sawppy to Hacker News giving Sawppy a brief taste of internet fame.

Given the general attention span of the internet at large, the traffic disappeared just as quickly as it came. But in that brief moment in time, a few thousand people spared a few seconds (or more) of their lives to look over Sawppy and that’s more than what I had before.

And this bit of exposure might lead to other interesting projects down the line. It seems to have caught the eye of someone with interest in the Pi Wars robot competition. Sawppy’s current configuration is indeed controlled by a Raspberry Pi, but according to contest rules Sawppy is too big to fit as-is. I’m not sure a six-wheeled rocker-bogie suspension would be useful for any contest objectives (challenges) in Pi Wars. But it would absolutely make my day if I see one of the competitors downscale Sawppy to fit in the size envelope, thereby creating a “Sawppy Jr.”

https://twitter.com/pinski1_/status/1061997311843287041

(Cross-posted to NewScrewdriver.com)

I saw that RaspberryPi.org had an article on JPL Open Source Rover. In the comments section, there was a comment by Daniel Perron (who had also commented on this project page) mentioning Sawppy. I think Daniel should have a project page for his own Sawppy but I haven't seen one under his Hackaday.io account. 

Which is a shame, because his rover is making good progress and his work totally deserves attention. So I'm going to draw attention to his build on my Sawppy page here.

Here's a scaled-down copy of the image he linked from his RaspberryPi.org comment. From this picture I can see a few changes from my design. The biggest change is in the structural beams. Daniel is using something other than the Misumi 3-series 15mm extrusion that I used. I'm curious to see how well these beams work. Their uninterrupted square profile should make Daniel's Sawppy more rigid than mine, and more rigidity is always good.

And here's his YouTube clip showing his travel motor turning a wheel under control of his own servo control code.

I'm super excited to see another Sawppy taking form. Your rover looks great, Daniel! Great job and I look forward to seeing your future progress.

The behind-the-scenes path of Sawppy's design and fabrication was told one small (~300 words) story at a time on the build blog, and the storytelling has finally caught up to Sawppy's current version 1.0 status. Now that Sawppy is running around, I'm going to put a pause on hardware iteration for a while and focus on software.

To celebrate this milestone, here's a group picture of Sawppy, plus all earlier iterations of 3D-printed components, with empty spools representing filament consumed.

As part of researching into how I can build Sawppy, I evaluated several serial bus servos. This information is useful for all kinds of projects, not just motorized Mars rover models, so an overview has been shared to the entire Hackaday.com community.

The mechanical assembly instructions have been posted!

For visual reference, the guide has all the pictures I took while I reassembled my rover with parts printed in PETG.

While continuing to add to Sawppy build instructions, I seemed to have run into some kind of limit on the Hackaday.io infrastructure. As I continued to add pictures to later assembly steps, the pictures from earlier steps started disappearing!

I can recover them, I'll just have to retrieve the originals from my camera's memory card and redo all the photo cropping and resizing. But with this loss of data I'm moving Sawppy build instructions elsewhere. I like the format of iFixit.com but their platform spinoff Dozuki.com starts at $20/mo and that's more than I can justify for this hobby project. I'll keep looking for other alternatives.

In the short term, I'll put instructions on Github.com. It's a bit of a square peg in a round hole but I have more confidence pictures won't surprisingly disappear from my Github repository.

Now that I'm satisfied with the rough draft printed in PLA plastic, I'm printing a final draft in more durable PETG plastic. And also printing slower for better accuracy and detail. As these PETG parts come off the printer, I'll take pictures to illustrate assembly instructions. 

Keep an eye on the "Instructions" section of this project page, it will grow over the next few days/weeks.